Background. Fracture load of implant-supported restorations is an important factor in clinical success. This study evaluated the effect of two techniques for screw access hole preparation on the fracture load of cement-screw-retained implant-supported zirconia-based crowns. Methods. Thirty similar cement-screw-retained implant-supported zirconia-based maxillary central incisor crowns were evalu...

PURPOSE To investigate the effect of reducing tooth preparation and ceramic thickness on fracture resistance of lithium disilicate crowns. MATERIALS AND METHODS Specimen preparation included a standard complete crown preparation of a typodont mandibular left first molar with an occlusal reduction of 2 mm, proximal/axial wall reduction of 1.5 mm, and 1.0 mm deep chamfer (Group A). Another typo...

This letter describes a newly discovered phenomenon: ductile fracture in cementitious materials. The brittle nature of materials such as concrete and ceramics has prompted the development of various approaches to enhance their fracture toughness. Fibre reinforcement has been the common focus in the toughening of the brittle materials. Two types of fracture have been observed to date in cementit...

objectives : the purpose of this in vitro study was to compare the marginal adaptation and fracture resistance of a zirconia-based all-ceramic restoration with two preparation designs. materials and methods: twenty-four mandibular premolars were randomly divided into two groups (n=12); the conventional group received a peripheral shoulder preparation and the modified group received a buccal sho...

OBJECTIVES The purpose of the present study was to analyze the relationship between fracture load of monolithic zirconia crowns and axial/occlusal thickness and to evaluate the fracture resistance of monolithic zirconia crowns with reduced thickness in comparison with that of monolithic lithium disilicate crowns with regular thickness. MATERIALS AND METHODS Monolithic zirconia crowns (Lava Pl...

PURPOSE This study evaluated the fracture load of customized zirconia abutments with titanium insert according to preparation depths, with or without 5-year artificial aging. MATERIALS AND METHODS Thirty-six identical lithium disilicate crowns (IPS e.max press) were fabricated to replace a maxillary right central incisor and cemented to the customized zirconia abutment with titanium insert on...

statement of problem: the restoration of the teeth should have enough ability to withstand masticator forces while preserving as much tooth structure as possible. purpose: the purpose of this study was to compare the effects of light-heat cured composite with light cured composite restorations on fracture resistance of the restored teeth. materials and methods: forty healthy maxillary premolar ...

this study focused on the optimization of al—mg to cuzn34 friction stir lap welding (fslw) process for optimal combination of rotational and traverse speeds in order to yield favorable fracture load using grey relational analysis (gra). first, the degree of freedom was calculated for the system. then, the experiments based on the target values and number of considered levels, corresponding orth...

The purpose of the present study is to examine the relationship between the supportive designs of proximal region of zirconia framework on the fracture load. The zirconia frameworks with four different supportive designs on the proximal region were fabricated and classified with their radiuses of curvature (R): R=0.5 mm, R=1.0 mm, R=1.5 mm, and R=2.0 mm. The zirconia frameworks were conditioned...

The fracture and crack growth of mechanical structures is a usual phenomenon which is due to the application of tensile, cyclic loading or thermal stresses on the structure. So introducing of methods to prevent the crack growth is useful. Afterward, one of the repairing methods of crack growth, consisting to make a hole in the crack tip to elimi-nate the sharp corners, was explained. This metho...