Limits and drawbacks of classification systems to identify peri-implant diseases. A cross-sectional study with a novel proposal.

Aims Several peri-implant tissue conditions cannot be classified using the standard case definitions of the periimplant diseases. The aim of this study was to estimate the prevalence of mucositis, peri-implantitis, healthy implants and unclassified peri-implant conditions using two principal standard case definitions and to compare their results. Materials and methods Any adult patient with >= 1 dental implant was eligible. Two calibrated operators examined the patients' implants on the basis of pocket depth, bleeding on probing, suppuration and radiographic bone loss. Two different definitions of the peri-implant diseases proposed at the 7th European Workshop on Periodontology (EWPD) and at the 2017 World Workshop (WWD) were compared. Results Fifty-two patients with 92 implants were included. Following the EWPD, 22 implants (24%) were affected by periimplantitis, 60 implants (65%) were affected by mucositis, and 7 implants (8%) were healthy. The remaining 3 implants (3%) cannot be assigned to one definite peri-implant condition. Following the WWD, no implants (0%) were affected by peri-implantitis, 60 implants (65%) were affected by mucositis, and 4 implants (4%) were healthy. The remaining 28 implants (30%) cannot be assigned to one definite periimplant condition. The difference in diagnosis between the two case definitions (EWPD, and WWD) was highly significant (P<0.0001). Conclusions The estimates of the prevalence of the periimplant diseases are different using the two standard case definitions. None of the classifications studied is exhaustive and both have limits and drawbacks. A simple exhaustive modification of EWPD was proposed.