PSYCHOLOGICAL STRESS AS A DETERMINANT OF PROTEIN-LEVELS AND SALIVARY-INDUCED AGGREGATION OF STREPTOCOCCUS-GORDONII IN HUMAN WHOLE SALIVA

Several pathologies of the oral cavity have been associated with stres s, so we investigated salivary-induced aggregation during psychologica l stress. In addition, salivary total protein, alpha-amylase, and secr etory immunoglobulin A (s-IgA) were assessed. In this longitudinal stu dy, 28 dental students provided unstimulated whole saliva during 10 mi nutes before an academic examination and subsequently 2 weeks and 6 we eks later in a nonstress situation. The effect of whole saliva on the aggregation of Streptococcus gordonii (HG 222) was determined spectrop hotometrically. The results show a significant stress-mediated increas e of salivary total protein concentration, alpha-amylase activity, amy lase/protein ratio, alpha-amylase output, s-IgA concentration, and s-I gA output. There was also a trend for increased total protein output, whereas salivary flow rate was unchanged. The aggregation of S. gordon ii in whole saliva collected before examination was 13.1%, whereas the aggregation in whole saliva collected during nonstress was 23.3%, Thi s reduction was statistically significant (p < .01). Furthermore, the decrease in bacterial aggregation was related to the increase in state -anxiety (p < .05). The reduction in aggregation of S. gordonii under stress was not correlated with changes in salivary flow rate, s-IgA co ncentration, total protein concentration, or alpha-amylase activity. T hese results suggest that acute psychological stress exerts its influe nce on both salivary composition and salivary function. Reduced bacter ial aggregation may be a contributing factor in the often reported rel ationship between stress and impaired oral health.