Predictive factors for insertion torque values in transalveolar sinus lift procedures.

Objectives: The objective of this retrospective study was to investigate the impact of bone-related factors such as initial bone height (IBH), imaginary pixel unit (IPU), bone diameter (BD), crestal cortical thickness (CCT), and sinus floor thickness (SFT) in transalveolar sinus lift procedures using threaded bone expanders without bone graft materials.

Materials And Methods: This retrospective cohort study was carried out on patients who had reported to the department of oral and maxillofacial surgery at Tishreen University between January 2018 and June 2024. The sample consisted of patients who had transalveolar sinus lift using motorized threaded bone expanders with simultaneous hybrid dental implants placement without bone graft materials. The bone-related factors, including initial bone height (IBH), imaginary pixel unit (IPU), bone diameter (BD), crestal cortical thickness (CCT), and sinus floor thickness (SFT) were analyzed using CBCT scans that were taken preoperatively. Statistical analysis was performed to assess the relationship of the factors and insertion torque of the dental implant. The statistical analysis includes descriptive statistics for all variables mentioned. A Uni-variate linear regression (Spearman's correlation) and multivariate linear regression were performed to assess the relation between Insertion torque and the explanatory variables. The p values < 0.05 were considered to be statistically significant. The Newey West correction for heteroskedasticity was applied.

Results: In this retrospective study, 124 hybrid implants (cylindrical in coronal section and conical in apical section) were placed in 113 patients (53 males and 60 females) in the posterior region of the maxilla in conjunction with transalveolar sinus lift. In the Uni-variate analysis, we observed a strong positive correlation between IT and IPU, a weak positive correlation between IT and SFT, and between IT and CCT. There was no correlation found between IT and IBH, as well as between IT and BD. Through multivariate analysis, we found that IPU and CCT were associated with higher values of IT, whereas IBH, BD, and SFT were not significantly associated with the value of insertion torque.

Conclusions: Our study indicates that, within its limitations, insertion torque values in transalveolar sinus lift procedures using threaded bone expanders and hybrid implants are primarily influenced by cortical bone thickness and imaginary pixel unit, while factors such as sinus floor thickness, initial bone height, and bone diameter do not significantly affect these values.