Ossifying fibroma and fibrous dysplasia of the jaw are maxillofacial fibro-osseous lesions that should be distinguished each other by a pathologist because they show distinct patterns of disease progression. However, both lesions often show similar histological and radiological features, making distinction between the two a diagnostic dilemma. In this study, we performed immunological and molecular analyses of five ossifying fibromas, four cases of extragnathic fibrous dysplasia, and five cases of gnathic fibrous dysplasia with typical histological and radiographic features. First, we examined the difference between fibrous dysplasia and ossifying fibroma in the expression of Runx2 (which determined osteogenic differentiation from mesenchymal stem cells) and other osteogenic markers. Fibroblastic cells in fibrous dysplasia and ossifying fibroma showed strong Runx2 expression in the nucleus. The bone matrices of both lesions showed similar expression patterns for all markers tested except for osteocalcin. Immunoreactivity for osteocalcin was strong throughout calcified regions in fibrous dysplasia, but weak in ossifying fibroma lesions. Second, we performed PCR analysis with peptide nucleic acid (PNA) for mutations at the Arg 201 codon of the alpha subunit of the stimulatory G protein gene (GNAS), which has reported to be a marker for extragnathic fibrous dysplasia. All nine cases of extragnathic or gnathic fibrous dysplasia were positive for this mutation. On the other hand, none of the five cases of ossifying fibroma showed the mutation. These findings indicate that although fibrous dysplasia and ossifying fibroma are similar disease entities, especially in the demonstration of the osteogenic lineage in stromal fibroblast-like cells, they show distinct differences that can be revealed by immunohistochemical detection of osteocalcin expression. Furthermore, PCR analysis with PNA for GNAS mutations at the Arg 201 codon is a useful method to differentiate between fibrous dysplasia and ossifying fibroma.

In adults with untreated mandibular prognathism, when the mandibular central incisor was more lingually inclined, the associated alveolar bone was also more lingually inclined and thinner. The mandibular central incisor root apex was closer to the inner contour of the labial cortical bone than to the lingual cortical bone.

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Objectives To quantitatively compare the streak artifacts produced by dental metals in a cone-beam computed tomography (CBCT) device and a multi-detector row computed tomography (MDCT) scanner in relation to metal types and imaging parameters. Methods Cubes of aluminum, titanium, cobalt-chromium alloy, and type IV gold alloy were scanned with CBCT and MDCT scanners at tube voltages of 80 and 100 peak kV (kVp), and currents of 100 and 170 mAs by MDCT, and 102 and 170 mAs by CBCT. Artifact areas were quantified using ImageJ software. Results Artifact areas for the same metals and imaging parameters were smaller with CBCT than with MDCT under most conditions. Type IV gold alloy caused the largest artifact areas, followed by cobalt-chromium alloy, titanium, and aluminum, respectively. Higher tube voltage was associated with smaller artifact areas under most conditions, whereas increasing tube current had no consistent effect on artifact area using either CT device.Conclusions CBCT was associated with smaller artifact areas than MDCT for the same parameters. Type IV gold alloy produced the largest artifact areas among the tested metals, but metallic artifacts could be reduced by increasing the tube voltage.

Although magnetic resonance imaging (MRI) is the modality of choice for evaluation of TMJ disc position, it is sometimes difficult to determine when it is displaced or reduced. The MR images of 273 Patients with a clinical diagnosis of TMJ disorders were assessed for disc position and configuration. Most (90-97%) of the slightly anteriorly displaced discs were reduced to the normal position in the open-mouth position. However, the greater part (76%) of the distorted discs was completely displaced anteriorly and without reduction. Since no distorted discs were found in the normal disc position, we conclude that discs are distorted after displacement.

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Although several investigators have reported associations between masticatory muscles and skeletal craniofacial form, there is no agreement on the association. We tested the hypothesis that masticatory muscle volume correlates with the size and form of the adjacent local skeletal sites. For this purpose, we investigated the morphological association of the cross-sectional area and volume of temporal and masseter muscles with zygomatico-mandibular skeletal structures using computerized tomography (CT) in 25 male adults with mandibular prognathism. Muscle variables significantly correlated with widths of the bizygomatic arch and temporal fossa but not with the cranium width. Masseter volume significantly correlated with cross-sectional areas of the zygomatic arch and mandibular ramus. Masseter orientation was almost perpendicular to the zygomatic arch and mandibular antegonial region. The zygomatic arch angle significantly correlated with the antegonial angle. The results of the study suggest that the masticatory muscles exert influence on the adjacent local skeletal sites.