Loading of the Condylar Cartilage Can Rescue the Effects of Botox on TMJ.

The purpose of this study is to evaluate whether the effects of botulinum neurotoxin (botox) injection into the masseter in the mandibular condylar cartilage (MCC) and subchondral bone could be rescued by compressive loading of the temporomandibular joint (TMJ). Twenty-four 6-week-old female mice (C57BL/6J) were used. Mice were divided in three groups: (1) Botox (n = 8); (2) Botox plus loading (n = 8); (3) Pure control (n = 8). Bone labels (3 and 1 day before sacrifice) and the proliferation marker EdU (2 and 1 day before sacrifice) were intraperitoneally injected into all groups of mice. Condyles were dissected and examined by micro-CT and histology. Sagittal sections of condyles were stained for TRAP, alkaline phosphatase, EdU, TUNEL, and toluidine blue. In addition, immunostaining for pSmad, VEGF, and Runx2 was performed. Bone volume fraction, tissue density, and trabecular thickness were significantly decreased on the subchondral bone of botox-injected side when compared to control side and control mice, 4 weeks after injection. Furthermore, histological analysis revealed decrease in mineralization, matrix deposition, TRAP activity, EdU, and TUNEL-positive cells in the MCC of the botox-injected side, 4 weeks after injection. However, compressive loading reversed the reduced bone volume and density and the cellular changes in the MCC caused by Botox injection. TMJ compressive loading rescues the negative effects of botox injection into the masseter in the MCC and subchondral bone.

Clear aligner mandibular advancement in growing patients with Class II malocclusion.

Treatment effects occurring during Class II malocclusion treatment with the clear aligner mandibular advancement protocol were evaluated in two growing patients: one male (12 years, 3 months) and one female (11 years, 9 months). Both patients presented with full cusp Class II molar and canine relationships. Intraoral scans and cone-beam computed tomography were acquired before treatment and after mandibular advancement. Three-dimensional skeletal and dental long-axis changes were quantified, in which the dental long axis was determined by registering the dental crowns obtained from intraoral scans to the root canals in cone-beam computed tomography scans obtained at the same time points. Class II correction was achieved by a combination of mandibular skeletal and dental changes. A similar direction of skeletal and dental changes was observed in both patients, with downward and forward displacement of the mandible resulting from the growth of the mandibular condyle and ramus. Dental changes in both patients included mesialization of the mandibular posterior teeth with flaring of mandibular anterior teeth. In these two patients, clear aligner mandibular advancement was an effective treatment modality for Class II malocclusion correction with skeletal and dental effects and facial profile improvement.