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Objectives: The objectives of this study were to determine whether a new degradable synthetic barrier membrane (Vivosorb (R)) composed of poly(DL-lactide-epsilon-caprolactone) (PDLLCL) can be useful in implant dentistry and to compare it with collagen and expanded polytetrafluoroethylene (ePTFE) membranes.Material and methods: In 192 male Sprague-Dawley rats, a standardized 5 mm circular defect was created through the right angle of the mandible. New bone formation was evaluated by post-mortem microradiography and micro-CT (mu CT) imaging. Four groups (control, PDLLCL, collagen, ePTFE) were evaluated at three time intervals (2, 4, and 12 weeks). In the membrane groups the defects were covered; in the control group the defects were left uncovered. Data were analysed using a multiple regression model.Results: New bone formation could be detected by post-mortem microradiography in 130 samples and by mu CT imaging in 112 samples. Bone formation was progressive in 12 weeks, when the mandibular defect was covered with a membrane. Overall, more bone formation was observed underneath the collagen and ePTFE membranes than the PDLLCL membranes.Conclusions: In contrast to uncovered mandibular defects, substantial bone healing was observed in defects covered with a PDLLCL membrane. However, bone formation in PDLLCL-covered defects tended to be less than in the defects covered with collagen or ePTFE. The high variation in the PDLLCL samples at 12 weeks may be caused by the moderate adherence of this membrane to bone compared with collagen. These results indicate that further study is needed to optimize the properties of PDLLCL membranes.

Whether low intensity pulsed ultrasound therapy stimulates osteogenesis in mandibular distraction was investigated in a double-blind trial. Nine patients underwent a vertical mandibular distraction over a distance of 5.1 +/- 1.2 mm. Ultrasound or placebo therapy was started daily from the first day of distraction. After 46 +/- 8.1 days consolidation, two endosseous implants were inserted and a transmandibular biopsy was taken. Ultrasonographs were taken regularly to follow osteogenesis inside the gap. There were no complications during the 44 +/- 7.1 months of follow-up. Microradiographic measurements of the biopsies revealed no differences in the area of mineralized tissue in the distraction gap. The cranially distracted bone segment appeared significantly more radiolucent than the caudal bone. Histological examination showed large lacunae inside the cranially distracted bone segment, filled with clusters of osteoclasts and surrounded by clear tetracycline double labels. Within the distraction gap, woven bone was present, with no apparent differences between the treatment groups. Ultrasonographic follow-up revealed that osteogenesis inside the distraction gap progresses from 4 to 20 weeks post distraction, with no differences between the ultrasound and the placebo groups. In summary, ultrasound treatment does not appear to stimulate bone formation in the severely resorbed vertical distracted mandible.

Contains fulltext : 80937.pdf (Publisher’s version ) (Closed access) Vivosorb is a new degradable membrane composed of poly(DL-lactide-epsilon-caprolactone) (PDLLCL). The aim of this study was to appraise its performance in guided bone regeneration procedures. In 192 rats a 5.0 mm defect was drilled in the mandibular angle. The defects were covered with a membrane (PDLLCL, collagen, or expanded polytetrafluoroethylene (ePTFE)) or left uncovered (control). Defect closure, mineralization and thickness of the new bone were assessed by means of transversal microradiography at three different time intervals (2, 4 and 12 weeks). The data were analysed using multiple regression analyses. The regression analyses showed significant effect modification between time and collagen and time and ePTFE for mineralization of the newly formed bone. For defect closure and bone thickness all membrane-treated groups showed effect modification between time and membrane; these effects were more significant and larger in the collagen and ePTFE groups. In the non-treated controls no effect modification was observed. The membrane groups showed significantly better results than the control groups. The ePTFE and collagen membranes performed equally well and better than the PDLLCL membrane during this experiment. It was concluded that a PDLLCL membrane is not suitable for clinical application in its current form.