Influence of cold working and thermal treatment on the fit of implant-supported metal-ceramic fixed partial dentures☆1☆2☆3☆4☆5☆6☆7☆8
Abstract
Statement of Problem. The application of porcelain may alter the fit of metal-ceramic frameworks. In fixed partial denture frameworks, this altered fit may cause marginal opening and require sectioning and soldering of the prosthesis. Purpose. The purpose of this study was to compare the fit of implant-supported metal-ceramic fixed partial dentures when different thermal treatments were performed. Material and Methods. Fifteen implant-supported metal-ceramic fixed partial denture frameworks were fabricated and divided into 3 treatment groups: Group 1 = cold working and thermal oxidation; Group 2 = unrestrained thermal treatment, cold working, and oxidation; and Group 3 = investment-restrained thermal treatment, cold working, and oxidation. After the appropriate treatment procedures, porcelain was applied. Measurements were made with a digital caliper, with the help of fiduciary marks, after each step in 3 dimensions and at 2 locations. These measurements were compared with those of the as-cast framework (baseline) to determine framework distortion. Distortion data among groups were compared with repeated-measures analysis of variance and Tukey's Studentized range test (P<.05). Results. Absolute values of distortion (regardless of direction) after thermal treatment and after porcelain application were not significantly different among groups. However, total raw values of distortion, which describe the specific direction of distortion, were significantly different for 4 of the 6 recorded measurements between Groups 1 and 3 (P<.05). Although the absolute distortion values did not differ among groups, heat treatment and finishing of the alloy affected the timing and direction of distortion. Conclusion. Within the limitations of this study, heat treatment of implant-supported metal-ceramic fixed partial denture frameworks before cold working did not decrease the total absolute distortion. Definite patterns of distortion were, however, found in Groups 1 and 3, suggesting that specific manipulations and heat treatments of the alloy affected the direction of distortion. (J Prosthet Dent 2002;88:159-69.)
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☆1 Reprint requests to: Dr Carlo Ercoli, Division of Prosthodontics, University of Rochester Eastman Dental Center, 625 Elmwood Ave, Rochester NY 14620, Fax: (716)244-8772, E-mail: carlo_ercoli@urmc.rochester.edu
☆2 This research won the First Place 2000 Stanley D. Tylman Research Award from the American Academy of Fixed Prosthodontics and the 1999 Granger-Pruden Memorial Award from the Northeastern Gnathological Society.
☆3 This study was supported in part by a 1999 Stanley D. Tylman Research Grant from the American Academy of Fixed Prosthodontics.
☆4 aFormer Resident, Division of Prosthodontics. Fellow, Maxillofacial Prosthetics and Dental Oncology, M.D. Anderson Cancer Center, Houston, Texas.
☆5 bAssistant Professor and Program Director, Division of Prosthodontics.
☆6 cAssistant Professor, Division of Oral Sciences.
☆7 dProfessor and Chief, Division of Prosthodontics.
☆8 eDirector, Temporomandibular Joint Dysfunction Program, and Professor, Division of Prosthodontics and Orthodontics.
PII: S0022-3913(02)00073-2
doi:10.1067/mpr.2002.127592
© 2002 Editorial Council of The Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.
