Intra- and inter-individual variation in salivary flow rate, buffer effect, lactobacilli, and mutans streptococci among 11- to 12-year-old schoolchildren

Abstract

Both intra- and inter-individual variation in salivary flow rate, buffer effect, and the levels of salivary mutans streptococci and lactobacilli were analyzed in 128 11-year-old children. The follow-up period was 9 months, with six saliva samplings done at regular intervals. Inter-individual variation was relatively large in paraffin-stimulated salivary flow rate: low (< 1.0 ml/min) and high (> or = 2.0 ml/min) flow rates were measured in 18% and 13% of the children, respectively. Intraindividual variation during the follow-up period was found in 63% of the boys and in 73% of the girls. The buffer effect stayed stable in all samplings in 59% of the boys and in 42% of the girls. Buffer effect was significantly (p < 0.001) lower in girls than in boys. Mutans streptococci were analyzed by a chair-side method (Strip mutans test) and by cultivation on mitis-salivarius-bacitracin (MSB) agar plates. The results of the two methods correlated highly significantly (r = 0.79, p < 0.001). With the Strip mutans test no variation in test scores occurred in 49% of all subjects in all six samplings, whereas the respective percentage for MSB scores was only 19%. No variation in salivary lactobacilli occurred in only 18% of the subjects, and in 13% the intraindividual variation was as high as > or = 3 logs. These results show that in young teenagers with a developing dentition, simultaneous changes in behavioral, hormonal, and dietary factors make single-point measurements of salivary factors too unreliable for caries-diagnostic or predictive purposes.

Salivary Biomarkers in Caries Affected and Caries Free Children

“…Other studies support our finding as they have reported that larger quantities and faster rates of acid production in caries active individuals than that in caries-free individuals [41,42]. There is strong evidence showing that salivary buffering capacity protects the tooth from dental caries [43] and low buffering capacity is usually associated with caries development because of its impaired neutralization of plaque acids and reduced remineralization of early enamel lesions [44][45][46]. This association between low caries levels and high salivary buffering capacity has been demonstrated [47,48] and individuals with a high salivary buffer capacity are often cariesresistant [11].…”

Effect of plaque accumulation and salivary factors on enamel demineralization and plaque composition in situ

“…Nevertheless, we did not find any relationship between the biochemical salivary factors assessed at baseline and the subsequent enamel demineralization observed. These findings are in agreement with those of some authors 9 but differ from the results of others 19 . Our data support the report that the association between these factors and caries activity is weak, suggesting their use in a longitudinal and regular follow-up of a patient 18 , rather than as caries predictors.…”

“…However, the low levels of mutans streptococci found in the saliva of the volunteers may have contributed to the lack of relationship found in this study. Using populations with wide-ranging levels of mutans streptococci in saliva, some studies were able to find a relationship between them and present or future dental caries experience 9,19 . In addition, the present study also did not find a relationship between enamel demineralization and the proportion of mutans streptococci in the plaque formed (Table 2).…”

“…Salivary flow rate, buffer capacity and mutans streptococci counts were significantly related to caries occurrence in some studies 9,19 , and the evaluation of these factors has been proposed as a tool for caries risk assessment; but the associations with caries are normally weak. Also, mutans streptococci counts in plaque are considered to be indicative of caries activity 10 , although an inconsistent relationship between numbers of mutans streptococci in plaque and caries state of enamel beneath it has been found in some studies 21 .…”

Caries Prediction by Multiple Salivary Mutans Streptococcal Counts in Caries–Free Children with Different Levels of Fluoride Exposure, Oral Hygiene and Sucrose Intake

“…If the salivary ms level of a subject were permanently high, the exposure time and, therefore, the risk for caries would be higher than if the level fluctuated [Manji and Nagelkerke, 1990]. For this reason, multiple salivary samples have been collected from each individual, with varying intervals ranging from hours to months [Togelius et al, 1984;Matee et al, 1985;Bentley et al, 1988;Bratthall and Carlsson, 1989;El Nadeef and Bratthall, 1991;Tukia-Kulmala and Tenovuo, 1993;Petti and Tarsitani, 1998]. …”