Gingival phenotype modification using collagen matrix versus acellular allogenic dermal matrix: A comparative preclinical study

Soft-tissue substitutes are increasingly used to avoid donor-site morbidity associated with autogenous grafting, yet direct preclinical comparisons of acellular allogenic dermal matrix (ADM) and collagen matrix (CM) remain scarce. This study investigated the early healing and remodeling profiles of ADM and CM in a canine split-mouth model. Eight male mongrel dogs (16 labial sites at the maxillary second incisors) received randomized subperiosteal tunnel grafting with ADM or CM and were euthanized at 4 or 8 weeks (n = 4 per time point). Gingival thickness and volume were quantified by 3D intraoral scans. At sacrifice, histometric thickness, rete peg counts, hematoxylin and eosin interface morphology, and immunohistochemical expression of type I collagen (Col I) and vascular endothelial growth factor (VEGF) were evaluated. Both materials produced immediate soft-tissue gains followed by partial contraction during healing while remaining above baseline. At 4 and 8 weeks, no detectable between-material differences were observed in histometric and 3D outcomes, rete peg counts, or VEGF expression. Histology showed close graft-host apposition at 4 weeks and a denser, collagen-rich interface at 8 weeks. Col I expression increased in both groups. These findings suggest similar early healing and connective tissue remodeling patterns within the limitations of this short-term canine model.