Tensile Properties of Impression Materials

Objectives: The study determined tensile toughness, tensile strength, percent elongation and elastic memory of six addition silicone impression materials [Imprint 3 Ultra-Regular Body (I3URB), Imprint 3 Regular Body (I3RB), Examix NDS Regular Type (ENDS), Aquasil Ultra LV (AULV), Genie Light Body (GL), Standout Fast Set Wash (SOFW)]. Methods: Flat dumbbell specimens (2.0- and 0.5-mm thick) were set in water (35C) for the recommended intraoral setting time and were tested in tension on an Instron at a crosshead speed of 200mm/min. Elastic memory (deformation at 2 hours) was measured using gage bumps spaced 25mm apart with traveling microscope (15X) at initial elongations (50, 100, 150%). Means and standard deviations were analyzed by ANOVA and Fisher's PLSD test (p<0.05). Results:Values of properties at 2.0-mm are listed.

				Elastic	Elastic	Elastic
	Toughness,	Tensile	Percent	Memory	Memory	Memory
Product	N mm/mm3	Strength,MPa	Elongation	50% Elong.	100% Elong.	150% Elong.
I3URB	5.7(0.5)*	4.63(0.17)a	263(11)b	-0.05	-0.05	0.02
I3RB	5.2(0.4)a	4.54(0.19)a	252(7)b	-0.12	0.02	0.03
ENDS	4.9(0.9)a	2.81(0.18)	326(30)a	0.14	0.31	0.56
AULV	4.4(0.4)b	4.94(0.17)	185(10)	-0.01	1.18	2.09
GL	4.6(0.8)b	3.10(0.20)	255(28)b	-0.18	0.01	0.37
SOFW	3.4(0.5)	1.97(0.13)	326(30)a	0.19	0.67	1.20

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*Means with standard deviations in parentheses. For each property, means with the same superscripted letters are not different statistically (p=0.05).

Conclusions: I3URB and I3RB had highest toughness. AULV, I3URB and I3RB had highest tensile strength. ENDS and SOFW had highest percent elongation. Toughness, tensile strength and percent elongation of 2-mm thick specimens were up to 20% higher than 0.5-mm specimens. All materials exhibited acceptable elastic memory; however, I3URB, I3RB, ENDS, and GL were significantly less deformed. Supported in part by 3M ESPE.