Texturized Anatomies

3D models of root canals textured with computer graphics to resemble pulp tissue

Mandibular Incisor

With Prof. Martin Filpe

From the University of Maimonides

Argentina

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Why does mandibular incisor fail?

Usually, teeth with single roots present single canals as in mandibular and maxillary anterior teeth. However, particular tooth types, such as mandibular premolars and incisors, are recognized as exhibiting a distinct range of variations in the morphology of their root canal system. In mandibular incisors, often a dentinal bridge is present in the pulp chamber dividing the root into two canals. The two canals usually join and exit through a single apical foramen, but they may persist as two separate canals. On occasion one canal branches into two canals, which subsequently rejoin into a single canal before reaching the apex. The incidence of two canals in mandibular incisors has been reported to be as low as 0.3% and as high as 45.3%. The wide range of variation reported in the literature regarding the prevalence of a second canal in mandibular incisors has been mostly related to methodological and racial differences.

(Very soon on the Journal of Endodontics)

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Mandibular Incisors

Narrow and  flat in the  labial-lingual  dimension, the mandibular incisors are the smallest human adult  teeth.  Visible radiographically  from  only one  plane,  they  often  appear more accessible than they really  are. The  narrow lingual crown offers a  limited area for  access. Smaller  fissure burs and no. 2  round burs  cause  less  mutilation of coronal  dentition. The access cavity  should be  ovoid,  with  attention given to a lingual approach. Frequently the mandibular  incisors have two  canals. One study  reported  that  41.4% of mandibular incisors studied had two separate  canals; of  these,  only  1.3% had two  separate foramina. The  clinician should  search for the  second  canal immediately upon  completing the access  cavity. Endodontic  failures in mandibular incisors usually  arise from  uncleaned canals, most commonly  toward the  lingual.  Access may be extended incisally when indicated to permit maximum  labiallingual  freedom.  Although labial  perforations are  common,  they may be avoided if the clinician  remembers  that it is nearly  impossible to perforate in a  lingual  direction because of  the bur shank's contacting the incisal edge. The ribbon-shaped canal is common enough to be considered normal and  demands special  attention in cleaning and shaping. Ribbon-shaped  canals in narrow  hourglass  cross-sectional anatomy invite  lateral perforation  by endodontic  files and Gates-Glidden  drills.  Minimal  flaring and  dowel space  preparation are indicated to  ensure  against ripping  through  proximal root walls. Apical curvatures and accessory canals are common in mandibular incisors (Burns RC, Buchanan LS. Tooth Morphology and Access Openings. Part One: The Art of Endodontics in Pathway of Pulp, 6th Ed. p. 152).

 

 

Keywords: micro-computed tomography, micro-ct, marco versiani, micro-computer tomography, high resolution x-ray tomography, dental anatomy, root canal anatomy