Gingival phenotype modification therapies on natural teeth: A network meta‐analysis

BACKGROUND: The periodontal phenotype consists of the bone morphotype, the keratinized tissue (KT), and gingival thickness (GT). The latter two components, overlying the bone, constitute the gingival phenotype. Several techniques have been proposed for enhancing or augmenting KT or GT. However, how phenotype modification therapy (PMT) affects periodontal health and whether the obtained outcomes are maintained over time have not been elucidated. The aim of the present review was to summarize the available evidence in regard to the utilized approaches for gingival PMT and assess their comparative efficacy in augmenting KT, GT and in improving periodontal health using autogenous, allogenic, and xenogeneic grafting approaches. METHODS: A detailed systematic search was performed to identify eligible randomized clinical trials (RCTs) reporting on the changes in GT and KT (primary outcomes). The selected articles were segregated into the type of approach based on having performed a root coverage, or non-root coverage procedure. A network meta-analysis (NMA) was conducted for each approach to assess and compare the outcomes among different treatment arms for the primary outcomes. RESULTS: A total of 105 eligible RCTs were included. 95 pertaining to root coverage (3,539 treated gingival recessions [GRs]), and 10 for non-root coverage procedures (699 total treated sites). The analysis on root coverage procedures showed that all investigated techniques (the acellular dermal matrix [ADM], collagen matrix [CM], connective tissue graft [CTG]) are able to significantly increase the GT, compared with treatment with flap alone. However, KT was only significantly increased with the use of CTG or ADM. Early post-treatment GT was found to inversely predict future GR. For non-root coverage procedures, only the changes in KT could be analyzed; all investigated treatment groups (ADM, CM, free gingival graft [FGG], living cellular construct [LCC], in combination with an apically positioned flap [APF]), resulted in significantly more KT than treatment with APF alone. Additionally, the augmented GT was shown to be sustained, and KT displayed an incremental increase over time. CONCLUSIONS: Within its limitations, it was observed that any graft material was able to significantly enhance GT, while KT in root coverage procedures was significantly enhanced with CTG and ADM, and in non-root coverage procedures, with ADM, CM, FGG, and LCC compared with APF alone. The autogenous soft tissue graft (CTG/FGG) proved to be superior in all comparisons for both outcomes of GT and KT.