statement of problem: microorganisms are essential for the development of periradicular diseases and are one of the major causative factors associated with endodontic treatment failures. different instruments and preparation techniques have been developed in endodontics to eliminate or reduce intracanal bacteria. purpose: the aim of this study was to compare the amount of remaining e. faecalis ...

ultrasonic machining (usm) is a mechanical material removal process used to erode holes and cavities in hard or brittle work pieces by using shaped tools, high-frequency and an abrasive slurry. this paper addresses the concept and development of an expert system (es) for hard and brittle material, such as glass, quartz, diamond, carbides, semi conducting materials, ceramic and graphite which ca...

background and aims. the superiority of rotary systems has been reported in several clinical studies on permanent teeth. this study consisted of radiographic assessment and chair time of rotary instruments in the pulpectomy of primary second molar teeth. materials and methods. in this randomized controlled clinical study, 46 children, 3-6 years of age, were selected. the patients were divided r...

introduction: this study aimed to perform a rigorous sample standardization and also evaluate the preparation of mesiobuccal (mb) root canals of maxillary molars with severe curvatures using two single-file engine-driven systems (waveone with reciprocating motion and oneshape with rotary movement), using micro-computed tomography (micro-ct). methods and materials: ten mb roots with single canal...

introduction : removal of root filling materials is one of the key steps in success of root canal retreatment. the purpose of this study was to evaluate the efficacy of h-file and protaper with or without chloroform in the removal of gutta-percha during retreatment of mandibular premolars. materials and methods: sixty mandibular premolars with one canal, and curvatures less than 30 degrees were...

introduction: root fracture is not an instant phenomenon but a result of gradual development of tiny craze lines in tooth structure. recent studies have shown that canal instrumentation has the potential to cause dentinal cracks. the purpose of this study was to evaluate and compare the formation of dentinal cracks caused by protaper rotary system to hand instrumentation. materials and methods:...

The angular error of indexing table on machine tool is measured using new developed measuring device. The measuring techniques, which have been reviewed in this paper, are currently available in manufacturing engineering to calibrate the angle measurement. The new developed measuring device using 6 points kinematic concept and employing ball and vee grooves is used to calibrate angle errors of ...

The change from steerable motor to rotary steerable system has been both technically and commercially successful in Lybia. Through these case histories the paper will demonstrate benefits resulting from the use of rotary steerable systems that have led to a step change in overall drilling performance in the Middle East. This paper describes the successful introduction and application of a rotar...

OBJECTIVES The aim of this in vitro study was to compare the efficacy of two retreatment rotary systems in the removal of Gutta-percha (GP) and sealer from the root canal walls with or without solvent. MATERIALS AND METHODS Forty-eight extracted human mandibular first premolars were prepared and obturated with GP and AH Plus sealer. Samples were then randomly divided into four groups. Group I...