Microleakage Assessment of CAD/CAM Crowns with Various Marginal Fit Parameters.
Abstract: Aim & Hypothesis This study aims to assess the amount of microleakage of CAD lithium disilicate crowns with different marginal fit settings and different finish line locations using E4D Dentist System. It is hypothesized that the amount of marginal microleakage for crowns fabricated at 0 mm and 0.25mm (factory default) marginal ramps will be higher than the crowns fabricated at 0.75mm ... read moremarginal ramp. Moreover, the amount of marginal microleakage will be higher in dentin (below CEJ) than enamel (above CEJ). Materials & Methods A total of 51 extracted premolars received full crown preparations, and samples were randomly divided into 3 groups. All teeth were scanned with the E4D system and the crowns were designed with different marginal ramp settings for each group. Crowns were milled out of IPS e.max blocks and cemented using Rely-X Ultimate. Samples were subjected to thermocycling for 5,000 cycles and immersed in 50% silver nitrate dye before being sectioned from mid buccal to mid-lingual. Microleakage was assessed under a stereomicroscope at x10 magnification. Results The difference in microleakage for the three groups was not statistically significant (p>0.05). Dentin margins exhibited significantly more microleakage than enamel margins. Conclusions The marginal ramp setting has no significant effect on the amount of microleakage for crowns fabricated with the E4D scanning and design system. In addition, placing the preparation finish line on enamel reduces the amount of microleakage compared to dentin.
Thesis (M.S.)--Tufts University, 2015.
Submitted to the Dept. of Other.
Advisor: Ali Muftu.
Committee: Matthew Finkelman, Hans-Peter Weber, and Ekaterini Antonellou.
Keyword: Dentistry.read less