In Dr. Franklin Garcia-Godoy and colleagues’ April JADA article, "Potential Inhibition of Demineralization In Vitro by Fluoride-Releasing Sealants" (JADA 2007;138[3]:502–6), differences in demineralization were attributed to the differences in leaching of fluoride from the materials. Their results agree with numerous other investigations that show that fluoride-treated enamel is more resistant to acid dissolution than enamel that has not been exposed to fluoride.
Reference is made to outer lesions and wall lesions, which are terms associated with secondary (recurrent) caries lesions. These two parts of secondary caries lesions were first described in the early 1970s based on in vitro–induced lesions. Subsequent studies, also using polarized light microscopy, have had difficulties demonstrating "wall lesions" associated with "natural" secondary caries lesions.
Toward the end of the article, the authors again refer to outer lesions and wall lesions, although the wall lesions are poorly documented; that is, they extrapolate the in vitro data to be valid for "natural" secondary caries. The authors go beyond what has been shown in their study by inferring that the leaching of fluoride from a dental material will have an effect on secondary caries.
The readers of JADA may be reminded about observations related to secondary caries and the effect of fluoride leaching from dental materials:
- – Clinically diagnosed secondary caries are localized defects at the cavosurface margin of restorations. The diagnosis is dubious, and some may be noncarious physical defects.
- – Crevices at the tooth/ restoration interface may result in bacteria in the crevice, but bacteria are normal habitants of the oral cavity and most of them are nonpathogenic.
- – Studies to characterize the composition of the content of crevices at tooth/restoration interfaces are lacking. The content is derived primarily from saliva and possibly from dentin tissue fluid. It is likely to be a proteinacious, pelliclelike material that will pick up dyes in vivo; hence, stained cracks in teeth and stained margins of tooth-colored restorations.
- – It has been repeatedly demonstrated that there is no relationship between the size of a crevice and the development of secondary caries.
- – "Microleakage" has not been demonstrated to play a role in the development of secondary caries in situ, but "macroleakage" may lead to secondary caries lesions.
- – One study on xerostomic patients with poor oral hygiene has demonstrated a slight positive effect of fluorides in the restorative material, provided no other topical fluoride was available.
- – True secondary caries lesions are the same as primary caries lesions adjacent to a restoration, and they likely will have benefits from fluorides.
- – Although demineralization is an important part of caries development, demineralization in vitro is different from "natural caries." The ecology and the dynamics of the dental plaque are lacking in vitro.
References to document the above statements are found in my October 2005 JADA article, "Clinical Diagnosis of Recurrent Caries."1
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