Healing of a xenogeneic collagen matrix for keratinized tissue augmentation

Aim To evaluate histologically the healing of a xenogeneic collagen matrix (CM) used to augment the width of keratinized tissue around teeth. Materials and methods The gingiva on the buccal aspect of mandibular and maxillary premolars was surgically excised on 12 minipigs. After 1 month of plaque accumulation, the resulting defects were randomly treated by a periosteal retention procedure (control site) or by placing a collagen matrix after an apically repositioned flap (CM) (test site). Clinical and histological outcomes were evaluated at 1, 4 and at 12 weeks. Results Clinically, no gain of keratinized tissue was noted in either group. Histometrically, the thickness of the gingival unit was significantly higher in the test group at 1 month, although these differences were not significant at 3 months. There was a tendency in the test group towards less bone resorption (0.7 mm) and apical displacement (0.5 mm) of the gingival margin at 3 months. Conclusions The tested CM demonstrated uneventful healing, being resorbed within the surrounding tissues in absence of significant inflammation. When compared with periosteal retention alone, the CM group attained similar clinical and histological outcomes.