Effect of surgical reduction of the tongue on dentofacial structure following mandibular setback.

PURPOSE: The objective of this study was to examine the effect of partial glossectomy on skeletal stability and postoperative changes after mandibular setback. PATIENTS AND METHODS: Sagittal split ramus osteotomy with semirigid fixation was performed in 21 patients with tongue reduction surgery (tongue reduction group) and was performed in 19 patients without tongue reduction (control group). Lateral cephalograms were evaluated preoperatively, immediately postoperatively, and 1 year postoperatively, to analyze the maxillomandibular relation and soft tissue morphology. RESULTS: The results in both groups suggested that posterior and downward movement of the hyoid bone and narrowing of the upper pharyngeal airway at the tongue base were evident immediately postoperatively and rebounded to their original position 1 year after surgery. The tongue reduction had an effect to prevent narrowing of the posterior airway space and a tendency to reduce clockwise rotation of the mandible after the setback, but there was no significant difference between the 2 groups in the horizontal and vertical changes of incisal position at 1 year. CONCLUSION: Adaptation of the hyoid bone position and tongue mass to the altered environment after setback surgery may preclude the necessity for downsizing the tongue against the relapse in patients with normal tongue morphology.

Recombinant human bone morphogenetic protein-2 promotes osteogenesis within atelopeptide type I collagen solution by combination with rat cultured marrow cells.

We evaluated the combination effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) and cultured rat bone marrow mesenchymal stem cells (MSCs) in atelopeptide type I collagen (AC) solution on osteogenesis in a diffusion chamber (DC) to develop a bone substitute having consistent osteogenic capability for clinical applications. The cultured MSCs were obtained by 10-day primary culture of fresh bone marrow cells of Fischer rats. We prepared three groups of DCs: AC solution with rhBMP-2, AC solution with cultured MSCs, and AC solution with rhBMP-2 and cultured MSCs. The prepared combined solutions were injected into DCs, which were subcutaneously implanted into the backs of syngeneic rats. DCs were harvested after 2, 4, or 8 weeks and analyzed for bone-forming capability by determining histological and osteoblastic biochemical markers. De novo bone formation was observed both inside and outside of the membrane filter of DCs in the group of AC solution with rhBMP-2 and cultured MSCs. The alkaline phosphatase activity and osteocalcin content in the group of AC solution with rhBMP-2 and cultured MSCs were significantly higher than those in the group of AC solution with cultured MSCs at any time. These findings indicate that AC aqueous solution is a useful material not only as a carrier of rhBMP-2 but also as a cell-anchorage for differentiation and proliferation of MSCs. Therefore, this study suggests that clinical repairs of bone defects are feasible using injectable AC solution with rhBMP-2 and cultured MSCs as a bone substitute.