Résumé
The objective was to determine the frequency of second canal in extracted maxillary second premolars. This was an in vitro study conducted at the Department of Operative Dentistry, Liaquat University of Medical and Health Sciences, Jamshoro from October 2011 to March 2012. This study included two hundred extracted human maxillary second premolars. The pulp chambers were accessed with round bur in a high speed air turbine, and they were irrigated with 2.5% sodium hypochlorite solution for 12 hours to dissolve the pulp tissues, then rinsed under running tap water for 2 hours and dried overnight. The dye was introduced coronally and flooded throughout the pulp space by vacuum suction apically. Teeth were then decalcified in 5% nitric acid solution for five days. Eventually teeth were made clear by dipping in methyl salicylate and examined under operating microscope under 7.5 x magnification for the frequency of second canal. Results showed that the frequency of second canal of the maxillary second premolars is 37% [74/200]. Chi-square test was used to evaluate the results. It was concluded that dentists must always look for the second canal during endodontic treatment of the maxillary second premolars