Abstract
The system used for cast-plate construction at the Nihon University Dental Hospital was developed by Shofu, Inc. (Japan). The duplicating hydro-colloid material, the hydro-colloid duplicating dispenser, the refractory cast material, the Co-Cr alloy and the casting machines are all supplied by Shofu, Inc. While 100 to 150 cast plates are made a year, swaged metal plates are not made at all.
Cast plates used at the Hostipal, therefore, are limited in the method of construction, the number of plates and the system of application. Because of this, an assessment of the existing state of metal plate construction in the country was sought by means of a survey of dental laboratories since these make almost all the metal plates for patients attending private dental clinics.
Answers from 34 laboratories were analyzed and tabulated as below.
1. The percentage of laboratories making less than 999 metal plates a year was the highest at 47.8%, and the highest number of plates made in a year at any one laboratory was 12, 600.
2. The percentage of laboratories making less than 500 full metal plates a year was 66.7% of the total, the highest.
3. The percentage of laboratories making less than 1, 000 partial metal plates a year was 60.9% of the total, the highest.
4. The ratio of the number of partial metal plates to the total number of metal plates constructed a year at any one laboratory ranged from 70 to 79% at 7 laboratories or 27% of the total, the highest.
5. It was shown that a greater number of laboratories used implements and materials from various makers in constructing their metal plates rather than limiting their suppliers to a single maker.
