A Long-Term Prospective Evaluation of Marginal Bone Level Change Around Different Implant Systems

Purpose: The purpose of this prospective study was to assess the change of marginal bone level around three different types of external-hex implants after 5 years using radiography. Materials and Methods: Included in this study were 54 patients randomly put into three different groups; rough-surface implants (Brånemark), machined coronal aspect implants (Restore), and microthreaded coronal aspect implants (Hexplant). Clinical and radiographic assessments were performed contemporaneously with implant loading (baseline) and at 1, 3, and 5 years post-functional loading. A mixed-model analysis was employed to examine mean marginal bone change significance in the three treatment groups. Results: In a total of 31 out of 54 patients, 81 of 135 implants remained to the end of the study. At 5 years, the microthreaded coronal aspect implants had 0.61 ± 0.32 mm mean crestal bone loss; the rough-surface implants without microthread, 0.99 ± 0.38 mm; and the machined coronal aspect implants, 1.06 ± 0.39 mm. The rough-surface implants and the machined coronal aspect implants did not exhibit statistically significantly different marginal bone loss, whereas the microthreaded coronal aspect implants exhibited significantly less marginal bone loss (P = .0015). Conclusion: In this research, rough-surface implants with microthreads showed positive long-term effects in preserving peri-implant bone level against functional loads when compared with implants lacking these aspects at the coronal part. Most of the bone loss was shown within 1 year of loading, and all types of implants stabilized after 1 year. Keywords: dental implant, marginal bone level, microthread, radiographic evaluation