The effect of endodontic access on all-ceramic crowns: A systematic review of in vitro studies.

Objectives: The aim of this systematic review was to identify from in vitro studies the effect of endodontic access on the fracture resistance and damage around the access cavity of all-ceramic crowns.

Data: The articles identified were screened by two reviewers according to inclusion and exclusion criteria. The reference lists of articles advanced to second round screening were hand searched to identify additional potential articles.

Endodontic access cavity simulation in ceramic dental crowns.

Objectives: It is proposed that a non-uniform rational B-spline (NURBS) based solid geometric model of a ceramic crown would be a flexible and quick approach to virtually simulate root canal access cavities. The computation of strain components orthogonal to surface flaws generated during the drilling would be an appropriate way of comparing different access cavity configurations.

Methods: A μCT scan is used to develop a full 3D NURBS geometric solid model of a ceramic crown.

The effect of variability in the powder/liquid ratio on the strength of zinc phosphate cement.

Aim. To investigate (a) variability in powder/liquid proportioning and (b) effect of variability on diametral tensile strength (DTS), in a zinc phosphate cement. Statistical analyses (α = 0.

Bonding auto-polymerising acrylic resin to acrylic denture teeth.

This study investigated the effect of surface treatments on the shear bond strength of an auto-polymerising acrylic resin cured to acrylic denture teeth. The surface treatments included a combination of grit-blasting and/or wetting the surface with monomer. Samples were prepared and then stored in water prior to shear testing.

Microhardness of resin composite materials light-cured through fiber reinforced composite.

Objectives: To compare polymerization efficiency of resin composite basing materials when light-cured through resin composite and fiber reinforced composite (FRC) by testing microhardness.

Methods: Simulated indirect restorations were prepared by application of resin composite (Clearfil AP-X) or FRC (EverStick) to nylon rings with 1.5mm thickness and 8mm diameter, followed by light-curing.

Surface microhardness of a nanofilled resin composite: a comparison of a tungsten halogen and a light-emitting diode light curing unit, in vitro.

Surface microhardness numbers (VHN) have been measured and compared for disk specimens (thickness 1.5 mm) of a commercial nanofilled resin composite cured using a range of exposure times with a quartz tungsten halogen (QTH) and light-emitting diode (LED) light-curing unit (LCU), respectively. Each LCU requires different minimum exposure times to optimise VHN with respect to the internal controls but yield bottom surface/top surface VHN ratios > 0.

Surface microhardness of a resin composite: a comparison of a tungsten halogen and a LED light curing unit, in vitro.

A comparison has been made between published surface microhardness numbers (VHN) of a commercial resin composite for different exposure times to a quartz tungsten halogen (QTH) and light-emitting diode (LED) light-curing unit (LCU). Both LCUs produced comparable hardness at both top and bottom surfaces, respectively, and similar bottom/top hardness ratios, for a specimen thickness of 1.5 mm, given sufficient exposure time (40 s) and an elapsed time of 24 h before measurement (for hardness numbers).

Early surface microhardness of a resin composite exposed to a pulse-delayed curing exposure: a comparison of a tungsten halogen and a plasma arc lamp, in vitro.

Surface microhardness numbers of a commercial resin composite have been compared after exposure to a quartz tungsten halogen (QTH) and plasma arc (PAC) lamp respectively, using two exposure protocols. The effect of increased tip-to-composite distance has also been compared. Exposure with the PAC lamp tested is more appropriate to the early finishing of composite restorations after placement and curing than with the QTH.

Surface microhardness of a resin composite exposed to a "first-generation" LED curing lamp, in vitro.

This investigation determined the minimum exposure times consistent with optimised surface microhardness parameters for a commercial resin composite cured using a "first-generation" light-emitting diode activation lamp. Disk specimens were exposed and surface microhardness numbers measured at the top and bottom surfaces for elapsed times of 1 hour and 24 hours. Bottom/top microhardness number ratios were also calculated.

In vitro study of surface microhardness of a resin composite exposed to a quartz-halogen lamp.

Objectives: To determine the minimum exposure times consistent with optimized surface microhardness numbers (VHN) for the top and bottom surfaces, respectively, of a resin composite (1.5-mm depth) cured using a quartz-halogen activation lamp. Additionally, to determine the conditions appropriate to achieve optimized bottom/top hardness ratios.

Surface microhardness of a resin composite exposed to pulse-delayed plasma arc lamp irradiation, in vitro.

Groups of samples of a light-activated resin composite were exposed, using a 3-step pulse-delayed protocol, to a plasma arc unit. Further groups were exposed with the light-curing guide positioned at increasing distances from the composite surface. The pulse-delayed protocol yielded a progressive increase in microhardness number at the end of each step but with a maximum mean value significantly less than the controls.