Morphology of the physiological foramen: II. Maxillary and mandibular premolars.

INTRODUCTION: Information concerning the anatomy of the physiological foramen is still limited. The aim of this study was to investigate the distance between the physiological and anatomical apex, the shape and diameter of the physiological foramen in maxillary (Mx) and mandibular premolars (Mn).

METHODS: The anatomy of the apex of 229 maxillary (first: MxP1; second: MxP2) and 221 mandibular premolars (first: MnP1; second: MnP2) from a mixed Swiss-German population was investigated by means of micro-computed tomography and 3D software-imaging.

RESULTS: The following results was obtained in the presence of a main physiological foramen: a. The distance between the physiological and anatomical foramen were 0.29-0.99 mm (MxP1), 0.21-1.03 mm (MxP2), 0.13-0.8 (MnP1), and 0.15-1.41 (MnP2) b. The mean narrow and wide diameters of the physiological foramen were 0.19-0.33 mm (MxP1), 0.25-0.42 mm (MxP2), 0.28-0.37 (MnP1), and 0.28-0.40 (MnP2) c. The most common physiological foramen shape was oval (66.7% MxP1, 89.7% MxP2, 91.8% MnP1, 64.4% MnP2) CONCLUSION: Considering the recommended preparation sizes based on a size corresponding to the friction, i.e. at the narrowest point in the area of the apical constriction (physiological foramen), and within the limitations of this ex vivo micro-CT study, a final preparation size could be chosen when considering the pertaining morphological considerations; yet, to a minimum ISO 30 size.