Radiographic comparison of crestal bone resorption around two implant systems; a retrospective study

Bone resorption is one of the most common problems reported in the bones around the implant. Several factors are involved in this bone resorption, one of which is the microstructure and macrostructure properties of the implant. In the present study, the effect of microstructure and macrostructure of implants on crestal bone resorption was evaluated. This descriptive study was performed on the records of 115 patients with 181 implants between 2011 to 2020 in faculty of dentistry of Shahed University. Patients with two types of implants (ITI and DIO) were evaluated. Parallel peri apical radiographs were taken immediately after implant placement, at prosthesis delivery, as well as annual follow-ups. Digital radiographs were taken by Scanora software and the length of the crestal bone was calculated. To investigate the process of bone resorption over time in all types of implants and according to the type of crown, marginal models were used by GEE (Generalized Estimating Equations) estimation method with the identity correlation function and the unstructured correlation structure. The reliability coefficients of the variables were greater than 0.9. 139 implants were bone level, and 42 implants were tissue level. Bone resorption was significant over time (P<0.001). In addition, the interaction between time and type of implant was significant (P=0.015). The pattern of resorption was higher over time in ITI (tissue level) than ITI (bone level) and DIO (bone-level) implants (P<0.001). The bone resorption around the implant is clinically acceptable for both ITI and DIO groups over a two-year period. Bone resorption was lower in the DIO group than in the ITI. However, this difference was related to the ITI-tissue level implants.