Stiffness Measurement of Universal Composites

Objective: The purpose of this study is to compare the stiffness of different universal composites.

Method: The universal composites used in the experiments are: EsthetX HD A2 (lot#1106201, Dentsply); TPH 3 A3.5 (lot# 1102131, Dentsply) ; Filtek Z100 A2 (lot# 8GN, 3M); Filtek Z250 A2 (lot# N269383, 3M);  Filtek Xtra A2 (lot# N276480, 3M); Venus Diamond BL (lot# 010022, Heareus); Herculite Ultra A2E (lot# 3707940, Kerr) and Tetric EvaCeram A2 (lot#P02083, Ivaclar). AElite LS Packabe A2 (lot# 1100004101, Bisco). The stiffness of composites was measured by TA XT Plus Texture Analyzer.  A 1.7 gram of composite was dispensed into a hole (φ16mm x 4 mm) drilled in a stainless steel plate which was kept in an environmental chamber with constant temperature of 23^o C .  The excess amount of composite was removed by a Teflon spatula to make the paste surface even.  The cylinder probe (φ 4 mm ) aligned with the center of the hole started to approach the paste at 5.0 mm/s (pre-test Speed) until a 20.0 grams trigger force was detected.  The probe then began to compress the paste with a speed of 0.5 mm/s and traveled down a distance of 3 mm.  The curve of force vs time was recorded.    The slope (gradient) of the curve between 3.5 and 4 seconds was used as an indication of stiffness.  Means comparisons for all pairs using one way ANOVA Tukey’s test were applied for data analysis at a confidence level of 95%.

Result:

 

Glass Ionomers	Stiffness
	Mean (Kg/sec x 0.01)	Stdev (Kg/sec x 0.01)	Group
Esthet-X HD	12.7	0.9	A
Venus Diamond	11.8	1.0	A
Filtek Z250	9.9	0.5	B
Tetric EvaCeram	8.9	0.3	B, C
Herculite Ultra	7.5	0.4	C, D
AElite LS	6.9	0.3	D
TPH3	4.6	0.4	E
Filtek Supre Xtra	3.8	0.6	E
Filtek Z100	1.7	0.3	F

Conclusion: A wide range of stiffness was found among the nine tested universal composites.  Esthet-X HD Venus Diamond and Filtek Z250 exhibited the highest stiffness, while TPH3, Filtek Supre Xtra and Filtek Z100 exhibited the lowest stiffness.  Differences in stiffness has a direct influence over the clinician’s preference for composite handling properties during placement.