NEET MDS Lessons
Orthodontics
Types of Removable Orthodontic Appliances
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Functional Appliances:
- Purpose: Designed to modify the growth of the jaw and improve the relationship between the upper and lower teeth.
- Examples:
- Bionator: Encourages forward positioning of the mandible.
- Frankel Appliance: Used to modify the position of the dental arches and improve facial aesthetics.
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Retainers:
- Purpose: Used to maintain the position of teeth after orthodontic treatment.
- Types:
- Hawley Retainer: A custom-made acrylic plate with a wire framework that holds the teeth in position.
- Essix Retainer: A clear, plastic retainer that fits over the teeth, providing a more aesthetic option.
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Space Maintainers:
- Purpose: Used to hold space for permanent teeth when primary teeth are lost prematurely.
- Types:
- Band and Loop: A metal band placed on an adjacent tooth with a loop extending into the space.
- Distal Shoe: A space maintainer used in the lower arch to maintain space for the first molar.
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Aligners:
- Purpose: Clear plastic trays that gradually move teeth into the desired position.
- Examples:
- Invisalign: A popular brand of clear aligners that uses a series of custom-made trays to achieve tooth movement.
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Expansion Appliances:
- Purpose: Used to widen the dental arch, particularly in cases of crossbite or narrow arches.
- Examples:
- Rapid Palatal Expander (RPE): A device that applies pressure to the upper molars to widen the maxilla.
Components of Removable Orthodontic Appliances
- Baseplate: The foundation of the appliance, usually made of acrylic, which holds the other components in place.
- Active Components: Springs, screws, or other mechanisms that exert forces on the teeth to achieve movement.
- Retention Components: Clasps or other features that help keep the appliance securely in place during use.
- Adjustable Parts: Some appliances may have adjustable components to fine-tune the force applied to the teeth.
Indications for Use
- Correction of Malocclusions: Removable appliances can be used to address various types of malocclusions, including crowding, spacing, and crossbites.
- Space Maintenance: To hold space for permanent teeth when primary teeth are lost prematurely.
- Tooth Movement: To move teeth into desired positions, particularly in growing patients.
- Retention: To maintain the position of teeth after orthodontic treatment.
- Jaw Relationship Modification: To influence the growth of the jaw and improve the relationship between the dental arches.
Advantages of Removable Orthodontic Appliances
- Patient Compliance: Patients can remove the appliance for eating, brushing, and social situations, which can improve compliance.
- Hygiene: Easier to clean compared to fixed appliances, reducing the risk of plaque accumulation and dental caries.
- Flexibility: Can be adjusted or modified as treatment progresses.
- Less Discomfort: Generally, removable appliances are less uncomfortable than fixed appliances, especially during initial use.
- Aesthetic Options: Clear aligners and other aesthetic appliances can be more visually appealing to patients.
Disadvantages of Removable Orthodontic Appliances
- Compliance Dependent: The effectiveness of removable appliances relies heavily on patient compliance; if not worn as prescribed, treatment may be delayed or ineffective.
- Limited Force Application: They may not be suitable for complex tooth movements or significant skeletal changes.
- Adjustment Period: Some patients may experience discomfort or difficulty speaking initially.
Camouflage in orthodontics refers to the strategic use of orthodontic treatment to mask or disguise underlying skeletal discrepancies, particularly in cases where surgical intervention may not be feasible or desired by the patient. This approach aims to improve dental alignment and occlusion while minimizing the appearance of skeletal issues, such as Class II or Class III malocclusions.
Key Concepts of Camouflage in Orthodontics
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Objective:
- The primary goal of camouflage is to create a more aesthetically pleasing smile and functional occlusion without addressing the underlying skeletal relationship directly. This is particularly useful for patients who may not want to undergo orthognathic surgery.
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Indications:
- Camouflage is often indicated for:
- Class II Malocclusion: Where the lower jaw is positioned further back than the upper jaw.
- Class III Malocclusion: Where the lower jaw is positioned further forward than the upper jaw.
- Mild to Moderate Skeletal Discrepancies: Cases where the skeletal relationship is not severe enough to warrant surgical correction.
- Camouflage is often indicated for:
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Mechanisms:
- Tooth Movement: Camouflage typically involves
moving the teeth into positions that improve the occlusion and facial
aesthetics. This may include:
- Proclination of Upper Incisors: In Class II cases, the upper incisors may be tilted forward to improve the appearance of the bite.
- Retroclination of Lower Incisors: In Class III cases, the lower incisors may be tilted backward to help achieve a better occlusal relationship.
- Use of Elastics: Orthodontic elastics can be employed to help correct the bite and improve the overall alignment of the teeth.
- Tooth Movement: Camouflage typically involves
moving the teeth into positions that improve the occlusion and facial
aesthetics. This may include:
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Treatment Planning:
- A thorough assessment of the patient's dental and skeletal
relationships is essential. This includes:
- Cephalometric Analysis: To evaluate the skeletal relationships and determine the extent of camouflage needed.
- Clinical Examination: To assess the dental alignment, occlusion, and any functional issues.
- Patient Preferences: Understanding the patient's goals and preferences regarding treatment options.
- A thorough assessment of the patient's dental and skeletal
relationships is essential. This includes:
Advantages of Camouflage
- Non-Surgical Option: Camouflage provides a way to improve dental alignment and aesthetics without the need for surgical intervention, making it appealing to many patients.
- Shorter Treatment Time: In some cases, camouflage can lead to shorter treatment times compared to surgical options.
- Improved Aesthetics: By enhancing the appearance of the smile and occlusion, camouflage can significantly boost a patient's confidence and satisfaction.
Limitations of Camouflage
- Not a Permanent Solution: While camouflage can improve aesthetics and function, it does not address the underlying skeletal discrepancies, which may lead to long-term issues.
- Potential for Relapse: Without proper retention, there is a risk that the teeth may shift back to their original positions after treatment.
- Functional Complications: In some cases, camouflage may not fully resolve functional issues related to the bite, leading to potential discomfort or wear on the teeth.
Tongue Thrust
Tongue thrust is characterized by the forward movement of the tongue tip between the teeth to meet the lower lip during swallowing and speech, resulting in an interdental position of the tongue (Tulley, 1969). This habit can lead to various dental and orthodontic issues, particularly malocclusions such as anterior open bite.
Etiology of Tongue Thrust
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Retained Infantile Swallow:
- The tongue does not drop back as it should after the eruption of incisors, continuing to thrust forward during swallowing.
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Upper Respiratory Tract Infection:
- Conditions such as mouth breathing and allergies can contribute to tongue thrusting behavior.
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Neurological Disturbances:
- Issues such as hyposensitivity of the palate or disruption of sensory control and coordination during swallowing can lead to tongue thrust.
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Feeding Practices:
- Bottle feeding is more likely to contribute to the development of tongue thrust compared to breastfeeding.
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Induced by Other Oral Habits:
- Habits like thumb sucking or finger sucking can create malocclusions (e.g., anterior open bite), leading to the tongue protruding between the anterior teeth during swallowing.
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Hereditary Factors:
- A family history of tongue thrusting or related oral habits may contribute to the development of the condition.
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Tongue Size:
- Conditions such as macroglossia (enlarged tongue) can predispose individuals to tongue thrusting.
Clinical Features
Extraoral
- Lip Posture: Increased lip separation both at rest and during function.
- Mandibular Movement: The path of mandibular movement is upward and backward, with the tongue moving forward.
- Speech: Articulation problems, particularly with sounds such as /s/, /n/, /t/, /d/, /l/, /th/, /z/, and /v/.
- Facial Form: Increased anterior facial height may be observed.
Intraoral
- Tongue Posture: The tongue tip is lower at rest due to the presence of an anterior open bite.
- Malocclusion:
- Maxilla:
- Proclination of maxillary anterior teeth.
- Increased overjet.
- Maxillary constriction.
- Generalized spacing between teeth.
- Mandible:
- Retroclination of mandibular teeth.
- Maxilla:
Diagnosis
History
- Family History: Determine the swallow patterns of siblings and parents to check for hereditary factors.
- Medical History: Gather information regarding upper respiratory infections and sucking habits.
- Patient Motivation: Assess the patient’s overall abilities, interests, and motivation for treatment.
Examination
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Swallowing Assessment:
- Normal Swallowing:
- Lips touch tightly.
- Mandible rises as teeth come together.
- Facial muscles show no marked contraction.
- Abnormal Swallowing:
- Teeth remain apart.
- Lips do not touch.
- Facial muscles show marked contraction.
- Normal Swallowing:
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Inhibition Test:
- Lightly hold the lower lip with a thumb and finger while the patient is asked to swallow water.
- Normal Swallowing: The patient can swallow normally.
- Abnormal Swallowing: The swallow is inhibited, requiring strong mentalis and lip contraction for mandibular stabilization, leading to water spilling from the mouth.
Management
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Behavioral Therapy:
- Awareness Training: Educate the patient about the habit and its effects on oral health.
- Positive Reinforcement: Encourage the patient to practice proper swallowing techniques and reward progress.
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Myofunctional Therapy:
- Involves exercises to improve tongue posture and function, helping to retrain the muscles involved in swallowing and speech.
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Orthodontic Treatment:
- If malocclusion is present, orthodontic intervention may be necessary to correct the dental alignment and occlusion.
- Appliances such as a palatal crib or tongue thrusting appliances can be used to discourage the habit.
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Speech Therapy:
- If speech issues are present, working with a speech therapist can help address articulation problems and improve speech clarity.
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Monitoring and Follow-Up:
- Regular follow-up appointments to monitor progress and make necessary adjustments to the treatment plan.
BONES OF THE SKULL
A) Bones of the cranial base:
A) Fontal (1)
B) Ethmoid (1)
C) Sphenoid (1)
D) Occipital (1)
B) Bones of the cranial vault:
1. Parietal (2)
2. Temporal (2)
C) Bones of the face:
Maxilla (2)
Mandible (1)
Nasal bone (2)
Lacrimal bone (2)
Zygomatic bone (2)
Palatine bone(2)
Infra nasal concha (2)
FUSION BETWEEN BONES
1. Syndesmosis: Membranous or ligamentus eg. Sutural point.
2. Synostosis: Bony union eg. symphysis menti.
3. Synchondrosis: Cartilaginous eg. sphenoccipital, spheno-ethmoidal.
GROWTH OF THE SKULL:
A) Cranium: 1. Base 2. Vault
B) Face: 1. Upper face 2.Lower face
CRANIAL BASE:
Cranial base grows at different cartilaginous suture. The cranial base may be divided into 3 areas.
1. The posterior part which extends from the occiput to the salatercica. The most important growth site spheno-occipital synchondrosis is situated here. It is active throughout the growing period and does not close until early adult life.
2. The middle portion extends from sella to foramen cecum and the sutural growth spheno-ethmoidal synchondrosis is situated here. The exact time of closing is not known but probably at the age of 7 years.
3. The anterior part is from foramen cecum and grows by surface deposition of bone in the frontal region and simultaneous development of frontal sinus.
CRANIAL VAULT:
The cranial vault grows as the brain grows. It is accelerated at infant. The growth is complete by 90% by the end of 5th year. At birth the sutures are wide sufficiently and become approximated during the 1st 2 years of life.
The development and extension of frontal sinus takes place particularly at the age of puberty and there is deposition of bone on the surfaces of cranial bone.
Orthodontic Force Duration
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Continuous Forces:
- Definition: Continuous forces are applied consistently over time without interruption.
- Application: Many extraoral appliances, such as headgear, are designed to provide continuous force to the teeth and jaws. This type of force is essential for effective tooth movement and skeletal changes.
- Example: A headgear may be worn for 12-14 hours a day to achieve the desired effects on the maxilla or mandible.
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Intermittent Forces:
- Definition: Intermittent forces are applied in a pulsed or periodic manner, with breaks in between.
- Application: Some extraoral appliances may use intermittent forces, but this is less common. Intermittent forces can be effective in certain situations, but continuous forces are generally preferred for consistent tooth movement.
- Example: A patient may be instructed to wear an appliance for a few hours each day, but this is less typical for extraoral devices.
Force Levels
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Light Forces:
- Definition: Light forces are typically in the range of 50-100 grams and are used to achieve gentle tooth movement.
- Application: Light forces are ideal for orthodontic treatment as they minimize discomfort and reduce the risk of damaging the periodontal tissues.
- Example: Some extraoral appliances may be designed to apply light forces to encourage gradual movement of the teeth or to modify jaw relationships.
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Moderate Forces:
- Definition: Moderate forces range from 100-200 grams and can be used for more significant tooth movement or skeletal changes.
- Application: These forces can be effective in achieving desired movements but may require careful monitoring to avoid discomfort or adverse effects.
- Example: Headgear that applies moderate forces to the maxilla to correct Class II malocclusions.
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Heavy Forces:
- Definition: Heavy forces exceed 200 grams and are typically used for rapid tooth movement or significant skeletal changes.
- Application: While heavy forces can lead to faster results, they also carry a higher risk of complications, such as root resorption or damage to the periodontal ligament.
- Example: Some extraoral appliances may apply heavy forces for short periods, but this is generally not recommended for prolonged use.
Growth is the increase in size It may also be defined as the normal change in the amount of living substance. eg. Growth is the quantitative aspect and measures in units of increase per unit of time.
Development
It is the progress towards maturity (Todd). Development may be defined as natural sequential series of events between fertilization of ovum and adult stage.
Maturation
It is a period of stabilization brought by growth and development.
CEPHALOCAUDAL GRADIENT OF GROWTH
This simply means that there is an axis of increased growth extending from the head towards feet. At about 3rd month of intrauterine life the head takes up about 50% of total body length. At this stage cranium is larger relative to face. In contrast the limbs are underdeveloped.
By the time of birth limbs and trunk have grown faster than head and the entire proportion of the body to the head has increased. These processes of growth continue till adult.
SCAMMON’S CURVE
In normal growth pattern all the tissue system of the body do not growth at the same rate. Scammon’s curve for growth shows 4 major tissue system of the body;
• Neural
• Lymphoid
• General: Bone, viscera, muscle.
• Genital
The graph indicates the growth of the neural tissue is complete by 6-7 year of age. General body tissue show an “S” shaped curve with showing of rate during childhood and acceleration at puberty. Lymphoid tissues proliferate to its maximum in late childhood and undergo involution. At the same time growth of the genital tissue accelerate rapidly.
Frankel appliance is a functional orthodontic device designed to guide facial growth and correct malocclusions. There are four main types: Frankel I (for Class I and Class II Division 1 malocclusions), Frankel II (for Class II Division 2), Frankel III (for Class III malocclusions), and Frankel IV (for specific cases requiring unique adjustments). Each type addresses different dental and skeletal relationships.
The Frankel appliance is a removable orthodontic device that plays a crucial role in the treatment of various malocclusions. It is designed to influence the growth of the jaw and dental arches by modifying muscle function and promoting proper alignment of teeth.
Types of Frankel Appliances
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Frankel I:
- Indications: Primarily used for Class I and Class II Division 1 malocclusions.
- Function: Helps in correcting overjet and improving dental alignment.
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Frankel II:
- Indications: Specifically designed for Class II Division 2 malocclusions.
- Function: Aims to reposition the maxilla and improve the relationship between the upper and lower teeth.
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Frankel III:
- Indications: Used for Class III malocclusions.
- Function: Encourages forward positioning of the maxilla and helps in correcting the skeletal relationship.
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Frankel IV:
- Indications: Suitable for open bites and bimaxillary protrusions.
- Function: Focuses on creating space and improving the occlusion by addressing specific dental and skeletal issues.
Key Features of Frankel Appliances
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Myofunctional Design: The appliance is designed to utilize the forces generated by muscle function to guide the growth of the dental arches.
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Removable: Patients can take the appliance out for cleaning and during meals, which enhances comfort and hygiene.
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Custom Fit: Each appliance is tailored to the individual patient's dental anatomy, ensuring effective treatment.
Treatment Goals
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Facial Balance: The primary goal of using a Frankel appliance is to achieve facial harmony and balance by correcting malocclusions.
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Functional Improvement: It promotes the establishment of normal muscle function, which is essential for long-term dental health.
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Arch Development: The appliance aids in the development of the dental arches, providing adequate space for the eruption of permanent teeth.