List of orthodontic functional appliances

**List of Orthodontic Functional Appliances**

**Definition**
Orthodontic functional appliances are devices used in orthodontics to modify the growth and position of the jaws and teeth by harnessing the functional forces generated by muscles during activities such as chewing and swallowing. These appliances are primarily employed in growing patients to correct skeletal discrepancies and improve occlusion by guiding jaw development and dental alignment.

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## Introduction

Functional appliances represent a significant category of orthodontic devices designed to influence the growth and function of the craniofacial complex. Unlike fixed appliances that primarily move teeth, functional appliances aim to modify the underlying skeletal structures by altering muscle activity and jaw posture. They are commonly used in the treatment of Class II and Class III malocclusions, where discrepancies between the maxilla and mandible exist.

This article provides a comprehensive list and description of the various types of orthodontic functional appliances, categorized by their mode of action, design, and clinical application. It also discusses their indications, mechanisms, and advantages.

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## Overview of Functional Appliances

Functional appliances can be broadly classified into removable and fixed types. Removable functional appliances are typically worn by the patient and can be taken out for eating and oral hygiene, whereas fixed functional appliances are cemented or bonded to the teeth and remain in place throughout treatment.

### Classification

– **Removable Functional Appliances**
These appliances rely on patient compliance and are often used in early or mixed dentition stages. They are designed to posture the mandible forward or backward, stimulate mandibular growth, or restrict maxillary development.

– **Fixed Functional Appliances**
Fixed appliances are attached to the dentition and apply continuous forces to modify jaw relationships. They are less dependent on patient compliance and are often used in later stages of growth or in conjunction with fixed orthodontic appliances.

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## List of Orthodontic Functional Appliances

### Removable Functional Appliances

#### 1. Activator Appliance
One of the earliest and most widely used functional appliances, the activator was developed by Viggo Andresen in the early 20th century. It postures the mandible forward to stimulate mandibular growth and correct Class II malocclusions. The appliance consists of acrylic plates covering the palate and teeth, with wire components to guide jaw positioning.

#### 2. Bionator
A modification of the activator, the bionator is a smaller, less bulky appliance that encourages mandibular advancement and improves tongue posture. It is often preferred for patient comfort and ease of speech.

#### 3. Twin Block Appliance
Developed by William J. Clark, the twin block consists of two separate removable plates—one for the maxilla and one for the mandible—with interlocking bite blocks that posture the mandible forward. It is highly effective in correcting Class II malocclusions and is popular due to its comfort and efficiency.

#### 4. Frankel Functional Regulator
The Frankel appliance uses buccal shields and lip pads to modify muscle function and encourage favorable jaw growth. It is unique in that it does not cover the teeth but instead alters the soft tissue environment to influence skeletal development.

#### 5. Monoblock Appliance
A single-piece appliance that postures the mandible forward, the monoblock is a simpler design but less commonly used due to difficulties in speech and comfort.

#### 6. Andresen Functional Appliance
Similar to the activator, this appliance postures the mandible forward and is custom-made to fit the patient’s dental arches.

#### 7. Schwarz Appliance
Primarily used for arch development, the Schwarz appliance can be modified to function as a functional appliance by incorporating components that influence jaw posture.

#### 8. Hickham Appliance
A less common functional appliance designed to correct Class II malocclusions by mandibular advancement.

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### Fixed Functional Appliances

#### 1. Herbst Appliance
The Herbst appliance is a fixed, bilateral telescoping device that postures the mandible forward continuously. It is cemented to the molars and premolars and is effective in correcting Class II malocclusions without relying on patient compliance.

#### 2. Forsus Fatigue Resistant Device
A spring-loaded fixed appliance that applies continuous force to advance the mandible, the Forsus device is often used in conjunction with fixed braces to correct Class II malocclusions.

#### 3. MARA (Mandibular Anterior Repositioning Appliance)
The MARA is a fixed appliance that postures the mandible forward using inter-arch components. It is less bulky than the Herbst and allows for some mandibular movement.

#### 4. Jasper Jumper
A fixed, spring-loaded appliance that advances the mandible, the Jasper Jumper is used to correct Class II malocclusions and is attached to the upper and lower archwires.

#### 5. Lip Bumper
Although primarily used for arch development, the lip bumper can functionally influence mandibular growth by altering lip and cheek muscle forces.

#### 6. Sabbagh Universal Spring 2 (SUS2)
A fixed functional appliance designed to posture the mandible forward with a spring mechanism, used in conjunction with fixed orthodontic appliances.

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## Mechanism of Action

Functional appliances work by altering the position of the mandible relative to the maxilla, thereby stimulating or redirecting growth at the condylar cartilage and remodeling the glenoid fossa. They also influence muscle activity, which can lead to changes in the dental arches and occlusion.

The forward positioning of the mandible stretches the muscles and soft tissues, which may promote adaptive growth responses. Additionally, functional appliances can restrict maxillary growth in some cases, contributing to improved jaw relationships.

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## Indications

Functional appliances are primarily indicated for:

– Correction of Class II malocclusions due to mandibular deficiency
– Management of mild to moderate skeletal discrepancies in growing patients
– Improvement of overjet and overbite
– Enhancement of facial profile by promoting mandibular growth
– Correction of functional shifts and habits affecting jaw development

They are most effective during periods of active growth, typically in children and adolescents.

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## Advantages and Limitations

### Advantages

– Non-invasive approach to skeletal correction
– Can reduce or eliminate the need for surgical intervention
– Improve facial aesthetics and function
– Removable appliances allow for better oral hygiene
– Fixed appliances reduce dependence on patient compliance

### Limitations

– Effectiveness depends on patient growth and compliance (for removable appliances)
– May cause discomfort or speech difficulties initially
– Limited skeletal changes in non-growing patients
– Potential for dental compensations rather than true skeletal correction
– Fixed appliances may complicate oral hygiene

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## Conclusion

Orthodontic functional appliances play a vital role in the management of skeletal malocclusions during growth. The choice of appliance depends on the specific clinical situation, patient compliance, and treatment goals. Both removable and fixed functional appliances offer unique advantages and challenges, and their appropriate use can significantly improve occlusal relationships and facial aesthetics.

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**Meta Description:**
This article provides a comprehensive list and overview of orthodontic functional appliances, detailing their types, mechanisms, indications, and clinical applications in correcting jaw discrepancies.