Table.

Characteristics of Included Articles

Characteristics of RCTs	Number of RCTs (%) n = 317
Trial registration
Required or recommended	150 (47%)
Referred indirectly	82 (26%)
Not referred	85 (27%)
Design
Parallel-arm	217 (68%)*
Split-mouth	65 (21%)*
Crossover	37 (17%)
Cluster	7 (2%)
Ethics committee reported	270 (85%)
Risk of selection bias
Low risk	61 (19%)
High risk	3 (1%)
Unclear	253 (80%)
Trial registration	73 (23%)
Trial register number reported in the published article	50
Trial register number not reported in the published article	23
ClinicalTrials.gov	52 (71%)
ISRCTN	10 (14%)
Australian New Zealand Clinical Trials Registry	4 (5%)
European Community Clinical Trial System	2 (3%)
Iranian Registry of Clinical Trials	2 (3%)
German Clinical Trials Register	2 (3%)
Dutch Trial Registration	1 (1%)

RCT, randomized controlled trial; ISRCTN: International Standard Randomised Controlled Trial Number Register.

^*3 split-mouth and parallel-arm; 6 split-mouth crossover.