Mostafa Ahmad Abd El Atif Eldessouky

Mohammed Moustafa Shalaby

01/01/2020

Mostafa Ahmad Abd El Atif Eldessouky

Rania A Amin; Dalia A Saba

01/04/2019

Mostafa Ahmad Abd El Atif Eldessouky

Reem Gamal, Yasser F.Gomaa

01/12/2017

Aim of the study This in vitro study was conducted to evaluate the microtensile bond strength (μTBS) of surface treated zirconia bonded to dentin specimens using two aged contemporary dual cured self-adhesive resin cements. Materials and methods Sixty cuboidal-shaped zirconia ceramic specimens were obtained using CAD/CAM system. Specimens were divided into two equal main groups; 30 specimens each, gp A in which specimens did not receive any further surface treatment & gp B in which only one surface of each specimen was airborne abraded. Each group was then divided into two equal groups; 15 each, according to the type of adhesive resin cement used for bonding zirconia specimens to ground flat dentine surfaces; RelyX™ U200 (cement I) and Multilink® Speed (cement II). The assemblies were further subdivided into 3 equal subgroups; 5 assemblies each, according to aging protocol. The aging protocols were storage in distilled water for 1 day, for 7 days without thermocycling and for 7dayes followed by thermocycling; subgroups 1, 2 and 3 respectively. After aging, the assemblies were sectioned into beams approximately 1 mm2 in cross section resulting in 25 beams for each subgroup; 20 of them were selected for μTBS (n = 20) and 5 were kept for SEM examination. Results Group B showed statistically significantly higher mean micro tensile bond strength value than group A. The type of cement had statistically insignificant effect on mean micro tensile bond strength. Thermocycling significantly reduced μTBS of both cements bonded to untreated zirconia ceramic; IA3 and IIA3 subgroups. For SEM, cement I showed gaps at its interface with zirconia groups A and B regardless of aging protocol. Cement II showed only gaps at its interface with zirconia ceramic group A only but good adaptation appeared at its interface with zirconia ceramic group B for aged for 1 day (subgroup IIB1) and 7 days without thermocycling (subgroup IIB2). However, cement II bonding air abraded zirconia ceramic followed by thermocycling (subgroup IIB3) showed both gap free as well as gap containing areas at high magnification only. Conclusions Airborne abrasion-surface treatment of zirconia significantly enhanced the μTBS of both cements adhered to dentin while aging had an adverse effect. MS showed higher insignificant μTBS.

Mostafa Ahmad Abd El Atif Eldessouky

Osama Saleh, Rania A. Amin, Mostafa A. Abdellatif

01/01/2016

Purpose: The purpose of this study was to evaluate the effect of pattern construction technique on the marginal accuracy, internal fitness and fracture resistance of E-max crowns. Materials and methods: Thirty caries-free human maxillary first premolars were selected, cleaned by scaling, and stored in 0.9% standardized saline solution at room temperature. Using an industrial lathe machine, the teeth were prepared to receive all ceramic crowns with standardized dimensions of 6 degrees angle of convergence. The preparation had 5mm occluso-cervical height, 6mm cervical diameter and 1 mm deep chamfer finish line. The prepared teeth were divided into three groups (n=10) according to the pattern fabrication techniques used: Group1: Conventional wax patterns. Group2: CAD/CAM wax patterns. Group3: 3D Printing of resin patterns. All patterns were invested to construct E-max crowns. The ceramic crowns were seated on their corresponding prepared teeth and the vertical marginal gap was measured with a binocular microscope (90X). Then internal gap of each ceramic crown was measured using the silicone replica technique. Aftercementation, each ceramic crown was statically, compressively and axially loaded until fracture at a cross head speed of 1 mm/min using a steel rod placed centrally at the occlusal surface of the crowns to evaluate the fracture resistance of the crowns. Results: Group 1 showed the largest marginal gap mean (85.74±2.58μm) followed by group 2; (74.06±3.27μm) and then group3 (69.35± 3.44μm). These differences were statistically significant among the groups. The results of internal gap distances in group 1 (112±7.66μm) followed by group 2 (100±5.76μm) and then group3 (82± 7.2μm), the differences between the groups were statistically significant. The mean fracture resistance values of groups 1, 2 and 3 were 850.67±25.30N, 1080.01±47.06N and 1412.18±28.92N respectively. Post hoc test revealed that the differences between groups 1 and 2 as well as between groups 2 and 3 were statistically insignificant; however, the difference between groups 1 and 3 was statistically significant. Spearman’s rank correlation coefficient showed value of - 0.781. The negative sign indicates that the fracture resistance of the samples decreased as the internal gaps increased Conclusions: The 3D printed pattern resulted in an E-max crown with better marginal adaptation and internal fitness. The fracture resistance of E-max crown was improved as its internal adaptation was enhanced.

Mostafa Ahmad Abd El Atif Eldessouky

Reem Gamal, Yasser F Gomaa, Mostafa A Abdellatif

01/10/2015

Aim of the study: This in vitro study was conducted to evaluate nanoleakage of two contemporary dual cured self-adhesive resin cements bonding high strength ceramic to dentin. Materials and Methods: sixteen rectangular-shaped zirconia blocks (ICE Zirkon Translucent ZirkonZhan, Italy) were fabricated and divide into two group according to cements used for cementation of zirconia blocks to freshly prepared flat dentin surfaces to form assemblies. (Group1- RelyX™ U200 (RXU200), (3M ESPE Germany) and group2- Multilink® Speed (MS), (Ivoclar Vivadent, Liechtenstein)). Each group were divided to three subgroups ten assemblies in each according to storage periods 1day, 7 days without thermocycling and 7 days with thermocycling for 500 cycles at temperature between 5 and 55˚C. At the end of each follow up period the assemblies were sectioned into1 mm thick slaps. Two slaps from each assembly were selected, stained with 50wt% ammoniacal silver nitrate and tested for nanoleakage using Electron Dispersive Analytical X-ray (EDAX). Results: Group 2 showed the higher insignificant mean of nanoleakage (15.55±4.47 AgL in wt%) than group 1 (13.83±5.36 AgL in wt%). One day follow-up period showed the highest significant mean of nanoleakage (18.35±4.18 AgL in wt%) followed by seven days without thermocycling (13.10±4.44 AgL in wt%) and 7 days with thermocycling (11.87±4.13 AgL in wt%). Conclusions: RXU200 cement had lower mean of nanoleakage than MS and Storage time had influences on nanoleackage but thermocycling had not.

Mostafa Ahmad Abd El Atif Eldessouky

Rasha M. Abdelraouf, Dalia A. Saba, Mostafa A. Abdellatif

01/10/2015

Statement of the Problem: The presence of an esthetic restorative materials offering high strength is considered an ambition for all dental clinicians. Purpose: The aim of this study was to evaluate and compare the mechanical properties of two commercially available yttrium partially stabilized zirconia ceramics (translucent versus conventional) in terms of their biaxial flexural strength and indentation fracture toughness. Materials and Methods: Two commercially yttrium partially stabilized zirconia blocks were used; Incoris TZI (Sirona-Dental-systems-GmbH, Biberach, Germany) representing the translucent zirconia and VITA In-Ceram YZ (VITA, Zahnfabrik, Germany) as the conventional zirconia. Disc-shaped specimens were prepared (15 mm in diameter and 1.2 mm in thickness), (n=10/gp). Five specimens from each group were used for measuring the biaxial flexural strength using a universal testing machine. The indentation fracture toughness of both zirconia types were measured by Vickers hardness testing machine, (n=5/gp). Results were statistically analyzed using Student’s T-test. Results: The biaxial flexural strength and the indentation fracture toughness values of both the Incoris TZI and VITA In-Ceram YZ were (738.2±59.5, 737.9±142.7 MPa) and (4.2±0.2, 3.9±0.2 MPa×m1/2) respectively, with insignificant differences. Conclusion: Within the limitations of this study, it was concluded that translucent Zirconia provides a promising material combining both strength and esthetics.

Mostafa Ahmad Abd El Atif Eldessouky

Hanaa Farouk; Mouhammed Souhail; Yasser F Gomaa; Mostafa A Abdellatif

01/10/2013

Aim of the study: This study aimed to evaluate the interface between teeth and resin composite restoration bonded with a fluoride releasing self etching adhesive through dye penetration and SEM. Materials and Methods: Eighty intact caries free anterior teeth were selected and randomly divided into two groups. The first group received class V cavities in the gingival one third of facial and palatal surfaces. In the second group enamel was first removed then class V cavities were prepared directly in the dentin. Each group was divided into two subgroups according to the adhesive type. Two adhesive systems were used; a fluoride releasing adhesive (AdheSE-One F) and a non fluoride releasing one (AdheSE). The adhesives were applied to the prepared cavities and cured then resin composite restorations were applied and cured. Dye penetration test as well as SEM evaluation for gaps and percentage contact were performed to evaluate the adhesive junctions. Results: For dye penetration test, the fluoride releasing adhesive showed no significant higher penetration than with the non fluoride releasing one. The SEM evaluation revealed that the fluoride releasing adhesive resulted in significantly lower percentage contact and significantly higher gap values than with the non fluoride releasing one. Existence of enamel reduced the penetration of the dye and improved the percentage contact and minimized the gap values at the adhesive junction. Conclusions: Both adhesives showed Leakage but it was higher with the fluoride releasing one. KEY WORDS: Dye penetration; SEM; Adhesive.