Al‐Alousi 1975.
| Methods | FLUOROSIS STUDY Country of study: England Geographic location: Anglesey (F); Leeds (non‐F) Year of study: 1973 Year of change in fluoridation status: 1955 Study design: cross‐sectional | |
| Participants | Inclusion criteria: lifetime residents of study areas; children aged 12‐16 years Exclusion criteria: missing, fractured or crowned teeth; refusal to participate (1 school in Leeds) Other sources of fluoride: not stated Social class: not stated Ethnicity: not stated Residential history: lifetime residents Other confounding factors: not stated |
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| Interventions | Group 1: 0.9 ppm (artificial fluoridation) Group 2: < 0.01 ppm (natural fluoridation) | |
| Outcomes | Dental fluorosis Age at assessment: 12‐16 years |
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| Funding | Not stated | |
| Notes | Data extracted from Al‐Alousi 1975 differs from that presented in CRD review | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Sampling | Unclear risk | Children were selected from schools in Leeds in a quasi‐random way whereby every nth child (n = total children in school/20) from the register was selected. Eligible children in Anglesea were selected from schools randomly |
| Confounding | High risk | Did not account for use of other fluoride sources or SES |
| Blinding of outcome assessment (detection bias) All outcomes | High risk | A clinical investigation and double‐blinded photographic examination were conducted. However, the results reported are those of the unblinded clinical investigation |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Data presented for all participants |
| Selective reporting (reporting bias) | Unclear risk | Outcome of interest reported |
| Other bias | High risk | Diagnoses had to be "agreed" on by the two examiners and there was no mention of any sort of calibration of the examiners. This may have resulted in measurement bias |