Three-Dimensional Radiographic Evaluation of the Malar Bone Engagement Available for Ideal Zygomatic Implant Placement.

Zygomatic implant rehabilitation is a challenging procedure that requires an accurate prosthetic and implant plan. The aim of this study was to evaluate the malar bone available for three-dimensional zygomatic implant placement on the possible trajectories exhibiting optimal occlusal emergence. After a preliminary analysis on 30 computed tomography (CT) scans of dentate patients to identify the ideal implant emergencies, we used 80 CT scans of edentulous patients to create two sagittal planes representing the possible trajectories of the anterior and posterior zygomatic implants. These planes were rotated clockwise on the ideal emergence points and three different hypothetical implant trajectories per zygoma were drawn for each slice. Then, the engageable malar bone and intra- and extra-sinus paths were measured. It was possible to identify the ideal implant emergences via anatomical landmarks with a high predictability. Significant differences were evident between males and females, between implants featuring anterior and those featuring posterior emergences, and between the different trajectories. The use of internal trajectories provided better bone engagement but required a higher intra-sinus path. A significant association was found between higher intra-sinus paths and lower crestal bone heights.

Contribution to the radiological study of the eosinophilic granuloma of the mandible (unifocal granuloma due to Langerhans' cell histiocytosis).

PURPOSE: The radiological diagnosis of osteolytic lesions of the mandible still constitutes a challenge in some pathological conditions in which the clinical data and the case history are relatively uniform and the radiological picture is lacking in any characteristics. MATERIALS AND METHODS: We reviewed the conventional radiograms of six cases of Langerhans' cell histiocytosis (LCH) of the mandible examined over the last ten years. The X-ray examinations were performed in the lateral-oblique projection to allow a view of the horizontal portion of the mandible almost completely free of overlapping images of other bone structures. RESULTS: We identified a series of radiological patterns for these reticulo-endotheliopathies capable of causing granuloma formed by polynuclear eosinophils, plasma cells, lymphocytes, and large mononuclear macrophages with granulopexic and phagocytic activity that proliferate in the bone tissue and can be identified as the Langerhans' cells of skin, mucosa, periodontal cavities and bone marrow. The granulomatous tissue penetrates the affected organ elements and, in its spread, it compresses, atrophies, and destroys the damaged tissue, replacing it. The alterations produced by Langerhans' cell histiocytic granuloma are most common in the skeletal system affecting, in order of frequency, the skull, the long bones of the limbs, the foot, the ribs and the spine. The oral mucosa is rarely involved. CONCLUSIONS: The radiological investigation of unifocal Langerhans' cell histiocytic granuloma of the mandible is essential in the study of perimandibular swelling, although diagnosis is based on biopsy alone. In addition to digital or conventional radiography, other useful examinations are bone scintigraphy, Colour Doppler US, MR and CT, which enables a correct localisation necessary for planning the biopsy and treatment.