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...

screw-retained implant restorations have an advantage of predictable retention as well as retrievability, and obviate the risk of excessive sub-gingival cement commonly associated with cement retained implant restorations. screw-retained restorations generally have screw access holes, which can compromise esthetics and weaken the porcelain around the holes. the purpose of this study is to descr...

The intralaminar screw construct has been recently introduced in C6-C7 fixation. The aim of the study is to compare the stability afforded by three different C7 posterior fixation techniques using a three-dimensional finite element model of a C6-C7 cervical spine motion segment. Finite element models representing three different cervical anchor types (C7 intralaminar screw, C7 lateral mass scre...

To compare the mechanical effectiveness of a new conical screw design with a conventional cylindrical screw design, the screw insertion time, torque, and pull-out strength of single-pedicle screw and triangulated-pedicle screw constructs of each type of screw were compared in human cadaveric vertebral bodies. The time required to insert the conical screws was less than that required for cylindr...

STUDY DESIGN Pedicle screw strength or load to failure was biomechanically evaluated, and the geometric characteristics of pedicle screw instrumentation systems were compared. OBJECTIVES To compare the features of pedicle screw systems, and to demonstrate the failure point of the polyaxial pedicle screw head. SUMMARY OF BACKGROUND DATA Many pedicle screw instrumentation systems are currentl...

The aim of this study was to compare the interfragmentary compression generated across a simulated femoral fracture model by a conventional 4.5 mm AO/ASIF cortical lag screw with a differentially pitched cortical compression screw. A 45-degree osteotomy was made in a whole bone composite femoral shaft, this was internally fixed with either a conventional 4.5 mm AO/ASIF cortical lag screw or the...

BACKGROUND Efforts to select the appropriate number of implants in adolescent idiopathic scoliosis (AIS) instrumentation are hampered by a lack of biomechanical studies. The objective was to biomechanically evaluate screw density at different regions in the curve for AIS correction to test the hypothesis that alternative screw patterns do not compromise anticipated correction in AIS when using ...