Immunohistochemical study on antigen-presenting cells in healthy and carious human teeth.

Class II major histocompatibility complex (MHC) antigen-presenting cells are associated with the early phase of the immune response. We have studied the distribution of class II-expressing cells in developing, healthy and carious human teeth to clarify, when human pulp acquires an immunologic defense potential and how this reacts to dental caries. Antigen-expressing cells were identified immunohistochemically with the following monoclonal antibodies: HLA-DR - for dendritic cells and CD68 - for macrophages. In the pulp of unerupted developing teeth, HLA-DR-positive cells were distributed mainly in and around the odontoblast layer. A few CD68 positive cells were located more coronary around the blood vessels. In erupted teeth, HLA-DR-positive cells were located, for the most part, just beneath the odontoblast layer. CD68 positive cells were also located coronary, mainly around the blood vessels. Superficial caries lesions caused an aggregation of HLA-DR-positive cells and macrophages in the dental pulp corresponding to the lesion. These findings showed that: (1) human teeth are already equipped with an immunological defense potential prior to eruption; (2) in the initial stage of caries infection, an immuno-response mediated by class-II-expressing cells is initiated in human dental pulp (Fig. 8, Ref. 33).

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.