Abstract :
This study aimed to compare fracture resistance on endodontically treated premolars restored with endocrowns and conventional crowns reinforced with and without fiber posts when subjected to pressure forces. 30 intact premolars were extracted for orthodontic reasons. All teeth had nearly identical dimensions, endodontically treated and divided into three equal groups (10 each). Then all premolar crowns were cut at 2 mm above the CEJ. Group A were restored by glass ceramic reinforced with lithium disilicate (LDS) Endocrowns. Group B were restored by LDS conventional crowns reinforced with fiber posts. Group C were restored by LDS conventional crowns reinforced with a composite build-up without posts. All restorations were cemented by dual cure resin cement and then subjected to pressure test by using a general mechanical testing machine. Each sample was loaded until fracture. The data were recorded by Newton (N). Samples failure modes were examined by stereoscope and radiography. Then the data were statistically analyzed. One-way ANOVA then Bonferroni (Sidak) test were used to determine and reveal any significant differences in fracture strength means between the groups. Chi Square test was also used to analyze the relationship between fracture strength means and failure modes. One-way ANOVA test revealed statistically significant differences between fracture strength means of the studied groups (p> 0.05), and Bonferroni (Sidak) test revealed significant differences between group A (914.2) N and B (734.2) N and between A and C (792.3) N, while there was no statistically significant difference between group B and C. Irreparable fractures were mostly seen in group A due to higher fracture strength means. Endocrowns revealed the highest resistance fracture mean, followed by the classical crowns groups. Endocrowns mostly caused unfavorable failures. Crowns reinforced composite with no posts (group C) showed a preferred behavior, so it is a promising method because of its less invasive approach.
