Evidence-based mucogingival therapy. Part 2: Ordinary and individual patient data meta-analyses of surgical treatment of recession using complete root coverage as the outcome variable

Background: The literature (1970-2000) on the outcome of surgical root coverage has been revised and summarized in a companion paper. The overall conclusion was that the various procedures are effective, but it was not possible to determine which procedure was best indicated in different clinical conditions. In this study, meta-analysis techniques were used to seek evidence for guiding clinical decisions when planning root coverage surgery. The aim of this study was to illustrate the differences between meta-analyses applied to summarized and individual patient data (IPD) and to present suggestions for reducing the costs of IPD meta-analysis. Methods: Only clinical trials and case series that included data on the number of teeth treated, baseline recession depth (BRD) and the proportions of postoperative complete root coverage (CRC) were considered. The first group of meta-analyses (the outcome of each procedure based on summarized data) covered 65 studies dealing with coronally advanced flap (CAF), epithelial free gingival graft (EFGG), connective tissue graft (CTG), and guided tissue regeneration (GTR) procedures. The second group of meta-analyses was done to determine the outcome of each procedure on the basis of 26 studies that reported IPD for at least baseline recession depth (BRD) and final CRC for each site. The third group of meta-analysis compared the outcomes of CTG and GTR in 5 randomized studies, 4 of which reported only summarized data. Results: The first analysis showed that CRC was achieved more often in non-randomized than in randomized studies. The heterogeneity tests revealed great variability of results in both the randomized and non-randomized studies, which makes it difficult to draw any definite conclusions. In the second analysis all the tested techniques revealed similar trends: greater baseline recession depths were always associated with a decreased CRC. The third analysis showed that CRC was achieved more frequently in the sites treated with CTG as opposed to GTR. The small sample size and the lack of IPD rendered the analyses inconclusive despite the randomized design. Conclusions: Few studies reported individual patient data; they are a valuable contribution to clinical decision making, but IPD published in the literature are still insufficient to provide a reliable guide for clinical decision making. Therefore, decisive steps should be taken to facilitate the publication of IPD, in electronic format, whenever a clinical study is published in a leading journal.