Effect of interference of metallic objects on interpretation of T1-weighted magnetic resonance images in the maxillofacial region.

PURPOSE: Metallic objects produce artifacts on magnetic resonance (MR) images. However, studies on typical dental materials in this area are scant. This study was conducted to describe and measure the magnitude of such artifacts. MATERIALS AND METHODS: Samples of various dental materials (dental gold, amalgam, stainless steel, titanium, silver-palladium, and vitallium) were embedded in bovine muscle and then subjected to T1-weighted MR imaging. The materials were of the typical morphology and composition encountered in routine maxillofacial practice. The MR artifacts were measured and compared with the original specimen measurements. RESULTS: All metallic objects were found to produce artifacts and to interfere with the interpretation of MR images. Artifacts were most pronounced in the central plane of the object. Gold produced the greatest artifact, and amalgam produced the least. CONCLUSION: Because metals commonly used in the maxillofacial region all produce artifacts on MR images, avoidance measures should be used to minimize the effect of these artifacts.

Multiple idiopathic resorption in the primary dentition: review of the literature and case report.

Resorption of primary teeth is a normal physiologic process, except when it occurs prematurely. Resorption of permanent teeth is considered abnormal, and multiple etiologic factors have been implicated. A significant number of cases are represented by idiopathic resorption. Multiple idiopathic root resorption stands as a separate physiologic entity that has been described as affecting the entire permanent dentition. Multiple idiopathic resorption of primary teeth has not been previously reported. A case is described and a differential diagnosis is provided. The specific radiographic diagnostic criteria for this condition affecting the primary dentition are outlined.

Arteriovenous malformation of the mandible: report of a case with a note on the differential diagnosis.

Arteriovenous malformations are extremely rare conditions that can result from congenital or acquired abnormalities in the structure of blood vessels; they are potentially fatal. Arteriovenous malformations may be asymptomatic or may show various signs and symptoms including soft tissue swelling, pain, changes in skin and mucosal color, erythematous and bleeding gingiva, bruit, and paresthesia. Radiographically, there are no pathognomonic features. The present case illustrates an arteriovenous malformation in a 16-year-old Hispanic female. The case report is unique because the malformation was previously interpreted as a pathosis of pulpal origin and was initially treated as such, although the tooth showed no gross or radiographic dental caries. A broad view of the diagnostic imaging, radiographic differential diagnosis, treatment, and histopathologic description is also presented.

Geometric considerations of disk repositioning procedures.

One approach to treatment of internal derangements of the temporomandibular joint (TMJ) is surgical remodeling and repositioning of the disk and its attachments. Nine joints exhibiting disk displacements (four histological series and five magnetic resonance imagining (MRI) series) were studied to analyze the geometrical and mechanical implications of surgical repositioning. In the central tomographic plane, for example, these cases would have required repositioning the disk 6.9 mm posteriorly (+/- 3.3 mm), removing 5.2 mm (+/- 1.6 mm) of remodeled retrodiskal tissue, and trimming 2.1 mm (+/- 2.0 mm) of disk. This suggests that from gross geometric considerations alone, there is not sufficient viable joint tissue to recommend disk repositioning as a routine procedure.

Imaging of internal derangements and synovial chondromatosis of the temporomandibular joint.

Magnetic resonance (MR) imaging of internal derangements and synovial chondromatosis is described. The MR findings of fluid collections, increased vascularity, partial disc displacement, and changes in disc morphology and length are among those factors that influence surgical execution. Fast imaging is particularly useful in delineating fluid and vascularity changes. Synovial chondromatosis is an entity characterized by large intra-articular fluid collections and is thus ideally evaluated using MR imaging.

Crystal methamphetamine abuse: a concern to oral and maxillofacial surgeons.

Synthetically manufactured methamphetamine ("ice," "crystal") appears to be undergoing a rebirth in popularity because experienced drug users are reportedly unable to distinguish between the qualities of the cocaine and methamphetamine euphoria. Like cocaine, adverse drug reactions with therapeutic drugs used in dentistry have been reported, ranging from mild intoxication to sudden death. This article discusses the pharmacology of this illicit drug and the problems associated with its use in patients undergoing oral and maxillofacial surgery.

Superficial vascularity of temporomandibular joint retrodiskal tissue: an element of the internal derangement process.

Superficial vascular changes in the retrodiskal tissue are an aspect of the remodeling process during progressive anterior displacement of the temporomandibular joint (TMJ) disk. The salient portion of the remodeled retrodiskal tissue (RRT) is contained in a 3 x 3 grid of arthroscopic fields in the superior joint space, plus the tympanic portion of the remodeled retrodiskal tissue. A four-level vascularity classification system gives a statistically significant association between superficial avascularity of the remodeled retrodiskal tissue and progressive stages of disk derangement. In particular, simultaneous avascularity in both the tympanic remodeled retrodiskal tissue and the central arthroscopic field occurs with severe disk displacement without reduction. Analyses are based on 16 microscopic studies, 25 magnetic resonance imaging and tomographic imaging studies, and 26 arthroscopic studies.

Facial muscle reanimation using the trigeminal motor nerve: an experimental study in the rabbit.

Surgical repair of facial nerve deficits may be marred by lack of muscle control and donor region paresis. Using New Zealand white rabbits, a study was undertaken to evaluate facial muscle reanimation with a donor source not previously used: the motor division of the trigeminal nerve. The results were compared with the severed facial nerve and hypoglossal-facial coaptation. An atrophy scale was calibrated for facial muscles of the rabbit. Clinical, electromyographic, and histomorphometric findings confirmed that the trigeminal nerve was a suitable donor source. The neurorrhaphy produced an exponential rate of repair.