Unstimulated Human Whole Saliva Flow Rate in Relation to Hyposalivation and Dental Caries

Introduction: Salivary secretion is influenced by a large number of factors, including the circadian rhythm, making the detection of reduced salivary flow (hyposalivation) difficult. This is important since severely reduced salivary secretion has been associated with an increased risk for dental caries and may be a sign of a general disease, e.g. Sjögren's syndrom. It has been suggested that iron deficiency is related to hyposalivation. Aims: The aims of this thesis were to investigate i) the unstimulated whole saliva flow rate and serum ferritin among individuals with dental caries, ii) time-dependent changes in the unstimulated whole saliva flow rate in subjects with hyposalivation, and iii) the subjects’ perception of salivary gland function. Results: Caries-active women were found to have a significantly lower unstimulated saliva flow rate compared with those with inactive caries, but there were no significant differences in serum ferritin. A significant increase in unstimulated whole saliva flow rate was revealed for individuals with hyposalivation as well as for those with a normal saliva secretion rate, when tested at two time points separated by four hours in the morning. There were significant differences in subjective assessments of oral dryness between individuals with hyposalivation and individuals with normal saliva secretion. Conclusions: It was concluded that a low unstimulated whole saliva flow rate is related to caries activity, thereby strengthening the view that the unstimulated whole saliva flow rate test could be used in the prediction, prevention and treatment of caries. Furthermore, serum ferritin appears not to be related to caries activity, or to the unstimulated whole saliva flow rate. The unstimulated saliva flow rate test should be performed in a narrow time interval early in the morning in order to obtain an accurate diagnosis of hyposalivation. Individuals with salivary gland hypofunction perceive an increase in saliva flow rate more clearly than those with normal unstimulated whole saliva flow rate.