Is the clinical performance of dental implants influenced by different macrogeometries? A systematic review and meta-analysis.

Statement of problem: Although tapered and cylindrical implants have been widely used, a consensus on which macrogeometry offers better clinical performance is lacking.

Purpose: The purpose of this systematic review and meta-analysis was to evaluate the influence of different macrogeometries (tapered and cylindrical) on the clinical performance of dental implants.

Material and methods: The study was registered in the international prospective register of systematic reviews (PROSPERO) database (CRD42022347436). A search for clinical studies was conducted in 6 databases to identify randomized controlled clinical trials that evaluated the effectiveness of tapered and cylindrical implants placed in the maxilla or mandible of adult patients that had at least 1 clinical performance parameter as outcome. The risk of bias was evaluated using the revised Cochrane Risk-of-Bias Tool (RoB 2) tool. Meta-analyses on implant survival and success, marginal bone loss (MBL), implant stability (ISQ), and torque insertion (TI) were performed, with the certainty of evidence evaluated using the grading of recommendations, assessment, development, and evaluations (GRADE) checklist.

Results: Of the 18 included studies, 7 had a low risk, 6 had some concerns, and 5 had a high risk of bias. Meta-analyses of survival (RR 0.99 [0.97, 1.01]; P=.38; I2=0%), implant success (RR 1.06 [0.99, 1.13] P=.08 I2=0%), 1-month MBL (MD -0.11 [-0.33, 0.10] P=.31 I2=98%), 3 months MBL (MD -0.21 [-0.27, 0.16] P=.26 I2=98%), 6 months MBL (MD -0.29 [-0.60, 0.01] P=.06 I²=74%), 1-year MBL (MD 0.01 [-0.07, 0.09] P=.77 I2=98%) and after 2 years MBL (MD -0.04 [-0.14, 0.07] P=.52 I2=0%), ISQ at implant installation (MD 0.35 [-0.72, 1.42] P=.52 I2=0%), %), after 2 months (MD 0.90 [-1.08, 2.87] P=.37 I2=0%) and at 1 year (MD -0.02 [-1.07, 1.03] P=.97 I2=0%), and insertion torque (MD 3.10 [-1.71, 7.92] P=.21 I2=80%) were statistically similar. However, tapered implants showed higher ISQ than cylindrical implants after 3 months (MD 1.20 [0.39, 2.01] P=.004 I2=17%). The certainty of evidence for the analyzed parameters ranged from high to very low.

Conclusions: Both macrogeometries present good clinical performance, with certainty of evidence ranging from high to very low. Tapered implants showed better secondary stability at 3 months after implant installation, but with low certainty of evidence.