Randomized controlled clinical trial comparing implant sites augmented with a volume-stable collagen matrix or an autogenous connective tissue graft: 3-year data after insertion of reconstructions

Aim To assess mid-term clinical, radiographic and profilometric outcomes at implant sites, previously grafted with a volume-stable collagen matrix (VCMX) or an autogenous subepithelial connective tissue graft (SCTG). Methods VCMX or SCTG were randomly applied to single implant sites in 20 patients. Following abutment connection and insertion of final reconstructions (baseline), patients were re-examined at 6 months (6M), at 1 year (FU-1) and at 3 years (FU-3). Measurements included the following: clinical data, radiographic measurement of first bone to implant contact (fBIC), soft tissue thickness and volumetric outcomes. Non-parametric tests and estimates were applied for the statistical analysis. Results The median buccal mucosal thickness increased by 0.5 mm (Q1: -0.5; Q3: 1.25) (VCMX) (p = .281) and by 0.8 mm (Q1: 0.0; Q3: 2.5) (SCTG) (p = .047) between BL and FU-3 (intergroup p = .303). The profilometric changes of the buccal soft tissues demonstrated a median decrease between BL and FU-3 of -0.2 mm (Q1: -0.5; Q3: -0.1) (p = .039) for VCMX and a decrease of -0.1 mm (Q1: -0.8; Q3: 0.1) (p = .020) for SCTG, respectively (intergroup p = .596). Peri-implant soft tissues and bone levels remained healthy throughout the entire study period. PROMs did not show any significant differences between the groups nor significant changes over time. Conclusion Minimal changes of the peri-implant tissue contour as well as of the soft tissue thickness were observed at implant sites previously grafted with VCMX or SCTG.