Abstract
The purpose of this study was to assess the influence of the types and thicknesses of glass ceramic plates on light transmittance and compare the degrees of conversion (DC) of resin cement under the ceramic materials. Three ceramic plates with thicknesses of 0.5, 1.0, 2.0, and 4.0 mm were fabricated from each of five commercial ceramic blocks in shade A2: high-translucency and low-translucency IPS Empress CAD (Emp_HT and Emp_LT); high-translucency and low-translucency IPS e.max CAD (Emx_HT and Emx_LT); and Vita Mark II (Vita). The translucency parameter was obtained using a colorimeter. The light transmittance rate was measured using a photodetector attached to an optical power meter. The DC of a resin cement (Variolink N) underneath the ceramic plates was examined by Fourier transform infrared spectroscopy. The translucency parameter, light transmittance rate, and DC showed significant differences by ceramic type and thickness (P < 0.05). The Emp_HT specimens showed the highest light transmission and DCs, and the Emx_LT showed the least light transmission and the lowest DCs. The high-translucency Empress showed significantly higher DCs than the low-translucency types (P < 0.05), but there was no significant difference in e.max (P > 0.05). Both type and thickness of the glass ceramics significantly influenced the light transmittance and DC of the light-cured resin cement beneath the ceramic of the same shade.
Highlights
The use of dental ceramics is increasing for restoring damaged, decayed, or missing teeth due to improvements in the physical properties of ceramics and advances in computer-aided design and computer-aided manufacturing (CAD/CAM) technology.[1,2,3] Dental ceramics for all-ceramic restorations can be classified into two main categories by their compositions: glassbased and crystalline-based.[4]
Monolithic ceramic blocks of all these glass-based ceramics are available as CAD/CAM restorative materials for clinicians to choose based on their desired restorations and mechanical and optical properties
Translucency types of Empress and e.max specimens showed This study evaluated the influence of ceramic type and thickness higher translucency parameter values than the low-translucency on the light transmittance rates and assessed the degrees of conversion (DC) of the lighttypes, and regardless of material, thicker specimens had lower cured resin cements beneath the ceramics
Summary
The use of dental ceramics is increasing for restoring damaged, decayed, or missing teeth due to improvements in the physical properties of ceramics and advances in computer-aided design and computer-aided manufacturing (CAD/CAM) technology.[1,2,3] Dental ceramics for all-ceramic restorations can be classified into two main categories by their compositions: glassbased and crystalline-based.[4]. A lithium disilicatereinforced glass ceramic (IPS Empress® II, called IPS e.max®), another enhanced glass-based ceramic, has gained popularity as a material for restoring anterior and posterior teeth from laminates, inlays, and onlays to single crowns due to its superior physical properties.[9,10] Monolithic ceramic blocks of all these glass-based ceramics are available as CAD/CAM restorative materials for clinicians to choose based on their desired restorations and mechanical and optical properties
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