Fig. 1From: CBCT evaluation of root canal morphology and anatomical relationship of root of maxillary second premolar to maxillary sinus in a western Chinese populationDistances from root tip to the maxillary sinus floor measured in the coronal section are divided into four types by the method of Shahbazian. a Distance larger than 0.5Â mm; b distance less than or equal to 0.5Â mm but larger than 0Â mm; c distance equal to 0Â mm, root tip attached to the sinus floor; d roots protruded into the sinus, distance recorded as negativeBack to article page