Azita Tehranchi; Hossein Behnia; Sepideh Soheilifar
Abstract
Background and aim: Bilateral mandibular distraction osteogenesis (BMDO) has been suggested as a suitable method for correcting severe mandibular deficiencies. The purpose of this study was to evaluate the cephalometric changes of patients undergoing BMDO.Materials and methods: Seven patients were selected ...
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Background and aim: Bilateral mandibular distraction osteogenesis (BMDO) has been suggested as a suitable method for correcting severe mandibular deficiencies. The purpose of this study was to evaluate the cephalometric changes of patients undergoing BMDO.Materials and methods: Seven patients were selected for BMDO, all suffering from severe mandibular retrognathia as a result of previous trauma. Pre-treatment (T1), post-treatment (T2) and follow up (T3) cephalograms were obtained. The changes in skeletal and soft tissue parameters were assessed by paired t-test within two time intervals (T1-T2 and T2-T3). Results with a P value <0.05 were considered statistically significant. Results: In patients treated by extra-oral distractor, BMDO improved jaw relationships by increasing SNB (12.1˚) and mandibular length (22.5mm) and decreasing ANB (10.3˚) and Wits (17.2mm). Lower facial height increased significantly (4.5mm). Dental relationships were changed by increasing interincisal angle (24.8˚) and decreasing IMPA (23.2˚) and overjet (8.8mm). Reduction in the distance between upper and lower lip to E-line led to changes in the soft tissue profile. Airway space analysis revealed an increase in the nasopharyngeal space (Nph2) (4.7 mm), the oropharyngeal space (Oph2) (5.4mm) and the posterior airway space (PAS) (9mm). The available cases remained stable during the follow up period.
Conclusion: BMDO improved maxillomandibular discrepancy by lengthening mandibular body. Lower anterior facial height was increased significantly. Lip prominency relative to the nose and the chin was decreased and dental relationships were corrected by the treatment. DO procedure significantly improves the pharyngeal spaces.
Azita Tehranchi; Hossein Behnia; Majid Heidarpour; Bahman Toutiaee; Mohammad Javad Khosropour
Abstract
Aim: Analyzing the changes made during distraction osteogenesis (DO) in asymmetric mandibles.Materials and methods: This study was performed on a three dimensional model of a desiccated mandible, based on a finite element method. The distraction devices were placed with an angle of 90, 60 or 30 degrees ...
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Aim: Analyzing the changes made during distraction osteogenesis (DO) in asymmetric mandibles.Materials and methods: This study was performed on a three dimensional model of a desiccated mandible, based on a finite element method. The distraction devices were placed with an angle of 90, 60 or 30 degrees to the oblique surgical cut. The directions of the pins were such that the 30 and 60 degree pins were placed in a counterclockwise direction relative to the perpendicular pin. The distractors were opened for 15 and 30 mm. The amount and direction of movement of proximal and distal segments and the displacement of pogonion were evaluated in all three planes of space.
Results: In the distal segment, the maximum change in pogonion was seen in 30 degree angle. In the proximal segment, if the distraction device was used with 90 degree angle, the condylar process rotated in the clockwise rotation. In 30 degree angle, this process rotated in a counterclockwise direction and the minimum rotation was seen in 60 degree angle.Conclusion: If gonial angle is to be augmented in a downward direction maximally, the angle of distraction device to the surgical cut is critically important (that is, it should be perpendicular to surgical cut). By use of perpendicular mode, ramus slops more posteriorly. It is better to use the distraction pin with a thirty degree angle if the ramus needs to be uprighted. The oblique surgical cut, irrespective of the distraction pin angle, increases the anterior facial height.
