Does Post-bleaching Fluoridation Affect the Further Demineralization of Bleached Enamel? An In Vitro Study

Hande Kemaloğlu; Hüseyin Tezel; Zeynep Ergücü


BMC Oral Health. 2014;14(113) 

In This Article


Bleaching has been accepted as one method of treating discolored teeth. Recently, novel in-office bleaching products that use high concentrations of hydrogen peroxide (HP) have made in-office treatments easier. However, the effects of these products on enamel are still an open issue and need to be clarified. When vital teeth are bleached, as a result of the direct contact between the bleaching agent and the outer enamel surface, the enamel surface of the tooth crown can be affected by high levels of HP in bleaching agents, causing structural and morphological changes. There are many studies on the reduction in microhardness as well as the loss of calcium from bleached enamel.[1–4] Furthermore, some changes in bleached enamel were described as slightly erosive defects promoted by the bleaching agent.[4–7]

The positive effect of highly concentrated fluoride products related to the inhibition of demineralization and erosion is well documented.[8] Different topical fluoride applications such as sodium fluoride (NaF), acidulated phosphate fluoride, and stannous fluoride are widely used in promoting enamel remineralization. However, unlike the commonly used agents, it has been suggested in the literature that titanium tetrafluoride (TiF4), may have a greater effect on enamel remineralization. Furthermore, the use of fluoride products after bleaching procedures has also been shown to be beneficial.[2,9,10] As topical fluoride is applied following bleaching, mineral loss is significantly reduced, microhardness is restored, and the resistance of enamel to demineralization is increased.[4,10,11]

Fluoride has been confirmed to remineralize lesions by increasing resistance to acid attack by forming a calcium fluoride layer to inhibit demineralization.[9] In addition, the formation of a glaze layer has been shown when enamel surfaces were treated with low pH TiF4.[12,13] However, there are no data available in the literature on the preventive effect of these applications on further demineralization. Thus, the aim of this present study was to examine the effects of two different post-bleaching fluoridation agents (NaF and TiF4) on the Ca2+ loss from enamel after an acidic challenge. The null hypotheses tested were: (1) no difference will be observed in Ca2+ release between the fluoridated and non-fluoridated groups of bleached enamel surfaces, after being subjected to acidic attack; thus, these fluoride agents will not affect the susceptibility of bleached enamel to further demineralization and (2) no differences in Ca2+ release will be noted between NaF- and TiF4-treated enamel surfaces after being subjected to further demineralization following bleaching with 38% HP.