Long-Term Dentin Bond Strength of Belleglass-NG with New Cementation System

Objective: The use of new self-etch (SE) adhesives and cements has reduced the number of steps and time to place indirect restorations.  In this study, the bond strength (BS) of a new resin cementation system, was evaluated over long-term with Belleglass-NG (BGNG), indirect resin.  Methods:  The cementation system consisted of NX3, an auto-mix, color-stable resin cement and Optibond All-In-One (AIO), a high-strength, one-bottle SE adhesive.  The shear-bond test method has previously been described in J. Dent. Res. V. 80 Abst. #1272, Jan. 2001.  For  the indirect bonding procedure, BGNG Opaceous Dentin cylinders, 3.23 mm dia., were cured in polyethylene tubing following manufacturer's instructions. The surface was sandblasted with 50 micron Alumina at 2 atm., sonified in deionized water, dried and silanated with BGNG Silane Primer.  The prepared teeth (n=48) were wet sanded with 600 grit silicon carbide paper, rinsed with water and lightly air dried.  AIO was applied to the dentin surface  in two coats, thinned uniformly to avoid high spots and light cured for 10 sec. with an Optilux 501 Light (output > 600 mW/cm²).   NX3 was dispensed onto the prepared cylinder surface, which was then seated gently onto the dentin surface.  Excess cement was cleaned off carefully and the margin was light cured for 40 sec.  in 90 deg. sections.  The samples were stored in 37ºC water and a group of 8 random samples was tested at 24 hrs. and periods up to one-year after thermocycling 2,500 X between 5-55ºC.  The mean BS and standard deviations (s.d.) were calculated and analyzed with Anova (p<0.05).  Results:  The mean BS and s.d. are given in the table.  The BS remained high with no significant differences between the means at each period.  Conclusion:  After one-year, the BS of BGNG with the new resin cementation system remained stable (funded by Kerr Corp.).

Mean Shear Bond Strength, MPa (s.d)
24 Hrs.	One-Wk.	One-Mo.	Three-Mo.	Six-Mo.	One-Yr.
31.2 (4.8)	30.9 (6.1)	31.0 (4.2)	25.0 (6.2)	24.1 (7.8)	29.2 (5.7)