The aim of this study was to evaluate the polymerization shrinkage and shrinkage stress of composites polymerized with a LED and a quartz tungsten halogen (QTH) light sources. The LED was used in a conventional mode (CM) and the QTH was used in both conventional and pulse-delay modes (PD). The composite resins used were Z100, A110, SureFil and Bisfil 2B (chemical-cured). Composite deformation u...

The existence of a formal analogy between quantum energy spectra and discrete time series has been recently pointed out. When the energy level fluctuations are described by means of the n statistic, it is found that chaotic quantum systems are characterized by 1/ f noise, while regular systems are characterized by 1/ f2. In order to investigate the correlation structure of the n statistic, we s...

Aim The aim of this study is to compare and to evaluate effect of curing light and curing modes on the nanohybrid composite resins with conventional Bis-GMA and novel tricyclodecane (TCD) monomers. Methodology Two nanohybrid composites, IPS empress direct and charisma diamond were used in this study. Light-emitting diode (LED)-curing unit and quartz-tungsten-halogen (QTH)-curing unit which we...

BACKGROUND Modern dental composite restorations are wholly dependent on the use of Visible Light Curing devices. The characteristics of these devices may influence the quality of composite resin restorations. OBJECTIVE To determine the characteristics of light curing units (LCUs) in dental clinics in Nairobi and their effect on light intensity output, depth of cure (DOC) and surface micro-har...

This study compared the compressive strength of a composite resin and compomer photoactivated with a conventional quartz-tungsten halogen-light (XL 3000, 3M/SPE) and a blue light-emitting diode (LED) (SmartLite PS; Dentsply/De Trey). Forty disc-shaped specimens were prepared using a split polytetrafluoroethylene matrix (4.0 mm diameter x 8.0 mm hight) in which the materials were inserted increm...

PURPOSE Adequate polymerization is a crucial factor in obtaining optimal physical properties and a satisfying clinical performance from composite resin materials. The aim of this study was to evaluate the polymerization efficiency of dual-cure resin cement cured with two different light curing units under zirconia structures having differing thicknesses. MATERIALS AND METHODS 4 zirconia discs...

The aim of this study was to evaluate the effects of different light-curing units and resin cement curing types on the bond durability of a feldspathic ceramic bonded to dentin. The crowns of 40 human molars were sectioned, exposing the dentin. Forty ceramic blocks of VITA VM7 were produced according to the manufacturer's recommendations. The ceramic surface was etched with 10% hydrofluoric aci...

OBJECTIVES The aim of this study was to determine the effect of ageing on the light intensity of quartz-tungsten-halogen (QTH) polymerization units in dental schools and dental clinics. MATERIALS & METHODS Two dental schools and multiple public health dental clinics were visited and the light intensity of curing units was assessed. The age, make, model and service history were recorded. A cal...

OBJECTIVE This study evaluated the surface hardness of a resin cement (RelyX ARC) photoactivated through indirect composite resin (Cristobal) disks of different thicknesses using either a light-emitting diode (LED) or quartz tungsten halogen (QTH) light source. MATERIAL AND METHODS Eighteen resin cement specimens were prepared and divided into 6 groups according to the type of curing unit and...

ceramic on light transmission of light-emitting diode (LED) and quartz-tungsten-halogen units (QTH) were evaluated. Ceramic IPS e.max CAD shades A1, A2, A3, A3.5, high (HT) and low (LT) translucency were cut (1, 2, 3, 4 and 5 mm). Light sources emission spectra were determined. Light intensity incident and transmitted through each ceramic sample was measured to determine light transmission perc...