Marginal Bone Level Changes at Dental Implants after 5 Years in Function: A Meta-Analysis

Abstract

It is important that peri-implant bone breakdown caused by, for example, undue load and/or peri-implantitis, is prevented or minimized. Some continuous loss of marginal bone is generally accepted, but the question remains as to what extent it must occur. The purpose of this study was to compile and compare data on peri-implant marginal bone level changes from prospective studies that have registered the peri-implant marginal bone level radiographically at the time of prosthetic loading, and after 5 years of follow-up for implant systems currently available on the market. A literature search was carried out to identify prospective studies on peri-implant marginal bone level changes around dental implants. To be included in a meta-analysis, the implant systems should have been subjected to at least two independent studies. Copycats without documentation were not accepted. Forty prospective studies that presented with a 5-year data were identified. Three implant systems met the inclusion criteria of having at least two independent studies; Astra Tech Dental Implant System® (Astra Tech AB, Mölndal, Sweden), Brånemark System (Nobel Biocare AB, Göteborg, Sweden), and Straumann Dental Implant System (Institute Straumann AG, Basel, Switzerland). The pooled mean marginal bone level change amounted to -0.24 mm (95% CI -0.345, -0.135) for the Astra Tech Dental Implant System, 0.75 mm (95% CI -0.802, -0.693) for the Brånemark System, and 0.48 mm (95% CI -0.598, -0.360) for the Straumann Dental Implant System over 5 years, with a statistically significant difference (p < .01) between the systems. The identified implant systems showed an annual bone loss below or much below what hitherto has been set up as a limit for success. A careful documentation of marginal bone level changes should be mandatory for all implant systems before being marketed. It is also time for revision of existing success criteria to refine the basis for clinical quality judgment of implant treatment.