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Table 2 Summary of risk of bias of included studies

From: A systematic review and meta-analysis of the role of sugar-free chewing gum on Streptococcus mutans

  Study design Randomisation Allocation concealment Masking of participants Masking of outcome assessors Incomplete outcome reporting Selective reporting Other bias
Hoerman [16] RCT Unclear High risk unclear Unclear Low risk Low risk Low risk
Hildebrandt and Sparks [17] RCT Unclear Unclear Unclear Low risk Unclear Unclear Unclear
Thaweboon et al. [18] Other Unclear [1] Unclear Unclear Unclear Unclear Unclear Unclear
Makinen et al. [19] RCT Unclear Unclear Low risk Low risk High risk Unclear Unclear
Wang et al. [20] RCT Low risk Unclear Unclear Unclear Low risk Unclear Unclear
Haresaku et al. [20] Patient preference non-randomised trial High risk [2] Unclear Unclear Low risk High risk Unclear Unclear
Calgar et al. [22] RCT Low risk Unclear Low risk Low risk Unclear Unclear Low risk
Campus et al. [23] RCT Low risk Low risk Low risk Low risk Unclear Unclear Low risk
Hildebrandt et al. [24] RCT Low risk Unclear High risk Low risk Low risk Unclear Unclear
Seki et al. [25] RCT Low risk Low risk Low risk Unclear High risk Unclear High risk
Alamoudi et al. [26]
Hanno et al. [27]
RCT Unclear High risk High risk Unclear Unclear Unclear Unclear
Al-haboubi et al. [28] RCT Low risk Low risk High risk Low risk Unclear Unclear Low risk
Ghassemi et al. [29] RCT Unclear Unclear Low risk Unclear Low risk Unclear Unclear
  1. Participants were divided into three groups which were balanced according to their S. mutans counts at baseline: one control group (no supervised gum use), and two xylitol groups (supervised 55% and 100% xylitol gum use). It is unclear whether they were or not randomised after stratification
  2. Participants’ preference for the flavour of gum was taken into account at allocation in an effort to enhance adherence to the chewing regimen