Morphology Of Physiological Foramen Of Mandibular Premolars

Objective: To investigate the morphology of physiological foramen of mandibular premolars.Materials and methods: A total of 81 extracted human mandibular premolars from a Chinese population. A computer-aided stereomicroscope with 50 X magnification was used in this study. The root morphology of the apical areas was examined at 50 X magnification. Each root was directly illuminated and oriented until the physiological foramen was located in the middle of and parallel to the objective lens. The tooth number and type, root type, physiological foramen location and shape. The diameter of the physiological foramen was measured with the software length measuring mode. The foramen was considered accessory when its diameter was narrower than 0.10mm. A physiological foramen with roundness equal to 1 was defined to have a non-round instead of a round shape. Results: There were 12 teeth having two or more than two physiological foramen (14.8%). The most common physiological foramen shape was non-round . The mean of the narrow and wide physiological foramen diameter was 0.263 to 0.396 mm, 0.174 to 0.290 mm.Conclusions: The mandibular premolar generally had 1 physiological foramen, The most common physiological foramen shape was non-round. Circumference filing with conventional hand files is advocated to shape this canal, avoiding using the rotary instruments.