Adjunctive effect of soft tissue grafting in the surgical treatment of peri-implantitis: clinical and radiographic outcomes from a preclinical canine experiment

Abstract

Purpose: The aim of this study was to clinically and radiographically investigate the effect of soft tissue grafting as an adjunct in the surgical treatment of ligature-induced peri-implantitis lesions in canines. Methods: Seven Mongrel dogs received implant placements on both sides of the posterior mandible (3 fixtures per side). After inducing peri-implantitis via ligation with suture material, surgical treatment was performed on each implant according to randomly assigned groups: DI, implantoplasty only; DIB, implantoplasty followed by collagenated, deproteinized bovine bone mineral (DBBM-C) grafting; DIC, implantoplasty followed by autogenous connective tissue graft (CTG); DIV, implantoplasty followed by volume-stable collagen matrix (VCMX) grafting; DIBC, implantoplasty followed by DBBM-C grafting and CTG; and DIBV, implantoplasty followed by DBBM-C and VCMX grafting. Clinical and radiographic outcomes were evaluated. Composite treatment success was defined by the following criteria: absence of bleeding on probing at 12 weeks post-surgery; a reduction in probing depth (PD) or an increase of 1 mm or less in PD at 12 weeks post-surgery; and absence of additional bone loss >= 0.5 mm at 12 weeks post-surgery compared to radiographic baseline. Statistical significance was set at P<0.05. Results: All groups exhibited clinical and radiographic improvement after surgery. Clinical parameters, radiographic bone levels, and mucosal thickness did not significantly differ among the groups. The DI and DIV groups demonstrated higher composite treatment success rates (71.4%) compared to the other 4 groups. Adjunctive soft tissue grafting resulted in fewer changes in peri-implant mucosa. The effect of hard tissue grafting on bone regeneration was minimal, and combining hard and soft tissue grafting did not yield better outcomes than implantoplasty alone. Conclusions: The surgical treatment of peri-implantit is lesions remains challenging. Soft tissue grafting showed clinical benefits by reducing changes in the peri-implant mucosa. The effect of hard tissue grafting on bone regeneration was very limited.