Strategies for Remineralization

Dental professionals must understand the dynamics of caries in order to effectively educate their patients and provide oral health education tailored to each individual. Caries is caused by the interaction of fermentable carbohydrates and biofilm with the tooth surface. Bacteria, specifically Streptococcus mutans and Lactobacillus species, meta­bolize the dietary carbohydrates and produce acid that lowers plaque pH. Low pH causes calcium and phosphate ions to leach out of tooth enamel, which is a crystalline matrix made primarily of calcium hydroxyapatite.^1,2 When intervals of low salivary pH are prolonged, demineralization begins. A substantial number of mineral ions can be lost from the hydroxyapatite matrix without destroying its structural integrity. However, patients with areas of demineralization may experience temperature sensitivity or pain, even though a caries lesion has not yet formed.³

Remineralization, on the other hand, is the natural reparative process that restores mineral ions to the tooth structure. Remineralization relies on calcium and phosphate ions to repopulate the enamel matrix by precipitation as pH increases.^1,2 Saliva plays a significant role in remineralization because it contains both calcium and phosphate, which replenish the minerals lost due to acidic exposures when pH is high enough.

Salivary pH is easy to measure and is often reported in studies, but the dynamics of demineralization and remineralization occur at the tooth surface, which is continually coated by a protein-rich salivary pellicle or dental plaque. Typical saliva has a pH ranging from 6.8 to 7.4, with enamel demineralization occurring at pH levels below 5.5. Salivary acidity increases when food or drinks with low pH, such as soft drinks (pH of 2.7 to 3.5), coffee (pH of 2.4 to 3.3), sports drinks (pH of 2.3 to 4.4), wine (pH of 2.3 to 3.8), and beer (pH of 4.0 to 5.0) are consumed.⁴ Over time, drinking these beverages can cause acid-induced erosion. Additionally, patients who eat healthy diets filled with fruits and vegetables, such as apples, oranges, grapefruit, and tomatoes, also experience acidic oral environments, as these foods have pH levels ranging from 2.8 to 4.0.4 Dental professionals need to educate patients on the potential negative effects of eating a diet composed primarily of acidic foods, in addition to the more commonly discussed effects of avoiding sugary and acidic drinks. Because demineralization occurs when the tooth undergoes an acidic challenge, reducing the frequency of acid exposure will greatly decrease the potential for demineralization. Educating patients on the harmful oral effects of between-meal snacking is important, because fewer snacks mean the teeth are exposed to fewer acidic attacks. Swishing with water, especially fluoridated water, can help wash away or dilute sugar before it is metabolized by bacteria. Also, chewing sugar-free gum can help decrease the acid levels by increasing salivary flow.

THERAPEUTIC OPTIONS

Many strategies are available to slow or stop caries progression by remineralizing the tooth surface, but deciding which is right for each patient can be challenging. Patients at high caries risk; who consume diets high in carbohydrates; who have poor oral hygiene, dentinal hypersensitivity, or xerostomia; and/or who are undergoing orthodontic treatment may benefit from using products that enhance remineralization.

Fluoride has been the gold standard for strengthening tooth structure for years.¹ It has antimicrobial properties that inhibit cariogenic bacteria and help create an acid-resistant tooth structure. Fluoride inhibits demineralization by penetrating the tooth surface, adsorbing onto hydroxyapatite crystals and thus preventing dissolution of the tooth minerals. It enhances remineralization by attracting calcium ions.¹ Consuming fluoridated water and using over-the-counter fluoride toothpastes reduce caries by maintaining a low concentration of salivary fluoride.⁵ Toothpastes containing calcium and phosphate, in addition to fluoride, may enhance remineralization. Prescription toothpastes containing 5,000 ppm fluoride (1.1% sodium fluoride) may be appropriate for at-risk patients. Mouthrinses containing .02% to .05% sodium fluoride may help reduce caries risk when used daily.6 Fluoride varnish (5% sodium fluoride) application is an in-office option that supports remineralization of the tooth surface.

Amorphous calcium phosphate (ACP) is a combination of soluble salts of calcium and phosphorous. It releases calcium and phosphate ions to remineralize tooth structure. ACP may reduce dentinal hypersensitivity, restore enamel luster, and enhance fluoride delivery. ACP is found in toothpaste, chewing gum, fluoride varnish and gel, prophy paste, sealants, desensitizing products, and whitening systems.^7,8

Casein phosphopeptide (CPP) is a milk protein that stabilizes ACP. This combined product, CCP–ACP (Recaldent), can penetrate and remineralize enamel. CCP–ACP needs an acidic exposure to release the calcium and phosphate ions. It may be effective in reducing enamel subsurface lesions.⁹ Recaldent can be found in pastes, fluoride varnish, and chewing gum.⁸

Calcium sodium phosphosilicate (NovaMin) is a synthetic material comprising calcium, sodium, phosphorus, and silica. It supports the creation of a natural crystalline hydroxycarbonate apatite layer, which is similar to natural tooth structure. In the presence of water or saliva, NovaMin releases sodium ions that increase pH. This initiates the release of calcium and phosphate, supporting remineralization.¹⁰ Novamin is found in toothpaste, prophy paste, desensitizing products, and air polishing powder.⁸

Tri-calcium phosphate (TCP) works with fluoride and can potentially remineralize and strengthen enamel to a greater extent than fluoride alone. When TCP is used in toothpaste, it creates a protective barrier around calcium ions, stabilizing them in the presence of fluoride ions. When TCP contacts saliva, it causes the protective barrier to dissolve and release calcium, phosphate, and fluoride ions.¹¹ TCP is available in prescription fluoride toothpaste and fluoride varnish.⁸

CONCLUSION

Maintaining an oral environment that helps prevent demineralization while promoting remineralization should be a goal for every patient, especially those prone to caries. Dental professionals can best serve their patients by reviewing the evidence available on remineralization technologies to determine which strategy may be most effective for individual patient needs.

References

1. Goldstep F. Dental remineralization: simplified. Available at: oralhealthgroup.com/features/dental-remineralization-simplified. Accessed April 19, 2016.
2. Featherstone JDB. Dental caries: a dynamic disease process. Aust Dent J. 2008;53:286–291.
3. Higham S. Caries process and prevention strategies: demineralization/remineralization. Available at: dentalcare.com/en-US/dental-education/continuing-education/ce372/ce372.aspx. Accessed April 19, 2016.
4. Cooper B. Protecting your healthy patients. Dimensions of Dental Hygiene. 2008;6(4):38–39.
5. ten Cate JM. Contemporary perspective on the use of fluoride products incaries prevention. Br Dent J. 2013;214:161–167.
6. Aminabadi NA, Balaei E, Pouralibaba F. The effect of 0.2% sodium fluoridemouthwash in prevention of dental caries according to the DMFT index. J Dent Res Dent Clin Dent Prospects. 2007;1:71–76.
7. Dorozhkin SV. Amorphous calcium (ortho) phosphates. Acta Biomater.2010;6:4457–4475.
8. Shah MA. Remineralize with calcium-based therapies. Dimensions of DentalHygiene. 2013;11(3):30–35.
9. Cai F, Shen P, Walker GD, Reynolds C, Yuan Y, Reynolds EC. Remineralization ofenamel subsurface lesions by chewing gum with added calcium. J Dent.2009;37:763–768.
10. Burwell AK, Litkowski LJ, Greenspan DC. Calcium sodium phosphosilicate(NovaMin): remineralization potential. Adv Dent Res. 2009;21:35–39.
11. Karlinsey RL, Mackey AC, Walker ER, Frederick KE. Preparation,characterization, and in vitro efficacy of an acid-modified-TCP material for dental hard-tissue remineralization. Acta Biomater. 2010;6:969–978.

From Dimensions of Dental Hygiene. May 2016;14(05):33–34.