الفهرس 
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Abstract
Morphological variations in root canal anatomy due to ethnicity have been reported in many studies; therefore, identifying the root canal anatomy of maxillary first molar of different ethnic populations is required for successful endodontic treatment.
The aim of our study was evaluated the root canal morphology of maxillary first molars In Egyptian population using two different methods. Four hundred and fifty teeth were collected for this study. The number of roots was examined clinically. Then the samples were scanned using a Next Generation i-CAT scanner cbct (Imaging Sciences International, Inc, Hatfield, USA). At a constant slice thickness of 125 mm/slice, scanning time were 26.9 sec. Root canal System configurations were classified according to Vertucci classification using Invivo Dental software (version 5.3; Anatomage, San Jose, CA, USA) and the root canal curvature of MB, DB and P roots were measured using Schneider technique. Then an endodontic access cavity was prepared in each tooth. The teeth were consecutively immersed in 5% nitric acid for 6 days, and then dehydrated in ascending concentrations of alcohol for 12 hours. To have transparent specimens they were immersed inside methyl salicylate solution. Finally, India ink was coronally injected into the pulp chambers with a plastic disposable syringe with a 23 gauge needle. The fine details, such as lateral canals inter canal communications and apical deltas were examined.
The most common root morphology in maxillary first was three separate roots. In the present study maximum variations in canal anatomy were discovered in the MB canal of maxillary first molar, the most prevalent canal systems in the MB roots were Vertucci Type II (38.7%) followed by Type IV (24.9%), then Type I (20.7%) followed by Type V (7.8%) and then Type VI (4.4%). Also the number of lateral canals (8.6%), inter-canal communications (18%) and apical delta (21%) were found commonly in the MB root. The DB and P roots showed predominantly type I canal morphology.