background and aims. today light cured composites are widely used. physical and mechanical properties of composites are related to the degree of conversion. light curing unit (lcu) is an important factor for composite polymerization. aim of this study is evaluation of composite resins hardness using halogen and led light curing units. materials and methods. in this study, 30 samples of filtek z...

objectives: this study aimed to compare the shear bond strength (sbs) of composite to stainless steel crowns (ssc) using two mechanical surface treatments (msts) and two bonding systems. materials and methods: eighty-four sscs were divided into six groups of 14; group1: no mst+scotchbond universal adhesive (n+u), group 2: surface roughening by a diamond bur+scotchbond universal adhesive (r+u), ...

objective: various techniques of composite placement have been used to decrease microleakage around the composite restorations. due to controversial results, the present study was conducted to investigate the effect of different placement techniques on microleakage in class v composite restorations. materials and methods: sixty class v cavities were prepared on the buccal and lingual surfaces o...

microleakage is a major factor affecting longevity of composite restorations. this study evaluated the effect of polymerization mode of bonding agent on microleakage of composite restorations.forty-eight class v cavities were prepared on buccal and lingual surfaces of 24 extracted human premolars. occlusal and gingival margins were placed in the enamel and dentin, respectively. teeth were divid...

OBJECTIVES This study examined the color changes of a resin composite with different shades upon exposure to water with different pH. MATERIALS AND METHODS Nanohybrid resin composites (Filtek Z350XT, 3M ESPE) with four different shades (A2, A3, B1, and B2) were immersed in water with three different pH (pH 3, 6, and 9) for 14 day. The CIE L*a*b* color coordinates of the specimens were evaluat...

The manufacturers of some condensable posterior composites claim that their products can be placed in bulk and light-cured in 5-mm-thick increments. This study compared the shear bond strengths of three composite resins when bonded to dentin in 2- and 5-mm-thick increments. Overall the bond strengths were adversely affected by the composite thickness (p < 0.0001). The shear bond strength of eac...

BACKGROUND With the increase in demand for cosmetics and esthetics, resin composite restorations and all-ceramic restorations have become an important treatment alternative. Taking into consideration the large number of prosthodontic and adhesive resins currently available, the strength and durability of these materials needs to be evaluated. This laboratory study presents the shear bond streng...

This study evaluated the effects of acidic medicines (Dimetapp and Claritin), under pH-cycling conditions, on the surface degradation of four composite resins (microhybrid: TPH, Concept, Opallis and Nanofilled: Supreme). Thirty disc-shaped specimens ([symbol: see text] = 5.0 mm/thickness = 2.0 mm) of each composite were randomly assigned to 3 groups (n = 10): a control and two experimental grou...

Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, includin...

Low cost composite materials are widely used in civil and structural engineering applications. This project uses EPON to plasticize a commonly used resin, epoxy resin to lower the cost of the composite and to find out the mechanical and thermal properties of the plasticized epoxy resin to see if it is suitable for the said applications. Three point bending tests were carried out to evaluate the...