The demin/remin cycle

Products help achieve caries balance in remineralization

Say this fast three times: demineralization, remineralization; demineralization, remineralization; demineralization, remineralization.

It kind of makes your eyes cross, doesn’t it? If you could reduce the science of dental hygiene to just a few main points, the cycle of demineralization/remineralization would surely be among them. During the last few years, we’ve seen a fundamental shift in the way we deal with the demin/remin cycle. We no longer have to “watch” it; we can influence it. And influencing it is at the core of another shift called minimally invasive (MI) dentistry.

MI dentistry, according to the World Congress of Minimally Invasive Dentistry, is nothing more or less than respect. MI, says the WCMID, respects the health of oral tissue by “preventing disease from occurring, or intercepting the disease process with minimal tissue loss.”1

One way to do this is with caries assessment by risk management (CAMBRA). CAMBRA is the treatment of dental caries as an infectious disease that is preventable and curable.² The first step in utilizing CAMBRA is a patient assessment form that collects data, organizes it, and categorizes the patient as being at high, medium, or low risk for caries. After the assessment, evaluations such as bacterial screening, pH testing, and measurement of saliva quality may be ordered.³ Diagnosis and treatment planning follow, then the patient is treated with minimal invasion of intact enamel and dentin in mind.

Those are the basics. Caries, the most common disease in the world, can be categorized by CAMBRA and managed with MI dentistry, an important component of which is directing the demineralization/re-mineralization cycle.

The cycle of demineralization and remineralization

Let’s start with that cycle. It’s called the caries balance. According to Featherstone,4 caries balance is determined by “the relative weight of the sums of pathological factors and protective factors.”

Think of the oral environment as a scale that must be continually balanced and rebalanced. When sugar, acid, and fermentable carbohydrates enter the mouth, the scale tips out of balance. Acid is metabolized, which decreases oral pH. When pH goes below 5.5, hydroxyapatite crystals in the enamel begin to break down. Calcium and phosphate exit the enamel, weakening it and eventually causing the chalky white spots of demineralization that may eventually become caries.

Remineralization can occur naturally when calcium and phosphorus reenter the enamel with the help of good-quality saliva, but we now know we can hurry that process along with a variety of products.

Fluoride was the first line of defense for many years, and it’s still an important component of remineralization. Topical fluoride forms a fluorapatite layer, which is stronger and more acid-resistant than the hydroxyapatite layer.⁵ A recent study compared the effects of fluoride gel and fluoride varnish on enamel erosion. The study concluded that fluoride varnishes interfere positively with the dissolution of dental enamel in the presence of acidic beverages. Fluoride gel showed the best protection level to extrinsic erosion with a lower cost.⁶ Another study looked at the effects that different concentrations of fluoride in toothpastes would have on remineralization. Toothpaste fluoride is most effective, the study concluded, at 5g/l.7

The effects of xylitol varnishes and solutions on enamel erosion have also been studied. Souza et al. concluded that a 10% xylitol solution “appears to be a good option to partially reduce enamel erosion.”8 Another study done in Japan concluded that xylitol can induce remineralization in deeper layers of enamel by facilitating Ca2+ movement and accessibility.⁹ Xylitol products, including gum, lozenges, candies, sugar substitutes, and stick-on dissolvable tablets, are becoming readily available to patients over-the-counter and on the Internet.

Casein phosphopeptide and amorphous calcium phosphate — found in products such as GC America’s MI Paste and MI Paste Plus (CPP-ACP), and Premier’s Enamel Pro varnish and prophy paste (ACP) — can also be good remineralization weapons for our arsenals. The International Journal of Paediatric Dentistry recently published a study done in China. Enamel surface microhardness was measured before demineralization, after demineralization, and 30 days after remineralization with CPP-ACP. The results showed CPP-ACP to be more effective in remineralizing early lesions than 500 ppm NaF. Recaldent, the product name for CPP-ACP technology, can be found in gum, toothpaste, and mouth rinses.10

Another product that promotes remineralization of teeth is calcium sodium phosphosilicate, known as NovaMin. NovaMin is a bioactive glass that delivers silica and ionic calcium, phosphorus, and sodium for bone and tooth mineralization. In the mouth, NovaMin releases sodium, calcium, and phosphate ions, which then interact with oral fluids and result in the formation of a crystalline hydroxycarbonate apatite (HCA) layer that is structurally and chemically similar to natural tooth mineral.11 The product is found in Nupro Sensodyne prophylaxis paste and in Nuvora’s Dentiva and Salese products, as well as Burt’s Bees Natural Toothpaste.12

A study of NovaMin’s efficacy in enamel remineralization found that, when added to a prescription-level fluoride dentifrice, NovaMin improved hardening of white-spot lesions.13

Though both Recaldent and NovaMin have been shown to be effective in remineralization, it should be noted that one study found no statistically significant differences in actual prevention of demineralization between teeth treated with NovaMin and Recaldent, and teeth not treated at all.14

Another component of MI dentistry is the concept of atraumatic restorative treatment (ART). ART can be defined as an alternative approach for controlling caries with minimal tooth loss in a vulnerable patient population. It can be especially useful in primary teeth. Think of homeless people, methamphetamine addicts, underserved children, and nursing home residents. With ART, a clinician excavates necrotic tooth tissue with hand instruments and applies a glass ionomer filling material. The procedure takes only a few minutes, and a compromised tooth in a compromised patient can be stabilized for some period of time.

A study completed this year in India looked at the survival rates of ART restorations in primary molars. At six months, the retention rate of ART restorations placed in a school setting was 82.2%. At 12 months, the retention rate was 77.77%.15 Two-year survival rates were studied in Kenya, and it was found that 31% of ART restorations were still in place in primary molars.16

In West Africa, ART restorations were evaluated after 48 months. Dental auxiliaries placed 117 class III ART restorations using glass ionomer material. After 48 months, 76 restorations were still in place, and 53 of them were classified as clinically acceptable.17

If you consider dentistry as it was practiced 20 years ago, dentistry as it is practiced today, and dentistry as it might be practiced 20 years in the future, it’s easy to see that we are moving away from the old models of “drill-and-fill” and “extension for prevention.” Our new model will be to preserve original tooth structure by using the principles of CAMBRA, scientific testing, and remineralization.

Cathy Hester Seckman, RDH, has written on dental topics for 26 years. She speaks on pediatric issues, and works clinically in a pediatric practice. She is also an indexer and a novelist.

References

1. www.wcmidentistry.com, accessed 7-1-11.
2. Young DA et al. “New directions in interorganizational collaboration in dentistry: The CAMBRA coalition model” J Dent Educ. 71(5): 595-600 2007.
3. Germack M “Why you need to attack caries differently” Dental Products Report 2009.
4. “The caries balance: the basis for caries management by risk assessment” Oral Health Prev Dent. 2004;2 Suppl 1;259-64.
5. Featherstone JD (2008). “Dental caries: a dynamic disease process.” Aust Dent J 53 (3): 286-91.
6. De Carvalho et al. “Energy dispersive X-ray spectrometry study of the protective effects of fluoride varnish and gel on enamel erosion.” Microsc Res Tech 2010 Nov 17 (epub ahead of print).
7. Liu HC et al. “Remineralization of artificial root caries by fluoride dentifrice on different fluoride concentration in vitro.” Shanghair Kou Qlang Yi Zue 2010 Dec;19(6):653-7.
8. Souza JG et al. “Effects of experimental xylitol varnishes and solutions on bovine enamel erosion in vitro.” J Oral Sci 2010;52(4):533-9.
9. Miake Y et al. “Remineralizaton effects of xylitol on demineralized enamel.” J Electron Microsc (Tokyo) 2003;52(5):471-6.
10. Zhang Q et al. “Remineralization effects of casein phosphopeptide-amorphous calcium phosphate crème on artificial early enamel lesions of primary teeth.” Int J Paediatr Dent 2011 June 1 (epub ahead of print).
11. http://adr.sagepub.com/content/21/1/35.full Accessed 8-1-11
12. http://en.wikipedia.org/wiki/NovaMin#Products_Containing_NovaMin. Accessed 7-13-11
13. http://adr.sagepub.com/content/21/1/35.full Accessed 8-1-11
14. Wang X et al. “Preventing erosion with novel agents.” J Dent. 2011 Feb;39(2):163-70.
15. Noor-Mohammed R, Basha S. “Survival of occlusal ART restorations in primary molars placed in school environment and hospital dental setup-one year follow-up study.” Med Oral Patol Oral Cir Bucal. 2011 Jul 15 (epub ahead of print).
16. Kemoli AM et al. “Two-year survival rates of proximal ART restorations in relation to glass ionomer cements and postrestoration meals consumed.” Pediatr Dent 2011 May-Jun;33(3):246-51.
17. Jordan RA et al. “Class III ART in adults living in West Africa – outcomes after 48 months.” Community Dent Oral Epidemiol. 2011 Apr;39(2):164-70.