Development of a new three-directional distractor system for the correction of maxillary transverse and sagittal deficiency

Biomechanical analysis of teeth movement during the repair of mandibular defects using transport disk distraction osteogenesis

INTRODUCTION

Teeth movement or rotation is one of the complications of mandibular defect repair using transport disk distraction osteogenesis (TDDO). However, the mechanical reasons are not clearly understood.

MATERIAL AND METHODS

To evaluate the biomechanical factors associated with teeth movements during mandibular defect repair with TDDO, a finite element model created from computed tomographic images of the human mandible was adopted to evaluate teeth displacement and the Von Mises stress distribution on the periodontal ligament resulting from the transport disk for teeth subjected to TDDO loading.

RESULTS

Under a displacement of 0.5 mm to the fixed arm of the transport disk, the teeth on the disk moved away from the distraction. The stress on the periodontal ligament was highest (60 KPa) around the distal neck. Upon the application of 150 g of resistance, the entire tooth moved in the same direction and the isoline gradient was almost parallel to the long axis of the tooth. Although the stress was distributed similarly; it decreased to 0.117 KPa geometrically.

DISCUSSION

When mandibular defects are repaired with TDDO, the transport disk and anti-distraction forces contribute to the reversal movement or rotation of the teeth, which may become immobility when antagonistic forces are applied in the same direction.

Facial soft tissue changes and volumetric analysis of upper airways in patients undergoing surgically assisted rapid maxillary expansion using a transpalatal distractor

OBJECTIVE

To verify changes in facial soft tissue using the RadiANT-DICOM-viewer and Dolphin Imaging software, through linear measurements of tomographic points in a 3D reconstruction of the face and volumetric evaluation with three-dimensional measurements of the upper airways of patients with transverse maxillary discrepancy undergoing Surgically Assisted Rapid Maxillary Expansion (SARME).

METHODS

Retrospective, transverse, and descriptive study, through the analysis of computed tomography scans of the face of patients with transverse maxillary discrepancy, treated from July 2019 to December 2022. The sample consisted of 15 patients of both sexes, aged 21-42 years old, who underwent surgically assisted rapid maxillary expansion using the transpalatal distractor. Analysis was performed through linear, angular, and three-dimensional measurements in millimeters, in the preoperative and late four-month postoperative period, in frontal 3D tomographic images of the face, in the region of the width of the nose and alar base and also angular measurement in the lateral tomography for the angle nasolabial and upper airways of rhinopharynx, oropharynx and hypopharynx.

RESULTS

There was an increase in nasal width with an average of 1.3467mm and an increase in the alar base with an average of 1.7333mm. A significant difference was found in the pre- and postoperative assessments of the measurements of nasal width, alar base and nasolabial angle, as well as the upper airways in all their extension. The results favour a better understanding of the professional and the patient regarding the diagnosis and management of patients with transverse maxillary width discrepancies.

CONCLUSION

Although our study shows an increase in soft tissues after SARME, no aesthetic changes are observed clinically, and all patients report significant respiratory improvement. SARME may therefore contribute to the improvement of professionals working in the field of oral and maxillofacial surgery and orthodontics.

LEVEL OF EVIDENCE

Level 4.