A preliminary survey of impression trays used in the fabrication of fixed indirect restorations.

Purpose: A variety of impression trays are used in the fabrication of fixed indirect restorations. Impressions used in the construction of fixed indirect restorations were examined for tray type, manner of use, and overall impression quality.

Materials And Methods: A commercial dental laboratory provided 1403 impressions used to fabricate fixed indirect restorations during a 3-month period.

Hardness and wear resistance of two resin composites cured with equivalent radiant exposure from a low irradiance LED and QTH light-curing units.

Purpose: To measure and compare three-body wear and Vickers hardness at depths of 0 mm and 2 mm in two composite resin materials cured with either a low irradiance light emitting diode (LED) or a quartz tungsten halogen (QTH) light-curing unit (LCU) in which exposure duration with the LED was increased to deliver equivalent radiant exposure in the 450-490 nm wavelength range.

Methods: The VIP QTH and Freelight LED LCU's were obtained and the emission spectrum of each was determined using a Spectra Pro 750 spectrograph. Irradiance in the 450-490 nm range for each LCU was determined by calculating the area under the spectral curve.