title: High-impact strength acrylic denture base material processed by autoclave.
abstract: OBJECTIVE
  To investigate the effect of two different cycles of autoclave processing on the transverse strength, impact strength, surface hardness and the porosity of high-impact strength acrylic denture base material.
  
  
  METHODS
  High Impact Acryl was the heat-cured acrylic denture base material included in the study. A total of 120 specimens were prepared, the specimens were grouped into: control groups in which high-impact strength acrylic resins processed by conventional water-bath processing technique (74°C for 1.5 h then boil for 30 min) and experimental groups in which high-impact strength acrylic resins processed by autoclave at 121°C, 210 kPa .The experimental groups were divided into (fast) groups for 15 min, and (slow) groups for 30 min. To study the effect of the autoclave processing (Tuttnauer 2540EA), four tests were conducted transverse strength (Instron universal testing machine), impact strength (Charpy tester), surface hardness (shore D), and porosity test. The results were analyzed to ANOVA and LSD test.
  
  
  RESULTS
  In ANOVA test, there were highly significant differences between the results of the processing techniques in transverse, impact, hardness, and porosity test. The LSD test showed a significant difference between control and fast groups in transverse and hardness tests and a non-significant difference in impact test and a highly significant difference in porosity test; while, there were a highly significant differences between control and slow groups in all examined tests; finally, there were a non-significant difference between fast and slow groups in transverse and porosity tests and a highly significant difference in impact and hardness tests.
  
  
  CONCLUSIONS
  In the autoclave processing technique, the slow (long) curing cycle improved the tested physical and mechanical properties as compared with the fast (short) curing cycle. The autoclave processing technique improved the tested physical and mechanical properties of High Impact Acryl.
authors.affiliation: Department of Prosthodontics, The Specialized Dental Health Center, Ministry of Health, Iraq. Electronic address: salwan.sami@yahoo.com.
authors.forename: Salwan Sami
authors.initials: SS
authors.lastname: Abdulwahhab
mesh_terms: D000180:Acrylic Resins; D019245:Compressive Strength; D003764:Dental Materials; D003799:Dental Stress Analysis; D003819:Denture Bases; D006244:Hardness; D006245:Hardness Tests; D006358:Hot Temperature; D008422:Materials Testing; D058105:Polymerization; D016062:Porosity; D013314:Stress, Mechanical
chemical_list: D000180:Acrylic Resins; D003764:Dental Materials
keywords: Autoclave; Hardness; High-impact strength acrylic; Porosity; Transverse