PubMed · 4514821
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
J G de Boer. 1973. [Radix entomolaris].. https://pubmed.ncbi.nlm.nih.gov/4514821/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
The purpose of this study was to compare the ability of radiographic and electronic methods to determine reliably the location of the apical constriction. The working length of root canals in human cadaver teeth was determined by positioning an endodontic file at the apical termination point as indicated by an apex locator. These same teeth were radiographed at various angles with the file in place. The radiographs were evaluated by five examiners to determine a radiographic termination point for each canal. Teeth were extracted and examined histologically to determine the ideal termination point. The deviations of the two experimental termination points from the ideal termination point were compared. The mean of the absolute value of the deviations from the apical constriction for the apex locator was significantly less (p < 0.05) than that for the radiographic method. Thus, the method using the apex locator was slightly more reliable.
The purpose of this study was to investigate the pattern of bacterial invasion of dentinal tubules at different regions in human roots. Specimens were obtained from single-rooted teeth that had their root canals prepared in a standard manner. Roots were then sectioned longitudinally through the canals and the resulting specimens chemically treated to remove the smear layers. Specimens were immersed in a suspension of Streptococcus gordonii for 3 weeks and then prepared for histological analysis. Sections from the cervical, midroot, and apical areas were examined. The pattern of bacterial infection of the cervical and midroot areas was similar, characterized as a heavy infection with bacteria penetrating as deep as 200 microns. Invasion of the apical dentin was significantly different, with a mild infection and maximum penetration of 60 microns.
Recently, root canal preparation using Nd:YAG laser has been introduced. Laser interaction with matter may generate cavitation and subsequent pressure waves. This study characterized the pressure waves induced in root canals by either Nd: YAG laser, sonically vibrated files, or ultrasonically vibrated files. The root canals of 14 single-rooted teeth were prepared conventionally and filled with water. In 12 teeth, a pulsed Nd:YAG laser was activated in the canal using optical fibers of various diameters and various power settings. In the remaining two teeth, either a sonic or ultrasonic file was activated. The pressure waves induced in the canals were detected by a piezoelectric transducer. The results were analyzed using correlation coefficient and coefficient of variation. Laser irradiation resulted in pressure waves with amplitudes varying from 35.78 to 79.26 mV, being positively correlated with the laser power density (R2 = 0.870). Sonic and ultrasonic vibrations resulted in pressure waves with mean amplitudes of 60.51 mV and 7.02 mV, respectively. It was concluded that Nd:YAG laser irradiation induced pressure waves, with different characteristics from waves induced by freely vibrating sonic and ultrasonic endodontic instruments when applied to water-filled root canals.