@article{Rashid_2018, title={Temperature Effect on the Hardness of Different types of Resin Denture Base Materials}, volume={10}, url={https://mdj.uomustansiriyah.edu.iq/index.php/mdj/article/view/186}, DOI={10.32828/mdj.v10i1.186}, abstractNote={<p>The cold cured acrylic resin is inferior to heat cured acrylic resin from stand point<br>of strength and degree of polymerization. Many attempts have been made to improve<br>these properties. Because heat affects maturity of the chemical reaction of acrylic<br>resin therefore its maintenance during polymerization will affect the properties of<br>cured resin.<br>The purpose of this study was to evaluate the effect of increase curing temperature<br>on the hardness of two commercially available cold cured acrylic resin material<br>(Holland and Germany type) in comparison to heat cure resin and to those(cold cure)<br>curing by conventional methods in air at 23°C ± 5°C.<br>Ninety specimens,10 specimens from heat cure resin curing by water bath(short<br>cycle) and eighty specimens from cold cured acrylic [forty from cold cured<br>acrylic(Holland Type) and forty from cold cured acrylic(Germany type)] were<br>prepared , flasking and packing procedure were done according to manufacturer<br>direction and divided according to processing as follow:20 specimens(10 from<br>Holland type and 10 from Germany type) were processed in air for two hours at 23°C<br>± 5°C under press (bench curing) as a control, and 60 specimens(30 from Holland<br>type and 30 from Germany type) were processed by ivomat curing device containing<br>water under air pressure 30 Pascal for 15 minutes at different temperature: 40°C,<br>60°C, and 80°C(10 specimens for each groups) .All specimens were tested for<br>hardness test by shore D device (adigital model) for measuring the indentation<br>hardness of the specimens the test load was set to 50 Newton for shore (( D ))which is<br>suitable for acrylic resin material .<br>Result showed that heat cure resin show the maximum value of hardness<br>(88.8),followed by cold cured acrylic type Germany( polymerized by elevated<br>temperature 80˚C) (88.696) followed by cold cured acrylic type Holland polymerized<br>at 60˚C(88.471). While control group type Germany (polymerized at air bench)<br>recorded the minimum value of hardness (81.83). All groups that polymerized at high<br>temperature: 40°C, 60°C, and 80°C show the higher value of hardness in comparison<br>to those processed by conventional methods (at air bench at 23°C ± 5°C) with<br>significant and highly significant differences. There were highly significant<br>differences between heat cure acrylic and cold cure (both types) processed by<br>conventional methods and with cold cure Holland type processed at 40˚C, but there<br>were no significant differences between heat cure acrylic and cold cure (both types)<br>processed at high temperatures.<br><br></p>}, number={1}, journal={Mustansiria Dental Journal}, author={Rashid, Dr. Amal Abdul-Latif}, year={2018}, month={Feb.}, pages={69–76} }