Are calcium- and phosphate-containing fluoride varnishes more effective than the conventional fluoride varnish in preventing early childhood caries?

Abstract

Early childhood caries (ECC) is a worldwide health issue caused by cariogenic microorganisms present in dental biofilm. A cross-sectional study of 741 preschool children showed that poor oral hygiene is the risk indicator associated with the presence of non-cavitated lesions; while poor oral hygiene, poor parental oral health knowledge and attitude are associated with the presence of cavitated lesions. Topical fluoride is the most recommended preventive strategy for ECC and among the varnishes, 5% sodium fluoride (NaF) is the gold standard. Recently, new 5% NaF formulations have been introduced with additional calcium and phosphate-based remineralizing technology like casein phosphopeptide amorphous calcium phosphate (CPP-ACP) and tricalcium phosphate (TCP), promoting remineralization and inhibiting demineralization. Systematic reviews conducted as a part of this thesis identified the potential research gap regarding the lack of appropriately conducted randomized clinical trials assessing the caries preventive effectiveness of topical fluorides. Therefore, a randomized controlled clinical trial was conducted in 3-4 years old high caries-risk children of Hong Kong, investigating the effectiveness of quarterly application of two novel 5% NaF varnishes containing CPP-ACP and TCP to the conventional 5% NaF varnish in preventing ECC. From 25 kindergartens, 582 children with at least one carious lesion (pre-cavitated or cavitated) were recruited at baseline (T1) and randomly allocated into one of the three intervention groups: Group 1 (Control, n=196)- 5% NaF, Group 2 (Test, n=193)- 5% NaF with TCP, Group 3 (Test, n=193)- 5% NaF with CPP-ACP. The study evaluated the incidence and increment of cavitated and non-cavitated carious lesions. A total of 381 children remained at 24 months (T2), and no significant difference was found among the three intervention groups for the incidence and increment of cavitated and non-cavitated carious lesions. Two microbiological studies were conducted with the clinical trial. The first study compared Streptococcus mutans (S. mutans) and Lactobacillus fermentum (L. fermentum) counts in saliva and biofilm of caries-free children to those with cavitated and non-cavitated lesions through quantitative Real-time Polymerase chain reaction (qRT-PCR). A subgroup of 135 children recruited in the trial were randomly selected and grouped (n=45) according to their caries status: caries-free, with only non-cavitated lesions and with cavitated lesions. The quantity of S. mutans and L. fermentum was significantly higher in saliva and biofilm of children with cavitated lesions, followed by those with non-cavitated lesions and the lowest in caries-free children. In the second study, each group of children (caries-free, with only non-cavitated lesions and with cavitated lesions) were further subdivided into three fluoride varnish intervention groups (n=15) and the varnishes effect on S. mutans and L. fermentum count in saliva and biofilm samples of children collected at T1 and T2 were investigated. No significant difference in salivary and biofilm bacterial levels was observed among the groups according to children’s caries status.

In conclusion, the two calcium- and phosphate-containing NaF varnishes were equally effective in preventing ECC in high-risk preschool children and demonstrated a similar antibacterial effect on S. mutans and L. fermentum counts in both saliva and biofilm as the conventional NaF varnish.