Evaluation of the Accuracy of Solid Implant Casts |
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| Authors: | Alvin G Wee BDS MS Robert L Schneider DDS MS Steven A Aquilino DDS MS Thomas L Huff DDS MS Terry J Lindquist DDS MS Derrick L Williamson DDS MS |
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| Institution: | Assistant Professor, Section of Restorative Dentistry, Prosthodontics and Endodontics, The Ohio State University, Columbus, OH.;Associate Professor, Department of Prosthodontics and Clinical Director, Oral and Maxillofacial Implant Center, The University of Iowa, College of Dentistry, Iowa City, IA.;Professor and Director of Graduate Prosthodontics, Department of Prosthodontics, The University of Iowa, College of Dentistry, Iowa City, IA.;Associate Professor and Head, Department of Prosthodontics, University of Texas at Houston, Houston, TX.;Assistant Professor, Department of Prosthodontics, The University of Iowa, College of Dentistry, Iowa City, IA. |
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| Abstract: | Purpose Materials used to fabricate the most dimensionally accurate implant casts have not been identified experimentally. The purpose of this investigation was to examine the dimensional accuracy of implant casts fabricated with different materials. Measurements of linear horizontal dimensional change and strain produced on a master framework were evaluated and correlated. Materials and Methods A master framework was fabricated to fit an aluminum five-implant model. Forty polyether implant impressions of the aluminum model were randomly grouped and poured in either Vel-mix, Die Keen, Resin Rock, or Low Fusing Alloy. A digital veneer caliper was used to measure linear distance between the most distal abutments on each of the experimental implant casts and the master model. In addition, strain values were recorded from strain gauges bonded in the mesiodistal axis of the framework, which was secured by prosthetic retaining screws torqued to 10 Ncm. Results A one-way ANOVA showed a significant difference among the four die materials in dimensional change of the experimental casts (p= .0001). A post-hoc Duncan's multiple-range test (p < .05) showed that casts fabricated with Low Fusing Alloy had the least linear dimensional change from the master cast, but the material exhibited the greatest dimensional variability. A MANOVA (Wilks' Lambda) showed significant differences in strain on the framework based upon die material (p= .015). A post-hoc Duncan's multiple-range test (p < .05) showed that Resin Rock casts induced significantly less strain on the framework than the other materials. Negligible correlation was found between the linear horizontal dimensional change and the total absolute strain on the framework. Conclusion Experimental implant casts made of Resin Rock minimized strain on the master framework and decreased the amount of framework distortion on casts of this material. Low Fusing Alloy yielded accurate casts, but highly variable linear dimensional changes in the horizontal dimension may preclude its clinical benefit. |
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| Keywords: | dental implants dental materials dental gypsum dental casts dental alloys |
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