Mandibular second premolars are the most commonly impacted teeth after maxillary canines and maxillary and mandibular third molars. Impacted teeth require very light amount of extrusive forces so as to erupt them into the dental arch. Many techniques and appliance designs such as sling shot mechanics1, cantilevers2, cross arch mechanics3 etc. have been proposed for traction of impacted mandibular premolars. The chief factors to be considered are:
- Use of a light, continuous force to move the impacted teeth.
- Reduction of side effects.
This article describes a wire designed for eruption of impacted mandibular premolars in accordance with the above factors.
The extraction of the lower incisors constitutes a therapeutic alternative in treating certain anomalies. It is not a standard approach to symmetrically treating most malocclusions, but in certain clinical situations the therapeutic aims must be adjusted to individual patient needs, even when this means that achieved final occlusion is not ideal. The deliberate extraction of a lower incisor in certain cases allows the orthodontist to improve occlusion and dental aesthetics. One way of preventing relapse is to extract an incisor with extreme malpositioning, which moreover limits the sometimes unnecessary movement of many teeth; correction thus becomes more circumscribed to a specific dentition zone. This article highlights the importance, indication, advantages and disadvantages of incisor extraction.
Keywords: Crowding, Mandibular incisor extraction, Bolton discrepancy
A relatively small number of orthodontic patients are affected by known genetic syndromes that affect oral structures. The greatest value in knowing that a patient has a particular syndrome is that it allows a much better prediction of future development in the individual who will not grow in the normal pattern. Sometimes recognizing a syndrome is made more difficult by incomplete expression of the genes. If a genetic syndrome is suspected, then the orthodontist should have the patient evaluated.
Objective: To evaluate mechanism of muscle response with rigid fixed functional appliance.
Material and method: An electromyographic study was performed on 20 young growing females with Class II Division 1 malocclusion. Group 1 (n=10) served as control group and group 2 (n=10) were treated with rigid fixed functional appliance. Bilateral EMG activity from anterior temporalis and masseter muscles was monitored longitudinally to determine changes in postural, swallowing, and maximal voluntary clenching during an observation period of 6 months.
Results: There was a significant decrease in EMG activity during swallowing of saliva (p< .05) and maximal clenching (p< .01) & (p< .001) in group 2, which persisted for up to 1 month, gradually returning toward pre appliance levels near the end of the experimental period.
Conclusion: A definite response of anterior temporalis and masseter muscles was observed and there was adequate neuromuscular adaptation following insertion of rigid fixed functional appliance at the end of six months. As the EMG activity in the muscles investigated in the present study is decreased significantly, our data is consistent with the concept which assigns a major role to the viscoelastic elements of muscle and increased lip strength as the source of stimulus for bone remodeling associated with the action of these appliances.
Keywords: Muscle response, Rigid fixed functional appliance, EMG activity, Masseter, Anterior temporalis.
Clinical relevance: We conducted an EMG study on patients treated with Mandibular Protraction Appliance IV (MPA IV), a rigid fixed functional appliance, as no study has been undertaken till date to evaluate mechanism of neuromuscular adaptations with it. Even though this appliance functions much like Herbst, it uses smaller tubes and rods, can be fabricated easily by the clinicians without any laboratory expense or additional inventory; is inexpensive, simple, effective and reliable corrective appliance that benefits not only growing patients but also adult malocclusions that previously required extractions, headgears, surgery or expensive accessories. It provides excellent alternative when commercially available fixed functional appliances are not available.