The need for a restorative material which lends itself readily to the cosmetic match ing of tooth structure is great. Such a material, to be ideal, must have also the physical characteristics necessary for the replacement of lost tooth structure and for the prevention of dental caries. There is basis for the hope that the resins will develop into such a material. The history and the development of acrylic resins have been covered in other papers; therefore, this paper is devoted to their clinical evaluation. Since the physical properties of the heat-processed acrylic resins do not differ fundamentally from the auto-polymerizing resins, the use of the former for the making of jacket crowns, facings and bridge prostheses will be considered also.1’ 2 While maintaining their regard for the time-tested materials and technics, at the same time dentists should look forward to the perfecting of other materials which will be developed in the future; that is, the old should not be thoughtlessly dis carded simply because it is old nor should the new be rejected solely because it is new. This philosophy prompted the author to begin a clinical investigation of the plastics in 1949. The resins used in restorative dentistry are still in the re search phase and must be re-evaluated from time to time as they are improved and developed. In order to obtain current data for the evaluation of resin as a restorative material, both in crown and bridge pros thesis and in operative dentistry, a broad and inclusive questionnaire was prepared and sent to one hundred well-known practicing dentists. Ninety-six per cent of these questionnaires were completed and returned. While it is fully realized that a ques tionnaire seldom can take the place of responsible research, nevertheless, this questionnaire is significant because it reflects the total clinical experience of this group. The best test of any restora tive material is its ability to render service in the mouth. The practitioner’s experi ence obviously is a valuable indicator of that ability. In response to the first question, “ Have you used heat-processed plastics in bridge construction?” approximately 90 per cent of the dentists responded in the affirma tive. In reply to the second question, “ Were the plastic portions stress bearing?” 40 per cent replied in the affirmative. The comments accompanying the replies to