Quantitative analysis of bone density in direct digital radiographs evaluated by means of computerized analysis of digital images.

OBJECTIVES: minimal density variations of mineralized tissues can be reliably detected with quantitative image subtraction analysis. The aim of this study was to evaluate quantitative variations of in vitro mineral density by varying the exposure time of direct digital radiographs using a computer assisted densitometric image analysis (CADIA) program. METHODS: in a human mandibular segment a three-wall periodontal defect was created mesial to a molar. Bone chips were created from the marrowbone of the same mandible with masses of 1 to 5 mg. A triplicate radiograph of the defect was taken as a baseline for seven different exposure times. The bone chips were inserted into the defect and another triplicate series of radiographs for the seven exposure times were taken as follow-up images. The images were analysed using CADIA software to detect variations in bone density. RESULTS: the results of CADIA revealed increased density when the size of the inserted bone chip increased. The 2 mg chip was underestimated owing to mass reduction during insertion. The regression line of the CADIA values was consistent with the weight of the bone chips of 1, 3, 4 and 5 mg. The exposure time f6 (0.178 s) showed the best correlation with the bone chip weight. Loss of information in the images occurred when the exposure time exceeded the sensor's latitude. CONCLUSIONS: CADIA analysis is a reliable and sensitive tool for detecting subtle bone density variations. More reliable results are obtained with increased exposure time; however, excessive exposure should be avoided.

Mineralization of stylohyoid ligament complex in patients with temporomandibular disorders and asymptomatic individuals: a comparative study.

The incidence of mineralization of the stylohyoid ligament complex, according to radiographic findings, was analysed in a group of patients with temporomandibular disorders (TMD), and compared with that of a control group of asymptomatic individuals (AI). Both groups were similar considering the prevalence of the female gender as well as the distribution of cases according to age. 'Elongated' was the most frequent radiographic appearance in both groups; 'partially mineralized' was the most frequent radiographic pattern in the TMD group; and the lower ramus was the most frequent location of mineralization in both groups. When comparing between groups and according to each class, there was only one significant difference in radiographic appearance, 'pseudoarticulated' being more frequent in the TMD group. We can conclude that the occurrence and characteristics of mineralization of stylohyoid ligament complex were similar in TMD patients and AIs.

Remodelling of bilateral fractures of the mandibular condyle.

A case of complete remodelling of bilateral fractures of the mandibular condyle in an 11-year-old boy is presented. Initial radiographic examination revealed fractures of the right and left condylar neck with medial and anterior dislocation of the proximal fragment. The fractures were treated conservatively, with a short-time intermaxillary fixation and early jaw function, and thirty-five months later the patient was asymptomatic. Radiographic changes observed following treatment have revealed a gradual return to normal shape and position of the condyles.

Active unilateral condylar hyperplasia.

Two cases of active unilateral condylar hyperplasia which were treated with condylectomy alone are presented. The first case was an adult form and the other a juvenile form. Both were classified as active by using 99Tc bone scintigraphy. Clinical and radiographic features of both cases conformed to the hemimandibular hypertrophy type. Satisfactory facial symmetry and dental occlusion were achieved. Histopathological data confirmed the activity of the articular cartilage layers.

Radiobiologic risk estimation from dental radiology. Part II. Cancer incidence and fatality.

With the use of the measured absorbed doses from part I of this article, the specific radiobiologic risk to the patient from (1) five different panoramic machines with rare-earth screens, (2) a 20-film complete-mouth survey with E-speed film, long round cone, (3) a 20-film complete-mouth survey with E-speed film, long rectangular cone, (4) a 4-film interproximal survey with E-speed film, long round cone, and (5) a 4-film interproximal survey with E-speed film, long rectangular cone, was calculated. The estimated risks are expressed in two ways: the probability of radiation-induced cancer in specific organs per million examinations and the probability of expression of a fatal cancer per million examinations. The highest risks calculated were from the complete-mouth survey with the use of round collimation. The lowest risks calculated were from panoramic radiography and four interproximal radiographs with rectangular collimation.

Radiobiologic risk estimation from dental radiology. Part I. Absorbed doses to critical organs.

The aim of the present study was to generate one consistent set of data for evaluating and comparing radiobiologic risks from different dental radiographic techniques. To accomplish this goal, absorbed doses were measured in fourteen anatomic sites from (1) five different panoramic machines with the use of rare-earth screens, (2) a twenty-film complete-mouth survey with E-speed film, long round cone, (3) a twenty-film complete-mouth survey with E-speed film, long rectangular cone, (4) a four-film interproximal survey with E-speed film, long round cone, and (5) a four-film interproximal survey with E-speed film, long rectangular cone. The dose to the thyroid gland, the active bone marrow, the brain, and the salivary glands was evaluated by means of exposure of a tissue-equivalent phantom, fitted with lithium fluoride thermoluminescent dosimeters (TLDs) at the relevant locations.

A new technique for imaging the temporomandibular joint with a panoramic x-ray machine. Part I. Description of the technique.

A new technique for imaging the temporomandibular joint with rotational panoramic radiography is explained and demonstrated with a tissue-equivalent phantom. In this technique the patient is displaced forward and laterally away from the side under examination. Radiographs made with the proposed technique show the temporomandibular joint with more sharpness and less distortion than do radiographs made with conventional panoramic techniques.

A new technique for imaging the temporomandibular joint with a panoramic x-ray machine. Part II. Positioning with the use of patient data.

In the first article of this series, a new panoramic technique for visualization of the temporomandibular joint was described. In this article, it is shown that the patient positioning required for the implementation of this technique can be inferred from the gender, ethnicity, and bizygomatic width of the patient. Tables for estimating positioning in the Panoral panoramic machine have been derived from the analysis of data from 196 patients. Use of this approach eliminates the requirement for an additional submentovertex radiograph and the associated radiation dose to the patient.

Intercondylar dimension as a positioning factor for panoramic images of the temporomandibular region.

The effect of rotating the patient's head for optimum imaging of the temporomandibular region with the use of a panoramic radiographic machine with a continuous center of rotation (Panex-E) was studied. The result showed that the intercondylar distance influenced the amount of rotation necessary for that optimum image.

Comparative radiographic study of human and animal long bone patterns.

The objective of this study was to test the hypothesis that certain radiographic features can be found to distinguish between human and animal long bone fragments, and therefore would be useful as an adjunct in forensic science identification. Using proposed radiographic criteria, 13 archeologists and 12 dentists were asked to identify 20 radiographic samples as representing human or animal bone. Results showed that archeologists correctly identified 86.8% of the samples, and dentists correctly identified 81.9%. Based on the results of this study, it was concluded that radiographic interpretation of long bone fragments may be a useful aid in a forensic science investigation of human and animal remains.