Variations in salivary caries protective functions in healthy individuals

The importance of saliva qualities to caries defense has been previously emphasized. Objectives: Study hypothesis: even in healthy individuals caries defense functions vary widely and are interrelated. Methods: Under standardization (no smoking, toothbrushing, eating, drinking for 60 min), following functions were studied: saliva flow rates (ml/min), stimulated saliva buffer capacity (scores 0-12), resting saliva pH (5.0 to 7.8). Saliva-Check kits were used for the pH and buffer capacity assessments. Glucose clearance (in M) was measured by glucose monitor at 3, 5, and 7 minutes after the glucose rinse. A fluoride retaining rate (in M/L) assessed at 0min, 5min, 10min, 15min and 20min after the 0.2% fluoride rinse. Counts of Mutans Streptoccocus and Lactobacilli in saliva grouped subjects into low, moderate or high caries risk groups. A convenience sample included healthy subjects (no diseases, neither medication use). The biological functions were related by Pearson correlation and significance set at P<0.05. Results: The resting saliva flow rate varied from 0.20 ml/min to 1.17 ml/min, the stimulated saliva from 0.33 ml/min to 3.11ml/min, pH values were from 5.0 to 7.8 and buffer capacity scores from 6 to 12. The fluoride retaining rate varied most at 5minutes and least at 15 minutes after the fluoride rinse. There was a wide range of variation in glucose clearance patterns at all follow-up periods. These functions were interrelated (coefficient, P-value): the flow rate of resting with the pH of resting saliva (0.485, P=0.049) and the buffer capacity with glucose clearance time (0.626, P=0.012). Subjects with low and moderate risk caries groups presented better values of protective functions than subjects with high caries risk. Conclusion: A wide variation in each of studied protective functions was observed in healthy individuals. The protective functions such as pH, flow rate, buffer capacity and glucose clearance presented related effects.