An Update on Demineralization/Remineralization

Mark E. Jensen, MS, DDS, PhD; Robert V. Faller, BS

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Enamel lesions are categorized according to where they are located. Smooth surface lesions occur on the buccal, lingual, and interproximal surfaces. Pit and fissure lesions occur in enamel pits or on occlusal fissures.

Primary and permanent teeth are affected in the same manner.

We can imagine the concepts of demineralization and remineralization to be a relatively new science. Actually we have had data around for a number of years to support the concept; we simply did not know how to interpret it. This study from Backer Dirks, for example, was done in 1966 prior to the extensive use of fluorides. In this study, 71 white spot lesions in 8-year olds were tracked for 7 years. All frank lesions were restored. At the end of the 7 years, the results demonstrated:

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Early white-spot lesion on the buccal surface of a right mandibular first permanent molar. White spot lesion on a left mandibular first permanent molar that has been partially remineralized and is stable without activity.

Mandibular left second premolar that has a buccal surface cavitation that cannot be remineralized and requires restoration. Note the additional distal surface caries that is visible upon preparation.

Along these same lines of observation, we more recently have begun to consider the entire caries process and approach the disease differently than in the past. We have long known caries is a complex biological process which involves an infectious agent (acid-forming bacteria), the host or patient, and the diet (fermentable carbohydrates). If the diet is balanced in such a way that the host protective factors (saliva) and fluoride can overcome the bacterial acid challenge, no net demineralization occurs. Increased frequency of foods that are acidogenic can tip this balance in the direction of net demineralization. A human, intraoral, demineralization/remineralization model was used to evaluate various between-meal snack foods. The study demonstrated that certain foods can cause net remineralization while "acidogenic" foods can cause demineralization.9 Duggal et al.10 used a slightly different human model to examine the frequency of carbohydrate consumption with and without fluoride toothpaste. When a fluoride free toothpaste was used and carbohydrate frequency exceeded 3 times per day, significant demineralization occurred. When subjects used a fluoride-containing toothpaste, net demineralization was only seen when carbohydrate consumption exceeded 10-times/day. This study emphasizes the need for use of a fluoride toothpaste by all patients to help balance, prevent, and reverse the caries process on a daily basis. Hicks et al.11-13 have provided a three-part series on the biological factors in the caries process with respect to demineralization and remineralization and also emphasize the role of low levels of fluoride on a daily basis.

In this example a 15-year old male had his orthodontic brackets removed and came directly to the general dentist's office presenting as shown below. This illustrates an imbalance in the demineralization/remineralization process to the extent of developing many frank cavitated lesions which cannot be remineralized. Is there a need for understanding the caries process here and preventing demineralization? Could the lesions have been recognized at an early stage and been reversed through remineralization?

(Case and photo credit to:  Dr. Neil Millikin)

Root Surface Caries

What about root caries?


We know the initial phase requires recession of the gingival margin so the root surface is exposed and at risk for caries. The tissue may be normal but recessed for a variety of reasons—abrasion (e.g., toothbrushing), aging, or periodontal conditions. This provides a tooth surface that has previously not been at risk.

Phase II of root caries is similar to that of coronal caries; the process typically begins apical to the cemento-enamel junction, presenting a few clinical symptoms.

There appears to be a healthy intact layer of cementum, which quickly dissolves. It is important to note enamel is approximately 88% mineral (by volume) while dentin is only about 45% mineral (by volume). So you can imagine the enhanced demineralization potential of the root surface relative to the enamel surface..

The question that faced researchers for a long time was, "Can a root surface remineralize since it is only approximately 45% mineral (by volume) to begin with?" The answer is absolutely . . . in fact it has been documented the root surface can remineralize to a higher mineral percent than it was initially. (One study: 67% more remineralization vs. placebo.)

With respect to root caries, Leake14 examined 807 references in an evidence-based approach. The accuracy of diagnostic systems is unknown but color of the lesion had little validity. The use of "softness" to define active lesions has been validated with the presence of microbes in the lesion. It has been suggested: "For patients aged thirty and older, the prevalence of root caries is roughly 20 to 22 percent less than a person's age. Severity reaches over one lesion by age fifty, two lesions by age seventy, and just over three lesions for those seventy-five and older. About 8 percent (odds of 1:11) of the population would be expected to acquire one or more new root caries lesions in one year." Consistent support for the use of fluorides in the remineralization of root caries was found.

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