Abstract This study evaluated the influence of activation modes, on Diametral Tensile Strength (DTS) of dual cured resin cements subjected to a Mechanical Fatigue test (MF). Four dual-cured resin cements (RelyX UNICEM [U], RelyX ARC [A], ENFORCE [E] and Nexus 2 [N]) were activated by three different curing modes as follows: Self-Curing (SC), Dual Cure activation with photoactivation executed directly (DC) and Dual Cure activation with Photoactivation Through Porcelain (DCTP). After 24 hours, half of the sample was subjected to 30.000 fatigue cycles at 1 Hz frequency and 12 N load. Then, all specimens were subjected to DTS test in Instron Universal Testing Machine and data were analyzed by three-way ANOVA and Tukey’s Test (5%). The results of DTS test means (MPa) and standard deviation, for each cement factor activated by SC, DC and DCTP was respectively: U (28.12 ± 5.29; 37.44 ± 6.49 and 40.10 ± 4.39), A (49.68 ± 8.42; 55.12 ± 5.16 and 63.43 ± 6.92), E (49.12 ± 3.89; 56.42 ± 8.88 and 56.96 ± 6.45) and N (61.89 ± 11.21; 59.26 ± 9.47 and 62.56 ± 10.93). Turkey’s test indicated that DC is related to the highest DTS values; Nexus 2 DTS remained the same independently of activation mode and that the Porcelain disk interposition enhanced DTS only for RelyX ARC the ANOVA statistical test indicated that MF didn’t alter the DTS values for all experimental groups. MF results clinical implication is that all cements tested exhibited, in an immediate loading, good cross linked bonds quality.

Resumo O objetivo deste estudo foi descrever uma técnica de dessensibilização dental imediata, usando o adesivo universal em paciente adolescente diagnosticado com amelogênese imperfeita. O paciente afetado pela amelogênese imperfeita apresentava dentes extremamente sensíveis, e foi submetido a aplicações de adesivo universal para dessensibilizar os dentes afetados por amelogênese imperfeita. A redução da sensibilidade dentária foi avaliada pela escala analógica visual durante todas as reavaliações. A técnica foi efetiva na redução da sensibilidade dental. Concluiu-se que o uso do sistema adesivo foi eficaz na imediata dessensibilidazação dentária e mantida após doze meses de avaliação.

Abstract The aim of this paper was to describe a clinical case of immediate dental desensitization using a self-etch adhesive system in an adolescent patient diagnosed with amelogenesis imperfecta (AI). AI was associated with severe tooth sensitivity, treated by the application of a universal adhesive system for desensitization of the teeth affected by AI. Reduction of tooth sensitivity was assessed using a visual analog scale during all reevaluations. The technique was effective for reducing tooth sensitivity. It was concluded that the adhesive system for tooth desensitization had an immediate effect and maintained its effectiveness during a 12-month follow-up period.

INTRODUÇÃO: foram avaliadas as forças de cisalhamento após colagem de braquetes ortodônticos em superfícies resinosas microparticuladas ou micro-híbridas, após diferentes tratamentos de superfície. MÉTODOS: foram utilizados 280 corpos de prova, divididos em grupos de 10 elementos cada, sendo 140 preenchidos com resina microparticulada Durafill e 140 com resina micro-híbrida Charisma. Os tratamentos de superfície envolveram: ácido fosfórico, ácido fluorídrico, jato de bicarbonato de sódio, jato de óxido de alumínio, pedra e broca. A silanagem foi utilizada em metade dos grupos. O cisalhamento foi realizado com a máquina universal de testes EMIC DL 10000 MF, com célula de 10kg e velocidade de 0,5mm/min. As comparações entre as forças de cisalhamento foram obtidas por meio da análise de variância, e o grau de interação entre os tipos de compósito e o preparo de superfície foram obtidos por meio de uma regressão multivariada. RESULTADOS: as médias e desvios-padrão foram: jato de bicarbonato = 11,27 ± 2,78; broca = 9,26 ± 3,01; pedra = 7,95 ± 3,67; jato de óxido de alumínio = 7,04 ± 3,21; ácido fosfórico = 5,82 ± 1,90; ácido fluorídrico = 4,54 ± 2,87; e sem preparo = 2,75 ± 1,49. Um acréscimo de 1,94MPa foi obtido com o uso do compósito Charisma. A silanagem reduziu em 0,68MPa as médias do compósito Charisma, e aumentou o Durafill com uso do jato de bicarbonato (0,83), broca (0,98) e pedra (0,46). CONCLUSÃO: os preparos com jato de bicarbonato, broca e pedra obtiveram médias de forças apropriadas para colagem. O compósito Charisma apresentou forças de maior intensidade que as da resina Durafill.

INTRODUCTION: The shear bond strength of orthodontic brackets bonded to micro-hybrid and micro-particulate resins under different surface treatment methods was assessed. METHODS: Two hundred and eighty test samples were divided into 28 groups (n = 10), where 140 specimens were filled with Durafill micro-particulate resin and 140 with Charisma composite. In 140 samples, a coupling agent (silane) was applied. The surface treatment methods were: Phosphoric and hydrofluoric acid etching, sodium bicarbonate and aluminum oxide blasting, stone and burs. A Universal Instron Machine was used to apply an occlusal shear force directly to the resin composite bracket surface at a speed of 0.5 mm/min. The means were compared using analysis of variance and multivariate regression to assess the interaction between composites and surface treatment methods. RESULTS: Means and standard deviations for the groups were: Sodium bicarbonate jet 11.27±2.78; burs 9.26±3.01; stone 7.95±3.67; aluminum oxide blasting 7.04±3.21; phosphoric acid 5.82±1.90; hydrofluoric acid 4.54±2.87, and without treatment 2.75±1.49. An increase of 1.94 MPa in shear bond strength was seen in Charisma groups. Silane agent application reduced the Charisma shear bond strength by 0.68 Mpa, but increased Durafill means for bicarbonate blasting (0.83), burs (0.98) and stone drilling (0.46). CONCLUSION: The sodium bicarbonate blasting, burs and stone drilling methods produced adequate shear bond strength and may be suitable for clinical use. The Charisma micro hybrid resin composite showed higher shear bond means than Durafill micro particle composite.

RelyX TM Unicem, dual-curing self-adhesive resin cement, was tested in order to evaluate the degree of conversion (DC) and Vickers microhardness (VMH). The specimens were prepared into 4 groups (GR). For GR1, the specimens were irradiated with 500 mW.cm-2 during 20 seconds while for GR3 the same intensity was used but the irradiation time was 40 seconds. The GR2 followed the same polymerization mode of the GR1 but a ceramic disk was applied as a light barrier. For the last group, only the chemical polymerization was carried out. The DC and VMH were measured immediately after the irradiation time and again after 24 hours. Dual-polymerization (light and chemical polymerization) showed higher DC and VMH than the chemical polymerization (dark cure). The presence of a ceramic disk did not affect the DC but reduced the VMH. Increasing the exposure to light, the DC remained almost constant whereas the VMH raised slightly indicating that the VMH is quite dependent on the incident energy. Additionally, the powder/liquid portions of the cement were also characterized. The TG showed that the solid fraction was constituted of 96% of inorganic matter and 4% of vinyl-silane, a coupling agent. Regarding the liquid part, it was found that 84% was related to the mixture of monomers. The SEM revealed that the size particle of the inorganic fillers were between 400 and 11.000 nm. Factors such as energy density, size and distribution of inorganic fillers and the low effectiveness of the chemical cure contributed to the low values of the DC and VMH.

The purpose of this study was to investigate the superficial rugosity of commercially pure titanium cast, under the action of different fluoride dental solutions and synthetic saliva. All specimens received the standard metallography procedure for titanium and were divided in groups: Group 1) synthetic saliva pH 7.0; Group 2) 1.23% APF gel pH 3.5;, Group 3) 2% NaF gel pH 6; Group 4) 0.05% NaF solution pH 4.0; and Group 5) 0.05% NaF solution pH 7.5. The specimens were exposed to these solutions for 16 minutes and immersed in synthetic saliva for 96 hours. The surfaces were analyzed in a roughness device and the results were statistically treated - Snededor 'F' and Bonferroni test. In addition, scanning electron microscopy was employed to observe the surface morphology after the test. The Group 2 was the only one which had a significant increase in the superficial roughness. Authors concluded that the fluoride solutions of dental use that have a high concentration of fluoride and low pH are harmful to the surface of cast titanium.

New types of copolymers using monomers which form inorganic polymers network (glass-like) and organic networks have been developed, known as ormocers. The aim of this work was to study how a particular dental filling material is degraded when subjected to a caries challenge by using low pH solutions. The supernadants were studied by HPLC to detect the presence of molecules from the resin, while the changes of the material surface were evaluated by contact angle. An organic modified ceromer (ormocer) called Definite® (Degussa ) was tested. Samples were built following manufacturer's instructions. After pH cycles, solutions were injected in a HPLC. The contact angle was obtained using a goniometer after and before the cycles. HPLC results showed material degradation, only detected in acid solutions. Bis-GMA and TEGDMA were detected in Definite® residues. Means and S.D. of contact angle were (p < 0,05): baseline: 85.16° ± 3.90° and after pH cycles: 69.77° ± 7.12°. The authors concluded that an ormocer filling material degraded on a caries simulated environment.

O objetivo desse estudo foi comparar o efeito de um adesivo autocondicionante e de um ácido não lavável quanto a profundidade de penetração na dentina de dentes humanos, através da observação em Microscopia Eletrônica de Varredura (MEV). Quinze terceiros molares tiveram a dentina exposta, cortando-se a face oclusal, planificados com lixa d'água 600, cortados transversalmente e distribuídos em 6 grupos de 5 cada: grupo 1 - Prime Bond NT (NT), controle negativo; grupo 2 - ácido fosfórico 37% + Prime Bond NT (PANT), controle positivo; grupo 3 - Non-Rinse Conditioner (NRC) + Prime Bond NT (NRCNT); grupo 4 - NRC + Prime Bond 2.1 (NRCPB); grupo 5 - NRC + Scotch Bond MP (NRCSB) e grupo 6 - Prompt L-Pop (PLP). Todos foram recobertos com Dyract AP. Os fragmentos dentários foram descalcificados com HCl a 10% e NaOH a 5% e as réplicas em resina examinadas em MEV. Três examinadores calibrados avaliaram as fotomicrografias e atribuíram escores de 0 = sem penetração a 3 = penetração máxima. Os testes de Kruskal-Wallis e Mann-Whitney (P<0,05) evidenciaram três grupos homogêneos {NT, NRCPB, NRCSB e PLP}; {NRCNT} e {PANT}. Os autores concluíram que o sistema adesivo autocondicionante e o ácido não lavável apresentaram menor penetração em dentina do que o sistema adesivo convencional.

The purpose of this study was to compare the effect of a self-etching primer and a non-rinse conditioner with the effect of a conventional adhesive system on the penetration depth in dentin of human teeth, using scanning electronic microscopy (SEM). Fifteen human third molar teeth were sectioned into 2 pieces. All pieces were flattened with grade 600 to 1200 silicon carbide paper and divided into 6 groups: group 1 - Prime & Bond NT (NT), negative control; group 2 - 37% phosphoric acid + Prime & Bond NT (PANT), positive control; group 3 - Non-rinse Conditioner (NRC) + Prime & Bond NT (NRCNT); group 4 - NRC + Prime & Bond 2.1 (NRCPB); group 5 - NRC + Scotchbond MP (NRCSB); group 6 - Prompt L-Pop (PLP). All teeth were covered with Dyract AP. The tooth fragments were decalcified, and its resin replicas were evaluated by SEM by three previously standardized examiners. The penetration was scored from 0 (no penetration) to 3 (maximum penetration). The Kruskal-Wallis and Mann-Whitney U tests (p<0.05) showed three statistically homogeneous groups: {NT, NRCPB, NRCSB and PLP}, {NRCNT} and {PANT}. The authors concluded that the self-etching primer and the non-rinse conditioner provide a lower penetration depth in human tooth dentin than the conventional adhesive system.