Added calcium and phosphate in fluoride varnishes no silver bullet for fighting kids’ tooth decay, study finds

In a recent study published within the journal Scientific Reports, researchers examined the impact of sodium fluoride varnishes containing phosphate and calcium on the Streptococcus mutans and Lactobacillus fermentum counts in children without caries and with caries with and without cavitated lesions and compared it to the impact of conventional sodium fluoride varnishes.

Study: Effect of fluoride varnishes on oral bacteria of preschool children with cavitated and non-cavitated carious lesions: randomized clinical trial. Image Credit: Created with the help of DALL·E 3

Background

Early childhood caries is extremely prevalent in children worldwide, and bacterial growth in dental biofilms is the etiological basis of this multifactorial microbial disease. Moreover, despite the substantial emphasis on dental health, hundreds of thousands of youngsters suffer from caries of their primary teeth. The break in the whole enamel continuity is graded for severity based on the presence or absence of cavitated lesions. Various studies have examined the role of demineralization within the formation of cavitated lesions, but there may be a paucity of longitudinal studies examining how non-cavitated lesions grow to be cavitated.

The demineralization of the tooth enamel occurs when the biofilm microorganisms interact with sugars and produce aids that reduce the pH of the tooth surface and result in the lack of phosphate and calcium ions. Saliva exerts some protective effects due to its antimicrobial properties, mineral ion content, and skill to neutralize the pH. Nonetheless, the presence of pathogenic microbes resembling L. fermentum and S. mutans plays a major role within the occurrence and development of caries, and these microbes are considered risk markers for early childhood caries.

Concerning the study

In the current study, the researchers compared the effectiveness of sodium fluoride varnishes with phosphate and calcium against that of conventional sodium fluoride varnishes in reducing the L. fermentum and S. mutans counts within the biofilm and saliva of preschool children without caries and with caries having non-cavitated or cavitated lesions. In addition they used a quantitative real-time polymerase chain response (qRT-PCR) approach with species-specific primers to detect the pathogenic microbe quantities accurately.

Participants were recruited for the study from non-profit kindergartens in Hong Kong using a random sampling method. They included children between the ages of three and 4 with no prior medical conditions, long-term medication requirements, or special health needs. Those that had undergone antibiotic treatment of any kind for the past month or skilled fluoride treatment anytime within the previous six months, had primary teeth enamel hypoplasia, were sensitive to any of the varnish constituents, or were uncooperative in the course of the study were excluded.

The caries diagnoses were made by a dentist based on the International Caries Detection and Assessment System II. The youngsters were divided into three groups — those without caries, those with caries but non-cavitated lesions, and people with cavitated carious lesions. The intervention initially consisted of eight applications of the chosen varnish applied every 4 months for twenty-four months, but because of the coronavirus disease 2019 (COVID-19) pandemic-related school closures and safety concerns, it needed to be reduced to a few to 6 applications.

Saliva and supragingival biofilm samples were collected at baseline and follow-up for deoxyribonucleic acid (DNA) extraction and qRT-PCR evaluation. Species-specific oligonucleotide primer pairs were used to quantify L. fermentum and S. mutans from all of the samples, and samples that had cycle threshold (Ct) values below the detection level determined by the DNA standard curves were considered negative.

Results

The findings suggested that sodium fluoride varnishes containing calcium and phosphate didn’t significantly improve the L. fermentum and S. mutans counts present in saliva and biofilm samples compared to standard sodium fluoride varnishes.

Nonetheless, while previous studies have examined the impact of fluoride varnishes on the biofilms of youngsters with and without caries, they’ve not explicitly examined the differences in microbial levels between non-cavitated and cavitated lesions. The current study examined the three groups of youngsters individually. It used a precise qRT-PCR technique to quantify the bacterial counts, which sheds more light on the role of the microbiota within the establishment and progression of caries.

Conclusions

To summarize, the study compared the impacts of conventional sodium fluoride varnishes with those containing added phosphate and calcium in reducing the L. fermentum and S. mutans counts in saliva and biofilm samples from preschool children. The outcomes showed that sodium fluoride varnishes with added phosphate and calcium are usually not significantly different from conventional sodium fluoride varnishes in reducing bacterial growth within the biofilms, and this highlights the necessity for more research to seek out effective ways to manage early childhood caries.