Could cytokine levels in the peri-implant crevicular fluid be used to distinguish between healthy implants and implants with peri-implantitis? A systematic review.

BACKGROUND AND OBJECTIVE: Despite investigative efforts to identify the levels of different types of cytokines in the peri-implant crevicular fluid (PICF), the efficacy of these biomarkers in assisting the diagnosis of peri-implantitis is still undetermined. This systematic review aimed to answer the following question: "Could cytokine levels in the PICF be used to distinguish between healthy implants and implants with peri-implantitis?" MATERIAL AND METHODS: This review was conducted and reported in accordance with the PRISMA statement. The MEDLINE and EMBASE databases were searched from 1990 up to and including March 2015, using MeSH terms and other keywords. Additional publications were searched using a hand search of reference lists of relevant studies. Titles and abstracts were screened and papers that fulfilled eligibility criteria were assessed. RESULTS: Out of 1212 titles, 18 studies reporting the levels of nine different cytokines were included. Proinflammatory cytokines [interleukin (IL)-1ß, IL-6, IL-12, IL-17 and tumor necrosis factor-α) were the cytokines studied most commonly, followed by anti-inflammatory cytokines (IL-4 and IL-10), osteoclastogenesis-related cytokines (RANKL) and chemokines (IL-8). Nine studies reported statistically significantly higher levels of proinflammatory cytokines in the PICF of implants with peri-implantitis than in the PICF of healthy implants. Most studies did not find any significant differences in the PICF levels of anti-inflammatory cytokines and RANKL between healthy implants and implants with peri-implantitis. IL-8 was the only chemokine studied and its levels did not differ significantly between healthy and diseased implants. The studies differed greatly in the manner in which they reported the results (e.g. concentrations or total amounts) and in the exclusion of confounders, such as smoking. CONCLUSION: The results of this systematic review indicate moderate evidence in the literature to support that implants with peri-implantitis present higher levels of proinflammatory cytokines in the PICF than do healthy implants. Evidence regarding the PICF levels of anti-inflammatory cytokines, osteoclastogenesis-related cytokines and chemokines as possible predictors of peri-implantitis is too limited.

Photo-elastic investigation of influence of dental implant shape and prosthetic materials to patterns of stress distribution.

AIM: Occlusal loading has to be considered a key factor influencing bone resorption due to the stress transmitted to surrounding tissues by the implant-abutment structure. The aim of this study was to evaluate, through a photo-elastic investigation, the patterns of tensions distribution of two different implant shapes, which were cylindrical and conical. METHODS: A 100N load was applied to two implant-abutment structures (with and without a metal-ceramic crown) incorporated in photo-elastic resin. Modification in light refraction were recorded and analyzed through a computerized software. Measurements of stripe extension and position were evaluated. RESULTS: Stress distribution around tapered implant was evaluated to be more uniform than in cylindrical one which demonstrated a high stress concentration at the more cervical region and in the apical region. The presence of a metal-ceramic crown caused an increase in tensions at the implant-resin interface. CONCLUSION: Conical implants distributed stresses to a larger and well-defined volume of resin and this can cause a decrease of forces acting at the interface. This could be due to the "wedge effect" of this fixture shape which could be considered superior in terms of stress distribution than cylindrical one.