Magnetic resonance imaging (MRI) on patients with temporomandibular joint disorders (TMD) has revealed that a decrease and/or increase in signal intensity from retrodiscal tissue, joint effusion (the excessive accumulation of joint fluid) and articular disc displacement are related to TMD. However, the effect of aging on these phenomena has yet to be clarified. This study was carried out to explore the relationship between changes in signal intensity from retrodiscal tissue, joint fluid status and pathological disc conditions in elderly patients with TMD. Twenty patients aged over 60 years were examined. They consisted of one man and 19 women, and ranged between 60 and 79 years in age (mean, 66.0 years). The relationships between decreased signal intensity on proton-density-weighted (PDW) images and increased signal intensity on T2-weighted (T2W) MR images from retrodiscal tissue, joint fluid status and state of articular disc were examined. Joint fluid status was classified into 5 levels by extent of high signal areas in upper and lower articular spaces on T2W images. Disc displacement status was evaluated by PDW images. The Wilcoxon test was applied for the statistical analysis. The group showing increased T2W signal intensities from the retrodiscal tissue consisted of 31 out of 40 joints (77.5%). This group showed a significant difference in comparison with the other groups in which no apparent joint fluid was shown (p<0.05). There were no statistically significant differences among other categories. The results suggest a negative relationship between joint fluid and increased signal intensity from retrodiscal tissue due to reflection of the inflammatory reaction in TM joints.

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Postgraduate clinical training for dentists in Japan became mandatory in April 2006. Mandatory postgraduate clinical training for physicians has been criticized as having accelerated the imbalance in distribution of physicians. This suggests the danger that the same phenomenon might occur in distribution of dentists. It is also necessary to investigate the geographic distribution of dental trainees and practicing dentists in Japan. In this study, the number of dental trainees enrolled in each clinical training program and number that had actually received clinical training at each facility were compared by prefecture. The results suggest that disparities in the number of dental trainees among prefectures are being compensated for by movement across prefectural borders under the clinical training facilities-group system. Postgraduate dental trainees, however, showed a significantly greater imbalance in geographic distribution than practicing dentists. Continuation of the postgraduate clinical training for dentists under the existing system may accelerate this imbalance in distribution of dentists. To prevent this, practical measures should be taken in accordance with the coming review of the system, based on research regarding changes in geographic distribution of dental trainees.

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In this study, we investigated how method of mandibular fixation influenced longterm postoperative stability of the maxilla in Class III cases. In particular, we investigated change in the maxillary occlusal plane after Occlusal Plane Alteration. Therefore, we focused on change in the palatal plane to evaluate stability of the maxillary occlusal plane, as the position of the palatal plane affects the maxillary occlusal plane. This study included 16 patients diagnosed with mandibular protrusion. Alteration of the occlusal plane was achieved by clockwise rotation of the maxilla by Le Fort I osteotomy and mandibular setback was performed by bilateral sagittal split ramus osteotomy. We analyzed and examined lateral cephalometric radiographs taken at 1 month, 3 months, 6 months, and 1 year after surgery. Stability achieved by two methods of mandibular fixation was compared. In one group of patients (group S) titanium screws were used, and in the other group (group P) titanium-locking mini-plates were used. No significant displacement was recognized in group S, whereas an approximately 0.7mm upward vertical displacement was recognized in the anterior nasal spine in group P. As a result, not only the angle of the palatal plane and S-N plane, but also occlusal plane angle in group P showed a greater decrease than that in group S. The results suggest that fixing the mandible with screws yielded greater stability of the maxilla and maxillary occlusal plane than fixing the mandible with titanium plates.

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Several studies have reported tissue blood flow and tissue oxygen tension during anesthesia, whereas there are few reports that discuss the relationship between tissue blood flow and tissue oxygen tension. The goal of this study was to investigate the relationship between these two variables before and after stellate ganglion block (SGB). We utilized 8 male Japan White rabbits. Anesthesia was maintained with propofol. For SGB, 0.2 ml of 1% lidocaine was injected and changes in mandibular bone marrow blood flow (BBF) and mandibular bone marrow oxygen tension (PbO₂) were observed (Group B). After the observed variables completely recovered, 0.2 ml of 1% lidocaine was again injected and changes in masseter muscle blood flow (MBF) and masseter muscle oxygen tension (PmO₂) were observed (Group M). The observed variables were hemodynamic parameters, common carotid artery blood flow, L (left side)-BBF, R (right side)-BBF, L-PbO₂, R-PbO₂, L-MBF, R-MBF, L-PmO₂ and R-PmO₂. In both groups, positive correlations (r=0.99; y=0.68x - 3.49 in Group B and r=0.99; y=0.62x + 0.47 in Group M) were observed when tissue blood flow was set at the X-axis and tissue oxygen tension at the Y-axis. In contrast, when tissue blood flow was set at the Y-axis and tissue oxygen tension at the X-axis, two regression lines almost overlapped (y=1.47x + 5.12 in Group B and y=1.59x - 0.28 in Group M). Therefore, it is estimated that tissue blood flow increases by approximately 15 ml/min/100g when tissue oxygen tension increases by 10 mmHg. In conclusion, there is a positive correlation between tissue blood flow and tissue oxygen tension. Changes in tissue oxygen tension should reflect the increase or decrease in tissue blood flow.

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Here, we present a case report on prosthetic reconstruction of posterior teeth and composite resin restoration of anterior teeth yielding considerable esthetic improvement, reestablishment of disocclusion guides and function.

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Various periodontal plastic surgical techniques are employed in obtaining root coverage. Recently, the use of an enamel matrix derivative (EMD) has been reported in such treatment. We report 2 cases of root coverage surgery with a coronally positioned flap in combination with EMD (CPF+EMD) and connective tissue graft in combination with EMD (CTG+EMD). Case 1: The patient was a 25-year-old woman referred to Suidobashi Hospital, Tokyo Dental College for root coverage surgery on the lower right first premolar. Gingival recession was classified as Miller Class II, as no alveolar bone loss or loss of attachment was observed in the interdental area, although recession had progressed to the mucogingival junction. The patient was diagnosed with local gingival recession caused by excessive tooth brushing. Primary conservative treatment failed to reduce the gingival recession. Subsequently, root coverage surgery with CPF+EMD was carried out. As observation at the 1-year follow-up revealed complete root coverage and no recurrence of root exposure or subjective symptoms, the postoperative course was considered to be favorable. Case 2: The patient was a 39-year-old woman referred to Suidobashi Hospital, Tokyo Dental College for root coverage surgery on the lower left canine. Gingival recession was classified as Miller Class II. Root coverage surgery with CTG+EMD was carried out. As observation at the 2-month follow-up revealed complete root coverage and no recurrence of root exposure, the postoperative course was considered to be favorable. These 2 cases indicate the effectiveness of root coverage surgery with CPF+EMD and CTG+EMD.

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