Soft tissue development around abutments with a circular macro-groove in healed sites of partially edentulous posterior maxillae and mandibles: a clinical pilot study

Objectives: The aim of this study was to evaluate soft tissue development at concave circular macro-grooved titanium abutments in healed sites. Material and methods: In a split-mouth pilot study 10 patients received two implants each at healed posterior sites in contralateral maxillary or mandibular jaw quadrants. Either circular macro-grooved concave study abutments or conventional convex control abutments were immediately provisionalized and received permanent crowns 3 months postimplantation. Marginal bone level, papilla index, modified plaque and bleeding index were recorded. The esthetic outcome was evaluated with standardized perpendicular pictures according to the Pink Esthetic Score (PES). Statistical analysis included the description of all variables by mean value, standard deviation and range. PES values were compared using the Wilcoxon signed rank test for paired data. Results: Cumulative survival rate for all 20 implants was 100%. At the 1-year follow up, there was no statistical significant difference of marginal bone levels between sites restored with the study (-0.11 +/- 0.77 mm) vs. the control (-0.34 +/- 0.53 mm) abutments (P>0.05). Esthetic evaluation (PES) revealed statistically significant differences in scores between the study group [study abutment group] (7.2 +/- 2.82, 8 +/- 1.89) and the control group [control abutment group] (9.5 +/- 1.58, 10.5 +/- 1.72) at the time of prosthetic delivery and the 1-year follow-up. Whereas PES scores for mesial papilla at control sites at the 1-year follow-up demonstrated statistically significant higher values, both soft tissue level and soft tissue contour at control sites revealed statistically significantly higher PES values (P<0.05) at time of prosthetic delivery and at 1-year follow-up when compared with study sites. Conclusions: Concave macro-grooved abutments in healed posterior maxillary and mandibular sites did not exhibit a superior soft tissue development compared with standard convex abutments.