Bond Compatibility of NX3 Resin-Cement with 7th Generation Adhesives

Most self-cured resin cements employing BPO/amine redox initiator system are not compatible with the 7^th generation adhesives, resulting in compromised adhesion.  A new dual-cure resin cement NX3 (Kerr) employing a new color-stable amine-free redox initiator system was recently introduced.   Objective: To test the dentin shear bond strength (SBS) of several 7^th generation adhesives {Clearfil S3 Bond (Kuraray), G-Bond (GC America), iBond (Kulzer), OptiBond All-In-One (Kerr), and Xeno IV (Dentsply)} using the following three resin cements {NX3 (Kerr), Calibra (Dentsply), and Variolink (Vivadent)} in self-cure mode to determine if NX3 provides improved bond compatibility.  Method: Dentin SBS test was conducted using a bonding jig (Ultradent) with cylindrical mold (D=2.38mm).  Each adhesive was used without an activator for the purpose of truly assessing the degree of incompatibility.  Each adhesive was light-cured, and each cement was self-cured.  The bonded specimens  (n=6 for each cement) were stored in de-ionized water at 37ºC for 24 hours before being subjected to shear force on an Instron mechanical tester.  Results: ANOVA revealed that, for all five adhesives, the SBS obtained with NX3 cement was significantly (p<0.05) higher than those obtained with Calibra and Variolink cements.   Excellent dentin bond strength or bond compatibility was achieved between self-cured NX3 and all five adhesives.

SBS, MPa
		Cement (self-cured)
		NX3	Calibra	Variolink
Adhesive	Clearfil S3 Bond	27.1±1.6a*	7.9±6.4b	12.7±6.5b
	G-Bond	25.7±1.2a	18.5±3.3b	14.7±3.3c
	iBond	26.0±0.6a	16.0±4.7b	16.0±6.6b
	OptiBond All-In-One	32.6±5.5a	11.8±1.7b	12.3±1.4b
	Xeno IV	33.2±9.3a	11.0±3.3b	7.4±1.5b

*Means with different letters within the same row are statistically different at p < 0.05.

Conclusions:  For all five adhesives, NX3 exhibited the highest SBS or best bond compatibility among the three cements tested.  NX3 achieves its excellent bond compatibility with 7^th generation adhesives without the need for an activator for the adhesive, thereby simplifying the cementation procedure.