OBJECTIVES To evaluate the shrinkage-strain, degree of conversion (DC) and percent filler of a range of flowable resin-composites. METHODS Several commercially available flowable resin-composites were selected. The bonded-disk technique was used to measure shrinkage-strain kinetics. Measurements were obtained continuously for 60min by irradiation for 40s at 750mW/cm(2) at two initial temperat...

OBJECTIVES To test the null hypotheses that photoactive resin composites containing a Type I photoinitiator would exhibit reduced DC or increased monomer elution at substantially short curing times compared with materials based on a Type 2 ketone/amine system. METHODS Two experimental resin composites were prepared, using either Lucirin-TPO or camphorquinone/DMAEMA. Specimens were light-cured...

introduction: resin composites are an important part of restorative treatment in modern dentistry. there are many trademarks available in iran market and physico-chemical properties of many of these resin composites are not evaluated yet. this study was carried out to evaluate the physico-chemical properties of four available resin composites and also to assess the effect of aging on their prop...

The aluminum bronze matrix alumina composites using hot press and resin infiltration were investigated to study their porosities, hardness, bending strengths, and microstructures. The experiment results show that the hardness of the sintered composites with the decrease of porosity increases. The composites without and with resin infiltration have about HRF 42-61 of about 34-40% of porosity and...

condensation reaction of urea, casein and formaldehyde in the presence of varying proportion of resorcinol under alkaline condition. All the prepared resins were characterized by free-formaldehyde content, free-phenol content, viscosity measurements and infrared spectroscopy (IR). The resin samples were cured isothermally at 120oC using two different curing agents, p-toluene sulphonic acid (PTS...

The resin flow behavior in the vacuum assisted resin infusion molding process (VARI) of foam sandwich composites was studied by both visualization flow experiments and computer simulation. Both experimental and simulation results show that: the distribution medium (DM) leads to a shorter molding filling time in grooved foam sandwich composites via the VARI process, and the mold filling time is ...

Resin composites were first introduced as anterior restorative materials, but are more and more used in posterior teeth, as amalgam replacements. Nowadays the so-called ‘condensable’ composites are frequently used in posterior teeth. These materials are subjected to high values of contact and mastigatory loads, loading rates and sliding distances. In such contact conditions, wear is the major f...

OBJECTIVES Adhesion of resin composites to dentin is currently believed to result from impregnation of adhesive resin into superficially demineralized dentin. The purpose of this study was to use micro-Raman spectroscopy and scanning electron microscopy (SEM) to investigate the extent of resin penetration into etched dentin with single-step adhesive systems. METHODS Adhesive systems used were...

OBJECTIVE To compare the performance and postoperative sensitivity of a posterior resin composite with that of bonded amalgam in 40 (n = 20) large sized cavities and to evaluate whether resin composite could be an alternative for bonded amalgam. MATERIALS AND METHODS This was a randomized clinical trial. Twenty patients in need of at least two posterior restorations were recruited. Authors ra...

Natural fibers can be attractive reinforcing materials in thermosetting polymers due to their low density and high specific mechanical properties. Although the research effort in this area has grown substantially over the last 20 years, manufacturing technologies to make use of short natural fibers in high volume fraction composites; are still limited. Natural fibers, after retting and preproce...