Dentine microhardness after different methods for detection and removal of carious dentine tissue

There are several methods for identifying carious dentinal tissue aiming to avoid removal of healthy dentinal tissue. OBJECTIVES: The purpose of this study was to test different methods for the detection of carious dentinal tissue regarding the amount of carious tissue removed and the remaining dentin microhardness after caries removal. MATERIAL AND METHODS: The dentin surfaces of 20 bovine teeth were exposed and half of the surface was protected with nail polish. Cariogenic challenge was performed by immersion in a demineralizing solution for 14 days. After transverse cross-section of the crown, the specimens were divided into four groups (n=10), according to the method used to identify and remove the carious tissue: "Papacárie", Caries-detector dye, DIAGNOdent and Tactile method. After caries removal, the cross-sectional surface was included in acrylic resin and polished. In a microhardness tester, the removed dentin thickness and the Vickers microhardness of the following regions were evaluated: remaining dentin after caries removal and superficial and deep healthy dentin. RESULTS: ANOVA and Tukey's test (α=0.05) were performed, except for DIAGNOdent, which did not detect the presence of caries. Results for removed dentin thickness were: "Papacárie" (424.7±105.0; a), Caries-detector dye (370.5±78.3; ab), Tactile method (322.8±51.5; bc). Results for the remaining dentin microhardness were: "Papacárie" (42.2±10.5; bc), Caries-detector dye (44.6±11.8; abc), Tactile method (24.3±9.0; d). CONCLUSIONS: DIAGNOdent did not detect the presence of carious tissue; Tactile method and "Papacárie" resulted in the least and the most dentinal thickness removal, respectively; Tactile method differed significantly from "Papacárie" and Caries-detector dye in terms of the remaining dentin microhardness, and Tactile method was the one which presented the lowest microhardness values

Efeito do laser de Nd:YAG do fluoreto de sódio na prevenção da erosão em dentina bovina através de perfilometria

Este estudo avaliou, através de perfilometria, a influência do laser de Nd:YAG, do verniz de flúor e da associação de ambos na perda de estrutura dentinária após 5 dias de desafio erosivo e após 7 dias de armazenamento em saliva artificial. Sessenta blocos de dentina bovina foram incluídos em resina acrílica, polidos e limpos em ultra-som. Cinco grupos (n=12) foram obtidos: C (controle); F (verniz NaF 5% por 6h); L (laser Nd:YAG: 1 W, 100 mJ, 10 Hz, 30 s, 124,37 J/cm2); LF (laser + verniz NaF); FL (verniz NaF + laser). Previamente aos tratamentos, metade da superfície foi protegida com fita para seladora e, após, realizou-se o desafio erosivo (ácido cítrico, 2 x 15 min/dia, 5 dias). A perfilometria foi realizada em três etapas: 1- após tratamento superfície; 2- após 5 dias de desafio erosivo; 3- após 5 dias de desafio erosivo + 7 dias de armazenamento. O objetivo da etapa 1 foi determinar a perda de estrutura pós-tratamento de superfície. Uma fatia de dentina adicional de cada grupo foi confeccionada para a realização de análise de Espectroscopia por Energia Dispersiva de Raio-x e de Microscopia Eletrônica de Varredura de cada etapa. Os dados de perfilometria das Etapas 2 e 3 foram analisados estatisticamente através de ANOVA de medidas repetidas dois fatores e Teste de Tukey (pC (4,33 d) >FL (3,46 de) =LF (3,13 de) >L (1,45 e). Na etapa 3, foram: F (8,59 a) = FL (8,19 a) > LF (7,45 ab) >C (6,78 abc) >L (4,35 cd). Concluiuse que: a) após o desafio erosivo, todos os tratamentos reduziram a perda dentinária, exceto o verniz de flúor; b) após o desafio erosivo seguido de 7 dias de armazenamento, todos os tratamentos perderam a efetividade, exceto o laser de Nd:YAG; c) nenhum dos tratamentos deteve a perda de cálcio e fósforo por erosão; d) todos os tratamentos...This study evaluated, by profilometry, the influence of Nd:YAG laser, fluoride varnish and the combination of both in the dentin structure loss after 5 days of erosive challenge and after 7 days storage in artificial saliva. Sixty bovine dentin blocks were embedded in acrylic resin, polished and cleaned in ultrasound. Five groups (n = 12) were obtained: C (control), F (5% NaF varnish for 6h), L (Nd:YAG laser: 1 W, 100 mJ, 10 Hz, 30 s, 124,37 J/cm2), LF (laser + NaF varnish ), FL (NaF varnish + laser). Prior to treatment, half of the surface was protected with sealing tape and, after, the erosive challenge was performed (citric acid, 2 x 15 min/day, 5 days). The profilometry was performed in three steps: 1- after surface treatment, 2- after 5 days of erosive challenge; 3- after 5 days of erosive challenge + 7 days of storage. The objective of step 1 was to determine the structure loss after surface treatment. An additional dentin slice of each group was prepared to perform Energy Dispersive Spectroscopy x-ray analysis of and Scanning Electron Microscopy for each step. Profilometry data of steps 2 and 3 were analyzed with two-way ANOVA for repeated measures and Tukey test (p C (4.33 d)> FL (3.46 de) = LF (3.13 de)> L (1.45 e). In step 3, the average loss were: F (8.59 a) = FL (8.19 a)> LF (7.45 ab)> C (6.78 abc)> L (4.35 cd). It was concluded that: a) after erosive challenge, all treatments reduced dentin loss, except fluoride varnish; b) after erosive challenge and 7 days of storage, all treatments lost their effectiveness, except Nd:YAG laser, c) none of the treatments prevented calcium and phosphorus loss by erosion; d) all treatments contributed to eroded dentin surface remineralization, e) morphological analysis was not conclusiveCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Avaliação de LEDs de alta intensidade quanto à eficiência de polimerização de resina composta e variação de temperatura na dentina bovina

Este estudo teve por objetivo avaliar a eficiência de polimerização de uma resina composta (RC) e a variação de temperatura na dentina bovina, empregando aparelhos de Diodo Emissor de Luz (LED) de alta intensidade em comparação a um aparelho de Quartzo-Halogênio-Tungstênio (QTH). Os aparelhos utilizados foram: Curing Light XL 3000 (3M, 600 mW/cm2), LED SmartLite PS (Dentsply, 950 mW/cm2) e LED Radii (SDI, 1400 mW/cm2) e a RC, a Esthet X (Dentsply). Para o teste de microdureza Vickers, foram confeccionados 84 corpos-de-prova (2 mm x 5 mm) em matriz de teflon bipartida, variando-se o tempo de exposição em 10, 20 e 40 s, sendo que o aparelho XL 3000 foi utilizado para o grupo controle apenas pelo tempo de 40 s. Após 24 h, realizou-se o teste de microdureza no topo e na base dos corpos-de-prova com carga de 50 g e duração de 15 s. Para a medida da variação de temperatura ocasionada pelos aparelhos, foram utilizadas 45 fatias de dentina bovina de 0,7 mm de espessura e termopar tipo T conectado a um sistema de aquisição de dados ADS 2000 IP (Lynx Tecnologia). As fatias foram divididas em três grupos, sendo a variação de temperatura medida em três etapas: 1) durante a fotopolimerização do adesivo (10 s); 2) durante a fotopolimerização da RC (40 s) e 3) após 24 h (40 s). Os valores de microdureza do topo e da base e os dados de temperatura foram submetidos ao teste ANOVA de medidas repetidas e aos testes de Tukey e Dunnet (p=5%). Os resultados revelaram diferença estatística significante de microdureza no topo e na base quando se utilizaram ambos os LEDs por 10 s em relação ao uso do XL 3000 por 40 s, não havendo diferenças estatísticas entre os grupos com os tempos de 20 s e 40 s. A utilização do LED Radii pelos tempos de 10 e 20 s não foi suficiente...The aim of this study was to evaluate the efficiency of polymerization of a resin composite and the temperature variation in bovine dentine, using two curing units of Light Emitting Diode (LED) of high intensity in comparison to a Quartz-Halogen-Tungsten device (QTH). The light curing units used were: Curing Light XL 3000 (3M, 600 mW/cm2), LED SmartLite PS (Dentsply, 950 mW/cm2) and LED Radii (SDI, 1400 mW/cm2) and the resin composite, Esthet X (Dentsply). For the test of Vickers microhardness, 84 specimens (2 mm X 5 mm) were prepared in bipartite matrix of teflon, varying the time of exposition in 10, 20 and 40 s. The curing unit XL 3000 was used for the control group for 40 s. After 24 h, the microhardness test was made on the top and base of the specimens with 50 g of load and 15 s of duration. For the temperature variation measurement caused by the different curing units, 45 slices of bovine dentine of 0.7 mm thickness and a thermocouple type T hardwired to a system of data acquisition ADS 2000 IP (Lynx Technology) were used. The slices were divided in three groups and the temperature variation was measured in three stages: 1) during the adhesive photopolymerization (10 s); 2) during resin composite photopolymerization (40 s) and 3) after 24 h (40 s). The values of microhardness of the top and the base and the data of temperature variation were submitted to ANOVA of repeated measures test and to the tests of Tukey and Dunnet (p=5%). The results showed statistical significant difference of microhardness for the top and base values when both LEDs were used for 10 s in relation to the use of XL 3000 for 40 s, but no statistical differences were found between the groups when the exposition time was 20 s and 40 s. The use of LED Radii for 10 s and 20 s was not enough to equal statistically ... (Complete abstract, click electronic access below)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES