Anti-erosive profile of an experimental 5% SnCl₂ varnish containing different concentrations of NaF

Abstract This in vitro study evaluated the anti-erosive effect of an experimental varnish containing 5% stannous chloride (SnCl₂) associated with different concentrations of NaF (NaF-free, 2.5% NaF, or 5.2% NaF) on bovine enamel and root dentin. One hundred samples were pre-eroded (0.3% citric acid, pH 2.6, 10 min) and randomized into five groups (n=10 for each substrate): Negative control - milli-Q water; NaF-free - Experimental varnish SnCl₂-free and NaF-free; 2.5 NaF - Experimental varnish 5% SnCl₂ associated with 2.5% NaF; 5.2 NaF: Experimental varnish 5% SnCl₂ associated with 5.2% NaF and positive control - Commercial varnish containing 5% NaF (Duraphat). After the varnishes were applied, the erosive and abrasive challenges were carried out for five days. Loss of tooth structure (TSL) was determined by optical profilometry, and the loss of calcium (ΔCa2+) using atomic absorption spectroscopy. Dentin analysis was also performed by SEM. A one-way ANOVA/Bonferroni test was performed to analyze the data (α=0.05). The experimental 2.5 NaF and 5.2 NaF groups showed greater effectiveness in preventing TSL when compared to the other groups (p <0.05), regardless of the substrate. In addition, these groups showed lower loss in Ca2+ content when compared to the other groups (p <0.05), for enamel and dentin. Dentin showed greater TSL and ΔCa2+ loss when compared to enamel in all treatments (p <0.05). The 5.2% and 2.5% NaF-containing experimental varnishes showed promising results in both, the prevention of TSL and the loss of Ca2+, regardless of the substrate studied.

Resumo Este estudo in vitro avaliou o efeito anti-erosivo de um verniz experimental contendo 5% de cloreto estanoso (SnCl₂) associado a diferentes concentrações de NaF (sem NaF, 2,5% NaF ou 5,2% NaF) sobre esmalte e dentina radicular bovinos. Cem amostras foram pré-erodidas (ácido cítrico 0,3%, pH 2,6, 10 min) e randomizadas em cinco grupos (n=10 para cada substrato): Controle negativo - água milli-Q; Sem NaF - Verniz experimental sem SnCl2 e sem NaF; 2,5 NaF - Verniz experimental 5% SnCl2 associado a 2,5% NaF; 5,2 NaF: Verniz experimental 5% SnCl2 associado a 5,2% NaF e controle positivo - Verniz comercial contendo 5% NaF (Duraphat). Após a aplicação dos vernizes, os desafios erosivos e abrasivos foram realizados por cinco dias. A perda de estrutura dentária (PED) foi determinada por perfilometria óptica e a perda de cálcio (ΔCa2+) por espectroscopia de absorção atômica. A análise da dentina também foi realizada por MEV. Um teste ANOVA/Bonferroni de uma via foi realizado para analisar os dados (α=0,05). Os grupos experimentais 2,5 NaF e 5,2 NaF apresentaram maior eficácia na prevenção de PED quando comparados aos demais grupos (p<0,05), independentemente do substrato. Além disso, esses grupos apresentaram menor perda no teor de Ca2+ quando comparados aos demais grupos (p<0,05), para esmalte e dentina. A dentina apresentou maior PED e de ΔCa2+ quando comparada ao esmalte em todos os tratamentos (p<0,05). Os vernizes experimentais contendo NaF 5,2% e 2,5% apresentaram resultados promissores tanto na prevenção de PED quanto na perda de Ca2+, independente do substrato estudado.

Evaluation of Dental Enamel Mass in Prolonged Supervised Dental Bleaching Protocol with Calcium-Containing Gel

ABSTRACT: The objective of this study was to determine the enamel mass variation after a prolonged bleaching treatment using a calcium-containing 4% hydrogen peroxide gel Twenty sound bovine incisors were randomly assigned to two groups (n=10) stored in G1) distilled water and G2) artificial saliva. An electronic analytic scale (.000 grams measurements) was used to determine the enamel mass variation before and after the bleaching procedures at the following evaluation times: T0) before the bleaching procedures; T1) 14 days of treatment, as instructed by the manufacturer; T2) 21 days of treatment, 50 % beyond what is instructed by the manufacturer; and T3) 28 days of treatment, 100 % beyond what is instructed by the manufacturer. The highest mean was observed at T2/G2 (0.3259 g) and the lowest at T2/G1 (0.3265 g). The specimens stored in distilled water (G1) showed 6 % mass reduction when T0 (0.3277 g) was compared to T3 (0.3277 g). On the other hand, the specimens stored in artificial saliva exhibited a significant mass increase of 19 % when T0 (0.3521 g) was compared to T3 (0.3528 g). Prolonged bleaching therapy using 4 % hydrogen peroxide with calcium resulted in a massive reduction when water was used as a storage medium. When the specimens were stored in artificial saliva, an increase in mass was observed, probably due to the mineralizing properties of the artificial saliva.

RESUMEN: El objetivo de este estudio fue determinar la variación de la masa del esmalte después de un tratamiento de blanqueamiento prolongado utilizando calcio conteniendo un gel de peróxido de hidrógeno al 4 %. Veinte incisivos bovinos intactos fueron asignados aleatoriamente a dos grupos (n-10) almacenados en G1 - agua destilada y G2- saliva artificial. Se utilizó una escala analítica electrónica (.000 gramos) para determinar la variación de la masa de esmalte antes y después de los procedimientos de blanqueamiento en los siguientes tiempos de evaluación: T0) antes de los procedimientos blanqueadores; T1) 14 días de tratamiento, según las instrucciones del fabricante; T2) 21 días de tratamiento, 50 % más allá del tiempo indicado por el fabricante; y T3) 28 días de tratamiento, 100 % más allá del tiempo indicado por el fabricante. La media más alta se observó en T2/G2 (0,3259 g) y la más baja en T2/G1 (0,3265 g). Los especímenes almacenados en agua destilada (G1) mostraron una reducción de masa del 6 % cuando se comparó T0 (0,3277 g) con T3 (0,3277 g). Por otro lado, los dientes almacenados en saliva artificial mostraron un aumento significativo de masa del 19 % cuando se comparó T0 (0,3521 g) con T3 (0,3528 g). La terapia de blanqueamiemto prolongado con calcio conteniendo un gel de peróxido de hidrógeno al 4 % condujo a una reducción masiva cuando se utilizó agua como medio de almacenamiento, mientras que los dientes almacenados en saliva artificial mostraron un aumento en la masa, probablemente debido a las propiedades remineralizadoras de la saliva artificial.

Is prolonged bleaching more harmful to dental enamel than daily dietary and hygienic oral habits?

Abstract The ultrastructural and mechanical properties of enamel surface were evaluated after prolonged bleaching treatments with 10% carbamide peroxide in the presence or absence of orange juice (erosive challenge) and toothbrushing (abrasive challenge). In total, 145 incisor bovine teeth were used in this study. Twenty-five samples were prepared for the ultrastructural evaluations, and 120 samples were prepared for microhardness and roughness tests. These 120 samples were divided into eight experimental groups (n = 15): G1- artificial saliva; G2- abrasion; G3- erosion; G4- dental bleaching; G5- erosion + abrasion; G6- bleaching + abrasion; G7- bleaching + erosion; and G8- bleaching + erosion + abrasion. All groups were tested at T0 (before treatment), T1 (14 days), T2 (21 days), and T3 (28 days). Two-way analysis of variance for repeated measures and the post hoc Sidak tests (p ≤ 0.05) were used. The roughness evaluation demonstrated an increase in damage for all experimental groups with an increase in the time period. For microhardness, the groups exposed to artificial saliva (AS) and abrasive challenge did not show any differences at any time points, while the other groups showed a decrease in microhardness from T0 to T3. Ultrastructural evaluation showed different surface alterations in response to the treatments. Despite prolonged bleaching periods, the procedure caused lesser enamel surface alterations than exposure to orange juice alone or in combination with brushing.

Influence of Different Time Intervals among the in-Office Bleaching Sessions on the Tooth Enamel Mass Variation / Influência do Intervalo de Tempo Entre as Sessões de Clareamento Profissional na Variação de Massa do Esmalte Dental

This study evaluated the effect of different time intervals between tooth bleaching sessions on the variation of tooth enamel mass, using a 35% hydrogen peroxide (HP35) gel. Twenty bovine incisor teeth were collected and cross-sectioned twice, leaving only the middle coronal portion. The dentin layer was removed, leaving only the buccal dental enamel. The samples were randomly divided into 2 groups (n = 10): G1 (with a 7-day time interval between each bleaching session), and G2 (with a 2-day time interval between each bleaching session). Three bleaching sessions were performed for each group. Each specimen's mass was measured using an electronic analytical scale, first at the beginning of the experiments (T0), and then immediately after each bleaching intervention (T1, T2 and T3, respectively). All samples were stored in artificial saliva and kept in a biological chamber during the time of the study. The data analysis was performed using ANOVA for the related samples (p = 0.05). The results showed a reduction in the enamel mass values in G2 after the 3rd session when comparing to enamel mass values presented at the beginning of the study. On the other hand, G1 presented an increase in the mass values at the end of the third session, and these intragroup differences were statistically significant (p <0.001). It was concluded that bleaching treatment with 7-day intervals between sessions leads to no tooth enamel mass loss, whereas the reduced 2­day time interval between sessions caused a significant tooth enamel mass loss. (AU)

Este estudo avaliou a influência de diferentes intervalos de tempo entre as sessões de clareamento com peróxido de hidrogênio a 35% (PH35) sobre a variação de massa do esmalte dental. Foram utilizados 20 dentes incisivos bovinos hígidos, seccionados em duas porções transversais, com a camada de dentina vestibular toda removida, restando apenas o esmalte dental vestibular. As amostras foram distribuídas em 2 grupos (n=10): G1 - intervalo de tempo de 7 dias entre as sessões de clareamento, e G2 - Intervalo de 2 dias entre as sessões de clareamento. Foram realizadas 3 aplicações de gel clareador em cada grupo. A pesagem dos espécimes foi realizada antes do início do tratamento clareador e ao final de cada intervenção clareadora, em uma balança analítica eletrônica. Os espécimes foram armazenados em saliva artificial, e mantidos em estufa biológica. Os dados foram submetidos à ANOVA para amostras relacionadas (p=0.05). O G2 apresentou uma redução nos valores de massa do esmalte quando comparados os tempos antes do clareamento (T0 - 0.1650g) e após a 3° sessão (T3 - 0.1643g). Entretanto, o G1 apresentou um aumento nos valores de massa ao término da terceira sessão (T0 - 0.1615g e T3 - 0.1624g), sendo essas diferenças intragrupos estatisticamente significantes (p<0.001). Foi possível concluir que no clareamento com intervalo de 7 dias entre as sessões não houve perda de massa do esmalte dental, ao passo que quando reduzido o intervalo entre as sessões para 2 dias, uma perda significativa de massa foi observada. (AU)

Influence of Prolonged Tooth Bleaching on Enamel Mass Variation / Influencia del Blanqueo Dental Prolongado en la Variación de Masa del Esmalte Dental

ABSTRACT: The objective evaluate was the influence of prolonged tooth bleaching with 10 % carbamide peroxide (10CP) on tooth enamel mass variation. Ten healthy bovine incisor teeth were divided (n = 5) into G1 - storage in distilled water and G2 - storage in artificial saliva. The samples were weighed in an electronic analytical balance at the following times: T0 - before application of the bleaching gel, T1 - after 14 days of bleaching (the time recommended by the manufacturer), T2 - after 21 days of bleaching (50 % increase in the time recommended by the manufacturer), and T3 - after 28 days of bleaching (100 % increase in the time recommended by the manufacturer). The data were subjected to ANOVA for related samples (p = 0.05). The highest mean was observed in G2 (0.5982 g) and the lowest mean was observed in G1 (0.3074 g) at T2 and T3, respectively. Significant differences were observed between the groups at all times. Overall, 10CP caused variation in the enamel mass after a 100 % increase in the use time recommended by the manufacturer, with a decrease in mass when distilled water was used as the storage medium and an increase when artificial saliva was used.

RESUMEN: El objetivo fue investigar la influencia del blanqueamiento dental prolongado con peróxido de carbamida al 10 % (10CP) sobre la variación de masa del esmalte dental. Las muestras se dividieron en dos grupos: G1, diez dientes sanos de los incisivos bovinos (n = 5) en agua destilada, y G2, almacenamiento en saliva artificial. Las muestras se midieron en una escala analítica electrónica de precisión en los siguientes tiempos: T0-antes de la aplicación del gel blanqueador, T1-después de 14 días de blanqueo (el tiempo recomendado por el fabricante), T2-después de 21 días de blanqueo (aumento de 50 % en el tiempo recomendado por el fabricante), y T3-después de 28 días de blanqueo (aumento de 100 % en el tiempo recomendado por el fabricante). Los datos se presentaron al ANOVA para las muestras relacionadas (P = 0,5). La media más alta se observó en G2 (0,5982 g) y la media más baja se observó en G1 (0,3074 g) en T2 y T3, respectivamente. Se observaron diferencias significativas entre los grupos en todo momento. En general, la 10 CP causó variación en la masa del esmalte después de un aumento de 100 % en el tiempo de uso recomendado por el fabricante, con una disminución en la masa cuando el agua destilada se utilizó como medio de almacenamiento y aumentó cuando se usó saliva artificial.