Higher Fluorosis Severity Makes Enamel Less Resistant to Demineralization

Abstract

Fluorotic teeth could either be more resistant or more susceptible to the caries process than sound ones due to their higher enamel fluoride concentration and higher porosity (subsurface hypomineralization), respectively; however, there is no consensus on this subject. In this study, a total of 49 human unerupted third molars presenting Thylstrup and Fejerskov (TF) fluorosis scores 0-4 were used. Two enamel slabs were obtained from each tooth. The rest of the tooth crown was powdered, and the enamel was separated from the dentine. In purified powdered enamel, the calcium (Ca), inorganic phosphate (P_i), and fluoride (F) concentrations were determined. The F concentration gradient throughout the enamel and in the enamel volume was determined in one slab. The other enamel slab was isolated with acid-resistant varnish, subjecting the exposed enamel surface half to a pH-cycling model to evaluate its demineralization resistance and to calculate the demineralization area. The nonexposed surface was used to determine the natural hypomineralization area found in fluorotic enamel and normalize the demineralization data. The hypomineralization and demineralization areas were assessed by cross-sectional microhardness. For statistical analyses, the data for TF1 and 2, and for TF3 and 4 were pooled. Concentrations of powered enamel Ca and Pi were not significantly different (p > 0.05) among groups TF0, TF1-2 and TF3-4, but a higher F concentration was found in fluorotic enamel (p < 0.05). Highly fluorotic teeth (TF3-4) presented a greater hypomineralization subsurface area and demonstrated lower demineralization resistance than sound enamel (p < 0.05). The findings suggest that a higher severity of fluorosis makes enamel less resistant to the caries process due to its greater subsurface mineral area exposed to demineralization and deeper acid diffusion through the enamel.

Clinical changes in the severity of dental fluorosis: a longitudinal evaluation

“…Its clinical appearance varies from white diffuse and irregular lines in mild cases to loss of structure and marked discoloration in the more severe forms [ 1 ]. Teeth with DF higher severity score show decreased resistance to demineralization, compared to sound enamel on lab studies or natural teeth [ 6 ].…”

Evaluation of enamel demineralization and fluorine uptake caused by gustatory stimulants of salivary secretion (GSSS) using Raman spectroscopy and proton induced gamma‐ray emission (PIGE)

“…From one individual to another, the age, the living location, or the amount of fluorine available during tooth formation are causes for fluorine concentration variation. Moreover, in the same individual, the type of tooth (canine, incisor, premolar or molar), the tooth surface (labial, distal, lingual or mesial), the tooth region (occlusal, middle, cervical), and the depth of measurement can present different fluorine concentrations …”

A Qualitative and Comprehensive Analysis of Caries Susceptibility for Dental Fluorosis Patients

“…When faced with a cariogenic challenge, it is the subsurface apatite crystals that are dissolved, consequently causing a subsurface lesion [ 14 ]. Accordingly, it can be reasonably concluded that a fluorotic tooth displaying higher clinical severity represents a wider mineral area to be dissolved by acids and the permeability of acid through enamel might be elevated [ 4 ]. In more clinically severe forms of DF post-eruptive damage happens, revealing less caries-resistant subsurface (see descriptions below).…”

“…This porous characteristic is demonstrated by clinical features ranging from enamel opacities, discoloration, or stains to structural defects (pits, cracks, and fissures) [ 1 , 2 ]. However, despite its intimate relationship with fluoride, which is widely recognized as “the cornerstone of dental caries reduction” [ 3 ], the enamel caries susceptibility of DF has remained ambiguous [ 4 ]. Epidemiological surveys have demonstrated contradictory conclusions.…”