Monitoring crestal bone level of single- and two-stage implant placement modes up to final prosthetic delivery: an observational study

Objectives: To monitor and compare the nonsubmerged (single-stage, SS) and submerged (two-stage,TS) implant placement techniques up to the final prosthesis delivery. Marginal bone level and marginal bone loss rate of both surgical techniques were compared. Method and materials: Marginal bone level was measured, using an image processing program (ImageJ), from periapical radiographs at the times of placement (TO), exposure (Te), initial loading (T1), and at the final prosthetic delivery (T2), with a total time span of a mean of 13.2 +/- 3.3 months. By timing normalization, marginal bone level and marginal bone loss rate (mm/month), following SS and TS implant placement techniques and other local and systemic parameters were analyzed. Asymmetric analyses using Mann-Whitney test followed by the correlation Pearson analyses were applied. A P value < .05 defined statistical significance. Results: In total, 268 implants (42 patients) were monitored. Marginal bone loss rate was 0.15 +/- 0.13 mm and 0.13 +/- 0.11 mm, between T0 and T2, for the SS and TS techniques, respectively. Marginal bone level and marginal bone loss rate were higher among smokers for both techniques at various time points. Bruxers had higher marginal bone loss rate than nonbruxers between T0 and T1, and T0 and T2. Marginal bone loss rate around implants that were placed at the posterior maxilla was higher than those at the posterior mandible between T1 and T2. Interproximal implant distance correlated negatively with marginal bone loss rate between TO and T2 (P < .05). Conclusions: The results suggest that both techniques achieved similar clinical outcome. Smoking, bruxism, anatomical location, and interproximal implant distance apparently affect the marginal bone level and marginal bone loss rate of both implant placement approaches. The implant placement surgical mode, combined with various systemic and/or anatomical factors could play a significant role in maintaining marginal osseous level around the implant neck.