Root form and canal morphology of maxillary first premolars of a Yemeni population.

Background: The purpose of this study was to investigate variations in the root canal systems of permanent maxillary first premolars in a Yemeni population using a clearing technique.
Methods: Two hundred fifty permanent maxillary first premolar teeth extracted from Yemeni individuals were collected. A small hole in the center of the occlusal surface of each tooth was prepared and pulp tissue was removed by immersion in 5.25% sodium hypochlorite. Teeth were stored in 5-10% nitric acid solution for 5-6 days. Next, teeth were rinsed, dried, and dehydrated using ascending concentrations of ethanol (70, 95, and 100%) successively for 12 h each. Waterproof black ink was injected into the dried dehydrated teeth. Stained teeth were then rendered clear by immersion in methyl salicylate solution (98%) until evaluation. Root canal morphology of each tooth was then examined.
Results: 54.8% of teeth were single-rooted, while 44.4% were double-rooted and only 0.8% had three separated roots. The most common canal system configuration was Vertucci type IV (55.6%). Eight specimens of the single-rooted premolars (3.2%) had new canal configurations that have not been recognized in previous published studies. Accessory canals and inter-canal communications were detected in a total of 52.8 and 34.4% of the specimens, respectively. The apical foramen was located centrally to the apex in 84.9% and apical deltas were found in 13.2% of the studied sample.
Conclusions: Yemeni permanent maxillary first premolars are mainly single-rooted and predominantly present Vertucci type IV canal morphology. The finding of additional canal configurations in this study is low but should be kept in mind when performing endodontic therapy for these teeth.