We have chosen five commercially available adhesive resins, Super-Bond C&B (SB), SB for opaque resin (SBO), Panavia 21 (PV), Bistite II (BR) and Imperva Dual (ID), and investigated on their tensile adhesive strength (σ_t) and fracture toughness (G_IC), and δ_t and G_IC after 4/60°C themal-cycling for evaluating a durability, comparatively. The adherend used was a non-precious metal. The major findings were as follows. No great difference in σ_t of SB, SBO, PV, BR and ID was recognized. But, in G_IC, the value (G_IC= 592J/m²) of SB without filler was 9 to 14 times as many as that of PV, BR and ID with filler. In all adhesive resins, by thermal-cycling test, their adhesive strengthes were not affected very much. And their fracture modes were observed as cohesive fracture. Next, in fracture toughness after thermal-cycling, the values of PV, BR and ID showed 4 to 31 percent decrease in order of the symbolized adhesives, and the value of SB notably lowered and showed 86 percent decrease. And the fracture mode of SB changed to interfacial fracture. These results revealed that a mechanical property after thermal-cycling was affected considerably by a size of test specimen, therefore, there is the possibility that we evaluate the durability of adhesive resin by mistake.

View full abstract

The anticariogenicity of a new adhesive resin cement containing fluoride was evaluated by making artificial secondary caries in the cervical areas of full cast crowns. The full cast crowns were luted on human maxillary premolars in vitro. The depths of the demineralized areas were measured. The results of three months observation indicated that the new adhesive resin cement containing fluoride was anticariogenic because of the existence of an inhibition layer. The results of this experiment also showed that the new resin cement had adhesive durability. Further basic investigation is needed to evaluate fluoride release from luting cement and its absorption by dentin.

View full abstract

The purpose of this study was to examine the adhesive property of three kinds of self-etching bonding systems to sound versus caries-infected dentin using a micro-tensile bond strength test (MTBS test) and a scanning electron microscope (SEM). As bonding systems, Clearfil Mega Bond (MB), Unifil Bond (UB) and Imperva Fluoro Bond (FB) were used. Freshly-extracted human molars with mild dentin caries were used in this study, and polished dentin surfaces including the areas which were staind as slightly-pink by caries-detector in central occlusal portions surrounded with normal dentin were prepared. Each bonding system was applied to the polished surfaces, and Clearfil AP-X composite was built up and porimerized. Dentin specimens with the bonded areas as 1mm² were prepared from the resin-bonded teeth, and subjected to MTBS test. The other resin-bonded teeth were subjected to SEM observation. The result of the MTBS test revealed that all of the bonding systems could show high bond strengths more than 30 MPa to normal dentin, but that the bond strengths of all systems to caries-infected dentin were significantly lower than that to normal dentin. SEM observation suggested that the hybrid layer formation was inhibited in caries-infected dentin.

View full abstract

The purpose of this study was to evaluate the efficacy of an air polishing using crystalline cellulose abrasive particles on removal of temporary filling materials on a resin composite, Clearfil Photocore (PC, Kuraray, Japan), for core build up. In addition, the bond strengths of resin cement, Superbond C&B (SB, Sun Medical, Japan), to PC after air polishing was investigated. Five commercially available temporary filling materials; Temporary Pack (GC, Tokyo, Japan), Plast Seal (Nippon Shika Yakuhin, Japan), Seal In One (Nippon Shika Yakuhin, Japan), HY-Bond Temporary Cement (Shofu, Japan), and Cavit-G (ESPE, Germany), and one experimental zinc oxide eugenol cement (Nippon Shika Yakuhin, Japan) were used. The SEM observation of the air-polished composite surface indicated that the crystalline cellulose abrasive particles hardly damaged the composite surfaces, and could completely remove the temporary filling material on the composite. The results of the tensile bond test indicated that the bond strengths of SB to PC after removal of temporary filling materials with air polishing were the same values as the control (23 MPa). These findings supported that the air polishing with crystalline cellulose particles could be very useful to clean composite surfaces contaminated from temporary filling materials.

View full abstract

Resin-coating technique is unique to produce tight sealing film on the dentin surface with an adhesive resin and a low viscosity composite. For indirect restoration, it enables us to cover prepared surface immediately after preparation to minimize further pulp irritation from mechanical, thermal and bacterial insults during impression taking, temporary restoration, and final cementation. In this study, the influences of residual monomer on resin-coated dentin and also two types of impression materials on bond strengths of resin cement to resin-coated dentin were evaluated. The impression materials used in this study were reversible hydrocolloid (Aromaroid, GC) and silicone rubber (Exafine, GC). Clearfil Linerbond IIΣ and Protect Liner F (Kuraray, Osaka, Japan) were applied to bovine dentin to make a substrate. The resin cement, Clapearl DC (Kuraray, Japan) was cemented on resin-coated dentin. Tensile bond strength was measured at crosshead speed of 2 mm/min. The results indicated that reversible hydrocolloid did not influence the bond strengths of resin cement to resin-coated dentin, whereas silicone rubber ruduced the bond strengths. However, after impression taking, the bond strength recoverd when the contaminant from impression materials was wipe off with an alcohol cotton pellet. In conclusion, the use of reversibie hydrocolloid is proper for resin-coating technique.

View full abstract

Recently, two-step type simplified bonding systems have been introduced on the market. In this study, we observed the interfacial ultrastructure between the intact teeth or caries-affected dentin and resin composite with dual cure type resin bonding system “Super Bond D Liner Dual” by using SEM.
A tight adhesion between resin and tooth tissues was obtained, and the hybrid layer about 2-3μm thick was observed at the interface between dentin and bonding resin.
Additionally, when we applied this system to the resin composite restoration of the anterior cavities in clinic with Metafil C resin composite, we could obtain satisfying restorations.

View full abstract

The purpose of this study was to evaluate the effect of dentin preparation with burs of differnt types and grids on tensile bond strength using three self-etching priming systems (Clearfil Liner Bond II (LBII, Kuraray), Clearfil Liner Bond IIΣ(IIΣ, Kuraray), and Clearfil MEGABOND (MEGA, Kuraray)). The occlusal enamel of thirty-six extracted intact human molars were removed perpendicular to the long axis of the teeth. After the dentin surfaces were polished with #600 SiC paper, the teeth were divided into 4 groups according to bur type and grit: fine cut steel bur (SB600), cross cut steel bur (SB703), regular grid diamond point (DP), and without bur cutting for control (AP#600). The dentin surfaces of each group were cut with the burs which were mounted in a dental handpiece under copious air-water spray. They were treated with one of the three adhesive systems, then composite buildups done with Clearfil AP-X (Kuraray). After 24h in water at 37°C, the resin-bonded teeth were serially sliced perpendicular to the adhesive surface, the adhesive interface trimmed to a cross sectional area of 1 mm², and subjected to tensile forces at a crosshead speed of 1 mm/min. The statistical analysis was made using one-way ANOVA and Fisher's PLSD test. Bond strengths from highest to lowest were AP #600, SB600, SB703, DP, in order. This tendency reached statistical significance using IIΣ.

View full abstract

In cervical restoration, the resin-dentin interface is subjected to repeated shear stresses caused by the different Young's moduli of the tooth and the materials through occlusion. Evaluating the dynamic fatigue characteristics of the resin-dentin interface in vitro may estimate the long-term success of resin restorations. The purpose of the present study was to evaluate the influence of different curing types (Liner Bond IIΣ: light-cure and dual-cure) on the fatigue resistance of the adhesive interface. Average shear bond strength obtained from the dual-cure (23.1MPa) is significantly higher than that of the light-cure (17.9MPa). Also, the estimated fatigue limit of the dual-cure was superior to that of the light-cure. From EPMA analysis, the dynamic fatigue cracks of the dual-cure mainly propagated through the base of the hybrid layer, where Ca content is rather high.
With respect to the dual-curing system, an increased degree of conversion rate might lead to enhanced cross-linking of the monomer which impregnated the front of the hybrid layer and contributed to improvement in the fatigue limit of the adhesive interface. These results may predict the clinical long-term success of the dual-curing bonding system.

View full abstract

The bond strengths of orthodontic mesh brackets with one commercial (LC) and one experimental (EX) light-cured glass ionomer cements to etched (10% polyacrylic acid) and polished human premolar enamel contaminated with water, and saliva before and after thermal cycling were measured to investigate bonding durability. No significant differences were found in bond strengths (5.7-8.5MPa) to unetched enamel after immersion in water for 24h among types of materials or among types of contaminants (p>0.05). All brackets were left out unetched enamel after thermal cycling. For etched enamel, no significant differences were found in bond strengths of EX (8.5-9.5MPa) after immersion in water for 24h among types of materials or among types of contaminants (p>0.05). The bond strengths (12.0 MPa and 11.9 MPa) of LC to water-contaminated and uncontaminated enamel were higher than that (8.2 MPa) to saliva-contaminated enamel. Although thermal cycling significantly (p<0.05) decreased all bond strengths (4.5-7.6MPa), no significant differences were found in bond strength, except for that (4.6 MPa) of LC to saliva-contaminated enamel, among types of materials or among types of contaminants (p>0.05). SEM micrographs revealed that all samples after bonding test had mixed cohesive and cement-enamel interface failures. Polishing technique, saliva contaminant and thermal cycling increased cement-enamel interface failure.

View full abstract

In an attempt to evaluate the consistency of resin-dentin bonds, Shono (1999) have developed a new version of microtensile bond test method that permit evaluating regional tensile bond strength across entire bonded surfaces. In this studies, the new version of microtensile bond test was used to evaluate the regional bond strengths of six commercially available dentin bonding systems to dentin. The purpose of this study was to test the hypothese that there is no regional difference in the dentin bond strength.
As the results, the commercially available adhesive resins bonded well to dentin but compared to the control group of resin bonded to resin specimens there have a widely standard deviation. Almost the failures were classified as adhesive in nature by using the new version of microtensile test method. There have a tendency that wet bonding system shown higher microtensile dentin bond strength than that of self-etching system. The results obtained in this study require rejection of the hypothese that there was no regional difference in the dentin bond strength. The newly developed test method is very useful for evaluating regional tensile bond strength tests across entire bonded surfaces. This type of information is much more meaningful than the single measurements made with conventional resin composite bond strength tests.

View full abstract