Clearfil DC Bond (DC) is a new singlestep, dual-cure bonding agent. In this study, the shear bond strengths of a core build-up composite to dentin used with four bonding systems [DC, Unifil Core SelfEtching Bond (UC), Clearfil SE Bond (SE) and Cleafil tri-S Bond (TS)] were measured. The bonding ability after 7 days of storage and in vitro durability following 20,000 thermocycles were also evaluated. The bond strength of DC did not differ significantly from those of other bonding systems after 24 hours of storage. Another dual-cure bonding system, UC, showed a significant reduction of bond strength after 7 days of storage. On the other hand, the bond strength of TS, a light-cured bonding system with a similar composition to DC, was reduced significantly following 20,000 thermocycles. SE, a two-step light-cure bonding system in the same series as DC, provided superior bond strength under all conditions. Although DC showed a slightly lower bond strength than SE, there was no significant difference between DC and SE under all conditions. Consequently, DC may be a useful and effective bonding system for multiple composite resin restorations. (J. Oral Sci. 50, 329-333, 2008)Keywords: dual-cure; single-step; self-etching; bond strength; bonding system. IntroductionVarious bonding systems with improved bonding characteristics that are easy to use have been developed. Recently, self-etching adhesive systems have been widely used for bonding to dentin substrates because of their superior bond strength and reduced technique sensitivity (1-3). These systems simultaneously demineralize and penetrate resin monomer into dentin without the rinsing and drying step (4,5). Currently, single-step self-etching systems, which combine the three steps of etching, priming and bonding in a single application, with no need to rewet the dentin surface or re-expand the shrunken collagen network, have been proposed as suitable agents for dentin bonding (6).Clearfil DC Bond (DC; Kuraray Medical Inc., Tokyo, Japan) is a new self-etching, two-bottle/single-step, dualcure bonding agent. According to the manufacturer's instructions, the clinical indications include core build-ups, direct restorations, and cavity sealing as a pretreatment for indirect restorations. In this study, the shear bond strengths of a core build-up composite to dentin using four bonding systems, including DC, were measured. The bonding ability after 7 days of storage and in vitro durability following 20,000 thermocycles were evaluated. Materials and MethodsPreparation of bonded specimens A total of 96 bovine mandibular incisors were used as dentin specimens. The facial surface was ground with a rotary cutting instrument to expose the coronal dentin surface, which was then embedded in an aluminum mold

The aim of this study was to evaluate in vitro the shear bond strength to a gold alloy of RMGICs combined with three metal priming agents. Gold alloy was primed with one of the following materials: Alloy Primer, Metal Primer II, or Metaltite. Non-treated group was considered as the control. Specimens were bonded with one of the following luting agents: Super-Bond C&B, Vitremer Luting Cement, Fuji Lute, or Xeno Cem Plus. Shear bond strength was then determined. The bond strengths of resin-modified glass ionomer cements primed with the metal priming agents were greater than that of non-treated group, except for the Vitremer Luting Cement-Alloy Primer combination. It was thus concluded that the priming agents employed in this study were substantially effective in improving the bonding of resin-modified glass ionomer cements to gold alloy.

The shear bond strength of a veneering composite (Solidex) and silver-palladium-copper-gold alloy (Castwell M.C.12) was evaluated for different duration times and irradiance for preliminary photo-polymerization. A veneering composite was applied onto a cast disk. Preliminary photo irradiation was performed using different duration times or irradiance. After final polymerization, the bond strength and the spectral distribution of each curing unit were determined. Shear bond strength was significantly higher for 90 s (12.4 MPa), than that for 0 s (8.3 MPa). With regard to the effect of irradiance, that from Solidilite (11.4 MPa) was significantly higher than that from Sublite S at 3 cm (8.7 MPa). The irradiance of Hyper LII and Sublite S at 3 cm was higher than Sublite S at 15 cm or Solidilite unit. Long time irradiation and low intensity is effective for preliminary irradiation in order to enhance the bond strength.

This study evaluated the influence of water storage conditions and the effect of metal priming agents on bond strength and durability of four luting agents joined to gold alloy. Disk specimens were cast from a gold alloy (Degudent U), and the surfaces were ground flat with abrasive paper. Three surface conditions employed were: unprimed, primed with Alloy Primer, and primed with Metaltite. Three resin-modified glass ionomers (RMGIs; Vitremer Luting Cement, Fuji Lute, and Xeno Cem Plus) and a resin adhesive (Super-Bond C&B) were used for bonding the gold alloy. Unprimed specimens bonded either with Fuji Lute or with Super-Bond C&B were immersed in water at 5, 37, and 55 degrees C for 7 days, or subjected to thermocycling (5,000 cycles; 5 degrees C, 1 min and 55 degrees C, 1 min). In addition, specimens were bonded with 12 combinations comprising three surface conditions and four luting agents, and thermocycled for 20,000 cycles. Shear bond strengths were then determined and analyzed statistically. Thermocycling was useful for evaluation of the bonding durability of RMGIs. Application of two metal priming agents combined with RMGIs considerably enhanced the bond strength to the gold alloy.