Accessory Canals Research Articles

Nouvelles observations sur Caprinula cedrorum Blanckenhorn

Abstract Describes the shell features of Caprinula cedrorum, concluding that the accessory canals and cavities in the outer margins of the valves represent the maximum of development and complication among the rudistid pelecypods.

CONGENITAL LESIONS OF THE NECK

The neck with its complex embryologic evolution is particularly subject to developmental anomalies. Among these may be mentioned branchial cysts and fistulas, cystic hygromas, submaxillary and submental inclusion cysts, dermoids, an accessory auditory canal, a lingual thyroid and an aberrant thyroid. Successful surgical assault of any congenital lesion consists of a complete reversal of the embryonic processes causing the condition in question. Obviously, in the subject being discussed at least a working knowledge of the embryologic anatomy of the neck is essential. The frequency of recurrences noted following surgical attack is evident testimony to the fact that a fundamental knowledge of the subject is not generally held. In the short space allotted, therefore, I shall sketch diagrammatically a rough working model of some of the embryology of the neck and its relationship to some of the common anomalies. EMBRYOLOGY Although noteworthy studies of the branchial apparatus have been made by

Do teeth have inclined planes?

Racial variations in root form and canal anatomy present endodontic challenges for clinicians. This study examined root canal morphology of three-rooted mandibular first molars by micro–computed tomography scans.A total of 122 extracted mandibular first molars were collected from a native Chinese population. After calculating the frequency of occurrence, 20 three-rooted (experimental group) and 25 two-rooted first molars (control group) were scanned and reconstructed three-dimensionally.The frequency of three-rooted mandibular first molars was 31.97% (39/122). The mean interorifice distances from the distolingual (DL) canal to the distobuccal (DB) and mesiolingual canal were 2.93 mm and 2.86 mm, respectively. The mesial root predominately contained a type 2-2 root canal, with an incidence of 65% in the experimental group and 64% in the control group. Type 1-1 canals were seen more frequently in the DL and DB roots of the three-rooted first molars as well as in the distal roots of the two-rooted first molars. The incidences were 100% (20/20), 95% (19/20), and 72% (18/25), respectively. Accessory and lateral canals rarely occurred in the extra DL roots. The incidence was only 10% (2/20). A furcation canal extending from the floor to the furcation region was not observed.Three-rooted mandibular first molars commonly have 4 separate canals with high incidences of accessory canals in the mesial and DB root. The geometric data of pulp floors are useful for locating the extra DL canal.