Can composition and preheating improve infiltrant characteristics and penetrability in demineralized enamel?

Abstract The composition of infiltrants can influence their physical properties, viscosity and depth of penetration (DP). Strategies are used to increase the DP, such as the addition of diluents or the use of heat. This study aimed to evaluate the effect of preheating and composition on physical properties and DP of infiltrants in demineralized enamel. The groups were assigned, and the following experimental formulations were made: 25%BisEMA +75%TEGDMA; 25%BisEMA +65%TEGDMA +10%ethanol; 25%BisEMA +65%TEGDMA +10%HEMA; 100%TEGDMA; 90%TEGDMA +10%ethanol; 90%TEGDMA +10%HEMA. The samples were photoactivated at two temperatures (25°C and 55°C). Degree of conversion (DC) was performed using an infrared spectrophotometer. Elastic modulus (E), flexural strength (FS) and contact angle (CA) tests were also performed. The DP of an infiltrant in demineralized enamel was determined by confocal laser scanning microscopy (CLSM) using an indirect labeling technique. The data were analyzed by two-way ANOVA and Tukey's test. DC increased after preheating in all the groups; however, 90%TEGDMA+10%ethanol showed the lowest DC for both temperatures, and the lowest E. Preheating did not influence E or FS. The CA increased at 55°C for most groups, but decreased for groups containing HEMA. Temperature did not seem to influence DP, and Icon showed the lowest DP values. The 100%TEGDMA composition showed more homogeneous penetration, whereas Icon showed heterogeneous and superficial penetration. The preheating technique does not improve all properties in all the material compositions. The composition of a material can influence and improve its properties.

Influence of different shades and LED irradiance on the degree of conversion of composite resins

The aim of this study was to evaluate the degree of conversion (DC) of two composite resins with different shades that were light cured by light-emitting diodes (LEDs) of different irradiances. Specimens (5 mm ' 2 mm) were prepared with a nanofilled (Filtek Supreme - A2E, A2D, and WE) or microhybrid resin (Opallis - A2E, A2D, and EBleach Low) and were randomly divided into 12 groups (n = 5 each) according to the composite resin and light-curing unit (Elipar FreeLight 2, 1250 mW/cm²; Ultralume 5, 850 mW/cm²). After 24 h, the DC was measured on two surfaces (top and bottom) with Fourier Transform infrared spectroscopy (FTIR). Data were statistically analyzed with two-way ANOVA and Tukey test (a = 0.05). Statistical differences among the surfaces were observed in all experimental conditions, with higher values on the top surface. The microhybrid resin presented the highest DCs for shades A2E and A2D on the top surface. The LED with higher irradiance promoted better DCs. Taken together, the data indicate that the shade of a composite resin and the irradiance of the light source affect the monomeric conversion of the restorative material.

Diferentes alternativas de clareamento para dentes escurecidos tratados endodonticamente / Different alternatives for bleaching endodontically treated teeth stained

O clareamento de dentes escurecidos e tratados endodonticamente constitui-se em uma possibilidade de tratamento estético que oferece maior preservação da estrutura dental e baixo custo, especialmente quando comparado aos procedimentos invasivos, como a confecção de facetas ou coroas. O peróxido de hidrogênio, o peróxido de carbamida e o perborato de sódio podem ser utilizados na superfície externa e interna dos dentes ou aplicados no interior da câmara pulpar, seguido pelo selamento coronário e troca do material clareador, em períodos de tempo pré-estabelecidos – técnica conhecida como Walking bleach. A aplicação de calor, visando a acelerar a reação química do clareamento dental (técnica termo-catalítica) tem sido questionada pelo fato de se constituir em um possível fator de risco para o desenvolvimento de reabsorção radicular externa, principalmente quando existe histórico de trauma dentário ou defeitos no cemento radicular. Portanto, a indicação precisa do material a ser utilizado deve ter como base o conhecimento da eficiência dos diversos agentes e a segurança do tratamento por eles oferecida. Assim, o objetivo deste estudo é revisar a literatura, considerando as diferentes alternativas de clareamento para dentes tratados endodonticamente e escurecidos, abordando os agentes clareadores mais utilizados, as diferentes técnicas, vantagens e desvantagens, e possíveis efeitos colaterais advindos dessas técnicas.

Agenesia Congênita de Terceiros Molaresem Radiografias Panorâmicas / Agenesy Congenital of Third Molar Absence in Panoramic Radiographs

Avaliar a prevalência de ausência congênita dosterceiros molares em radiografias panorâmicas. Material eMétodos: A amostra foi composta por 225 radiografias decrianças entre 10 e 15 anos de idade, em tratamentoortodôntico, em clínicas odontológicas particulares da cidadede Salvador-BA. A história clínica dos pacientes permitiuexcluir da amostra a ausência de terceiros molares porextração. Resultados: Os resultados mostraram que afreqüência de ausência congênita de terceiro molar foi de27,5%, sendo que a anomalia ocorreu de forma maisprevalente no gênero feminino e o primeiro quadrante foiaquele no qual ocorreu a maior taxa de ausência (59,67%).Conclusão: A arcada superior e o lado direito foram os maisafetados, e a ausência dos quatro terceiros molares foiencontrada em 17,7% da amostra...

Evaluate the prevalence of congenital absenceof the third molars in panoramic radiographs. Materials andMethods: The sample was composed of 255 radiographs ofchildren under the age of 10 and 15 years old, under anorthodontic treatment, at private orthodontic clinics in the cityof Salvador – BA. The patients’ clinical history allowed theexclusion of the congenital absence of the third molar byextraction out of the samples. Results: The results showthat the frequency of the congenital absence of the thirdmolar was 27,5% , and the anomaly was more prevalent infeminine gendered patients. They also show that the firstquarter was the one that the major tax of absence occurred(59,6%). Conclusion: The upper arch and the right side werethat ones mostly affected, and the absence of four thirdmolars was found in 17,7% of the sample...