introduction: the aim of this in vitro study was to compare the effect of hand and rotary instruments on fracture strength of tooth roots. materials & methods: thirty two teeth were randomly divided into two experimental groups of 15 each and one negative control group with two samples. in group 1, step-back technique with conventional stainless steel k-files was used, and in group 2, instrumen...

introduction: preparation techniques and instruments produce and push debris out of canals. this can induce inflammation within the periapical area. therefore, instrumentation that causes less extrusion of debris is more desirable. the purpose of this in vitro study was to evaluate the quantity of debris extruded from the apical foramen during root canal preparation by using one hand, and two r...

various and complex human activities in geographical contexts need proper ground if at most efficiency is to be achieved. land preparation regulates the relationship between human, space, and human activities. land preparation has various dimensions related to value system, political, scientific, artistic, and defense-security aspects. one of the most important dimensions of land preparation is...

one of the major challenges in mega cities is the degree of the preparedness of organizations, institutions and people in facing with critical conditions and their immediate reaction according to pre-defined instructions. identification of priorities and acting accordingly is an undeniable factor in urban crisis management. the purpose of this research was to identify the priorities of prepared...

many modern analytical methods deal with the trace-level determination of compounds of interest in highly complex environmental samples by means of chromatographic techniques. the introduction of a “clean” sample into an analytical instrument can make analyses easier and prolongs the equipment life. the use of solid-phase extraction (spe) has grown and is a fertile technique of sample preparati...

objectives: the aim of this study was to compare the permeability of dentin after using diamond bur and er:yag laser. materials and methods: seventy-two recently extracted, intact, and restoration-free human permanent molars were used in this study. the samples were randomly divided into three groups of 24 each and class i cavities were prepared as follows. group 1: high speed diamond bur with ...

in this article we review the application and procedures involved in scanning electron microscope (sem) to observe biological and live tissues through using sem at high resolution. we discuss practical methods for optimizing tissue preservation to achieve the two principal goals of biological specimen preparation: (a) preserving biological structures as close to their living configuration as po...

objective: repair of an indirect restoration is usually preferred over its replacement. this study aimed to evaluate the effect of silane in different surface preparation techniques on the bond strength of direct to indirect composite resin.   methods: for this in vitro experimental study, 48 indirect composite cubes were fabricated, divided into 4 groups of 12 and subjected to the following pr...

purpose the aim of this study was to compare the levels of serum immunoglobulin (iga, igm, igg), testosterone and cortisol in semi-endurance elite runners during general preparation and competition phase of training. methods thirteen semi-endurance elite male runners with an average age of 18.92±1.7 years volunteered to take part in this study. the runners participated in the selected training ...