Degree of Risk of Bias in Randomized Controlled Trials: Does it Have an Impact on Root Coverage Outcomes?

ABSTRACT Background Improvement over time in mean (MRC) and complete root coverage (CRC) reported in randomized controlled trials (RCTs) has been documented. In addition to technical factors, this positive trend could also be influenced by changes in the degree of risk of bias (ROB) in these trials. Methods RCTs that involved the use of a bilaminar technique of coronally advanced flap with connective tissue graft (CAF+CTG) were selected. The following data was extracted: MRC, CRC, whether conflict of interest was addressed (yes/no), adequacy of random sequence generation, allocation concealment and blinding of outcome assessment. Trials were categorized into four groups according to different time periods: pre-CONSORT (before 1996), CONSORT (1997 to 2001), CONSORT 2001 (2002 to 2010) and CONSORT 2010 (2011 to 2019). Differences between group means were assessed using statistical analyses. Results The search yielded a total of 47 RCTs published between 1993 and 2019 that met the inclusion criteria. A trend towards lower ROB over time in the selected RCTs was observed. However, differences in MRC and CRC with respect to the degree ROB of included trials were not significant. Conclusions Degree of ROB did not influence MRC and CRC reported in the RCTs included in this investigation. This finding suggests that the observed improvement of clinical outcomes over time should be attributed to other factors, such as refinement of surgical techniques.