Dolles 1980.

Methods	Stratified random allocation; double‐blind (A); placebo‐controlled; 22% natural drop out after 2 years (study duration = 2 years). Reasons for attrition described with numbers by group: unacceptable staining (3,4), unacceptable taste (2,0), change of residence (0,2), other reasons/lack of co‐operation(1,1); exclusions based on presence in all follow‐up examinations; no differential group losses.
Participants	47 children analysed at 2 years (present for all examinations). Average age at start: 13 years. Surfaces affected at start: NR. Background exposure to fluoride: none. Year study began: 1974. Location: Norway.
Interventions	FT(Chlor) versus PL(Chlor) ** (NaF toothpaste = 500 ppm F). Home use/unsupervised, daily frequency assumed (instructed to brush for 2 min twice a day). Abrasive system: plastic particles.
Outcomes	2yDS increment ‐ (CA)cl+(ER)xr. Reported at 2 years follow up. Proportion of children with new carious surface.
Notes	Participants randomised (N = 60). Baseline characteristics NR. Clinical (VT) caries assessment, diagnostic threshold = CA; state of tooth eruption included NR. Radiographic assessment (postBW), diagnostic threshold = ER. Diagnostic errors NR. **Chlorhexidine present in both, the fluoride and the non‐fluoride toothpaste groups (other outcomes measured, such as tooth staining, not considered relevant for the comparison of interest).
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear