INFLUENCE OF FINISH LINE DESIGN ON THE VERTICAL MARGINAL DISCREPANCY OF ENAMIC HYBRID CERAMIC: IN VITRO STUDY

Abstract

Aim of the study: The aim of this study was to evaluate the effect of finish line design (chamfer and shoulder) on the vertical marginal gap distance, and fracture resistance of Hybrid ceramic (Vita Enamic, VITA Zahnfabrik, Bad Sackingen, Germany). Materials and Methods: Two stainless steel dies were machine milled to simulate a tooth preparation for a ceramic crown of a mandibular second molar with two finish line configurations 1mm chamfer and 1 mm shoulder. Each die was 6-mm in height, 8-mm in cervical diameter, 6mm in occlusal diameter and had a total occlusal convergence of 16o. Digitalization of both dies and milling of hybrid restorations was made using CAD-CAM technology. Sixteen full coverage hybrid ceramic crowns were constructed from milled Vita Enamic hybrid ceramic blocks. The samples were divided into two equal groups’ eight samples for each finish line tested.-Group Ac: eight samples (n=8) with Chamfer finish line.Group Bs: eight samples (n=8) with Shoulder finish line. All restorations were positioned onto a digital-microscope, magnification 50 X, and the images were captured and transferred to a IBM personal computer equipped with the Image-tool software to measure the vertical marginal gap distance. Results: The results showed a statistically significant difference between the two groups (Ac, Bs) where the mean values were (35.44μm and 48.36μm) respectively at p=0.002. Conclusions: the vertical marginal gap values of both finish line designs are within the clinically accepted range