Howard W Roberts

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OBJECTIVE The purpose of this paper was to review the composition, properties, biocompatibility, and the clinical results involving the use of mineral trioxide aggregate (MTA) materials in endodontic treatment. METHODS Electronic search of scientific papers from January 1990 to August 2006 was accomplished using PubMed and Scopus search engines (search(More)
Resin-modified glass ionomers (RMGI) set by at least 2 mechanisms dependent upon reactant diffusion prior to gelation. Each reaction's kinetics and setting mechanism may rely on and/or compete with the other. In this study, we investigated RMGI setting reaction interactions using differential scanning calorimetry (DSC) by varying light-cure initiation(More)
PURPOSE The purpose of this study was to compare the curing efficiency of three commercially available light-emitting diode (LED)-based curing lights with that of a quartz tungsten halogen (QTH) curing light by means of hardness testing. In addition, the power density (intensity) and spectral emission of each LED light was compared with the QTH curing light(More)
PURPOSE The aim of this study was to examine the influence of light guide type on the distribution of irradiant emission from a light-emitting diode (LED) curing light and to measure the effect of light dispersion on surface microhardness across the top and bottom surfaces of two types of composite resins. MATERIALS AND METHODS A laser beam analyzer(More)
PURPOSE To determine the accuracy of commercially available, handheld light-emitting diode (LED) and halogen-based radiometers using LED and quartz-tungsten-halogen (QTH) curing lights with light guides of various diameters. METHODS The irradiance of an LED curing light (L.E. Demetron 1, SDS/Kerr, Orange, CA, USA) and a QTH curing light (Optilux 501,(More)
STATEMENT OF PROBLEM A luting cement must maintain a minimum film thickness over a sufficient period of time to allow seating of indirect restorations. The performance of newer luting cements in this regard has not been evaluated. PURPOSE The purpose of this study was to compare the film thicknesses of 6 luting cements, 2 resin-modified glass ionomer(More)
INTRODUCTION Novel nickel-titanium rotary files with proprietary manufacturing techniques have recently been marketed. The purpose of this study was to assess multiple autoclave cycle effects on cyclic fatigue of GT Series X files (Dentsply Tulsa Dental Specialties, Tulsa, OK) and Twisted Files (SybronEndo, Orange, CA) METHODS: A jig using a 5-mm radius(More)
BACKGROUND Elucidating the microstructural responses of the lithium disilicate system like the popular IPS e.max® CAD (LS2), made specifically for computer-aided design and computer-aided manufacturing (CAD-CAM), as a temperature-dependent system unravels new ways to enhance material properties and performance. OBJECTIVE To study the effect of various(More)
INTRODUCTION The aim of this study was to evaluate NaOCl apical extrusion by using negative apical pressure (EndoVac), sonic agitation (EndoActivator), side-vented needle (Max-i-Probe), and photon induced photoacoustic streaming (PIPS 10 mJ and PIPS 20 mJ) laser irrigation in an in vitro gel model. METHODS Extracted mandibular and maxillary central(More)
STATEMENT OF THE PROBLEM The polymerization of bulk-placed resin-modified glass-ionomer (RMGI) restoratives is compromised when penetration of the curing light is limited because of the materials' thickness. It is unknown if additional post light-curing resin polymerization and/or glass-ionomer setting occurs over time to ensure adequate polymerization. (More)