Oral and Dental Medicine

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Accuracy of surgical guides fabricated using two different 3D printers for prosthetically driven implant surgery : An in-Vitro Study /
Semary, Amr Mohamed Abd Elfattah,; Supervisor : Hesham Katamish, Tarek Salah-Eldin Morsi, Mostafa Hussein.
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Accuracy of two digital scanners (intraoral, extraoral) compared to conventional impression using implant with different angulations (zero, 15°,25°) : "In vitro study" /
Rafla, Kirollos Ashraf Sobhy,; Supervisor : Rana Cherif, Lomaya Ghanem. Includes Arabic Summary.
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Bioactive Cement versus Resin Cement Regarding the Perceived Shade of E-Max Restorations : (An In Vitro Study)
Nagy, Amira Gehad
Esthetics is becoming the main concern for patients and professionals. Demands for creating a natural appearing smile has increased as it reflects youth and acceptance. The goal of esthetic dentistry is to restore teeth to meet the natural form, biocompatibility and appearance. To create a dental restoration that gives a natural looking requires accurate replication of size, shape, surface texture, contouring, translucency and color of natural dentition. Shade is an essential parameter that attracts attention of patients, they judge and accept their dental restorations based on shade matching especially in the anterior esthetic zone. For dental restoration with acceptable shade, translucency and fluorescence it should match that of natural dentition to mimic the vitality. In the past decades, porcelain fused to metal fixed prosthesis was the material predominantly used to restore teeth. But, unfortunately the metal layering acts as a barrier for light transmission giving the restoration dark opaque appearance. The introduction of metal free restorations all-ceramic restorations, have proved to be an excellent alternative for porcelain fused to metal. These restorations utilize more conservative preparation because of the continuous improvements in their mechanical, physical properties and processing methods. Introduction Ceramic type, thickness, shade, firing temperature and bonding affects the final appearance of restoration. Lithium disilicate was launched in 1998 by Ivoclar Vivadent; it is one of the most famous glass- ceramics. It has adequate mechanical properties and offers attractive esthetic quality. One of the most important factors that affect the color of dental restorations is the cement used. Type, thickness, curing method and shade affects the perceived shade of the restoration and it’s stability over time. Resin cements are widely used for cementation of lithium disilicate as it bonds chemically to underlying glass- ceramic increasing strength and longevity of dental restoration. Furthermore, it has a clinically accepted color effect and stability. Newly introduced bioactive dental cement with ionic resin matrix is claimed to mimic the physical and chemical properties of natural teeth. In addition, it releases and recharge of calcium, phosphate and fluoride. It would be challenging to investigate the shade of lithium disilicate samples cemented with bioactive cement and comparing it with samples cemented with resin cement.
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Color masking effect of ultra-opaque resin cement with different ceramic systems : (An in-vitro study) /
AL-Masry, Lydia Mahmoud,; Supervisor : Tamer Elhamy Shokry, Talaat Samhan. Includes Arabic Summary.
Cement criteria considered as one of the important factors that influence shade on dental restorations. The perceived shade of restoration by the naked eye affected by cement type, thickness, shade and curing method. Aim of study was to test the effectiveness of the Ultra-Opaque luting cement (Vita Adiva IA-Cem) compared to the conventional one (Breeze) on masking the metal Ni-Cr substrate covered with three ceramic materials and evaluating its color stability after thermocycling. A total of 60 disc-shaped specimens were machined out of three types of monolithic CAD/CAM ceramic blocks: IPS e.max CAD, Vita Suprinity, and Katana ultra-translucent zirconia; 20 samples for each material. Shade A2 MT was chosen for the three materials. A total of 60 Ni-Cr metal disc shaped specimens were manufactured using a customized teflon mold with dimension 10mm X 1mmto and lost wax technique be adhesively cemented to ceramic one. CAD/CAM ceramic blocks were milled into cylinders with dimensions 10 mm diameter and 14 mm long (for e.max and vita suprinity) and 11 mm diameter and 14 mm long (For Katana zirconia). The cylinders were then sliced into discs with 1 mm thickness by using diamond sawing machine. The IPS e.max and Vita suprinity samples were crystalized and glazed in one step inside a firing furnace, Katana samples were also sintered and glazed in one step inside a sintering oven as well. For IPS e.max CAD and Vita Suprinity specimens, surface treatment was done using 9% hydrofluoric acid& rinsed for 1 minute under water spray and then silane coupling agent was applied for 1 minute. For Katana specimens, zirconia primer was used to apply one drop on the zirconia specimens before cementation as well. The metal disc specimens were then placed inside another custom made split teflon mold machined with the dimensions of 10mm X 2.1 mm and then the cement was applied on it using mixing tip to be cemented to the ceramic one under standard weight of 1 Kg. A portable Spectrophotometer was used to measure the baseline color of the specimens before cementation, after cementation of ceramic specimens to metal one and after being subjected to thermocycling process. Color masking and color changes results (DE) were obtained using equation DE = [(D L*)2 + (D a*)2 +(D b*)2] ½.
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Color stability of three different types of monolithic CAD/CAM esthetic restorations after exposure to artificial accelerated aging : (An In-Vitro Study).
Abdelhalim, Ahmed Magdy Mohamed,; Supervisor : Tamer Elhamy Shokry, Talaat Samhan.
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Comparing accuracy of surgical guides fabricated by additive method (3D printing) versus subtractive method (milling by CAD/CAM) for prosthetically driven implant placement : “An in-vitro atudy” /
Stino, Mounir Shafik Mounir,; Supervisor : Tarek Salah-Eldin Morsi, Talaat Samhan. Includes Arabic Summary.
Prosthetically driven implant surgery offers a higher degree of precision when placing dental implants, resulting in more predictable prosthetic outcomes compared to non guided surgeries. This study aimed to assess the precision of surgical guides produced through CAD/CAM milling and SLA 3D printing methods in achieving the desired implant positions for prosthetically driven implant placement. To conduct the study, twenty-four epoxy resin models, each featuring a missing mandibular first molar, were prepared. Implant placement was virtually planned using 3D implant planning software. Subsequently, twelve surgical guides were created by milling PMMA blocks, while another set of twelve guides was produced using a SLA 3D printer. The fit and stability of the surgical guides were meticulously assessed prior to the drilling procedure. A total of 24 dental implants (5.5×11 mm) were placed using tooth-supported surgical guides and a fully guided implant surgical kit. The placement of dental implants was digitally scanned utilizing scan bodies and an extra-oral scanner. Specialized 3D analysis software was employed to evaluate the implant positions and the accuracy of the surgical guides. This evaluation fabricated a comparison between the planned implant positions and the actual placements, with measurements of deviations recorded at the point of entry, apical position, and angular deviations. The root mean square (RMS) of errors was calculated for both sets of surgical guides. Statistical analysis was performed using the Mann-Whitney U test (P ≤0.05). Results of the study indicated that SLA 3D printed surgical guides exhibited higher accuracy when compared to CAD/CAM milled guides. Statistically significant differences were observed between the two in terms of angular deviation (P<0.001), while there was no significance difference in terms of point of entry (P=0.689), and apical position (P=0.471). Overall, SLA 3D printed surgical guides demonstrated lower deviations.
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Correlation between marginal fit and microleakage in gradient versus translucent monolithic zirconia crowns bonded with self- adhesive resin cement : In vitro study /
Faltas, Maro Ragai Wahbi,; Supervisor : Ashraf Mokhtar, Lomaya Ghanem. Includes Arabic Summary.
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Effect of blocking reverse taper preparation methods on the vertical marginal and internal fit of CAD/CAM monolithicZirconia crowns : (In-vitro study) /
Nageeb, Fady Remo Meshreky,; Supervisor : Ashraf Mokhtar, Hanaa Zaghloul. Includes Arabic Summary.
Undercuts are often considered a mistake in the preparation and conveyed to be a source of problem during impression taking and crown fabrication. Treatment methods to such problem include either sacrificing the tooth structure or blocking of the undercut. However, there is minimal scientific evidence regarding whether the digital algorithm will be able to substitute the conventional wax blocking in terms of producing tooth supported zirconia dental prosthesis with predictable vertical marginal accuracy and internal fit. So, The aim of this study was to evaluate the effect of blocking methods of reverse taper preparation (conventional wax blocking and digital software’s algorithm) on the accuracy of fit (vertical marginal and internal fit) of CAD/CAM monolithic zirconia crowns and to compare the accuracy of fit between zirconia crowns constructed over blocked preparation and 12o total occlusal convergence (TOC). Therefore, in the present study 3D printed dies mimicking a reduced upper molar were engineered with predetermined total occlusal convergence to assess the digital and conventional blocking methods. Thirty dies in total ten in control group with 12 o taper, ten with -4 o taper and ten with -8 o taper as shown in figure 1. Groups containing undercuts were further divided in equals and exposed to the two types of undercut blocking methods, digital and conventional. Groups IIA and IIIA were blocking conventionally using wax blocking and then scanned utilizing CEREC OMNICAM intra-oralscanner to provide a STL file for the zirconia fabrication. Groups IIB and IIIB were scanned first using CEREC OMNICAM intra-oral scanner and the designing software, EXOCAD, was used to digitally identify and block the undercut. Finally, the milled zirconia crowns were assessed in terms of the vertical marginal fit and internal fit. Vertical marginal fit was assessed by a stereooptical microscope on the 3D printed model. Five equidistant measurement points were taken from each surface (buccal, lingual, mesial and distal) with a total of 20 points and with the aid of an image analysis software vertical marginal values were acquired. Internal fit was assessed using silicone replica technique, after the sectioning of the specimen, measurements were taken as the mean of five equidistant 5 points of single proximal wall.
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Effect of ceramic thickness and substrate color on the final color of gradient zirconia based restorations : (An in-vitro study) /
Kamaleldin, Selwan Yehia,; Supervisor : Tamer Elhamy Shokry; Yara sayed. Includes Arabic Summary.
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Effect of changes in sintering parameters on color reproduction and translucency of multi-phase zirconia : (In-vitro study) /
Abdelrahman, Abdelrahman Amir Rashad,; Supervisor : Hesham Katamish, Tarek Salah, Yara Sayed Attia. Includes Arabic Summary.
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Effect of connector designs on flexural strength of gradient versus translucent monolithic zirconia fixed dental prosthesis : An in vitro study /
Abd-Elrahman, Yomna Gamal Lotfty ,; Supervisor : Ashraf Hassan Mokhtar, Tamer Abd El Rahim Hamza.
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Effect of cyclic loading on fracture resistance of 3Y-TZP and gradient 3Y-TZP/5Y-TZP veneered zirconia based fixed partial denture : (in-vitro study) /
Negm, Rana Mahmoud,; Supervisor : Tamer Elhamy Shokry, Lomaya Ghanem.
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Effect of digital blocking of reversed tapered preparations in comparison to conventional wax blocking on fracture resistance of monolithic zirconia crowns /
El-Hawary, Yara Mohamed Amin Emam,; Supervisor : Ashraf Hassan Mokhtar, Lomaya EL-Sayed Ghanem. Includes Arabic Summary.
The optimal taperness convergence of axial walls dictates retention, stability, resistance to fracture, and longevity. Reverse taper might affect fracture behavior of cemented restorations, they commonly occur 1n a lot of situations while preparing teeth which may be due to tilted tooth, difficult accessibility, and malocclusion. CAD/CAM technology has been developed to eliminate challenges in restoration production. In this study, preparing three different groups of 3D printed dies with TOC (12,-4,-8), all dies were made with 6mm height, 1.5 mm occlusal reduction, 1mm axial reduction and 0.8 mm chamfer finish line. Each group contains 10 samples of the same angle but different from other group. Blocking of reversed taper preparation was done by two techniques: conventionaly by wax which was done before scanning and digitally blocking. Scanning of the dies was done using intra-oral scanner (Omnicam), as for blocking dies digitally it was done by software algorithim and then designing of the restoration was done by Exocad software. Monolithic translucent zirconia crowns were milled for full coverage restoration with Roland DWX-51D Dental Milling Machine. Monolithic translucent zirconia is widely used for its high strength, translucency and excellent biocompatibility. It shows higher flexural strength with reduced occlusal thickness and does not detach from the core layer as in bilayered zirconia. Crowns were then polished, glazed and sandblasted by Al,O3 particles size 50 um. Self-adhesive resin cement (Thercem) was used for cementation as it contains 10 MDP for better bonding of zirconia using cementing device. Afterwards, fracture test was done using universal testing machine. For better interpretaion of the resutls fractographic analysis of the fractured parts was processed using SEM. After analysis it was found that only tapering angle had a significant effect on fracture resistance, while the effect of blocking technique and its interaction with tapering angle was not statistically significant.
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The effect of hydrothermal aging on the color stability of gradient zirconia : In vitro study /
Salah El-Din, Mennat Allah Khaled Mahmoud Salah,; Supervisor : Hanaa Hassan Zaghloul, Tamer Hamza. Includes Arabic Summary.
Color stability of ceramics is an important factor for the long- term success of esthetic restorations. So, the aim of the current study is the evaluation of the effect of hydrothermal aging on the color stability and the microstructure of gradient zirconia. For standardization of gradient zirconia discs, a resin disc with a 10 mm diameter and 1.5 mm thickness was constructed using 3D printing technology. Then the 3D resin disc was scanned by using an extraoral desktop scanner. Ten Gradient zirconia disc specimens were milled from IPS e.max ZirCAD Prime blank using 5-axis dental milling machine. Then the specimens were sintered, polished and glazed according to the manufacturer recommendations. Hydrothermal aging was carried out at 134oC temperature, 2 bar pressure for 5 hours in an autoclave to be equivalent to 3 to 4 years of aging in vivo. Color stability and microstructural changes of all disc specimens were tested two times; before and after accelerated hydrothermal aging. Color difference measurements (ΔE) were carried out using a spectrophotometer. The total difference in color, according to L*, a*, b* coordinates, is calculated with the following formula. ΔE= [(Δ L*)2 + (Δ a*)2 +(Δ b*)2 ] ½ ΔL*, Δa*, and Δb* represent the difference in the color parameters before and after hydrothermal aging. Where delta E (ΔΕ) of 3.33 or less was considered clinically acceptable . X-ray diffraction analysis was used to determine the crystalline phases inside the gradient Zirconia disc specimens before and after aging. The percentage of t-m phase transformation was calculated using Gravie Nicholson equation. Xm = Im (-1,1,1) + Im (1,1,1) / Im (-1,1,1) + Im (1,1,1) + It (1,0,1)
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Effect of impression techniques on screw loosening for screw retained implant supported restorations under cyclic loading : In-vitro study /
El-Sayed, Ahmed Amr,; Supervisor : Lamia Sayed Kheiralla, Mostafa Hussein. Includes Arabic Summary.
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The effect of nano-silica coating on micro-shear bond strength of CAD/CAM PEEK to resin cement : (An in-vitro study).
Tawfik, Nourhan Hussein,; Supervisor : Hanaa Zaghloul, Tamer Elhamy Shokry.
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Effect of two different surface treatment protocols and resin cement viscosities on shear bond strength of advanced lithium disilicate after thermocycling : (In vitro study) /
Thabet, Yomna Ezzuldin Mohamed,; Supervisor : Ashraf Hassan Mokhtar, Hanaa Hassan Zaghloul, Mostafa Hussien. Includes Arabic Summary.
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Evaluation of fracture strength and surface topography of interim prosthodontics fabricated using 3D printing compared to CAD/CAM Systems : (In-vitro study) /
Eid, Mohamed Khaled Mohamed,; Supervisor : Jihan Farouk Mohamed Younis, Tamer Hamza. Includes Arabic Summary.
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Evaluation of the efficacy of different surface treatments on the fracture resistance of endocrown fabricated using PEEK material : (an in vitro study).
ElKady, Bassant Hazem,; Supervisor : Ashraf Hassan Mokhtar, Jihan Farouk.
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Evaluation of the surface roughness and Biofilm adhesion of PEEK vs monolithic zirconium : "an in-vitro study".
Khalifa, Farah Tarek,; Supervisor : Ahmed Hassanien, Tamer Hamza.