Soft-tissue dimensional change following guided bone regeneration on peri-implant defects using soft-type block or particulate bone substitutes: 1-year outcomes of a randomized controlled clinical trial

Aim: To compare the peri-implant soft-tissue dimensional changes following guided bone regeneration between particulate (particle group) and collagenated soft-block-type (block group) biphasic calcium phosphate (BCP). Materials and Methods: This study investigated 35 subjects: 18 in the particle group and 17 in the block group. Cone-beam computed tomography obtained at 6 months post surgery and optical impressions taken periodically (before surgery, 6 months post surgery, and 1 year post surgery) were superimposed. The ridge contour changes over time and the peri-implant mucosal thicknesses were measured diagonally and horizontally, and analysed statistically. Results: The increases in diagonal (1.12 ± 0.78 mm) and horizontal (2.79 ± 1.90 mm) ridge contour of the block group were significantly higher than those in the particle group during the first 6 months (p <.05); however, the contour hardly changed thereafter (diagonal: 0.07 ± 0.75 mm; horizontal: −0.34 ± 1.26 mm), resulting in the 1-year contour changes similar between the two groups. Regardless of the type of BCP, the ridge contour increased significantly over 1 year when the dehiscence defect had a contained configuration (p <.05). Conclusions: The increase in soft-tissue dimensions for 1 year was similar between the two groups. The mucosal contour increase was larger when the surgery was conducted in a more contained defect, and this was not influenced by the type of BCP.