| Objective: The aim of the present experiment was to study biologic width and morphologic characteristics of soft tissues and bone around implants with different implant-abutment junction, under loaded or unloaded condition. To find out the effect of biologic width in reducing peri-implant crestal bone resorption when using implants with platform switching. It can give an evidence to optimize implant-abutment junction and select implants for clinical application.Methods:In six healthy adult dogs, their second, third, fourth premolars of mandibles were extracted.36 submerged implants were placed after 3 months healing. Divided them randomly into three groups by different implant-abutment junction: A:Ankylos system with platform switching;G:Osstem-GS system with platform switching; U: Osstem-US system with traditional butt-joint.3 months later, second stage surgery was performed to connect healing abutment. Implants located in right were connected with metal crowns and functional loading after 1 month of second stage, while implants located in left were unloaded. The animals were killed after 8 month of functional loading. Sections of bone and soft tissue with dental implant were made for histomorphometrical analysis. GM(the marginal portion of the peri-implant gingiva), aJE(the level of the apical termination of the junctional epithelium, BIC(the marginal level of bone to implant contact), IS(implant shoulder) were located. Measurements were made between GM-aJE(extent of epithelial downgrowth, ED), aJE-BIC(length of connective tissue contact with the abutment and the implant,CTC), GM-BIC(biologic width, BW). The results were analyzed by SPSS 13.0, and it was regarded as statistically significance when P value was less than 0.05.Results:①All implants were judged to be successfully osseointegrated. The success rate is 100%. In the following time, no implants were loose or lost and healthy gingival was seen.②Under functional loading condition, A:ED isl.35±0.37mm, CTC is 1.87±0.32mm, BW is 3.22±0.67mm G:ED is 1.42±0.36mm, CTC is 1.86±0.27mm, BW is 3.28±0.53mm, U:ED is 1.78±0.46mm, CTC is 1.53±0.38mm, BW is 3.31±0.45mm。Under unloaded condition, A:ED is 1.49±0.27mm, CTC is 1.78±0.31mm, BW is 3.27±0.49mm。G:ED is 1.38±0.38mm, CTC is 1.75±0.22mm, BW is 3.13±0.62mm, U:ED is 1.80±0.43mm, CTC is 1.50±0.29mm, BW is 3.30±0.71mm.③Under loaded or unloaded condition, the difference in ED,CTC had statistical significance between group U with traditional butt-joint and group A or group G with platform switching (P< 0.05).④Under loaded or unloaded condition, the difference in BW had no statistical significance between group A, group G and group U (P>0.05).⑤The difference in ED,CTC and BW had no statistical significance between loaded and unloaded condition in each group A, group G and group U (P>0.05).Conclusion:In the present study, we can conclude that:①Biologic width around implants is a stable dimension, but you can find difference in different individuals.②Biologic width around implants with different implant-abutment junction has no relation under loaded or unloaded condition.③Implants with different implant-abutment junction have little effect with biologic width, but it has effect with the attached location of junctional epithelium. Some sections exhibit that aJE attach in abutment or platform of implants in group A and group G with platform switching, aJE attach under implant-abutment junction in group U with traditional butt-joint.④New bone can grow at platform in implants with platform switching. Compared with traditional butt-joint, implants with platform switching show a higher length and a larger width of connective tissue contact as well as a shorter epithelial downgrowth. |
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