PubMed · 6423551
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
P R Dow. 1984. EDTA - time for re-evaluation?. https://doi.org/10.1111/j.1365-2591.1984.tb00371.x
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
The mesiobuccal roots of 50 randomly selected maxillary first molars were examined to assess the incidence and position of the canal isthmus. Transverse serial sections of the apical 6 mm of each root were prepared in 1-mm increments. The apical side of each section was stained with methylene blue dye, viewed with a surgical operating microscope, and videotaped. Forty percent of the roots had one canal, whereas 60% had two canals. None of the sections had more than two main canals. The incidence of an isthmus was highest in the apical 3- to 5-mm levels. In teeth that had two canals, the 4-mm sections contained a complete or partial isthmus 100% of the time. The concept of a partial isthmus was presented. Failure to deal with the isthmus may explain why some posterior teeth do not heal completely following endodontic surgery.
The degree and configuration of canal curvature was studied in the mesial roots of 100 randomly selected mandibular first and second molars. The teeth were radiographed in buccolingual (clinical) and mesiodistal (proximal) directions with #8 K files in place. One hundred percent of the specimens demonstrated curvature in both views. No correlation in degree of curvature was found to exist between the clinical and proximal views. Secondary curvature, in a direction opposite to that of the principle curve, was seen more frequently in the proximal view. In the proximal view, canals exhibited greater mean curvature than in the clinical view 38% of the time. Weine type II morphology (two canals, one foramen) demonstrated the greatest range in canal curvature when viewed from the proximal. Coronal flaring with Canal Master rotary instruments to a level just coronal to the curve significantly reduced the severity of curvatures in both views for most cases.
In this study, 100 mandibular central and lateral incisors were used to determine the number of root canals and their types, the ramifications of the root canal, the location of apical foramina, and the frequency of apical deltas. The teeth were immersed in India ink, decalcified, and cleared. The examination of root canal systems of the teeth was based on Vertucci's classification. Two more root canal types which are not defined in that classification have also been determined and grouped as new types.