Table 3 Risk-of-bias assessment for the studies included in the meta-analysis (NOS)

(nRCT) Study = 6

Item 1

Item 2

Item 3

Item 4

Item 5A

Item 5B

Item 6

Item 7

Item 8

Score

 Goldstein WM et al. (2001) [23]

*

*

*

*

*

*

*

7

 Tsai SJ et al. (2008) [24]

*

*

*

*

*

*

*

*

8

 White Jr. RE (2001) [25]

*

*

*

*

*

*

*

*

8

 Pellicci PM et al. (1998) [27]

*

*

*

*

*

*

*

7

 Suh KT et al (2004) [28]

*

*

*

*

*

*

*

*

*

8

 Yamaguchi T et al. (2003) [21]

*

*

*

*

*

*

*

*

8

RCT Study = 2

Random Sequence Generation

Allocation Concealment

Blinding of Participants and Personnel

Incomplete Outcome Data

SelectiveReporting

Overall Bias

 Chiu FY et al. (2000) [22]

Low

Low

Unclear

Low

Low

Low

 Tarasevicius S et al. (2010) [29]

Low

Low

Low

High

High

High