Comparison of clinical outcomes, histomorphometric and gene expression analysis of connective tissue graft with two types of xenogeneic matrices for peri-implant vertical soft tissue augmentation

Peri-implant soft tissues are key to maintaining peri-implant health. An adequate soft tissue seal prevents microbial ingress, provides aesthetic results and harmonious integration of the prosthesis with the remaining dentition. The connective tissue graft (CTG) harvested from the palate is the gold standard for soft tissue augmentation. However, it is associated with a need for a second surgical site, increased patient morbidity, longer surgical duration and a possibility of postsurgical complications. To address these challenges, several new biomaterials have been developed. These include newly developed porcine acellular dermal matrix (PADM) and volume stable collagen matrix (VCMX). However, it remains unclear whether they can achieve similar clinical outcomes as CTG in terms of vertical soft tissue thickness gain following submerged implant placement. The present study is aimed at comparing the clinical performance of PADM, VCMX and CTG for vertical soft tissue augmentation at implant sites presenting with baseline soft tissue thickness ≤ 2 mm. Further, histologic and histomorphometric assessment would be carried out to evaluate the inflammatory response, collagen content and micro-vessel density in the grafted tissue after 3 months of healing. Also, there is lack of data on the gene expression of biological importance during healing at molecular level in the grafted sites. Therefore, we will also characterize acute changes in gene expression by performing RNAseq analysis of the biopsied soft tissue to identify cellular pathways that become altered upon successful grafting in VCMX or PADM groups compared to CTG control.