金属線によるレジン床の補強に関する基礎的研究

抄録

Acrylic resin has been most commonly used for denture base. It will be more satisfactory in clinical performance if the denture can be made thinner, since the thicker denture often causes discomfort and/or speech disturbance of the patient. Resin base cannot be made thinner without liability to fracture. Metal strengthener has long been used to reinforce the acrylic resin denture. In the present paper the effect of embedded metal strengthener was reviewed on the bending strength for the rectangular rod-shaped resin specimen. Wires highly resistant to distortion against applied force exhibited higher reinforcing effect. Bending strength increased significantly by embedding the strengthener at the compression side on bending of the specimen. No effects were found when it was embedded at the center or the neutral axis. The highest reinforcing effect could be obtained when 18-8 stainless steel palatal bar lay at the tension side. At this side, reinforcing effect of the bar was extremely enhanced for the specimen having a U-shaped notch at the same side, whilst no significant effects of the bar at the compression side could be seen for notched specimen. Another advantage of embedding a bar at the tension side was that the deterioration of the bending strength by fatigue was much delayed to occur. From these facts together with the fact mentioned later, the best reinforcing effect on upper resin full denture can be expected by embedding a bar near the lingual surface along the dental arch, provided an anterior interdental portion might act as a notch and the fracture of the denture occur by bending through there. Observation of the distortion of upper full denture during chewing foods revealed that the resin denture was deflected laterally by bending in the manner that the lingual side of the palate was subjected to tension. The deflection of the palate of the denture with a bar at the site mentioned above was dropped to about one third of that of the denture without any strengthener.