Longitudinal course of temporomandibular joint sounds in Japanese children and adolescents

Abstract Background Many epidemiological studies of temporomandibular disorders (TMDs) in children and adolescents have been performed. However, the results of such studies have varied, and a comprehensive view of the prevalence and severity of symptoms and signs is difficult to obtain. In the present study, temporomandibular joint (TMJ) sounds, which are the most common signs and symptoms of TMD, were observed longitudinally, and the need for treatment was evaluated. Methods Seventy individuals in six age groups (5, 6, 7, 8, 9, and 10 years old at the beginning of the observation period) participated in an epidemiological investigation conducted between 1987 and 1992. During each clinical examination, the following parameters were examined: maximum unassisted jaw opening, TMJ clicking, and the coincidence or difference between the midlines of the upper central incisors and the lower central incisors. In addition, the bilateral bite force was recorded, and the numbers of erupted, decayed, and filled teeth were recorded. Results Eight individuals dropped out because they moved. No TMJ dysfunction requiring treatment was observed in this series. TMJ clicking was observed in 30 subjects (48%); however, this symptom was temporary in most of subjects (26 subjects; 42%), and only 3 subjects (5%) had persistent clicking (continuing until the end of the observation period). The incidences of clicking were not significantly different among the six groups (x2 = 4.265). Clicking was significantly more common among girls (19 subjects) than among boys (11 subjects; P = 0.042). A significantly lower bite force (17 ± 18 kg) was recorded for the subjects with persistent clicking, compared with that of the other subjects (8- and 9-year-olds; mixed dentition) without persistent clicking (32 ± 17 kg). The persistent clicking began at an age of 11 or 12 years (permanent dentition). Conclusion Most of the clicking observed in the children and adolescents was temporary, and no difference in the incidence of clicking was observed among the six age groups. Girls had a significantly higher incidence of clicking than boys.</p

Occlusal management for a patient with aural symptoms of unknown etiology: a case report

<p>Abstract</p> <p>Background</p> <p>Although the discrepancy between the habitual occlusal position (HOP) and the flat bite plate-induced occlusal position (BPOP) (regarded as the muscular physiological reference position) has been recently reported to be related to symptoms of temporomandibular disorders (TMDs), it still remains unclear whether the occlusal equilibration in the reference position is effective to resolve TMD-related discrepancy and symptoms. Aural symptoms (otalgia, tinnitus, vertigo et cetera) have been included under TMD symptoms.</p> <p>Methods</p> <p>To examine the effect of occlusal equilibration for the treatment of TMDs, occlusal equilibration was performed for a patient with aural symptoms (otalgia, tinnitus and vertigo) of unknown etiology in the right ear. An occlusal analysis was performed on this patient with dental models mounted on an articulator after relieving painful symptoms by an appliance therapy and a discrepancy was identified (p < 0.005). Occlusal equilibration in the BPOP was then performed for the patient by selective tooth grinding, because it was estimated that the interocclusal space between upper and lower occlusal surfaces would be rectified by selective grinding.</p> <p>Results</p> <p>At completion of treatment, the discrepancy was not significant (p > 0.25), and the patient's right condyle had shifted 2.8 mm posteromedially in the horizontal plane, and the left condyle had shifted 1.0 mm laterally in the voluntarily closed position from the previous HOP. The aural symptoms of the patient were resolved, and there has been no recurrence to date after a two-year follow-up period.</p> <p>Conclusion</p> <p>An occlusal analysis should be performed in patients exhibiting TMD symptoms to identify the presence or absence of any discrepancy between the HOP and the BPOP. If a discrepancy exists, occlusal equilibration should be attempted in the reference position.</p

A Case Report of the Symptom-Relieving Action of an Anterior Flat Plane Bite Plate for Temporomandibular Disorder

Splint therapy is a widely used modality for temporomandibular disorders (TMDs). However, questions remain regarding the mechanism of symptom relief. Recently, a relation between TMD and a discrepancy between the habitual occlusal position (HOP) and the anterior flat plane bite plate-induced occlusal position (BPOP) has been reported. Therefore, to understand the mechanism of the symptom relief associated with the use of a bite plate, the changes in both the HOP and BPOP values were observed during anterior bite plate treatment in a patient with TMD

Properties of star formation of the Large Magellanic Cloud as probed by young stellar objects

We perform a systematic study of evolutionary stages and stellar masses of young stellar objects (YSOs) in the Large Magellanic Cloud (LMC) to investigate properties of star formation of the galaxy. There are 4825 sources in our YSO sample, which are constructed by combining the previous studies identifying YSOs in the LMC. Spectral energy distributions of the YSOs from optical to infrared wavelengths were fitted with a model consisting of stellar, polycyclic aromatic hydrocarbon and dust emissions. We utilize the stellar-to-dust luminosity ratios thus derived to study the evolutionary stages of the sources; younger YSOs are expected to show lower stellar-to-dust luminosity ratios. We find that most of the YSOs are associated with the interstellar gas across the galaxy, which are younger with more gases, suggesting that more recent star formation is associated with larger amounts of the interstellar medium (ISM). N157 shows a hint of higher stellar-to-dust luminosity ratios between active star-forming regions in the LMC, suggesting that recent star formation in N157 is possibly in later evolutionary stages. We also find that the stellar mass function tends to be bottom-heavy in supergiant shells (SGSs), indicating that gas compression by SGSs may be ineffective in compressing the ISM enough to trigger massive star formation. There is no significant difference in the stellar mass function between YSOs likely associated with the interface between colliding SGSs and those with a single SGS, suggesting that gas compression by collisions between SGSs may also be ineffective for massive star formation.Comment: 26 pages, 16 figures, accepted for publication in Ap