Clinical evaluation of tapered-straight-tapered dental implants: a retrospective analysis.

Purpose: This retrospective study aimed to evaluate the long-term survival rate and marginal bone loss (MBL) of tapered-straight-tapered dental implants, considering various associated factors, over an observational period of ≥5 years.

Methods: This study included 186 patients who underwent tapered-straight-tapered dental implant placement at Seoul National University Dental Hospital from 2014 to 2019. Digital panoramic radiographic images and dental records were examined. We evaluated multiple variables, such as sex, age, diabetes mellitus (DM), smoking status, placement region, jaw type (maxilla and mandible), implant diameter, implant length, staged surgery, immediate placement, splinted prosthesis, and implant placement depth (IPD). We first determined the implant survival rate using Kaplan-Meier analysis and analyzed potential risk factors for implant survival using mixed-effects Cox proportional hazards regression. Next, the Mann-Whitney and Kruskal-Wallis tests were used to examine differences in MBL across variables. Linear mixed-effects models with backward stepwise selection were used to identify associations between risk factors and MBL.

Results: This study included 316 implants in 186 patients, monitored over a follow-up period of 7.0±1.36 years. The cumulative survival rate of the implants was 98.1%. The average mesial and distal MBLs were 0.59±1.36 mm and 0.68±1.36 mm, respectively. Linear mixed-effects models indicated that MBL exhibited statistically significant positive correlations with DM (Coeff.=0.614, P=0.026) and staged surgery (Coeff.=0.410, P=0.002). Additionally, greater mesial IPD was associated with reduced MBL (Coeff.=-0.143, P=0.046), and a similar trend was observed for distal IPD (Coeff.=-0.316, P=0.068).

Conclusions: This study demonstrated a high cumulative survival rate for tapered-straight-tapered dental implants over a 5-year period. DM, staged surgery, and IPD showed strong associations with increased MBL. The results suggest that tapered-straight-tapered implants offer advantages in terms of peri-implant MBL and consistent clinical outcomes. These findings underscore the importance of considering these variables in clinical decision-making to optimize implant outcomes.