Livia Corpas

A comparative evaluation of Cone Beam Computed Tomography (CBCT) and Multi-Slice CT (MSCT): Part I. On subjective image quality

AIMS To compare image quality and visibility of anatomical structures in the mandible between five Cone Beam Computed Tomography (CBCT) scanners and one Multi-Slice CT (MSCT) system. MATERIALS AND METHODS One dry mandible was scanned with five CBCT scanners (Accuitomo 3D, i-CAT, NewTom 3G, Galileos, Scanora 3D) and one MSCT system (Somatom Sensation 16) using 13 different scan protocols. Visibility of 11 anatomical structures and overall image noise were compared between CBCT and MSCT. Five independent observers reviewed the CBCT and the MSCT images in the three orthographic planes (axial, sagittal and coronal) and assessed image quality on a five-point scale. RESULTS Significant differences were found in the visibility of the different anatomical structures and image noise level between MSCT and CBCT and among the five CBCT systems (p=0.0001). Delicate structures such as trabecular bone and periodontal ligament were significantly less visible and more variable among the systems in comparison with other anatomical structures (p=0.0001). Visibility of relatively large structures such as mandibular canal and mental foramen was satisfactory for all devices. The Accuitomo system was superior to MSCT and all other CBCT systems in depicting anatomical structures while MSCT was superior to all other CBCT systems in terms of reduced image noise. CONCLUSIONS CBCT image quality is comparable or even superior to MSCT even though some variability exists among the different CBCT systems in depicting delicate structures. Considering the low radiation dose and high-resolution imaging, CBCT could be beneficial for dentomaxillofacial radiology.

Peri‐implant bone tissue assessment by comparing the outcome of intra‐oral radiograph and cone beam computed tomography analyses to the histological standard

OBJECTIVES The present study aims to identify radiographic methods revealing data that are most representative for the true peri-implant bone as assessed by histology. MATERIALS AND METHODS Eighty implants were placed in 10 minipigs. To assess matching between different image modalities, measurements conducted on intra-oral digital radiographs (IO), cone beam computer tomography (CBCT) and histological images were correlated using Spearmans correlation. Paired tests (Wilcoxon test) were used to determine changes in the bone parameters after 2 and 3 months of healing. RESULTS Significant correlations between bone defect depth on IO and histological slices (r= + 0.7, P<0.01), as well as on CBCT images and histological slices (r= + 0.61, P<0.01), were found. CBCT and IO images deviate, respectively, 1.20 and 1.17 mm from the histology regarding bone defects. No significant correlations were detected between fractal analysis on CBCT, intra-oral radiography and histology. For bone density assessment, significant but weaker correlations (r= + 0.5, P<0.01) were found for intra-oral radiography vs. histology. Significant marginal bone-level changes could be observed after 3 months of healing using intra-oral radiography. CONCLUSIONS This study allowed linking radiographic bone defect depth to the histological observations of the peri-implant bone. Minute bone changes during a short-term period can be followed up using digital intra-oral radiography. Radiographic fractal analysis did not seem to match histological fractal analysis. CBCT was not found to be reliable for bone density measures, but might hold potential with regard to the structural analysis of the trabecular bone.

Chronologic and geographic variability of neurovascular structures in the human mandible

OBJECTIVES To compare the dimensions of mandibular anatomical landmarks of human mandibles of three different chronological periods and seven different geographic regions. METHODS Cone beam computed tomography (CBCT) images were acquired from human mandibles of three different chronological periods (Neolithic, Medieval and 19-20th Century). The 19-20th Century consisted of seven human mandibular samples from different geographic locations. Image analysis consisted of comparing anatomic variability and dimensions of the mandibular, lingual and incisive canals, mental foramen and their relationship to specific reference teeth as such to determine geographic region and historic period variabilities. RESULTS There were statistically significant differences between the 19-20th Century group and the Medieval and Neolithic groups. The 19-20th Century group differed significantly in mandibular canal diameter, tooth root length, length of the lateral lingual canal. In addition, the group also differed from the Medieval sample for the lateral lingual foramen diameter and the midline lingual canal length. Furthermore, the prevalence of anatomic variations was significantly different for the geographic samples tested, with double mental foramina significantly more present in the Congolese sample, and significantly more lateral lingual canals noted in Indonesian and Greenland Eskimo samples. CONCLUSIONS This study suggests that mandibular neurovascularisation may show some geographic as well as historic variation. Further studies on larger data samples are needed to verify this statement, as such that it can be potentially used in anthropology and forensic dentistry. More research is also needed to address whether the geographic and historic variations are linked, as well to investigate evolutionary trends in these structures.

Spontaneous Resolution of a Central Giant-Cell Granuloma After Incisional Biopsy: A Case Report

[Couto Souza, Paulo H.] Pontificia Univ Catolica Parana, Curso Odontol, Ctr Ciencias Biol & Saude, Sch Dent, BR-80215901 Curitiba, Parana, Brazil. [Jacobs, Reinhilde; Corpas, Livia S.] Catholic Univ Leuven, Fac Med, Oral Imaging Ctr, Louvain, Belgium. [Lambrichts, Ivo] Univ Hasselt, Dept Basic Med Sci, Fac Med, Hasselt, Belgium.

Histomorphological study of myelinated nerve fibres in the periodontal ligament of human canine

Abstract Objective. This study aims to describe the human periodontal ligament (PDL) using serial sections, with a focus on mechanoreceptor distribution and morphology. Materials and methods. One permanent lower canine with surrounding PDL and alveolar bone tissues was retrieved from a human cadaver. After being embedded into paraffin block, the canine was horizontally cut in 6 μm thick serial sections. At root levels of 0.3, 1.5, 3, 4.5 and 6 mm from the apex, five slices each level were evaluated. Immunocytochemisty was performed on the same serial sections, enabling a more reliable description of neural structures. Results. The distribution of myelinated fibres varied from apical to coronal level, with a total number of 38 at 0.3 mm from the apex, 25 at 1.5 mm, 25 at 3 mm, 31 at 4.5 mm and 32 at 6 mm. At all times, mesial and buccal regions were typically more densely innervated (p < 0.01) except at the 3 mm level. The average density of myelinated nerve fibres increased by arriving closer to the apex. However, the average diameter did not show any significant differences amongst quadrants or root levels (p > 0.05). The average diameter of myelinated fibres varied between 5.3–7.8 μm. Grouped myelinated axons were twice as common as isolated ones, with the innervation being rather close to the alveolar bone. Isolated myelinated axons showed a tendency to group around large blood vessels. Conclusion. The present results add to the understanding of human PDL innervation, indicating dense innervations by myelinated nerve fibres in close proximity to collagen fibres and alveolar bone. It also reveals that apical as well as mesial and buccal sites of the human canine are more densely innervated.