Thesis supervisors: professor Mare Saag (TÜ stomatooloogiakliinik), professor Eino Honkala (Faculty of Dentistry, Kuwait University), professor Kauko K. Mäkinen (Institute of Dentistry, University of Turku, Finland)
Opponent: emeriitprofessor Heikki Murtomaa (Institute of Dentistry, University of Helsinki)
Dental caries is a globally occurring disease. The caries index in Estonia, especially among children, is still high. Caries is a dynamic, prolonged process, and therefore, needs long-term caries prevention methods. The replacement of cariogenic sugars with non-cariogenic substances, like xylitol or other less cariogenic sugar alcohols, is one way to reduce the risk of caries. Previous studies about the effect of xylitol on caries prevention have demonstrated evidence-based success but the preventive effect of other polyols has not always been confirmed or approved.
The interest of this clinical trial was to identify the prevalence of caries among elementary school level children and to investigate and compare the influence and effectiveness of the long-term consumption of different polyols (xylitol, erythritol and sorbitol as a positive control) on mixed dentition. The study was designed as a double-blind randomised controlled prospective clinical trial with 3-year intervention (polyols consumption) which included annual clinical examination of the participants in the Department of Stomatology at the University of Tartu.
We found that the prevalence and experience of caries among elementary school children in south-eastern Estonia is high (which matches previous studies) and increases rapidly - there is a statistically significant difference between first and the second graders, this age group needs intensive caries prevention programmes. Lower second primary molars and the first permanent molars are the most frequently affected teeth in mixed dentition. Dental caries starts in fissures, predominantly shortly after the eruption of the teeth which may be prevented using sealants, but the number of sealants among the examined children is extremely low.
As previous studies have proven the caries decreasing effect of xylitol, the modest role of xylitol in this study is difficult to explain. One probable explanation could be insufficient consumption per day – 3 times per school day against 4–5 regular, daily intake, which has been generally recommended.
Caries progress was slower in the erythritol group compared to the sorbitol and xylitol groups and the effect was apparent after 2 years of erythritol lozenge consumption. Erythritol consistently reduces the amount of dental plaque, the levels of acids in dental plaque and the counts of Streptococcus mutans compared with sorbitol and xylitol lozenges.
We can conclude that erythritol is a well tolerated sweetener which has high potential in caries reduction through controlling plaque quality and quantity. Based on the results obtained, erythritol based lozenges could be recommended to replace sugar containing candies to prevent dental caries in children.