Histological Outcomes of Root Coverage Procedures: A Systematic Review With Meta‐Analysis

Objective To answer the focused PEOS question: In animals or humans with gingival recession defects (P) what are the histological outcomes (O) of different root coverage procedures (RCPs) (E) in preclinical or clinical studies (S)? Methods Electronic databases (MEDLINE, EMBASE, CENTRAL) were searched for eligible studies reporting histological outcomes of RCPs in large‐animal models or humans. Histomorphometric data from animal studies were summarized as pooled means (PM) for each RCP and compared between different RCPs using effect sizes (ES) based on random‐effects meta‐analyses. Results Overall, 41 preclinical (32 canine‐, 5 porcine‐, 4 primate‐models) and 43 clinical studies, mostly case reports/series, were included. The most frequently reported RCPs were coronally advanced flaps with or without connective tissue grafts or soft‐tissue substitutes. Biologicals, such as enamel matrix derivatives (EMD) or membranes, were sometimes used as adjuncts in RCPs. In human biopsies, healing following RCPs mostly occurred via the formation of long junctional epithelium (JE) and connective tissue (CT) adhesion. Some degree of periodontal regeneration was reported in half of the studies. In canine studies with experimentally created defects and limited observation times, PM of new bone, cementum, and CT attachment ranged from 0.17 to 0.50, 0.97 to 2.39, and 1.31 to 2.47, respectively. Meta‐analyses revealed significantly greater new cementum with inserting fibers when using biologicals, particularly EMD (ES 0.86–0.92), or membranes (ES 0.87) as adjuncts in RCPs. Conclusion Healing following RCPs is generally characterized by “repair” (long JE and CT adhesion). Based on animal studies, the adjunctive use of biologicals or membranes in RCPs may enhance periodontal regeneration at least in the short term.