Holm 1979.
| Methods | Design: 2‐arm quasi‐RCT Location: Sweden Study started: Not reported |
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| Participants | Number randomised: 250 (125, 125) Number analysed: 225 (112, 113) analysed at 2 years (available at final examination) Age range: Mean and median 3 years Background exposure to other fluoride: 0.3 ppm water fluoridation. At 5 years of age "no differences in toothbrushing frequency, regular use of fluoride tablets or use of fluoridated toothpaste" |
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| Interventions |
Comparison: FV + ptc versus NT + ptc
Group 1 (n = 125): NaF varnish group (Duraphat® 22,600 ppm F), applied twice a year, with thin brush, left to dry (duration NR) Group 2 (n = 125): No treatment Post‐op instructions: No hard food or toothbrushing until following day |
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| Outcomes | 2‐year defs increment ‐ (E) (CA)cl + (DR)xr Reported at 1 and 2 years follow‐ups: O‐defs; MD‐defs; BL‐defs; ds (NCA); proportion of children with 1 or more new defs (at CA level); drop‐outs | |
| Notes | Baseline characteristics (defs) unbalanced, 1.05 in FV, 0.71 in NT Clinical (VT) caries assessment by 1 examiner; diagnostic threshold = CA and NCA; state of tooth eruption included = E. Radiographic assessment (if required) by 1 examiner; diagnostic threshold = DR. Diagnostic errors NR | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | High risk | Quote: "At baseline examination, every other child was assigned to the test group and the remainder to the control group" Comment: Not randomised. Alternation used to allocate into groups |
| Allocation concealment (selection bias) | High risk | No information provided. However, the non‐random method used for allocation would not allow for allocation concealment |
| Blinding of participants and personnel (performance bias) All outcomes | High risk | Quote: "Fluoride varnish was applied to the teeth of the children in the test group......No placebo treatment was performed in the control group" Comment: No placebo described. Parents were not aware, however, that their children were taking part in any experiment and regarded the treatment as a routine part of the Public Dental Health Service given to all children |
| Blinding of outcome assessment (detection bias) All outcomes | Low risk | Quote: "Annual caries exam was performed by the same examiner and was single blind" Comment: Blind outcome assessment |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Overall drop‐out for length of follow‐up: 10% in 2 years. Drop‐outs by group: 13/125 FV, 12/125 NT. Reason for losses: Moving out of town 13 FV, 12 NT Comment: Numbers lost were not unduly high for the length of follow‐up, were reported by group and showed no differential losses between groups. The only reason reported for missing data is acceptable and balanced between groups. Caries data pertain to participants present at final examinations |
| Selective reporting (reporting bias) | Low risk | Outcomes reported: defs increment ‐ (E) (CA)cl + (DR)xr, at 1 and 2 years follow‐ups; O‐defs, MD‐defs, BL‐defs, ds (NCA); proportion of children with 1 or more new defs (at CA level); drop‐outs Comment: Trial protocol not available. All pre‐specified outcomes (in Methods) were reported and were reported in the pre‐specified way |
| Baseline characteristics balanced? | High risk | Prognostic factor reported: ds (CA): 1.05 (2.34) FV, 0.71 (1.62) NT; ds (NCA) 1.16 (3.11) FV, 0.59 (1.81) NT Mean age: 3 years (both groups) Comment: Initial caries appears unbalanced between groups |
| Free of contamination/co‐intervention? | Unclear risk | Quotes: "After each annual examination the child was given dental treatment by the Public Dental Health Service if necessary" and "...children in the test group had two more appointments with the dentist during these 2 years......." Comment: These more frequent visits might have made both children and dentists rather more concerned about dental health cannot be totally excluded |