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Development of strength in dental silver amalgam
1Dental Materials Science, Dept of Bioclinical Sciences, Faculty of Dentistry, Health Sciences Centre, Kuwait University, Jabriya, Kuwait. b.w.darvell@hku.hk
Summary
The ball-on-disc test effectively measures dental silver amalgam strength development. Early strength testing, starting at 2 hours, is recommended for compliance and patient safety.
Area of Science:
- Materials Science
- Biomaterials Engineering
- Dental Materials Science
Background:
- Dental silver amalgam requires strength assessment during its setting process.
- Early strength development is crucial for patient instructions and standards compliance.
- The Hertzian 'ball on disc' method offers a potential solution for strength characterization.
Purpose of the Study:
- To characterize the strength development of dental silver amalgam during setting.
- To evaluate the 'ball on disc' method for early strength measurements.
- To assess the method's suitability for standards compliance testing.
Main Methods:
- Sixteen dental silver amalgam products were tested using the 'ball on disc' protocol at various time points (1-24h).
- Specimens were tested in Hertzian mode on a universal testing machine, recording load at first crack and radial crack count.
- Testing involved a 20mm steel ball on the amalgam specimen placed on a glass-filled polyamide disc.
Main Results:
- All tested amalgams exhibited clinically relevant radial cracking.
- Significant variations in setting rates and strength development were observed among different products.
- The load at failure data followed a lognormal distribution, with an overall RMS coefficient of variation of 12.4%.
Conclusions:
- The 'ball on disc' test is a facile and relevant method for assessing dental silver amalgam strength.
- This method is viable for standards compliance testing of dental amalgams.
- Early strength testing, with a minimum of 2 hours post-setting, is recommended.
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