The proper test specimens configuration and measuring condition for shear bond strength tests of materials used in removable prosthesis were examined. Specimens of the cylinder-on-disc design produced for shear bond strength tests. Combinations of dental alloy and denture base resin were divided into two groups. One was the METALPRIMER treated group and the other was # 1, 000 emery papar abraded group. Combinations of denture base resin and repair resin were devided into dichrolomethane treated group and final polished group. Half of the cylinders of all specimens were covered with metal tubes to prevent from deformation of materials of the cylinder possibly occured when compressive loads were delivered. The influence of the selected crosshead speed on the nominal shear bond strengths were evaluated. Results showed that in both of a combination of alloy-resin and that of resin-resin, the specimens configuration without metal tubes may be desirable. The nominal shear bond strengths were influenced by selected crosshead speed and the way of the consequences were different among the combinations of materials.
Especially in a combination of resin-resin, an alternative testing method superior than shear bond strength test must be introduced.

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Monkey pulpal responses to metal inlays luted with an experimental resin cement and conventional dental cements were histopathologically evaluated. Initial pulpal responses caused by re-exposure of the cut dentin surfaces and luting procedure were not different between the resin cement and dental cements. There reactions subsided if a tight margimal seal was secured by final cementation of the inlay. The adhesive resin coating of freshly cut dentinal walls/floors seems to provide a new technique to protect the dentin and pulp in indirect restorations requiring temporary sealing.

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Dentin bond strengths are evaluated by conducting mechanical tests in tensile and/or shear mode at a certain level of crosshead speed. According to the literature survey, crosshead speed is varied in a relatively wide rage from 0.1mm/min to 10.0mm/min. It was also found that crosshead speed of 0.5, 1.0, 2.0 and 5.0mm/min were commonly employed in evaluation of dentin bond strengths for both tensile and shear modes, although no rationale for selecting the crosshead speed was described in those reports. Hence the purpose of this study was to investegate the effect of crosshead speed on dentin bond strength.
Two dentin bonding systems, Clearfil Liner Bond 2/ Clearfil AP-X (Kuraray), and Scotchbond Multi-Purpose/Z100 (3M) were employed. Fifteen specimens per test group were tested in a tensile mode in an Instron testing machine at a crosshead speed of 0.1, 0.5, 1.0, 5.0 and 10.0mm/min. In addition, flexural strengths were measured in order to evaluate the effect of crosshead speed on the mechanical porperties of resin composites. The results of this study indicate that there were no strain rate sensitivity when the tensile bond strength test was conducted below the 1.0mm/min crosshead speed. When the crosshead speed exceeded 1.0mm/min, a strain rate dependency of the tensile bond strengths was observed. The strain rate dependency was solely due to the mechanical response from the dentin adhesion interface region.

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Effect of the delayed polishing technique on the rate of sealability between Class V casvity and resin-modified glass ionomer (Fuji II LC, GC; Vitremer, 3M; Photac-Fil, Espe), polyacid-modified composite resin (Dyract, Dentsply Detrey), conventional glass ionomer (Fuji II, GC) and composite (Silux Plus+Scotchdond Multi-Purpose), at both marginal region and bottom region, was studied. Restorations were polished either immediately after light-activation (or setting) or after 1 day storage in water. Determination of the sealability was made on axially sectioned specimens. The shear bond strength to enamel and dentin was performed by the same produst and procedure. Both the rate of sealability and the strength of all products except Dyract, after 1 day storage in water were significant greater than those of immediately after light-activation (or setting).
In the case of Dyract, the case of immediately after light-activation and the case of after 1 day storage in water showed the almsot same value.
It is recommended that the delayed polishing techinque on the resin-modified glass ionomer for filling.

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Opitcal and scanning electron microscopic observations of extracted teeth recorded their histories of restoration were carried out to evaluate several luting cements in vivo. All cases using zinc phosphate cements (ZPC), marginal leakageswere observed. In low caries risk patients, however, secondary caries were not observed. The cases using glass ionomer cements (GIC) were less marginal leakage than ZPC. But in high risk patient, secondary caries were observed at the parts showin gmarginal leakage. All cases using resin bonding cements were observed neither marginal leakage nor secondary caries. SEM observations revealed clear hybridized dentins in every case, even the case of several years passed after cementing. A tag and a hybridized dentin were observed on ground dentin, but no tag formationon the sclerotic dentin just below the caries lesion. It was concluded that the most important point to prevent the secondary caries was reducing the caries risk of patients and using reliable resin bonding system.

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The purpose of this study was to investigate the antibacterial effect after curing of dentine primer incorporating antibacterial monomer methacryloyloxydodecylpyridinium bromide (MDPB). Cured specimens were fabricated in the mould with 5% MDPB-containing primer or control primer, adhesive, and composite. Elution of antibacterial components and inhibitory effect against bacterial growth of cured specimen were determined by agar disc diffusion method. Bactericidal activity of cured primer was evaluated by counting the number of Streptococcus mutans after contact with the specimen for 1 hour and the elution of uncured MDPB was measured. Although experimental and control primers produced no inhibition zones against Streptococcus mutans and Lactobacillus casei, bacterial growth on agar under specimen of MDPB-containing primer was inhibited compared with controls. Both primer produced inhibition zones against Actinomyces viscosus, the size of halo by experimental primer being greater than control. Significantly less bacteria was recovered after contact with experimental primer compared with control, but elution of uncured MDPB was less than the minimum inhibitory concentration value. It can be concluded that dentine primer incorporating MDPB shows inhibitory and bactericidal activity which depend upon immobilized agent even after curing, although a small amount of uncured MDPB eluted also may somewhat inhibit susceptible species such as Actinomyces viscosus.

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Pruritic erythema with serious bleb formation and vesicles was experienced on the finger tips of an dentist who received contact with HEMA or glyceryl methacrylate solutions mediated with rubber gloves approximately 40 times in a period as short as three months. The patch test and the drug lymphocyte stimulation test (DLST) was carried out to examine the possibility of the delayed allergic reaction caused by HEMA solution. Positive reaction was observed by HEMA application in both of the patch test and the DLST where as that for the glyceryl methacrylate solution was diagnosed as the angry back syndrome. Such a positive reaction was observed in also the patch test of a commercially availabledentin bonding agent which contained HEMA and methacrylate esterified with phosphate mediated with deca-methylene chain. Therefore, it was concluded that the methacrylate derivatives required careful manipulation clinically not to sensitize both of the patients and operators.

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For obtainig resistance form and retention form in conventional rules of cavity preparation, it was necessary to extend the cavity outlines until no undermined enamel remains and all the extending fissures or connecting pits and fissures on the occlusal surfaces of the teeth, and to avoid the weakened cavity wall even if they were sound enamel and dentin. However, it should be reconsidered that the high carious resistance of the enamel must bring the teeth longevity.
The recent advances in adhesive dentistry makes it possible that the stable bonding between restorative resin composities and teeth substance could be established by not only mechanical and adhesive retention but also chemical bonding. Moreover, the restorative resin composites are expected to restore the defected teeth and to recover its function, as so-called bio-materials.
In this paper the conservative cavity preparation based on a new concept was proposed to minimize an elimination of the sound enamel and dentin.

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