Ultrasound and Mesenchymal Stem Cells: Effects on Mandibular Growth

Objective: To establish the effects of Mesenchymal Stem Cell (MSCs) transplantation in the  TMJ region of Sprague-Dawley rats treated with Low Intensity Pulsed Ultrasound (LIPUS) using Cone Beam Computed Tomography (CBCT) 3D reconstructions. Methods: 26 male rats (20 days) were divided into 5 groups: A, LIPUS-stimulated; B, MSCs injection, C; LIPUS+MSCs; D, Medium injection; E, untreated controls. The treatments were performed at the left side. LIPUS was aplied for 20 minutes daily (50mW/cm2 ,1MHz, 0,2-millisecond pulses). MSCs were injected  in the TMJ region suspended in αMEM (injected volume: 1x106cls/kg). CBCTs were carried out and 3D reconstructions cephalometrically analyzed. Statistics: paired studentxs t-test  and ANOVA-Scheffé. Results: statistically significant differences (p≤0,05) were observed within groups (left v/s right) for condilar width in groups A, B and C, left condyles displaying greater values. For sagittal condylar length, group A had greater values at the left side (p<0.002), and the opposite occurred in group C (p<0.007). In group D, a greater mandibular length was observed on the control (right) side (p<0.03). Between-group comparisons (between left sides of different groups) resulted in significant differences in sagittal condylar length (p<0.001), condilar width (p<0.05) and dental midlines (p<0.01). Group A displayed greater condylar dimensions and its lower midline deviated to the right relative to controls.   Conclusions: LIPUS application on the TMJ region of growing rats may favour sagittal condylar development; while LIPUS and MSCs, would favour transversal condylar growth. The MSC transplantation model utilized would negatively affect sagital condylar growth, probably due to the associated surgical trauma.