Study	Reason for exclusion
Daudt 2013	Inappropriate statistical analysis (randomisation and analysis at tooth level without accounting for the clustering effect of teeth within individual participants)
Fontes 2009	Inappropriate study design. The study authors kindly provided us with a prepublication copy of the study and we were able to see that the study claimed to be performed using a split‐mouth design, but not carried out it in an appropriate way
Ganss 1999	Randomisation allocation not performed between the rubber dam and cotton rolls isolation groups
Huth 2004	Study was a CCT as randomisation allocation was not performed between the 2 treatment groups, and using teeth as the analysis unit
Raskin 2000	Inappropriate statistical analysis (randomisation and analysis at tooth level without accounting for the clustering effect of teeth within individual participants)
Sabbagh 2011	Conference abstract without mentioning randomisation allocation between the 2 treatment groups, and author contact failed
Smales 1993	Study was a CCT as randomisation allocation was not performed between the 2 treatment groups, and using teeth as the analysis unit
Straffon 1985	Randomisation allocation not performed between the rubber dam and cotton roll isolation groups and using tooth surfaces as the analysis unit
van Dijken 1987	Study was a CCT as randomisation allocation was not performed between the 2 treatment groups

CCT: controlled clinical trial.