What Is the Purpose of Fluoride to Prevent Dental Caries?
Dental caries is a multifactorial disease, the causative elements being the host defense and immunity, the interaction of oral microflora, and the type of diet adopted. Dental research now understands and elaborates the theory of caries formation in the tooth enamel. Fermentable carbohydrates combine with the biotin formation in the tooth enamel and produce a mineralized loss of tooth structure, the calcium hydroxyapatite crystals, thus initiating and precipitating decay over time.
Fluoride remains the only essential element that can induce or precipitate the mineral formation of the tooth structure in the form of fluorapatite crystals. However, the fact remains that fluoride in toothpaste, lozenges, mouthwash, and remineralized pastes can neither prevent the biofilm formation occurring in the tooth nor impact the acid produced due to fermented sugars dissolving the tooth enamel when tooth decay starts. But the advantage and mechanism of action by fluoride release are due to its ability to chemically reduce mineral loss by forming fluorapatite crystals, enabling effective remineralization and preventing tooth decay.
What Is the Pathophysiology of Demineralization?
Dental caries impact people of all ages and are universal in their occurrence, be it early childhood caries (ECC) in young infants, severe-early childhood caries (S-ECC), or dental caries of the milk tooth. In permanent dentition, six different dental carious lesions depending on the occurrence (class I to VI caries), recurrent caries, and root surface caries are common diseases.
These lesions initially occur only in the enamel. It further progresses to the dentin or the second tooth layer and consequently to the dental pulp or the root canals, causing hypersensitivity issues and dental pain.
The clinical expression of dental caries as a disease is by the pathophysiology of dental plaque bacterium metabolizing sugar into polymeric substances. These substances then stabilize their adherence to the enamel structure, eventually demineralizing the tooth's hard tissue. The products of sugar metabolism by the bacterium or oral microbial population that affects the tooth surface induce the development and continued progression of the lesions formed.
What Is the Rationale of Fluoridated Toothpaste?
The rationale of fluoride being most efficacious in toothpaste is sufficient evidence from clinical research indicating that regular toothbrushing with fluoridated pastes results in a relatively slower spread or extent of dental carious lesions. This can be attributed to the long-term impact of fluoride concentration baseline values (sufficient to combat dental caries) in the oral cavity even 10 hours after brushing with the fluoridated toothpaste.
Several randomized control studies and trials over the last two decades document that toothpaste containing at least 1000 to 5000 ppm of fluoride is recommended ideally for preventing caries initiation of demineralization of the tooth enamel. Fluoride is used past 5000 ppm to avoid root caries lesions. This is because dentin is more carious than the enamel region, and a higher concentration of fluoride in the toothpaste is needed to prevent demineralization.
Traditional research also shows that non fluoridated toothpaste is not ineffective compared to maintaining excellent periodontal health but certainly ineffective in contrast to fluoridated toothpaste in reducing the prevalence of dental caries. This is because a fluoridated toothpaste enhances active mineralization of tooth structure even in areas where the toothbrush does not reach or is partially inaccessible while brushing (such as in the gingival crevices of posterior molars or tilted molars).
Very low fluoridated toothpaste and less than 500 ppm are ineffective in caries control (especially if the diet is more cariogenic). Even if a biofilm from an unavailable tooth surface during brushing is left out, it is still enriched by the fluoride present in the toothpaste. This is why dental surgeons widely prefer fluoridated paste, as the non fluoridated paste cannot eliminate the plaque of an inaccessible area of the tooth nor affect it.
Is There a Need for Professional Fluoride Application?
Professional fluoride application is always beneficial to prevent future carious lesions in specific populations such as children and young adults, wherein the primary and mixed dentition are risk-prone to faster caries formation.
Professional fluoride applications, either in fluoride gels or varnishes, are indicated for all age groups depending on the individual risk factor for caries sequelae and progression. Especially in children, the risk factors and dietary lifestyle should be assessed thoroughly by school dental surgeons or the local dentist to establish routine fluoride application (neutral sodium fluoride or stannous fluoride or APF gels) i. e. either annually, semi-annually, or once every three months, depending on the material used and the child or young adult's caries risk.
Significant scientific evidence shows that the fluorapatite is incorporated into the lattice structure employing professional fluoride application and acts as a fluoride reservoir in the oral cavity, thus enabling remineralization. High-concentration fluoride gels range from 9000 ppm to 12300 ppm, while high concentrate fluoride varnish ranges up to 22500 ppm.
Community water fluoridation has been a tremendous preventive modality in the last decade. According to recent research, it is not shown to cause fluorosis (excess fluoride that causes whitish to brown streaks in enamel) in normal populations. The problem of fluorosis or extra fluoride concentration may be linked to only certain areas of developing countries. The dentist should recommend alternative remineralizing toothpaste for these individuals upon examination.
Conclusion:
Fluoridated toothpaste remains the most effective strategy to prevent dental caries. The accepted rationale, along with professional fluoride application and community water fluoridation, can significantly improve the remineralization of tooth surfaces.
