Assessing cutoff values of saliva parameters and oral microbes in dental students

Sammanfattning: ABSTRACT Background: The ability to identify individual risk factors for development of caries areimportant parts in the perspective of being able to control and limit caries disease. One suchcomponent is to establish, cut-off values for normal versus not normal values of known andputative risk factors. Aim: The aim was to analyze if individual variations of the amount of stimulated salivasecretion, pH-level and buffer capacity as well as content of S. mutans and A.actinomycetemcomitans could be used to form an alternative method to reach cut-off valuesbased on the natural variation in a population of dental students. Methods: This study was conducted by collecting saliva from 71 dental students at Umeåuniversity. The saliva was collected three times over a period of five weeks. The collection ofsaliva was conducted pair vice by the students themselves. The saliva was analyzed regardingsaliva secretion rate, buffer capacity, pH-level and quantity of S. mutans and A.actinomycetemcomitans. Measured factors were plotted graphically to show their stabilityover time among the participants. Results: Saliva secretion (and buffering, pH) showed a normal distribution that rangedwidely but with stable intra-individual values, the bacterial factors showed a non-parametricdistribution ranging from negative to positive values that varied largely. Conclusions: The normal distribution of salivatory properties makes it possible to calculatecut-off values based on standard deviation. The non-parametric distribution of the microbialfactors suggests cut-off values based on infected versus non-infected and intra-individuallyhigh numerical counts of bacteria on repeated analysis.