Evaluating the Influence of Ferrule Preparation on Zirconia Endocrown Efficacy in Primary Molars: A 3D Finite Element Analysis Ali Sayed Ali Bayiumy, Mohamed AboElkasme Wakwak, Salem Abdel Hakim Salem, Mohammed Said AbdAllah AbuSamadah, Mahmoud El-Said Ahmed Abd El-Aziz, et al. European Journal of Dentistry, 2026 This article assesses the effect of different ferrule preparations on the stress distribution in the primary second molar restored with zirconia crown.Four finite element models were created to simulate different ferrule heights: M1 (0 mm), M2 (1 mm), M3 (1.5 mm), and M4 (2 mm). A lower primary second molar was scanned to create a solid model, which was imported into finite element analysis software. Simulations included varying ferrule heights, material properties, and meshing. Models were subjected to 330 N occlusal loads at vertical, oblique, and lateral angles.The analysis revealed that stress within the endocrown body increased with greater ferrule height under vertical loading. Conversely, stress levels decreased with increased ferrule height under oblique and lateral loads. Under vertical load, peak stresses were recorded as follows: endocrown body (219.5 MPa for M1), cement layer (11.7 MPa for M1 and M4), remaining tooth (36 MPa for M1), cortical bone (59.7 MPa for M1), and cancellous bone (8.7 MPa for M1 and M4). Under oblique load, stress values increased as follows: cement layer (62.9 MPa for M4), remaining tooth (59 MPa for M1), and endocrown body (203 MPa for M1). Under lateral load, stress values increased as follows: endocrown body (321 MPa for M1), cement layer (100 MPa for M4), remaining tooth (94 MPa for M1), cortical bone (154 MPa for M1), and cancellous bone (15 MPa for M1).Ferrule height significantly influences stress distribution in the tooth structure and supporting bone. Higher ferrule heights enhance structural stability by reducing stress on underlying components.
Endocrown Feasibility for Primary Molars: A Finite Element Study Aeshah Hassan Abduljabar, Ahmad Waleed Iskander, Mohamed Taha Elfezary, Mohamed AboElkasem Ahmed Wakwak, Wafa Abdullah Bathabt, et al. European Journal of Dentistry, 2024 Objective To study the possibility of using pediatric endocrowns to restore the second primary molar using three-dimensional (3D) finite element analysis. Design A 3D finite element model was built for a pediatric mandibular molar, starting with laser scanning a naturally extracted tooth. The access cavity had an elliptic shape with 6 mm width, 4 mm height, and 2 mm depth with a wall taper angle of 5 degrees.Two materials (Zr and E-max) were tested for the endocrown and two cementing materials (glass ionomer and resin cement) with 20 to 40 μm thickness. Twelve case studies were reported within this research as the applied load of 330 N was tested with three angulations vertical, oblique at 45 degrees, and laterally. Results Twelve linear static stress analyses were performed. The resultant stresses and deformations' distribution patterns did not alter much, and values were within the threshold of physiological tolerance. Deformations were negligibly changed with changing endocrown and cement materials. In contrast, endocrown stresses indicated zirconia endocrown would have a long lifetime, while E-max one will have a relatively short lifetime. Conclusions Analysis results indicated that bone was negligibly affected by changing endocrowns and cementing materials. Both tested endocrown materials can be used safely. Zirconia endocrowns may have a much longer lifetime than E-max.
Effect of chitosan nanoparticles on microtensile bond strength of resin composite to dentin: An in vitro study Amr Mohsen Mohamed, Sameh Mahoud Nabih, Mohamed Ahmed Wakwak Brazilian Dental Science, 2020 Objective: The purpose of this study was to evaluate the effect of chitosan nanoparticles on microtensile bond strength of resin composite to dentin using self etch adhesive after aging. Material and Methods: A total number of 90 freshly extracted, sound human molar teeth. Flat tooth surface was gained after cut of the occlusal surface. Three main groups according to pretreatment of dentin before adhesive application; 0.2 % chitosan, 2.5 % chitosan and no treatment control group. Universal self etch adhesive were applied according to manufacture instruction and 4 mm of Feltik Z250 xt composite. Storage of specimens for 1 day, 3 months and 6 months in 37O C distilled water. After that, the tooth was sectioned to beams of 1 mm x8 mm sticks for microtensile bond strength test using universal testing machine. Scanning electron microscope (SEM) was used to evalute the effect of chitosan nanoparticles on dentin and smear layer. Kruskal-Wallis test was used to compare between the three groups as well as the three aging periods. Dunn’s test was used for pair-wise comparisons. The significance level was set at P ? 0.05. Results: chitosan 0.2% is statistically significant increase in bond strength than chitosan 2.5% and control in one day group. Three months chitosan 0.2 % groups have statistically significant increase in bond strength than chitosan 2.5%. It was found in 6 months that control and chitosan 0.2 % have statistically significant increase in bond strength than chitosan 2.5%. There was statistically significant difference found between the three studied groups regarding bond strength at different storage times . Conclusion: Microtensile bond strength was influenced by different chitosan concentration. Different aging periods had no effect on the microtensile bond strength without application of chitosan and with application of 2.5% chitosan concentration.KEYWORDSChitosan nanoparticles; Microtensile bond strength; MMPs.
Evaluation of microtensile bond strength of universal self-etch adhesive system to wet and dry dentin Mohamed Ahmed Wakwak, Eslam Hassan Gabr, Ahmed Mohamed Elmarakby Open Access Macedonian Journal of Medical Sciences, 2020 BACKGROUND: The durability of dentin-resin interfaces with the universal adhesive system is a crucial characteristic with chemical interactions between the exposed collagen and the adhesive monomers, but it is still compromised with wet and dry mode.
 AIM: The present study evaluated the effect of dentin wetness and solvents containing of one-step self-etch adhesives on the microtensile bond strength (μTBS) of dentin at different storage times.
 METHODS: Occlusal dentin of 54 extracted human molars was exposed. Each adhesive agent was applied according to manufacturer instructions to wet and dry dentin surfaces. Composite resin was incrementally built up. Bond strengths to dentin were determined using the μTBS test after water storage for 24 h, 1 month, and 6 months. One-way ANOVA was used to compare between more than two non-related samples. The significance level was set at p ≤ 0.05.
 RESULTS: Dryness of dentin increases the μTBS with solvent-containing adhesives while decrease the μTBS with solvent-free adhesive. There was an increase in microtensile bond strength values in the case of ethanol water-based self-etch adhesive over time. No statistically significant difference was found among different storage times regarding μTBS for solvent-free adhesive, while a statistically significant difference was found among different storage times in μTBS for solvent-containing adhesives.
 CONCLUSION: Universal adhesive systems improve the durability and stability of dentin bond strength.
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'In Vitro Study Compared The Shear Bond Strength of HEMA-free and HEMA-containing Bonding Agents To Different Dentin Surface Treatments', Al-Azhar Dental Journal for Girls, Wakwak Al-Azhar Dental Journal for Girls 4 (4) , 2017 2017 Citations: 4
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