Influence of abutment height on peri-implant marginal bone loss: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Whether abutment height can influence peri-implant marginal bone loss has not yet been determined.

PURPOSE: The purpose of this systematic review and meta-analysis was to investigate the early and late marginal bone loss around implants with long and short abutment height.

MATERIAL AND METHODS: Electronic (PubMed, EMBASE, and Cochrane) and hand literature searches were performed to identify articles published up to May 2018. A random-effects model was used to analyze the weighted mean difference of marginal bone loss between the long and short groups. Potential confounding factors, including implant/abutment connection, healing, and cement- or screw-retained restoration type, were investigated using meta-regression.

RESULTS: Fourteen studies fulfilled the inclusion criteria, and 8 were further included in the meta-analysis. Around bone-level implants with a long abutment, marginal bone loss can be reduced significantly in both the early (-0.52 mm; 95% confidence interval [CI]: -0.79 to -0.24; P=.001) and late (-0.53 mm; 95% CI: -1.03 to -0.02; P=.041) period. Among tissue-level implants, however, and compared with the short-abutment group, more bone loss was found during the early stage in the long abutment (weighted mean difference: 0.28 mm; 95% CI: 0.03 to 0.54; P=.031). Meta-regression failed to find any association between confounding factors and early bone loss around bone-level implants.

CONCLUSIONS: Within the limitation of this systematic review and meta-analysis, abutment height can influence early bone loss around bone-level implants. However, the evidence is insufficient to determine its impact on late bone loss around bone-level implants and early and late bone loss around tissue-level implants.