Effect of CO2 laser combined with AmF/NaF/SnCl2 solution on the prevention of human and bovine enamel erosion

Abstract: This in vitro study evaluated the potential of CO2 laser (10.6 μm) combined with a stannous/fluoride-containing solution for preventing erosion in human/bovine enamel. Forty-eight samples of each substrate were randomly allocated to four groups (n = 12): W - distilled water; E - AmF/NaF/SnCl2 solution; L - CO2 laser; and LE - CO2 laser+AmF/NaF/SnCl2 solution. After surface treatments, samples were submitted to a 5-day erosive challenge, alternating immersions in 0.5% citric acid (2 minutes, 6x/day) and in artificial saliva. Optical profilometry (μm) and scanning electron microscopy (SEM) were used to determine surface loss and surface morphology, respectively. Data were statistically analyzed by two-way ANOVA and Tukey's tests (p < 0.05). For human enamel, tissue loss was lower in group L (12.37 ± 4.46) than in group W (16.45 ± 2.76), and higher than in the groups treated with AmF/NaF/SnCl2 solution (E-5.44 ± 2.37; LE-5.55 ± 2.31). In group L, SEM images reveled a disorganized surface but fewer projections than in group W and LE showed fewer irregularities than W, E, and L. For bovine enamel, tissue loss in group L (13.90 ± 3.50) did not differ from that in group W (14.10 ± 2.98), and was higher than losses in groups E (5.70 ± 2.12) and LE (8.12 ± 2.56), which were statistically similar to each other. Groups W and L had similar aspects of demineralization, whereas groups E and LE showed homogenous surfaces. Surface-treated samples had no changes in their surfaces. CO2 laser was able to slightly prevent surface loss only on human enamel surface, but did not enhance the AmF/NaF/SnCl2 effect on the prevention of enamel erosion.

Bond strength of composite resin containing biomaterial S-PRG to eroded dentin

To evaluate the bond strength of composite resin containing or not biomaterial (S-PRG) to sound/eroded dentine. Methods: Occlusal dentin of 30 human molars (n=15) had half of its surface kept uneroded, while on the other half an erosive lesion was produced by cycling in citric acid (pH 2.3) and supersaturated solution (pH 7.0). On both eroded (ED) and non-eroded (SD) substrates, two restorative systems (containing or not S-PRG) were tested. Composite resin cylinders were built and, after storage in water (24h), were submitted to bond strength test. The analysis of the fracture pattern was performed under an optical microscope (40x). The obtained values of bond strength (MPa) were submitted to ANOVA (two factors) and Tukey multiple comparisons tests (p<0.05). Results: According to the results, there was difference between substrates (<0.001) and restorative materials (p=0.002) evaluated. For the microtensile bond strength, the values obtained were: SDNB (47.6±12.2 MPa), SDWB (34.1±15.8 MPa), EDNB (31.1±8.3 MPa) and EDWB (15.5±13.6 MPa), revealing a statistically significant difference in the evaluated substrates and restorative materials. Conclusion: Bond strength of eroded substrate is inferior to the sound substrate and the restorative system containing S-PRG biomaterial influences negatively the results of bonding to sound/eroded dentin (AU)

Titanium Tetrafluoride (TiF4) in the Treatment of Dental Erosion / Tetrafluoreto de Titânio (TiF4) no Tratamento da Erosão Dental

Dental erosion is a multifactorial pathology that leads to dental substrate loss caused by its exposure to acids of non-bacterial origin. The process begins with a superficial demineralization of enamel, which, when continuously exposed to erosive solutions, can even lead to dentin exposure, causing aesthetic/functional problems to patients, besides increasing the chances of dentin hypersensitivity. Fluoride products, when applied onto dental surface, form a protective physical barrier, which also acts as F ions reservoir. However, against recurrent erosive challenges, this protection has limited effectiveness. Current literature has already proven the capacity of compounds containing polyvalent metal cations associated with fluorides, including titanium tetrafluoride (TiF4), to form more acid-resistant layers. The ability of the titanium ion to bind simultaneously to F ions and dental tissue allow the formation of a diffusion barrier on the tooth surface, known as glaze, which may protect it against acid demineralization. However, it is still necessary to establish an ideal clinical protocol involving the definition of factors capable of determining the success of the treatment, such as concentration, pH, excipient and form/period of application, as well as frequency for reapplication. The present critical review aims to provide a brief overview of TiF4's mechanisms of action and discuss the factors that may improve its protection capacity against dental erosion. (AU)

A erosão dental é uma patologia multifatorial que leva a uma perda de substrato dental causada pela sua exposição a ácidos de origem nãobacteriana. O processo se inicia com uma desmineralização superficial do esmalte, que, quando da continua exposição a soluções erosivas, pode levar a exposição do esmalte, causando problemas estéticos/funcionais aos pacientes, além de aumentar a chance de hipersensibilidade dentinária. Os produtos fluoretados, quando aplicados sobre a superfície dental, formam uma barreira física de proteção, que também pode agir como reservatório de íons F. Entretanto, frente a recorrentes desafios erosivos, esta proteção tem efetividade limitada. A literatura recente já demonstrou a capacidade de compostos contendo cátions metálicos polivalentes associados a fluoretos, incluindo o tetrafluoreto de titânio (TiF4), para formar camadas mais ácido-resistentes. A capacidade do íon titânio de se ligar simultaneamente aos íons F e ao tecido dental permite a formação de uma barreira de difusão na superfície dental, conhecida como glaze, que a protege contra desmineralização ácida. Entretanto, ainda é necessário estabelecer um protocolo clínico ideal envolvendo a definição de fatores capazes de determinar o sucesso do tratamento, como concentração, pH, veículo e forma/tempo de aplicação, além da frequência para reaplicação. A presente revisão crítica tem como objetivo proporcionar uma breve visão geral dos mecanismos de ação do TiF4 e discutir os fatores que podem melhorar sua capacidade protetora contra a erosão dental. (AU)

The In Situ Effect of Titanium Tetrafluoride Gel on Erosion/Abrasion Progression in Human Dentin

Abstract Erosion incidence is increasing and its control is still a challenge in clinical practice. This study evaluated 4% TiF4-gel effects on eroded human dentin subjected to in situ erosive/abrasive episodes. Seventy-two previously eroded dentin slabs (0.05 M citric acid, pH 2.3, 20 min) were allocated to 6 groups (n=12) according to the treatment to be performed during the in situ phase and number of erosive/abrasive cycles, as follows: 4% TiF4-gel applied once (TiF41), twice (TiF42) or three times (TiF43) followed by 1, 2 and 3 erosive/abrasive cycles, respectively. Gel was applied before the beginning of the next cycle. Control groups were subjected to 1 (C1), 2 (C2) and 3 (C3) erosive/abrasive cycles only. A seventh group (n=12) comprised in vitro uneroded samples (UN) subjected to 3 erosive/abrasive cycles. Each cycle corresponded to 2 days of erosive (citric acid 0.5%, pH 2.6, 6x/day) and abrasive (electric toothbrush, 10 s/sample, 1 x/day) challenges. Samples were evaluated under profilometry and environmental scanning electron microscopy (ESEM). Atomic force microscopy images (AFM) were also made (n=3). Repeated measures 2-way ANOVA and Tukey test (p<0.001) showed that TiF42, which did not differ from TiF41 and TiF43, revealed a significant reduction in surface loss compared to all control groups. TiF41 and TiF43 showed no significant difference from C1, but both groups demonstrated significantly smaller surface loss than C2 and C3. ESEM and AFM micrographs suggested alterations on treated surfaces compared to samples from control groups, showing reduced diameters of dentinal tubules lumens. Therefore, TiF4 was able to reduce the progression of erosive/abrasive lesions.

Resumo A incidência da erosão tem aumentado e o seu controle ainda é um desafio na prática clínica. Este estudo avaliou os efeitos do gel de TiF4 a 4% sobre a dentina humana erodida submetida a episódios erosivos/abrasivos in situ. Setenta e dois fragmentos de dentina previamente erodida (ácido cítrico 0,05 M, pH 2,3, 20 min) foram distribuídas em 6 grupos (n=12) de acordo com o tratamento a ser realizado durante a fase in situ e o número de ciclos erosivos/abrasivos, como descrito a seguir: gel de TiF4 a 4% aplicado uma (TiF41), duas (TiF42) ou três vezes (TiF43) seguido de 1, 2 e 3 ciclos erosivos/abrasivos, respectivamente. As aplicações dos géis foram realizadas antes do início do ciclo erosivo seguinte. Grupos controle foram submetidos a 1 (C1), 2 (C2) e 3 (C3) ciclos erosivos/abrasivos apenas. Um sétimo grupo (n=12) compreendia amostras sem erosão in vitro (UN) submetidas a 3 ciclos erosivos/abrasivos. Cada ciclo correspondia a 2 dias de desafios erosivos (ácido cítrico a 0,5%, pH 2,6, 6x/dia) e abrasivos (escova de dentes elétrica, 10 s/amostra, 1x/dia). As amostras foram avaliadas em perfilômetro e Microscopia Eletrônica de Varredura Ambiental (MEV). Imagens de microscopia de força atômica (AFM) também foram capturadas (n=3). ANOVA a 2-fatores para medidas repetidas e o teste de Tukey (p<0,001) demonstraram que TiF42, que não diferiu do TiF41 e TiF43, revelou redução significativa na perda de superfície quando comparado a todos os grupos controle. TiF41 e TiF43 não apresentaram diferença estatisticamente significativa em relação ao C1, mas ambos os grupos demonstraram perda de superfície significativamente menor que C2 e C3. Micrografias de MEV e AFM sugeriram alterações nas superfícies tratadas quando comparadas a amostras dos grupos controle, apresentando redução no diâmetro das luzes dos túbulos dentinários. Portanto, o TiF4 foi capaz de reduzir a progressão das lesões erosivas/abrasivas.

Efeito do gel de TiF4 no controle da progressão da lesão de erosão em dentina humana estudo in situ / Effect of TiF4 gel in the control of the progression of erosion in human dentin an in situ study

Com o aumento na prevalência das lesões de erosão, medidas preventivas e de controle das mesmas vêm sendo propostas. Dentre elas, encontram-se os produtos fluoretados e, mais recentemente, os compostos contendo cátions metálicos polivalentes, como o tetrafluoreto de titânio (TiF4). Este estudo in situ visou avaliar os efeitos do gel de TiF4 na inibição da progressão da erosão em dentina humana erodida e abrasionada. Para tanto, foram obtidas oitenta e quatro amostras de dentina (3 x 3 x 1 mm) a partir de terceiros molares humanos hígidos. Setenta e duas amostras foram erodidas in vitro previamente a etapa in situ e divididas aleatoriamente em 6 grupos (n=12) de acordo com o tratamento e com o número de ciclos erosivos/abrasivos a serem executados durante a etapa in situ. Os grupos controle foram submetidos a apenas 1 (C1), 2 (C2) e 3 (C3) ciclos erosivos/abrasivos. Já os grupos experimentais receberam 1 (TiF4 1), 2 (TiF4 2) e 3 (TiF4 3) aplicações de gel de TiF4 (4%) seguidos de 1, 2 e 3 ciclos erosivos/abrasivos, respectivamente. Um sétimo grupo controle (n=12) foi incluído, sendo que amostras sem erosão in vitro foram submetidas a 3 ciclos erosivos/abrasivos. Cada ciclo erosivo/abrasivo correspondeu a 2 dias de desafios erosivos (ácido cítrico 0,5%, pH 2,6, 6x/dia) e abrasivos (1x/dia). Para realização da etapa in situ, as amostras foram posicionadas em dispositivos intra-orais removíveis utilizados por 12 voluntários. Os espécimes foram avaliados em perfilometria (n=12), microscopia eletrônica de varredura ambiental (MEV ambiental) (n=12) e microscopia de força atômica (AFM) (n=3) para avaliar as alterações causadas pelo fluoreto sobre a superfície da dentina. A ANOVA a dois critérios para medidas repetidas mostrou que o desgaste superficial foi afetado pelos tratamentos avaliados (p<0,001).

O teste de Tukey demonstrou que o grupo TiF4 2, que não diferiu dos grupos TiF4 1 e TiF4 3, apresentou redução significativa no desgaste quando comparado aos grupos C1, C2, C3 e controle sem erosão in vitro. Os grupos TiF4 1 e TiF4 3 não revelaram diferença significativa em relação ao grupo C1, porém ambos os grupos de tratamento demonstraram desgaste significativamente menor que C2 e C3. Os maiores desgastes foram verificados para C3 e controle sem erosão in vitro. As micrografias obtidas em MEV ambiental e AFM sugeriram a manutenção do glaze sobre a superfície da dentina tratada com o gel de TiF4, mesmo após os desafios ácidos. A superfície passou a apresentar um aspecto mais liso que as amostras dos grupos controles, com redução dos diâmetros dos lúmens dos túbulos dentinários, justificando o efeito protetor do TiF4. Portanto, o TiF4 demonstrou potencial em reduzir a progressão das lesões de erosão in situ, independente do número de aplicações avaliado.

With the increase in the prevalence of erosion lesions, preventive and control measures for them have been proposed. Among them are the fluoride products and, more recently, compounds containing polyvalent metal ions such as titanium tetrafluoride (TiF4). This in situ study aimed to evaluate the effects of the TiF4 gel on the erosion progression inhibition in human eroded and abraded dentin. For this purpose, eighty-four dentin samples (3 x 3 x 1 mm) were prepared from undamaged human third molars. Seventy-two samples of previously eroded dentin in vitro were allocated into 6 groups (n=12) according to the treatment to be received during the in situ phase and the number of erosive/abrasive cycles. Control groups were subjected to 1 (C1), 2 (C2) and 3 (C3) erosive/abrasive cycles only. Experimental groups had TiF4 gel (4%) applied once (TiF41), twice (TiF42) or three times (TiF43) followed by 1, 2 and 3 erosive/abrasive cycles, respectively. A seventh group (n=12) comprised in vitro uneroded samples that were subjected to 3 erosive/abrasive cycles. Each cycle corresponded to 2 days of erosive (citric acid 0.5%, pH 2,6, 6x/day) and abrasive (1x/day) challenges. To perform the in situ stage, the samples were placed in removable intra-oral devices used by 12 volunteers Specimens were evaluated in profilometry (n=12), environmental scanning electron microscopy (ESEM) (n=12) and atomic force microscopy (AFM) (n=3) to evaluate the changes caused by fluoride on the surface of the dentin.

The two-factor ANOVA for repeated measures showed that, after profilometric analysis, the surface loss was affected by the treatments evaluated (p<0.001). Tukeys test showed that TiF4 2 group, which did not differ from TiF4 1 and TiF4 3 groups showed a significant reduction in surface loss compared to C1, C2, C3 and in vitro-uneroded control. The TiF4 1 and TiF4 3 groups showed no significant difference from C1, but both treatment groups demonstrated significantly smaller surface loss than C2 and C3. The greatest losses were observed for C3 and in vitro-uneroded control. The micrographs by ESEM and AFM suggested the maintenance of the glaze on the dentin surface treated with the TiF4 gel, even after acid challenge. The surface started to show a smoother appearance than samples from control groups, with reduced diameters of the dentinal tubules lumens, explaining the protective effect of TiF4. Therefore, the TiF4 demonstrated potential to reduce the progression of erosion lesions, regardless of the number of applications evaluated.