The influence of the distance between narrow implants and the adjacent teeth on marginal bone levels

Objective: To investigate how the distance between narrow implants and adjacent teeth influences the marginal bone levels (MBL) up to 3 years after placement. Material and Methods: A prospective, single-arm, multicenter clinical study was designed to include patients missing 12, 22, 32, 31, 41 or 42 teeth. Implants of 3.0 mm diameter and different lengths were used in the study. One-stage surgery was performed and healing abutments placed during the 6-10 weeks healing period. Clinical and radiographic evaluation was performed at implant installation, loading, and at the 6, 12, 24 and 36-months follow-up visits. Results: Eighty-three implants were placed in 59 patients. A total of 48 implants were placed in narrow implant-to-tooth spaces (percentile 25, 0.83(0.25) mm), 80 in regular spaces (percentile 25 < x < 75, 1.59(0.26) mm) and 47 in wide spaces (percentile 75, 2.61(0.51) mm). Implant MBL change from restoration delivery to 36 months was of 0.50(0.79), 0.50(0.98) and 0.00(0.55) mm in the narrow, regular and wide distance groups (P = 0.005, Mann-Whitney U-test). Changes in MBL on the adjacent teeth were not significant. Conclusion: The distance between narrow-diameter implants and the adjacent teeth does not influence the marginal bone levels neither at the implant or the tooth side. In this study, less marginal bone loss occurred in the narrower spaces.