OBJECTIVES The aim of this study was to compare the fracture load of veneered anterior zirconia crowns using normal and Weibull distribution of complete and censored data. METHODS Standardized zirconia frameworks for maxillary canines were milled using a CAD/CAM system and randomly divided into 3 groups (N=90, n=30 per group). They were veneered with three veneering ceramics, namely GC Initia...

background and aim: the present study aimed at determination of the fatigue resistance and failure mode of cusp-replacing onlays in endodontically treated premolars using indirect composite resin restorations. materials and method: in this experimental study, 84 human premolars were randomly divided into 7 groups of 12. these groups were prepared as follows: intact teeth used in group1 as contr...

statement of the problem: one disadvantage of cement-retained crowns is the lack of predictable irretrievability. this problem can be overcome through designing a screw access hole in the metal substructure of cement-retained restoration and using porcelain stain to define this area. purpose: this study aimed to evaluate the influence of existence of screw access hole on porcelain fracture resi...

Objective: Introduction of fiber-reinforced composites (FRC) greatly enhanced the restoration of fractured anterior teeth. The purpose of this study was to assess the effect of fiber reinforcement on fracture resistance of incisal edge composite restorations of variable thicknesses. Methods: Forty extracted sound human maxillary incisors were divided into four groups of 10. Incisal reduction wa...

An observed minimum in the critical crack initiation load at Poisson’s ratio (ν) of 0.21–0.22 in Na2O–TiO2–SiO2 glasses was investigated. Vickers indentation was used to examine hardness and average cracking length, fracture toughness was measured through the single-edge pre-cracked beam method, and volumes of densification and shear flow around indents were measured using atomic force microsco...

Residual stress present in coupons used for fracture testing will influence the experimental determination of fracture toughness. Triaxial residual stress (e.g., due to welding) can alter both the driving force for fracture and the crack-tip constraint at a specified load, so that the apparent toughness of a coupon depends on the residual stress present. In this paper, we employ a micromechanic...

An investigation into the mixed mode fracture of steel fiber reinforced concrete (SFRC)beams with one percent volume fraction of steel fiber is presented. A series of notched beams withdifferent notch depths and locations are tested under three-point bending. The test results for apparentfracture toughness, crack trajectories, and fracture energy are presented. The crack paths for SFRCand plain...

Fracture healing requires two major pre-requisites; sufficient blood supply and mechanical stability [1-2]. Optimum mechanical conditions for fracture healing remain unknown, but micro-movements of the fracture fragments are significant to a developing healing callus [2-3]. This study uses Finite Element analysis to evaluate an idealized neck fracture callus, for single, and two lag screw intra...

OBJECTIVE The aim of this study was to compare the fracture strength of roots instrumented with three different single file rotary systems in curved mesial root canals of maxillary molars. MATERIALS AND METHODS Curvatures of 25°-35° on mesial roots of 60 maxillary molar teeth were sectioned below the cementoenamel junction to obtain roots 11 mm in length. The roots were balanced with respect ...