Aetiology of severe demarcated enamel opacities--an evaluation based on prospective medical and social data from 17,000 children

During the 1970s dentists reported an increasing prevalence of a "new" type of enamel disturbance.The disturbance was very specific, with areas of demarcated hypomineralised enamel, and was mostly found in permanent first molars and incisors. Several studies have tried to reveal the aetiology behind the enamel disturbance but sofar no clear factors correlated have been found. The aim of the present study was to evaluate aetiological factors to severe demarcated opacities (SDO) in first permanent molars in a large cohort of children enrolled in the "All Babies in Southeast Sweden" (ABIS) project. ABIS is a prospective study of all children in five Swedish counties born between Oct 1, 1997 and Oct 1, 1999, in all about 17,000 children.They have been followed from birth with recording of a large number of factors on nutrition, diseases, medication, infections, social situation etc. With help from 89 Public Dental Service clinics in the same area preliminary examinations of the children, born between Oct 1,1997 and Oct 1,1999, reported 595 children with severe demarcated opacities (SDO) in first molars.These children and a randomly selected age matched group of 1,200 children were further invited to be examined by specialists in paediatric dentistry. At these examinations 224 severe cases were identified as well as 253 children completely without enamel disturbances among children registered in ABIS.These two groups were analysed according to any correlation between SDO and variables in the ABIS databank. The analyses showed no association between SDO and pre-, peri-, and neonatal data. However, we found a positive association between SDO and breastfeeding for more than 6 months (OR 1.9; 95% CI 1.1-3.2), late introduction of gruel (OR 1.9; 95% CI 1.1-2.9), and late introduction of infant formula (OR 1.8; 95% CI 1.2-2.9). A combination of these three variables increased the risk to develop SDO by more than five times (OR 5.1; 95% CI 1.6-15.7). No significant associations were found to other environmental, developmental, or medical factors. We conclude that nutritional conditions during first 6 months of life may influence the risk to develop severe demarcated opacities in first permanent molars.