Morphological and Histological Changes in the Mandibular Condyle after Plate Removal in Experimental Models of Short- and Long-term Mandibular Lateral Displacement

Abstract

We conducted an in vivo study to clarify the mechanics of the mandibular bone and condyles in pediatric patients with mandibular functional deviation. We experimentally caused lateral displacement of the mandible in 4-week-old rats by attaching a plate to the teeth for 4 (short-term group: ST group) or 12 weeks (long-term group: LT group), and immunohistochemically investigated the pattern of appearance of matrix metalloproteinase-1 (MMP-1), vascular endothelial growth factor (VEGF), and connective tissue growth factor (CTGF) to investigate the changes in the cartilage matrix constitution during the recovery of the condylar morphology. Furthermore, the morphology was observed using micro (μ) -CT.After plate removal, the MMP-1 expression significantly decreased in the both groups. Furthermore the expressions of VEGF and CTGF were increased in the ST group compared to those observed in the LT group. In terms of the morphometry, mandibular asymmetry and deformity of the condyle were noted immediately after removal in the both groups. The mandibular morphology markedly recovered in the ST group compared to that in the LT group. This indicates that correction of occlusal abnormalities during an early stage leads to recovery of the normal mandibular configuration.