Correlation between salivary urea level and dental caries.

OBJECTIVES The aim of this study was to determine the values of salivary urea in subjects with different caries activity. MATERIAL AND METHOD The planned trials were conducted in 80 children of both sexes, aged 16 years, with different caries activity. Based on the condition of teeth, the DMFT-index, respondents were divided into two groups: the first group consisted of 40 examinees with a low to very low index of caries (0-3), the second group consisted of 40 examinees with a high index of caries (>10). Material for biochemical testing of the saliva sample was taken from all subjects at different time intervals: 5, 30 and 60 minutes from the (daily) meal. The examined parameters were followed in the same examinees in a sample of saliva taken in the morning before consuming any food or implementation of oral hygiene: they represent basic information compared with the results of the examination. The concentration of urea in saliva was determined by the enzyme method of continuous measurement. This method is based on the principle of hydrolysis of urea, using the enzyme urease. RESULTS Salivary concentration of urea, measured fasting in the morning (basic values) in examinees with a low caries index, ranging in limits from 5.50 to 9.10 mmol/l, and significantly lower values in examines with a high DMFT-index (from 3.40 to 5.50 mmol/l). The same was done with the concentration of salivary urea at different time intervals after taking the meal - 5, 30 and 60 minutes in the examinees with a different DMFT-index. With the increasing time interval after taking a meal, the concentration of salivary urea continuously and significantly declines compared to its baseline concentration. The largest decrease of concentration of urea in terms of its basic value in all examinees with a different DMFT-index (with low and high) took place during the 60 minutes after having the meal. CONCLUSION Saliva with its constituents plays an important role in maintaining oral, and exspecially dental health. Urea contributes in maintaining the acidobasic balance of saliva, and thus affects the incidence of caries. The positive effect of urea was confirmed by the values found in this study: the respondents with a lower DMFT-index present a higher concentration of urea than in the basic values, and in the values of stimulated (through the meal) saliva, followed in all intervals.