Steven L. Jordan

A classification of temporomandibular joint disk morphology.

Disk morphology has been recognized as an important feature of internal derangements of the temporomandibular joint and as a suspect in functional impediments. A classification of disk shapes was devised by means of corrected lateral cephalometric arthrotomograms and histopathologic sagittal sections. Five basic shapes were identified: bow tie (normal), straight, funnel, bulge, and Y. Statistical analyses were performed. The normal condyle-disk-fossa relationship and slight-to-moderate disk displacement occurred with disk shape 1 (bow tie). Severe disk displacement without reduction occurred predominantly with disk shape 4 (bulge). Beaking of dye in the anterior recess of the inferior joint space was an indicator of abnormal disk morphology and displacement.

Determination of the radiographic position of the temporomandibular joint disk

We describe a method of measuring displacement and reduction of the temporomandibular joint (TMJ) disk that makes use of reproducible geometric measurements from radiographs in the sagittal plane. This procedure leads to a simple quantitative classification scheme for condyle-disk-fossa/eminence relationships. The method was applied to microscopic sections of 12 human TMJs and then to 30 complete lateral corrected cephalometric arthotomographic studies of the TMJ. Statistical analyses of the classification scheme confirm that it is highly significant and consistent with clinical diagnoses.

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.

Accuracy of temporomandibular joint space measurements using corrected hypocycloidal tomography

This study underscores the importance of obtaining radiographs in a tomographic plane bisecting the long axis of the condyle. The accuracy of joint relationships and clarity of the images produced using the horizontally and vertically corrected techniques were significantly greater than when both standard or only horizontally corrected techniques were used in the cases examined. Correlative clinical studies are recommended to be studied.

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.

A microprobe study of element distribution in vaginal epithelial cells of the rat

Microprobe analysis of vaginal epithelial cells shed during the estrous cycle of the rat was done to determine cellular elements present in successive stages: pro‐estrus, estrus, and post‐estrus. Smears of vaginal contents were placed on carbon planchettes, fixed by freeze‐drying, and examined in a scanning microscope with an energy dispersive spectrometer. Concentrations of Na, Mg, P, S, Cl, K, and Ca were calculated (mmol/kg dry weight) and analyzed statistically. For phosphorus a significant fall at estrus correlates with a loss of nuclear and cytoplasmic nucleic acids and nucleoproteins. An increase in sulfur at estrus is consistent with an accumulation of keratins over pro‐estrus and a greater increase over the post‐estrus epithelial cells. The epithelial cells of pro‐estrus are highest in Mg and Ca. By post‐estrus, the cells have recovered their Mg, not Ca. Potassium concentrations exhibited no significant change between the successive stages.

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.

American attempts to solve Newton's pasturage problem

Abstract Frederick Emersons North American Arithmetic contained a “pasturage problem” which baffled his compatriots. Actually, as the Americans discovered forty-two years later, this problem was taken from Isaac Newtons Arithmetica Universalis. The history of this problem illuminates the tradition of standard artificial exercises, the isolation of American mathematics, a chain of mathematical and historical plagiarisms, and changing patterns of arithmetical reasoning.

Quantitative Radiological Diagnosis Of The Temporomandibular Joint

Recent impressive technological advances in imaging techniques for the human temporomandibular (tm) joint, and in enabling geometric algorithms have outpaced diagnostic analyses. The authors present a basis for systematic quantitative diagnoses that exploit the imaging advancements. A reference line, coordinate system, and transformations are described that are appropriate for tomography of the tm joint. These yield radiographic measurements (disk displacement) and observations (beaking of radiopaque dye and disk shape) that refine diagnostic classifications of anterior displacement of the condylar disk. The relevance of these techniques has been clinically confirmed. Additional geometric invariants and procedures are proposed for future clinical verification.

Factoring 111 ... 11 — A stimulating problem

The problem of factoring numbers like 111, 111, 111, 111 is a very productive one. It is beguiling, for in spite of its trivial appearance, this factoring problem leads immediately to considerations of the algebra of polynomials, ring homomorphisms, roots of unity, programming, repeating decimals, and recreational mathematics. This article shows how a pre‐calculus class can be introduced naturally to such ideas. Many of these applications are traditionally considered advanced, and will reappear in a students curriculum. A table of 56 factorizations is presented ; the largest is R45 =111, 111, ..., ..., 111. The article follows with an annotated list of applications of the factoring problem (focusing on 111, 111, 111, 111), which have been used successfully with pre‐calculus students. The techniques and comments are geared to the teacher of such a course.