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 th e duration of vomiting. Possible changes in the buffering and lubricat ing role of saliva in bulimia nervosa and their relationship to erosio n have not been previously investigated. Chewing-gum-stimulated saliva ry flow rate, pH, bicarbonate concentration and viscosity were compare d between two groups of vomiting bulimics and with 10 healthy controls . One bulimic group (n = 9) had pathological tooth wear present accord ing to the criteria of the Tooth Wear Index and the other bulimic grou p (n = 10) did not. The influence of salivary pellicle on enamel acid dissolution by perchloric acid was also assessed by an enamel biopsy m ethod. Bicarbonate was measured in a Natelson microgasometer. Both the bulimic groups had mean initial 3-min flow rates and overall 9-min fl ow rates significantly lower (p<0.01) than the healthy subjects. The m ean pH values were not significantly different between the two bulimic groups or the control group. However, the mean bicarbonate concentrat ion in both bulimic groups was significantly less (p < 0.01) than in t he 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 m ore calcium was released from the pellicle-free surface in both groups but this was not statistically significant, whilst the dissolved calc ium in enamel biopsies was significantly lower (p<0.05) in the tooth-w ear-present group.