Evaluation of shear bond strength and shear stress on zirconia reinforced lithium silicate and high translucency zirconia

This study evaluated the shear stress distribution on the adhesive interface and the bond strength between resin cement and two ceramics. For finite element analysis (FEA), a tridimensional model was made using computer-aided design software. This model consisted of a ceramic slice (10x10x2mm) partially embedded on acrylic resin with a resin cement cylinder (Ø=3.4 mm and h=3mm) cemented on the external surface. Results of maximum principal stress and maximum principal shear were obtained to evaluate the stress generated on the ceramic and the cylinder surfaces. In order to reproduce the in vitro test, similar samples to the computational model were manufactured according to ceramic material (Zirconia reinforced lithium silicate - ZLS and high translucency Zirconia - YZHT), (N=48, n=12). Half of the specimens were submitted to shear bond test after 24h using a universal testing machine (0.5 mm/min, 50kgf) until fracture. The other half was stored (a) (180 days, water, 37ºC) prior to the test. Bond strength was calculated in MPa and submitted to analysis of variance. The results showed that ceramic material influenced bond strength mean values (p=0.002), while aging did not: YZHT (19.80±6.44)a, YZHTa (17.95±7.21)a, ZLS (11.88±5.40)b, ZLSa (11.76±3.32)b. FEA results showed tensile and shear stress on ceramic and cylinder surfaces with more intensity on their periphery. Although the stress distribution was similar for both conditions, YZHT showed higher bond strength values; however, both materials seemed to promote durable bond strength.

Biomechanical behavior of indirect composite materials: a 3D-FEA study / Comportamento biomecânico de resinas compostas indiretas: um estudo 3D-FEA

Objective: Este estudo teve como objetivo avaliar a influência do módulo de elasticidade de resinas compostas indiretas (RCI) na distribuição de tensão de um primeiro pré-molar superior restaurado. Materiais e métodos: Um modelo de elemento finito tridimensional (3D) de um dente com restauração mesio-ocluso-distal (MOD) foi utilizado. Foram simulados três RCI, alterando o módulo de elasticidade: 10, 15 e 20 GPa. Todos os materiais foram considerados isotrópicos, homogêneos, lineares e elásticos. Uma carga axial (200 N) foi aplicada na superfície oclusal através de uma esfera, e os nós da superfície externa das raízes foram fixados. Foi analisada a Tensão Máxima Principal no dente e na restauração. Resultados: De acordo com a análise, quanto menor for o módulo elástico da RCI, maiores são os valores de tensão de tração gerados no dente. Para a restauração, observou-se o oposto: quanto menor o módulo, menor a tensão de tração. Conclusão: Com as limitações deste estudo, é possível concluir que quanto maior o módulo de elasticidade do material restaurador, mais difícil será a deflexão das cúspides, mas, a fratura da resina será mais fácil.(AU)

Objetivo: This study aimed to evaluate the influence of the elastic modulus of indirect composite resins (ICR) in the stress distribution of a restored maxillary first premolar. Material and methods: A three-dimensional (3D) finite element model of the tooth and the mesialocclusal-distal (MOD) restoration was created. Three ICR were simulated, by changing the elastic modulus: 10, 15 and 20 GPa. All materials were considered as isotropic, homogeneous and linearly elastic. An occlusal load (200 N) was applied on occlusal surface trough a sphere, and the nodes of the external surface of the root were fixed. The maximum principal stresses on the tooth and restoration were analyzed. Results: According to FE analysis, the lower the ICR elastic modulus, the higher the tensile stress values generated on the remaining tooth. For the restoration, the opposite was observed: the lower the modulus, the lower the tensile stress. Conclusion: With the limitations of this study it is possible to conclude that the greater the elastic modulus of the restorative material the harder it will be to deflect the cusps, but the easier the fracture of the resin(AU)

Comparison of the marginal microleakage of three cavity restoration methods / 实用口腔医学杂志

Objective:To compare the marginal microleakage of class V cavity restored with composite resin by 3 different methods. Methods:Class Ⅴ cavity was prepared in 36 human third molars,the teeth were randomly divided into 3 groups(n =1 2)and were repaired with common Z350 resin,pre-heated Z350 resin and Z350 resin inlay,respectively.After thermal cycling for 500 times the teeth were immersed in fuchsin solution for 24 h.Then the samples were sectioned longitudinally and examined for leakage under stereomicroscope.Results:The microleakage of cavity restoration by pre-heated Z350 resin and Z350 resin inlay was significantly low-er than that of the direct restoration with Z350 resin(P≤0.05).No significant difference was found between the groups of pre-heated Z350 resin and Z350 resin inlay.Conclusion:Marginal microleakage of Z350 resin restoration can be decreased by preheating of the resin.

Cuspal deflection of directly or indirectly restored teeth / Deflexão cuspídea de dentes restaurados direta ou indiretamente

Objective: The aim of this study was to evaluate the cuspal deflection of teeth restored directly and indirectly. Material and Methods: Forty sound maxillary premolar teeth were restored with composite and different base materials. Wide mesial-occlusal-distal cavity preparations were performed, with isthmus width of one third of the distance between the cuspal tips, 3 mm occlusal and a 5 mm interproximal preparation height. The teeth were divided into 4 groups (n = 10), according to the restoration type: G1) GIC-DCR (1 mm glass ionomer cement base and direct restoration using nanoparticulate composite); G2) FL-DCR (1 mm base of flowable composite resin and direct restoration using nanoparticulate composite); G3) GIC-ICR (1 mm glass ionomer cement base and indirect restoration using nanoparticulate composite GIC base); G4) FL-ICR (1 mm base of flowable composite resin and indirect restoration using nanoparticulate composite). The specimens were submitted to compressive load of 50 N on the buccal and lingual cusps, in a universal testing machine. The lingual cusp microstrain (με) measurements were executed by strain gauges. Results: The Kruskal-Wallis (5%) test was used and showed there were no significant differences among the microstrain values for the four study groups (G1 = 1250; G2 = 1075; G3 = 1279; G4 = 937). Conclusion: It could be concluded that the restorative techniques and the bases employed did not show any influences in cuspal deflection

Objetivo: O objetivo deste trabalho foi avaliar, por meio de medidores de tensão, a deflexão cuspídea sofrida por dentes restaurados, direta e indiretamente, com resinas compostas e diferentes materiais de base. Material e Métodos: Para o preparo dos corpos-de-prova (CP) foram utilizados 28 dentes pré-molares humanos íntegros, extraídos por razões ortodônticas que tiveram suas raízes embutidas em poliuretano de densidade semelhante a do osso e suas raízes recobertas por um espaçador visando simular o espaço referente ao ligamento periodontal. Na etapa seguinte os dentes receberam preparos cavitários do tipo mésio-ocluso-distais amplos e então restaurados direta e indiretamente com resina composta e dois diferentes materiais de base/forramento, resina flow e cimento de ionômero de vidro. Para a realização das medidas de deflexão das cúspides foram utilizados extensômetros lineares elétricos colados à face lingual de cada dente e submetidos a uma carga de 50 N aplicada por uma ponta romba de diâmetro de 3,0 mm, que promoveu compressão simultânea nas vertentes triturantes das cúspides vestibular e lingual, numa máquina universal de ensaios. Resultados: Foi realizado o teste de Kruskall-Wallis (5%) de significância e não foram encontradas diferenças estatísticamente significantes entre os grupos (G1 – 1250; G2 = 1075; G3 = 1279; G4 = 937). Conclusão: Pode-se concluir que o tipo de restauração bem como o tipo de base empregados nesse estudo não alteram a deflexão cuspídea dos dentes com restaurações amplas.

Uso de restaurações indiretas na correção da infra-oclusão: relato de caso / Use of indirect restorative technique for the correction of retained primary molar: case report

A infraoclusão de molares decíduos é uma situação clínica que pode causar prejuízos ao desenvolvimento da oclusão do paciente, mas com o desenvolvimento das técnicas e materiais odontológicos nos últimos anos, esse quadro clínico pode ser solucionado através de uma terapia mais conservadora. Este trabalho tem como objetivo apresentar a reabilitação de um dente em infraoclusão através da utilização de uma restauração indireta em resina composta. Esta técnica permite restabelecer as dimensões anatômicas, o equilíbrio oclusal e a estética da criança. Ao final pôde-se concluir que as restaurações indiretas em resina são uma boa opção de tratamento conservador para os casos de infraoclusão na dentição decídua.

Infraoccluded primary molars is a common clinical situation that can cause several damages for the development of occlusion, but with today?s development of the techniques and dental materials these clinical situation has several ways to be resolved, returning the oclusal balance for the patient. This article had as aim present a clinical report of a rehabilitation of an infraoccluded primary molar with the use of an indirect restoration in composite resin, designed to restore the anatomical size, the occlusion and esthetics of the child. At the end we can conclude that this technique presents several advantages, especially in Pediatric Dentistry.

Reabilitação estética indireta utilizando o sistema In-Ceram Zircônia - relato de caso clínico / Rehabilitation aesthetic indirect using In-Ceram Zirconium - report of clinical case

As porcelanas odontológicas foram desenvolvidas no intuito de atender a demanda por materiais mais estéticos e resistentes. Buscou-se através do caso clínico apresentar o tratamento reabilitador de um tipo de sistema cerâmico, o In-Ceram-Zircônia, enfatizando suas indicações, vantagens e limitações. Constatou-se que as cerâmicas reforçadas com o óxido de Zircônio possuem propriedades estéticas e adequada adaptação marginal. Sendo mais resistentes que quaisquer outras próteses livres de metal disponíveis no mercado devido a sua grande resistência à flexão, podendo substituir as restaurações metalo-cerâmicas, respeitando as poucas limitações do sistema.

The dental porcelains were developed in the intention of assisting the demand for more aesthetic materials (metal free) and resistant. It was searched through a clinical case present the treatment of a type of forward ceramic system, In-Ceram, emphasizing its indications, advantages and limitations. It marginal adaptation. Being more resistant than any other metal free prostheses available in the market due to its great resistance to the flexing, being able to substitute the metal ceramic restoration, respecting the few limitations of the system.

Effect of cavity preparation design on the fracture resistance of directly and indirectly restored premolar

Aim: The aim of this study was to evaluate the fracture resistance of human premolars with extensive cavity preparations of the inlay and onlay types, for performing direct and indirect composite resin restorations. Methods: Eight-four premolars were divided into 7 groups (n=12): G1=intact teeth; G2=inlay/Filtek Z-250 direct; G3=inlay/ Filtek Z-250 light polymerized indirectly; G4=inlay/ Solidex; G5=onlay/ Filtek Z-250 direct; G6=onlay/ Filtek Z-250 light polymerized indirectly; G7=onlay/ Solidex. Indirect Filtek Z- 250 restorations were light activated using the EDG-lux oven. All samples were submitted to axial compression load in a Universal Testing Machine until fracture. The data were submitted to the one-way ANOVA and Tukey’s test (a=0.05). Results: The results (N) were: G6-1938a, G5-1570ab, G7-1285b, G1-1215b, G4-1174b, G3-1146b and G2-1112b. The onlay cavities restored indirectly with Filtek Z-250 presented significantly higher fracture resistance (G6) than the other groups, except for onlay restorations made directly with Filtek Z-250 (G5), which, in turn, did not differ significantly from the other groups. However, the onlay restorations made with Filtek Z-250 led to more catastrophic failure modes. Conclusions: 1. Adhesive inlay restorations, irrespective of the type of composite resin and light-activation technique used, restored the fracture resistance of intact teeth.

1 year follow-up study of direct and indirect composite restorations / 대한치과보존학회지

BACKGROUND: The purpose of the present study was to evaluate the direct and indirect composite restorations which had been placed for 1 year. METHODS: The composite restorations which had been placed between 1999. Mar and 1999, Dec was evaluated after 1 year. For direct restorations, Spectrum (Dentsply, USA) and Z100 (3M, USA) were used in the anterior teeth and Surefil (Dentsply, USA) were used. For class V restorations of anterior and posterior teeth, Spectrum was used. For indirect restorations, Targis/Vectris system (Vivadent/Ivoclar, Liechtenstein) was used. 2 examiners evaluated marginal quality, proximal contact, discoloration, presence of 2nd caries, loss of filling and hypersensitivity of restorations. The restorations was clinically evaluated by modified methods based on USPHS. RESULTS: 60 teeth were evaluated. 59 were clinically acceptable and 1 restoration which was placed in class v cavity in the posterior tooth was fallen out. In most cases, the restorations were clinically acceptable. For restorations which had been directly placed in the class II cavities, loose proximal contact was indicated as the main complaints. CONCLUSIONS: Most of Anterior and posterior restorations which bad been directly or indirectly placed for 1 year were clinically acceptable. For posterior teeth, loose proximal contact was indicated as the main problem in the directly placed Class II restorations. Long term clinical study is needed.