Radiographic features associated with temporomandibular joint disorders among African, White, Chinese, Hispanic, and Indian racial groups

Context: Various radiographic features have been associated with temporomandibular joint disorders (TMDs); however, these characteristics have not been compared among different racial groups.Aims: To radiographically evaluate and compare craniofacial patterns and condylar findings suggestive of TMD among African, White, Chinese, Hispanic, and Indian racial groups.Settings and Design: This multicenter retrospective study used data from three private orthodontic practices and a University Orthodontic Clinic.Subjects and Methods: Panoramic and lateral cephalometric radiographs were collected from 250 subjects who were equally divided into five racial groups: Africans, Whites, Chinese, Hispanics, and Indians. All radiographs were initial records from patients seeking orthodontic treatment. Linear and angular cephalometric measurements were used to evaluate and compare cephalometric characteristics associated with TMD among groups. Panoramic radiographs were analyzed to compare the presence of condylar abnormalities and antegonial notching among groups.Statistical Analysis Used: One‑way analysis of variance, followed by Tukey’s test.Results: African and Chinese groups had the smallest mean cranial base measurements, while the Indians had the largest. The mean Y‑axis value was significantly larger in the Chinese group compared with the other groups. Increased mandibular plane angles were seen in the Chinese and African patients, compared with subjects from other groups. The mean percentage of condylar anomalies was higher in the Chinese subjects compared with all other groups.Conclusions: Chinese patients presented with more radiographic features suggestive of TMD, whereas the Indians showed the least, compared with subjects from the White, Black, and Hispanic racial groups.Keywords: Craniofacial patterns, ethnicities, races, temporomandibular joint disorder

The wave forms of temporomandibular joint sound clicking and crepitation

The aim of the present study was to determine the sound wave forms which correspond to auscultatory findings of temporomandibular joint (TMJ) clicking and crepitation. Such knowledge is important when selecting parts of digital recordings for spectral analysis. Electronic digital recordings were made with a sampling rate of 44 100 Hz from 60 subjects, including 51 patients referred for suspected rheumatological disease and nine healthy subjects. Accelerometers with the bandwidth 20–3600 Hz were used for all subjects and complementary recordings were made from a subgroup of nine subjects using a measurement microphone with the bandwidth 20–20 000 Hz. The clicking sounds could be classified into different types according to differences in temporal period duration ( T ) as measured on the analogue display. One type of clicking, found in 51% of the patients, had a T of 2–20 ms. Another type, found in 70% of the subjects, had a T of less than 1 ms, often as low 0.2 ms. This type of clicking was not seen at all in the analogue display if the sampling rate was below 3 000 Hz. The character of the two types of clicking differed: the short duration sounds had a very high pitch, while the pitch of the longer duration sound was lower. Crepitation was found in 63% of the subjects and was observed to be composed of a series of short duration sounds, occurring with brief (less than 10 ms) intervals. It is concluded that the accelerometer (or microphone) bandwidth should cover the entire audible range (20–20 000 Hz), and that sampling rates must be much higher than 3000 Hz, and preferably greater than 10 000 Hz, before the true significance of electronically recorded joint sounds/vibrations can be determined.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74177/1/j.1365-2842.1996.tb00810.x.pd