NEW APPROACH TO AN AESTHETIC ALL CERAMIC CONCEPT FOR RESTORATION OF FRONTAL TEETH

Purpose. This study investigated the new aesthetic all ceramic concept with a double ferrule effect. Material and methods. 36 extracted human maxillary anterior teeth were endodontically treated and divided into 3 groups of 12. Group A, B, and C represented teeth prepared with a 0mm, 1mm, and 2mm new ferrule. As a material, we used Ø 1.4 mm Y-TZP VALL posts with retention rings in the coronary part of the post. The samples were cemented (Multilink Automix, Ivoclar), embedded in acrylic resin blocks (ProBase Polymer/Monomer, Ivoclar), and loaded at an angle of 45° degrees in an Instron Testing Machine 4301 (Instron Corp., USA) at a crosshead speed of 1mm/min until fracture. Fracture loads (N) and modes (repairable or catastrophic) were recorded. Two-way analysis of variance was used for statistical analysis with the level of significance seat p\u3c0.05. Failure patterns were analyzed in the optical microscope Stereo Discovery V.8 (Carl Zeiss, Germany). Results. The mean values (±SD) for fracture loads were measured (Newtons) for group A- 405,04N (±100.04); for Group B - 479.01N (±109.12) for Group E - 719.99N (±220.02). Failure patterns within those 1.4 mm Y-TZP posts groups revealed a noncatastrophic failure in group A = 100% for 0 mm, group B – 91.7% for 1mm, and 66.7% for 2mm new ferrule. Conclusion. With the limitations of this study, the teeth prepared without, and 1mm new ferrule demonstrated significantly lower failure loads than those with 2mm. The results showed that zirconia posts with new coronal rings and 2mm new ferrule which contribute to increasing the fracture resistance of the restored teeth, show significance higher fracture resistance. A significantly higher % of reparable fractures was determined in all the experimental groups