Marginal Fit of Monolithic Zircon Crowns Fabricated by Different Digital Impression Techniques

Purpose: The aim of this study was to assess the precision fit of different techniques of digital impression for the prepared abutment, its conventional impression, and the stone die by evaluating marginal fit of monolithic zirconium crowns .
Materials and Methods. A standardized Computer Numerical Control machine (CNC) will be used to reduce a standred stainless steel master die with nearly similar dimensions, an occluso-gingival height of 6 mm, a taper of 6° and 1 mm shoulder circumferentially. The overall diameter of the specimen at the base is 8-8.5 mm. Poly vinylesiloxan impression was taken and poured with type IV stone to obtain the stone die .The master die (prepared abutment), the impression and the stone die were digitally scanned for fabrication of monolithic zircon crowns. Three groups of zirconium crowns 10 crowns per each as follow: First group (Gp1) :standard stainless steel master die. Second group (Gp2): Poly vinylesiloxan impression of the master die ;Third group (Gp3): Stone die .The master dies and the impressions were sprayed before scanning while the stone dies were not.The three groups were scanned , the zircon crowns were designed with:Prettau® Zirkonzahn®,sotware and milled from Zirconium block . All the milled crowns seated on the master die . A specially designed device was machined in order to aid in specimen holding during gap evaluation. A digital image analysis system was used to measure and qualitatively evaluate the gap width. Inside the Image J programming, all points of confinement, sizes, outlines and estimated parameters are communicated in pixels. At that point morphometric estimations were improved the situation each shot 4 equidistant milestones along the minimal perimeter for each surface of the example (Mesial, buccal, distal, and lingual). At that point the information acquired were gathered, arranged and afterward subjected to measurable examination.
Results: One way ANOVA test was utilized to look at between the minorgap of the three gatherings. Where P value equal 0.09 , it was viewed as that there is no-huge difference between them. While there is no significance, still the higher negligible gap was recognized in the crown manufactured from traditional impression (Gp II) and the lower gap in the crown created from the stone die on examining (Gp III).
Conclusion: Based on the aftereffects of the present research, it was inferred that advanced checking for monolithic zircon crowns acquired utilizing distinctive digitalscanning strategies gave a lower minimal gap or most extreme fit an incentive for three estimations in stone die