Treatment Effect of Combined Surgical Maxillary Expansion and Mandibular Setback in Skeletal Class III.

The purpose of this case report is to describe and discuss a combined surgical and orthodontic technique for the management of transverse maxillary deficiency and mandibular prognathism in the treatment of skeletal Class III malocclusion in a mature patient. Skeletal Class III malocclusion can present with maxillary deficiency or retrognathism, mandibular excess or prognathism, or a combination. The maxillary arch is narrow and often requires expansion. A 25-year-old patient presented with a constricted maxilla, a skeletal Class III malocclusion with a large mandible, Angle's Class III malocclusion, retroclined lower incisors, proclined upper incisors, crowding of maxillary and mandibular teeth, and bilateral posterior crossbite. The case report shows that an adult patient with Class III malocclusion (constricted maxilla and large mandible) can be treated with rapid maxillary expansion accompanied by bilateral maxillary osteotomies, followed by a reduction bilateral sagittal split osteotomy (BSSO). As the patient was 25 years old with a bilateral crossbite, a surgically assisted rapid maxillary expansion procedure was performed. As the diastema space was available at the end of expansion, it proved to be beneficial for the presurgical decompensation of Class III, thus creating a negative overjet, followed by which a BSSO setback was done.

Biomechanics of torque from twisted rectangular archwires. A finite element investigation.

OBJECTIVE: To evaluate the magnitudes of initial and subsequent sequential deactivational third-order moments generated in rectangular twisted archwires (either when the archwires are actually twisted before insertion in the standard edgewise bracket slots or when they are indirectly twisted in the preadjusted slots of the modern edgewise brackets) in order to judge their biologic acceptability. MATERIALS AND METHODS: A finite element study was carried out with the MSC Patran/Nastran interface. Three-dimensional models were constructed with 170 nodes of upper 0.017- x 0.025-inch and 0.019- x 0.025-inch archwire segments extending bilaterally from the maxillary central incisors to the first premolars. Required twists were applied at the appropriate locations to derive the applied and reactionary moments both initially and during the time needed for complete deactivation. RESULTS: The results indicated that a round-tripping possibility does exist in certain clinical procedures. Furthermore, the moments produced could be quite high, thereby enhancing the possibility of root resorption. CONCLUSIONS: Twists in rectangular archwires may be used only when reciprocal torque is needed on adjacent teeth. In other situations, alternative torquing methods should be considered.