The question of how frequently peri-implant disease crops up is not easy to answer. To begin with, there is a lack of specially designed epidemiological studies on the topic. As a result we can only infer the number from retrospective cohort studies. Next, studies define peri-implantitis differently, so results cannot always be compared between studies. Third, the frequency of peri-implantitis in a patient group is subject to diverse factors such as smoking, history of periodontitis etc; therefore, the frequency differs by patient group.
Diverse definitions – varying prevalence
The definition of peri-implantitis, of course, plays a crucial role in calculating the prevalence and incidence. Peri-implantitis is such a recent medical condition that it was rarely treated as a biological complication in studies published prior to 2000.
Meanwhile, in addition to bone loss, probing pocket depth (PPD) is also a relevant clinical parameter, especially when the goal is to diagnose peri-implantitis at an early stage.1 An increasing probing pocket depth is very likely the first indication of the onset of peri-implantitis and suggests the need for a radiographic examination of the state of the bone.
Different studies have defined different probing pocket depth thresholds for diagnosing peri-implantitis (which influences the peri-implantitis prevalence dramatically2). As a rule, a probing pocket depth of 5 mm or more has been taken as a basis for an early indication or stage 1 peri-implantitis, and a probing pocket depth of 6 mm or more for more advanced peri-implantitis (stage 2).
Prevalence subject to patient group
Prof. Giovanni Salvi, Switzerland, has listed the risk factors for peri-implantitis in his blog article. The presence of these risk factors – e.g., smoking, previous periodontitis, hard-to-clean reconstructions and cement residue from implant-supported crowns – also affects the prevalence of peri-implantitis in a patient group.3-7
Systematic review of prevalence
For the third EAO Consensus Conference, a systematic review was undertaken to determine peri-implantitis prevalence and incidence.3 As the studies included in the analysis were heterogeneous, no meta-analysis could be performed, and no unequivocal, exact and relevant proportion of implants could be calculated following a specific peri-implant disease “incubation period.”
The analysis therefore concentrated on describing all the relevant studies, and it was estimated that “five to ten years after implantation, approximately ten percent of the implants and 20 percent of the patients were affected by peri-implantitis.” It needs to be taken into account, however, that this cumulative prevalence of about one percent per year of “incubation” is a very rough estimate subject to the above-mentioned “patient specific” risk factors.