Purpose: to evaluate the relationship between the root apices of the lower first and second molars to the upper border of the mandibular canal & to establish the location in the buccolingual & vertical planes of the canal relative to the apices of these teeth.
N= 46 dry mandibles
•All mandibles were of adults, included fully erupted molars & had a uniform plane of occlusion.
•Half-mandible was divided into two groups;
(1) second premolar and first molar,
(2) second and third molar
•All mandibles were examined radiographically with two periapical radiographs for each.
•Measurements were performed twice once with a magnifying glass ruler and calipers and a second time with a viewer without magnification.
Most highlighted Results:
n = 42 dry mandibles
•The shortest distance measured between the root ends of the lower molars and the upper border of the mandibular canal is from the distal root end of the second molar in both sides. Distance increases gradually as we go mesially.
•Symmetry was found in all cases.
•The mandibular canal in the posterior area showed a greater tendency to be in the plane of or superior to the root apices than in the more mesial area.
Traumatic dental procedures in the lower jaw such as over extension of instruments or materials in root canal therapy or surgical procedure may result in damage to the neurovascular bundle . Furthermore, when root apices are seen to be in close contact to the upper border of the mandibular canal, two radiographs should be taken with a difference of –20 degree.