Effect of fluoride application during radiotherapy on enamel demineralization

Abstract Radiation-related caries are one the most undesired reactions manifested during or after head and neck radiotherapy. Fluoride application is an important strategy to reduce demineralization and enhance remineralizaton. Objective: To evaluate the effect of the topical application of fluoride during irradiation on dental enamel demineralization. Material and Methods: Thirty molars were randomly divided into three groups: Non-irradiated (NI), Irradiated (I), Irradiated with fluoride (IF). Each group was subdivided according to the presence or absence of pH-cycling (n=5). In the irradiated groups, the teeth received 70 Gy. The enamel's chemical composition was measured using Fourier Transform Infrared Spectrometry (organic matrix/mineral ratio - M/M and relative carbonate content - RCC). Vickers microhardness (VHN) and elastic modulus (E) were evaluated at three depths (surface, middle and deep enamel). Scanning electron microscopy (SEM) was used to assess the enamel's morphology. Results: The FTIR analysis (M/M and RCC) showed significant differences for irradiation, pH-cycling and the interaction between factors (p<0.001). Without pH-cycling, IF had the lowest organic matrix/mineral ratio and relative carbonate content. With pH-cycling, the organic matrix/mineral ratio increased and the relative carbonate content decreased, except for IF. VHN was influenced only by pH-cycling (p<0.001), which generated higher VHN values. ANOVA detected significant differences in E for irradiation (p<0.001), pH-cycling (p<0.001) and for the interaction between irradiation and pH-cycling (p<0.001). Increased E was found for group I without pH-cycling. With pH-cycling, groups I and IF were similar, and showed higher values than NI. The SEM images showed no morphological changes without pH-cycling. With pH-cycling, fluoride helped to maintain the outer enamel's morphology. Conclusions: Fluoride reduced mineral loss and maintained the outer morphology of irradiated and cycled enamel. However, it was not as effective in preserving the mechanical properties of enamel. Radiotherapy altered the enamel's elastic modulus and its chemical composition.

Efeito da irradiação laser associada à aplicação tópica de fluoreto sobre o esmalte submetido à erosão e/ou abrasão / Effect of laser irradiation associated with topic application of fluoride on sound enamel submetted to erosion and/or abrasion

A aplicação do laser sobre o esmalte associada ou não a aplicação tópica de fluoreto têm demonstrado aumentar sua resistência à ação de ácidos. O presente estudo teve como objetivo avaliar o efeito da irradiação laser de alta potência associada à aplicação de fluoretos sobre o esmalte dentário submetido à erosão e/ou abrasão dentária. Para tal, 184 blocos de esmalte foram selecionados pela microdureza de superfície (SMH inicial) e foram divididos em 8 grupos com 23 espécimes cada (3 foram utilizados para realização da biópsia básica da superfície de esmalte dentário, 10 foram submetidos à erosão e os outros 10 à erosão associada à abrasão): G1- sem tratamento (controle); G2- tratamento com flúor fosfato acidulado (1,23% F) por 4 min; G3- verniz fluoretado; G4- irradiação com laser Nd:YAG (56,6 J/cm2); G5- aplicação de flúor fosfato acidulado e posterior irradiação com laser Nd:YAG (56,6 J/cm2); G6- aplicação de flúor fosfato acidulado e prévia irradiação com laser Nd:YAG (56,6 J/cm2); G7- aplicação de verniz fluoretado e posterior irradiação com laser Nd:YAG (56,6 J/cm2); G8- aplicação de verniz fluoretado e prévia irradiação com laser Nd:YAG (56,6 J/cm2). Após os tratamentos, os blocos submetidos à ciclagem erosiva sofreram 4 imersões diárias em bebida ácida com pH 2,6, 0,32 ppm F (Coca-Cola Company, Spal, Porto Real, RJ, Brasil), por 2 min, seguida pela imersão em solução remineralizadora por 2 h, durante 5 dias. Nos blocos submetidos à erosão associada à abrasão, uma vez ao dia após cada ciclo, os espécimes foram submetidos à abrasão com 40 ciclos de escovação simulada com força de 2,5 N. Os blocos de esmalte foram avaliados por meio da perfilometria. Os resultados foram submetidos à ANOVA a um (biopsia básica) e dois critérios (perfilometria) e Teste de Tukey (p<0,05). Todos os grupos de tratamento promoveram menor desgaste dentário em relação ao controle, sendo que entre eles, a irradiação laser promoveu o pior...

The laser application on enamel associated or not to the topic fluoride have been showed to increase the resistance to acid action. This study aimed to evaluate the effect of high intensity laser irradiation submitted to dental erosion and/or abrasion. Hence, 184 enamel samples were selected by surface microhardness (initial SMH) and then divided into 8 groups with 23 specimens each (3 were selected to routine biopsy of enamel surface, 10 submitted to erosion procedure and another 10 were submitted to erosion associated to abrasion): G1 without treatment (control group); G2 treated with acidic phosphate for 4 min (1.23% F); G3 fluoride varnish; G4 - irradiation with Nd:YAG laser (56.6 J/cm2) ; G5 - acidic phosphate fluoride with posterior irradiation with Nd:YAG laser (56.6 J/cm2) ; G6 application of acidic phosphate fluoride with previous irradiation of Nd:YAG laser (56,6 J/cm2); G7- application of fluoride varnish with posterior laser irradiation with Nd:YAG laser (56,6 J/cm2); G8- application of fluoride varnish with previous irradiation of Nd:YAG laser (56,6 J/cm2). After the treatments, the samples were submitted to erosive cycling with 4 diary immersions in acidic beverages with pH 2.6, 0.32 F ppm (Coca-Cola Company, Spal, Porto Real, RJ, Brasil) for 2 min followed by remineralized solution for 5 days. To groups submitted to erosive associated to abrasion, once a day after each cycling, the specimens were submitted to abrasion with 40 simulated brushing cycles with power of 2.5 N. The enamel samples were evaluated by profilemetry. The results were submitted to one way ( routine biopsy) and two way (profilometry) ANOVA and Tukey test (p < 0.05). All the groups demonstrated a wear dental decrease in relation to control group, and among them, the laser irradiation promoted the worst outcome (p < 0.05). The groups related to fluoride resulted in increase concentration of fluoride in the enamel...

Efeito da irradiação laser associada à aplicação tópica de fluoreto sobre o esmalte submetido à erosão e/ou abrasão / Effect of laser irradiation associated with topic application of fluoride on sound enamel submetted to erosion and/or abrasion

A aplicação do laser sobre o esmalte associada ou não a aplicação tópica de fluoreto têm demonstrado aumentar sua resistência à ação de ácidos. O presente estudo teve como objetivo avaliar o efeito da irradiação laser de alta potência associada à aplicação de fluoretos sobre o esmalte dentário submetido à erosão e/ou abrasão dentária. Para tal, 184 blocos de esmalte foram selecionados pela microdureza de superfície (SMH inicial) e foram divididos em 8 grupos com 23 espécimes cada (3 foram utilizados para realização da biópsia básica da superfície de esmalte dentário, 10 foram submetidos à erosão e os outros 10 à erosão associada à abrasão): G1- sem tratamento (controle); G2- tratamento com flúor fosfato acidulado (1,23% F) por 4 min; G3- verniz fluoretado; G4- irradiação com laser Nd:YAG (56,6 J/cm2); G5- aplicação de flúor fosfato acidulado e posterior irradiação com laser Nd:YAG (56,6 J/cm2); G6- aplicação de flúor fosfato acidulado e prévia irradiação com laser Nd:YAG (56,6 J/cm2); G7- aplicação de verniz fluoretado e posterior irradiação com laser Nd:YAG (56,6 J/cm2); G8- aplicação de verniz fluoretado e prévia irradiação com laser Nd:YAG (56,6 J/cm2). Após os tratamentos, os blocos submetidos à ciclagem erosiva sofreram 4 imersões diárias em bebida ácida com pH 2,6, 0,32 ppm F (Coca-Cola Company, Spal, Porto Real, RJ, Brasil), por 2 min, seguida pela imersão em solução remineralizadora por 2 h, durante 5 dias. Nos blocos submetidos à erosão associada à abrasão, uma vez ao dia após cada ciclo, os espécimes foram submetidos à abrasão com 40 ciclos de escovação simulada com força de 2,5 N. Os blocos de esmalte foram avaliados por meio da perfilometria. Os resultados foram submetidos à ANOVA a um (biopsia básica) e dois critérios (perfilometria) e Teste de Tukey (p<0,05). Todos os grupos de tratamento promoveram menor desgaste dentário em relação ao controle, sendo que entre eles, a irradiação laser promoveu o pior...

The laser application on enamel associated or not to the topic fluoride have been showed to increase the resistance to acid action. This study aimed to evaluate the effect of high intensity laser irradiation submitted to dental erosion and/or abrasion. Hence, 184 enamel samples were selected by surface microhardness (initial SMH) and then divided into 8 groups with 23 specimens each (3 were selected to routine biopsy of enamel surface, 10 submitted to erosion procedure and another 10 were submitted to erosion associated to abrasion): G1 without treatment (control group); G2 treated with acidic phosphate for 4 min (1.23% F); G3 fluoride varnish; G4 - irradiation with Nd:YAG laser (56.6 J/cm2) ; G5 - acidic phosphate fluoride with posterior irradiation with Nd:YAG laser (56.6 J/cm2) ; G6 application of acidic phosphate fluoride with previous irradiation of Nd:YAG laser (56,6 J/cm2); G7- application of fluoride varnish with posterior laser irradiation with Nd:YAG laser (56,6 J/cm2); G8- application of fluoride varnish with previous irradiation of Nd:YAG laser (56,6 J/cm2). After the treatments, the samples were submitted to erosive cycling with 4 diary immersions in acidic beverages with pH 2.6, 0.32 F ppm (Coca-Cola Company, Spal, Porto Real, RJ, Brasil) for 2 min followed by remineralized solution for 5 days. To groups submitted to erosive associated to abrasion, once a day after each cycling, the specimens were submitted to abrasion with 40 simulated brushing cycles with power of 2.5 N. The enamel samples were evaluated by profilemetry. The results were submitted to one way ( routine biopsy) and two way (profilometry) ANOVA and Tukey test (p < 0.05). All the groups demonstrated a wear dental decrease in relation to control group, and among them, the laser irradiation promoted the worst outcome (p < 0.05). The groups related to fluoride resulted in increase concentration of fluoride in the enamel...