Titanium dental implants with different collar design and surface modifications: A systematic review on survival rates and marginal bone levels.

Abstract

The aim of this study was to compare clinical and radiographic outcomes of dental implants with different neck characteristics. A protocol-oriented search aimed at the question: "In patients subjected to tooth replacement with screw-type dental implants does the modification of the implant neck macro- or microgeometry contribute to the improvement of survival rates and maintenance of the peri-implant marginal bone levels?" Primary outcomes were survival and marginal bone level (MBL) changes evaluated on randomized controlled trials with >10 participants and follow-up >1year. Risk of bias was evaluated using the Cochrane Collaboration's tool. The review follows the PRISMA statement. Forty-three studies compared: (a) One- versus two-piece implants (N=7); (b) Two-piece implants with different neck characteristics (machined and rough collars, microthreads, LASER microtexturing) (N=21); (c) Two-piece implants with macrogeometry modifications (tapering, back-tapering, and scalloping) (N=6). One- and two-piece implants showed similar survival (RR=0.45, 95% CI: [0.12, 1.66], p=0.23) and MBL changes (WMD=0.09mm, 95% CI: [-0.27, 0.45], p=0.64) at 1-year post-loading. Machined collar implants have higher risk of early failure than rough collar implants (RR=3.96, 95% CI: [1.12, 13.93], p=0.03) and 0.43mm higher bone resorption (95% CI: [0.0, 0.86], p=0.05). Microthreads (WMD=0.07mm, 95% CI: [-0.01, 0.15], p=0.10) and LASER microtexturing (WMD=0.15mm, 95% CI: [-0.35, 0.65], p=0.56) do not reduce bone resorption. Scalloped implants have 1.26mm higher resorption (95% CI: [0.72, 2.00], p<0.001). One- and two-piece implants have similar survival and MBL changes. Rough collar implants have lower MBL changes than machined collar implants. Additional modifications to rough collars are irrelevant.