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.

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.

AmF/NaF/SnCl2 solution reduces in situ enamel erosion - profilometry and cross-sectional nanoindentation analysis

Abstract This in situ study aimed to investigate the effect of a tin-containing fluoride solution in preventing enamel erosion. Also, its effects on the partly demineralized zone were assessed for the first time. Thirteen volunteers participated in this 2-phase study, wearing removable intra-oral appliances containing four sterilized bovine enamel slabs, for 8 days, where 2 treatment protocols were tested using samples in replicas (n = 13): CO - no treatment (negative control) and FL - AmF/NaF/SnCl2 solution (500 ppm F-, 800 ppm Sn2+, pH = 4.5). Samples were daily exposed to an erosive challenge (0.65% citric acid, pH 3.6, 4 min, 2x/day). In the 2nd phase, volunteers switched to the other treatment protocol. Samples were evaluated for surface loss using a profilometer (n = 13) and a cross-sectional nanohardness (CSNH) test (n = 13) was carried out in order to determine how deep the partly demineralized zone reaches below the erosive lesion. The data were statistically analyzed by two-way ANOVA. Erosive challenges lead to smaller enamel surface loss (p < 0.001) in the FL group when compared to group CO. Data from CSNH showed that there was no significant difference in demineralized enamel zone underneath erosion lesions between the groups. An amorphous layer could be observed on the surface of enamel treated with tin-containing solution alone. Under the experimental conditions of this in situ study, it can be concluded that AmF/NaF/SnCl2 solution prevents enamel surface loss but does not change the hardness of the partly demineralized zone near-surface enamel.

Adhesion to eroded dentin submitted to different surface treatments / Adesão a dentina erodida submetida a diferentes tratamentos de superfícies

Objective: This in vitro study measured the microshear bond strength (μSBS) of a composite resin to sound and artificially eroded dentin, submitted to surface treatment with diamond bur (DB) or Er,Cr:YSGG laser (L). Material and Methods: Bovine radicular dentin samples were randomly divided into six groups (n = 11): G1- positive control (sound dentin), G2- negative control (eroded dentin), G3-eroded dentin treated with Er,Cr:YSGG laser at 1.5 W, G4-eroded dentin treated with Er,Cr:YSGG laser at 2.0 W, G5-eroded dentin treated with Er,Cr:YSGG laser at 2.5 W and G6-eroded dentin treated with diamond bur. Erosive cycling was performed by immersion in 0.05M citric acid (pH 2.3; 10 min; 6x/day) and in remineralizing solution (pH 7.0, 1 h, between acid attacks), for 5 days. Three composite resin cylinders were bonded to the samples with etchand-rinse adhesive system and after 24 h storage in distilled/deionized water (37 ºC), samples were submitted to microshear bond strength test and mean values (MPa) were analyzed by one-way ANOVA and Tukey tests (α = 0.05). Results: G1 (19.9 ± 7.6A) presented the highest μSBS mean followed by G6 (12.2 ± 3.8B), which showed no statistically significant difference compared with the other groups, except from G4. The lowest μSBS value was found for G4 (7.1±1.5C), which did not differ statistically from G2 (7.5 ± 1.8B,C), G3 (8.4 ± 1.8B,C) and G5 (8.6 ± 3.2B,C). Analysis of the fracture pattern revealed a higher incidence of adhesive fractures for all experimental groups. Conclusion: The results indicate none of the surface treatments (diamond bur and Er,Cr:YSGG laser irradiation at the parameters used in this in vitro study), associated with the etch-and-rinse adhesive system, did not enhance composite resin bonding to eroded dentin...

Objetivo: O presente estudo in vitro visou avaliar a resistência de união (RU) de uma resina composta à dentina hígida e dentina erodida artificialmente, submetidas a diferentes tratamentos de superfície: ponta diamantada (DB) ou Er, Cr: YSGG (L) em diferentes parâmetros. Material e Métodos: Amostras de dentina radicular bovina foram aleatoriamente divididas em seis grupos (n =11): G1- controle positivo (dentina hígida sem tratamento); G2 – controle negativo (dentina erodida sem tratamento); G3 - dentina erodida condicionada com laser de Er,Cr:YSGG (L) em 1,5W; G4 – dentina erodida condicionada com Er,Cr:YSGG em 2,0 W; G5 - dentina erodida condicionada com Er,Cr:YSGG em 2,5 W e G6 - dentina erodida tratada com ponta diamantada. A formação da lesão de erosão foi realizada através de 5 dias de ciclagem por imersão alternada em solução desmineralizadora (ácido cítrico 0,05 M; pH 2,3; 10 min; 6x/dia) e em solução remineralizadora (pH 7,0; 1 h, entre os ataques de ácido). Três cilindros de resina composta foram confeccionados na superficie plana das amostras com o auxílio de um sistema adesivo tipo “condicione e lave”. Após o armazenamento em água destilada/ deionizada por 24 h a 37 ºC, os corpos de prova foram submetidos ao ensaio de microcisalhamento e a media dos valores de RU (MPa) obtidos foram analisados pelo teste ANOVA e teste de Tukey (α = 0,05). Resultados: Os resultados mostraram que G1 (19,9 ± 7,6A) apresentou os maiores valores de RU seguido do grupo G6 (12,2 ± 3,8B), que não apresentou diferença estatisticamente significativa em comparação com os outros grupos, com exceção do G4. O menor valor de RU foi encontrado no grupo G4 (7,1 ± 1,5C), que não diferiu estatisticamente do G2 (7,5 ± 1,8B,C), G3 (8,4 ± 1,8B,C) e G5 (8,6 ± 3,2B,C). A análise do padrão de fratura revelou uma maior incidência de fraturas adesivas para todos os grupos experimentais...

Conservative esthetic treatment of a discoloured calcified permanent tooth: five-year clinical evaluation / Tratamento conservador estético de um dente permanente calcificado e escurecido: cinco anos de acompanhamento clínico

Objective: Pulp calcification can compromise tooth color and negatively affect esthetics. Definitive treatment for discolored anterior teeth with calcification is usually provided by endodontic treatment with the use of internal and external bleaching agents, as necessary. This article presents the conservative management of a vital tooth with an obliterated pulp chamber that led to changes in tooth color. The benefits and limitations of the use of in-office and home supervised bleaching techniques are discussed

Objetivo: Uma calcificação pulpar pode comprometer a cor dos dentes e afetar negativamente a estética dental. O tratamento de escolha para um dente anterior escurecido e com calcificação pulpar é geralmente o tratamento endodôntico seguido de clareamento interno e externo, se necessário. Esse artigo relata um caso clínico de um tratamento conservador de um dente vital com câmera pulpar obliterada que ocasionou alteração de cor do elemento dental. Os benefícios e as limitações do uso das diferentes técnicas de clareamento dental utilizadas também foram discutidos.

Avaliação in vitro do potencial do laser de CO2, associado ou não a produtos fluoretados, em inibir erosão em esmalte dental humano / In vitro evaluation of the potential of CO2 laser associated or not to fluorides in inhibiting human enamel erosion

Considerando a eficácia limitada do flúor na proteção dos tecidos duros dentais contra a erosão, o objetivo do presente estudo foi investigar o potencial do laser de gás carbônico (CO2) (10,6 m), associado ou não a produtos fluoretados, na inibição da erosão de esmalte dental. Amostras de esmalte dental humano foram obtidas e divididas aleatoriamente em 8 grupos (n = 11): G1: controle (sem tratamento), G2: gel de Flúor Fosfato Acidulado (FFA), G3: gel de fluoreto de sódio (AmF/NaF), G4: solução de fluoreto estanhoso (AmF/SnF2), G5: laser de CO2 (0,3 J/cm2, 15 s, 226 Hz), G6: laser de CO2 + gel de FFA, G7: laser de CO2 + gel de AmF/NaF e G8: laser de CO2 + solução de AmF/SnF2. Após os tratamentos de superfície, as amostras foram imersas em ácido cítrico a 1% (pH 4,0, 3 minutos). Antes dos tratamentos de superfície e após o desafio ácido, a microdureza de superfície foi mensurada (0,49 N, 20 segundos) e os dados foram analisados estatisticamente através do teste ANOVA com subseqüentes comparações entre pares (p < 0,05). Os resultados mostraram que o grupo G3 (403,5 ± 25,0) apresentou a maior média de microdureza Knoop após o desafio ácido, seguido pelos grupos G2 (396,6 ± 45,0) e G6 (392,8 ± 24,9), sem diferença estatística entre eles. Dentre os grupos tratados com produtos fluoretados, o grupo G4 (305,5 ± 17,7) resultou em microdureza significativamente mais baixa que o G3 (403,5 ± 25,0) e o G2 (396,6 ± 45,0), os quais foram estatisticamente semelhantes entre si. Dentre os grupos tratados com laser, os grupos G5 (341,1 ± 23,8), G7 (374,9 ± 42,1) e G8 (328,6 ± 26,9) apresentaram valores de dureza estatisticamente semelhantes entre si. Dentro dos limites do presente estudo in vitro, pôde-se concluir que o tratamento com gel de AmF/NaF e gel de FFA (com ou sem irradiação prévia com o laser de CO2) mostrou potencial para controlar a progressão da erosão no esmalte dental humano.

Considering the limited effectiveness of fluoride in protecting dental hard tissues against erosion, the aim of the present study was to investigate the potential of the CO2 laser (10.6 m) associated to fluoride agents in inhibiting human enamel erosion. Human enamel samples were obtained and randomly divided into 8 groups (n = 11): G1: control (no treatment), G2: APF gel, G3: AmF/NaF gel, G4: AmF/SnF2 solution, G5: CO2 laser (0.3 J/cm2, 15 s, 226 Hz), G6: CO2 laser + APF gel, G7: CO2 laser + AmF/NaF gel and G8: CO2 laser + AmF/SnF2 solution. After surface treatment, samples were immersed in 1% citric acid (pH 4.0, 3 min). Knoop Surface microhardness (SMH) (0.49 N, 20 s) was measured before surface treatments and after surface softening. The data were statistically analyzed by ANOVA model with subsequent pairwise comparisons (p < 0,05). Group G3 (403.5 ± 25.0) presented the highest SMH means after softening, followed by Groups G2 (396.6 ± 45.0) and G6 (392.8 ± 24.9) with no statistically significant difference between them. Between the fluoride-treated groups, G4 (305.5 ± 17.7) resulted in significantly low SMH mean than G3 (403.5 ± 25.0) and G2 (396.6 ± 45.0), which were statistically similar to each other. Between the laser-treated groups, G5 (341.1 ± 23.8), G7 (374.9 ± 42.1) and G8 (328.6 ± 26.9) presented SMH means statistically similar to each other. Within the limits of the present in vitro study, AmF/NaF and APF application (with or without previous CO2 laser irradiation) have shown a potential to control erosion progression in human dental enamel.