Surgical implications of the anatomic situation of the mandibular canal for mandibular osteotomies: a cone beam computed tomographic study.

PURPOSE: In bilateral sagittal split osteotomy (BSSO), the risk of lesion of the inferior alveolar nerve (IAN) is important. The aim of this study was to investigate the situation of the IAN in the area of the BSSO in preoperative 158 CBCT. METHODS: The situation of the mandibular canal (MC) has been studied in six coronal sections (one section each 4 mm) from the proximal root of the second mandibular molar. The height of the MC related to the height of the mandible, and the horizontal distance between the MC and the lateral cortical plate related to the mandibular width have been determined in each section. The cancellous bone width has been measured allowing to determine a cancellous bone ratio. RESULTS: The variability of the MC was high, depending mainly on the cancellous bone ratio which was higher when the IAN was deep. When a third molar was present, the MC was lower in the area of the third molar. CONCLUSIONS: To decrease the risk of injuring the IAN in BSSO, the evaluation of the cancellous bone ratio by a preoperative CBCT may be proposed to adapt the surgical technique to the anatomy.

[Cone Beam computerized tomography and implants]. / Imagerie Cone Beam et implants.

The authors, both working as radiologist in private practice, have initiated the Cone Beam technique as soon as 1999 and report their own experience. Cone Beam Computerized Tomography (CBCT) is dedicated to hard tissues imaging thus specifically adapted to oral implantology and maxillofacial surgery. It has the advantage to deliver low dose radiation, compared to other techniques. CBCT permits anatomical volume acquisition. After data analysis on computer, distances and implants 3D simulation can be checked. CBCT differs from CT scan because it is more adapted to hard tissues, it has a better resolution than CT, and because it delivers lower doses. Its isotropic pixel particularity which gives exact linear measurements, and the fact that metallic artifacts are significatively diminished, gives CBCT its high interest in implantology. These advantages of CBCT and the small place needed for its installation explain its global wide spreading. CBCT is now considered to be the gold standard in dental and maxillofacial sectional imaging. Because of its biomeasuring capacity, its bi- and tridimensional reconstruction possibilities, its surgical navigation and simulation capacity, it is now widely used in implantology.

[Diagnostic means using oral and maxillofacial cone beam computed tomography: results]. / Moyens diagnostiques en imagerie odonto-stomatologique cone beam: résultats.

Every imaging test is justified by clinical facts and optimized to reduce the X-rays dose delivered to patients. If results from orthopantomogram are inadequate, a cross-sectional tomographic technique is indicated. Today, cone beam computed tomography yields images comparable to CT scan or even better. Some dedicated cone beam machines allow the study of small volumes with a very high definition. Dental and maxillofacial imaging as a whole, including endodontic imaging, formerly dreaded by imagers, is now accessible to cross-sectional imaging.

Investigation of NMR limits of detection for implantable microcoils.

Although NMR has the ability to investigate biological systems non-destructively, its low sensitivity primarily has hampered their investigation compared to other analytical techniques. Therefore, optimi zing radio frequency (RF) coils to improve sensitivity do offer benefits in MR spectroscopy (MRS). Sensitivity may be improved for mass- and volume-limited samples if the size of the detection RF coils matches the sample size. In this paper, the mass- and concentration-limit of detection (LOD(m), LOD(c)) for an implantable microcoil will be estimated by MRS measurements and then compared with their analytical values. For a sample containing a solution of several cerebral metabolites, for the Choline case, the LODm is 5.7 . 10(-9)mol and LODc of 3.8 mM. These preliminary results enable to open largely the biomedical applications based on cerebral metabolism investigation on small animal experiments.

NMR planar micro coils for micro spectroscopy: design and characterisation.

The goal of this study is to determine the concentration sensitivity and the limit of detection of a SNMR receiver planar micro coil with ellipsoidal geometry 1000x500 microm, fabricated using an electroplating technique and used as SNMR receiver coil at 200 MHz. The maximum signal intensity on the NMR images and simulation of RF field distribution allows defining an active volume of 0.8 microL. The localised spectroscopy based on a PRESS sequence shows that the concentration sensitivity is closed to S(C)=2.33 M(-1) and the limit of detection LOD=0.8 M. This micro-system offers the possibility of new investigation techniques based on implantable micro coils used for in vivo study of local cerebral metabolites occupying a small volume (microL to nL order).

[Stafne's lacuna, a salivary inclusion in the mandible. Apropos of a case]. / La lacune de Stafne, inclusion salivaire dans la mandibule. A propos d'une observation.

Clinically asymptomatic, a radiolucent area in the body of the mandible was discovered on the panoramic radiograph, during a routine examination. The first diagnosis was cyst, but sialogram and CT showed a bone defect on the lingual mandibular wall, with an accessory salivary lobe into the bone cavity, corresponding to a Stafne's idiopathic bone cavity.