Purpose: to determine the prevalence of two canals and an isthmus in mandibular incisors at three levels, and to describe the canal anatomy in a simulated 20-degree surgical resection.
•N= 100 mandibular incisors
•100 mandibular incisors were randomly selected and stored in 10% formalin.
•teeth were then embedded in clear casting resin and apices of the teeth were resected at a 20-degree facial bevel at 1, 2, and 3 mm from the anatomical apex.
•teeth were then digitally imaged using a high-resolution camera at 50x magnification and measurements were made using imaging software.
•the presence of of an isthmus, number, shape, area, and dimensions of the canal at each level of resection were recorded.
Most highlighted Results:
•The prevalence of two canals was 2% at 1 mm, 0% at 2 mm, and 1% at 3 mm.
•Isthmus of tissue was present 20% of the time at 1 mm, 30% at 2 mm, and 55% at 3 mm.
• The more coronally the root-end resection was made, the more elongated the canal tended to become.
•In average, the canal was narrower in MD dimension than FL dimension at the 3 levels
mechanical cleaning may not be adequate to to debride the canal in the wider FL dimension and the areas of isthmus, so chemical cleaning is important. An isthmus opened during apical surgery needs to be included in the root-end preparation. care should be taken to avoid lateral perforation of the narrower MD.