Physical Properties of Bis-Acryl Provisional Resin Materials

Objective:  The flexural strength (FS) and flexural modulus (E_f) of three chemical-cure (Protemp Garant 3, PerfecTemp II, Temphase) bis-acryl, one dual-cure (Luxatemp Solar) bis-acryl and a polyethyl methacrylate (Trim) provisional resin material were evaluated.  Methods:  Beam-shaped specimens (25mm x 2mm x 2mm) (n=20) were prepared in a metal-backed teflon split mold maintained at 37șC ± 1șC for a period of five minutes in order to simulate clinical conditions.  An additional group (Trim P) was cured under pressure.  Specimens were then removed from the split mold, stored in 37șC distilled water and tested at 1 and 24 hours on an Instron testing machine utilizing a three-point loading jig at 1.0mm/min displacement rate.  Apparent E_f were calculated from the corrected load-deflection plots.  Results:  Mean values for FS (MPa) and E_f (GPa) with standard deviations are listed below:

FS			Ef
Resin	1h	24h	1h	24h
Luxatemp Solar	49.7 (4.6)	92.7 (10.8)	1.42 (0.1)	2.62 (0.3)
Integrity	40.1 (5.4)	92.3 (7.9)	1.01 (0.2)	2.94 (0.3)
Protemp 3	63.8 (6.9)	84.8 (7.3)	1.76 (0.1)	2.51 (0.2)
Temphase	40.7 (5.5)	79.2 (9.9)	1.27 (0.2)	2.45 (0.2)
PerfecTemp II	35.7 (3.7)	68.9 (6.6)	1.01 (0.1)	2.35 (0.3)
Trim	34.7 (2.2)	34.7 (2.1)	1.0 (0.1)	1.52 (0.1)
Trim P	33.1 (3.0)	31.1 (3.4)	1.01 (0.1)	1.41 (0.1)

ANOVA (p<0.001) and Ryan-Einot-Gabriel-Welsch Test (p<0.05) showed significant differences between provisional resins for both FS and E_f at 1 and 24 hours.  Conclusions:  The initial (1hr) strength properties (FS and E_f) of Protemp 3 were significantly greater than all other resins tested.  Post-gelation polymerization seems to play an important role in determining the strength properties of both chemical and dual-cure bis-acryl resins within the first 24 hours.