Dentin Bond Strength of NX3 Resin Cement

A new dual-cure resin cement NX3 (Kerr) employing a new color-stable, amine-free redox initiator system was recently introduced.  NX3 can be used with both total-etch and self-etch adhesives without the need for an activator as a result of its unique redox initiator system.   Objective: to test and compare the dentin shear bond strength (SBS) of NX3 in combination with either a total-etch adhesive OptiBond Solo Plus (Kerr) or a self-etch adhesive OptiBond All-In-One (Kerr) without an activator, along with several commercial resin cements in combination with their respective primers/adhesives/activator: Nexus 2 (Kerr), RelyX ARC (3M ESPE), Calibra (Dentsply), Variolink II (Ivoclar), Multilink (Ivoclar), and Panavia F2.0 (Kuraray). Methods: Dentin SBS test was conducted using a bonding jig (Ultradent) with cylindrical mold (D=2.38mm).  Each adhesive was applied according to its instructions for use, and each cement was self-cured.  The bonded specimens (n=6) were stored in de-ionized water at 37°C for 24 hours before being subjected to shear force on an Instron mechanical tester.  Results: ANOVA analysis revealed that, NX3 in combination with either a total-etch adhesive (OptiBond Solo Plus) or a self-etch adhesive (OptiBond All-In-One), produced significantly (p<0.05) higher dentin bond strength than other cement systems. 

Cement (self-cured)	Adhesive/Primer System	SBS, MPa
NX3	OptiBond Solo Plus	33.2±3.2a*
NX3	OptiBond All-In-One	32.6±5.5a
Nexus 2	OptiBond Solo Plus+Activator	22.6±1.3b
RelyX ARC	Single Bond Plus	19.9±1.8b
Calibra	Prime&Bond NT+Activator	17.8±2.1b,c
Multilink	Primers A+B	17.8±5.3b,c
Variolink	Excite DSC(+Activated brush)	12.0±6.6c
Panavia F2.0	ED Primers A+B	11.2±1.9c

         *Means with different letters are statistically different at p < 0.05.

Conclusions:  NX3 in combination with either a total-etch or a self-etch adhesive produced the highest dentin bond strength among all cementation systems tested.  NX3 exhibited excellent bond compatibility with both total-etch and self-etch adhesives without the need for an activator for the adhesive, resulting in simplified restorative procedures.