Myofunctional Appliances

• Myofunctional appliances are removable or fixed devices that aim to correct dental and skeletal discrepancies by promoting proper oral and facial muscle function. They are based on the principles of myofunctional therapy, which focuses on the relationship between muscle function and dental alignment.

1. Mechanism of Action:

   • These appliances work by encouraging the correct positioning of the tongue, lips, and cheeks, which can help guide the growth of the jaws and the alignment of the teeth. They can also help in retraining oral muscle habits that may contribute to malocclusion, such as thumb sucking or mouth breathing.

Types of Myofunctional Appliances

1. Functional Appliances:

   • Bionator: A removable appliance that encourages forward positioning of the mandible and helps in correcting Class II malocclusions.
   • Frankel Appliance: A removable appliance that modifies the position of the dental arches and improves facial aesthetics by influencing muscle function.
   • Activator: A functional appliance that promotes mandibular growth and corrects dental relationships by positioning the mandible forward.

2. Tongue Retainers:

   • Devices designed to maintain the tongue in a specific position, often used to correct tongue thrusting habits that can lead to malocclusion.

3. Mouthguards:

   • While primarily used for protection during sports, certain types of mouthguards can also be designed to promote proper tongue posture and prevent harmful oral habits.

4. Myobrace:

   • A specific type of myofunctional appliance that is used to correct dental alignment and improve oral function by encouraging proper tongue posture and lip closure.

Indications for Use

• Malocclusions: Myofunctional appliances are often indicated for treating Class II and Class III malocclusions, as well as other dental alignment issues.
• Oral Habits: They can help in correcting harmful oral habits such as thumb sucking, tongue thrusting, and mouth breathing.
• Facial Growth Modification: These appliances can be used to influence the growth of the jaws in growing children, promoting a more favorable dental and facial relationship.
• Improving Oral Function: They can enhance functions such as chewing, swallowing, and speech by promoting proper muscle coordination.

Advantages of Myofunctional Appliances

1. Non-Invasive: Myofunctional appliances are generally non-invasive and can be a more comfortable option for patients compared to fixed appliances.
2. Promotes Natural Growth: They can guide the natural growth of the jaws and teeth, making them particularly effective in growing children.
3. Improves Oral Function: By retraining oral muscle function, these appliances can enhance overall oral health and function.
4. Aesthetic Appeal: Many myofunctional appliances are less noticeable than traditional braces, which can be more appealing to patients.

Limitations of Myofunctional Appliances

1. Compliance Dependent: The effectiveness of myofunctional appliances relies heavily on patient compliance. Patients must wear the appliance as prescribed for optimal results.
2. Limited Scope: While effective for certain types of malocclusions, myofunctional appliances may not be suitable for all cases, particularly those requiring significant tooth movement or surgical intervention.
3. Adjustment Period: Patients may experience discomfort or difficulty adjusting to the appliance initially, which can affect compliance.

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

1. Retained Infantile Swallow:

   • The tongue does not drop back as it should after the eruption of incisors, continuing to thrust forward during swallowing.

2. Upper Respiratory Tract Infection:

   • Conditions such as mouth breathing and allergies can contribute to tongue thrusting behavior.

3. Neurological Disturbances:

   • Issues such as hyposensitivity of the palate or disruption of sensory control and coordination during swallowing can lead to tongue thrust.

4. Feeding Practices:

   • Bottle feeding is more likely to contribute to the development of tongue thrust compared to breastfeeding.

5. 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.

6. Hereditary Factors:

   • A family history of tongue thrusting or related oral habits may contribute to the development of the condition.

7. 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

1. Tongue Posture: The tongue tip is lower at rest due to the presence of an anterior open bite.
2. Malocclusion:
   • Maxilla:
     • Proclination of maxillary anterior teeth.
     • Increased overjet.
     • Maxillary constriction.
     • Generalized spacing between teeth.
   • Mandible:
     • Retroclination of mandibular teeth.

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

1. 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.

2. 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

1. 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.

2. Myofunctional Therapy:

   • Involves exercises to improve tongue posture and function, helping to retrain the muscles involved in swallowing and speech.

3. 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.

4. Speech Therapy:

   • If speech issues are present, working with a speech therapist can help address articulation problems and improve speech clarity.

5. Monitoring and Follow-Up:

   • Regular follow-up appointments to monitor progress and make necessary adjustments to the treatment plan.

Catalan's Appliance

Catalan's appliance, also known as the Catalan appliance or lower inclined bite plane, is an orthodontic device primarily used to correct anterior crossbites and manage dental arch relationships. It is particularly effective in growing children and adolescents, as it helps to guide the development of the dental arches and improve occlusion.

Indications for Use

1. Anterior Crossbite:

   • The primary indication for Catalan's appliance is to correct anterior crossbites, where the upper front teeth are positioned behind the lower front teeth when the jaws are closed.

2. Space Management:

   • It can be used to create space in the dental arch, especially when there is crowding or insufficient space for the eruption of permanent teeth.

3. Guiding Eruption:

   • The appliance helps guide the eruption of the permanent teeth into a more favorable position, promoting proper alignment.

4. Facilitating Growth:

   • It can assist in the growth of the maxilla and mandible, helping to achieve a more balanced facial profile.

Design and Features

• Components:

  • The Catalan's appliance typically consists of:
    • Acrylic Base: A custom-fitted acrylic base that covers the lower anterior teeth.
    • Inclined Plane: An inclined plane is incorporated into the appliance, which helps to reposition the anterior teeth by providing a surface for the teeth to occlude against.
    • Retention Mechanism: The appliance is retained in the mouth using clasps or other anchorage methods to ensure stability during treatment.

• Customization:

  • The appliance is custom-made for each patient based on their specific dental anatomy and treatment needs. This ensures a proper fit and effective function.

Mechanism of Action

• Correction of Crossbite:

  • The inclined plane of the Catalan's appliance exerts forces on the anterior teeth, encouraging them to move into a more favorable position. This helps to correct the crossbite by allowing the maxillary incisors to move forward relative to the mandibular incisors.

• Space Creation:

  • By repositioning the anterior teeth, the appliance can create additional space in the dental arch, facilitating the eruption of permanent teeth and improving overall alignment.

• Guiding Eruption:

  • The appliance helps guide the eruption of the permanent teeth by maintaining proper arch form and preventing unwanted movements of the teeth.

Anterior Crossbite

Anterior crossbite is a dental condition where one or more of the upper front teeth (maxillary incisors) are positioned behind the lower front teeth (mandibular incisors) when the jaws are closed. This misalignment can lead to functional issues, aesthetic concerns, and potential wear on the teeth. Correcting anterior crossbite is essential for achieving proper occlusion and improving overall dental health.

Methods to Correct Anterior Crossbite

1. Acrylic Incline Plane:

   • Description: An acrylic incline plane is a removable appliance that can be used to guide the movement of the teeth. It is designed to create a ramp-like surface that encourages the maxillary incisors to move forward.
   • Mechanism: The incline plane helps to reposition the maxillary teeth by providing a surface that directs the teeth into a more favorable position during function.

2. Reverse Stainless Steel Crown:

   • Description: A reverse stainless steel crown can be used in cases where the anterior teeth are significantly misaligned. This crown is designed to provide a stable and durable solution for correcting the crossbite.
   • Mechanism: The crown can be adjusted to help reposition the maxillary teeth, allowing them to move into a more normal relationship with the mandibular teeth.

3. Hawley Retainer with Recurve Springs:

   • Description: A Hawley retainer is a removable orthodontic appliance that can be modified with recurve springs to correct anterior crossbite.
   • Mechanism: The recurve springs apply gentle pressure to the maxillary incisors, tipping them forward into a more favorable position relative to the mandibular teeth. This appliance is comfortable, easily retained, and predictable in its effects.

4. Fixed Labial-Lingual Appliance:

   • Description: A fixed labial-lingual appliance is a type of orthodontic device that is bonded to the teeth and can be used to correct crossbites.
   • Mechanism: This appliance works by applying continuous forces to the maxillary teeth, tipping them forward and correcting the crossbite. It may include a vertical removable arch for ease of adjustment and recurve springs to facilitate movement.

5. Vertical Removable Arch:

   • Description: This appliance can be used in conjunction with other devices to provide additional support and adjustment capabilities.
   • Mechanism: The vertical removable arch allows for easy modifications and adjustments, helping to jump the crossbite by repositioning the maxillary teeth.

Forces Required for Tooth Movements

1. Tipping:

   • Force Required: 50-75 grams
   • Description: Tipping involves the movement of a tooth around its center of resistance, resulting in a change in the angulation of the tooth.

2. Bodily Movement:

   • Force Required: 100-150 grams
   • Description: Bodily movement refers to the translation of a tooth in its entirety, moving it in a straight line without tipping.

3. Intrusion:

   • Force Required: 15-25 grams
   • Description: Intrusion is the movement of a tooth into the alveolar bone, effectively reducing its height in the dental arch.

4. Extrusion:

   • Force Required: 50-75 grams
   • Description: Extrusion involves the movement of a tooth out of the alveolar bone, increasing its height in the dental arch.

5. Torquing:

   • Force Required: 50-75 grams
   • Description: Torquing refers to the rotational movement of a tooth around its long axis, affecting the angulation of the tooth in the buccolingual direction.

6. Uprighting:

   • Force Required: 75-125 grams
   • Description: Uprighting is the movement of a tilted tooth back to its proper vertical position.

7. Rotation:

   • Force Required: 50-75 grams
   • Description: Rotation involves the movement of a tooth around its long axis, changing its orientation within the dental arch.

8. Headgear:

   • Force Required: 350-450 grams on each side
   • Duration: Minimum of 12-14 hours per day
   • Description: Headgear is used to control the growth of the maxilla and to correct dental relationships.

9. Face Mask:

   • Force Required: 1 pound (450 grams) per side
   • Duration: 12-14 hours per day
   • Description: A face mask is used to encourage forward growth of the maxilla in cases of Class III malocclusion.

10. Chin Cup:

    • Initial Force Required: 150-300 grams per side
    • Subsequent Force Required: 450-700 grams per side (after two months)
    • Duration: 12-14 hours per day
    • Description: A chin cup is used to control the growth of the mandible and improve facial aesthetics.

Types of Removable Orthodontic Appliances

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.