Three-dimensional analysis of the physiological foramen geometry of maxillary and mandibular molars by means of micro-CT

Abstract

The aim of this study was to investigate the physiological foramen diameter, shape and distance between physiological and anatomical apex of maxillary and mandibular first and second molars. Accurate knowledge of the physiological foramina morphology; thus, inherent mechanical shaping technical hindrances, is decisive when taking the corresponding root canal final preparation decision. The morphological dimensions of a total of 1727 physiological foramina were investigated by means of micro-computed tomography. Mean narrow and wide (to a high number, oval) diameters of the physiological foramen were 0.24, 0.22 and 0.33 mm and 0.33, 0.31 and 0.42 mm in mesiobuccal (MB), distobuccal (DB) and palatal (P) roots in maxillary first molars; 0.24, 0.22 and 0.33 mm and 0.41, 0.33 and 0.44 in MB, DB, and P roots in maxillary second molars. Mandibular first molars showed mean narrow and wide diameters of 0.24 and 0.30 mm and of 0.39 and 0.46 mm in mesial (M) and distal (D) roots; second mandibular molars showed 0.25 and 0.31 mm and 0.47 mm in M and D roots. The mean distance between the physiological foramina and anatomical apex was 0.82, 0.81 and 1.02 mm and 0.54, 0.43 and 0.63 mm in MB, DB and P roots of the maxillary first and second molars, respectively. A mean distance of 0.95 mm (M) and 1.05 mm (D) in the first and 0.78 mm (M) and 0.81 mm (D) in the second mandibular molars was observed. Based on the results obtained, assumable recommendations for final preparation size of the physiological foramen were calculated. However, when taking into consideration, the resulting standard deviations of marginal errors must be cautiously considered when taking a final decision in clinical endodontic treatment.

Correlation of objective image quality and working length measurements in different CBCT machines: An ex vivo study

“…Although the actual working length in this investigation was determined taking the physiological foramina as reference point and under magnification, it would certainly be interesting to design a research model in which it would be established up to what point a CBCT working length determination could substitute or enhance an apex locator established one. The mean distances between the physiological foramen (apical constriction) and the anatomical apex (major foramen) can vary from 0.43 mm to 1.02mm 3 . In the investigated CBCT devices, the difference between working length and physiological foramen (apical constriction) could neither be measured nor distinguished due to the lack of imaging accuracy.…”

“…The pulp tissue was removed and the root canal patency probed to the physiological foramen with a K-file, ISO 15 (VDW, Munich, Germany). The actual working length was determined by placing a K-type file in the root canal and under microscopic observation (16x; Stemi DRC; Carl Zeiss Jena, Jena, Germany) until its tip reached the physiological foramina limit 3 . As radiological reference for the assessment of the actual working length at the physiological foramen, a small steel sphere (Ø 0.5 mm) was adhesively fixed in the access cavity.…”

“…As radiological reference for the assessment of the actual working length at the physiological foramen, a small steel sphere (Ø 0.5 mm) was adhesively fixed in the access cavity. The apical end-point was defined as the physiological foramen 3 .…”

Automated segmentation and description of the internal morphology of human permanent teeth by means of micro-CT

“…The apical foramen of the teeth was evaluated as previously described [19] by assessing the bottom part of each tooth using Fiji [32] to scroll through the stack of images and measure the diameter of the physiological and anatomical foramen as well as the distance between the physiological and anatomical foramina. The physiological (main) foramen was de ned as one with a diameter of 0.20 mm or more.…”

“…The physiological (main) foramen was de ned as one with a diameter of 0.20 mm or more. Foramina with diameters smaller than 0.20 mm were de ned as accessory ones [19]. Since we have extracted the pulpa for each tooth, we can easily calculate its diameter at each point, that is, exactly calculate the exact Euclidean distance transform (EDT) where each 3D voxel of the pulpa is labelled with its distance relative to the background (wall of the canal).…”