The aim of this in vitro study was to investigate polymerization reactions of the self-etching primer bondingsystem (Clearfil Mega Bond, Kuraray) using electron spin resonance spectroscopy (ESR). The sample was dividedinto three groups: bonding agent alone (B), bonding agent with self-etching primer (B-P), and bonding agent withair-dried self-etching primer (B-AP). Each sample was placed in the quartz ESR flat cell and was irradiated for1min (Solidilite, Shofu). Radical concentrations were recorded at an interval of1min for20min. A characteristic “5+4-line” spectrum, which indicates the presence of a polymerization radical from the methacryl derivatives inall groups, was observed. The average value of the maximum radical concentration of B-P (1.47±0.14×10^-4M) was significantly lower than B (3.64±0.44×10^-4M) and B-AP (3.47±0.30×10^-4M)(p<0.01). According to theresults of this study, it was recommended that the self-etching primer should be strongly air-blown, because of thevolatile solvent in self-etching primer might acts as a polymerization inhibiter for the bonding agent.

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MI concept has been propagated clinically according to the advancement of the adhesive materials and tounderstanding of the caries development. MI diamond points were designed based on this concept to remove theinfected lesions thoroughly, preventing the cavities from extension beyond the sound tooth tissues. The aim of thisstudy was to introduce and evaluate the clinical performance of the experimental MI diamond points, which couldbe expected to totally support the adhesive restorations procedures. This MI diamond point system consists of thepreparation and the finishing & polishing kits. The preparation kit comprises three sizes of round-type long-neckpoint and three sizes of pear-shaped long-neck point. As a result, these points were very useful due to the smallcutting head to remove the active lesions only preserving the sound tooth tissues, to the long neck to access to thedeeper cavity floor visibly, and to the strong mechanical property that did not cause the neck fracture of pointbody. Further, the finishing & polishing kit, consisting of the eight kinds of smooth-cut finishing points and thesilicone point “compo-master” for polishing, could be available for almost all cases of finishing procedures of theadhesive restorations and could contribute to shorten the treatment time.

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Resin-bonded fixed partial denture has an advantage of minimum tooth tissue reduction on preparation compar-ed to conventional retainer, such as full cast crown. However, when the shape of abutment tooth or bondingprocedure is not suitable, the bonded bridge may fail in relatively short-term in oral environment. Therefore, weplanned a fundamental practice for the purpose of education that undergraduate students of our dental school learnbasic skill in tooth preparation and bonding procedure. This practice was conducted on 60 students of five yearsdegree. First, the thickness of enamel was measured on the cross sectional surface of natural tooth specimens witha vernier micrometer. Then artificial teeth were drilled on the assumption of anterior and posterior bridges. Theretainer design was determined in terms of the five principles, such that minimum enamel was removed. Allstudents completed the tooth preparation, and then made resin pattern of the retainer on it. In addition to thetechnique to use the bonding system, they experienced with feeling adhesive force between metal and adhesiveresin. Following surface treatment, a prefabricated metal framework was bonded to a jaw model with an adhesiveresin. It is considered that the present practice was useful for the students to acquire the skill for the dentaltreatment with resin-bonded fixed partial denture.

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The aim of this study was to examine the interfacial ultrastructure between the bonding resin and pulpal dentin surface of the human extracted teeth under the FE-SEM after Ar ion-beam etching with a newly designed onestep dual-cured bonding system (Kuraray Med. Co.). The adhesion between the resin and inner dentin surface was very tight and no gap was observed under the SEM.
It was suggested that the brand-new system will be promising for composite core restorations.

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A newly designed dual-cured resin bonding and a resin composite system for core build-up have been developed by Dentsply Sankin Co., Ltd. The purpose of this study was to observe the interfacial ultrastructure under the FESEM after the Ar-ion beam etching for35s using the inner dentin surfaces. In addition, clinical procedure using a newly developed light-tip system for irradiation was introduced. SEM observation demonstrated that the interfacial junction between the dual-cured adhesive and inner dentin surface was very tight and no gap formed. It was suggested that the brand-new system would be promising as a direct core build-up system for the next generation.

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The purpose of this study was to evaluate the influence of light intensity on dentin bond strengths of single-step self-etch adhesive systems; AQ Bond Plus (AQ), Fluoro Bond Shake One (FB) and One-Up Bond F Plus (OF). Twostep adhesive systems, Mac-Bond II (MB) and Single Bond (SB), were used as controls. Bovine incisors were mounted in self-curing acrylic resins and facial surfaces were wet ground to expose flat dentin. Dentin surface was treated with each adhesive system and the adhesives were irradiated with light intensity of 100, 300, 600 or 900 mW/cm². Shear bond strength was measured after storage in water for 24 h at a cross-head speed of 1.0 mm/min. Resin-dentin interfaces were observed with SEM. Dentin bond strengths ranged from 11.3 to 13.2 MPa for AQ, from 15.9 to 17.1 MPa for FB, from 11.2 to 13.7 MPa for OF, from 13.0 to 16.4 MPa for MB and from 11.5 to 15.8 MPa for SB. The dentin bond strength of single-step self-etch adhesive systems was not affected by the difference of light intensity. Significant lower bond strengths were obtained for two-step systems when irradiated with the light intensity of 100 mW/cm². Results of this study indicated that the single-step self-etch systems were not influenced by the difference of light intensity.

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In case of applying the adhesive restoration to proximal caries treatment, the key element to be concerned is the adhesion of sub-gingival margins. The main reason of the consideration is the technical failure at the infected adhesion area caused by gingival fluid and/or bleeding that will leads the cavity to immediate cold-water-pain and also unstable prognosis in the long run. Thus, the writer has been controlling these infection factors at sub-gingival margins by adapting CO₂ laser. And recently, the writer adapted the new approach to cavity treatments combining three methods such as conventional rotary instrument, airbrasion and CO₂ laser to minimize the intervention. This approach not only meets the idea of Minimal Intervention, but also keeps free enamels at the marginalline to have more precise adhesion. Kept free enamels were etched with phosphoric acid and dried by thoroughly with a CO₂ laser and mirror technique. And then, an adhesive agent and a flow-able resin composite will be applied for the cavity filling in this part (Reinforced free-enamel method). When the adhesion to enamel at sub-gingival is obtained, we can expect for higher bonding strength, better prognosis in the long run than the adhesion to dentin. Taking this occasion, I would like to introduce you the technique.

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