Faculty of Dentistry

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Browsing Faculty of Dentistry by Author "Fahmy, Nadia Zakria"

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    Assessment of Marginal Adaptation of Two CAD/CAM Glass Ceramic Occlusal Veneers at Different thickness After Thermodynamic aging
    (October university for modern sciences and Arts (MSA), 2022-07) Abouhagar, khaled Reyad; Salma, Aya Ahmed; Fahmy, Nadia Zakria
    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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    The Influence of Thermocycling on the Marginal Adaptation of Different Glass Ceramic Sectional Veneers
    (October university for modern sciences and Arts (MSA), 2022-07) Tantawy, Ahmed Amer; Fahmy, Nadia Zakria; Saad, Aya Ahmed
    Background: Sectional veneers constructed from different glass ceramic can show variations in the marginal adaptation before and after thermocycling. Methodology: 20 human central incisors were used to fabricate sectional laminate veneers SLV with preparation depth 0.5mm cervically and 0.7mm incisally. Samples were divided equally into groups according to material Group 1: Lithium disilicate Glass-Ceramic (IPS e-max press, Ivoclar, Schaan Liechtenstein) (n=10) and Group 2: zirconia reinforced lithium silicate Glass-Ceramic (Celtra Press, Dentsply Sirona) (n=10). SLV were bonded to the teeth using lightcure resin cement (Relyx veneer) (3M ESPE, Seefeld, Bayern, Germany). The samples were then subjected to 10,000 thermal cycles, the marginal adaptation was measured before and after thermocycling using stereomicroscope under magnification 40X using 8 measurement points for each margin (incisal, proximal, cervical and mid labial in two different positions) with total of 40 point per sample. Results: The results of ANOVA showed a significant interaction between material and thermocycling. Before thermocycling, e.max samples showed statistically significant higher gap values with (p<0.001) Mean and standard deviation (SD) values (34.80±0.71) than Celtra samples with (p<0.001) (26.33±2.28). While after thermocyling, Celtra samples had significantly higher gap values (53.77±6.67) than e.max samples (42.81±1.67). Conclusions: IPS e.max Press SLV showed better marginal adaptation compared to that of Celtra Press after thermocycling. Insufficient sealing between restoration and tooth may lead to leakage and marginal discoloration in sectional veneers after years of service. © 2022 MSA. All rights reserved. ∗ Corresponding author. E-mail address: drahmedamer@outlook.com 1 Master Degree in Faculty of Dentistry, October University for Modern Sciences and Arts 2 Professor of Fixed Prosthodontics, Faculty of Dentistry, October University for Modern Sciences and Arts 3 Lecturer of Fixed Prosthodontics, Faculty of Dentistry, October University for Modern Sciences and Arts