Mella 1992.
| Methods |
FLUOROSIS STUDY Country of study: Chile Geographic location: students attending 2 boarding institutions in Santiago, who lived in areas throughout Chile Year of study: not stated Year of change in fluoridation status: NA Study design: cross‐sectional |
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| Participants | Inclusion criteria: students at boarding institution, exposure estimated from home fluoride level; lived for first 6 years in home town Exclusion criteria: students who could not remember the areas in which they spent the first 6 years of their life Other sources of fluoride: not stated Social class: distribution of subjects by high, moderate, low social class, but no significant differences between fluoride groups Ethnicity: not stated Residential history: first 6 years of life Other confounding factors: years lived in city of birth |
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| Interventions | All natural fluoridation Group 1: > 0.3 ppm Group 2: ≤0.3 ppm | |
| Outcomes | Dental fluorosis (Dean's Index) Age at assessment: 19 years |
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| Funding | Not stated | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Sampling | High risk | All subjects were selected from 2 boarding schools. Insufficient detail reported to determine how sampling took place |
| Confounding | High risk | Did not account for the use of fluoride from other sources |
| Blinding of outcome assessment (detection bias) All outcomes | High risk | Insufficient information |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Data presented for all participants |
| Selective reporting (reporting bias) | Unclear risk | Unclear why only very mild, mild and moderate severities of dental fluorosis reported for both groups |
| Other bias | Low risk | No other apparent bias |