A Comparison Of Osteogenesis Efficiency Between Using A Single Layer Of Membrane And A Dual Layer Of Membrane For Ridge Preservation In Class Ⅱ Extraction Sockets Of Beagle Dogs.

Purpose: The present study was aimed to utilize a canine model to observe the effect of ridge preservation on reconstruction of defective buccal bone wall in fresh Class II extraction sockets, and to compare the osteogenic efficiency between using a single layer of membrane and a dual layer membrane(d PTFE placed over collagen) for ridge preservation in fresh Class II extraction sockets.Methods: In sixteen beagle dogs bilateral mandibular first premolars were atraumatically extracted. The buccal bone walls of extraction sockets are grinded to build the model Class II extraction sockets. The extraction sockets are randomly divided into four groups:(a) Control–Socket alone;(b) Anorganic bovine bone(Bio Oss) in the alveolum, socket covered with d PTFE membrane and sutured over the alveolum;(c) Anorganic bovine bone(Bio Oss) in the alveolum, socket covered with collagen membrane and sutured over the alveolum;(d) Anorganic bovine bone(Bio Oss) in the alveolum and covered with dual layer(d PTFE membrane placed over collagen membrane), and sutured over the alveolum. After the follow up of 12 weeks, the animals were sacrificed. The bone blocks in bilateral mandibular first premolar area are incised for histological examination. The measured indexes of the bone blocks involves the height difference between buccal and lingual alveolar ridge and buccal alveolar ridge thicknes. The data were statistical analysed through SPSS 13.0.Results: The success rate of operation is 96.88 %. The collagen membrane of a sample in group C was exposed, the mucosa in the operation area of the rest of the cases was well healed. After the follow up of 12 weeks, the buccal bone walls of the cases ingroup A were absorbed remarkably. The heigh and width of the alveolar ridge was declined remarkably. The buccal bone walls of the rest of cases were absorbed, but the changing was less remarkably. The height difference between buccal and lingual alveolar ridge of group A was significantly higher than the rests, and the buccal alveolar ridge thicknes of group A was significantly lower than the rests. The height difference between buccal and lingual alveolar ridge of group B was significantly higher than the height difference of group C and group D. The height difference between buccal and lingual alveolar ridge of group C was significantly higher than the height difference of group D. The buccal alveolar ridge thicknes of group B and C was significantly lower than the thicknes of group D, while the difference of buccal alveolar ridge thicknes between group B and group D was not significant.Conclusions: 1. When used in Class II extraction sockets, the ridge preservation could help to reconstruct the defective buccal bone wall. 2. In Class II extraction sockets, the osteogenic efficiency of using a dual layer membrane(d PTFE placed over collagen) for ridge preservation is more effective than using a single layer membrane. 3. When using a single layer membrane for ridge preservation in Class II extraction sockets, the d PTFE membrane is more beneficial to the vertical reconstruction of defective buccal bone wall than the collagen membrane.