Relationships between the biochemical composition of both free smooth surface and approximal plaque and salivary composition and a 24-hour retrospective dietary history of sugar intake in adolescents.

The relationships between the composition of both free smooth surface and approximal plaque and salivary composition and sugar intake assessed from a retrospective 24-hour dietary history were investigated. The inorganic phosphorus concentrations of both types of plaque collected from the permanent dentition were directly related to concentrations in stimulated whole saliva of 45 males aged 12-13 years. The calcium, inorganic phosphorus, water-soluble carbohydrate and protein concentrations of free smooth surface plaque were related to both the time since the last reported sugar intake and the amount of sugar and number of sugar intakes consumed in the previous 24 h as assessed from the retrospective diet histories of 75 females aged 14-15 years. A similar relationship with the reported time since sugar was observed for the calcium and carbohydrate concentrations in approximal plaque, but an association with the reported 24-hour sugar intake was not observed. Fewer statistically significant correlation coefficients were observed between the composition of both types of plaque and the reported sugar intake in the male subjects. The results indicate that the composition of both types of plaque are related to the composition of saliva and the time elapsed since the last sugar intake, but the relationship between the composition of plaque and sugar intake may differ between free smooth surface and approximal plaque.