Objective: The aim of this systematic review (SR) was to evaluate the effects of xenogenic collagen matrix (XCM) on the outcomes of clinical treatments of patients with Miller class-I or -II gingival recessions. Materials and methods: Articles that were published before March 2018 were electronically searched in four databases without any date or language restrictions and manually searched in regular journals and gray literature. The eligibility criteria comprised randomized controlled trials (RCTs) and prospective controlled trials with follow-up periods of 6 months or more that compared the performance of XCM in the treatment of Miller class-I or -II gingival recessions. This SR was registered in PROSPERO under number CRD42018106118. Results: Nine RCTs published between 2010 and 2018 were included in this SR. The percentage of root coverage (RC) was significantly higher (p = .0003) when gingival recessions were treated with XCM when compared to coronally advanced flap (CAF) alone. In addition, the parameters of keratinized mucosa width (KMW) (p = .006) and gingival thickness (GT) (p = .0003) were also improved when the XCM was used in comparison to the CAF alone. There was not a statistically significant difference (p = .22) between the clinical attachment level (CAL) achieved with the use of XCM and that achieved with CAF alone. RC with the use of XCM, when compared to connective tissue grafts (CTGs) (p = .09) and enamel matrix derivative (EMD) (p = .62), there was no significant difference; however, XCM yielded lower RC than CTG in the treatment of Miller class-I or -II gingival recessions. Conclusions: Based on both the individual studies' outcomes and the pooled estimates, it can be concluded that the use of XCM improves the RC, KMW and GT in the treatment of gingival recessions when compared to CAF alone and may be a viable alternative to use of CTG.
Keywords: Gingival recession; graft; periodontal plastic surgery; xenogenic collagen matrix.