IN VITRO COMPARISON OF VERTICAL MARGINAL GAPSOF CEREC DESIGN METAL FRAMEWORKAND CONVENTIONAL CAST METAL FRAMEWORK FOR A 3 UNIT FPD

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Objective. The purpose of this study is to evaluate if there is a significant difference in marginal gap of metal frameworks for a 3 unit FPD fabricated by two different techniques: the lost-wax and a CAD/CAM. Background. The accuracy of fit of dental castings is imperative for the success of any prosthodontic treatment. Smaller gaps produce less gingival irritation and decrease cement washout improving the clinical outcome and longevity of the restoration. Various methods and procedures have been advocated to improve the accuracy of fixed partial denture (FPD) fabrication. Methods. Twenty typodonts were used as patient analogues. Each typodont had prepared teeth on the first right lower premolar #28 and on the first right lower molar #30 for 3-unit PFM-FPD restorations (28-X-30). Two groups (Groups A and B) were made with 10 samples in each group. For the first group (Group A), impressions of the prepared teeth were made with light and heavy body PVS. They were poured in stone to produce casts where 3-unit frameworks were waxed up. For the second group (Group B) preparations were scanned using CAD/CAM CEREC InLab in order to create a digital impression that was used to fabricate the 3-unit acrylic framework for a PFM FPD by milling the VITA CAD-Waxx for in Lab using the CAD/CAM Cerec milling machine. Each pattern from groups A and B were placed in a casting ring, invested and cast with a noble metal alloy to produce all metal frameworks. Then frameworks were cemented into each typodont using dual curing luting composite cement and using a jig they were sectioned in specific points of reference to measure vertical marginal gaps between each tooth preparation and metal framework using a zoom stereomicroscope. Results. To be determined. Conclusion. To be determined. Grants. This study was fully funded by a grant from the Health Professions Division Research Fund.