INTRODUCTION

Although dental implants have been reported to have fairly high survival rates of 95.7% at 5 years and 92.8% at 10‐years, it is also known that progressive marginal bone loss and peri‐implantitis remain a significant potential complication. The 2012 European academy of osseointegration (EAO) consensus report estimated the prevalence of peri‐implantitis to be at 10% of implants and 20% of patients, 5 to 10 years after implant placement. However, there was a wide range in reported prevalence, arising, in part, due to variable implant designs and variability in the thresholds applied for bone loss and soft tissue analysis.

The clinical definition of peri‐implantitis, according to the Sixth European workshop on periodontology, refers to the presence of redness, swelling of mucosa, bleeding and/or suppuration, deepening of pockets adjacent to the implant and loss of supporting bone. In practice, not every study includes pocket depth measurements, but most studies use marginal bone loss and soft tissue condition as parameters in the classification of peri‐implantitis. The majority of studies determine soft tissue scores using a dichotomous system, e.g.: presence or absence of bleeding‐on‐probing (BOP) or suppuration, though some have used an ordinal BOP scale, thus contributing to the range in reported prevalence.

To date, a number of risk indicators have been associated with marginal bone loss. These include patient‐related factors such as smoking, periodontal disease, diabetes, and plaque control/oral hygiene; implant‐related factors such as design of the implant‐abutment complex, and implant shape; as well as surgically related factors including the use of bone grafting, immediate placement, site preparation and loading, the degree of separation between implants, the presence of thin mucosal tissue and soft tissue probing depth. A further understanding of risk indicators associated with bone loss in private practice would aid in mitigating peri‐implantitis.

The objective of this study was to evaluate risk indicators associated with marginal bone loss as observed in private practice, by evaluating changes in crestal bone level over time, from a retrospective cohort study of an initial 4,591 dental implants of various designs1 with a mean of 32.2 months, with some cases up to 5‐ to 10‐years follow‐up. Furthermore, to assess the prevalence of peri‐implantitis, this study aimed to calculate the rate of mucositis and peri‐implantitis using two different thresholds for bleeding on probing from an ordinal scale, while taking care in considering implant design related remodeling and timing of baseline measurements.