Estudo in vitro da influência da dureza e módulo de elasticidade de sistemas adesivos na resistência de união à dentina humana

Abstract

Bengtson CRG. In vitro study of influence of hardness and elasticity module of adhesive sistems in bond strenght to human dentin [thesis]. São Paulo: Universidade de São Paulo, Faculdade de Odontologia; 2010.The aim of this study is to evaluate hardness and elasticity module of adhesive region of adhesive systems of different formulations immediately and 6 moths after the adhesive procedures. Those values will be compared to microtensile bond strength to human dentin. The hardness and elasticity module of composite resin next to adhesion region, adhesive layer, hybrid layer and dentin were evaluated.Forty sound human molars were used and prepared in order to obtain flat dentin surfaces in which the adhesive systems were applied following manufactures instructions (n=10). The groups were divided according the four adhesive systems:Adper Scotchbond Multipurpose, Adper Single Bond 2, Adper SE Plus and Clearfil SE Bond. Resin blocks of 5mm were constructed in those surfaces. After 24h of storage in distilled water at 37°C restored teeth were sectioned in order to obtain specimen with a bonded area of around 1mm 2 . Two specimen of each tooth were submitted to nanohardness and elasticity module test of adhesive interface. Half of the specimen were immediately submitted to the test with a crosshead speed of 0,5mm/min until fracture, the other specimen were stored for additional 6 month in 37ºC water prior to the test. The values resulting of all variables of the study were compared using ANOVA two-way. For the time factor, it was detected statiscal difference between groups in microtensile bond strength values (p=0,042), adhesive elastic modulus (p=0,000) and adhesive nanohardnes (p=0,000), the lowest values were observed in 6 months of storage. For adhesive factor, all groups presented statistical difference (p=0,000), except hybrid layer nanohardness (p=0,255). Clearfil properties (bond strength, modulus of elasticity of the adhesive and hybrid layer, nanohardness adhesive system and the hybrid layer) may vary depending on the adhesive system and time storage after the bonding procedures have been performed. Moreover, when an adhesive system presents a high elastic modulus of hybrid layer, it will present a high bond strength and low elastic modulus of adhesive layer.

Evaluation of Load Parameters and Hold Time of a Vickers Ultra-Micro Hardness Tester for Measure of Hardness and Modulus of Elasticity of Dental Composites

“…al. [19]; Bengtson [20] and EL-Safaty et al [13] observed that since the composite is a polymeric viscoelastic material formed by a heterogenic chemical structure, when the applied force is increased, the obtained results would become more stable and uniform, because with the increase of load and consequential depth of the penetrator it would be possible to reach every chemical component of said polymer. Hold time means the time spent waiting after the loading of the penetrator on the surface of the polymeric material and allows to monitor the possibilities of creep or mechanical stabilization of the material [21].…”

Influência do uso do digluconato de clorexidina como inibidor de metaloproteinase na resistência adesiva e dureza da camada híbrida e camada de adesivo

“…Os resultados demonstraram que os tratamentos com esses agentes foram capazes de aumentar a dureza e o módulo de elasticidade quando comparado aos grupos controle.Após a aplicação dos sistemas adesivos, foi confeccionado sobre essas superfícies de dentina tratada um bloco de resina composta Z-350 (3M ESPE, St.Paul, MN, USA) com auxílio de uma espátula de inserção nº 1 (Duflex) de 5mm de altura por meio da técnica incremental. A resina composta foi inserida em duas Dos corpos de prova obtidos, 5 palitos de cada grupo foram selecionados de forma aleatória e foram utilizados para mensuração da dureza da camada hibrida e camada de adesivo enquanto o restante de palitos foi utilizado para mensuração da resistência de união por meio de testes de microtração66 .…”