Salivary analyses and caries increment over 4 years: an approach by cluster analysis.

Abstract

Caries as a multifactorial process is influenced by salivary defense. Cluster analyses should give additional information on the role of salivary variables in relation to caries increment. Samples of unstimulated and stimulated whole saliva from 28 young adults (mean age 23.5+/-2.1 years) were analyzed for flow rate, pH and buffer variables, lysozyme, lactoferrin, peroxidase, thiocyanate, secretory immunoglobulin A, and total protein. The decayed, missing, and filled surfaces (DMFS) were recorded at baseline and after 4 years. Cluster analyses were executed on the basis of salivary data. The mean caries increment (DeltaDMFS) over 4 years was 6.7+/-4.0 (range 1-16). In two-cluster processing, three out of four volunteers with low caries increments were grouped into one cluster. Only a few variables proved to be important for cluster characteristics. The results suggest that over 4 years (1) the volunteers with very low caries increment (DeltaDMFS=1) are classified always together, (2) these volunteers do not form a separate cluster by themselves, (3) low caries increment was related to higher salivary flow rate and lower levels of lysozyme and lactoferrin for unstimulated saliva and (4) the partial pressure of CO(2) was of importance in stimulated saliva.