The dental adhesives applied now in Japan, using 4-META or Phenyl-P as an adhesivepromoting monomer, have extremely strong adhesion. Since desirable adhesion to dentin or precious alloys cannot be expected, however, new studies are being made on such adhesivepromoting monomers.
The application of etching or primer as a pretreatment to the adherends is an indispensable auxiliary means for bonding.
A pretreatment now recommended for each adherend is as follows; etching using a 30-60% phosphoric acid solution for enamel; etching with a solution of citric acid weaker than phosphoric acid for dentin, which has recently been replaced by etching with a sodium hypochlorite solution; formation of thin oxide film. sand blasting or silane coupling for an alloy; both etching with fluoric acid and silane coupling for ceramics such as porcelain veneer.

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We evaluated the adhesion between a composite resin and tooth substances promoted by Liner Bond II (Kuraray, Japan). Tensile bond strength was measured after long-term storage in water or thermocycles. In addition we studied the effect of the thickness of bonding layer on adhesion to tooth substances.
The results were as follows:
1. Liner Bond II showed high tensile bond strength to both enamel and dentin.
2. The long-term storage in water did not affect the bond strength.
3. Thermocycles decreased the bond strength, however the specimens were failed in the bonding layer which bonded to the tooth substances tightly.
We concluded that Liner bond II was excellent bonding system.

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There are many etiological reports about the occurrence of wedge-shaped defect. A lot of reports have been cited toothbrush abrasion as the possible cause of wedge-shaped defect. Recently, a hypothesis that occlusal stress on teeth is the major factor that initiates wedge-shaped cervical lesions was reported. This hypothesis says that the primary etiologic factor in cervical erosion is the tensile stress caused by mastication and malocclusion. The term “abfraction” has been used as this lesion defect. Wedge-shaped defects are restored with composites or glass-ionomer cements generally. In case of restoration for wedge-shaped defects, we should understand materials factors and tooth factors, as well as occlusal factors joinly.

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In this study, we investigated water sorption of dual-curable adhesive cements. Water sorption, solubility and diffusion coefficients were determined on seven commercial dual-curable adhesive cements. The water sorption of five discs of each material were measured after immersion in 37°C water daily over the first seven days, weekly over the next three weeks and monthly thereafter until three months. After the three months immersion the specimens were dried in desiccator. Solubility were determined from the change of weight before immersion and after drying. True water sorption values at three months were obtained by adding the solubility values to the corresponding water sorption values at three months. Diffusion coefficients in dual-curable adhesive cements were obtained using Crank's method.
The results were indicated as follows;
1. Diffusion coefficients of water in dual-curable adhesive cements were smaller than those in dental composites.
2. Linear regression was not attained between filler content and water sorption.
3. Linear regression was attained between solubility and diffusion coefficient. It is suggested that diffusion coefficient is important factor for durability of dual-curable adhesive cements.

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