Corticotomy-/osteotomy-assisted tooth movement microCTs differ.

Corticotomy-assisted and osteotomy-assisted tooth movement involves surgical incisions through the alveolar bone. To ascertain whether teeth move by distraction osteogenesis or by regional accelerated phenomenon (RAP), we randomly assigned 30 Sprague-Dawley rats to one of 5 experimental groups: corticotomy alone, corticotomy-assisted tooth movement, osteotomy alone, osteotomy-assisted tooth movement, or tooth movement alone. Each animal was imaged by microtomography immediately after surgery, after 21 days, and after 2 months. After 21 days, regional accelerated phenomenon was observed in the alveolar bone of the corticotomy-treated animals and distraction osteogenesis in the osteotomy-assisted tooth movement animals. Pixel count data were analyzed by nested ANOVA for 5 experimental groups, split-mouth controls, 3 levels along the root, and 5 sites per level. The most demineralized sites after 21 days differed for each of the experimental groups. Our study indicates that osteotomies and corticotomies induce different alveolar bone reactions, which can be exploited for tooth movement.

Aggressive osteoblastoma of the mandible.

We report a case of aggressive osteoblastoma of the mandible, an extremely rare primary bone tumor of the maxillofacial skeleton. Although osteoblastomas are benign tumors requiring only curettage for cure, there is a small subset of tumors that exhibit locally aggressive behavior and have atypical histopathologic features. Differentiation from low-grade osteosarcoma is often difficult. There is some disagreement as to the proper classification of these tumors. The correct diagnosis must be based on clinical, radiographic and pathologic features. Surgical resection and reconstruction is the recommended treatment for these invasive lesions.

Orthodontic spring guidance of bilateral mandibular distraction in rabbits.

Although distraction osteogenesis can lengthen congenitally small mandibles, the distraction procedure can be difficult to control. To study the efficacy and safety of orthodontic spring guidance on bilateral mandibular distraction, an 8-mm anterior open bite was experimentally produced and corrected during bilateral mandibular distraction in rabbits. Orthodontic springs were attached to the anterior maxilla and mandible to redirect an ongoing distraction procedure. Sixteen rabbits underwent mandibular distraction: 6 rabbits received heavy springs (8 oz), 6 rabbits received light force springs (2 oz), and 4 rabbits served as control animals with anterior open bites without spring guidance. Nickel-titanium springs were applied during the last week of osseous distraction and the first week of consolidation. Distractors were left in place throughout a 2-month consolidation period. None of the animals developed fibrous union as a result of spring guidance. The 8-mm open bite did not close in the control group or in the light spring group after 2 weeks of spring wear or during the consolidation period. Heavy springs completely closed the experimental open bites within 2 weeks (P <.01, analysis of variance). Bite corrections did not change during the consolidation period. This study indicated that the addition of an orthodontic spring to a mandibular distraction procedure did not impair bone healing. With the distraction device in place, heavy spring forces redirected an ongoing mandibular distraction procedure and corrected an open bite, distraction side effect. Direct measurements, radiographic measurements, and tissue histologic factors described changes in segment position and shape of the distraction site.

Bending of the distraction site during mandibular distraction osteogenesis in the rabbit: a model for studying segment control and side effects.

PURPOSE: The purpose of this investigation was to develop an animal model for studying and correcting mandibular distraction side effects. MATERIALS AND METHODS: Twenty-nine rabbits underwent bilateral mandibular distraction. Bending of the mandible was accomplished by offsetting a linear distraction by 35 degrees from the occlusal plane (4 screws per distractor), rotating the anterior segment inferiorly (2 screws per distractor), and removing a 3- or 6-mm wedge of the distraction site. The amount of bite opening varied according to the surgical design. Direct measurements, radiographs, and histology samples were compared. RESULTS: Linear distraction produced a 4-mm anterior open bite and a Class III malocclusion after 2 weeks of distraction. Segmental rotation produced an 8-mm anterior open bite without complications. Removal of a wedge initiated rotation of the anterior segment. A large wedge (6 mm) produced fibrous union in the distraction site. The amount of bite opening or closure depended on the number of surgical screws and position of the distractor. Serial histologic sections showed bone formation at the rotated, triangular distraction site. CONCLUSION: Bite opening or closure can occur from loss of segment control or by altering surgical design. This information is needed to counter unwanted side effects or to plan segment rotations.

A procedure for stabilization of the infraorbital rim in comminuted malar complex fractures.

A procedure to stabilize comminuted or unstable infraorbital fractures has been presented. This procedure can be of value in those situations in which direct interosseous wiring does not stabilize the fracture or where overlapping is present.

Ameloblastoma of the anterior maxillae.

Few generalizations may be made about the ameloblastoma. Its many varied characteristics may mimic those of many other lesions. The case presented, against all odds and expectations, proved to be highly infiltrative. The use of all available information for accurate diagnosis and sound treatment is stressed. Block resection was found to be the best treatment assuring no recurrence and minimal deformity.