ORTHODONTIC RETAINER

The biologic aims to be considered when choosing a retainer,are
- maintenance of periodontal support,
- maintenance of optimal oral hygiene and
- maintenance of functional forces on all the teeth.

Commonly Used Retainers
Removable Acrylic Retainers
These include Hawley retainers, wrap around retainers and Barrer retainers and are constructed from a wire framework and acrylic baseplate. They can be modified for active tooth movement by activating the labial bow or by incorporating springs. They are routinely worn full time for three to six months, part time for one year to 18 months, followed by continued wear twice a week.

Bonded Retainers
These fixed retainers are constructed from .0195” or .0175” multistrand stainless steel archwire. An indirect technique is used to adapt the wire passively to a working model. The retainer is attached to the lingual surface of the teeth using floss or a specially constructed jig and is bonded in position using a light-cured composite resin. Care should be taken to clear the occlusion during placement in the maxillary arch. Excess bond on the lingual surfaces and at the gingival margins should be carefully removed, and the area polished giving smooth even surfaces which are easy to clean

Positioners
Positioners are elastomeric or rubber removable retainers that are either preformed or custom made. Preformed positioners are available for bicuspid extraction cases and non-extraction cases. Sizes are determined by measuring the mesiodistal dimensions of the six anterior teeth. These preformed positioners cannot compensate for individual variation in the size of the teeth, arch width, arch form or tooth size discrepancies. For these reasons, they should only be used temporarily

COMPARISON PAR INDEX AND ICON FOR ORTHODONTIC TREATMENT OUTCOME

In order to quantify malocclusion, occlusal traits are often given a numerical weighting system and combined into mathematical expressions called occlusal indices. The most important advantage of using occlusal indices is to maximize consistency between and within examiners. The use of the pre- and post-treatment scores to derive an estimate of treatment improvement is familiar. Peer Assessment Rating Index (PAR index) has been developed to provide a single summary score for all the occlusal anomalies which may be found in a malocclusion. The score provides an estimate of how far a case deviates from normal alignment and occlusion. The difference in scores between the pre- and post-treatment cases reflects the degree of improvement and, therefore, the success of treatment. The Index of Treatment Complexity, Outcome, and Need (ICON) has relatively lower predictive accuracy for the treatment outcome than for treatment need judgements. This study showed correlation between PAR index and ICON with respect to outcome. Twenty patients were identified who had undergone removable appliance treatment within the Orthodontics Laboratory Dentistry Faculty Hang Tuah University. Patients were included in the study if they fulfilled the following criteria: undergone removable appliance 2 years, and pre- and post-treatment study models available.

TEMPORO MANDIBULAR DYSFUNCTION AND ORTHODONTICS

Teeth are extracted for several reason in orthodontics. The most common reason for extraction is the relief of crowding and to create space to gain good alignment of the teeth. When premolar teeth are extracted for orthodontic treatment this leads to temporomandibular dysfunction (TMD) because of over retracting the upper incisors during space closure, forcing the condyle into a posterior position. It is this posterior position of the condyle within the fossa, which is presumed to cause an anteriorly displaced disc and therefore TMD .The previous study of 42 patients with a Class II division 1 malocclusion treated by the extraction of both upper first premolars and fixed appliances, 70 % showed a forward movements of mandibular basal bone and the changes in condylar position
Orthodontic treatment is needed for those whose occlusion is not functionally optimal to prevent the development of TMD.