Marginal Bone Loss in Relation to Vertical Implant Position

Objectives: Factors associated with proximal implant bone loss are poorly understood. The aim of this study was to determine the association of vertical implant position, relative to interdental bone height (IBH) of adjacent teeth, on marginal bone loss around implants (MIBL).
Methods: Electronic Health Records from 2011 to 2016 were screened for subjects with tooth bound single implants in function. A retrospective radiographic analysis was performed on single TiUnite® surface implants following one year of function. Vertical implant depth was determined relative to the implant platform (IP) and both the IBH and the cemento-enamel junction of each proximal tooth at crown insertion and at least one year after restoration using ImageJ software. The known implant length was used as reference to standardize the radiographic measures. A multi-level logistic regression model was constructed to evaluate the effect of implant position, controlling for other known risk factors, on MIBL. Paired t-test was used to compare the mesial and distal IP depth and MIBL.
Results: 178 subjects with 213 single implants were evaluated with an average of 34.8 months follow-up. The mean distance from IP to the IBH was 1.28±1.04mm and 0.83±1.03mm on the mesial and distal aspects, respectively. The mesial IP was consistently placed deeper than the distal IP, with significantly greater MIBL on the mesial (p<0.01). The deeper the implant position in relation to the IBH, the greater the bone loss on the mesial (r=0.14, p<0.05) and distal (r=0.17, p<0.05) aspects of the implant. History of periodontitis was associated with greater bone loss at the mesial surface of the implant (r=0.17, p<0.05).

Conclusions: Vertical implant position relative to the IBH of adjacent teeth was positively correlated with MIBL of TiUnite® implants. The deeper the implants were placed, the greater marginal bone loss.