Evaluation of the Safety and Efficacy of Soft Tissue Augmentation With a Compressive-Resistant Collagen Matrix in a Nonhuman Primate Model

The purpose of the present study was to evaluate the safety and efficacy of the compression-resistant collagen-based cross-linked matrix for augmentation of maxillary and mandibular soft tissue defects in an animal model. Six rhesus macaque monkeys were subjected to soft tissue grafting in 4 sites intraorally; the anterior maxilla was subjected to hard and soft tissue grafting with implant placement. Each site was randomly assigned 1 of 3 treatments: a compressive-resistant collagen matrix membrane (CM), a subepithelial connective tissue autograft (SCTG), or sham treatment, in which a partial-thickness flap was elevated and then sutured closed with no further treatment (control). The following methods were used for data collection: in vivo evaluation by periodontal probing, ultrasound, shear modulus elasticity, polyether impressions for volumetric analysis, and in vitro analysis by histologic biopsy examinations. In vitro analysis provided by histologic measurements and evaluations was performed on nondecalcified sections. The follow-up period was 6 months. The SCTG and CM showed favorable tissue integration. No adverse reaction to or deviation from the normal healing processes was detected. The CM integrated well in all sites, with a variable range of soft tissue volume increases. Volumetric discrepancies were appreciated in the histologic analyses and differences were found when the CM and SCTG were applied in the anterior maxilla in combination with hard tissue grafting and implant placement. Histologic evaluation showed favorable integration, no immunogenic response to the CM, and stable volumetric retention in autograft and CM sites during the experimental period. The compressive-resistant CM could be a safe and efficacious alternative for soft tissue augmentation by obviating a donor site and the consequent morbidity. Although a similar performance between the CM and SCTG was observed, further studies will be necessary to estimate the clinical potentiality and describe the limits of the technique.