The effect of marginal bone level changes on the stability of dental implants in a short-term evaluation.

Abstract

To evaluate whether changes in marginal bone level (MBL) around implants, in sites with different bone types, affect the over time implant stability measured by resonance frequency analysis (RFA). Seventy-eight implants were inserted into jawbones of 32 patients using a two-stage surgical protocol, and implant bone sites were grouped according to the Lekholm and Zarb bone classification. The implant stability quotient (ISQ) was measured by RFA at four time points: implant placement, uncovering, rehabilitation, and at 1-year follow-up after loading. The MBL was measured on periapical radiographs at uncovering and at 1-year follow-up. Percent change in bone level was calculated based on the difference between the implant length and height from the crestal bone level to the implant apex. Descriptive statistics, Pearson's correlation, and repeated-measures ANOVA were used for data analysis. Significant improvement of ISQ was found between implant insertion and uncovering surgery (P<0.001), while no significant changes were detected throughout the remaining follow-up period. The greatest improvement of ISQ was observed for bone type 4, compared with the other groups (P<0.001). Percent change in bone level had no effect on longitudinal measures of ISQ (P=0.337). The ISQ difference between uncovering and 1year after loading was not correlated with percent change in bone level (r=0.16; P=0.157). There was increased implant stability after implant placement, but it was not affected by changes in marginal bone level during the first year of loading.