Comparison of part-time and full-time mandibular advancement: enlightenment based on type H vessel coupling osteogenesis

ObjectivesThis study was aimed at resolving the controversy over the wearing time of mandibular advancement (MA) appliances by comparing the differences between part-time and full-time MA (PTMA and FTMA) from the perspective of promoting H-type vessel coupling osteogenesis in the condylar heads.Materials and methodsThirty 30-week-old male C57BL/6J mice were randomly divided into 3 groups: the control (Ctrl), PTMA, and FTMA groups. The mandibular condyles were analyzed by morphology, micro-computed tomography, histological staining, and immunofluorescence staining to investigate the changes of the condylar heads in the PTMA and FTMA groups after 31 days.ResultsBoth PTMA and FTMA models promoted condylar growth and achieved stable mandibular advancement at day 31. However, compared with PTMA, FTMA has the following characteristics. First, new bone formation in the condylar head was detected in the retrocentral region in addition to the posterior region. Second, the condylar proliferative layer was thicker, and the number of pyknotic cells in the hypertrophic and erosive layers was higher. Moreover, endochondral osteogenesis of the condylar head was more active. Finally, the retrocentral and posterior regions of the condylar head had more vascular loops or arcuate H-type vessel coupling Osterix(+) osteoprogenitors.ConclusionsWhile both PTMA and FTMA induced new bone formation in the condylar heads of middle-aged mice, FTMA promoted more osteogenesis by volume and region. Furthermore, FTMA presented more H-type vessel coupling Osterix(+) osteoprogenitors in both the retrocentral and posterior regions of the condylar head.

Automated summary

This study compared the differences between part-time and full-time mandibular advancement (MA) appliances and aimed to promote H-type vessel coupling osteogenesis in the condylar heads. The results showed that full-time MA induced more osteogenesis and vascular structures in both volume and region.