Correlation of Implant Location to Marginal Bone Level Changes in Single-Unit Restorations: A Retrospective Study

The objective of the present study was to determine the emergence angle (EA) values and emergence profiles (EP) for single-unit fixed prosthetic restorations at the bone level, placed in different locations, and to evaluate their effect on radiographic marginal bone loss.

The study included 226 patients (mean age 63.61 ± 14.9 years), and 500 single-unit dental implants were analyzed in three implant localizations: molar, premolar, and anterior. Patient-related factors, implant length and diameter, implant brand, abutment retention type, implant placement time, prosthetic delivery loading type, prosthetic suprastructure type, and duration of prosthetic delivery time-from implant placement to long-term prosthetic functional loading-were recorded. Radiographically, EA, EP, marginal bone level changes (ΔMBL) at mesial and distal aspects were calculated. Receiver operating characteristic (ROC) curve analysis was employed to determine the cut-off point for all implant locations. Binary logistic regression analysis was utilized to identify confounding factors affecting MBL.

The cut-off value of mesial EA was determined for molar, premolar, and anterior regions as 36.422°, 29.703°, and 25.12°, respectively. An increase in the duration of prosthetic delivery time, by every 1 month, the probability of MBL risk was 1.072 times higher. (OR: 1.072; CI: 1.009-1.139; p = 0.025) For the premolar localization variable, the OR value was determined as 2.381, and this indicated that the probability of bone loss in premolar implants is 2.381 times higher than in molar implants. Finally, the OR value of the anterior localization variable was obtained as 3.655, and this value indicated that the probability of bone loss in anterior implants is 3.655 times higher than in molar implants.

The findings of this study indicate that ΔMBL can be evaluated over a range of EA values. It can be stated that as the duration of prosthetic delivery time increases following the surgical placement of dental implants, the risk of marginal bone loss also increases.