A comparison of the accuracy of torch soldering, laser welding, and casting in one piece for implant-supported fixed partial dentures
Date
1996
DOI
Authors
Sudhinaraset, Pornphan
Version
OA Version
Citation
Abstract
Accuracy of fit and adequacy of strength are major concerns for implant supported fixed partial dentures (ISFPDs). The first objective of this study was to measure the relative accuracy of four-unit, ISFPDs that have been joined by using: (1) soldering with a torch, (2) laser welding, and (3) casting in one piece. The second objective was to evaluate the strength of the joints of rectangular alloy bar specimens that have been joined by using the same methods as described above.
Part I
Four-unit ISFPDs were used as samples in this part of the study. A group of five ISFPDs was indexed and connected with conventional torch soldering. A second group of five castings was laser-welded. A third group of five solid, one-piece, cast ISFPDs served as controls. The ISFPDs were cast from a palladium alloy that includes palladium 78 %, gold 2% (ULTIMA gold, J.M. Ney Corp., Bloomfield, CT). The solder recommended by the manufacturer for a palladium alloy (Ney 2 white, J.M. Ney Corp.) was used. Soldered ISFPDs were indexed on the working model with the use of a cyanoacrylate adhesive (Zaplt, Dental Ventures of America, Inc., Anaheim Hills, CA), then attached to soldering analogs (31, West Palm Beach, FL) and invested in a conventional soldering investment (Hi Heat, Whip Mix Corp., Louisville, KY). Laser welded ISFPDs were welded directly on the working models with the use of a laser welding machine (Laser Welder, Exel Technology, Inc., Hauppauge, NY). One-piece castings were also fabricated on the working model. Each four-unit ISFPD was firmly attached to the master model with the use of implant screws (31) and a torque-controlled wrench (31). Accuracy of the fit of each ISFPD was compared by measuring the gap distances between the laboratory analogue and gold coping interface at predetermined points with the use of a video micrometer (JV 6000. Javelin System Inc., Torrance CA) before and after connecting the two gold cylinders. The values obtained were subjected to an analysis of variance (ANOVA). Results indicated statistically significant differences in the marginal gap distances between the soldered group, laser-welded group and one piece group (p[less than] 0.01). Mean marginal gap distance and standard deviation for the soldered group was 53.60 ± 23.2677 [mu]m., mean marginal gap distance and standard deviations for the laser-welded group was 8.7920 ± 1.8070 [mu]m., and mean marginal gap distance and standard deviation for the one-piece casting group was 79.8160 ± 7.0575 [mu]m.
Part II
Thirty rectangular bars were cast from a palladium alloy that includes palladium 78%, gold 2% (ULTIMA gold, J.M. Ney Corp.) and divided into three groups. Ten bars were indexed and connected with conventional torch soldering. A second group of ten castings was laser-welded. Ten solid, one-piece, cast bars served as controls. All thirty specimens were subjected to a four-point bending test with the use of a universal testing machine (Instron, model 4202, Instron Co., Canton, MA). Yield strengths were calculated from the load at yield point. The statistical evaluation revealed a significant difference between the laser-welded group and the soldered group. The laser-welded group had a statistically significant higher yield strength than the soldered group (p[less than]0.05). There was no statistically significant difference between the laser-welded group and the one-piece casting group (p[less than]0.05).
Description
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Thesis (M.Sc.D.)--Boston University, Henry M. Goldman School of Dental Medicine, 1996 (Prosthodontics).
Includes bibliographical references: (leaves 78-79).
Thesis (M.Sc.D.)--Boston University, Henry M. Goldman School of Dental Medicine, 1996 (Prosthodontics).
Includes bibliographical references: (leaves 78-79).
License
This work is protected by copyright. Downloading is restricted to the BU community. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.