Generally, self-etching primer contains an acidic monomer, HEMA and water. It has been reported that HEMA is hydrolyzed to ethylene glycol and methacrylic acid in acidic conditions. This hydrolysis is influenced by storage temperature and its duration. The purpose of this study was to evaluate the durability of a one-bottle self-etching primer to determine if the storage conditions of a self-etching primer could influence its tensile bond strengths to dentin. Clearfil MEGABOND (KURARAY) primer was stored in a refrigerator (4°C), at room temperature (23-28°C) and an incubator (37°C). After storage for various periods (1, 2, 4, 8, 12, 24, 36 weeks), a flat bovine dentin surface was applied with the self-etching primer and the adhesive according to the manufacturer's instruction, and then built up with Clearfil AP-X (KURARAY). After 24h in water at 37°C, the specimens were subjected to a tensile force at a crosshead speed of 2mm/min. The statistical analysis was performed using two-way ANOVA and Fisher's PLSD test (p<0.05). Bond strengths of the refrigerator group did not change through the periods, while those of the room temperature and the incubator groups tended to decrease gradually.

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This in vitro study was conducted to evaluate the effect of variations of surface wetness of etched dentin on long-term bonding durability (until one year) and microleakage after thermocycle (5-55°C, 5, 000 times) of Single Bond adhesive system. Etched dentin surfaces after rinsing off the etchant were assigned to following three conditions;(1) Keeping moist by removing excess water by blotting (Wet), (2) Drying for 10s with air-blast (Dry), (3) Drying for 10s and re-moisting by water rinse for 10s and Wet technique (Rewet). For Wet dentin, constant bond strength and fractured dentin surfaces (adhesive failure) were observed throughout all periods and good marginal sealing was obtained. Drying dentin by using air syringe after rinsing off the etchant caused significantly reduced bond strength and degradation of fractured surfaces after one month, and poor marginal seal effectiveness. Re-wetting dentin with water almost re-established bond strength and marginal sealing but degraded dentin surfaces were noted at one year. These findings suggest that Single Bond system exhibits excellent bonding durability and marginal sealing on wet dentin surfaces. Drying dentin surface harms bonding durability and marginal seal effectiveness, and re-wetting with water is not enough to compensate the dryness of dentin surface with air-blast.

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In this study, we measured the shear bond strength of composite resin core material to dentin using convertional and multi-purpose bonding systems.
Actually multi-purpose bonding system included four kinds of dentin bonding systems and they were compared with the conventional one in shear bond strength. In additon, the thickness of composite resin layer was changed in three levels, 2, 4 and 10mm. After measurement of the bond strength, the fracture surfaces of each specimen were observed with the naked eye and classified into four types according to previously arranged criteria.
Then, typical specimens in bond strength and fracture pattern with the thickness of 4mm were examined with scanning electron microscope.
As a result, the thinner the resin core material became, the larger the shear bond strength indicatd in all bonding systems. With the thickness of 2mm, there were no differences in bond strength among 5 bonding systems.
In conclusion, the multi-purpose bonding system, Liner Bond IIΣ, can be evaluated useful as dentin bonding system for the composite resin core material, when cavities were filled by the multi-layer method.

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The purpose of this study was to examine the adhesive property of three kinds of dentin bonding systems to sound versus root caries-infected dentin using a micro-tensile bond strength test (MTBS test) and a scanning electron microscope (SEM). As bonding systems, Xeno CF (X-CF), Fuji Lining Bond LC (F-LC) and AQ Bond (AQ) were used. Freshly-extracted human canines with mild root dentin caries were used in this study, and polished dentin surfaces including the areas which were stained as pink by caries-detector in central occlusal portions surrounded with normal dentin were prepared. Each bonding system was applied to the polished surfaces, and composite resin was built up and polymerized. Dentin specimens with the bonded areas as 1 mm² 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 X-CF could show high bond strengths (about 28MPa) to normal dentin, but that the bond strengths of X-CF to root caries-infected dentin were significantly lower than that to normal dentin. There were no significant differences between the MTBS of F - LC and AQ to normal versus cariesinfected dentin. SEM observation suggested that the hybrid layer formation was inhibited in caries-infected dentin, but that some carious bacteria were embedded with the hybrid layers in some portions of the interfaces.
These results suggested that the adhesion of bonding resins was inhibited by the mud-like structures in caries-infected root dentin.

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When orthodontic metal brackets are bonded to tooth surface with light-curing resin in direct-bonding technique, the light irradiated from the photo-curing unit could not reach directly to the resin under the bracket due to the opacity of metal bracket. Then, to clarify its influence, the author investigated the effects of irradiation time on the degree of conversion of the resin cured under the metal bracket and already reported. The purpose of this study was to evaluate the effect of degree of conversion of bonding resin to bond strength of metal brackets.
The bond strength of metal brackets bonded to bovine enamel with light-curing resin were determined with increase of irradiation time. The bond strength increased proportionally with increase of irradiation time up to 40sec, but did not vary remarkably beyond 40 sec. This result was similar to the variation of degree of conversion of resin cured under metal bracket with increase of irradiation time. There was a strong positive correlation between the bond strength and the degree of conversion of bonding resin.

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The water-soluble bonding agents containing acidic monomer, water soluble photo initiator QTX, tertiary amine, and water-soluble methacrylates were prepared, and evaluated their adhesiveness to tooth. As an acidic monomer, 4-META or MDP was used.
The tensile bond strengths between composite resin and bovine enamel or dentin were measured. The bonding agent containing 4-META gave high bond strengths to enamel with the incorporation of water-soluble dimethacrylate, but did not give high bond strengths to dentin. The bonding agent containing MDP gave high bond strengths to enamel. The MDP bonding agent containing water - soluble dimethacrylates gave the highest bond strengths and formed the hybrid layer with a thickness of 2-3μm between composite resin and dentin.

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Recently there were two luting cements, Chemiace II, Sunmedical; XenoCem, Sankin, commercially available. The objectives of this study were to:(1) investigate the effect of 20, 000thermocycles on the flexural strength and the flexural modulus of the new luting cements; and (2) investigate the marginal gap formation in the dentin cavity and the shear bond strength immediately and after 1-day storage in distilled water of the new luting cements.And it was compared with those of resin-modified glass-ionomer cement for luting (RMGIC) and conventional luting cement (RC).
The values of flexural strength after 20, 000 thermocycles of the two luting cements were between RMGIC and RC.The values of flexural modulus after 20, 000 thermocycles were the lowest of them.Although the values of marginal gap width and bond strength of the two luting cements was between RMGIC and RC immediately, there was no significantly different between them after 1-day storage in water.

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