Histomorphometry and Immunohistochemistry of Xenogeneic Collagen Matrix: A Randomized Split‐Mouth Clinical Study

Objectives

To histomorphometrically evaluate collagen formation and immunohistochemically assess soft tissue vascularization around implants after treatment with xenogeneic acellular collagen matrix versus connective tissue graft in a randomized split‐mouth clinical study.

Materials and Methods

Nine patients underwent implant rehabilitation with connective tissue graft and xenogeneic acellular collagen matrix in contralateral edentulous areas. A total of 24 grafts were performed (12 each). Grafts were assigned to healing times of 30 ( n  = 4), 90 ( n  = 4), or 180 days ( n  = 4), at which time samples were collected for histological and immunohistochemical analysis. Collagen quality and density were assessed histologically. Vascularization, vessel density, and diameter were evaluated immunohistochemically. Samples were stained with Masson's trichrome for collagen and immunostained with CD34 for vascular endothelium; the grafted site was the unit of analysis.

Results

The percentage of collagen was higher in sites biopsied at 180 days for both grafts and was similar between groups at all healing periods. Xenogeneic acellular collagen matrix showed vascularization patterns similar to autogenous connective tissue graft, with higher vessel density and vascular percentage at 90 days, while differences between groups were observed only at 30 days.

Conclusions

Within the limitations of this study, xenogeneic acellular collagen matrix demonstrated collagen maturation at the later healing periods and vascularization patterns with histological characteristics similar to those of the connective tissue graft during the evaluated healing periods.

Trial Registration: Brazilian Registry of Clinical Trials (ReBEC), RBR‐4vgzyt.