Oral health in children and adolescents - effects on oral microflora and dental caries with focus on genetic and dietary factors.
The overall purpose of the present project is to decode host, diet and microbial factors that lay behind the individuality in dental caries manifestation and to contribute nouvelle strategies in caries prevention.
A healthy mouth includes both the microenvironment and host characteristics. Some bacteria produce disease more than others, and the interaction between bacteria is more and more important. The fact that nutrition is important for the development of caries is well known, also, that a low pH environment gives greater risk to caries because we know that bacteria that are involved prefer low pH environments.
Frequent intake of products with high content of fermentable carbohydrates, increase the risk of caries as they feed the bacteria and acids are produced, which decrease the pH. Carbohydrate-rich products, mainly products with sucrose, are not only harmful to the teeth and oral health; they are also bad for the general health. What drives ”sweet tooth" or why an individual eats a particular product is not known, but it is probably a combination of genetics and environment.
Taste is something that is perceived differently, both at individual and population level. What concentrations needed to detect a taste (threshold) vary, as well as what flavour and what flavour concentration that is preferred. Studies have shown that caries can be associated with genetic factors for sweet and bitter taste. The genetic factors also seem to characterize eating behavior. Generally, very little research has been done about this and the studies available are largely difficult to compare and the results vary. The purpose of this study is to investigate the relationship between polymorphism in sweet, sour and bitter taste coding genes and taste preferences, dietary choices, oral microbiota, and caries in children and Swedish adolescents.
In the first and finalized part of this study, it was concluded that young people with caries experience have a higher and more frequent intake of sweet products, snacks and tobacco. The individuals with high sugar intake have elevated levels of known caries bacteria (Streptococcus mutans and Lactobacilli). This is unlike individuals with low experience of caries with lower sugar intake and higher intake of milk products. The intake of milk products seems to play a role in the composition of the oral microbiota where a low intake correlates with, for example, higher amount of Streptococcus mutans. In the same study, we could conclude that those who drank a lot of milk showed an increased intake of sweet products (mainly cakes and buns), which may indicate an eating behavior that is linked to the Swedish "fika culture". With this in mind, we consider it important to evaluate genetic taste preferences in relation to socially and environmentally conditioned taste preferences. About 200 19-year-olds, all re call patients at Folktandvården in Umeå, are recruited consecutively in connection with the regular re call visit. During the visit, an examination is conducted according to standard practice and caries is noted in addition to routine registration in the form of DeFS and ICDAS. During the visit, two digital surveys, one with questions focusing on nutritional, public health and medication and one with focus on taste preference are answered. Participants also take part of a taste-test of the tastes sour, bitter and sweet in different concentrations to get the threshold and value for preferred flavor. Stimulated whole saliva is collected as well as dental plaque from six different segments of the dental arch. Before freezing the collected saliva, 1 ml of is taken for the cultivation of mutant streptococci and total streptococci. The remaining saliva is stored in an -80 freezer. qPCR is performed for Streptococcus mutans and Scardovia wiggsiae. DNA is extracted from saliva pellets, plaque samples and positive controls in the form of three mock communities and a negative control of sterile water. Extracted DNA is then sequenced using Illumina MiSeq, the variable regions V3-V4 of 16S rDNA, and then determined taxonomically. Human genetic mutation for taste genes is performed with DNA isolated from saliva from all participants by genotyping using the Illumina iPLEX technology, for a total of 134 SNPs within genes that code for receptors for sweet, sour and bitter.