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Your search keyword '"Assadollah Ahmadzadeh"' showing total 4 results
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4 results on '"Assadollah Ahmadzadeh"'

1. Spectrophotometric comparison of two porcelain systems, VMK master and VM13 with the VITA 3D-master shade guide (An in vitro study)

Author

Assadollah Ahmadzadeh, Sara Mansourinejad, Sanaz Mansourinejad, and Ali Rohani

Subjects
dental porcelain, shade matching, spectrophotometer, vmk master porcelain, vita vm13 porcelain, Dentistry, RK1-715
Abstract

Background: Accurate shade matching of metal-ceramic restorations with natural teeth is one of the most challenging aspects of dental restorations and esthetic dentistry. The aim of this study was to evaluate of the color parameters of two types of porcelain systems VMK Master and VM13 porcelain with VITA 3D-master shade guide. Materials and Methods: In this in vitro study a total of 56 metal discs (10 mm diameter and 2 mm thickness) were fabricated. Each of the disks was veneered with porcelain (Vita Zahnfabrik, Bad Sackingen, Germany) of the VITA shade. The discs were randomly divided into four groups (2M2 and 3M2 from VM13, 2M2 and 3M2 from VMK master) of 14 (n = 14). The spectrophotometer was used for taking color measurements based on the numerical color data of the CIELAB color system. Data analysis was performed by t-test (P < 0.05). Results: Comparison of color parameters in different porcelain showed that the type of porcelain caused a significant difference in color parameters (L, a, and b) (P < 0.05). The degree of translucency (L*) or glaze of VMK porcelains was higher than VM13, but the parameters a* and b* were higher in VM13 porcelains than VMK (P < 0.05). Furthermore, the color difference of two porcelain in 2M2 (1.63 ± 0.84) and 3M2 (1.71 ± 0.96) shades was within the acceptable clinical limit. Considering the total color difference (ΔE), there were no significant differences between the ΔE values produced by any of shades (P > 0.05). Conclusion: In the present study, the spectrophotometric analysis revealed that the porcelain shade type causes a change in the color parameters, but the color difference between two porcelains VMK and VM13 is within the acceptable range of clinical color. Therefore, both porcelain systems with 2M2 and 3M2 shades are suitable for enhancing the results of restorative dentistry.

Published
2022
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3. Spectrophotometric comparison of two porcelain systems, VMK master and VM13 with the VITA 3D-master shade guide (An

Author

Assadollah, Ahmadzadeh, Sara, Mansourinejad, Sanaz, Mansourinejad, and Ali, Rohani

Abstract

Accurate shade matching of metal-ceramic restorations with natural teeth is one of the most challenging aspects of dental restorations and esthetic dentistry. The aim of this study was to evaluate of the color parameters of two types of porcelain systems VMK Master and VM13 porcelain with VITA 3D-master shade guide.In thisComparison of color parameters in different porcelain showed that the type of porcelain caused a significant difference in color parameters (L, a, and b) (In the present study, the spectrophotometric analysis revealed that the porcelain shade type causes a change in the color parameters, but the color difference between two porcelains VMK and VM13 is within the acceptable range of clinical color. Therefore, both porcelain systems with 2M2 and 3M2 shades are suitable for enhancing the results of restorative dentistry.

Published
2017

4. Finite Element Study of Three Different Treatment Designs of a Mandibular Three Implant-Retained Overdenture

Author

Mohammad Shishesaz, Amin Baharan, and Assadollah Ahmadzadeh

Subjects
Materials science, genetic structures, Overdenture stability, implant, cortical bone, Aerospace Engineering, Ocean Engineering, Mandibular first molar, 03 medical and health sciences, 0302 clinical medicine, Premolar, medicine, General Materials Science, lcsh:QC120-168.85, Civil and Structural Engineering, Orthodontics, Mechanical Engineering, Linear elasticity, 030206 dentistry, Finite element method, medicine.anatomical_structure, cancellous bone, Mechanics of Materials, Automotive Engineering, Ball (bearing), lcsh:Descriptive and experimental mechanics, Cortical bone, Implant, lcsh:Mechanics of engineering. Applied mechanics, lcsh:TA349-359, Cancellous bone, human activities, 030217 neurology & neurosurgery, Biomedical engineering
Abstract

This study compares ball, bar-clip and bar-ball attachment systems for implant-retained mandibular overdentures with three implants. The first implant is placed in the middle of the mandible and the other two are imbedded in the first premolar regions. Linear elastic finite element analysis is used for design analysis. Three dimensional geometry of the mandible is generated from computed tomography. Other parts are modeled using SolidWorks software. The foodstuff is positioned at the right first molar, representing the most frequent masticating situation. To obtain accurate mesh-independent results, finite element models are solved using several mesh grids. They are then validated by means of a detailed convergence analysis. The results demonstrate that the highest von-Mises stress in the bone is always located around the neck of the implant, at its upper threads. Ball and bar-ball attachments transfer the highest and lowest stresses to the bone surrounding the implants, respectively. The lowest stresses in the cortical and cancellous bones are due to bar-ball attachment. Yet, the overdenture gets its maximum movement for this arrangement. Consequently, the use of bar-ball attachment is only recommended for the cases in which stress transferred to peri-implant bone is more important than overdenture stability. Among the three treatment designs, ball attachment seems to exhibit the lowest lateral and overall displacements and hence, better overdenture stability.

Published
2016

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