Flexural and fatigue strengths of denture base resin.
BACKGROUND
Mechanical properties of denture acrylic resins are important for the clinical success of multiple types of prostheses. Acrylic resins must be strong and resilient so as to withstand impact. Few studies utilize cyclic loads to characterize material response to repeated stress.


OBJECTIVE
The purpose of this study was to evaluate static and dynamic flexure properties of a variety of acrylic resins utilized in the fabrication of prostheses: (1) heat-polymerized polymethyl methacrylate (PMMA), powder-liquid type, and (2) a newly introduced, visible light-polymerized urethane dimethacrylate dough type.


METHODS
Twenty rectangular bars each of 4 PMMA acrylic resin materials (Diamond D, Fricke HI-I, Lucitone 199, Nature-Cryl Hi-Plus) and 1 urethane dimethacrylate (Eclipse) were fabricated and stored in 100% humidity for 30 days. Half of the specimens for each group were submitted to a static 3-point flexure test. The other half was submitted to cycling loading at 5 Hz for 10(4) cycles. Data were analyzed using 1-way ANOVA and 2-way ANOVA, followed by Tukey HSD or Bonferroni post hoc tests when necessary (alpha=.05).


RESULTS
Mean static flexure strength (SDs) in MPa were: Eclipse, 127.11 (5.83); Diamond D, 84.92 (5.10); Lucitone 199, 83.96 (11.96); HI-I, 79.54 (5.84); and Nature-Cryl Hi-Plus, 75.82 (6.96). Mean flexural strengths (SDs) in MPa postcycling were: Eclipse, 113.36 (31.29); Diamond D, 88.26 (5.46); Nature-Cryl Hi-Plus, 81.86 (4.93); HI-I, 79.18 (6.60); and Lucitone 199, 74.34 (4.95).


CONCLUSIONS
The visible light-polymerized urethane dimethacrylate resin (Eclipse) showed greater flexure strength than all PMMA heat-polymerized resins for both static and cycled groups (P<.001). Yet the Eclipse material had lower load limits, and demonstrated brittle-type behavior and greater standard deviations. The heat-polymerized PMMA materials did not significantly differ from each other after static or cyclic testing.
Diaz-Arnold
Ana M
AM
Department of Family Dentistry, University of Iowa, College of Dentistry, Iowa City, Iowa 52242, USA. ana-arnold@uiowa.edu
Vargas
Marcos A
MA
Shaull
Kenneth L
KL
Laffoon
John E
JE
Qian
Fang
F
D000180:Acrylic Resins; D000704:Analysis of Variance; D003188:Composite Resins; D003799:Dental Stress Analysis; D003819:Denture Bases; D008422:Materials Testing; D008689:Methacrylates; D018583:Pliability; D019904:Polymethyl Methacrylate
D000180:Acrylic Resins; D003188:Composite Resins; C509237:Eclipse Prosthodontic Resin; D008689:Methacrylates; D019904:Polymethyl Methacrylate