Developing And Clinic Study Of Grinding Instrument For Dental Enamel

Fixed orthodontic technique has become more sophisticated after decades of development, especially the use of acid etching and composite adhesive. With enamel acid etching and composite adhesive, various orthodontic appliances can be attached directly to teeth. This makes orthodontic proced-ure easier and more convenient for dentists and patients. However, during enamel acid etching and adhesive removal, irreversible loss of enamel may be caused such as increased roughness which may help the form of dental plaque, calcium loss and hyperpigementation. In recent years, the problem has drawn attention of many researchers and much improvement have been made on adhesion. On one hand, some investigators tried to use crystal formation on the surface of enamel and light-cure resin without enamel-etching, instead of the conventional method with enamel-etching process. All these technique do with the adhesion and may reduce the damage to the enamel. On the other hand, less emphasis was laid on the enamel loss in the process of adhesive removal due to the comparatively less damage and the conventional method was used comprehensively. Using the conventional method, residual adhesive was removed by debonding pliers, hand sealers, green rubber wheels, and other assort rotary instrument attachments. Some studies showed that ultrasonic technique could be used for adhesive removal to provide more convenience and less damage to enamel compared with conventional method.In our study, on the base of the advantage of ultrasonictechnique in enamel grinding, we developed a new enamel grindinginstrument with easily controllable transducer and attachments. With the conventional method as the control, the properties of the instrument was investigated with enamel assay in vitro and in vivo, the effect of it on dental pulp was also determined. Before and after different treatments on the enamel surfaces, our observation were evaluated the enamel surfaces and dental pulp section under digital microscopy and scanning electron microscopy(SEM), and the roughness of enamel surfaces were evaluated. We found that, after different kinds of treatment, the Ra of the treatment group was reduced to 0. 741+ 0. 371 from 0.847 + 0.428, while the Ra of the control group decreased to 0.835 + 0.422 from 0.886+0. 492. Comparing with the control group, the abrasion and the minimal residua on the enamel surface of the treatment group was less, and the enamel appeared to be more clean according to the observation of SEM. Furthermore, the time requirement of the treatment group was 104. 0+9.2s, which was significantly less than that of the control group, 118.4 + 14.9s. So, more efficiency was available. During the whole experiment, no pathological abnormal was observed on dental pulp. Conclusion: Comparing to the conventional method ,the enamel grinding instrument developed by us is more efficiency. It makes enamel surface more clean on adhesive removal. At the same time, it can make patients more comfortable, benefit the remineralization of enamel. So, we assume that it will provide an ideal alternative for enamel polishing and is perspective in clinical use.