Ruweda Dawids theory 2

Discuss why it is inappropriate to use any form of cervical traction or pull that is directed horizontally when applying extra oral force to a functional appliance?

Cervical pull is achieved by the use of traction device which is one of the components of a headgear appliance. It fits around the pt’s neck. The desirable force required should be exerted parallel to the occlusal plane. It is used to stabilize or distalize the first maxillary molars.

Ruweda Dawids, Theory 1

What orthopedic changes can be achieved by the long term action of a functional appliance?
The use of functional appliances offers a number of possibilities such as guiding skeletal growth and modifies the patient’s neuro-muscular behaviour. There are several functional appliances available and each of them has different functions. The different functional appliances and their functions:
• A Clark twin block appliance incorporates the use of upper and lower bite blocks to position the mandible forward for skeletal Class II correction.
• Headgear is an orthodontic appliance for the correction of Class II correction, typically used in growing patients to correct overbites by holding back the growth of the upper jaw, allowing the lower jaw to catch up. The headgear can also be used to make more space for teeth to come in. Headgear needs to be worn approximately 12 to 22 hours a day to be truly effective in correcting the overbite, and treatment is usually anywhere from 6 to 18 months in duration, depending on the severity of the overbite and how much a patient is growing.
• Orthodontic facemask and reverse-pull headgear The appliance is used in growing patients to correct under bites known as a Class III orthodontic problem by pulling forward and assisting the growth of the upper jaw, allowing the upper jaw to catch up.
• Herbst Appliance corrects overbites by holding the lower jaw in a protrusive position. This appliance is most commonly used in non-compliant patients. The Herbst appliance is very effective in correcting large overbites due to small lower jaws in patients that are growing.
• Fixed twin block removable appliance- high comfort level allows you to wear it 24 hours a day. This appliance actually is made up of two separate appliances that work together as one. The upper plate includes an optional expansion screw to widen your upper arch, if needed, as well as pads to cover your molars. The lower plate includes pads to cover your lower bicuspids. These two appliances interlock at an angle, and they move your lower jaw forward and lock it into the ideal position when you bite together. This new position, while temporary, will eventually become the permanent corrected position.

Sindile Gcelu, Material Science I

When applying extra oral force to a functional appliance it is important to remember not to use any form of cervical traction or pull that is directed horizontally.
Explain why and also indicate the most desirable direction of force to be used with a functional appliance
Muir & Reed (1979) states that most multiband appliance systems make extensive use of extra oral forces. By comparison such forces are much less used with removable appliances. There is no good clinical reason why this should be so. Extra oral forces can readily be adapted for use in removable appliance orthodontics and can extend considerably the range of treatment which can be undertaken.

It is possible that heavy extra oral force applied for a substantial proportion of each day to a patient who is growing rapidly may have an orthopaedic effect. In addition to distal movement of teeth through bone there could be a restraint on maxillary growth. Headgear can be applied either directly to a removable appliance or indirectly to molar bands over which the appliance is clipped. Therefore, it is necessary to avoid patterns of headgear that delivers cervical traction (neck strap). It is recommended to use full headgear when applying force directly to a removable appliance.

Ref: Muir, J.D., Reed, R.T. 1979. Tooth Movement with Removable Appliances. USA: Pitman Medical. Pg 82.

Sindile Gcelu Theory 2

Without referring to any of the study material that deals with the historical and functional development of the Functional Appliance, give your own evaluation or opinion as to the effectiveness of these appliancesAccording to Graber & Neumann (1997) indicates that, the maximum power of the muscle activity is not as important as the orderly coordination of the manifold functions. Malocclusion thus must be regarded as a disturbance of that coordination, there may be a cause of the in coordinate activity. Of no minor importance may be the psychological component, producing Para functional influences by which the action of the finger, tongue, lips, cheeks, etc. will produce deformation. 

Sindile Gcelu, Theory I

Balters, who developed the Bionator appliance, claimed that malocclusion was caused by a lack of correct co-ordination of the various muscle functions. Explain his claims that a Class II malocclusion treated with a Bionator appliance will normalise functions and lead to harmony of anatomic relations.
According to Balters’ philosophy, Class II malocclusions are a consequence of a backward position of the tongue, disturbing the cervical region. The respiratory function is impeded in the region of the larynx and there is thus a faulty deglutition. Alongside, there is mouth breathing.
Effectiveness of Bionator appliance:
• To accomplish lip closure and bring the back of the tongue into contact with the soft palate.
• To enlarge the oral space and to train its function.
• To bring the incisors into an edge-to-edge incision or relationship.
• To achieve an elongation of the mandible, which in turn will enlarge the oral space and make the improved tongue position possible?
• An improved relationship of the jaws, tongue, and dentition, as well as the surrounding soft tissue will result.

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Cheryl Wolfe Theory 2

The objectives of Functional Therapy (treatment):

In order for normal development of the dental arches in the correct relationship to occur, favourable equilibrium of muscle forces between the tongue, lip and cheeks are essential. Malocclusion is therefore a result of persistant deviation from normal function. The purpose of functional therapy is therefore to change the functional environment of the dentition to promote normal function. The purpose of a functional appliance is to control the forces applied to the dentition by the surrounding soft tissues as well as the muscles that control the position and movement of the mandible. A new functional behaviour pattern is therefore established in order to support a new position of equilibrium by eliminating unfavourable environmental factors in a developing malocclusion. Functional thereapy also aims to unlock a malocclusion and stimulate growth by applying favourable forces that enhance skeletal development.

Clark, W.J. 1995. Twin Block Functional Therapy: Applications in Dentofacial Orthopaedics. London: Mosby-Wolfe. p31-32