Résumé
Abstract Characterizations of rat mandibular second molar extraction socket with significantly different buccal and lingual alveolar ridge width remain unclear. Objective: To observe alterations in the alveolar ridge after extraction of mandibular second molars, and to examine processes of alveolar socket healing in an experimental model of alveolar ridge absorption and preservation. Methodology: Eighteen Wistar rats were included and divided into six groups regarding healing time in the study. Bilateral mandibular second molars were extracted. The rats with tooth extraction sockets took 0, 1.5, 2, 3, 4 and 8 weeks of healing. Histological observation, tartrate-resistant acidic phosphatase (TRAP) staining, Masson's trichrome staining, immunohistochemical staining and micro-computed tomography (micro-CT) were applied to estimate alterations in the alveolar ridge. Results: Different buccal and lingual alveolar ridge width led to different height loss. Lingual wall height (LH) decreased significantly two weeks after tooth extraction. Buccal wall height rarely reduced its higher ridge width. From two to eight weeks after extraction, bone volume (BV/TV), density (BMD), and trabecular thickness (Tb.Th) progressively increased in the alveolar socket, which gradually decreased in Tb.Sp and Tb.N. LH showed no significant change during the same period. Osteogenic marker OCN and OPN increased during bone repair from two to eight weeks. The reduced height of the lingual wall of the tooth extraction socket was rarely repaired in the later repair stage. Osteoclast activity led to absorption of the alveolar ridge of the alveolar bone wall within two weeks after operation. We observed positive expression of EMMPRIN and MMP-9 in osteoclasts that participated in the absorption of the spire region. Conclusion: Extraction of rat mandibular second molars may help the study of alveolar ridge absorption and preservation. The EMMPRIN-MMP-9 pathway may be a candidate for further study on attenuating bone resorption after tooth extraction.
Résumé
Objective@#To evaluate the osteogenic effect of concentrated growth factor (CGF) combined with deproteinated bovine bone mineral (DBBM) in site preservation using clinical and histomorphometric observations.@*Methods @#A total of 26 patients who needed extraction of affected teeth and received staged implantation after site preservation were selected. The patients were randomly divided into the DBBM group (Bio-Oss was implanted simultaneously after extraction) and CGF+DBBM group (CGF+Bio-Oss was implanted simultaneously after extraction), with 13 patients in each group, and both groups were covered with Bio-Gide collagen membrane. Cone beam computed tomography (CBCT) was performed preoperatively and 6 months later to measure the changes in alveolar bone height and width, and the bone specimens were drilled 6 months after site preservation during implant surgery for histological analyses.@*Results@# CBCT showed that the height and width of alveolar bone were absorbed 6 months after site preservation in the CGF+DBBM and DBBM groups, and the reduction in alveolar ridge width in the CGF+DBBM group was statistically less than the DBBM group (P <0.05). The histomorphometry results showed that the percentage of new bone in the CGF+DBBM and DBBM groups were 35.30% ± 3.56% and 26.38% ± 5.04%, respectively, and the amount of new bone in the CGF+DBBM group was statistically higher than the DBBM group (P<0.05). @*Conclusion @#CGF combined with DBBM is superior to DBBM in maintaining the alveolar bone volume and shape in site preservation, which creates favorable conditions for implant restoration.
Résumé
Objective To observe the clinical effects on prevention of alveolar bone absorption by site preservation after tooth extraction due to periodontitis.Methods The experimental group consisted of 40 patients with 45 extracted teeth due to periodontitis.The fresh sockets were immediately grafted and filled with Bio-oss collagen and Bio-Gide after minimally invasive tooth extraction,while 40 teeth of control group were only treated with cotton balls bitten tightly over the socket for half an hour.Two groups were observed for changes in alveolar bone density by X-ray and cone beam CT (CBCT)after 6 months.Results There were the wound healing and no infection in extraction site of all patients with or without site preservation operation.The gingiva of extraction site was pink and tough in all groups.The alveolar bone loss in regular extraction patients significantly increased in horizontal and vertical aspects by X-ray and CBCT,while site preservation improved the alveolar bone defects (P<0.05).After site preservation for 6 months,CBCT analysis showed that the density of new alveolar bone markedly enhanced compared with regular extraction group.Conclusion The technique of site preservation after tooth extraction due to periodontitis is a method which can prevent and reduce disuse atrophy absorption of the alveolar ridge so that the height and width of the alveolar bone can meet aesthetic requirements.