Restoration of anterior teeth requires high precision in the shade selection of the restorative material due to its aesthetic appearance. Incorrect selection of shade for the restoration may result in patient's dissatisfaction due to... more
Restoration of anterior teeth requires high precision in the shade selection of the restorative material due to its aesthetic appearance. Incorrect selection of shade for the restoration may result in patient's dissatisfaction due to unaesthetic appearance. This study was conducted to determine the optimum lighting condition and preferable patient's position that may influence the anterior tooth shade selection at the Faculty of Dentistry, Universiti Kebangsaan Malaysia. One hundred dental students from the 4th and 5th year were randomly selected to perform the shade selection procedure on the maxillary central incisor of two selected subjects. The shade of the tooth was predetermined using an intraoral spectrophotometer machine and the result was used as reference for the visual shade selection procedure done by the students. Four different clinical situations were selected and the shade selected by the students' was compared with the predetermined shade. The result showed that the shade selection for anterior composite resin restoration is more reliable using the first reading taken (46%) when the patient is in the upright position (35.5%) with dental chair light off (56%). As a conclusion, the patient's position, lighting condition and number of readings taken does influence the result of the shade selection for the anterior tooth.
Objective. The aim of this study was to evaluate long-term fatigue behavior using an in vitrostep-stress accelerated life test (SSALT), and to determine the crack initiation point usingin silico finite element analysis for computer-aided... more
Objective. The aim of this study was to evaluate long-term fatigue behavior using an in vitrostep-stress accelerated life test (SSALT), and to determine the crack initiation point usingin silico finite element analysis for computer-aided designed and manufactured (CAD/CAM)molar crowns fabricated from three commercial CAD/CAM resin composite blocks: Ceras-mart (CS; GC, Tokyo, Japan), Katana Avencia Block (KA; Kuraray Noritake Dental, Niigata,Japan), and Shofu Block HC (HC; Shofu, Kyoto, Japan).Methods. Fifty-one mandibular first molar crowns luted on a resin core die were embeddedin acrylic resin and covered with a polyvinyl chloride tube. Single compressive tests wereperformed for five crowns. SSALT was conducted for 36 crowns using three profiles andreliabilities at 120,000 cycles, and a Weibull analysis was conducted. The maximum principalstrain of each CAD/CAM resin composite crown model was analyzed by three-dimensionalfinite element analysis.Results. Fracture loads of CS and KA (3784 ± 144 N and 3915 ± 313 N) were significantly greaterthan that of HC (2767 ± 227 N) (p < 0.05). Fracture probabilities at 120,000 cycles were 24.6%(CS), 13.7% (KA), and 14.0% (HC). Maximum principal strain was observed around the mesi-olingual cusps of CS and KA and the distobuccal cusp of HC.Significance. CAD/CAM resin composite molar crowns containing nano-fillers with a higherfraction of resin matrix exhibited higher fracture loads and greater longevity, suggestingthat these crowns could be used as an alternative to ceramic crowns in terms of fatiguebehavior.
Aim: This study was designed to evaluate the microhardness, diametral tensile strength and compressive strength of a nano-filled glass ionomer restorative material in comparison with a resin modified and conventional glass ionomers.... more
Aim: This study was designed to evaluate the microhardness, diametral tensile strength and compressive strength of a nano-filled glass ionomer restorative material in comparison with a resin modified and conventional glass ionomers. Materials and Methods: A total of 45 specimens were prepared from three types of glass ionomer restorative materials. Specimens were cured with a light curing unit according to the manufacturer’s instructions. The specimens were prepared using Teflon split molds with dimensions of 6 mm height and 4 mm diameter. Incremental curing in 3 layers, 2mm each were used. After curing, all specimens were immersed in distilled water for 24 hours. Microhardness test was done using a Vickers microhardness Tester with 25 gf load for 5 sec. Diametral tensile strength and compressive strength were measured using Intestron testing machine at cross-head speed of 50 gm/sec until fracture. Results: There was a significant difference among the tested materials in all testing parameters. Ketac fil Aplicap exhibited the highest hardness value while Glass carbomer fil GCP has the lowest value while GC Fuji II LC showed intermediate micro-hardness value. GC Fuji II LC exhibited the highest diametral tensile and compressive strength values while Ketac Fil Plus Aplicap has the lowest values. Glass Carbomer Fil, GCP showed intermediate diametral tensile and compressive strength values. Conclusions: The nano-filled glass ionomer (Glass Carbomer Fil, GCP) exhibited the lowest hardness value, intermediate diametral tensile and compressive strength values.
Restoration of anterior teeth requires high precision in the shade selection of the restorative material due to its aesthetic appearance. Incorrect selection of shade for the restoration may result in patient’s dissatisfaction due to... more
Restoration of anterior teeth requires high precision in the shade selection of the restorative material due to its aesthetic appearance. Incorrect selection of shade for the restoration may result in patient’s dissatisfaction due to unaesthetic appearance. This study was conducted to determine the optimum lighting condition and preferable patient’s position that may influence the anterior tooth shade selection at the Faculty of Dentistry, Universiti Kebangsaan Malaysia. One hundred dental students from the 4th and 5th year were randomly selected to perform the shade selection procedure on the maxillary central incisor of two selected subjects. The shade of the tooth was predetermined using an intraoral spectrophotometer machine and the result was used as reference for the visual shade selection procedure done by the students. Four different clinical situations were selected and the shade selected by the students’ was compared with the predetermined shade. The result showed that the...
The aim of this study was to build an in silico computer-aided design and computer-aided manufacturing (CAD/CAM) resincomposite-block (RCB) model with different silane coupling ratios and to evaluate the physical and mechanical properties... more
The aim of this study was to build an in silico computer-aided design and computer-aided manufacturing (CAD/CAM) resincomposite-block (RCB) model with different silane coupling ratios and to evaluate the physical and mechanical properties of the models, including the elastic modulus, Poisson’s ratio, compressive strength, and maximum principal strain. Nanoscale CAD/CAM RCB models were designed by using CAD software that consisted of twelve spherical silica nanofiller particles and a resin matrix. Seven nanoscale models with different silane coupling ratios were prepared with the same filler volume contents. Homogenization analysis was conducted by using voxel-base finite-element analysis software to predict the elastic moduli and Poisson’s ratio of the macro CAD/CAM RCB. Localization analysis was used to analyze the maximum principal strain distribution in the hydrolysis layer. In silico multi-scale analysis demonstrated that the compressive strength of the CAD/CAM RCB was reduced with a decrease in the silane coupling ratios of the fillers.
