OBJECTIVES Aim of the study was to analyze the mold filling capacity and the dimensional accuracy of a spinel-based investment for titanium castings. METHODS Expansion of the investment in dependence of the preheating temperature was measured in a dilatometer. The degree of transformation of MgO and Al2O3 to spinel (MgAl2O4) was evaluated by means of X-ray powder diffraction. Mold filling cap...

STATEMENT OF THE PROBLEM Issues regarding the use of composite preheating need to be investigated so that the clinician will better understand the variables associated with this method. PURPOSE To examine the multiple aspects of use of a commercial composite preheating device (Calset, AdDent Inc., Danbury, CT, USA). MATERIALS AND METHODS Temperature values of three heating units and composi...

OBJECTIVES The purpose of this study was to compare the flexural strength and modulus of two commercial resin composites, at room temperature and 40, 45 and 50 degrees C prior to light polymerization with standard and step-cure protocols. METHODS One nanohybrid (Grandio, VOCO, Cuxhaven, Germany), and microhybrid composite resin (Filtek Z250, 3M ESPE, St. Paul, MN, USA) were used. The material...

We study preheating in DBI hybrid inflation. Preheating occurs since the matter fields are non-minimally coupled to the inflaton. Despite the coupling being small, preheating happens as a narrow parametric resonance in which matter fields and inflaton modes are exponentially created. We show that, within the approximations used, the process is very efficient at late times. The resonance stage g...

The ASTM F-75 (Co-28%Cr-6%Mo) is widely used as a biocompatible alloy in medicine for manufacturing implants. In this study, effect of mold preheating on the as-cast microstructure of the alloy was investigated using the solid investment casting process. Several mold preheating temperatures of 550, 700, 850 and 1000 °C were selected at the same melt superheat. The samples were characterized by ...

A microwave (MW) preheating mechanism of anisotropic conductive adhesive film (ACF) has been introduced in order to reduce the bonding temperature for flip chip technology. Thermal curing of epoxy shows a very sluggish and non-uniform curing kinetics at the beginning of the curing reaction, but the rate increases with time and hence requires higher temperature. On the other hand MW radiation ha...

OBJECTIVE The aim of this study is to evaluate the effect of composite preheating and polymerization mode on degree of conversion (DC), microhardness (KHN), plasticization (P), and depth of polymerization (DP) of a bulk fill composite. METHODS Forty disc-shaped samples (n = 5) of a bulk fill composite were prepared (5 × 4 mm thick) and randomly divided into 4 groups according to light-curing ...

Background. One of the problems with composite resin restorations is gap formation at resin‒tooth interface. The present study evaluated the effect of preheating cycles of silorane- and dimethacrylate-based composite resins on gap formation at the gingival margins of Class V restorations. Methods. In this in vitro study, standard Class V cavities were prepared on the buccal surfaces of 48 bovin...

BACKGROUND AND OBJECTIVES Although cryogen spray cooling (CSC) in conjunction with laser therapy has become the clinical standard for treatment of port wine stain (PWS) birthmarks, the current approach does not produce complete lesion blanching in the vast majority of patients. The objectives of this study are to: (1) experimentally determine the dynamic CSC heat flux when a skin phantom is pre...