Abstract
Endocrowns are primarily recommended in a molar region with a standardized preparation design. The aim of the study was to evaluate the effect of different occlusal preparation depths, pulp chamber-radicular extension, and all-ceramic materials on the fracture resistance of premolar endocrowns. Ninety human premolar teeth were root canal treated, randomly divided into three main groups according to all-ceramic material used for fabrication as Lithium Disilicate (LD) ceramic, Polymer infiltrated ceramic (PIC) and High translucency zirconia (HTZ). They were further subdivided into three subgroups (n = 10) according to preparation design of 2 mm occlusal reduction, 4.5 mm occlusal reduction and 4.5 mm occlusal reduction with 2 mm radicular extension. The endocrowns from respective restorative materials were fabricated, surface conditioned, and cemented with self-adhesive resin cement. All samples were thermocycled for 5000 cycles and subjected to compressive static load at 45° angluation with the cross-head speed of 0.5 mm/minute until the fracture. The mean fracture resistance of LD ceramic at 2 mm, 4.5 mm thickness and radicular extension was 62.55 MPa, 45.80 MPa, 74.27 MPa respectively. The corresponding values for the PIC and HTZ ceramics were 26.30 MPa, 21.65 MPa, 25.66 Mpa and 23.47 MPa, 27.30 MPa, 37.29 MPa respectively. The LD ceramic and greater extension inside the pulp chamber had higher fracture resistance.
Highlights
Chronic apical periodontitis is the most prevalent diagnosed oral disease; several studies have highlighted the high prevalence of the root canal treated teeth in the population [1]
The Mean fracture resistance for Lithium Disilicate (LD) ceramic endocrowns at 2 mm occlusal thickness was 62.55 MPa, while at 4.5 mm thickness it was reduced to 45.80 MPa
The results of the present study showed the endocrowns with radicular extension had higher mean fracture resistance; the endocrowns fabricated from LD ceramic displayed higher mean fracture resistance
Summary
Chronic apical periodontitis is the most prevalent diagnosed oral disease; several studies have highlighted the high prevalence of the root canal treated teeth in the population [1]. Rehabilitation of endodontically treated teeth (ETT) with extensive coronal loss is a clinical challenge due to the higher risk of biomechanical failure [2]. The conventional approach is to re-build the coronal structural defect with an adhesive restore material along with the post and full veneer crown. The material and shape of the post influence the biomechanical behavior of the ETT teeth; besides its limited application of a post in the short, wide, and curved root canals. The endodontic post presents an additional risk of accidental root perforation and root fracture because of the incompatible modulus of elasticity with radicular dentin [3]. Bindl et al [5], and Lander et al [6]
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