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Limited marginal bone loss in implant-supported fixed full-arch rehabilitations after 5 years of follow-up.

PURPOSE
The aim of the present study was to evaluate the 5-year results in terms of marginal bone level (MBL) around implants supporting fixed full-arch metal-ceramic restorations in a series of cases of patients who had lost their teeth in that dental arch because of severe periodontal disease.


MATERIAL AND METHODS
A retrospective cohort study was designed to evaluate the 5-year MBL results of OsseoSpeedTM Astra Tech TX implants with internal tapered conical connection. Age, gender, bone substratum, smoking habits, history of periodontitis, and prosthetic features were recorded. Mixed linear model was used to determine the influence of the different variables on MBL.


RESULTS
In this series, a total of 160 implants placed in 19 patients were evaluated. No implant failure was reported during the 5 years of follow-up. Only 14 (8.75%) implants had more than 2 mm of MBL. Abutment height, F(3,142)=6.917, p<0.001), and implant diameter, F(1,141)=15.059, p<0.001, were determined to be statistically associated with MBL. No other effect was significant. Pairwise comparisons showed that MBL was larger for abutment height=1 (MBL=-0.987, SE=0.186) compared to the remaining heights (-0.335 (0.171), -0.169 (0.192) and -0.247 (0.267), 2, 4 and 6mm, respectively). MBL was larger for narrow (-0.510, SE= 0.169) than for wide implants (-0.364, SE=0.190).


CONCLUSION
The current study demonstrates that the vast majority of internal conical connection implants supporting fixed full-arch metal-ceramic restorations do not suffer from relevant MBL after 5 years in function. Particularly, those implants with transmucosal abutments longer than 2 mm show less than 0.5 mm from the implant shoulder to the marginal bone.