Hidemichi Yuasa

Natural Course of Untreated Symptomatic Temporomandibular Joint Disc Displacement without Reduction

In some patients with disc displacement without reduction, the symptoms of pain and decreased range of motion have been observed to resolve spontaneously over time without treatment. The natural history of this condition, however, is not well-understood. Thus, to study the natural course of disc displacement without reduction, we followed 40 patients without treatment for a period of 2.5 years. The diagnosis was established by history and physical examination and confirmed with magnetic resonance (MR) imaging. After 2.5 years, 43% of the patients were asymptomatic, 33% had decreased symptoms, and 25% of the patients showed no improvement or had required treatment. MR evidence of osteoarthritis and advanced stages of internal derangement at the initial evaluation was associated with a poor prognosis. The result of this prospective cohort study indicated that approximately 40% of patients with symptomatic disc displacement without reduction will be free of symptoms within 2.5 years, one-third will improve, whereas one-quarter will continue to be symptomatic. This knowledge should be valuable for the treatment planning and evaluation of prognosis of patients with non-reducing symptomatic disc displacement.

Clinical evaluations of coronectomy (intentional partial odontectomy) for mandibular third molars using dental computed tomography: a case-control study.

PURPOSE Studies have suggested that coronectomy reduces the risk of inferior alveolar nerve injury (IANI) when a close relationship with the inferior alveolar canal is indicated on panoramic imaging. However, the relationship between the inferior alveolar canal and the root are unclear on panoramic imaging. Our aim was to compare coronectomy with traditional extraction for the treatment of mandibular third molars that had clear high IANI risks as evaluated by dental computed tomography. PATIENTS AND METHODS We designed a case-control study of subjects with high-risk signs of IANI on panoramic images evaluated by dental computed tomography before enrollment. The 220 patients enrolled were assigned to extraction (control group, n = 118) or coronectomy (case group, n = 102). RESULTS The mean follow-up time was 13 months in the extraction group and 13.5 months in the coronectomy group. Six IANIs (5%) were found in the extraction group. In the coronectomy group, 1 patient (1%) had symptoms of neurapraxia, which disappeared within 1 month. Four remaining roots had signs of postoperative infection, and the patients underwent extraction of the root. No nerve damage resulted in these patients after repeat extraction. CONCLUSIONS Coronectomy might reduce the risk of nerve injury for patients at true high risk of IANI as evaluated by dental computed tomography. A long-term postoperative review is needed to assess the incidence of root migration and the root extraction and infection rates after coronectomy.

Serum antioxidant micronutrients and the risk of oral leukoplakia among Japanese

A population-based case-control study was designed for the investigation of any association between serum micronutrient levels and oral leukoplakia. Out of a total of 9536 subjects over the age of 40 years who participated in the oral mucosal screening programme in Tokoname city, 48 cases detected with oral leukoplakia (38 male:10 female) were recruited. For each case, four controls matched by age and sex were selected from the same cohort. We examined the fasting serum levels of retinol, alpha-tocopherol, zeaxanthin and lutein, cryptoxanthin, lycopene and carotenoids (alpha-carotene and beta-carotene) by high-performance liquid chromatography. Among males with leukoplakia mean serum lycopene and beta-carotene levels (0.175+/-0.202, 0.357+/-0.295 micromol/l) were significantly lower than those of controls (0.257+/-0.252, 0.555+/-0.408 micromol/l) (P<0.05, P<0.005). Logistic regression analysis with leukoplakia as the dependent variable showed that high serum levels of beta-carotene were related to low risk of oral leukoplakia (odds ratio 0.160, 95% C.I.: 0.029-0.866, P<0.05). There were no significant differences in any of the serum nutrients estimated in female subjects. Our results suggest for the first time that high serum levels of beta-carotene may provide protection against oral precancer for the Japanese male.

Observer agreement in the detection of proximal caries with direct digital intraoral radiography.

OBJECTIVE The aim of this study was to compare several values for consistency obtained by charged-coupled-device-based direct digital intraoral radiography with those obtained by conventional film-based radiography to evaluate observer agreement in determining the depth of proximal caries. STUDY DESIGN A total of 93 proximal surfaces on radiologic images that were obtained by both the conventional film-based bite-wing technique and by direct digital intraoral radiography were evaluated by six observers. One of these observers also evaluated the same images six months after the initial evaluation. The kappa value, consistency ratio, agreement ratio, and Kendalls correlation coefficient were calculated for interobserver and intraobserver agreement. RESULTS The overall kappa values for interobserver agreement were 0.439 and 0.424 in the direct digital system and the film-based radiography, respectively. The depth-related change of the values showed similar patterns in the two modalities for both interobserver and intraobserver agreement. CONCLUSION The digital intraoral system resulted in no deterioration in observer agreement, and it presents no problems for clinical use with respect to the reliability of diagnosis.

High-frequency color Doppler sonography of the submandibular gland: Relationship between salivary secretion and blood flow

OBJECTIVE The purpose of this study was to evaluate the changes of blood flow of the submandibular gland in comparison with salivary secretion after gustatory stimulation through use of color Doppler sonography. STUDY DESIGN High-frequency color Doppler sonography was performed on 30 healthy volunteers, aged 22 to 31 years. The prestimulation and poststimulation arterial blood flows were evaluated with color Doppler sonography and spectral analysis. RESULTS The means of prestimulation maximum and minimum velocities and pulsatility index of the submandibular gland were 6.35 +/- 2.57 cm/sec, 1.79 +/- 0.93 cm/sec, and 1.53 +/- 0.42, respectively. After the stimulation, the color signals and velocities increased and the pulsatility index decreased. There was a close correlation between the increase in minimum velocity and that of salivary secretion. CONCLUSION Color Doppler sonography is useful in analyzing changes in the blood flow of the submandibular gland caused by gustatory stimulation.

External validity of a randomised clinical trial of temporomandibular disorders: analysis of the patients who refused to participate in research

PURPOSE To assess the external validity of a randomised clinical trial (RCT) of a painful condition. METHOD Consecutive patients with painful temporomandibular disorders (TMDs) were invited to participate in a clinical trial. Patients who refused to participate were compared to those who agreed to participate in this study with respect to degree of symptoms at time of presentation. RESULTS The patients who refused to participate had more pain, and their condition interfered more with their daily life than those who accepted the invitation to participate. CONCLUSION Selection bias in RCTs of painful conditions can skew the results, and external validity should be analysed before the results are generalised.

Joint Photographic Experts Group compression of intraoral radiographs for image transmission on the World Wide Web

OBJECTIVE The purpose of this study was to evaluate the subjective quality of Joint Photographic Experts Group (JPEG) compressed images of intraoral radiographs with file sizes of 30 kilobytes or less, which can be transmitted quickly on the World Wide Web. STUDY DESIGN Conventional intraoral radiographs were digitized at sampling rates of 100, 200, 300, 400, and 600 dots per inch through use of a flatbed scanner and saved in JPEG format in 11 compression degrees. Fifty-five combinations of sampling rate and compression degree were evaluated by means of a visual analog scale. Sampling rate and compression degree combinations whose quality was inferior to that of an average image were excluded. The quality of the remaining combinations was subsequently evaluated through assessment of 8 anatomical features in each image. RESULTS Forty of the 55 combinations provided a file size less than 30 kilobytes. Thirty combinations obtained VAS scores of 0 or higher on the standardized VAS. As a result, 16 combinations of sampling and compression conditions were selected for the second part of the study. Only one combination of sampling rate and compression degree was found to provide sufficient image quality for all 8 anatomical features. CONCLUSIONS Under the file size limit of the study design, the full-sized compressed image of an intraoral radiograph did not always provide sufficient quality. This problem will be reduced by improvements in telecommunications infrastructure, which will permit faster transfer of files of larger size.

In Vitro Comparison of Subjective Image Quality of the Pana Digital Intraoral X-Ray Imaging System and Conventional Intraoral Radiography in Caries Detection

The aim of this study was to evaluate observer performance with a charge coupled device-based intraoral X-ray imaging system, Pana Digital system, in comparison with conventional film-based radiography (Ektaspeed Plus). A total of 118 teeth mounted in plaster were radiographed using both the Pana Digital system and conventional film. The occlusal and approximal surfaces of the resultant images were evaluated by six observers in relation to the caries depth. For the verification of the caries depth, the teeth surfaces were rated histologically by two examiners according to the same rating scores used for the X-ray imaging assessment. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of the two image modalities were calculated together with Cohens kappa values. No significant difference was found in any diagnostic parameters at any thresholds between the two modalities. The Kappa values for the Pana Digital system showed relatively lower levels than those of conventional film in occlusal caries assessment, whereas no apparent differences were found between the two modalities in any scores of depth for approximal caries assessment. The results of the present study, in which there was no discrepancy in diagnostic abilities, suggested that the Pana Digital system could play a useful role in clinical caries diagnosis.

Primary Treatment for Osteoarthritis of the Temporomandibular Joint by Combination Therapy of Arthrocentesis, Mouth Opening Exercises, and a Non-steroidal Anti-inflammatory Drug Regimen

Abstract Purpose: To analyse the effect of primary treatment of osteoarthritis of the temporomandibular joint by a combination of arthrocentesis, range of motion exercises, and non-steroidal anti-inflammatory drugs for 12 weeks. Patients and Methods: Fifty patients with osteoarthritis of the temporomandibular joint and unilateral moderate or severe temporomandibular joint dysfunction underwent arthrocentesis and steroid injection followed by mouth opening exercises and oral administration of non-steroidal anti-inflammatory drugs. Therapy continued for 12 weeks, or was stopped earlier if symptoms improved. Patients were evaluated every 2 weeks by visual analogue scales for pain at rest, pain with mandibular motion, pain on chewing and interference with daily life, and measurement of maximal mouth opening. Results: All visual analogue scale values were statistically reduced and maximal mouth opening statistically increased from 32 to 40 mm with this combination therapy. The improvement rates at 2, 4, 6, and 8 weeks after the start of therapy were 46%, 62%, 70%, and 72%, respectively. However, there was no difference between the 10th and 12th weeks, which both showed 76% improvement. Conclusion: This combination therapy is an effective primary treatment for osteoarthritis of the temporomandibular joint. The follow-up period should be 10 to 12 weeks to reach maximum improvement.

Consent for Enrolment in Randomised Controlled Trials: a Questionnaire Study

Abstract Objectives: To test the hypothesis that the enrolment rate in a randomised controlled trial involving ‘malignant tumours’ would be lower than that involving ‘common illness’. Patients and Methods: Outpatients from oral and maxillofacial surgery clinics were requested to select from among the following 3 statements that which most closely reflected their attitude toward randomised controlled trials for a hypothetical common illness and a malignant tumour: “I may take part in a randomised controlled trial” (accept), “I will take part in a clinical study based on study conditions” (conditional), or “I will not take part in a randomised controlled trial” (refuse). Results: For common illness, 117 of 1083 participants (10.8%) selected ‘accept’, 664 (61.3%) selected ‘conditional’, and 302 (27.9%) selected ‘refuse’. For malignant tumours, 137 participants (12.7%) selected ‘accept’, 644 (59.5%) selected ‘conditional’, and 302 (27.9%) selected ‘refuse’. Among those who would refuse to participate in a randomised clinical trial for a common illness, 27.2% of patients selected “I will take part in a clinical study based on study conditions” or “I may take part in a randomised controlled trial” for malignant tumour. Conclusion: The hypothesis that the enrolment rate in a randomised controlled trial may be lower when patients are thought to suffer from malignant tumours than when they are thought to suffer from common illness is not justifiable.