IN VITRO EVALUATION OF THE MARGINAL INTEGRITY OF MONOLITHIC CERAMIC CROWNS UTILIZING DIFFERENT MACHINABLE BLOCKS FABRICATED FOR MINIMALLY INVASIVE VERTICAL PREPARATION DESIGNS

Abstract

Purpose: This study aimed to evaluate the marginal adaptation of monolithic ceramic crowns with minimally invasive vertical preparation design utilizing different machinable blocks. Materials and method: Stainless steel die was designed to simulate all ceramic crown preparation with 0.1mm featheredge margin. A total of 50 monolithic crowns were constructed from five different tested ceramic materials; 10 crowns from each material: Group EX for lithium disilicate ceramic (IPS. emax), group VE for polymer infiltrated ceramic (Vita Enamic), group CD for zirconia-reinforced lithium silicate ceramic (glazed Celtra Duo), group TZ for translucent zirconia (inCoris TZI) and group HTZ for high translucent zirconia (Ceramill zolid zirconia). After surface treatments, adhesive cementation and thermocycling, stereomicroscope with a digital camera and image analysis software were used to measure the vertical gaps between the cervical margin of the crown and the outer end of the finish line. The mean vertical gap for each crown was then calculated. Results: High translucent zirconia crowns (group HTZ) showed the lowest mean marginal gap value (29.04 ±7.77μm) with statistically significant difference than all the other tested materials. While e.max crowns EX showed the highest mean marginal gap value (95.37 ±13.84μm) which was statistically significant from all the other tested groups. Conclusion: High translucent zirconia crowns showed superior marginal adaptation compared to all other tested materials, while lithium disilicate crowns showed the least accuracy. For the all tested materials, the marginal vertical gap readings recorded in this study were within the limits of clinically acceptable standards.