Risk factors associated with the bone loss around implants and development of peri-implantitis

Abstract

Objectives: The objective of this project is to make up the basis for this work examine the roles of various factors in marginal bone loss (MBL) around implants and in the development of Peri-implantitis (PI) in a variety of clinical scenarios and populations. A multitude of parameters related to the implant and to the patient were assessed. Materials and Methods One meta-analysis and three retrospective studies gathering long term data acquired from the physical and electronic charts of patients at the university of the dental school of the university Michigan and University of Granada school of dentistry were performed. In study #1, 165 partially edentulous adults (77 men, 88 women) aged 30– 91 with ≥2 years of follow-up upon implant restoration were included. Implants with ≥1 interproximal thread exposed (no bone-to-implant contact) (n = 98, 35%) constituted the test group and those without exposed threads (n =182, 65%) the control group. Descriptive, binary, and multivariate regression analyses were evaluated for goodness of fit. Wald tests were used to evaluate for significance set at 0.05. In study #2 retrospective analysis of patients with a history of periodontitis (PR) who received nonsurgical and, if indicated, surgical corrective therapy prior to implant placement was performed. Periodontitis stage and grade were determined for each included patient based on data from the time of initiation of active periodontal therapy. Cox Proportional Hazard Frailty models were built to analyze the correlation between stage and grade of periodontitis at baseline with implant failure, as well as occurrence and severity of PI. In study #3, 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. Finally, in study #4 a systematic electronic and manual search of randomized or non- randomized controlled or noncontrolled clinical trials was conducted. Qualitative review, quantitative meta-analysis, and trial sequence analysis (TSA) of implants inserted at sites with <2 mm or ≥2 mm of KMW were analyzed to compare all the predetermined outcome variables. The level of evidence concerning the role of KMW in peri-implant health was evaluated via the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system guide. Variables on marginal bone loss. Results: Firstly, in Study #1 we showed that exposed (with no BIC) implant threads was the main risk factor for PI with the PI risk almost 8 (7.82) times greater than in patients with implants with no exposed threads. This risk increased almost 4-fold (3.77 times) with each additional thread exposed. Splinting increased the risk of PI by 3.49 times. Importantly, no other potentially confounding modifiable risk indicator was identified as statistically significant in incident PI in multivariate and univariate analyses, including a history of periodontitis (PR) (yes/no), despite the multitude of macro- or micro-surface design variables included. Secondly, the history PR present at baseline in these maintenance-compliant patients was classified according to the 2017 World Workshop case definitions,we still found no correlation between PR stages or grades and neither prevalence nor incidence of PI at either implant- nor patient-levels. However, although the implant failure rate increased from stage I/II (0%) to stage IV (6.5%), this trend was not statistically significant, but there was a statistically significant increase in implant failure from grade A (0%) to grade C (5.9%). Thirdly, we studied patients with at least one completely edentulous arch who had lost their teeth due to severe PR and had received implant-supported fixed full-arch metalceramic restorations. We found that the implants performed well and experienced limited MBL, even in patients with prior severe PR. This was even the case in one patient who had full-arch rehabilitation in both edentulous jaws. Finally, in Study #4 we explored the soft tissue adjacent to the implants via a systematic review and meta-analysis. The approach was necessitated by the lack of sufficient information available for harvest from dental charts in a retrospective study design. Specifically, we focused on KMW and concluded that compared to implants with ≥2 mm KMW, implants associated with <2 mm KMW did not exhibit increased MBL; and there is insufficient evidence for KMW <2 mm being a risk factor for incident PI. In a recent systematic review and meta-analysis, <2 mm KMW was found to be associated with increased rates of MBL and PI. Despite the conclusion of an association only, which is not a causal relationship, the authors still state “Hence, in the cases lacking KT, clinicians might consider soft-tissue grafting to increase KT to promote peri-implant soft- and hard-tissue stability.” Conclusion implant thread exposure after the initial expected bone remodeling was the only statistically significant potential risk indicator for incident PI that was identified. No statistically significant association between periodontitis severity (staging) and rate of progression (grading) at baseline, with prevalence of peri-implantitis was found. However, when peri-implantitis was present, increased severity of marginal bone loss and probability of implant failure were found for grade C patients. Most of the internal conical connection implants supporting fixed full-arch metal-ceramic restorations in patients who lost all their teeth in that dental arch mostly as a consequence of severe periodontitis do not suffer from relevant MBL after 5 years in function. Particularly, those implants with transmucosal abutments longer than 2 mm show, in average, less than 0.5 mm from the implant shoulder to the marginal bone. Finally, implants associated with <2 mm KMW did not exhibit increased MBL, REC and PD compared to implants with ≥2 mm. Peri-implant KMW <2 mm was associated with increased mPI and more discomfort after toothbrushing. Low level of evidence was determined for the findings related to the outcome measures PD, mPI and MBL, and very low level of evidence was determined for the findings related to the outcome measures REC, CAL and PROMs. The level of evidence regarding implant survival rate and incidence of periimplantitis could not be determined due to data scarcity.