Browsing by Author "El-Zawahry, Mohamed M"

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3D Finite Element Study on Incomplete Osseointegration: Locator Attachment versus Ball Attachment
(Open Access Macedonian Journal of Medical Sciences, 2021-02) ElGabry, Hisham S; Yousief, Salah A; Moubarak, Amal H; Eltaftazani, Iman A; El-Anwar, Mohamad; El-Zawahry, Mohamed M
BACKGROUND: Incomplete implant osseointegration may affect the choice of the type of attachment to ensure less amount of bone resorption, periods of maintenance, and longer implant/attachment life-time. AIM: The aim of this study was to evaluate, using 3D FE analysis (FEA), the influence of two different types of attachments on the rate of bone resorption, need for maintenance and implant/attachment life time in cases of unpredictable osseointegration in various bone types and using different implant angulations. METHODS: Six finite element models were prepared; three for the locator attachment while the other three for the ball attachment. Each of the three models simulates vertical implant and inclined implants by 10° and 20° degrees. Frictional contact between implant and cortical bone simulated the incomplete osseointegration scenario. RESULTS: Non-linear static analysis results showed that locator attachment and its cap may have longer time life in comparison with the ball attachment and its cap. CONCLUSIONS: Both attachments were safe for cortical and spongy bone, while the cortical bone receives less Von Mises stress by up to 33% with the increased implant angulation.
Influence of a V-shaped palatal vault on denture base materials’ characteristics: a finite element analysis
(Wolters Kluwer, 12/01/2016) Moussa, Amani R; El-Gabry, Hisham S; El-Zawahry, Mohamed M; El-Anwar, Mohamed I
Objectives In this study, the influence of a V-shaped palatal vault on the characteristics of denture base materials was studied. Materials and methods A finite element model was especially developed for this study with an average denture base thicknesses of 2 mm. Three different denture base materials were investigated under 100 N vertical and oblique loading. A linear static analysis was carried out. Results Finite element analysis showed a very low level of bone Von Mises stress under vertical loading, which means that three denture base materials and mucosa distributed the applied load and absorbed its energy perfectly, whereas mucosa was negligibly affected by changing denture base material and showed low/safe levels of stresses. Conclusion The V-shaped palatal vault affects denture base materials that, with a reduction in rigidity, will increase the mucosa-induced stress levels. Thus, denture base material selection requires a compromise between flexibility and durability
New dental implant selection criterion based on implant design
(Dental Investigations Society, 2017-04) El-Anwar, Mohamed I; Ibraheem, Eman M; El-Zawahry, Mohamed M; Zakaria Nassani, Mohammad; ElGabry, Hisham
Objective: A comparative study between threaded and plain dental implant designs was performed to find out a new criterion for dental implant selection. Materials and Methods: Several dental implant designs with a systematic increase in diameter and length were positioned in a cylindrical-shaped bone section and analyzed using finite element method. Four loading types were tested on different dental implant designs; tension of 50 N, compression of 100 N, bending of 20 N, and torque of 2 Nm, to derive design curves. Results: Better stress distribution on both spongy and cortical bone was noted with an increase in dental implant diameter and length. With the increase in dental implant side area, a stress reduction in the surrounding bones was observed, where threaded dental implants showed better behavior over the plain ones. Conclusions: Increasing value of ratio between dental implant side area and its cross-sectional area reduces stresses transferred to cortical and spongy bones. The use of implants with higher ratio of side area to cross-section area, especially with weak jaw bone, is recommended.