Mechanical Properties of Hard Resins for Crowns and Bridges

Abstract

Two types of hard resin for crowns and bridges were investigated. The results of each investigation changed according to the products used, and the proper use for each case and application was suggested. AbstractPurpose: Hard resins for crowns and bridges are wide ly used for esthetic restorations. The objective of this study was to evaluate the mechanical properties of new commercial hard resins and to compare the results with those of the other hard resins previously investigated. Methods:Dentin and enamel made with two new hard resins (Epricord ® : EP, Kuraray, Co., Ltd., Osaka, Japan and Prossimo ® : PR, GC, Co., Ltd., Tokyo, Japan) were used in this study. Regarding the fundamental charac teristics, the thermal expansion/shrinkage coefficient, the filler content, the polymerization shrinkage, and the wear were examined. Regarding the strength of resin, the bending strength, hardness, compression strength, elastic modulus, and fracture strength of a jacket crown were measured.Results: These resins showed comparatively lower lev els than the other hard resins regarding the bending strength, hardness, compression strength, and fracture strength of the jacket crown. The total filler content rate and wear amount of these resins exhibited similar values to those of the other resins. The thermal expan sion/shrinkage coefficients of these resins exhibited higher values than those of the other resins. EP showed a different tendency from PR about the compression strength, elastic modulus, and polymerization shrink age.Conclusions: PR and EP did not show dramatically better physical properties. However, the results of each examination in this study may be acceptable clinically.The results of each investigation changed according to the products used, and proper use for each case and ap plication was suggested.Key words: hard resin for crown and bridge, mechani cal property, resin facing cast crown, resin jacket crown

Influence of laboratory light sources on the wear characteristics of indirect composites

“…Both materials were designed for indirect restorations and fixed partial dentures. Estenia C&B was composed of approximately 12% methacrylate monomers and 87.9% filler 30) , while Epricord was approximately 24% methacrylate monomers and 76.0% filler 31) . Shade E1 for the enamel portion was used for specimen preparation.…”

“…The mean value of eight replications, with pause intervals of five minutes, was calculated for two wavelength ranges: 400-500 nm and 200-800 nm. In particular, the visible light wavelength range of 400-500 nm was reportedly effective for the polymerization of camphorquinone-initiated dental composites 31) .…”

Effect of Storage Time on Bond Strength Performance of Multimode Adhesives to Indirect Resin Composite and Lithium Disilicate Glass Ceramic

“…The demand for esthetic metal-free dental treatments such as inlays, onlays, veneers, and crowns has increased in recent years, which has contributed greatly to the development of adhesive cementing systems for ceramic and indirect resin composite restorations. [1][2][3][4][5] The indirect restorative procedure involves the creation of a machined or laboratoryfabricated restoration, followed by adequate conditioning of the tooth and indirect restoration, and then placement of the restoration with a resin cement. 6 Unlike that with the direct technique, the indirect method can be used to restore the mechanical and biological functions of the tooth with minimal intraoral polymerization shrinkage; 7 this can provide better control of the contact and contour of proximal restorations 8 and therefore enhances the marginal adaptation of the restorative material in the long term.…”

Fracture force for veneered materials on restorations measured by torsion testing

“…In shearing tests, there is a stress concentration at the weighted side. The stress distribution in torsion tests with a square bar shows an increase from a stress value of 0 at the center to the maximum value at the outer edge due to the action of the torque 30) . For this reason, in the plate shape used in the present study, the fixed side and the outer edge of the rotating side showed a greater stress concentration.…”