Comparative analysis of peri-implant marginal bone loss based on micro-thread location: a 1-year prospective study after loading

Abstract

The purpose of the present study was to investigate the effects of micro-thread location on peri-implant marginal bone levels. Two types of implants, one with micro-threads placed at the implant top (Top) and the other with micro-threads placed 0.5 mm below the implant top (Below-top), were placed adjacent to each other in the partially edentulous areas of each of 20 patients. Bone loss around each implant was analyzed after one year of functional loading, and gingival parameters (modified plaque index and modified mucosal index) of the peri-implant soft tissue were evaluated. Bone loss after loading and gingival parameters were compared using the Wilcoxon signed-rank test.The average bone loss in the Top group was 0.16 ± 0.19 mm, and in the Below-top group was 0.30 ± 0.22 mm, after 1-year of functional loading. The Wilcoxon signed-rank test revealed a significant difference in crestal bone loss between the Top and Below-top groups in individual patients (p = 0.002). No significant differences were found between the two groups for the gingival parameters. Less peri-implant bone loss was observed in implants with micro-threads placed at the implant top compared with those in which micro-threads were placed below the top. These results indicate that micro-threads act to stabilize the peri-implant marginal bone and that their location plays an important role in the stabilization process.