| Nowadays, guided tissue regeneration (GTR), a treatment modality used to facilitate periodontal regeneration of furcation defects, is widely applied in clinical situations. Numerous clinical studies have documented that the expanded polytetrafluoroethylene (e-PTFE) membrane is the standard barrier membrane in GTR. Since this barriers material is non-resorbable, a second surgical procedure is required for its removal. Although little is known about the definitive time for removal of the membrane, it is likely that a membrane which is removed too early or to late may disturb the newly formed regenerated tissue, leading to limited success. Ideally, an objective means of monitoring the time for removal of the membrane would result in great success for this treatment modality. We carried out histological evaluation and biochemical analysis of regeneration tissue in defect areas after the GTR in order to seek an appropriate stay period of the barrier membrane after GTR.The study included two parts:Part 1: Experimental class II furcation defects preparation in mongrel dogs.1. Methods: Full-thickness mucoperiosteal flap were elevated and furcation lesions (6-millimeter in height, 6-millimeter in width, 3-millimeter in depth) were surgical created in all second, third and fourth premolar teeth of mandibular area of four mongrel dogs. One side flaps of the jaws were sutured directly, the other side were sutured after the defects filled with heat-softened gutta-percha. The animals were sacrificed at 4, 6, 8 and 10 weeks, and routine histologic processing were performed.2. Results: After 4 weeks of the surgical, the repaired tissues observed in defects areas of no gutta-percha group were cemetocytes which volume augmented greatly and the cemetoids. A few new alveolar bone were found after 6 weeks of the same group. As time going on, there were more new alveolar bone and more physiological remodeling observed, and, after ten weeks, the regeneration tissues of periodontal become stabile. The other groups were observed diffuse inflammatory cells, forming periodontal pockets after 4 weeks, abscesses in subgingival tissue after 8 weeks and bone absorption after 10 weeks.3. Conclusion: These results indicate that an animal model of experimental grade II furcation defects may be founded by surgically created and combined with local irritations.Part 2: A study of the stay period of e-PTFE membrane after periodontal treatment with GTR in class II furcation defects in dogs. In this part we compared the experimental group with the control group by histological evaluation and biochemical analysis.1. Methods: Class II furcation defects were created in 9 mongrel dogs according to the foregoing part before the flap operation and GTR therapy were carried out 6 weeks later. Histological evaluation and biochemical analysis were done at4. 6, Sweeks following GTR treatment. Mean regenerate periodontal tissues in defect areas were measured, and glycosaminoglycan in gingival cervical fluid (GCF) and new alveolar bone were detected.2. Results: In the GTR treatment groups, the parameter of periodontal regeneration between 4 and 6 weeks after the therapies were significantly different. Superior periodontal regeneration tissues were found 6 weeks after GTR, but in 6 and 8 weeks, there were no significantly differences. In addition, glycosaminoglycan in GCF increased significantly after 4 weeks following the treament and declined distinctly at 6 weeks in the same groups. Glycosaminoglycan in new alveolar bone also declined distinctly at 6 weeks in the GTR treament groups.3. Conclusion: On periodontal GTR healing of furcation involvement, it is need 6 weeks at least to maintain the barrier membrane stay in the furcation place. Moreover, the glycosaminoglycan's level in GCF may present an assist in estimating the mature degree of periodontal regenerate tissue.The results in our researches demonstrated that:1. When it is need to study the therapies of class II fur... |
PDF Full Text Request