Salivary factors in vomiting bulimics with and without pathological tooth wear

The increased occurrence of dental erosion from self-induced vomiting in bulimia nervosa is not linearly associated with the frequency or the duration of vomiting. Possible changes in the buffering and lubricating role of saliva in bulimia nervosa and their relationship to erosion have not been previously investigated. Chewing-gum-stimulated salivary flow rate, pH, bicarbonate concentration and viscosity were compared between two groups of vomiting bulimics and with 10 healthy controls. One bulimic group (n = 9) had pathological tooth wear present according to the criteria of the Tooth Wear Index and the other bulimic group (n = 10) did not. The influence of salivary pellicle on enamel acid dissolution by perchloric acid was also assessed by an enamel biopsy method. Bicarbonate was measured in a Natelson microgasometer. Both the bulimic groups had mean initial 3-min flow rates and overall 9-min flow rates significantly lower (p < 0.01) than the healthy subjects. The mean pH values were not significantly different between the two bulimic groups or the control group. However, the mean bicarbonate concentration in both bulimic groups was significantly less (p < 0.01) than in the control group. The mean salivary viscosity of 7.4 centipoise (cP), measured by a DV1 Brookfield viscometer, was significantly greater (p < 0.05) in the pathological tooth-wear-present group than in the tooth-wear-absent group (4.5 cP) and the control group (4.1 cP). Slightly more calcium was released from the pellicle-free surface in both groups but this was not statistically significant, whilst the dissolved calcium in enamel biopsies was significantly lower (p < 0.05) in the tooth-wear-present group.