Introduction

Fluoride is naturally occurring in a variety of minerals and water sources. Its capacity to fortify tooth enamel—the teeth's outermost layer of protection—makes it important for dental health. Because enamel is mostly made of hydroxyapatite crystals, it can demineralize when it comes into contact with the acids that are created by bacterial plaque.¹ This demineralization process can result in tooth decay, a frequent oral health problem that, if left untreated, can cause discomfort, agony as well as the loss of teeth. 

To fully appreciate fluoride's significance in preventing tooth decay, one must understand its causes. Bacterial plaque is created when bacteria build up on tooth surfaces. It breaks down sugars and carbs in food to produce acids as byproducts leading to tooth decay.

Read on to learn the processes of tooth decay and how fluoride can help to prevent this.

Understanding tooth decay

The causes of decay occur in stages and are linked to several factors like poor oral hygiene and inadequate saliva production. The process can be seen in Figure 1.

Dental plaque formation

Dental plaque is a biofilm of microorganisms that develop on mucosal and dental surfaces within the mouth. Bacteria such as streptococci and lactobacilli (Figure 1) prefer to feed on sugars and carbohydrates from the food we eat. This rapid conversion of carbohydrates produces acidic byproducts that can erode tooth enamel over time, thus leading to the formation of cavities or caries.

Acid formation

Bacteria that metabolise sugars and carbohydrates produce lactic acid. This lowers the pH in the mouth creating acidic conditions that are favourable for specific bacteria that demineralised enamel.¹

Demineralisation

Demineralisation (Figure 2) is a process that leads to the gradual breakdown of hydroxyapatite crystals in enamel. Enamel is a tough substance in our body, found in the outer layer of the tooth and its structure is highly mineralised making it very resistant. However, the acid produced by plaque weakens enamel and makes it more susceptible to tooth decay. 

Tooth decay

As tooth decay worsens, the teeth tend to turn brown with white spots white spots may appear on teeth that have turned brown due to the continuous breakdown of the enamel. 

Figure 1. Process of plaque formation and tooth decay.¹

By understanding these various causes of tooth decay, individuals can take proactive measures to prevent cavities and maintain adequate oral hygiene.

Role of fluoride in dental health

Fluoride primarily works to control early dental cavities/caries in various ways. Fluoride is antimicrobial and anticarcinogenic and works via topical mechanisms which include:

• Inhibition of bacterial activity
• Promotion of enamel remineralisation (Figure 2)
• Stimulation of saliva production

Inhibition of Bacteria

Fluoride can inhibit the activity of oral bacteria by interfering with acid and plaque formation. Fluoride inhibits elonase activity, an essential enzyme in the bacterium, so prevents bacterial growth.¹ Additionally, fluoride acts to reduce the acid tolerance of bacteria by enhancing membrane permeabilities to protons¹

Promotion of remineralisation

Fluoride promotes the remineralisation of tooth enamel by bringing calcium and phosphate ions together. This is because the presence of fluoride in saliva speeds up crystal precipitation, leading to the formation of fluorapatite which is more resistant to caries.³ Thus strengthening the enamel and reversing early stages of tooth decay.

Figure 2. Illustration of the demineralisation and remineralisation process.²

Stimulation of saliva production

Saliva is essential for maintaining oral health, and fluoride has been shown to increase its production. Saliva helps wash away bacteria and food particles from the mouth, lowering the chance of tooth decay.¹

Fluoride is beneficial in preventing tooth decay because it can boost saliva production, limit bacterial activity, promote remineralisation, and impede enamel demineralisation. For this reason, fluoride is frequently added to drinking water, mouthwash, and toothpaste in many areas as a public health strategy to promote dental health.

Benefits and cons of fluoride

Forms of fluoride application

Fluoride Toothpaste

Fluoride is available and commonly used as part of daily oral hygiene routines. There are multiple types of fluoride-containing toothpastes. This can be sodium fluoride, sodium monofluorophosphate or stannous fluoride.⁶

Fluoridated water

Fluoridation is the dosing of water supplies to bring the fluoride level up to 1 mg per litre. This is a public health measure to reduce tooth decay levels.⁴

Fluoride treatments by Dentists

Dentists may apply fluoride products such as fluoride varnish. This can be applied to both baby and adult teeth by a dentist. Fluoride varnishing involves painting varnish, containing high levels of fluoride, onto the surface of the tooth to prevent decay and strengthen tooth enamel.

Fluoride mouth rinses, which contain 1350 ppm fluoride, can be prescribed for children and adults who already have tooth decay. This should be used in addition to brushing with toothpaste.⁴

Addressing fluoride concerns

Fluoride contamination has become a threat and a concern worldwide. Excess amounts of fluoride ions in drinking water can result in dental fluorosis, bone damage, osteoporosis and other issues.⁵ The concerns regarding the use of fluoride are primarily due to dental fluorosis and the acceptable levels of fluoride in drinking water and dental products. Although dental fluorosis is mainly a cosmetic issue, it can cause worry among parents. However, parents can supervise their children's toothbrushing practices and monitor their fluoride intake to avoid this minor condition. Health authorities strictly regulate the levels of fluoride in water and dental products to balance the benefits of cavity prevention with the risk of fluorosis.⁴ Numerous studies support the safety and effectiveness of fluoride in preventing tooth decay. Recommendations from dental professionals and health organisations help ensure the appropriate use of fluoride, resolve fluoride-related issues and promote rational decision-making.

Recommended dosage of fluoride

There is a variety of toothpaste containing various levels of fluoride as seen inTable 1. The amount of fluoride is measured in parts per million (ppm) and is found on the side of the tube. The most effective amount of fluoride contains 1350 to 1500 ppm.⁴

Table 1. Recommended dosage of fluoride toothpaste⁴

FAQ

What else can I do to prevent tooth decay?

In addition to taking fluoride, avoid drinking and eating foods that contain high sugars to prevent bacteria build up as such foods and drinks create a preferable environment for bacteria to accumulate and grow.

Summary

To summarise, fluoride is beneficial against oral bacteria to prevent tooth decay. Fluoride is available in forms such as water, varnish, toothpaste or rinses. Fluoride is important in the prevention of tooth decay by fortifying dental enamel, so it is more resistant to acid attacks by bacteria and the formation of plaque. Fluoride is essential in our daily lives and should be taken at the recommended doses to guarantee oral benefits.