title: A cross-sectional study on the prevalence of marginal bone loss among implant patients.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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).
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Institute Franci, Padova, Italy. deniscecchinato@tiscali.it
authors.forename: Denis
authors.initials: D
authors.lastname: Cecchinato
authors.forename: Andrea
authors.initials: A
authors.lastname: Parpaiola
authors.forename: Jan
authors.initials: J
authors.lastname: Lindhe
mesh_terms: D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D015921:Dental Implants; D003774:Dental Plaque Index; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010512:Periodontal Index; D015995:Prevalence; D011859:Radiography; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013548:Sweden / Q000453:epidemiology
chemical_list: D015921:Dental Implants