[Dental ankylosis diagnosed by CT with tridimensional reconstructions]. / L'ankylose dentaire: diagnostic par tomodensitométrie et reconstruction tridimensionnelle.

The etiology of unerupted teeth often is difficult to establish. It may relate to abnormal orientation of the tooth bud, an anatomical obstacle, pathology of the dental sac or ankylosis. The ankylosis process and diagnosis are analyzed in this clinical series. Ankylosis and its underlying physiological process are abundantly described in the literature. Nonetheless, diagnosis remains difficult to achieve. Clinical evaluation and complementary radiographic techniques such as dental radiographs and orthopantomogram are considered by some authors as poorly reliable. These clinical examinations based on a series of subjective criteria cannot be performed on unerupted teeth. In a series of patients with unerupted or retained teeth of undetermined etiology or with traction failure, 15 were diagnosed with ankylosis. The diagnosis of ankylosis could not be achieved based on clinical or radiographic evaluation and required CT imaging. Source images along with tridimensional reconstructed images were evaluated using the MVS software (Hospices Civils of Lyon). The radicular volume involved by ankylosis could be measured and its exact location on the tooth could be demonstrated. This imaging technique with tridimensional reconstruction provided positive diagnosis of ankylosis.

[Evaluation of 3D imaging software to study computed tomography images of middle ear defects]. / Evaluation d'un logiciel de reconstruction 3D à l'étude TDM des malformations de l'oreille moyenne.

OBJECTIVE: Evaluate the contribution of original 3D reconstruction software based on the principle of region growing segmentation of CT images to diagnosis of ossicular malformations of the middle ear. METHOD: Prospective study on a population of ten patients presenting uni- or bilateral transmission deafness. Twenty ears were studied using multislice CT. All the data were treated using original software segmentation based on the principle of region growing segmentation. The 3D images were compared with the original CT slices to judge the software's potential contribution to the management of these patients. RESULTS: All the images obtained were deemed of sufficient diagnostic quality. The two normal ears on the CT slices were also found to be normal on the 3D images. Typical CT images of otospongiosis found in two patients were not visible on the 3D images. The 18 ossicular malformations were well analyzed on the images obtained, which also provided better visualization of the abnormalities and associated lesions (particularly the anomalies in facial nerve position), thus providing quality surgical planning as judged by the surgeon. CONCLUSION: The image reconstruction method studied, using region growing segmentation seems to be, in this limited sample, a useful complement to classical CT images in the study of constitutional abnormalities of the middle ear.

Three-dimensional modeling system for unilateral mandibular bone distraction: a clinical case.

Facial hemiatrophies are anomalies of the first branchial arch and affect one in 4000-5000 newborns. Bone distraction is the technique of choice for the treatment of these dysmorphoses. Mandibular osteodistraction requires prior determination of the characteristics of the distraction vector whose three components will serve to activate the distractor. The patient, aged 5 years, presented with a right facial hemiatrophy, Grade IB according to the classification of Pruzansky. Tomodensitometric acquisition was obtained with a CT scanner. Software specifically designed for this application allows segmentation of the anatomical elements by a region-growing algorithm. The 3D representation of each element is added to a 3D scene, in which are placed the built-up landmarks necessary for the surgical simulation after 3D cephalometric analysis. The surgical cleavage plane is oriented according to the surgeon's requirements while preserving the predominant anatomical elements. The software allows performance of rotations and translations of the bone segments rendered independently from the cleavage plane. The distances and angles covered during the virtual movement are measured at its conclusion. The aim of moving the bone segments is to render the mandibular occlusion plane parallel to the reference occlusion plane. The vertical growth of the maxilla is realized by secondary recuperation. The distractor used was of an external multidirectional type allowing elongation of the mandibular ramus and mandibular corpus, closure of the goniac angle, and lateralization or medialization of the ramus. On the 15th day, the mandibular angle was reduced by 10 degrees, which allowed closure of the anterior gap and recentering of the incisive areas by a half-cuspid. The patient presented with a complex bone deficit in the three spatial directions, which allowed the development of software for modeling the distraction. Other clinical cases will be necessary to validate this 3D imaging-based technique.

[Three-dimensional modeling of mandibular distraction]. / Modélisation tridimensionnelle de la distraction mandibulaire.

Facial hemi-atrophy affects 1 in 4000 or 5000 children. We propose treating this deformation of the 1st branchial arch with the "bone distraction" lengthening technique first described by Ilizarov in the 1950s, which has already been employed with the mandible. We have modelled mandibular distraction in facial hemi-atrophy patients and discuss the benefits of such pre-surgical planning encompassing the assistance of pre- and post-operative as well as surgically coordinated orthodontic therapy. Using X scanner views of a 5 year-old girl patient, we have developed a distraction-simulation software, which makes the pathological side harmonious with the healthy side along the medial sagittal plane. In order to obtain facial symmetry, put bones in balance, and orient the occlusal plane horizontally, essential requisites of occlusal stability, it is necessary: to employ a 2 or 3-dimensional distractor, to pre-plan the distraction and screw positioning, to set up a fixed orthodontic treatment plan prior to beginning distraction therapy.

Precise dental implant placement in bone using surgical guides in conjunction with medical imaging techniques.

The use of medical imaging techniques to make a very precise surgical guide for implant placement is described. This template is the combination of a currently used template and a very simple mechanical system designed to transfer a preoperatively defined implant position onto the surgical site. With the planning software, the practitioner determines the implant position according both to the ideal position dictated by the final restorative prosthesis and the available volume of bone. The surgical template then communicates the actual implant position to the surgical site. The template can be used not only in critical anatomical situations but also in placing the implant in an ideal position on bone because it eliminates possible manual placement errors and matches planning to prosthetic requirements.

Florid cemento-osseous dysplasia: Report of a case documented with computed tomography and 3D imaging.

Florid cemento-osseous dysplasia is an uncommon disease of the jaws. This article reports the case of a 49-year-old black woman who was diagnosed with florid cemento-osseous dysplasia on the basis of conventional radiographic findings. Computed tomography and three-dimensional imaging of the mandible were performed, and they enabled detailed localization of the bone defects. The role of computed tomography in the evaluation of cemento-osseous lesions is discussed.

Marsupialization of dentigerous cyst associated with foreign body using 3D CT images: a case report.

This paper documents a marsupialized dentigerous cyst associated with an amalgam. The surgical challenge was removing the amalgam from the cystic lining with zero visibility. To achieve this, the surgical procedure was computer assisted and used 3D images. Distances between the amalgam and various anatomical landmarks were assessed in order to define a path from the top of the ridge to the amalgam. The path was reconstructed at the surgical site and the amalgam removed by suction. Orthodontic treatment was associated with surgery. Three dimensional imaging is a useful procedure for deciding on the type of surgical technique likely to minimize trauma. This report is also a contribution to the literature by reporting two dentigerous cysts associated with amalgam.

Criteria for the assessment of intrinsic performances of digital radiographic intraoral sensors.

RATIONALE AND OBJECTIVES: In sensor-based dental digital radiographic imaging systems, it should be possible to assess the intrinsic performance of the sensor by means of objective criteria, independent of the related electronic hardware and image-treatment software. METHODS: Six criteria are presented and discussed for the objective assessment and quantification of the intrinsic performance of intraoral sensors for dental digital radiography, independent of the characteristics of the subsequent image-treatment software. The criteria are signal-to-noise ratio, blooming, sensitivity, spatial uniformity, modulation transfer function, and geometric deformations. These criteria have been used to evaluate the Visualix sensor. RESULTS: For each criterion, a series of numerical data are presented as graphs. CONCLUSION: A method is proposed for objective assessment of radiographic sensors that makes it possible to compare sensors with each other and with conventional radiographs. The criteria proposed also increase understanding of digital diagnostic images and improve their clinical use.

Computer-assisted dental implant surgery using computed tomography.

Standard planning for dental implants consists of a prosthesis simulation on diagnostic casts and radiographic examination of anatomical structures. The clinician visually locates the planned trajectory on the surgical site in the patient's mouth without direct correlation between the radiographs and the anatomy. We have developed a computer assisted technique to define the optimal position of the bone implant using computed tomography to accurately place the implant in the planned position using a guide drilled into a resin splint.

The influence of basal anxiety on unstimulated parotid and submandibular saliva.

Stress modifies numerous physiological variables, such as salivary secretion. The relation between salivary constituents, biophysical variables and personality traits defined by the Cattell's anxiety scale was studied. The main result was, that in the absence of stress, no statistically significant differences are to be found between the three groups defined on the Cattell scale.

Disturbances caused by dental materials in magnetic resonance imaging.

Nuclear Magnetic Resonance (NMR) is the latest addition to medical imaging technology. This technique plays an important role in head and neck diagnosis. Radiologists may encounter patients with fixed dental prostheses that may produce image distortion on MRI scans of the face. The MRI appearances of dental prosthetic materials was studied in vitro, including precious alloys, non-precious alloys, ceramic prostheses, dental amalgam and composite materials. It was found that non-precious alloys produce large image deformations, whereas precious alloys had no effect on MRI images. An in vivo study showed the anatomical zones that were most affected on MRI scans.

[Evaluation of the orofacial and dental status of a population of leprosy patients treated with multidrug therapy in Senegal]. / Evaluation de l'état orofacial et dentaire d'une population hansénienne traitée par polychimiothérapie au Sénégal.

The orofacial lesions of untreated leprosy have long been known. Our study concentrated on the bucco-dental and facial status of 97 leprosy patients given multidrug therapy. The number of decayed teeth and of teeth missing due to extraction proved high. Clinical manifestations of leprosy in the facial region are, however, rare and lesions of the oral mucosa, while more frequent, always exhibit scarring.

Dental materials and magnetic resonance imaging.

Radiologists may encounter patients with fixed dental prostheses that may produce image distortion on MRI scans of the face and jaw. In this work, we assessed the MRI appearances of dental prosthetic materials in vitro, including precious alloys, nonprecious alloys, ceramic prostheses, dental amalgam, and composite materials. For in vivo studies, these materials were placed in the patient's mouth. Nonprecious alloys produce large image deformations, whereas precious alloys had no effect on MRI images. The in vivo study showed the anatomical zones that were most affected on MRI scans. The size of these zones produced by the presence of nonprecious alloys is influenced by the volume of the prosthesis and is related to the scanning sequence used.

Radioisotopic and biochemical determination of salivary secretion after long term psychotropic therapy.

The aim of this work was to investigate the effect of prolonged psychotropic therapy (neuroleptics and antidepressants over 5 yr on salivary secretion. The flow rate in the parotid and submandibular glands were measured separately by scintigraphy. Flow rates, total protein concentration and total IgA level were determined in the unstimulated saliva in 30 control subjects and 73 patients treated with psychotropic drugs. As evidenced by measurement of flow rates and scintigraphy, psychotropic therapy reduced the unstimulated salivary secretion from parotid glands and to a lesser extent from submandibular gland. The scintigraphic study showed a lower response to stimulation in patients than controls.

Preliminary results of nuclear magnetic resonance studies of healthy human saliva.

Relaxation times T1 and T2 of water protons for stimulated and unstimulated parotid and submandibular saliva from healthy patients were measured in the conventional way using the Bruker PC 20 Minispec. Some measurements of dispersion were also carried out. An interpretation of the average values for T1 and T2 observed in the 20 MHz range is proposed for these types of saliva in relation to biochemical composition (total proteins, amylase activity, sialic acids and hexosamins) and viscosity. For parotid saliva T2(-1)-T1(-1) correlates significantly with amylase activity. In the submandibular saliva T2(-1)-T1(-1) correlates significantly with both mucins and alpha-amylase activity.

A new appliance for the collection of human submandibular saliva.

This device has collecting cups which follow the movements of the floor of the mouth but which is kept stationary by a fixed platform on the occlusal surfaces of the teeth. The appliance can be adapted to different dental morphologies.