Correlations between clinical parameters in implant maintenance patients: analysis among healthy and history-of-periodontitis groups

BACKGROUND The pathophysiology and pathology of peri-implantitis remain unclear; however, its similarity to periodontitis has been described. The evaluation of peri-implant tissue and the diagnostic criteria of peri-implant disease are not currently standardized as they are for periodontitis. In this study, we evaluated clinical parameters during the implant maintenance period to determine significant correlations between these parameters. METHODS We examined 55 implant patients at the time of maintenance visits between April and September 2016 and classified patients into a healthy group (H) and a history-of-periodontitis group (HP). For each implant, we evaluated the modified plaque index, probing pocket depth, and bleeding on probing as clinical parameters. Statistical analyses were performed with Spearman's rank correlation coefficient. RESULTS A total of 130 implants were assessed. The mean time since implant placement was 6 years and 6 months. The prevalence of implant-based peri-implantitis was 10.8% of all the implants. All cases of implant-based peri-implantitis came from the HP group, and many were present in patients with a history of severe periodontitis. The probing pocket depth around the implant was significantly greater in the HP group than in the H group. We found weak positive correlations between the probing pocket depth and bleeding on probing (r s  = 0.401, p < 0.05) in the H group and between the probing pocket depth and bleeding on probing (r s  = 0.241, p < 0.05) and the modified plaque index (r s  = 0.228, p < 0.05) in the HP group. CONCLUSIONS Our findings suggest that probing pocket depth and bleeding on probing as clinical parameters are important indicators for the diagnosis of peri-implant disease during the maintenance period among healthy and history-of-periodontitis groups.