Tipping the balance toward dental remineralization

Dental caries is a complex, multifactorial process that is caused by the progression of demineralization and remineralization. Although dental caries is preventable, it remains the most common chronic disease in children and is a worldwide epidemic, second only to the common cold.¹

Oral equilibrium

In the oral environment, there is a physiological equilibrium between demineralization and remineralization. Lesion progression or reversal depends upon the steadiness between the pathological factors that lead to demineralization (such as cariogenic bacteria, fermentable carbohydrates, and salivary dysfunction) and protective factors that tip the balance toward remineralization (such as antibacterial agents and sufficient saliva). As acids from cariogenic bacteria increase, the balance veers toward demineralization and net mineral loss, eventually leading to dental caries.²

Since our goal is caries prevention, factors in the oral cavity must be favorable for remineralization. These include, but are not limited to, adequate secretion of saliva and limiting frequency of sucrose consumption. Sticky foods are more harmful than nonsticky foods because they remain on the teeth. Good oral hygiene (i.e., brushing morning and night and interdental cleaning daily), in addition to regular professional hygiene appointments, is necessary to prevent dental caries. The scientific evidence recommends key techniques and topical agents for the remineralization process.

Defining demineralization

The process of demineralization and caries formation begins when bacteria convert dietary carbohydrates (especially sucrose) into acids through glycolysis. Streptococcus mutans and lactobacillus are the primary microorganisms that contribute to this process. Acids released by the microorganisms lower the pH of the biofilm to 5.5 (critical pH) allowing minerals to be lost from the enamel. At this pH, saliva and plaque are no longer saturated with calcium and phosphate, and this allows hydroxyapatite (HAP) to dissolve. Carious lesions develop in the subsurface due to the nature of the lesion’s surface. Crystals at the tooth surface are more resistant to demineralization, leaving subsurface crystals more susceptible to undersaturation conditions as hydrogen ions diffuse from the plaque. The surface layer has better conditions for saturation because of access to ions coming from the body of the lesion, plaque, and saliva, and is also covered by the salivary pellicle, which acts as a diffusion barrier that slows the outward diffusion of ions. If the demineralization process is not linear, however, continued cavitation eventually occurs.²

Encouraging remineralization

Remineralization involves the replacement of lost minerals in hard dental tissues that can stop, slow, or even reverse the caries process. The remineralization process is a natural repair mechanism that occurs under neutral pH conditions (7.0). The buffering capacity of saliva plays a critical role in helping restore the neutral pH at the tooth surface. Usually, between meals, the pH is higher than the critical pH, demineralization is arrested, and calcium and phosphate mineral ions are redeposited within the carious lesion. This process forms HAP crystals, which are larger and more resistant to the acid attacks of demineralization.

Saliva is the primary component in caries prevention as it neutralizes acids formed by plaque bacteria. Saliva naturally contains the necessary calcium and phosphate ions for preventing demineralization and allowing remineralization to occur. Many systemic diseases and medications contribute to hyposalivation, or xerostomia, that disrupt the balance between demineralization and remineralization. Natural remineralization is often insufficient for many white spot lesions when saliva is compromised. The recommendation of nutritional counseling and the use of topical agents are important.³

Fluoride treatment—the gold standard in caries prevention—is a valuable technique that enhances the remineralization process when calcium and phosphate ions recombine to form a strong crystal. When applied in low concentrations, fluoride increases the rate of growth and the size of enamel crystals. The accelerated rebuilding of the enamel crystals within the demineralized carious lesion initiates the remineralization that can reverse the progression of dental caries.²

There is a serious need for remineralization technologies and topical agents that can complement fluoride in products. Combining fluoride with calcium and phosphate makes enamel more resistant to acid demineralization than its previous state. This results in a reversal of the caries process, creating an enamel surface that is more resistant to dental caries.¹ Scientific research on this promising combination is evolving and will continue for many years to come. Prevention of dental caries is ideal, and effective communication and goal-setting in caries-reducing techniques will lead to positive patient experiences and a reduction in dental caries.

Specific regenerative dental medicaments can self-assemble into a three-dimensional biomatrix formed from naturally occurring amino acids. This matrix exhibits a high affinity for HAP, which allows crystallization and crystal growth of calcium phosphate. The matrix also serves as a crystallization nucleus for new HAP crystals and, thus, as a template for new enamel.⁴

One regenerative paste on the market today contains a casein phosphopeptide-amorphous calcium phosphate complex, naturally derived from milk, that releases calcium and phosphate ions to prevent caries by remineralization. When the paste is applied to the teeth, it binds with existing bacteria, plaque, and connective tissue to release calcium and phosphate that support the remineralization process.¹ Products containing regenerative therapies also buffer acids produced by plaque and bacteria, protect and rebuild the surface of the tooth, and decrease tooth hypersensitivity.

Conclusion

Dental caries is an infectious, transmissible bacterial disease. The use of regenerative therapies is recommended to slow or stop the multifactorial disease process of demineralization and dental caries before more extensive treatment becomes necessary.

Muddy flooding and sinkholes: Understanding the difference between caries and erosive tooth wear

REFERENCES

Dai Z, Liu M, Ma Y, et al. Effects of fluoride and calcium phosphate materials on remineralization of mild and severe white spot lesions. Biomed Res Int. 2019;2019:1271523. doi:10.1155/2019/1271523
Roberts MW, Hempton TJ. The dynamic process of demineralization and remineralization. Dimens Dent Hyg. July 9, 2009. https://dimensionsofdentalhygiene.com/article/the-dynamic-process-of-demineralization-and-remineralization/
Dowd FJ. Saliva and dental caries. Dent Clin North Am. 1999;43:579-597.
Schlee M, Schad T, Koch JH, Cattin PC, Rathe F. Clinical performance of self-assembling peptide P11-4 in the treatment of initial proximal carious lesions: a practice-based case series. J Investig Clin Dent. 2018;9(1):10.1111/jicd.12286. doi: 10.1111/jicd.12286

A native of North Dakota, Allison Dooley, MHS, ADT, RDH, has been a dental provider for 27 years. She was a member of the groundbreaking first cohort in Minnesota to receive the master of health sciences advanced dental practitioner degree in 2011. With a passion for her work in clinical dentistry, she enjoys creating smiles and educating her patients. She currently holds a staff position at Minnesota Community Care in St. Paul.

Nick Coller, MA, received his master’s in French and German from St. Catherine’s College, Oxford. He worked for 10 years in marketing, communication, and business strategy before moving into dentistry. A qualified senior hygienist in Germany, he earned a diploma in dental hygiene and therapy and a Tutor’s Award from King’s College Hospital. Coller is a passionate oral health educator and author, regularly contributing to the UK dental press and practicing in central and southwest London.