Marginal bone loss around dental implants with and without microthreads in the neck: A systematic review and meta-analysis

Statement of problem. Whether microthreads in the crestal portion can reduce the amount of marginal bone loss (MBL) around implants has not yet been determined. Purpose. The purpose of this systematic review was to investigate the marginal bone loss around dental implants with and without microthreads in the neck. Material and methods. This review was based on the PRISMA guidelines. An electronic search with no restrictions on language was performed from inception to August 19, 2015, in PubMed, Cochrane Central Register of Controlled Trials, EMBASE, Web of Sciences, and AMED (Ovid) databases. A manual search was also performed. Randomized clinical trials (RCTs) that compared the MBL between implants with and without microthreads in the neck were included. Qualitative synthesis and meta-analysis were performed. MBL was measured by using the mean difference (MD). Review Manager v5.3 software was used for meta-analysis (alpha=.05). Results. Five articles were included in the qualitative synthesis, and 3 articles were included in the meta-analysis. Four studies found that a microthread design can significantly reduce MBL under functional loading, whereas 1 study found no significant difference. The homogeneity test of theta-analysis confirmed acceptable heterogeneity among the 3 studies (I-2=0.49). A random effects model was used. The result shows that MBL around implants with microthread design can be reduced significantly (P=.030; MD: -0.09; CI: -0.18 to -0.01). Conclusions. Meta-analysis showed that microthread design in the implant neck can reduce the amount of MBL; however, RCTs included in the review were few and the difference was small. In clinical practice, an implant with a roughened surface and microthreaded neck could be selected to maintain bone level.