Author/Authors :
فرماني، سميه نويسنده Student Research Committee, Shiraz Dental School, Shiraz University of Medical Sciences, Shiraz, Iran Farmani, Somayeh , اورندي، سپيده نويسنده - , , سوخكيان، مهشيد نويسنده Student Research Committee, Shiraz Dental School, Shiraz University of Medical Sciences, Shiraz, Iran Sookhakiyan , Mahshid , مسه، آي سه نويسنده Department of Prosthodontics, School of Dentistry, Dicle University, Diyarbakir, Turkey Mese , Ayse
Abstract :
Statement of Problem: Hertzian indentation test has been proven to be an
efficient and reliable alternative upon Vickers hardness test. This method
has been used to test dental ceramics, amalgams, glass ionomers and luting
cements.There is limited published information about the load-bearing
capacity of resin composites using Hertizian indentation test.
Objectives: To investigate the load-bearing capacity of hybrid and
nano-hybrid resin composites stored dry or wet up to 30 days, using Hertzian
indentation test.
Materials and Methods: Three resin composites were used: two nano-hybrids
(Filtek Supreme, and Luna) and one hybrid, (Rok). A total of 108 disc-shaped
specimens (1mm thick x 10 mm diameter) were prepared using polyethylene mould.
The specimens of each material were randomly divided into 6 groups of 6
(n=6) and stored at 370C either in distilled water or dry for 1, 7 and 30 days.
The specimens were tested using Hertzian jig aligned in the universal
testing machine. The specimen was placed on the top of a disc-shaped
substrate. The load was applied at the center of each specimen and the load
at the first crack was recorded. Data were analyzed by ANOVA, Tukey’sand
student’s t-test using SPSS version 18.0.
Results: Three-way ANOVA showed a significant interaction between all
the factors (p = .0001). The load bearing capacity of almost all materials
reduced significantly in the wet condition in comparison with the dry
condition (p = .0001). After seven days of immersion in distilled water,
Filtek Supreme had significantly lower values than those of Rok and Luna,
there was no significant differences between materials in the dry condition.
Conclusions:In contrast to dry condition, the load-bearing capacity of
specimens stored in distilled water decreased significantly over the 30 days
of immersion. The load bearing capacity of nano-hybrid composites tested
in this study was shown to be comparable with that of the hybrid composite.
