Objective: This study measured the color change of lithium disilicate (E. max CAD), microhybrid resin composite (Coltene C bright, Filtek Z250) and feldspathic ceramic (Vita Mark II) laminates after putting them in coffee, Cola and artificial saliva staining solutions for seven days.Materials and Methods: Sixty freshly extracted sound upper central incisors were randomly divided into four groups (n=15) according to the material used for laminate veneer fabrication; E. max CAD (Group I), VitaMark II (Group II), Coltene C Bright blocks (Group III) and Filtek Z250 composite resin (Group IV). Teeth were all prepared to receive a prepared sample of a squared-shaped laminate of different materials in a dimension of 7x7 mm. Cementation, finishing and polishing procedures were performed followed by color change measurement using a spectrophotometer. Measurements were all recorded before and after immersion for seven days.Results: Time, material type and immersion medium had a statistically significant effect on mean color change (p<0.001). Intra-group comparisons displayed that E. max CAD showed the lowest color change, whereas Coltene C bright blocks were the greatest to show color change. Vita Mark II showed a higher color change in artificial saliva than Filtek Z250, however, the latter demonstrated a surpassing change in color in the other solutions. Conclusion:Material type, external source of stain, and staining time are important factors that affect the degree of color change, which in turn could affect patient satisfaction. E. max showed the best results in all solutions regardless the exposure time.

Statement of the Problem:The fracture of the veneering material of any bi-layered fixed restoration is a decisive factor. Recently developed PEEK has gained an attention in being used in the oral cavity as a fixed partial denture framework. However, deciding whether PEEK restoration will withstand function and retain its form is still under investigation.Introduction; PEEk which is basically a result when manufacturer included ceramic filler particles in its matrix BioHPP, making it a suitable polymer to be used as a temporary and permanent restorations. To test whether this new BioHPP will withstand the function in the oral cavity, in terms of wear and volumetric loss, and determine its efficacy as permanent or final restoration.Materials and Methods; 30 BioHPP discs, apposing human enamel and lithium disilicate and zirconia six millimeter hemispheres, were tested in a dual axis chewing simulator. The number of cycles was 120,000 corresponding to six months intra-orally. Then the specimens were scanned pre and post testing, and volume was evaluated using Geomagic qualify software.Results; There was a statistically significant difference between volume loss in the three groups (P-value = 0.003, Effect size = 0.361). Pair-wise comparisons between the groups revealed that enamel showed the statistically significantly highest mean volume loss whereas L. Zirconia showed lower mean value and Lithium Disilicate showed the lowest mean weight loss. Conclusion;BioHPP is a convenient material to use intra orally in a monolithic form, its also expected to cause less wear than most used ceramics.

Background: CAD/CAM Composite is one of the esthetic milled restorations. It has high esthetic properties and modulus of elasticity close to that of dentin. The color stability of composite CAD/CAM restorations is still under investigation. Aim: To evaluate the color stability of milled nano-hybrid composite and hybrid ceramic compared to lithium disilicate after Artificial Accelerated Aging. Materials and Methods: Twenty seven disc-shaped samples (10mm X 2mm) were fabricated in standardized manner. Samples were divided into three equal groups (n=9) according to the material type: Lithium disilicate ceramic (IPS e.max CAD), Hybrid Ceramic (Vita Enamic) and Nano-hybrid CAD/CAM composite (Tetric CAD). Color measurements of the three milled materials were assessed before and after Artificial Accelerated Aging (AAA) in weathering machine for 300 hours using a spectrophotometer based on CIE L*a*b* relative to the standard illumination D65. Color difference was obtained by calculating the difference in color measurements of the specimens before and after accelerated aging using the formula ∆E=[(∆L*) 2 +(∆a*) 2 +(∆b*) 2 ] ½ . Results: There was a statistically significant difference between ΔE of different ceramic types. Tetric CAD showed the highest mean DE (4.29) while there was no statistical significance difference between Vita Enamic and IPS e.max CAD (3.02 and 2.94 respectively). Conclusion: Artificial accelerated aging caused clinically unacceptable color changes in Tetric CAD, while it caused perceptible but clinically acceptable color changes in Vita Enamic and IPS e.max CAD. Color changes after artificial aging is related to the chemical composition of the material.