Property Evaluation of Several Light Curable Veneer Cements

Dual-cure resin luting cement has problems of discoloration or color shifting. Light cure cement has shown better color stability and is more desirable as veneer cement.  Objectives: To evaluate several properties of an experimental light curable veneer cement, and compare this cement with several commercial light cure veneer cements.  Materials and Methods: Experiment light cure veneer cement clear (Exp. Clear, Pentron), RelyX™ Veneer cement Translucent (RelyX TR, 3M ESPE), Variolink^® Veneer High value +2 (Variolink HV+2, Ivoclar Vivadent), Choice™ 2 Veneer Cement Translucent (Choice 2 TR, Bisco) were tested. The veneer cements were light cured (1mm thick) and stored in distilled water for a week in 37 ^oC oven. The color readings, L, a, b were read before putting in water and after 1 week in water. The color change DE was calculated as: DE=[(L-L₀)²+(a-a₀)²+(b-b₀)²]^1/2, where L₀, a₀, b₀ were the readings before storage in water, and L, a, b were the readings after 1 week in water. Flexural strength (FS), water absorption (WA) and solubility (WS) were tested according to ISO 4049. Vicker's Hardness (VH) sample (3x10mm cylinder) was light cured 20s and tested 30 minutes after the sample preparation on Clark Instrument. Results: The properties of these veneer cements, DE, FS, VH, WA and WS are summarized in the table below.

Veneer Cement	DE	WA (mg/mm3/wk)	WS (mg/mm3/wk)	VH	FS (MPa)
Exp. Clear	0.86	8	1	43	127(11)
RelyX TR	2.69	25	12	40	112(12)
Choice 2 TR	1.51	15	4	44	138(7)
Variolink HV+2	10.35	18	3	25	116(13)

Conclusion: The Exp. Clear veneer cement showed a better color stability in water (DE<1).  It has lowest water absorption and water solubility.  The mechanical properties, as shown in Vicker's hardness and flexural strength, are comparative to the commercial products.