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.