Publications by authors named "Syed Hammad Hassan"

5 Publications

  • Page 1 of 1

Analysis of enamel and material wear by digital microscope: an in-vitro study.

Braz Oral Res 2020 10;33:e121. Epub 2020 Jan 10.

Margalla Institute of Health Siciences - MIHS, Margalla College of Dentistry, Head of Prosthodontics Department, Rawalpindi, Pakistan.

The objective of the study was to analyze the surface area (SA) of the wear caused by simulated chewing on human enamel and opposing restorative material, namely: composite resin (CR), porcelain fused to metal (PFM), lithium disilicate (LD), or monolithic zirconia (MZr). Forty-eight premolars were selected as enamel specimens and divided randomly into 4 groups (n = 48; n =12) used as antagonists in chewing simulation (250,000 loading cycles) against one of the four selected test materials. Enamel and material specimens were scanned and evaluated under digital microscope, and wear SA (mm2) were recorded. Descriptive statistics, paired t-test, one-way ANOVA, and post-hoc Tukey-HSD tests were used for statistics (p < 0.05). The smallest and largest SA were exhibited by enamel against LD (0.80 mm2) and PFM (1.74 mm2), respectively. PFM (3.48 mm2) showed the largest SA and CR (2.28 mm2) showed the smallest SA. Paired t-test for SA values showed significant difference (p < 0.05) in all wear comparisons between materials and enamel antagonists. The wear of materials were greater than that of their respective enamel antagonists (p < 0.05). One-way ANOVA of the logarithmic means of wear SA revealed significant differences (P<0.05). Post-hoc Tukey test revealed significance for PFM (p < 0.05) with other materials. Wear of all test materials was greater compared to the wear of enamel antagonists. PFM and LD caused the largest and the smallest enamel wear, respectively. CR, LD, and MZr are more resistant than PFM to wear after simulated chewing against enamel.
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http://dx.doi.org/10.1590/1807-3107bor-2019.vol33.0121DOI Listing
January 2020

Effect of platform switching on peri-implant bone: A 3D finite element analysis.

J Prosthet Dent 2019 Jun 31;121(6):935-940. Epub 2019 Jan 31.

Resident, Postgraduate Prosthodontics, Department of Prosthodontics, Armed Forces Institute of Dentistry, Rawalpindi, Pakistan.

Statement Of Problem: A consensus regarding the effects of platform switching on peri-implant marginal bone levels is lacking. Finite element studies have reported contradictory results.

Purpose: The purpose of this finite element analysis study was to evaluate stress distribution in platform-switched (PS) and platform-matched (PM) implants and their surrounding bone.

Material And Methods: An implant (4.5×11 mm) was modeled and screwed into a human mandibular bone block using a computer-aided design (CAD) software program. Two separate models were generated: (1) PM, 4.5-mm implant with 4.5-mm-wide abutment and (2) PS, 4.5-mm implant with 3.5-mm-wide abutment. Implant components were modeled with linear isotropic properties and bones with anisotropic properties. Vertical (200 to 800 N) and oblique (50 to 150 N) forces were applied to each model to simulate occlusal loads. Linear elastic analysis was performed using ANSYS Workbench 16. von Mises equivalent stresses in the implant assemblies and peri-implant bone were calculated and compared with independent samples t test (α=.05).

Results: von Mises equivalent stress values under simulated axial and nonaxial occlusal loads were lower for PM than for PS implant assemblies. However, the differences were not statistically significant. Stress within the peri-implant bone was significantly higher for the PM group than for the PS group (P<.001).

Conclusions: Platform switching decreased stress within peri-implant bone and may help limit marginal bone resorption.
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http://dx.doi.org/10.1016/j.prosdent.2018.08.011DOI Listing
June 2019

Comparative abrasive wear resistance and surface analysis of dental resin-based materials.

Eur J Dent 2018 Jan-Mar;12(1):57-66

Department of Restorative Dental Sciences, College of Dentistry, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia.

Objective: The objective of this study was to assess the surface properties (microhardness and wear resistance) of various composites and compomer materials. In addition, the methodologies used for assessing wear resistance were compared.

Materials And Methods: This study was conducted using restorative material (Filtek Z250, Filtek Z350, QuiXfil, SureFil SDR, and Dyract XP) to assess wear resistance. A custom-made toothbrush simulator was employed for wear testing. Before and after wear resistance, structural, surface, and physical properties were assessed using various techniques.

Results: Structural changes and mass loss were observed after treatment, whereas no significant difference in terms of microhardness was observed. The correlation between atomic force microscopy (AFM) and profilometer and between wear resistance and filler volume was highly significant. The correlation between wear resistance and microhardness were insignificant.

Conclusions: The AFM presented higher precision compared to optical profilometers at a nanoscale level, but both methods can be used in tandem for a more detailed and precise roughness analysis.
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http://dx.doi.org/10.4103/ejd.ejd_380_17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5883477PMC
April 2018

Ceramic Fracture in Metal-Ceramic Restorations: The Aetiology.

Dent Update 2017 May;44(5):448-50, 453-4, 456

All dental restorations are liable to failure during function. Failure could be biologic, aesthetic, mechanical or a combination. Ceramic restorations in particular, including metal-ceramics, are prone to mechanical fracture, especially the fracture of veneering porcelain. Fracture of a metal-ceramic restoration jeopardizes function as well as aesthetics. It is equally onerous to manage for both patient and dentist. Optimal management of such cases requires a detailed knowledge of the aetiology behind this phenomenon. The current paper aims to highlight possible causative factors involved in the mechanical failures of metal-ceramic restorations. Clinical relevance: Ceramic fracture in metal-ceramic crowns and fixed partial dentures is routinely encountered in dental clinics. Knowledge of the aetiology is required to diagnose and manage such cases accurately as well as to avoid these errors in future.
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http://dx.doi.org/10.12968/denu.2017.44.5.448DOI Listing
May 2017

pH of Bottled Drinking Water in Islamabad.

J Coll Physicians Surg Pak 2017 Sep;27(9):587

Department of Prosthodontics, Army Medical College / Armed Forces Institute of Dentistry, National University of Medical Sciences (NUMS), Islamabad.

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http://dx.doi.org/2709DOI Listing
September 2017