Chesters 2002.

Methods	Trial design: 2‐armed, double‐blind, active‐controlled and stratified RCT Location: Lithuania Number of centres: 28 secondary schools in Vilnius, Lithuania Recruitment period: study commenced in 1999
Participants	Inclusion criteria: ≥ 1 erupted second permanent molar; CVA D3MFS score of 2 to 24 Exclusion criteria: low‐caries subjects; parent/guardian unwilling to disclose medical/dental history; intra‐oral x‐ray for caries diagnosis in prior 6 months; > 2 occlusal surfaces in second permanent molars restored/clinically cavitated/sealed; conduct of oral examination liable to cause unacceptable stress to participant; medical/dental conditions with potential to affect caries development (including antibiotic therapy); heart condition; cancer treatment receipt; fixed orthodontic appliances present at baseline prohibiting assessment of all erupted teeth Baseline caries: baseline characteristic (baseline caries) "well balanced." Baseline values D3MF not reported but ''not statistically different". Baseline D1MFS for assessed participants at 24 months: 32.48 D1MFS (Gp A: mean 32.95 (SEM 0.40); Gp B: mean 32.01 (SEM 0.37)) Age at baseline (years): range 11 to 14 years, mean 13 years (Gp A: 13.0; Gp B: 13.1) Sex: 1330 F:1057 M (Gp A: 665 F:528 M; Gp B: 665 F:529 M). Baseline characteristic (sex) "well balanced" Any other details of important prognostic factors: background exposure to fluoride not reported Number randomised: 2387 (Gp A: 1193; Gp B: 1194) Number evaluated: 2011 at 2 years (present for final assessment. Gp A: 994; Gp B: 1017) Attrition: 15.8% dropout (for all study groups combined) after 2 years. Gp A: 16.7%; Gp B: 14.8%. Reasons for attrition absent from assessment (Gp A: 24, Gp B: 17); withdrawn (Gp A: 175, Gp B: 160)
Interventions	Comparison: FT versus FT Gp A (n = 1193): SMFP 1000 ppm F; silica abrasive system; home use twice daily/unsupervised; daily brushing at school Gp B (n = 1194): SMFP 2500 ppm F; silica abrasive system; home use twice daily/unsupervised; daily brushing at school
Outcomes	Primary: 2‐year net DMFS increment cl(DSTM) FOTI at D3 all radiographic lesions; D1MFS increment (DSTM only); D3MFS increment (DSTM only); D1MFS events (DSTM); D3MFS events (DSTM). Reported at 1 and 2 year follow‐ups Secondary: none assessed Assessments irrelevant to this review's scope: none Follow‐up duration: 2 years
Notes	Adverse effects: not reported Funding source: "funded by Unilever Dental Research" Declarations/conflicts of interest: 5 (including lead author) of 14 authors employed by Unilever: RK Chesters, E Huntington, JR Matheson; JA Nicholson, D Savage Data handling by review authors: n/a Other information of note: examinations carried out by a single examiner. Intra‐examiner reliability: repeat DSTM and FOTI examinations held throughout the baseline, 12 and 24 month examinations on 5% to 10% of subjects. For radiography, baseline and 12 and 24 month radiographs re‐assessed for 5% to 10% of subjects. Reproducibility "excellent", Kappa values > 0.8
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quotes: " . .randomized to one of two silica‐based dentifrices" and "...stratified into 12 strata ...allocated to a product group according to a pre‐prepared list of randomized blocks?"
Allocation concealment (selection bias)	Unclear risk	Comment: insufficient information
Blinding (performance bias and detection bias) All outcomes	Low risk	Quotes: "... double‐blind study" and "Neither the subjects, clinical examiners, nor those distributing the test products were aware of the product identities at any time during the trial. The investigators were supplied with sealed code‐break envelopes that could be opened in an emergency. This was not required and the integrity of the product code was confirmed with regular GPC monitoring and independent audit" and "The products were identical except for the fluoride level and different coloured packaging for each product code?"
Incomplete outcome data (attrition bias) All outcomes	Low risk	2387 randomised (994/1193 included in final main analysis in low fluoride group; 1017/1194 in high fluoride group) Comment: not unreasonable dropout rate; similar in both groups. Reasons unlikely to be due to intervention. Numbers absent and withdrawn are given for each group. Well balanced between groups. No further information about dropouts given
Selective reporting (reporting bias)	Unclear risk	Comment: results reported traditional increment and DSTM increment at different levels of diagnosis. DMFT and proportion developing new caries missing. DSTM, FOTI and radiographic assessments
Baseline characteristics balanced?	Low risk	Comment: balance of sex and baseline DMFS
Free of contamination/co‐intervention?	Unclear risk	Comment: unlikely as used different colours for toothpaste tubes/cartons, but possibility of contamination during school brushing sessions