Synthesis of a novel functional monomer and development of an adhesive system appropriate to laser-irradiated dental tissues

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Introduction: The use of Er:YAG laser for catty preparations during treatment of dental caries has received attention because there is no unpleasantness of noise and vibration as with air turbine and micromotor, and there is no need of anesthesia for treatment. However, we found that conventional dental adhesive systems do not perform sufficiently well on Er:YAG laser irradiated dental surfaces, and moreover, one of its reasons is the weakness of dental surfaces after laser irradiation. So, due to its importance and clinical significance, we aimed to clarify the dental structure after Er:YAG laser irradiation and its quality as an adhesive surface, along with the development of a new adhesive system appropriate to this surface.Materials and Methods: 1) Adhesive surfaces preparation: Er:YAG laser (Erwin, Morita Co.) was irradiated with 127mJ, 10pps for 2 sec for enamel and with 69mJ, 10pps for 2 sec for dentin. 2) The primers of the adhesive systems were prepared with triazine-, aminoac … More id-, and epoxy-methacrylate/HEMA and alcohol. 3) The adhesive surfaces above were treated with each type of primer, phosphoric acid esther bonding agent and filled with composite resin (Clearfil APX, Kuraray Co.), then immersed in water at 37□for 24 hours before bond strength measurements.Results and Discussion: The bond strength of epoxy type primer system to Er:YAG laser irradiated dental adhesive surfaces was 18.6MPa for enamel (control: Megabond/Kuraray Co.; 12MPa), and 17.2MPa for dentin (control: 9MPa). The authors say that these results may be due to oxygen that exists in the space created by microcracks that occurred during laser irradiation of dental adhesive surfaces. As conventional dental adhesives, used in the control group, are of radical polymerization type, the polymerization reaction decrease remarkably in the presence of oxygen. On the other hand, the ring opening polymerization type resin tested in this study may be not much influenced by the presence of oxygen during reaction. Less