Postoperative relapse after mandibular setback surgery with perioperative counterclockwise rotation of the mandibular proximal segment.

OBJECTIVE: This study aimed to evaluate whether the perioperative counterclockwise rotation (CCWR) of the proximal segment (PS) can reduce relapse after mandibular setback surgery. STUDY DESIGN: Patients who underwent less than 1° of bilateral perioperative rotation of the PS were assigned to group I (n = 15). Group II (n = 14) included patients who showed greater than 1° of perioperative CCWR bilaterally. To evaluate the PS rotation and the relapse, three-dimensional computed tomography (CT) and lateral cephalography scans were analyzed. RESULTS: Even with significantly different perioperative CCWR of the PS (.07 ± .53° vs -3.47 ± 1.55°), the relapse was not significantly different between group I (1.96 ± 1.15 mm) and group II (1.81 ± .92 mm). However, postoperative CCWR of the PS was significantly greater in group I. The relapse was not influenced by the amount of setback. CONCLUSIONS: A small degree of relapse is expected after mandibular setback surgery, even with perioperative CCWR of the PS.

Effect of mesenchymal stem cells and platelet-derived growth factor on the healing of radiation induced ulcer in rats.

Radiation-induced skin ulceration is a frequent complication of radiation therapy. This study investigated the effects of rat mesenchymal stem cells (rMSCs) and platelet-derived growth factor (PDGF) on the healing of radiation-induced soft tissue injury. Sprague-Dawley rats (n=17) were irradiated on the right and left buttocks with a single dose of 50 Gy. The right buttocks were administered with phosphatebuffered solution as a control. The left buttocks were administered with either rMSCs (2×106 cells), PDGF (8 µg), or PDGF combined with rMSCs. Administration was done at three weeks after irradiation. Wound healing was analyzed by calculating the percentage of residual ulcerated skin area compared to the total irradiated area during the five week healing period after administration. Modified skin scores were also assessed. Finally, skin lesions were histologically evaluated. More than 40% of the irradiated skin area within the irradiated zone underwent ulceration within 16 days postirradiation, with peak ulceration exceeding 50% around three weeks post-irradiation. Administration of rMSCs or PDGF alone did not confer any significant healing effect. The combined rMSCs+PDGF treatment significantly reduced the wound size compared with the nontreated control up to two weeks postinjection. Regarding the histological examination, lesions administered with PDGF (either alone or mixed with rMSCs) resulted in a greater deposition of highly organized collagen fibers throughout the dermis layer, compared with the control. In conclusion, the combined administration of rMSCs and PDGF efficiently enhanced the healing of radiation-induced skin ulceration.

Effect of bone marrow-derived stem cells and bone morphogenetic protein-2 on treatment of osteoradionecrosis in a rat model.

PURPOSE: We investigated the effect of rat mesenchymal stem cells (rMSCs) and bone morphogenetic protein-2 (BMP-2) on the osseous healing of osteoradionecrosis in the rat mandible, depending on application time. MATERIAL AND METHODS: One week after irradiation (30 Gy) on the right mandible, all molar teeth were extracted. In Group 1 (n = 25), rMSCs and/or BMP-2 carried with hydrogel were applied immediately after surgery. In Group 2 (n = 25), application was done 4 weeks after surgery, after the occurrence of osteoradionecrosis. No hydrogel (n = 5), hydrogel alone (n = 5), hydrogel with 2 × 10(4) rMSCs (n = 5), hydrogel with 10 µg of BMP-2 (n = 5), or hydrogel with 10 µg of BMP-2 and 2 × 10(4) rMSCs (n = 5) was applied. Micro-CT data of bone healing were collected at 4 weeks post-application. RESULTS: In Group 1, BMP-2 was effective in increasing both bone volume (BV) and bone mineral density (BMD), whereas rMSCs were not. In Group 2, the combined application of rMSCs and BMP-2 significantly increased BMD and BV compared to values in the groups without hydrogel and with hydrogel alone. CONCLUSION: Osseous healing after post-irradiation trauma in rats was enhanced immediately after dentoalveolar trauma by application of BMP-2, whereas the combined application of rMSCs and BMP-2 was most effective after osteoradionecrosis occurred.