Magnetic resonance imaging of the temporomandibular joint.

Correct diagnosis of internal derangements of the temporomandibular joint requires both a comprehensive clinical and radiographic evaluation. Plain film tomography, transcranial radiography, arthrography and computed tomography have all been used to assess the status of the joint structures. Magnetic resonance imaging is a relatively new modality used for imaging many different organ systems. Magnetic resonance imaging of the temporomandibular joint has certain distinct advantages over previously used techniques in evaluating patients for internal joint derangements. The applicability of magnetic resonance imaging in the diagnosis of internal derangements will be discussed.

Tetracycline: levels of achievable in gingival crevice fluid and in vitro effect on subgingival organisms. Part II. Susceptibilities of periodontal bacteria.

The sensitivity to tetracycline of 345 bacterial isolates from periodontal lesions was determined. Most species of bacteria, including those thought to be involved in the initiation and progress of destructive periodontal disease, were inhibited in vitro by tetracycline concentrations of 4 to 8 micrograms/ml. This concentration is equivalent to crevicular fluid levels of tetracycline at dosages of 1 gm/day. These data indicate that tetracycline is inhibitory at levels achieved in crevicular fluid for bacteria currently implicated in destructive periodontal disease.

Agar medium for use in susceptibility testing of bacteria from human periodontal pockets.

An agar medium (medium V) was formulated to determine the minimal inhibitory concentrations (MICs) of antimicrobial agents for bacteria encountered in human periodontal pockets. The medium contained (per liter) Trypticase, 15 g; yeast extract, 5 g; sodium chloride, 5 g; glucose, 2 g; sodium pyruvate, 2 g; sodium formate, 1 g; sodium fumarate, 1.5 g; sodium succinate, 0.1 g; Tween 80, 0.25 ml; agar, 15 g; hemin, 5 mg; and menadione, 0.5 mg. The growth of 50 oral strains was compared on this and six other media which included: Wilkins-Chalgren agar, Schaedler agar, Brucella agar, Trypticase-soy blood agar, and Schaedler and Brucella agars supplemented with whole blood. Growth, for most strains, was greatest on medium V. Medium V was also compared with Wilkins-Chalgren agar, using the same oral strains, to determine the MICs of the following antibiotics: penicillin, tetracycline, chloramphenicol, clindamycin, and erythromycin. The MICs of these antibiotics were essentially the same on both media when growth was quantitatively similar.