The role of fluoride and chlorhexidine in preserving hardness and mineralization of enamel and cementum after gamma irradiation

Abstract

The purpose of this study was to evaluate the effect of 0.05% sodium fluoride and 0.12% chlorhexidine mouthwashes on the micro-hardness of tooth enamel and cementum that was exposed to therapeutic doses of gamma radiation. Sixty extracted human teeth were divided into two groups, one was irradiated, the other was not irradiated. The two groups were further subdivided into three subgroups, which were each treated either with 0.05% sodium fluoride or with 0.12% chlorhexidine; the third subgroup served as a control. After demineralization-remineralization cycling, teeth from the irradiated groups showed a significantly lower micro-hardness when compared to those from the non-irradiated groups. Both in the irradiated and non-irradiated groups, teeth from the control subgroups showed a significantly lower micro-hardness, as compared to teeth treated with sodium fluoride and chlorhexidine. For non-irradiated enamel samples, those treated with chlorhexidine showed a significantly less micro-hardness compared to those treated with sodium fluoride. In contrast, irradiated enamel showed no significant difference in micro-hardness, whatever treatment (chlorhexidine or sodium fluoride) was applied. For cementum, treatment with chlorhexidine resulted in a significantly lower micro-hardness compared to sodium fluoride, both for the irradiated and non-irradiated groups. It is concluded that gamma irradiation with therapeutic doses typically used for head and neck carcinoma treatment has a direct effect in reducing micro-hardness of tooth enamel and cementum. Mouthwash protocols including, for example, application of 0.05% sodium fluoride or 0.12% chlorhexidine three times per day for 6 weeks, can protect enamel and cementum against the reduction in hardness and demineralization caused by gamma irradiation. Sodium fluoride offers more protection compared to chlorhexidine.

Direct radiation-induced effects on dental hard tissue

“…It should be encouraged to use a soft toothbrush and floss or an interproximal brush to effectively remove dental plaque especially plaque attached at cervical areas. Due to the ability of fluoride ion to combine with apatite forming fluorhydroxyapatite [Ca 10 (PO 4 ) 6 (OH) 2-2x F 2x ], which is harder and less susceptible to dissolution, the use of fluoride becomes an ideal preventive strategy to promote remineralization and inhibit demineralization of tooth surfaces subjected to acids [33]. Daily use of high-concentrated fluoride products such as fluoride mouthwash and sodium fluoride gel was recommended during and after radiotherapy [34].…”

Effect of fluoride application during radiotherapy on enamel demineralization

“… 28 In the same way, previous studies have noted the importance of fluoride in the protection of these high-risk patients from caries in combination with good oral hygiene. 7 , 11 , 29 , 31 Kielbassa, et al 7 (1997) also stated that neutral or nearly neutral fluoride-containing gels or solutions should preferably be used.…”

Effects of different anti-caries agents on microhardness and superficial microstructure of irradiated permanent dentin: an in vitro study

“…The teeth were extracted for orthodontic reasons and none of them had any caries, restorations, defects or enamel hypoplastic. The teeth were thoroughly washed and ultrasonically scaled to remove plaque and calculus, and polished with rubber prophylaxis cup at a low-speed handpiece with a mixture of non-fluoridated oil-free pumice and water, then stored in physiological saline solution at a temperature of 4 °C (DW-25 W322, China) and used not more than 3 months post-extraction [20].…”