Background: Occlusal veneers fabricated with different materials and thicknesses can reveal different marginal adaptation after thermodynamic aging.Methodology: Extracted maxillary premolar teeth (n=28) were collected and embedded in epoxy resin block with light body material then randomized according to materials into two groups (n=14): Lithium disilicate IPS e.max CAD (A) and Zirconia reinforced lithium silicate Celtra Duo (B) then further randomized into four subgroups (n=7) according to occlusal veneer thicknesses 1 mm and 1.5 mm. Teeth were prepared by a customized milling machine then the exposed dentine was immediately sealed by dentine bonding agent. Fabrication of the occlusal veneers was done by CAD/CAM milling machine. Occlusal veneers were adhesively cemented by dual cure resin cement (Panavia F 2.0). All samples were subjected to thermocycling and cyclic loading equivalent to one year of service (150,000). Marginal gap measurements then were done with A digital microscope at 35x magnification was used to photograph each specimen. Marginal gap was measured and evaluated using a computerized image analysis system.Results: two-way ANOVA showed that the materials only IPS e.max CAD (39.30±5.14) had significantly higher value than Celtra Duo (31.52 ± 5.69) (p<0.001).While regarding the thicknesses 1 mm thick samples (36.78 ± 6.06) had significantly higher value than 1.5 mm thick samples (34.04 ± 7.02) (p=0.020). Conclusion:Zirconia reinforced lithium silicate (Celtra DUO) occlusal veneers showed better marginal adaptation than lithium disilicate (IPS e.max CAD) in different thicknesses. Zirconia reinforced lithium silicate (Celtra DUO) marginal adaptation was influenced by occlusal veneer thickness (the thicker 1.5 mm showed better adaptation than 1mm.

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Background:The purpose of this study is to evaluate the effect of two glass ceramic materials and resin cement curing modes on the color stability of sectional porcelain laminate veneers following artificial aging. Methods: Forty sound human maxillary central incisors were prepared to receive sectional laminate veneers (SLVs) with a thickness of 0.5-0.7 mm. Prepared teeth were randomly divided into 2 equal groups according to ceramic materials used (N=20) as follows: Group I: IPS e.max press. Group II: Celtra press. Each main group was randomly subdivided into 2 equal subgroups according to resin cement used: light and dual cure resin cements (Relyx Veneer) (Relyx Ultimate) respectively. All samples were subjected to 10,000 cycles of thermo-cycling. Color change was measured by laboratory spectrophotometer before and after thermocycling. All the collected data were statistically analyzed by One-way ANOVA followed by Tukey's post hoc test. Results: Color change between restoration and natural side of each sample before and after artificial aging did not reveal significant difference (P<0.05). IPS e.max press showed significant lower color stability with dual and light cure resin cement (ΔE 3.48-ΔE 3.4) than Celtra press (ΔE 2.6-ΔE 3.05). Light cured resin cement used with Celtra press showed statistically significant higher ΔE value than dual cured cement (P>0.05). Conclusions: Celtra press glass ceramic is more color stable than IPS e.max press. Resin cement and aging process influenced the color stability of sectional laminate veneers. Results were clinically accepted for all tested materials in reference to natural teeth (ΔE<3.5). The results may help the patient to aesthetically correct their anterior teeth with a suitable material providing strength and natural teeth looking, in addition to conservation of tooth structure, with optimum esthetics.