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Class 9 Science Case Study Questions Chapter 3 Atoms and Molecules

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Case study Questions in Class 9 Science Chapter 3 are very important to solve for your exam. Class 9 Science Chapter 3 Class 9 Science Case Study Questions have been prepared for the latest exam pattern. You can check your knowledge by solving case study-based questions for Class 9 Science Chapter 3 Atoms and Molecules

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In CBSE Class 9 Science Paper, Students will have to answer some questions based on Assertion and Reason. There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.

Atoms and Molecules Case Study Questions With Answers

Here, we have provided case-based/passage-based questions for Class 9 Science Chapter 3 Atoms and Molecules

Case Study/Passage-Based Questions

Case Study 1: The knowledge of the valencies of various radicals helps us to write the formulae of chemical compounds. The total positive charge on positive ions (cations) is equal to the total negative charge on negative ions (anions) in a molecule. Therefore, in writing the formula of a compound, the positive and negative ions are adjusted in such a way that the total number of positive charges of positive ions (cations) becomes equal to the total number of negative charges of negative ions (anions). There is another simple method for writing the formulae of ionic compounds. In this method, the valencies (or positive or negative charges) of the ions can be ‘crossed over’ to give subscripts. The purpose of crossing over of charges is to find the number of ions required to equalise the number of positive and negative charges.

Element X has two valencies 5 and 3 and Y has valency 2. The elements X and Y are most likely to be respectively (a) copper and sulphur (b) sulphur and iron (c) phosphorus and fluorine (d) nitrogen and iron.

Answer: (d) nitrogen and iron.

The formula of the sulphate of an element X is X 2 (SO 4 ) 3 . The formula of nitride of element X will be (a) X 2 N (b) XN 2 (c) XN (d) X 2 N 3

Answer: (c) XN

The formula of a compound is X 3 Y. The valencies of elements X and Y will be respectively (a) 1 and 3 (b) 3 and 1 (c) 2 and 3 (d) 3 and 2

Answer: (a) 1 and 3

Case Study/Passage Based Questions

Case Study 2: A mole of an atom is a collection of atoms whose total mass is the number of grams equal to the atomic mass. Since an equal number of moles of different elements contain an equal number of atoms it becomes convenient to express the amounts of the elements in terms of moles. A mole represents a definite number of particles viz, atoms, molecules, ions or electrons. This definite number is called the Avogadro number or Avogadro constant which is equal to 6.022 × 1023. Hence a mole represents 6.022 × 1023 particles of the substance. One mole of a substance represents one gram-formula of the substance. One mole of a gas at standard temperature and pressure occupies 22.4 litres.

How many grams of sodium must be taken to get 1 mole of the element? (a) 23 g (b) 35.5 g (c) 63.5 g (d) 46 g

Answer: (a) 23 g

What is the mass in grams of a single atom of chlorine? (Atomic mass of chlorine = 35.5) (a) 6.54 × 10 23 g (b) 5.9 × 10 –23 g (c) 0.0025 g (d) 35.5 g

Answer: (b) 5.9 × 10–23 g

How many number of moles are there in 5.75 g of sodium ? (Atomic mass of sodium = 23) (a) 0.25 (b) 0.5 (c) 1 (d) 2.5

Answer: (a) 0.25

What is the mass in grams of 2.42 mol of zinc? (Atomic mass of Zn = 65.41) (a) 200 g (b) 25 g (c) 85 g (d) 158 g

Answer: (d) 158 g

Case Study 3: According to Dalton’s atomic theory, all matter whether an element, a compound, or a mixture is composed of small particles called atoms which can neither be created nor destroyed during a chemical reaction. Dalton’s theory provides a simple explanation for the laws of chemical combination. He used his theory to explain the law of conservation of masses, the law of constant proportions, and the law of multiple proportions, based on various postulates of the theory. Dalton was the first scientist to use the symbols for the elements in a very specific sense. When he used a symbol for an element he also meant a definite quantity of that element, that is one atom of that element.

Which postulate of Dalton’s atomic theory is the result of the law of conservation of mass? (a) Atoms can neither be created nor destroyed. (b) Each element is composed of extremely small particles called atoms. (c) All the atoms of a given element are identical. (d) During chemical combination, atoms of different elements combine in simple ratios.

Answer: (a) Atoms can neither be created nor destroyed.

Which postulate of Dalton’s atomic theory explains law of definite proportions? (a) Atoms of an element do not change during a chemical reaction. (b) An element consists of atoms having fixed mass and the number and kind of atoms in a given compound is fixed. (c) Different elements have different kind of atoms. (d) Atoms are of various kinds

Answer: (b) An element consists of atoms having fixed mass and the number and kind of atoms in a given compound is fixed.

“If 100 g of calcium carbonate (whether in the form of marble or chalk) is decomposed, 56 g of calcium oxide and 44 g of carbon dioxide are formed.” Which law of chemical combination is illustrated by this statement? (a) Law of constant proportions (b) Law of conservation of mass (c) Law of multiple proportions (d) Law of conservation of energy

Answer: (b) Law of conservation of mass

When 5 g calcium is burnt in 2 g oxygen, 7 g of calcium oxide is produced. When 5 g of calcium is burnt in 20 g of oxygen, then also 7 g of calcium oxide is produced. Which law of chemical combination is being followed? (a) Law of conservation of mass (b) Law of multiple proportions (c) Law of constant proportions (d) No law is being followed.

Answer: (c) Law of constant proportions

Case Study 4: Atoms and molecules are the building blocks of matter. An atom is the smallest unit of an element that retains its chemical properties, while a molecule is a group of two or more atoms held together by chemical bonds. Atoms consist of a positively charged nucleus, which contains protons and neutrons, surrounded by negatively charged electrons in energy levels or shells. The number of protons in an atom determines its atomic number and defines its unique identity as an element. The electrons in an atom occupy specific energy levels, and the outermost shell is known as the valence shell. Atoms gain, lose, or share electrons to achieve a stable electron configuration, forming chemical bonds and giving rise to molecules. Understanding the concept of atoms and molecules is crucial for comprehending various chemical reactions and the composition of substances.

What is the smallest unit of an element that retains its chemical properties? a) Proton b) Electron c) Nucleus d) Atom Answer: d) Atom

What is a group of two or more atoms held together by chemical bonds called? a) Element b) Compound c) Molecule d) Nucleus Answer: c) Molecule

What are the positively charged particles present in the nucleus of an atom called? a) Electrons b) Protons c) Neutrons d) Valence electrons Answer: b) Protons

Which part of an atom contains electrons in energy levels or shells? a) Protons b) Neutrons c) Nucleus d) Valence shell Answer: d) Valence shell

What do atoms do to achieve a stable electron configuration? a) Gain, lose, or share electrons b) Absorb protons c) Increase their atomic number d) Create chemical bonds Answer: a) Gain, lose, or share electrons

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Case Studies in Science Education

A video library for k-8 science teachers: 25 half-hour video programs and guides.

These video case studies take science education reform to a personal level, where individual teachers struggle to make changes that matter. Follow Donna, Mike, Audrey, and other science teachers as they work to adopt one or more research-based interventions to improve science teaching and learning. Each case follows a single teacher over the course of a year and is divided into three modules: the teacher's background and the problem he or she chooses to address, the chosen approach and implementation, and the outcome with assessment by the teacher and his or her advisor. Average running time: 1/2 hour. Program guides and supporting materials (PDF) Program guides and supporting materials (Link)

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Class 3 Science MCQ Test (Online Available)

Free mcq test, table of content.

3. Social Science

States of matter Test 2

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The Class 3 Science MCQ is a form of objective questions in which the test takers need to select any one of the options. Students can select the accurate option by completing all chapters included in Class 3 Science syllabus. After attempting the objective questions, students can analyse the given answers of Class 3 Science as the question analysis is given on the website.

The Class 3 Science MCQ are considered to be standardised tests which can be useful for both teachers and students. Teachers can use the study resource so that they can provide the ready made questions of Class 3 Science to students for practising. Students can also use the study resource of objective questions to practise and to understand the concepts in a better way.

Science MCQ Class 3 Online Test

Students can attempt the Science MCQ Class 3 in an online mode so that they don’t face any difficulty in attempting questions. Regular solving questions from the Class 3 Science, can help students to be more confident while attempting objective questions. It can also help students to score well in the Class 3 Science final, accordingly they can be promoted to the next grade.

Where Can Students Find Class 3 Science MCQ?

Students can find the Class 3 Science MCQ from the Selfstudys website, steps to attempt the MCQ are clearly explained below:

Open the Selfstudys website.
Bring the arrow towards the CBSE which can be seen in the navigation bar.
A drop down menu will appear, select MCQ Test from the given list.

Class 3 Science MCQ, Class 3 Science MCQ Test, Class 3 Science Online MCQ, MCQ Test for Class 3 Science, Science MCQ Test for Class 3, Science MCQ Class 3 Online Test

A new page will appear, select Class 3th from the list of classes.
Click Science from the list of subjects.
A drop down menu will appear, select Latest Test from the list.

Again a new page will appear, select any of the chapters to Start Test to practise.

Features of Class 3 Science MCQ

The Class 3 Science MCQ are those questions which are provided with 4 options, this is one of the important feature of the MCQ, other features are:

Question Analysis is Given: In the analysis, knowledge about the correct ; wrong and skipped questions are given so that students can improve accordingly.
Rank is Given: Rank refers to the position or order in reference to the performance; students can look through the rank after attempting Science Class 3 MCQ.
Solutions are Given: It is very important for students to solve their doubts after attempting Science Class 3 MCQ as it is provided in the website.
Redo Option is Given: Students are provided with the option of redo, so that they can attempt the Science MCQ Class 3 once again without getting stuck.

All Chapters are Covered: In the latest MCQ of Class 3 Science MCQ, students are provided with questions related to all the chapters.
For CBSE Board: The Science MCQ Class 3 are basically for students following the CBSE syllabus as all the chapters are arranged and organised according to it.

Top 6 Benefits of Class 3 Science MCQ

The Class 3 Science MCQ offers ample of benefits, some of the benefits are discussed below:

Scoring: The Science MCQ Class 3 is considered to be easy scoring as students just need to select the accurate option to score 1 mark and they don’t need to write a subjective answer.
Provides Quick Feedback: The Science Class 3 MCQ provides quick feedback to the test takers so they can try to improve then and there.
Saves Time: The Science MCQ of Class 3 can be analysed and completed quickly without wasting much time in looking for answers.
Highly Reliable: The content inside the Science MCQ Class 3 is highly reliable as it is created with good research so that students can attempt all questions without confusions.
Mobile Friendly: Students can attempt the Science Class 3 MCQ from their smartphones as it can be attempted from anywhere and wherever possible.
Helpful in Self Evaluation: The multiple choice questions of Class 3 Science can be helpful while self evaluation: ability to examine, accordingly students can improvise.

How to Mark the Right Answer While Attempting Class 3 Science MCQ?

It is must for students to mark the right answer while attempting Class 3 Science MCQ, then only they can improvise their score, tips to mark the right answer are:

Read the Question Carefully: Students need to read the multiple choice questions of Class 3 Science, then only they can get an idea about what is asked accordingly they can answer it.
Read the Options: Students are advised to read all the 4 options while attempting Class 3 Science MCQ so that they can guess the accurate option.
Try to Eliminate Incorrect Options: Students are advised to eliminate obvious incorrect options from the Science Class 3 MCQ, this can increase the chances of selecting the right option.
Look for Clues: Students are advised to look for clues which can be visible in the questions of Class 3 Science, this can ease the process of selecting the right option.
Double Check the Answers: Students need to double check the answer given while attempting the Class 3 Science MCQ so as to decrease the amount of silly mistakes.

How To Analyse the Answers After Solving Class 3 Science MCQ?

After solving Class 3 Science MCQ, it is very important for students to analyse, accordingly they will be able to know their strengths and weaknesses as well as gaps in the understanding of the chapter, tips to analyse the answers are discussed below:

Review Answers: Students need to analyse the answers of Science MCQ Class 3 so that they can get an idea about wrong as well as right answers.
Review the Correct Answers: Students need to revise the correct answers of Science MCQ so that they can get an idea about why the answers are right as well as strong topics.
Review the Incorrect Answers: Students are advised to review the incorrect answers of Science MCQ so that they can identify misconception and errors in their thinking.
Identify the Pattern: Students are advised to identify patterns or concepts in those incorrect questions of Class 3 Science MCQ so that they can study accordingly.
Note Down the Mistakes: Students need to note down the mistakes in a scrap paper or in a separate book, this can help them to rectify quickly.

When is the Right Time to Solve the Class 3 Science MCQ?

The best time to solve the Class 3 Science MCQ depends upon the student’s learning style and their preferences, right time to solve the questions are discussed below:

After Completing a Topic: The Science MCQ Class 3 can be very useful after completing a particular topic as it helps to revise or review the topic.
As Part of the Study Schedule: Students can incorporate the Science Class 3 MCQ into their study schedule, accordingly they can track their performance on a daily basis and improve their understanding of the subject.
Before an Exam or Assessment: The Class 3 Science MCQ can be helpful during an exam or assessment as it helps students to test their knowledge and can identify the gaps.
During Revision: The Science Class 3 MCQ can be a useful tool as it helps students to know the key concepts and can increase the level of understanding.
To Improve the Test Taking Skills: When students need to improve their test taking skills, they can take the help of Class 3 Science MCQ as it helps to improve the time management skills as well as critical thinking.

How to Prepare Well for Class 3 Science MCQ?

Preparing for the Class 3 Science MCQ requires a combination of understanding the concepts and practising the objective questions, here are some tips to be followed so that students can prepare well and score good marks:

Study the Concepts: The first step in preparing the Science MCQ Class 3 is to study the concepts thoroughly so that students can have a better understanding.
Focus on Important Topics: Identify those topics and concepts which are likely to be covered in the Science Class 3 MCQ, this can help students to score better.
Practise Regularly: It is important for students to practise Science Class 3 MCQ regularly so that they can get an idea about the test format and can easily improve their test taking skills.
Analyse the Mistakes: Students need to analyse the mistakes done while attempting Class 3 Science MCQ so that they can know their weaknesses and study accordingly.
Form a Study Schedule: Students need to allocate a specific time to cover the concepts and to practise Class 3 MCQ of Science so that they can analyse their progress.
Use Reference Books: Students can utilise the reference books so that they can practise vast amounts of Class 3 multiple choice questions.
Revise Regularly: Students are advised to revise all concepts on a regular basis then only they can be prepared well for Class 3 MCQ Science.
Seek Help: If in case students are struggling with any of the topics or concepts, they can seek help from the teachers so that they can be well prepared for Class 3 Science MCQ.

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Science is an intriguing subject and it is important to learn thoroughly to know the real facts behind many occurrences such as, why is the sky blue?, Why are there 7 colours in the rainbow? Hence, it is essential for the students to know the importance of science in order to excel in this subject. In CBSE class 3 science, students explore concepts such as water, food that we eat, rain and many more.

We at Byju’s provide all the notes, sample papers, mock tests and previous year question papers to help students score well in their main exam. You can also get the complete CBSE class 3 science syllabus and all the important study materials of class 3 science to get an idea about the subject from an early age.

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CBSE Worksheets for Class 3 Science

CBSE Worksheets for Class 3 Science: One of the best teaching strategies employed in most classrooms today is Worksheets. CBSE Class 3 Science Worksheet for students has been used by teachers & students to develop logical, lingual, analytical, and problem-solving capabilities. So in order to help you with that, we at WorksheetsBuddy have come up with Kendriya Vidyalaya Class 3 Science Worksheets for the students of Class 3. All our CBSE NCERT Class 3 Science practice worksheets are designed for helping students to understand various topics, practice skills and improve their subject knowledge which in turn helps students to improve their academic performance. These chapter wise test papers for Class 3 Science will be useful to test your conceptual understanding.

CBSE Class 3 Science Worksheets PDF

All the CBSE Worksheets for Class 3 Science provided in this page are provided for free which can be downloaded by students, teachers as well as by parents. We have covered all the Class 3 Science important questions and answers in the worksheets which are included in CBSE NCERT Syllabus. Just click on the following link and download the CBSE Class 3 Science Worksheet. CBSE Worksheets for Class 3 General Science can also use like assignments for Class 3 Science students.

Worksheet for Class 3 Science Assignment 1
Worksheet for Class 3 Science Assignment 2 Safety and First Aid
Worksheet for Class 3 Science Assignment 3 Our Body
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Worksheet for Class 3 Moral Science

Worksheet for Class 3 Moral Science Assignment

Advantages of CBSE Class 3 Science Worksheets

By practising NCERT CBSE Class 3 Science Worksheet , students can improve their problem solving skills.
Helps to develop the subject knowledge in a simple, fun and interactive way.
No need for tuition or attend extra classes if students practise on worksheets daily.
Working on CBSE worksheets are time-saving.
Helps students to promote hands-on learning.
One of the helpful resources used in classroom revision.
CBSE Class 3 Science Workbook Helps to improve subject-knowledge.
CBSE Class 3 General Science Worksheets encourages classroom activities.

Worksheets of CBSE Class 3 Science are devised by experts of WorksheetsBuddy experts who have great experience and expertise in teaching Maths. So practising these worksheets will promote students problem-solving skills and subject knowledge in an interactive method. Students can also download CBSE Class 3 Science Chapter wise question bank pdf and access it anytime, anywhere for free. Browse further to download free CBSE Class 3 Science Worksheets PDF .

Now that you are provided all the necessary information regarding CBSE Class 3 Science Worksheet and we hope this detailed article is helpful. So Students who are preparing for the exams must need to have great solving skills. And in order to have these skills, one must practice enough of Class 3 General Science revision worksheets . And more importantly, students should need to follow through the worksheets after completing their syllabus. Working on CBSE Class 3 Science Worksheets will be a great help to secure good marks in the examination. So start working on Class 3 General Science Worksheets to secure good score.

CBSE WorkSheets for Class 3

Modes and Means of Transport - Class 3 Notes & Olympiad Questions

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Modes and Means of Transport - Class 3 Sub Topics

Land transport, air transport, water transport, special vehicles.

Solved Questions on Modes and Means of Transport

Transportation is how we move things, including animals, people, and goods, from one place to another.

a) Means of transport refer to the different ways or methods people use to travel and carry goods from one place to another. For example, cars, bicycles, trains, aeroplanes and ships are different means of transport.

b) Modes of transport refer to the different categories or types of transportation. They can be divided into three different categories: land transport, water transport, and air transport.

Land transport is how we move things, like goods and people, from one place to another on land.

There are two main types of land transport: road transport and rail transport.

Road Transport

a) Roads are like paths that connect different places, like villages, towns, and cities. b) They allow us to travel easily from one place to another. c) We use vehicles like cars, trucks, scooters, bicycles, buses, and trains on roads to carry passengers and goods.

Rail Transport

a) Rail transport uses trains that run on special tracks. b) There are different kinds of trains, such as passenger trains for people, goods train for transporting things, and even metro or subway trains that go underground in big cities. c) Rail transport is useful when we need to travel really far or when we want to move a large number of people or goods. d) Nowadays, many trains run on electricity, which is better for the environment.

a) Air transport is a way of moving things like goods and people through the air to reach faraway places quickly.

b) Air transport is the fastest way to travel and deliver things, but it can also be more expensive compared to other means of transport like roads or trains.

c) We use special vehicles called helicopters and aeroplanes for this, and they are called means of air transport.

d) Another interesting thing about air transport is the hot air balloon. It's not used for regular transportation, but people can go on pleasure rides in hot air balloons.

a) Water transport is a way of moving things like goods and people on water from one place to another.

b) We use different types of water vehicles for this, such as boats, yachts, submarines, cargo ships, steamers, sailboats, and cruise ships. These are called means of water transport.

c) Boats are smaller water vehicles that sail along big rivers and lakes. They can be used for fishing and transportation in some areas.

d) Ships, on the other hand, are bigger and sail on seas and oceans. They carry lots of people and goods from one place to another, often for long distances.

e) Submarines are special water vehicles that can travel underwater.

f) Water transport is usually slower compared to road, rail, or air transport. However, it's still an important means of transportation, especially for carrying large quantities of goods or travelling across oceans.

g) Water transport allows us to explore and connect with different parts of the world through rivers, lakes, seas, and oceans.

a) Special vehicles are vehicles that have unique purposes and are used for specific tasks.

b) Some examples of special vehicles are bulldozers, tractors, cable cars, police vans, ambulances, hot air balloons, fire trucks, postal vans, etc.

Class 3-Different types of special vehicles

A list of means of transport

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The NCCSTS Case Collection, created and curated by the National Center for Case Study Teaching in Science, on behalf of the University at Buffalo, contains over a thousand peer-reviewed case studies on a variety of topics in all areas of science.

Cases (only) are freely accessible; subscription is required for access to teaching notes and answer keys.

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Development of the NCCSTS Case Collection was originally funded by major grants to the University at Buffalo from the National Science Foundation , The Pew Charitable Trusts , and the U.S. Department of Education .

Class 3 Science Chapter 16 Light, Sound, and Force

NCERT Solutions for Class 3 Science Chapter 16 Light, Sound, and Force with worksheets. All the chapters of Science in standard 3 are suitable for CBSE and State board students. It is given here in updated format for the 2024-25 curriculum. Students find it as the best study material for learning Science in standard 3. It is free to use and follows the educational guidelines.

Class 3 Science Chapter 16 Study Material
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Light is a form of energy. It removes darkness. It helps us to see. The sun is the main source of light on the earth. But it can give light only during the day. We use electric bulbs, candles, lamps, etc. during the night to get light.

Sound is also a form of energy. It can travel in all directions. It helps us to hear.

When we strike two objects, sound is produced.

We hear various types of sound. Some sounds are pleasant while some sounds are unpleasant. A sweet song is a pleasant sound. But the sound of horns is unpleasant. Unpleasant sound is irritating. Unpleasant sound is called noise. The sound of music is pleasant. But a loud music is unpleasant.

Force is referred to as push and pull. Force can move an object.

Push and pull is called force. When we push an object, we apply force. When we pull an object, we also apply force.

1. Light is a form of energy. It helps us to see. 2. Sound helps us to hear. 3. Force is referred to as push and pull. 4. Sun is the main source of light on the earth. 5. Some objects that give us light are called luminous objects. 6. The objects which do not give light are called non-luminous objects. 7. Light travels in a straight line. 8. Unpleasant sound is called noise.

Which of the following is a luminous object?

Candle is a luminous object.

View Answer

A shadow is ____________.

A shadow is Black.

Which of the following is a pleasant sound?

Sound of a flute is a pleasant sound.

What force can do?

Force can do: (a) Move an object (b) Change the direction of a moving object (c) Stop a moving object

Listening music at high volume can make us

Listening music at high volume can make us Deaf.

1. Light can remove darkness. 2. Sound travels in only one direction. 3. In solar eclipse the sun becomes invisible. 4. Pleasant sound is irritating. 5. Force can change the shape of an object.

Answers: 1. T 2. F 3. T 4. F 5. T

Light is a form of energy. It removes darkness. It helps us to see.

Force can move an object.

When the moon comes in between the sun and the earth, solar eclipse occurs.

Our Mission

Making Learning Relevant With Case Studies

The open-ended problems presented in case studies give students work that feels connected to their lives.

Students working on projects in a classroom

To prepare students for jobs that haven’t been created yet, we need to teach them how to be great problem solvers so that they’ll be ready for anything. One way to do this is by teaching content and skills using real-world case studies, a learning model that’s focused on reflection during the problem-solving process. It’s similar to project-based learning, but PBL is more focused on students creating a product.

Case studies have been used for years by businesses, law and medical schools, physicians on rounds, and artists critiquing work. Like other forms of problem-based learning, case studies can be accessible for every age group, both in one subject and in interdisciplinary work.

You can get started with case studies by tackling relatable questions like these with your students:

How can we limit food waste in the cafeteria?
How can we get our school to recycle and compost waste? (Or, if you want to be more complex, how can our school reduce its carbon footprint?)
How can we improve school attendance?
How can we reduce the number of people who get sick at school during cold and flu season?

Addressing questions like these leads students to identify topics they need to learn more about. In researching the first question, for example, students may see that they need to research food chains and nutrition. Students often ask, reasonably, why they need to learn something, or when they’ll use their knowledge in the future. Learning is most successful for students when the content and skills they’re studying are relevant, and case studies offer one way to create that sense of relevance.

Teaching With Case Studies

Ultimately, a case study is simply an interesting problem with many correct answers. What does case study work look like in classrooms? Teachers generally start by having students read the case or watch a video that summarizes the case. Students then work in small groups or individually to solve the case study. Teachers set milestones defining what students should accomplish to help them manage their time.

During the case study learning process, student assessment of learning should be focused on reflection. Arthur L. Costa and Bena Kallick’s Learning and Leading With Habits of Mind gives several examples of what this reflection can look like in a classroom:

Journaling: At the end of each work period, have students write an entry summarizing what they worked on, what worked well, what didn’t, and why. Sentence starters and clear rubrics or guidelines will help students be successful. At the end of a case study project, as Costa and Kallick write, it’s helpful to have students “select significant learnings, envision how they could apply these learnings to future situations, and commit to an action plan to consciously modify their behaviors.”

Interviews: While working on a case study, students can interview each other about their progress and learning. Teachers can interview students individually or in small groups to assess their learning process and their progress.

Student discussion: Discussions can be unstructured—students can talk about what they worked on that day in a think-pair-share or as a full class—or structured, using Socratic seminars or fishbowl discussions. If your class is tackling a case study in small groups, create a second set of small groups with a representative from each of the case study groups so that the groups can share their learning.

4 Tips for Setting Up a Case Study

1. Identify a problem to investigate: This should be something accessible and relevant to students’ lives. The problem should also be challenging and complex enough to yield multiple solutions with many layers.

2. Give context: Think of this step as a movie preview or book summary. Hook the learners to help them understand just enough about the problem to want to learn more.

3. Have a clear rubric: Giving structure to your definition of quality group work and products will lead to stronger end products. You may be able to have your learners help build these definitions.

4. Provide structures for presenting solutions: The amount of scaffolding you build in depends on your students’ skill level and development. A case study product can be something like several pieces of evidence of students collaborating to solve the case study, and ultimately presenting their solution with a detailed slide deck or an essay—you can scaffold this by providing specified headings for the sections of the essay.

Problem-Based Teaching Resources

There are many high-quality, peer-reviewed resources that are open source and easily accessible online.

The National Center for Case Study Teaching in Science at the University at Buffalo built an online collection of more than 800 cases that cover topics ranging from biochemistry to economics. There are resources for middle and high school students.
Models of Excellence , a project maintained by EL Education and the Harvard Graduate School of Education, has examples of great problem- and project-based tasks—and corresponding exemplary student work—for grades pre-K to 12.
The Interdisciplinary Journal of Problem-Based Learning at Purdue University is an open-source journal that publishes examples of problem-based learning in K–12 and post-secondary classrooms.
The Tech Edvocate has a list of websites and tools related to problem-based learning.

In their book Problems as Possibilities , Linda Torp and Sara Sage write that at the elementary school level, students particularly appreciate how they feel that they are taken seriously when solving case studies. At the middle school level, “researchers stress the importance of relating middle school curriculum to issues of student concern and interest.” And high schoolers, they write, find the case study method “beneficial in preparing them for their future.”

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Class 9 Science Case...

Class 9 Science Case Study Questions

Table of Contents

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Download the app to get CBSE Sample Papers 2023-24, NCERT Solutions (Revised), Most Important Questions, Previous Year Question Bank, Mock Tests, and Detailed Notes.

If you are wondering how to solve class 9 science case study questions, then myCBSEguide is the best platform to choose. With the help of our well-trained and experienced faculty, we provide solved examples and detailed explanations for the recently added Class 9 Science case study questions.

You can find a wide range of solved case studies on myCBSEguide, covering various topics and concepts. Class 9 Science case studies are designed to help you understand the application of various concepts in real-life situations.

The rationale behind Science

Science is crucial for Class 9 students’ cognitive, emotional, and psychomotor development. It encourages curiosity, inventiveness, objectivity, and aesthetic sense.

In the upper primary stage, students should be given a variety of opportunities to engage with scientific processes such as observing, recording observations, drawing, tabulating, plotting graphs, and so on, whereas in the secondary stage, abstraction and quantitative reasoning should take a more prominent role in science teaching and learning. As a result, the concept of atoms and molecules as matter’s building units, as well as Newton’s law of gravitation, emerges.

Science is important because it allows Class 9 Science students to understand the world around us. It helps to find out how things work and to find solutions to problems at the Class 9 Science level. Science is also a source of enjoyment for many people. It can be a hobby, a career, or a source of intellectual stimulation.

Case study questions in Class 9 Science

The inclusion of case study questions in Class 9 science CBSE is a great way to engage students in critical thinking and problem-solving. By working through real-world scenarios, Class 9 Science students will be better prepared to tackle challenges they may face in their future studies and careers. Class 9 Science Case study questions also promote higher-order thinking skills, such as analysis and synthesis. In addition, case study questions can help to foster creativity and innovation in students. As per the recent pattern of the Class 9 Science examination, a few questions based on case studies/passages will be included in the CBSE Class 9 Science Paper. There will be a paragraph presented, followed by questions based on it.

Examples of Class 9 science class case study questions

Class 9 science case study questions have been prepared by myCBSEguide’s qualified teachers. Class 9 case study questions are meant to evaluate students’ knowledge and comprehension of the material. They are not intended to be difficult, but they will require you to think critically about the material. We hope you find Class 9 science case study questions beneficial and that they assist you in your exam preparation.

The following are a few examples of Class 9 science case study questions.

Class 9 science case study question 1

due to its high compressibility
large volumes of a gas can be compressed into a small cylinder
transported easily
all of these
shape, volume
volume, shape
shape, size
size, shape
the presence of dissolved carbon dioxide in water
the presence of dissolved oxygen in the water
the presence of dissolved Nitrogen in the water
liquid particles move freely
liquid have greater space between each other
both (a) and (b)
none of these
Only gases behave like fluids
Gases and solids behave like fluids
Gases and liquids behave like fluids
Only liquids are fluids

Answer Key:

(d) all of these
(a) shape, volume
(b) the presence of dissolved oxygen in the water
(c) both (a) and (b)
(c) Gases and liquids behave like fluids

Class 9 science case study question 2

12/32 times
18 g of O 2
18 g of CO 2
18 g of CH 4
1 g of CO 2
1 g of CH 4 CH 4
2 moles of H2O
20 moles of water
6.022 × 1023 molecules of water
1.2044 × 1025 molecules of water
(I) and (IV)
(II) and (III)
(II) and (IV)
Sulphate molecule
Ozone molecule
Phosphorus molecule
Methane molecule
(c) 8/3 times
(d) 18g of CH 4
(c) 1g of H 2
(d) (II) and (IV)
(c) phosphorus molecule

Class 9 science case study question 3

collenchyma
chlorenchyma
It performs photosynthesis
It helps the aquatic plant to float
It provides mechanical support
Sclerenchyma
Collenchyma
Epithelial tissue
Parenchyma tissues have intercellular spaces.
Collenchymatous tissues are irregularly thickened at corners.
Apical and intercalary meristems are permanent tissues.
Meristematic tissues, in its early stage, lack vacuoles, muscles
(I) and (II)
(III) and (I)
Transpiration
Provides mechanical support
Provides strength to the plant parts
None of these
(a) Collenchyma
(b) help aquatic plant to float
(b) Sclerenchyma
(d) Only (III)
(c) provide strength to plant parts

Cracking Class 9 Science Case Study Questions

There is no one definitive answer to Class 9 Science case study questions. Every case study is unique and will necessitate a unique strategy. There are, nevertheless, certain general guidelines to follow while answering case study questions.

To begin, double-check that you understand the Class 9 science case study questions. Make sure you understand what is being asked by reading it carefully. If you’re unclear, seek clarification from your teacher or tutor.
It’s critical to read the Class 9 Science case study material thoroughly once you’ve grasped the question. This will provide you with a thorough understanding of the problem as well as the various potential solutions.
Brainstorming potential solutions with classmates or other students might also be beneficial. This might provide you with multiple viewpoints on the situation and assist you in determining the best solution.
Finally, make sure your answer is presented simply and concisely. Make sure you clarify your rationale and back up your claim with evidence.

A look at the Class 9 Science Syllabus

The CBSE class 9 science syllabus provides a strong foundation for students who want to pursue a career in science. The topics are chosen in such a way that they build on the concepts learned in the previous classes and provide a strong foundation for further studies in science. The table below lists the topics covered in the Class 9 Science syllabus of the Central Board of Secondary Education (CBSE). As can be seen, the Class 9 science syllabus is divided into three sections: Physics, Chemistry and Biology. Each section contains a number of topics that Class 9 science students must study during the course.

CBSE Class 9 Science (Code No. 086)

Theme: Materials Unit I: Matter-Nature and Behaviour Definition of matter; solid, liquid and gas; characteristics – shape, volume, density; change of state-melting (absorption of heat), freezing, evaporation (cooling by evaporation), condensation, sublimation. Nature of matter: Elements, compounds and mixtures. Heterogeneous and homogenous mixtures, colloids and suspensions. Particle nature and their basic units: Atoms and molecules, Law of constant proportions, Atomic and molecular masses. Mole concept: Relationship of mole to mass of the particles and numbers. Structure of atoms: Electrons, protons and neutrons, valency, the chemical formula of common compounds. Isotopes and Isobars.

Theme: The World of the Living Unit II: Organization in the Living World Cell – Basic Unit of life: Cell as a basic unit of life; prokaryotic and eukaryotic cells, multicellular organisms; cell membrane and cell wall, cell organelles and cell inclusions; chloroplast, mitochondria, vacuoles, endoplasmic reticulum, Golgi apparatus; nucleus, chromosomes – basic structure, number. Tissues, Organs, Organ System, Organism: Structure and functions of animal and plant tissues (only four types of tissues in animals; Meristematic and Permanent tissues in plants).

Theme: Moving Things, People and Ideas Unit III: Motion, Force and Work Motion: Distance and displacement, velocity; uniform and non-uniform motion along a straight line; acceleration, distance-time and velocity-time graphs for uniform motion and uniformly accelerated motion, derivation of equations of motion by graphical method; elementary idea of uniform circular motion. Force and Newton’s laws: Force and Motion, Newton’s Laws of Motion, Action and Reaction forces, Inertia of a body, Inertia and mass, Momentum, Force and Acceleration. Elementary idea of conservation of Momentum. Gravitation: Gravitation; Universal Law of Gravitation, Force of Gravitation of the earth (gravity), Acceleration due to Gravity; Mass and Weight; Free fall. Floatation: Thrust and Pressure. Archimedes’ Principle; Buoyancy. Work, energy and power: Work done by a Force, Energy, power; Kinetic and Potential energy; Law of conservation of energy. Sound: Nature of sound and its propagation in various media, speed of sound, range of hearing in humans; ultrasound; reflection of sound; echo.

Theme: Food Unit IV: Food Production Plant and animal breeding and selection for quality improvement and management; Use of fertilizers and manures; Protection from pests and diseases; Organic farming.

PRESCRIBED BOOKS:

Science-Textbook for class IX-NCERT Publication
Assessment of Practical Skills in Science-Class IX – CBSE Publication
Laboratory Manual-Science-Class IX, NCERT Publication
Exemplar Problems Class IX – NCERT Publication

myCBSEguide: A true helper

There are numerous advantages to using myCBSEguide to achieve the highest results in Class 9 Science.

myCBSEguide offers high-quality study materials that cover all of the topics in the Class 9 Science curriculum.
myCBSEguide provides practice questions and mock examinations to assist students in the best possible preparation for their exams.
On our myCBSEguide app, you’ll find a variety of solved Class 9 Science case study questions covering a variety of topics and concepts. These case studies are intended to help you understand how certain principles are applied in real-world settings
myCBSEguide is that the study material and practice problems are developed by a team of specialists who are always accessible to assist students with any questions they may have. As a result, students may be confident that they will receive the finest possible assistance and support when studying for their exams.

So, if you’re seeking the most effective strategy to study for your Class 9 Science examinations, myCBSEguide is the place to go!

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Case Study Questions of Chapter 3 Atoms and Molecules PDF Download

Case study Questions on Class 9 Science Chapter 3 are very important to solve for your exam. Class 9 Science Chapter 3 Case Study Questions have been prepared for the latest exam pattern. You can check your knowledge by solving case study-based questions for Class 9 Science Chapter 3 Atoms and Molecules

Atoms and Molecules Case Study Questions With answers

Here, we have provided case-based/passage-based questions for Class 9 Science Chapter 3 Atoms and Molecules

Case Study/Passage Based Questions

The knowledge of valencies of various radicals helps us to write the formulae of chemical compounds. The total positive charge on positive ions (cations) is equal to the total negative charge on negative ions (anions) in a molecule. Therefore, in writing the formula of a compound, the positive and negative ions are adjusted in such a way that the total number of positive charges of positive ions (cations) becomes equal to the total number of negative charges of negative ions (anions). There is another simple method for writing the formulae of ionic compounds. In this method, the valencies (or positive or negative charges) of the ions can be ‘crossed over’ to give subscripts. The purpose of crossing over of charges is to find the number of ions required to equalise the number of positive and negative charges.

Answer: (d) nitrogen and iron.

The formula of the sulphate of an element X is X 2 (SO 4 ) 3 . The formula of nitride of element X will be (a) X 2 N (b) XN 2 (c) XN (d) X 2 N 3

Answer: (c) XN

The formula of a compound is X 3 Y. The valencies of elements X and Y will be respectively (a) 1 and 3 (b) 3 and 1 (c) 2 and 3 (d) 3 and 2

Answer: (a) 1 and 3

A mole of an atom is a collection of atoms whose total mass is the number of grams equal to the atomic mass. Since an equal number of moles of different elements contain an equal number of atoms it becomes convenient to express the amounts of the elements in terms of moles. A mole represents a definite number of particles viz, atoms, molecules, ions or electrons. This definite number is called the Avogadro number or Avogadro constant which is equal to 6.022 × 1023. Hence a mole represents 6.022 × 1023 particles of the substance. One mole of a substance represents one gram-formula of the substance. One mole of a gas at standard temperature and pressure occupies 22.4 litres.

How many grams of sodium must be taken to get 1 mole of the element? (a) 23 g (b) 35.5 g (c) 63.5 g (d) 46 g

Answer: (a) 23 g

What is the mass in grams of a single atom of chlorine? (Atomic mass of chlorine = 35.5) (a) 6.54 × 10 23 g (b) 5.9 × 10 –23 g (c) 0.0025 g (d) 35.5 g

Answer: (b) 5.9 × 10–23 g

How many number of moles are there in 5.75 g of sodium ? (Atomic mass of sodium = 23) (a) 0.25 (b) 0.5 (c) 1 (d) 2.5

Answer: (a) 0.25

What is the mass in grams of 2.42 mol of zinc? (Atomic mass of Zn = 65.41) (a) 200 g (b) 25 g (c) 85 g (d) 158 g

Answer: (d) 158 g

According to Dalton’s atomic theory, all matter whether an element, a compound, or a mixture is composed of small particles called atoms which can neither be created nor destroyed during a chemical reaction. Dalton’s theory provides a simple explanation for the laws of chemical combination. He used his theory to explain the law of conservation of masses, the law of constant proportions, and the law of multiple proportions, based on various postulates of the theory. Dalton was the first scientist to use the symbols for the elements in a very specific sense. When he used a symbol for an element he also meant a definite quantity of that element, that is one atom of that element.

Answer: (a) Atoms can neither be created nor destroyed.

Answer: (b) An element consists of atoms having fixed mass and the number and kind of atoms in a given compound is fixed.

Answer: (b) Law of conservation of mass

Answer: (c) Law of constant proportions

Hope the information shed above regarding Case Study and Passage Based Questions for Class 9 Science Chapter 3 Atoms and Molecules with Answers Pdf free download has been useful to an extent. If you have any other queries of CBSE Class 9 Science Atoms and Molecules Case Study and Passage Based Questions with Answers, feel free to comment below so that we can revert back to us at the earliest possible

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Case Study Chapter 3 Metals and Non-Metals

Please refer to Chapter 3 Metals and Non-Metals Case Study Questions with answers provided below. We have provided Case Study Questions for Class 10 Science for all chapters as per CBSE, NCERT and KVS examination guidelines. These case based questions are expected to come in your exams this year. Please practise these case study based Class 10 Science Questions and answers to get more marks in examinations.

Case Study Questions Chapter 3 Metals and Non-Metals

Case/Passage – 1

Metals are electropositive elements. They can easily lose electrons to form ions. Metals show distinguished physical as well as chemical properties. Generally most of the metals are ductile and malleable with exception such as mercury. These properties make them valuable for commercial as well as domestic uses. Reaction of a metal with water is one of important chemical property. Metals like sodium and potassium reacts with cold water while magnesium reacts with hot water. Metals like aluminium, zinc do not react with hot/cold water but they easily react with steam. When a metal react with hot/cold water the products are metal hydroxide and hydrogen,and when it react with steam, the product are metal oxide and hydrogen. Some metals like sodium, potassium react violently with water.

Question: When zinc reacts with steam it produces: (a) Zn(OH) 2 (b) ZnO (c) O 2 (d) ZnO 2

Question: During the reaction of calcium with water, pieces of metal start floating due to the formation of: (a) Ca(OH) 2 (b) CO2 (c) H 2 (d) none of these

Question: Consider the reactions: Na(s) + H 2 O (l) → NaOH (aq) + H2 (g) ……….(i) Ca(s) + H 2 O (l) → Ca(OH) 2 (aq) + H 2 (g) ………(ii) (a) Reaction (i) is endothermic reaction. (b) Reaction (ii) is endothermic reaction. (c) Reaction (ii) is more exothermic than reaction (i). (d) Reaction (i) is more exothermic than reaction (ii).

Question: Most ductile metal among the following is: (a) Au (b) Ag (c) Cu (d) Al

Question: Metals can be converted into thin sheet by hammering.This property is known as: (a) Ductility (b) Sonorous (c) Malleability (d) Both (a) and (c)

Case/Passage – 2

Elements can be classified as metals or non-metals on the basis of their properties. The easiest way to start grouping substances is by comparing their physical properties. Metals, in their pure state, have a shining surface. This property is called metallic luster. metals are generally hard. The hardness varies from metal to metal. some metals are used for making cooking vessels.

Question: The most abundant metal in the earth’s crust is – (a) iron (b) copper (c) aluminium (d) mercury

Question: The metal that reacts with cold water is – (a) mercury (b) sodium (c) zinc (d)tungsten

Question: Metal present in chloroplast is (a) Iron (b) Copper (c) Magnesium (d) Cobalt

Question: Metals generally are (a) reducing agents (b) oxidising agent (c) both oxidising and reducing agents (d) None of these

Question: Which of the following metal(s) catch fire on reaction with water? (a) Sodium (b) Potassium (c) Magnesium (d) both (a) and (b)

Case/Passage – 3

The huge annual loss due to corrosion is a national waste and should be minimized. Following are some methods which are helpful to prevent corrosion

(i) Coating the iron surface with paint or oil or grease prevents moist oxygen from coming in contact with the metal and thus effectively prevents rusting of iron. (ii) Galvanisation : Iron is blasted with fine sand to make the surface rough dipped in molten zinc and then cooled. A thin layer of zinc forms on the iron surface. Since zinc is more reactive than iron, it acts as a sacrificial metal and is preferentially oxidised thus preventing oxidation of iron. (iii) Electroplating with tin, nickel or chromium also prevents rusting. (iv) Alloying (mixing iron in its molten state with other metals) prevents rusting. Stainless steel is an alloy of iron with Cr or Ni.

Question: The most convenient method to protect the bottom of ship made of iron is : (a) coating it with red lead oxide. (b) white tin plating. (c) connecting it with Mg block. (d) connecting it with Pb block.

Question: The best way to prevent rusting of iron is : (a) making it cathode (b) putting in saline water (c) both of these (d) none of these

Question: The most durable metal plating on iron to protect against corrosion is : (a) nickel plating (b) copper plating (c) tin plating (d) zinc plating

Case/Passage – 4

Some metals are chemically very reactive, whereas others are less reactive or unreactive. On the basis of vigourness of reactions of various metals with oxygen, water and acids, as well as displacement reactions, the metals have been arranged in a group or series according to their chemical reactivity. The arrangement of metals in a vertical column in the order of decreasing reactivities is called reactivity series of metals (or activity series of metals). In reactivity series, the most reactive metal is placed at the top whereas the least reactive metal is placed at the bottom. As we come down in the series, the chemical reactivity of metals decreases. Since the metals placed at the bottom of the reactivity series (like silver and gold) are less reactive, so they are usually found in free state (native state) in nature.

Question: Copper sulphate solution can be safely kept in a container made of : (a) aluminium (b) lead (c) silver (d) zinc

Question: When metal Z is added to dilute HCl solution, there is no evolution of gas. Metal is : (a) K (b) Na (c) Ag (d) Zn

Question: Metal always found in free state is : (a) gold (b) silver (c) copper (d) sodium

Case Study Chapter 3 Metals and Non-Metals

Class 10 maths all formulas.

Heredity And Evolution Class 10 Science Notes And Questions

Acids Bases Salts Class 10 Science Notes And Questions

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Cbse class 12 toppers list 2024: check toppers' names, districts, marks, rank list and other details here.

CBSE Class 12 Toppers list 2024: The CBSE has released the eagerly awaited class 12 board results today, available on cbse.gov.in. Over 24,000 students scored above 95%, with more than 1.16 lakh above 90%. Last year's toppers achieved remarkable percentages, with Aadarsh Kumar Singh and Srikrishna Sathyajeeth leading. Approximately 39 lakh students participated in this year's Class 10th and 12th exams, with results accessible online through various platforms.

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Study Suggests Genetics as a Cause, Not Just a Risk, for Some Alzheimer’s

People with two copies of the gene variant APOE4 are almost certain to get Alzheimer’s, say researchers, who proposed a framework under which such patients could be diagnosed years before symptoms.

A colorized C.T. scan showing a cross-section of a person's brain with Alzheimer's disease. The colors are red, green and yellow.

By Pam Belluck

Scientists are proposing a new way of understanding the genetics of Alzheimer’s that would mean that up to a fifth of patients would be considered to have a genetically caused form of the disease.

Currently, the vast majority of Alzheimer’s cases do not have a clearly identified cause. The new designation, proposed in a study published Monday, could broaden the scope of efforts to develop treatments, including gene therapy, and affect the design of clinical trials.

It could also mean that hundreds of thousands of people in the United States alone could, if they chose, receive a diagnosis of Alzheimer’s before developing any symptoms of cognitive decline, although there currently are no treatments for people at that stage.

The new classification would make this type of Alzheimer’s one of the most common genetic disorders in the world, medical experts said.

“This reconceptualization that we’re proposing affects not a small minority of people,” said Dr. Juan Fortea, an author of the study and the director of the Sant Pau Memory Unit in Barcelona, Spain. “Sometimes we say that we don’t know the cause of Alzheimer’s disease,” but, he said, this would mean that about 15 to 20 percent of cases “can be tracked back to a cause, and the cause is in the genes.”

The idea involves a gene variant called APOE4. Scientists have long known that inheriting one copy of the variant increases the risk of developing Alzheimer’s, and that people with two copies, inherited from each parent, have vastly increased risk.

The new study , published in the journal Nature Medicine, analyzed data from over 500 people with two copies of APOE4, a significantly larger pool than in previous studies. The researchers found that almost all of those patients developed the biological pathology of Alzheimer’s, and the authors say that two copies of APOE4 should now be considered a cause of Alzheimer’s — not simply a risk factor.

The patients also developed Alzheimer’s pathology relatively young, the study found. By age 55, over 95 percent had biological markers associated with the disease. By 65, almost all had abnormal levels of a protein called amyloid that forms plaques in the brain, a hallmark of Alzheimer’s. And many started developing symptoms of cognitive decline at age 65, younger than most people without the APOE4 variant.

“The critical thing is that these individuals are often symptomatic 10 years earlier than other forms of Alzheimer’s disease,” said Dr. Reisa Sperling, a neurologist at Mass General Brigham in Boston and an author of the study.

She added, “By the time they are picked up and clinically diagnosed, because they’re often younger, they have more pathology.”

People with two copies, known as APOE4 homozygotes, make up 2 to 3 percent of the general population, but are an estimated 15 to 20 percent of people with Alzheimer’s dementia, experts said. People with one copy make up about 15 to 25 percent of the general population, and about 50 percent of Alzheimer’s dementia patients.

The most common variant is called APOE3, which seems to have a neutral effect on Alzheimer’s risk. About 75 percent of the general population has one copy of APOE3, and more than half of the general population has two copies.

Alzheimer’s experts not involved in the study said classifying the two-copy condition as genetically determined Alzheimer’s could have significant implications, including encouraging drug development beyond the field’s recent major focus on treatments that target and reduce amyloid.

Dr. Samuel Gandy, an Alzheimer’s researcher at Mount Sinai in New York, who was not involved in the study, said that patients with two copies of APOE4 faced much higher safety risks from anti-amyloid drugs.

When the Food and Drug Administration approved the anti-amyloid drug Leqembi last year, it required a black-box warning on the label saying that the medication can cause “serious and life-threatening events” such as swelling and bleeding in the brain, especially for people with two copies of APOE4. Some treatment centers decided not to offer Leqembi, an intravenous infusion, to such patients.

Dr. Gandy and other experts said that classifying these patients as having a distinct genetic form of Alzheimer’s would galvanize interest in developing drugs that are safe and effective for them and add urgency to current efforts to prevent cognitive decline in people who do not yet have symptoms.

“Rather than say we have nothing for you, let’s look for a trial,” Dr. Gandy said, adding that such patients should be included in trials at younger ages, given how early their pathology starts.

Besides trying to develop drugs, some researchers are exploring gene editing to transform APOE4 into a variant called APOE2, which appears to protect against Alzheimer’s. Another gene-therapy approach being studied involves injecting APOE2 into patients’ brains.

The new study had some limitations, including a lack of diversity that might make the findings less generalizable. Most patients in the study had European ancestry. While two copies of APOE4 also greatly increase Alzheimer’s risk in other ethnicities, the risk levels differ, said Dr. Michael Greicius, a neurologist at Stanford University School of Medicine who was not involved in the research.

“One important argument against their interpretation is that the risk of Alzheimer’s disease in APOE4 homozygotes varies substantially across different genetic ancestries,” said Dr. Greicius, who cowrote a study that found that white people with two copies of APOE4 had 13 times the risk of white people with two copies of APOE3, while Black people with two copies of APOE4 had 6.5 times the risk of Black people with two copies of APOE3.

“This has critical implications when counseling patients about their ancestry-informed genetic risk for Alzheimer’s disease,” he said, “and it also speaks to some yet-to-be-discovered genetics and biology that presumably drive this massive difference in risk.”

Under the current genetic understanding of Alzheimer’s, less than 2 percent of cases are considered genetically caused. Some of those patients inherited a mutation in one of three genes and can develop symptoms as early as their 30s or 40s. Others are people with Down syndrome, who have three copies of a chromosome containing a protein that often leads to what is called Down syndrome-associated Alzheimer’s disease .

Dr. Sperling said the genetic alterations in those cases are believed to fuel buildup of amyloid, while APOE4 is believed to interfere with clearing amyloid buildup.

Under the researchers’ proposal, having one copy of APOE4 would continue to be considered a risk factor, not enough to cause Alzheimer’s, Dr. Fortea said. It is unusual for diseases to follow that genetic pattern, called “semidominance,” with two copies of a variant causing the disease, but one copy only increasing risk, experts said.

The new recommendation will prompt questions about whether people should get tested to determine if they have the APOE4 variant.

Dr. Greicius said that until there were treatments for people with two copies of APOE4 or trials of therapies to prevent them from developing dementia, “My recommendation is if you don’t have symptoms, you should definitely not figure out your APOE status.”

He added, “It will only cause grief at this point.”

Finding ways to help these patients cannot come soon enough, Dr. Sperling said, adding, “These individuals are desperate, they’ve seen it in both of their parents often and really need therapies.”

Pam Belluck is a health and science reporter, covering a range of subjects, including reproductive health, long Covid, brain science, neurological disorders, mental health and genetics. More about Pam Belluck

The Fight Against Alzheimer’s Disease

Alzheimer’s is the most common form of dementia, but much remains unknown about this daunting disease..

How is Alzheimer’s diagnosed? What causes Alzheimer’s? We answered some common questions .

A study suggests that genetics can be a cause of Alzheimer’s , not just a risk, raising the prospect of diagnosis years before symptoms appear.

Determining whether someone has Alzheimer’s usually requires an extended diagnostic process . But new criteria could lead to a diagnosis on the basis of a simple blood test .

The F.D.A. has given full approval to the Alzheimer’s drug Leqembi. Here is what to know about i t.

Alzheimer’s can make communicating difficult. We asked experts for tips on how to talk to someone with the disease .

Open access
Published: 14 May 2024

Quantitative evaluation of vertical control in orthodontic camouflage treatment for skeletal class II with hyperdivergent facial type

Yan-Ning Guo 1 , 2 na1 ,
Sheng-Jie Cui 1 na1 ,
Jie-Ni Zhang 1 ,
Yan-Heng Zhou 1 &
Xue-Dong Wang 1

Head & Face Medicine volume 20 , Article number: 31 ( 2024 ) Cite this article

Metrics details

In this study, we sought to quantify the influence of vertical control assisted by a temporary anchorage device (TAD) on orthodontic treatment efficacy for skeletal class II patients with a hyperdivergent facial type and probe into the critical factors of profile improvement.

A total of 36 adult patients with skeletal class II and a hyperdivergent facial type were included in this retrospective case–control study. To exclude the effect of sagittal anchorage reinforcement, the patients were divided into two groups: a maxillary maximum anchorage (MMA) group ( N = 17), in which TADs were only used to help with anterior tooth retraction, and the MMA with vertical control (MMA + VC) group ( N = 19), for which TADs were also used to intrude the maxillary molars and incisors. The treatment outcome was evaluated using dental, skeletal, and soft-tissue-related parameters via a cephalometric analysis and cast superimposition.

A significant decrease in ANB ( P < 0.05 for both groups), the retraction and uprighting of the maxillary and mandibular incisors, and the retraction of protruded upper and lower lips were observed in both groups. Moreover, a significant intrusion of the maxillary molars was observed via the cephalometric analysis (− 1.56 ± 1.52 mm, P < 0.05) and cast superimposition (− 2.25 ± 1.03 mm, P < 0.05) of the MMA + VC group but not the MMA group, which resulted in a remarkable decrease in the mandibular plane angle (− 1.82 ± 1.38°, P < 0.05). The Z angle (15.25 ± 5.30°, P < 0.05) and Chin thickness (− 0.97 ± 0.45°, P < 0.05) also improved dramatically in the MMA + VC group, indicating a better profile and a relaxed mentalis. Multivariate regression showed that the improvement in the soft tissue was closely related to the counterclockwise rotation of the mandible plane ( P < 0.05).

Conclusions

TAD-assisted vertical control can achieve intrusion of approximately 2 mm for the upper first molars and induce mandibular counterclockwise rotation of approximately 1.8°. Moreover, it is especially important for patients without sufficient retraction of the upper incisors or a satisfactory chin shape.

Peer Review reports

For adult patients with severe class II malocclusion accompanied by a hyperdivergent growth pattern, orthognathic surgery is usually the optimal therapy to improve facial aesthetics and masticatory function [ 1 , 2 ]. Nevertheless, some patients refuse surgery due to its possible risks and high cost. Orthodontic camouflage treatment provides an alternative for such patients [ 3 , 4 ].

To improve the profile of this kind of patient, both sagittal retraction and vertical control are important. Several studies have found and confirmed the importance of vertical control in orthodontic treatment for skeletal class II malocclusion [ 5 , 6 , 7 ]. However, varying treatment methods are used. For adolescent patients, the most effective approach is often to utilize their vertical growth potential to guide their facial development in the desired direction. Jamilian et al. applied a modified functional orthodontic appliance to induce sagittal and vertical changes in the mandible, achieving significant facial improvement for a patient with severe skeletal class II [ 8 ].

On the other hand, for adult patients lacking growth potential, active intrusion of posterior teeth is required to intervene vertically. Early on, high-pull headgear was the most common vertical control method, but this approach relied heavily on patient compliance, and it involved the application of intermittent force, making it relatively unreliable [ 9 , 10 , 11 ].

TADs’ emergence has greatly improved the convenience and efficiency of treatment [ 12 , 13 ]. Compared to headgear, TAD-assisted vertical control can provide more dental intrusion and counterclockwise rotation of the mandibular plane, which contributes to further improvement of profile [ 14 , 15 ]. Additionally, when active intrusion was applied, we typically utilize a sustained light force (approximately 50 g), which is more favorable for the remodeling of periodontal tissues compared to the intermittent heavy force exerted by headgear.

However, the mini-implants placed in the maxilla’s posterior region can also provide strong sagittal anchorage. Several studies have shown that maximum anchorage itself can achieve a better treatment outcome and improve the profile [ 16 , 17 , 18 ]. These findings have prompted the following questions: If sagittal retraction can already lead to sufficient facial aesthetics, is vertical tooth movement still necessary? To what extent can vertical movements benefit the facial profile?

Our research group has paid close attention to the efficacy of TAD-assisted vertical control in orthodontic camouflage treatments for patients with skeletal class II malocclusion. We have published several case reports and long-term follow-up studies showing that vertical control significantly improved the profiles of patients with skeletal class II malocclusion and a hyperdivergent facial type, achieving good long-term stability [ 19 , 20 , 21 , 22 , 23 ]. We believe that specifying how the active intrusion of upper dentition contributes to these craniofacial improvements will provide more information about the ability and limits of TAD-assisted vertical control and broaden the understanding of orthodontic camouflage treatment. Therefore, we included a control group whose TADs were used only to reinforce maxillary sagittal anchorage in order to exclude the influence of sagittal retraction.

With this retrospective case–control study, we aimed to quantify the effectiveness of TAD-assisted vertical control in the improvement of dentoalveolar malformation and soft tissue profiles in adult patients with a severe skeletal class II hyperdivergent pattern, and justified the necessity of active intrusion. We believe that this article provides specific references for orthodontists and general dentists concerning the camouflage treatment of patients with skeletal class II malocclusion.

This study was based on retrospective data obtained from orthodontic records at the Peking University School and Hospital of Stomatology, and it was approved by the institution’s biomedical ethics committee (approval number: PKUSSIRB-201630096, retrospectively registered). The patients included in this study accepted orthodontic treatment between 2006 and 2018.

The study’s sample selection was based on the following inclusion criteria: good-quality orthodontic records, the presence of permanent dentition, age > 18 years, a convex profile, skeletal class II (ANB > 5°), and a hyperdivergent skeletal pattern (FMA > 28°) [ 24 ]. The exclusion criteria included the following: dental anomalies in size, number, shape, or structure; permanent tooth loss; orthodontic–orthognathic combined surgery treatment; and Botox injection or prosthesis implantation before or during orthodontic treatment.

Treatment protocols

All the participants underwent systematic periodontal and endodontic assessments and therapies before orthodontic interventions. A straight-wire MBT technique was utilized after the extraction of four premolars from all patients. Braces and archwires were obtained from TP Orthodontics (La Porte, IN, USA). The alignment and leveling phases involved initial bracket-bonding followed by a certain procedure utilizing 0.014 in. NiTi, 0.016 in. NiTi, 0.016 in. × 0.022 in. NiTi, and 0.019 in. × 0.025 in. NiTi archwires sequentially. During the space-closing phase, a 0.019 × 0.025 in. stainless steel archwire was applied using a conventional sliding mechanism. This phase was terminated upon the complete closure of the premolar spaces. The patients’ dentition was finely adjusted before debonding. Miniscrews (diameter: 1.5 mm; length: 7 mm; Zhongbang Medical Treatment Appliance, Xi’an, China) were surgically inserted into the alveolar ridge.

The patients were divided into two groups: (1) the maxillary maximum anchorage (MMA) group, in which TADs were implanted only at the bilateral buccal side of the alveolar bone, between the roots of the upper premolar and the upper first molar or between the upper first molar and the upper second molar; and (2) the maxillary maximum anchorage with vertical control (MMA + VC) group, in which TADs were implanted into the bilateral buccal and lingual sides of the alveolar bone, between the roots of the upper first molar and the upper second molar, to intrude the upper molars with or without the TADs implanted in the anterior segment for incisor intrusion (Fig. 1 ).

Representative image of intraoral devices. A . TAD-assisted intrusion of the upper anterior teeth. B . Buccal view of the posterior intrusion devices. C . Palatal view of the posterior intrusion devices

Sample size calculation

In this study, the effect size of the primary outcome was expected to be 2.32. This number was the difference in mandibular counterclockwise rotation (the decrease in the FMA value) between the two groups calculated in our preliminary study. The sample size was calculated using online software ( http://hedwig.mgh.harvard.edu/sample_size/ ) by assuming 5% type I errors and 20% type II errors. The sample calculation indicated that at least 10 patients were needed in each group.

In total, 36 patients were selected for the current study. The MMA group comprised 17 patients (14 females, 3 males) with a mean age of 24.18 ± 3.83 years and a mean treatment duration of 34.4 ± 12.8 months. The MMA + VC group consisted of 19 patients (16 females, 3 males) aged 25.00 ± 4.99 years, whose mean treatment duration was 34.7 ± 6.8 months. No significant difference in the patients’ gender, age, or treatment duration was observed between the groups (Additional Table 1 ).

Cephalometric analysis

Pre-treatment and post-treatment lateral cephalograms were collected, digitized, and superimposed using the Dolphin 11.0 software (Dolphin Imaging, Chatsworth, CA). An investigator who was not informed about the study’s groups obtained the measurements, which a second blinded investigator checked for accuracy. Any disagreements between these investigators were resolved through a weighted reevaluation until they were both satisfied. The variables used in the cephalometric analysis included skeletal, dental, and soft-tissue-related measurements. In total, 29 such variables were used (8 skeletal, 12 dental, and 9 soft-tissue-related). Figure 2 depicts the landmarks and important variables used in this study, while Additional Table 2 provides definitions.

Tracing of a pretreatment cephalometric radiograph

Dental cast analysis

Pre-treatment and post-treatment dental casts were scanned using a 3Shape scanner (3Shape D, Kopenhagen, Dänemark) and measured in a double-blinded manner by a trained orthodontist using the Geomagic 13.0 software (Geomagic Qualify, Durham, NC, US). As Fig. 3 shows, the superimposition of the dental casts was based on the palate’s stable structure. A coordinate system was built, based on the definition of the anatomical occlusal plane and the midline of the palate. The tooth movements were analyzed in two dimensions, anterior or posterior (X) and intrusion or extrusion (Z). Additionally, posterior and extrusive movement was defined as positive.

Superimposition of the dental casts. A . The pre-treatment maxillary model. B . The post-treatment maxillary model. C . Superimposition based on the stable structure of the palate. D . Transfer of corresponding landmarks

To evaluate the method’s error, 10 post-treatment lateral cephalograms and digital casts were randomly selected and remeasured by the same examiners two weeks after the first measurement was obtained. The intraclass correlation coefficient (ICC) was used to assess intra-examiner reliability and the reproducibility of all linear and angular measurements.

Statistical analysis

The intraclass correlation efficient (ICC) was evaluated using a two-way random model. Descriptive statistics for the dental casts and radiographic measurements were calculated for both the first and second measurements. Comparisons were performed and correlations were identified using Student’s t test in accordance with the results of Shapiro–Wilk normality tests. The pre-treatment skeletal, dental, and soft-tissue-related variables were compared between the groups using independent-sample t tests. The same variables were also compared from pre-treatment to post-treatment using paired t tests. The differences in treatment changes (concerning both the lateral cephalograms and the dental casts) between the MMA and MMA + VC groups were evaluated using independent-sample t tests. Multiple linear regression analysis was used to test the correlation between the independent variables of craniofacial structures and the dependent variable, the Z angle. Both groups’ differences in treatment changes were normalized to the mean variance. Then, a backward method was used to screen the independent variables. The entry probability of F was 0.05, and the removal criterion was 0.1. The statistical tests were performed with SPSS 18.0 software (IBM Corp., Armonk, NY). The results were considered statistically significant at P < 0.05.

The groups were similar in age at the beginning of the orthodontic treatment (Additional Table 1 ). ICC was calculated with good reproducibility of the measurements (0.810–0.997), as Additional Table 3 shows.

The two groups showed similar mandibular retrognathia and hyperdivergent skeletal patterns. However, differences were observed in several variables, such as the Z angle, ANB, and L1-NB (mm). These differences indicated that the patients in the MMA + VC group had a more convex profile and more severe malocclusion (Table 1 ).

TAD-assisted vertical control better improved patients’ profiles

TADs’ efficacy in improving therapeutic outcomes is certain. However, whether and to what extent TAD-assisted vertical control can help patients with skeletal class II achieve better results from camouflage orthodontic treatments compared to the simple reinforcement of the maxillary anchorage is unclear.

For most of the patients whose results we recorded, a convex profile was the main complaint. Therefore, we first analyzed the improvements in soft-tissue-related variables for both groups (Tables 2 and 3 ). We discovered a similar trend of lip retraction (the UL-SnV angle and distance and the LL-SnV distance) and soft tissue relaxation (UL thickness and LL thickness). However, the change in the Z angle and Chin thickness showed that patients in the MMA + VC group experienced more improvement in their profiles and mentalis relaxation. (Figures 4 and 5 show the representative cases of the two groups, respectively.) Through these results, we have shown that TAD-assisted vertical control further improved the patients’ profiles, but how this advantage was achieved remained unclear.

A representative case from the MMA group. The upper anterior incisors were restored using a ceramic veneer

A representative case from the MMA + VC group

TAD-assisted vertical control contributed to maxillary retraction and mandibular counterclockwise rotation

Remarkable decreases in SNA and ANB were discovered in both groups. Furthermore, the decrease in ANB in the MMA + VC group was significantly greater compared to MMA group, showing effective maxillary retraction, which partly explained the dramatic change in the soft tissue (Tables 4 and 5 ).

Additionally, no significant differences in the mandibular plane angle in the MMA group pre- and post-treatment were observed. Indeed, the lower facial height (ANS-Me) even increased slightly. Meanwhile, the MP-SN and FMA values significantly decreased in the MMA + VC group, suggesting that TAD-assisted vertical control effectively achieved mandibular counterclockwise rotation. The decrease in the mandibular plane angle showed a significant difference in the MP-SN and FMA values between the MMA and MMA + VC groups (Table 5 ). An emphatic change was also observed in the improvement of PFH/AFH, indicating an improvement in the hyperdivergent facial type. Thus, the application of TAD-assisted vertical control achieved a certain extent of mandibular counterclockwise rotation, which also helped improve patients’ profiles (Fig. 6 ).

Schematic graph of TAD-assisted vertical control during orthodontic camouflage treatment for patients with skeletal class II and a hyperdivergent facial type

TADs achieved substantial vertical control via the intrusion of maxillary dentition

Despite the gratifying sagittal retraction of the incisors in both groups (Table 6 ), the study’s cephalometric analysis showed significant intrusion of the upper molar on the P-P plane (U6-PP) in the MMA + VC group but not in the MMA group. Similarly, the upper incisor showed more intrusion (U1-PP) in the MMA + VC group, though no significance was observed (Table 7 ). These results were confirmed via dental cast superimposition (Table 8 ). Compared to the MMA group, the MMA + VC group experienced significant intrusion of the upper dentition. However, our cephalometric analysis also revealed a significantly lower molar extrusion (L6-MP) on the mandibular plane in both groups during orthodontic treatment. Thus, the tooth movement in the vertical dimension manifested the intrusion of the upper dentition for the MMA + VC group and the extrusion of the lower molars for both groups.

Multivariate regression analysis revealed the key factors of profile improvement

Since the changes occurred at the same time, assessing which factors played the most important role in altering the patients’ soft tissue profile was difficult. Therefore, we selected the Z angle—one of the most representative and remarkably changed profile indicators—as the dependent variable for our analysis, and we conducted multiple linear regression of the standardized bone, tooth, and soft tissue measurements.

Considering the interference of collinearity, we selected the following representative indicators: ANB, MP-SN, PFH/AFH, U1/SN, IMPA, U1-PP, U6-PP, L1-MP, L6-MP, Pog-NB, UL thickness, LL thickness, and Chin thickness.

The results showed that Y = 0.000576 − 0.416 a − 0.340 b + 0.403 c (where Y denotes the Z angle and a , b , and c represent the MP-SN, U1-SN, and Pog-NB, respectively; Table 9 ). This finding indicated that the change in the Z angle was negatively correlated with the MP-SN and U1-SN variables and positively correlated with Pog-NB.

Thus, the gratifying profile improvement of patients with skeletal class II and the hyperdivergent facial type relied on the massive retraction of the upper incisors, the shape of the chin, and the mandibular plane’s counterclockwise rotation.

The efficacy of TAD-assisted vertical control

In this retrospective study, we endeavored to quantify the efficacy of TAD-facilitated vertical control in managing maxillary dental intrusion and consequent mandibular counterclockwise rotation. Subsequently, we elucidated their pivotal roles in enhancing soft tissue profiles according to the baseline of MMA group.

Evaluation of hard tissue showed that following en-masse retraction with mini-implants anchorage, the MMA group exhibited slight upper molar intrusion (U6: -0.86 ± 0.89 mm) and mandibular counterclockwise rotation (MP-SN: -0.16 ± 1.05°). This result is consistent with the randomized controlled trial conducted by Al-Sibale et al. [ 25 ] and the controlled clinical trial conducted by Chen et al. [ 14 ], suggesting that TADs in the maxillary alveolar can provide some vertical force even during sagittal retraction, necessitating attention to the direction of traction and the vertical position of the anterior teeth to avoid deepening of the overbite. Following active maxillary dental intrusion, the MMA + VC group exhibited greater upper molar intrusion (U6: -2.25 ± 1.03 mm) and mandibular counterclockwise rotation (MP-SN: -1.82 ± 1.38°), which is slightly lower than that reported by Ding et al. [ 15 ] and Deguchi et al. [ 26 ] This difference may be attributed to differences in inclusion criteria. In Ding’s study, the inclusion criteria were shallow overbite, while in Deguchi’s study were open bite. In contrast, our study included many patients with normal or even deep overbite. To achieve a favorable overbite after treatment, we conducted intrusion of not only molars but also anterior teeth (U1: -1.30 ± 1.61 mm; U3: -1.81 ± 1.28 mm) with the help of TADs in the anterior segment, which represented a more challenging improvement compared to the aforementioned studies.

In terms of soft tissue evaluation, many previous studies have discussed the main factors contributing to changes in various soft tissue landmarks. For instance, Maetevorakul et al. found that the improvement in incisor angle was most crucial for enhancing lower lip prominence, and the mandibular plane angle as well as different treatment modalities had significant effects on changes of soft tissue chin prominence [ 27 ]. Regarding the overall assessment of soft tissue profiles, Zhao et al. demonstrated that the Z angle had the best discriminative ability for female adults with Angle Class II Division 1 malocclusion [ 28 ]. Therefore, in this study, we stressed on the Z angle and found that the MMA + VC group showed a more significant improvement compared to the MMA group (15.25 ± 5.30° in the MMA + VC group; 10.54 ± 5.11° in the MMA group, P = 0.011), which correlates with the poorer profiles before treatment in the MMA + VC group. To better identify which patients require active dental intrusion, we conducted a multiple linear regression analysis and found that this improvement was most closely associated with the retraction of the upper anterior teeth, prominence of the pogonion, and counterclockwise rotation of the mandibular plane. Therefore, we can conclude that vertical control is more necessary for patients with limited space for retraction or poor chin morphology.

Limitations and prospects of TAD-assisted vertical control

Although the occlusal plane’s counterclockwise rotation is considered an effective method to reduce the angle of the mandibular plane [ 29 ], in the current study, we observed a trend of clockwise rotation. However, this unexpected result is consistent with the findings of many similar studies in this field [ 12 , 13 ]. We speculate that this rotation results from the pendulum effect of the upper anterior teeth. Compared with the molars, the upper incisors have less intrusion, suggesting that we must pay particular attention to controlling the occlusal plane.

Additionally, despite TADs’ advantages of simplicity, flexibility, and independence from patient cooperation, they remain an invasive treatment [ 30 , 31 ]. In the current study, however, six miniscrews were needed to achieve effective vertical control. This approach does not apply to patients with improper bone conditions, and it also increases the difficulty of operation. Therefore, we hope to develop further methods that are more convenient and minimally invasive. The use of midpalatal miniscrews and personalized palatal bars may be an alternative option [ 12 ]; however, such an approach would still pose challenges in terms of operation and hygiene maintenance. Accordingly, we hope to further reduce orthodontic devices’ complexity in order to meet the requirements of comfortable treatment.

Methodologically, the current study’s evaluation of muscle response and profile changes was limited to a cephalometric analysis. Since soft tissue yields inaccurate measurements during lateral cephalograms, 3D facial scanning and electromyography could allow a more precise examination of patients’ aesthetic and functional changes. We plan to enhance the refinement of assessment modalities for both soft and hard tissues, endeavoring to substantiate vertical control’s efficacy and constraints through various methodologies, including randomized controlled trials.

The conclusions of this retrospective study are as follows.

TAD-reinforced maxillary anchorage with vertical control achieves intrusion of approximately 2 mm for the upper first molars.

TAD-reinforced maxillary anchorage with vertical control induces mandibular counterclockwise rotation of approximately 1.8° and improves patients’ hyperdivergent skeletal pattern.

When the upper incisors are not sufficiently retracted or the chin shape is not satisfying, active vertical control should be applied to help patients achieve better profiles.

Taken together, these conclusions demonstrate that TAD-assisted vertical control is essential for patients with skeletal class II and a hyperdivergent facial type. This approach constitutes a good alternative to improving occlusion and profiles via orthodontic camouflage treatment.

Data availability

The data sets used and analyzed during the current study are available from the corresponding author on reasonable request.

Abbreviations

Maxillary maximum anchorage

Temporary anchorage devices

Vertical control

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Acknowledgements

We thank LetPub ( www.letpub.com ) and Scribendi ( www.scribendi.com ) for its linguistic assistance during the preparation of this manuscript.

This project is supported by the National Program for Multidisciplinary Cooperative Treatment on Major Diseases No. PKUSSNMP-202013; China Oral Health Foundation No. A2021-021; Beijing Municipal Science & Technology Commission No. Z171100001017128; National Natural Science Foundation of China No. 81901053, No.81900984 No. 82101043 and No. 8237030822; National High Level Hospital Clinical Research Funding No. 2023-NHLHCRF-YXHZ-TJMS-05; Elite Medical Professionals Project of China-Japan Friendship Hospital No.ZRJY2023-QM05; Beijing Municipal Natural Science Foundation No. 7242282.

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Yan-Ning Guo and Sheng-Jie Cui contributed equally to this work.

Authors and Affiliations

Department of Orthodontics, National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology & Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, Peking University School and Hospital of Stomatology, No.22, Zhongguancun South Avenue, Haidian District, Beijing, 100081, China

Yan-Ning Guo, Sheng-Jie Cui, Jie-Ni Zhang, Yan-Heng Zhou & Xue-Dong Wang

Dental Medical Center, China-Japan Friendship Hospital, Beijing, 100029, China

Yan-Ning Guo

Department of Orthodontics, the School of Stomatology, The Key Laboratory of Stomatology, Hebei Medical University, Shijiazhuang, 050017, China

Fourth Division Department, National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology & Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health & NMPA Key Laboratory for Dental Materials, Peking University School and Hospital of Stomatology, Beijing, 100081, China

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Contributions

Y-N G and S-J C: Investigation, Visualization, Writing - Original draft preparation, contributed equally to this work and joint first authors. Y L: Methodology, Investigation, Data Curation, and critically revised the manuscript. Y F: Investigation, Data Curation, and critically revised the manuscript. J-N Z, Y-H Z: Supervision and critically revised the manuscript. X-D W: Conceptualization, Validation, Writing- Reviewing and Editing, Corresponding author. All authors reviewed the manuscript.

Corresponding author

Correspondence to Xue-Dong Wang .

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Ethics approval and consent to participate.

This study was approved by the Biomedical Ethics Committee of Peking University School and Hospital of Stomatology. (PKUSSIRB-201630096, retrospectively registered) All methods were carried out in accordance with relevant guidelines and regulations. Informed consent was obtained from all subjects and/or their legal guardian(s).

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Yan-Ning Guo, Sheng-Jie Cui joint first authors.

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Guo, YN., Cui, SJ., Liu, Y. et al. Quantitative evaluation of vertical control in orthodontic camouflage treatment for skeletal class II with hyperdivergent facial type. Head Face Med 20 , 31 (2024). https://doi.org/10.1186/s13005-024-00432-2

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DOI : https://doi.org/10.1186/s13005-024-00432-2

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