The aim of the present cross-sectional retrospective study was to determine bone loss in a sample of subjects restored with implant-supported prostheses and the prevalence and severity of peri-implantitis in a sub-sample.
A total of 139 patients who had attended a follow-up visit in 2007 were considered for inclusion. Subjects with implants that had been in function for less than 3?years or had poor quality radiographs were excluded. The final study population comprised 133 subjects with a total of 407 implants. Radiographic measurements identified subjects who had =1 implant site exhibiting marginal bone loss of >0.5?mm; 40 subjects met this criterion and were recalled for a clinical examination. Of the 40 subjects that were recalled for the clinical examination, 30 attended. The following parameters were recorded at mesial, distal, buccal, and lingual/palatal aspects of all implants: oral hygiene standard (plaque), bleeding on probing, probing pocket depth (PPD).
The mean interval between the baseline (1-year post-loading) and the follow-up radiographs was 4.8???2.3?years. In the total subject sample (133 subjects and 407 implants), the mean amount of marginal bone loss that had occurred was 0.2???1.2?mm. Ninety-three subjects with 246 implant sites exhibited no bone level alteration (group A), whereas 40 subjects with 161 implant sites (group B) displayed marginal bone loss of >0.5?mm at =1 implant (loser site). Sixty-eight implant sites in group B exhibited bone loss of >0.5?mm. However, only 20% of subjects and 11% of sites had lost >1?mm marginal bone, and 8% of subjects and 4% of sites had lost >2?mm bone. The total amount of bone loss that had occurred in group B was (i) 0.88???1.5?mm and (ii) among the loser sites 2.1???1.4?mm. Thirty subjects from group B were exposed to a clinical examination; out of 37 sites with bone loss >0.5?mm in this subgroup, 29 sites had a PPD value of =4?mm.
Marginal bone loss (>0.5?mm) at implants was observed in 30% of subjects and 16% of implant sites. More advanced loss of marginal bone occurred in much fewer subjects and sites. Sites with marginal bone loss was in the sub-sample characterized by bleeding on probing, but only occasionally with deep (=6?mm) pockets.