Porciani 2010.

Methods	Title: effect on dental stain occurrence by chewing gum containing sodium tripolyphosphate Trial design: double‐blinded, parallel‐group, randomised controlled trial Location: not reported Language: English Number of centres: 1 Recruitment period: not reported Funding source: Perfetti van Melle
Participants	Participants: 18 to 54 years old. Mean age 28.9 years Total number: 111 Inclusion criteria: presence of all anterior teeth no more than 3 restorations no orthodontic treatment Lobene stain index between 0.33 and 1.5 Exclusion criteria: diabetes or systemic disease oral and facial pain sensitivity to polyphosphate‐containing dentifrices Number randomised: 111 Method of randomisation: random table Method of allocation concealment: not reported Method of blinding: similar looking package, shape, flavour and weight of the chewing gum. Participants instructed not to discuss the treatment they were receiving Number evaluated: 108. 3 participants dropped out from experiment group
Interventions	Total number of intervention groups: 2 Experimental: sodium tripolyphosphate (1%) containing gum Control: placebo Duration of treatment: 6 weeks
Outcomes	Reduction in stain intensity and extent of stain Lobene modified index: smaller value shows improvement Stain composite index: smaller value shows improvement
Notes	Sample size calculation: not reported Adverse effects: not reported Health‐related quality of life: not reported Key conclusions of the study authors: "This trial showed a reduction in dental stain by a chewing gum containing sodium tripolyphosphate after 6 weeks" Contact: PF Porciani, piercateadsl@libero.it
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Each subject entered in the test or control group using a random table .."
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "Both chewing gums had the same flavour, weight, shape, colour, and packaging so that the participants were blinded as to the identity of the gum" Comment: additionally, participants were instructed not to tell other subjects to which group they were assigned in order to minimize inadvertent disclosure to the study participants and staff
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "Data were scored by the same blinded operator for all measurements"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "... 3 eventually dropped out, though the cause was unrelated to polyphosphates" Comment: plausible effect size (difference in means ) among missing outcomes not enough to have a clinically relevant impact on observed effect size
Selective reporting (reporting bias)	Low risk	All outcomes mentioned were reported adequately. Conclusion reflected study results (in the abstract)
Other bias	Low risk	None