Dental maturation in subjects with extreme vertical facial types

The purpose of this research was to investigate whether there is a difference in dental maturation between skeletal open bite and skeletal deep bite subjects of the same chronological age. The material consisted of 40 lateral headfilms and 40 panoramic radiographs of 20 male and 20 female white subjects, with a mean chronological age of 9 years and 2 months (range: 7 years 6 months to 10 years 11 months). These subjects were selected on the basis of lower anterior face height as a percentage of total face height and on the amount of open or deep-bite from a total sample of 400 subjects. The persons exhibiting the most extreme values at both ends of the distribution were selected to create two groups with 20 subjects in each (10 males and 10 females). Thus, the groups represented subjects with either a large lower anterior face height associated with an open bite or a small lower anterior face height associated with a deep bite. A double blind determination of dental maturation, expressed by dental age, for each subject was performed on the panoramic radiographs using the system of Demirjian et al. (1973). A covariance analysis was used to eliminate variability introduced by the large age range of the sample. The skeletal open bite and deep bite groups presented mean dental ages of 120.48 and 114.00 months, respectively. Statistical analysis demonstrated that this difference was statistically significant at P < 0.05. Therefore, it seems that skeletal open bite subjects presented a slight tendency to have an advanced dental maturation, expressed by dental age, as compared with skeletal deep bite subjects.

The prevalence of disc displacement in symptomatic and asymptomatic volunteers aged 6 to 25 years

The purpose of this investigation was to determine a possible association between disc displacement and temporomandibular disorders (TMD). Fifty-six Brazilian asymptomatic volunteers (25 males and 31 females) and 181 symptomatic TMD patients (112 females and 69 males) participated. Volunteers did not have temporomandibular joint pain, limited jaw opening, joint sounds, or previous TMD treatment. Bilateral temporomandibular joint magnetic resonance imaging scans were obtained from all subjects. Joints were classified as normal or having disc displacement. Asymptomatic volunteers had 28 (25%) joints with disc displacement; 10 (18%) had unilateral and 9 (16%) had bilateral disc displacement. Of the TMD patients, 25 (13.8%) had bilateral symptomatic but normal joints. Fifty-one (28.2%) had unilateral and 105 (58%) had bilateral disc displacement. Odds ratios (12.2 [95% confidence interval = 6.1 to 24.4, P = .001]) suggest a strong association between disc displacement and TMD. This study suggests that disc displacement is relatively common (34%) in asymptomatic volunteers and is highly associated with patients (86%) with TMD.

[Effect of final washing in a small volume of water on processing of periapical radiographs]

The main goal this research was to find out the effectiveness of the final wash in periapical X-ray films. Spectrophotometry determined the residues of sodium hyposulphite taken as a positive sign for the effectiveness of wash on developed films. Three different kinds of film, two Kodak and one Agfa were used. Films were different sensibility and underwent tests. Two containers, one for the intermediate and other for the final wash were used in the first test; in the second, only one container was used for both washes. A residue of 0.4 mg of sodium hyposulphite was considered acceptable. On the three films used, the acorent of sodium hyposulphite detected was inferior to 0.4 mg in the first test, after 5 minutes exposure, nevertheless the small volume of water used. The second test showed a with range of variation in results and so it not recommend.

[Evaluation of the performance of undergraduate students in obtaining radiographs using the bisecting technique, during 1986 and 1987]

This paper shows the results obtained when two methods for teaching intrabucal periapical technique were fested. During 1986, the 3rd term students applied the suggested table for vertical angulation when taking periapical radiographs; in 1987, during 5th term, the same students used the bisecting-angle technique for the intrabucal radiographs. The comparison of both teaching methods lead to the following conclusions: The most frequent errors observed were due to technique, followed by incorrect film processing; Inadequate vertical angulation was observed mainly when the suggested tables were used; this error was reduced when bisecting-angle technique was used. errors in film mounting were negligible. The standardization of dark room procedures as well as the utilization of time-temperature method after an adequate X-ray exposure of the films were certainly responsible for the small number of errors due to film processing.

[Radiographic study of the applicability of three anatomical landmarks in transcranial radiography of the temporomandibular joint]

The variability of the angles formed between the long axis of the right and left condyles and the midsagittal plane, as well as the applicability of three anatomic landmarks--zigoma, gonion and base of the mandible, for transcranian radiographs of the TMJ were studied. The radiographic method used in this study was the HIRTZ axial projection. The results of the measurements showed a great variation in the angle formed by the long axis of the condyles and the midsagittal plane, from 48 degrees-79 degrees (x = 63.73 degrees) for the right side, from 50 degrees-80 degrees (x = 67.43 degrees) for the left side. It was also observed that the use of the three anatomic landmarks must not be generalized, being more precisely indicated for tapering head and face.