Diagnostic accuracy of film-based, TIFF, and wavelet compressed digital temporomandibular joint images.

The purpose of this research was to determine if digitization and the application of various compression routines to digital images of temporomandibular joint (TMJ) radiographs would diminish observer accuracy in the detection of specific osseous characteristics associated with TMJ degenerative joint disease (DJD). Nine observers viewed 6 cropped hard-copy radiographic films each of 34 TMJs (17 radiographic series). Regions of interest measuring 2 in x 2 in were digitized using an 8-bit scanner with transparency adapter at 300 dpi. The images were placed into a montage of 6 images and stored as tagged image file format (TIFF), compressed at 4 levels (25:1, 50:1, 75:1, and 100:1) using a wavelet algorithm, and displayed to the observers on a computer monitor. Their observations regarding condylar faceting, sclerosis, osteophyte formation, erosion, and abnormal shape were analyzed using ROC. Kappa values were determined for relative condylar size and condylar position within the glenoid fossa. Indices were compared using ANOVA at a significance level of P < .05. Although significant and substantial observer variability was demonstrated, there were no statistically significant differences between image modalities, except for condylar position, in which TIFF and wavelet (at all compression ratios) performed better than the original image. For faceting, wavelet 100:1 performed better than radiographic film images. Little actual image file reduction was achieved at compression ratios above 25:1.

Submentovertex radiology: cephalometric considerations in temporomandibular dysfunction.

Controversy exists in the literature concerning the association between the radiographic and the clinical features of the temporomandibular dysfunction (TMD). Hence, this study reinvestigated possible correlations between radiographically detected asymmetries and the clinical signs and symptoms of TMD. Complete clinical and radiographic records were gathered from 52 patients sequentially referred for corrected angle tomographs of the temporomandibular joint (TMJ). Measurements from submentovertex (SMV), lateral and posterior-anterior (PA) cephalographs and corrected angle parasagittal tomographs and recorded clinical signs and symptoms of TMD were the data inputs. Significant findings were as follows: a) as the discrepancy in the posterior condyle to pogonion measurement increased, the pogonion and both maxillary and mandibular incisors shifted laterally towards the shorter side; b) as the ANB angle increased, so did the difference in condylar angle measurements between the two condyles; c) the side with the larger condylar angle was positioned forward on the SMV; and d) a perpendicular bisector (Marmary's Centerline) of the line drawn between the right and left foramen spinosum was found to be a reliable baseline reference for SMV analyses. No statistically significant relation was found linking specific signs and symptoms of TMD to maxillofacial asymmetries recorded on SMV, lateral or PA cephalographs. None of the radiographic signs studied were found to be good predictors of specific signs and symptoms in TMD.

An aid to stop thumb sucking: the "Bluegrass" appliance.

A nonpunitive fixed appliance utilizing a Teflon (E.I. du Pont de Nemours and Co., Inc., Wilmington, DE) roller is described. The appliance is used in conjunction with a program of positive reinforcement in managing thumb sucking in children 7-13 years of age. It has been used successfully in 24 children, with no cases requiring reinsertion.

Auxiliary springs in continuous arch treatment: Part 2. Appliance use and case reports.

In the second part of this series, three clinical examples are presented to illustrate the use of auxiliary space-closure springs with clinically manageable moment-to-force ratios and new canine brackets to accommodate these springs within the framework of conventional and straight-wire 0.018-inch appliance systems. Eligiloy retraction spring models (0.1650 inch x 0.02150 inch) in the edgewise mode were developed for translational movements along a main archwire. The effects of different preactivation bends for influencing intraarch anchorage are shown for the conditions of reciprocal closure, posterior protraction, and anterior retraction.

Auxiliary springs in continuous arch treatment: Part 1. An analytical study employing the finite-element method.

This report describes the results of a finite-element analysis with ANSYS (Version 4.3) from Swanson Analysis Systems and 1 mm-long, 2-D elastic beam elements to modify and refine the designs of maxillary and mandibular springs for space-closure management. This system permitted static analysis by means of modern software systems instead of expensive and cumbersome mechanical bench studies. Our examination of anterior and posterior reactions led to what we believe are optimal designs with clinically manageable moment/force ratios and new canine brackets that accommodate these springs within the framework of conventional and straight-wire appliance systems. Three degrees of freedom were used at each node for translations in the x and y directions and a rotation about the z axis, producing 182 elements with 183 nodes for the mandibular model and 146 elements with 147 nodes for the maxillary model. Elgiloy retraction spring models (0.1650 inch x 0.02150 inch) in the edgewise mode were developed so that the effects of three different preactivation bends could be refined by computer analysis. Sixty-four analyses were performed for each spring, with each of three angle bends (theta 1, theta 2, and theta 3) varied from 0 degrees to 45 degrees in 15 degrees increments. The employment of this computer method promises to simplify the design and development of complex interacting orthodontic systems. Clinical cases are presented in Part 2 of this series, which illustrates the application of auxiliary springs.

Exploitation of the residual premaxillary-maxillary suture site in maxillary protraction. An hypothesis.

A discussion of the patency of the maxillary-premaxillary suture and its possible value in orthopedic protraction of the premaxillary segment, illustrated by a case report.

The human chin and its relationship to mandibular morphology.

This study evaluated the proportion of the external chin (protuberantia mentalia) in relation to the total symphyseal area in normal jaws and those with a diverse morphology. A sample of 60 cases was randomly selected and divided into three groups of 20 each on the basis of normal growth, horizontal growth and vertical growth with an open bite. Tracings of lateral dn frontal radiographs were used to describe general mandibular form and to determine the percentage of external/total symphyseal area. Dental casts were also examined to determine a basal arch form ratio. The results of this study indicate that the amount of bony chin present is related to certain morphologic features of the mandible. The most significant findings illustrate: 1. The chin increases in size as the mandibular type varies from a vertical type, to a normal type, to a horizontal type of growth pattern. 2. With dental "hypofunction" in combination with an exaggerated vertical development of the mandible, a smaller proportion of the protruding chin is present. 3. The chin increases in size as the mandibular basal arch form varies from a tapered shape for the vertical cases to a more square form in the horizontal cases. 4. The degree of lateral ramal flair does not appear to influence the proportion of protruding chin present. Several models have been presented which attempt to explain protuberantia mentalia variation. The evidence in this study supports the concept that mandibular morphology is the result of the action of compensative adaption in a developing structure. There appears to be an implied polygenic influence on symphyseal morphology operating from the cartilaginous cranial base and mandibular basilar bone. This may be manifested in the relative proportion of mandibular basal bone to cranial base width, and to the vector of cranial base growth. The ultimate proportion of the bony chin is viewed to be the result of mandibular adaption to a functional musculoskeletal balance in the craniofacial complex. The extreme variability of chin form in man may be considered to be the result of compensative growth developing in response to the most structurally efficient jaw form, the contiguous soft and hard tissue environment, and the intrinsic genotype of the mandible.

Association of aircraft noise stress to periodontal disease in aircrew members.

A review of the literature reveals a multitude of effects that noise may contribute to periodontal disease, including cardiovascular disease, angiospasm of peripheral vessels, hypertension, and an increase in inflammatory cells with concurrent inhibition of healing. Three groups of 25 men were selected from the Pennsylvania Air National Guard for study. Group 1 consisted of F-102 jet fighter pilots; Group 2, pilots and crew of a four-engine, propeller-driven C-121 aircraft; and Group 3, enlisted men not exposed to aircraft noise, as a control. The degree of alveolar, intraceptal bone loss for each subject was measured from full-mouth radiographs of all groups. The greatest amount of bone loss occurred in crew members of propeller-driven aircraft. Jet pilots had considerably less bone loss while the average number of millimeters of bone lost per tooth revealed a difference between the three groups to the 0.01 significance level (F=24.7). The data suggests there is a degree of alveolar bone loss over a period of years associated with exposure to propeller aircraft noise and vibration, and negligible loss for jet aircraft noise.