Marginal bone loss at implants with different surface characteristics - A 20-year follow-up of a randomized controlled clinical trial. 
This report is a 20-year follow-up of a randomized controlled clinical trial evaluating the potential long-term effect of a modified implant surface on the preservation of the peri-implant marginal bone level.  In each of 51 patients and for each fixed partial denture (FPD), by randomization at least one implant installed had a non-modified turned surface and one a modified and roughened surface (TiOblast® ).  Clinical and radiological examinations were performed at various follow-up intervals.  Primary outcome variables were peri-implant marginal bone level change from time of loading and proportion of implants with no bone loss at 20 years.  Multilevel analysis followed by nonparametric and Pearson's Chi-Square tests were applied for statistical analysis.  At the 20-year follow-up, 25 patients carrying 64 implants were available for evaluation.  Turned and TiOblast implants presented with a mean bone level change from the time of FDP delivery amounting to -0.41 mm (95% CI -0.84/0.02) and -0.83 mm (95% CI -1.38/-0.28) respectively (inter-group comparison p > .05).  47% of the Turned and 34% TiOblast implants (p > .05) showed no bone loss.  All but one of these implants were free of bacterial plaque and inflammation as well as presented with probing pocket depths ≤5 mm at both the 5- and 20-year follow-up examinations.  It is suggested that a moderate increase of implant surface roughness has no beneficial effect on long-term preservation of the peri-implant marginal bone level.