Xenogeneic collagen matrix versus free gingival graft for augmenting keratinized mucosa around posterior mandibular implants: a randomized clinical trial.

Abstract

To assess the clinical efficacy of xenogeneic collagen matrix (XCM) plus apically positioned flap (APF) in augmenting the keratinized mucosa (KM) width (KMW) and thickness (KMT) around posterior mandibular implants and compare it with free gingival graft (FGG) plus APF. Thirty patients with KMW ≤ 2mm in the posterior mandibular implant site were randomly allocated to the FGG group (FGG plus APF) or the XCM group (XCM plus APF). Clinical assessments, including KMW and KMT, shrinkage rate of established KM, and peri-implant soft tissue health, were evaluated during a 6-month follow-up. Additionally, the esthetic outcomes and patient-reported postoperative morbidity were investigated. At 6months, the KMW measured 3.60 ± 0.79mm in the FGG group and 3.28 ± 0.96mm in the XCM group (p = 0.186). Both groups showed a tendency for graft contraction (FGG, 42.11%; XCM, 53.22%). The KMT measured 1.24 ± 0.34mm in the FGG group and 0.95 ± 0.29mm in the XCM group, with statistical difference (p = 0.002). No difference in the peri-implant soft tissue health was observed between the two groups (p > 0.05), but the esthetic outcomes were better in the XCM group (p < 0.05). XCM plus APF rendered a similar clinical efficacy in augmenting KMW as that with FGG plus APF, but with higher shrinkage. XCM plus APF was inferior with respect to FGG plus APF in augmenting KMT. The esthetic outcomes were better with XCM plus APF than FGG plus APF. Clinical relevance XCM plus APF graft was inferior with respect to FGG plus APF in augmenting KMT. Trial registration number: ChiCTR2200058027 and date: 03/27/2022.