Kengo Torii

Publications of Kengo Torii

• Longitudinal course of temporomandibular joint sounds in Japanese children and adolescents.

  Authors: Kengo Torii

  Head & face medicine. 01/2011; 7:17.

  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 theMany 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. 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. 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). 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.

• Occlusal adjustment using the bite plate-induced occlusal position as a reference position for temporomandibular disorders: a pilot study.

  Authors: Kengo Torii, Ichiro Chiwata

  Head & face medicine. 03/2010; 6:5.

  Many researchers have not accepted the use of occlusal treatments for temporomandibular disorders (TMDs). However, a recent report described a discrepancy between the habitual occlusal position (HOP)Many researchers have not accepted the use of occlusal treatments for temporomandibular disorders (TMDs). However, a recent report described a discrepancy between the habitual occlusal position (HOP) and the bite plate-induced occlusal position (BPOP) and discussed the relation of this discrepancy to TMD. Therefore, the treatment outcome of evidence-based occlusal adjustments using the bite plate-induced occlusal position (BPOP) as a muscular reference position should be evaluated in patients with TMD. The BPOP was defined as the position at which a patient voluntarily closed his or her mouth while sitting in an upright posture after wearing an anterior flat bite plate for 5 minutes and then removing the plate. Twenty-one patients with TMDs underwent occlusal adjustment using the BPOP. The occlusal adjustments were continued until bilateral occlusal contacts were obtained in the BPOP. The treatment outcomes were evaluated using the subjective dysfunction index (SDI) and the Helkimo Clinical Dysfunction Index (CDI) before and after the occlusal adjustments; the changes in these two indices between the first examination and a one-year follow-up examination were then analyzed. In addition, the difference between the HOP and the BPOP was three-dimensionally measured before and after the treatment. The percentage of symptom-free patients after treatment was 86% according to the SDI and 76% according to the CDI. The changes in the two indices after treatment were significant (p < 0.001). The changes in the mean HOP-BPOP differences on the x-axis (mediolateral) and the y-axis (anteroposterior) were significant (p < 0.05), whereas the change on the z-axis (superoinferior) was not significant (p > 0.1). Although the results of the present study should be confirmed in other studies, a randomized clinical trial examining occlusal adjustments using the BPOP as a reference position appears to be warranted.

• A case report of the symptom-relieving action of an anterior flat plane bite plate for temporomandibular disorder.

  Authors: Kengo Torii, Ichiro Chiwata

  The open dentistry journal. 01/2010; 4:218-22.

  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 aSplint 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. CASE PRESENTATION: Anterior bite plate treatment was started in a patient complaining of arthralgia. A discrepancy between the HOP and BPOP values was recorded three days after the first visit; this discrepancy disappeared on day 6, and the disappearance was maintained between days 6 and 12. The disappearance was associated with a decrease in the severity of the patient's symptoms; however, the discrepancy reappeared after 15 days, coinciding with the complete disappearance of the patient's symptoms. Therefore, the effect of the bite plate on the resolution of the discrepancy between the HOP and BPOP values was interpreted as being unsustainable and occlusal equilibration for the BPOP was performed at 17 days. Thereafter, neither a discrepancy in the HOP and BPOP values nor any symptoms of TMD (right temporomandibular joint pain or limited jaw opening) reoccurred during a two-year follow-up period. CONCLUSION: Within the limitations of the present study, the symptom-relieving action of an anterior flat plane bite plate on the resolution of occlusal discrepancy appeared to be temporary. This outcome supports previously reported conclusions that the effectiveness of stabilization splint therapy for reducing symptoms in patients with pain dysfunction syndrome does not differ significantly from that of other conservative therapies or of no treatment at all.

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

  Authors: Kengo Torii, Ichiro Chiwata

  Journal of medical case reports. 01/2007; 1:85.

  ABSTRACT: BACKGROUND: Although the discrepancy between the habitual occlusal position (HOP) and the flat bite plate-induced occlusal position (BPOP) (regarded as the muscular physiological referenceABSTRACT: BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

• Relationship between habitual occlusal position and flat bite plane induced occlusal position in volunteers with and without temporomandibular joint sounds.

  Authors: Kengo Torii, Ichiro Chiwata

  Cranio : the journal of craniomandibular practice. 02/2005; 23(1):16-21.

  The aim of this study was to assess whether temporomandibular joint (TMJ) sounds are associated with the difference between the habitual occlusal position (HOP) and the bite plane induced occlusalThe aim of this study was to assess whether temporomandibular joint (TMJ) sounds are associated with the difference between the habitual occlusal position (HOP) and the bite plane induced occlusal position (BPOP). Fifteen dental technician school students who had complete natural dentition, normal occlusion and who exhibited TMJ sounds were compared with fifteen healthy control subjects. HOP was recorded by voluntary jaw closing while in an upright position, and BPOP was recorded after wearing an anterior bite plane for a short period of time. Three interocclusal records were obtained in both positions with a vinyl polysiloxane material, and the recorded maxillomandibular relations were analyzed three-dimensionally and compared. Subjects with TMJ sounds had statistically larger differences between HOP and BPOP than controls (p<.05). Within this study population, an association was found between TMJ sounds and the difference between HOP and BPOP.