Correlation between margin fit and microleakage in complete crowns cemented with three luting agents

Microleakage can be related to margin misfit. Also, traditional microleakage techniques are time-consuming. This study evaluated the existence of correlation between in vitro margin fit and a new microleakage technique for complete crowns cemented with 3 different luting agents. Thirty human premolars were prepared for full-coverage crowns with a convergence angle of 6 degrees, chamfer margin of 1.2 mm circumferentially, and occlusal reduction of 1.5 mm. Ni-Cr cast crowns were cemented with either zinc phosphate (ZP) (S.S. White), resin-modified glass-ionomer (RMGI) (Rely X Luting Cement) or a resin-based luting agent (RC) (Enforce). Margin fit (seating discrepancy and margin gap) was evaluated according to criteria in the literature under microscope with 0.001 mm accuracy. After thermal cycling, crowns were longitudinally sectioned and microleakage scores at tooth-cement interface were obtained and recorded at ×100 magnification. Margin fit parameters were compared with the one-way ANOVA test and microleakage scores with Kruskal-Wallis and Dunn's tests (alpha=0.05). Correlation between margin fit and microleakage was analyzed with the Spearman's test (alpha=0.05). Seating discrepancy and marginal gap values ranged from 81.82 µm to 137.22 µm (p=0.117), and from 75.42 µm to 78.49 µm (p=0.940), respectively. Marginal microleakage scores were ZP=3.02, RMGI=0.35 and RC=0.12 (p;0.05). Conclusion: Margin fit parameters and microleakage showed no strong correlations; cast crowns cemented with RMGI and RC had lower microleakage scores than ZP cement

Evaluation of depth of cure and Knoop hardness in a dental composite photo-activated using different methods

The aim of this study was to evaluate the depth of cure and Knoop hardness in the P60 composite resin photo-activated using different methods. A bipartite brass matrix (3 mm in diameter X 11 mm in height) was filled with the composite and photo-activation was performed using continuous light, exponential light, intermittent light, plasma arc curing (PAC) or light-emitting diodes (LED). After opening the matrix, the uncured material was removed with a steel spatula and the polymerized composite was measured using a pachymeter. The specimens were then included in self-curing acrylic resin and worn longitudinally and the hardness was measured on the surface and at depths of 1, 2, 3, 4 and 5 mm. The data were analyzed by ANOVA and Tukey's test (5%). The results showed that the depth of cure was higher with the intermittent light, followed by continuous light, exponential light, PAC and LED methods. Up to a depth of 2 mm, all methods revealed similar hardness values, but there were differences between them at other depths, at which LED demonstrated the lowest values followed by PAC.O objetivo deste trabalho foi avaliar a profundidade de polimerização e a dureza Knoop do compósito restaurador P60 fotoativado por diferentes métodos. Uma matriz metálica bipartida (3 mm de diâmetro X 11 mm de altura) foi preenchida com o compósito e fotoativada através da luz contínua, luz exponencial, luz intermitente, plasma de xenônio (PAC) ou luz emitida por diodo (LED). Após a abertura da matriz, o material não polimerizado foi removido com o auxílio de uma espátula metálica e o compósito polimerizado medido com um paquímetro digital. Então os espécimes foram incluídos em resina acrílica autopolimerizável e desgastados longitudinalmente e a dureza foi medida na superfície e nas profundidades de 1, 2, 3, 4 e 5 mm. Os dados foram analisados por ANOVA e teste de Tukey (5%). Os resultados mostraram que a profundidade de polimerização foi maior com a luz intermitente, seguida pela luz contínua, luz exponencial, PAC e LED. Até a profundidate de 2 mm, todos os métodos de fotoativação revelaram valores de dureza similares, porém diferiram a outras profundidades, onde o LED demonstrou os menores valores, seguido pelo PAC.19920

Avaliação em MEV do padrão de condicionamento do esmalte dental promovido por monômeros ácidos e o ácido fosfórico

ABSTRACT OBJECTIVE: Although self-etching bonding systems (SES) are indicated to prepare dental enamel for bonding, concerns have been expressed regarding their effectiveness. The aim of this study was to analyze the etching pattern (EP) of nine SES in comparison with 35% and 34% phosphoric acid etchants (FA) on intact (IN) and ground (GR) enamel surface. MATERIALS AND METHODS: Twenty-two human third molars were sectioned in mesial-distal and buccal-lingual directions, and four dental fragments were obtained from each tooth. Half of the fragments were ground using 600-grit SiC paper and the other half remained intact. The fragments were randomly assigned into 22 groups, according to the texture of enamel surface (IN and GR) and the technique to etch the enamel (34% FA, 35% FA, AdheSE primer; Brush & Bond; Clearfil Protect Bond primer; iBond; One-up Bond F; OptiBond Solo Plus primer; Tyrian SPE primer; Unifil Bond primer and Xeno III). Conditioners were applied to IN and GR enamel surfaces, according to the manufacturer's instructions. Specimens etched with phosphoric acids were washed with water, while the surfaces treated with SES were submitted to alternate rinsing with alcohol and acetone. The specimens were dried, sputter-coated and examined under a scanning electron microscope. RESULTS: For both IN and GR enamel surfaces, the EP of 34 and 35% FA was deeper and more homogeneous in comparison to EP of SES, except for Tyrian SPE. The acidic monomer action of self-etching systems was more effective on GR enamel. CONCLUSION: Most of the SES are less aggressive than phosphoric acid etchants and their etching effects were reduced on intact enamel surfaces.OBJETIVO: Apesar dos sistemas adesivos autocondicionantes (SAA) serem indicados para aplicação no esmalte dental, preocupação tem sido relatada com relação a sua efetividade. O objetivo deste estudo foi avaliar o padrão de condicionamento ácido (PCA) promovido por nove SAA e comparar ao PCA produzido pelo ácido fosfórico (35% e 34% - AF) no esmalte intacto (EI) ou abrasionado (EA). MATERIAIS E MÉTODOS: Vinte e dois terceiros molares humanos foram seccionados nos sentidos mésio-distal e vestíbulo-lingual, e quatro fragmentos dentais foram obtidos a partir de cada dente. Metade dos fragmentos tiveram o esmalte abrasionado com lixas de SiC (600) e a outra metade permaneceu intacta. Os fragmentos foram divididos em 22 grupos, de acordo com a textura da superfície do esmalte (EI e EA) e a técnica de condicionar o esmalte (AF 34 %, AF 35%, AdheSE primer; Brush & Bond; Clearfil Protect Bond primer; iBond; One-up Bond F; OptiBond Solo Plus primer; Tyrian SPE primer; Unifil Bond primer e Xeno III). Os agentes condicionadores foram aplicados nos EI e EA, de acordo com as instruções dos fabricantes. Espécimes tratados com AF foram lavados com água, enquanto os dentes tratados com SAA foram tratados com banhos alternados de álcool e acetona. Os espécimes foram secos, metalizados e observados em microscopia eletrônica de varredura. RESULTADOS: Em ambas as superfícies (EI e EA), o PCA dos AF (34 e 35%) foi mais profundo e homogêneo, quando comparados ao PCA produzido pelos SAA, exceto para o adesivo Tyrian SPE. A ação dos monômeros ácidos dos SAA foi mais efetiva no EA. CONCLUSÃO: A maioria dos SAA é menos agressiva que o ácido fosfórico e seus efeitos condicionadores são reduzidos em superfícies de EI

Efeito do uso de forradores resinosos sobre a microinfiltração de restaurações classe V em compósito odontológico

OBJETIVO: O objetivo desse estudo foi avaliar os efeitos da aplicação de um adesivo em diferentes espessuras ou em associação com um adesivo com carga ou com compósito de baixa viscosidade na microinfiltração marginal de restaurações com compósito odontológico. MÉTODOS: Quarenta incisivos bovinos foram selecionados e cavidades circulares (4mm de diâmetro X 2mm de profundidade) foram preparadas na região da junção cemento-esmalte. Os dentes foram então divididos em quatro grupos de acordo com o forramento utilizado: 1: (controle) aplicação do sistema de união Scotchbond Multi Uso (SBMU) - 1 camada de adesivo; 2: aplicação de 3 camadas do adesivo SBMU; 3: aplicação do SBMU, seguido pela aplicação de uma camada do adesivo Optibond FL; 4: aplicação do SBMU seguido pela aplicação de forramento com o compósito de baixa viscosidade Flow-it. Todas as cavidades foram restauradas com o compósito Z100. O teste de microinfiltração foi conduzido de acordo com a ISO (TR11405). Os dados foram analisados pelo teste de Kruskall-Wallis (p>;0,05). RESULTADOS: O grupo 4 apresentou redução significativa dos níveis de infiltração quando comparado ao grupo 1. Os grupos 2 e 3 apresentaram valores intermediários e não foram detectadas diferenças significativas quando estes grupos foram comparados aos grupos 1 e 4. CONCLUSÃO: O uso de forramento com compósito de baixa viscosidade pode reduzir os níveis de infiltração marginal, possibilitando melhora na qualidade das restaurações em compósito odontológico.PURPOSE: The aim of this study was to evaluate the effect of an adhesive applied in layers of different thickness or in association with a filled adhesive or with a low viscosity composite liner on the microleakage of composite restorations. METHODS: Forty bovine incisors were prepared with round cavities (4mm diameter X 2mm depth) on the cementoenamel junction. The teeth were assigned to four groups according to the liner used: 1 (control) - application of 1 layer of the Scotchbond Multi Purpose adhesive system (SBMP); 2 - application of 3 layers of SBMP; 3 - application of 1 layer of SBMP followed by application of one layer of Optibond FL adhesive; 4 - application of one layer of SBMP followed by application of flowable composite Flow-it. All cavities were restored using composite resin Z100. The microleakage test was conducted according to ISO (TR11405). Data were analyzed by Kruskall-Wallis test (a=0.05). RESULTS: Group 4 showed less leakage than Group 1. Groups 2 and 3 showed intermediate values and there were no statistical differences when they were compared to the values of Groups 1 and 4 CONCLUSION: The use of resin liners with flowable composites can reduce the microleakage of composite restorations

Comparison of in vivo and in vitro models to evaluate pulp temperature rise during exposure to a Polywave® LED light curing unit

Objectives: To measure and compare in vivo and in vitro pulp temperature (PT) increase (ΔTEMP) over baseline, physiologic temperature using the same intact upper premolars exposed to the same Polywave® LED curing light. Methodology: After local Ethics Committee approval (#255,945), local anesthesia, rubber dam isolation, small occlusal preparations/minute pulp exposure (n=15) were performed in teeth requiring extraction for orthodontic reasons. A sterile probe of a temperature measurement system (Temperature Data Acquisition, Physitemp) was placed within the pulp chamber and the buccal surface was sequentially exposed to a LED LCU (Bluephase 20i, Ivoclar Vivadent) using the following exposure modes: 10-s low or high, 5-s Turbo, and 60-s high. Afterwards, the teeth were extracted and K-type thermocouples were placed within the pulp chamber through the original access. The teeth were attached to an assembly simulating the in vivo environment, being similarly exposed while real-time temperature (°C) was recorded. ΔTEMP values and time for temperature to reach maximum (ΔTIME) were subjected to two-way ANOVA and Bonferroni's post-hoc tests (pre-set alpha 0.05). Results: Higher ΔTEMP was observed in vitro than in vivo. No significant difference in ΔTIME was observed between test conditions. A significant, positive relationship was observed between radiant exposure and ΔTEMP for both conditions (in vivo: r2=0.917; p<0.001; in vitro: r2=0.919; p<0.001). Conclusion: Although the in vitro model overestimated in vivo PT increase, in vitro PT rise was close to in vivo values for clinically relevant exposure modes

Effect Of Resin Liners On The Microleakage Of Class V Dental Composite Restorations.

The aim of this study was to evaluate the effect of an adhesive applied in layers of different thickness or in association with a filled adhesive or with a low viscosity composite liner on the microleakage of composite restorations. Forty bovine incisors were prepared with round cavities (4mm diameter X 2mm depth) on the cementoenamel junction. The teeth were assigned to four groups according to the liner used: 1 (control) - application of 1 layer of the Scotchbond Multi Purpose adhesive system (SBMP); 2 - application of 3 layers of SBMP; 3 - application of 1 layer of SBMP followed by application of one layer of Optibond FL adhesive; 4 - application of one layer of SBMP followed by application of flowable composite Flow-it. All cavities were restored using composite resin Z100. The microleakage test was conducted according to ISO (TR11405). Data were analyzed by Kruskall-Wallis test (a=0.05). Group 4 showed less leakage than Group 1. Groups 2 and 3 showed intermediate values and there were no statistical differences when they were compared to the values of Groups 1 and 4 The use of resin liners with flowable composites can reduce the microleakage of composite restorations.1256-6

Decreased dentin tubules density and reduced thickness of peritubular dentin in hyperbilirubinemia-related green teeth

It is stated anecdotally that patients with liver diseases in childhood who develop green teeth have increased risk for rampant caries, which may be secondary to changes in dental structure. The aim of this study was to test the hypothesis that hyperbilirubinemia affects the dentin morphology of green teeth. Sixteen primary teeth were prepared and divided into two groups (green teeth, n = 8 and control, n = 8), which were transversely fractured across the cervical third of the dental crowns; dentin was prepared and sputter-coated with gold, and examined under a scanning electron microscope. The mean density and mean diameter of dentin tubules, as well as the thickness of peritubular dentin, were compared. Hyperbilirubinemia was associated with a decrease in the density of the dentin tubules (p< .01) and the thickness of peritubular dentin of green teeth (p< .01). There was a correlation between childhood hyperbilirubinemia and changes in the dentin morphology, including a decrease in the density of the dentin tubules and a reduction in the thickness of peritubular dentin in green teeth

Postradiation Matrix Metalloproteinase-20 Expression and Its Impact on Dental Micromorphology and Radiation-Related Caries

Recent evidence suggests that head-and-neck radiotherapy (HNRT) increases active forms of matrix metalloproteinase-20 (MMP-20) in human tooth crowns, degrading the dentin-enamel junction (DEJ) and leading to enamel delamination, which is a pivotal step in the formation of radiation-related caries (RRC). Additional participation of enzymatic degradation of organic matrix components in caries progression was attributed to MMP-20 in dentin. Therefore, the current study tested the hypothesis that MMP-20 is overexpressed in the DEJ, dentin-pulp complex components, and carious dentin of post-HNRT patients, leading to detectable micromorphological changes to the enamel and dentin. Thirty-six teeth were studied, including 19 post-HNRT specimens and 17 nonirradiated controls. Optical light microscopy was used to investigate the micromorphological components of the DEJ, dentin-pulp complex components, and carious dentin. The samples were divided into 2 subgroups: nondemineralized ground sections (n = 20) and demineralized histological sections (n = 16). In addition, immunohistochemical analysis using the immunoperoxidase technique was conducted to semiquantitatively assess MMP-20 expression in the DEJ, dentin-pulp complex components, and carious dentin. No apparent damage to the DEJ microstructure or other dentin-pulp complex components was observed and no statistically significant differences were detected in MMP-20 expression (p > 0.05) between the irradiated and control groups. This study rejected the hypothesis that MMP-20 is overexpressed in the DEJ, dentin-pulp complex components, and carious dentin of post-HNRT patients, leading to detectable micromorphological changes. Hence, direct effects of radiation may not be regarded as an independent factor to explain aggressive clinical patterns of RRC. (C) 2017 S. Karger AG, BaselPeer reviewe

Dentin-pulp complex reactions in conventional and radiation-related caries : a comparative study

Radiation-related caries (RRC) is one of the most significant oral toxicities of head and neck radiotherapy (HNRT); however, the potential of radiation to directly cause harmful dentin and pulpal effects and impair response to caries progression is controversial. Therefore, the aim of this study was to characterize the reactions of the dentin-pulp complex in teeth affected by RRC. Patients and methods: Twenty-two carious teeth extracted from 22 head and neck cancer (HNC) patients were divided into control (conventional caries; n=11) and irradiated (RRC; n=11) groups and paired matched by dental homology, clinical patterns of caries progression following the Post-Radiation Dental Index (PRDI) and microscopic depth of carious invasion. Histopathological characteristics based on morphological hierarchy, cell populations of dental pulp, blood vessels, neural elements, extracellular matrix components, inflammation, patterns of carious invasion and reactionary dentin presence were evaluated by optical light microscopy and histomorphometry. Mean PRDI scores were 3.2 for the control group and 3.8 for the irradiated group. Dentin demineralization patterns were also similar between the groups and the mean depths of demineralization were 1,158.58µm and 1,056.89µm for the control and irradiated groups, respectively. Pulp histopathological changes and dentin reaction patterns were similar between groups and varied according to the PRDI scores and carious lesions depth. Dentin and pulp reactions are highly preserved in RRC teeth

The impact of head and neck radiotherapy on the dentine-enamel junction : a systematic review

Radiotherapy is widely used in contemporary head and neck cancer treatment protocols. The ability of head and neck radiotherapy (HNRT) to cause direct radiogenic destruction to the teeth is one of the most controversial topics in the field of oral oncology. Therefore, this systematic review aimed to investigate ionising radiation as an independent factor for physical and chemical changes on the dentine-enamel junction (DEJ), a pivotal dental topography for the onset and progression of radiation-related caries (RRC) and enamel delamination. Systematic searches were conducted on three databases: Scopus, MEDLINE (Via PubMed) and Embase (Elsevier). Laboratory studies evaluating the effects of simulated or in vivo HNRT on the DEJ were included. The GRADE tool adapted for in vitro studies was used to assess the methodological quality. Of the 154 initially selected studies, eight met the inclusion criteria, from which five studies were graded as high quality of evidence, two studies were graded as moderate quality and one as low quality. Two studies did not demonstrate DEJ alterations following HNRT while the other six articles described several organic and inorganic changes in the DEJ of irradiated teeth samples. These radiogenic events were mostly detected through micro and nanoindentation, Raman micro-spectroscopy, confocal microscopy, Western blotting and optical coherence tomography. HNRT may have a negative impact on the physical and chemical aspects of the DEJ, predisposing cancer patients to RRC and enamel delamination