Tomoaki Shibuya

Arthroscopic removal of nodules of synovial chondromatosis of the temporomandibular joint.

ABSTRACT In this report we describe a new method for removing nodules of TMJ synovial chondromatosis using arthroscopic surgery instead of open surgery. We used two steps during arthroscopy. In the first, we lavaged the cavity with sterile saline. In the next step, the second cannula was replaced with ethmoid forceps. Under arthroscopic guidance through the first cannula, all loose bodies were removed using the forceps. Since the loose bodies are not fragmented during this procedure, the time needed for removal is shortened. Based on this experience, we suggest the use of ethmoid forceps should be considered as an alternative procedure when nodules are unable to pass through the cannula by lavage with sterile saline.

Synovial Chondromatosis of the Left Temporomandibular Joint Superficially Resembling Chondrosarcoma: A Case Report

ABSTRACT A 25 year-old woman was referred to the clinic complaining of pain in the left temporomandibular joint (TMJ) and trismus. According to the x-ray images, a solitary mass was observed in the anterior pouch of the lower joint cavity. The mass was removed by means of a synovectomy and a diskectomy. Upon light microscopic examination, the tissue removed showed high cellular activity. As a differential diagnosis, we had to consider the possibility of chondrosarcoma based on the histopathological features; however, since no invasive nor metastatic finding was recognized, we made a diagnosis of synovial chondromatosis despite its rare existence. Although there has been no sign of recurrence at present, we plan to carefully follow up with the patient.

Diagnosis of occlusal dysesthesia utilizing prefrontal hemodynamic activity with slight occlusal interference

Clinical diagnosis of occlusal dysesthesia (OD), also referred to as phantom bite syndrome, is currently based on the absence of objective occlusal discrepancy despite the persistent complaint of uncomfortable bite sensation. We previously demonstrated that the subjective feeling of occlusal discomfort generated by artificial occlusal interference can be objectively evaluated using prefrontal hemodynamic activity in young healthy individuals. The aim of this study was to investigate whether dental patients with and without OD show distinct prefrontal activity during grinding behavior with an occlusal interference. Six dental patients with OD (OD group) and eight patients without OD (control group) grinded piled occlusal strips placed between their first molars and reported their perception and discomfort thresholds during continuous monitoring of prefrontal hemodynamic activity with a portable functional near‐infrared spectroscopy. Although patients without OD showed the typical hemodynamic pattern of increased oxyhemoglobin and reduced deoxyhemoglobin (HHb) concentration, those with OD showed persistent incremental increases of HHb concentration that began at the loading of occlusal strips on their molars before they executed grinding. The intensities of the task‐related HHb activities showed statistically significant differences between OD and control groups, particularly at channel 3, arranged over the left frontal pole cortex. When the discrimination criterion was set using the intensity values of channel 3 from both groups, the overall accuracy of the OD discrimination was 92.9%. Although physiological interpretation has yet to be elucidated, the task‐related response of an increase in HHb may be a useful neuronal signature to characterize dental patients with OD.

Prefrontal Hemodynamic Changes Associated with Subjective Sense of Occlusal Discomfort

We used functional near-infrared spectroscopy to measure prefrontal brain activity accompanying the physical sensation of oral discomfort that arose when healthy young-adult volunteers performed a grinding motion with mild occlusal elevation (96 μm). We simultaneously evaluated various forms of occlusal discomfort using the visual analogue scale (VAS) and hemodynamic responses to identify the specific prefrontal activity that occurs with increased occlusal discomfort. The Oxy-Hb responses of selected channels in the bilateral frontopolar and dorsolateral prefrontal cortices increased in participants who reported increased severity of occlusal discomfort, while they decreased in those who reported no change or decreased occlusal discomfort during grinding. Moreover, the cumulative values of Oxy-Hb response in some of these channels were statistically significant predictive factors for the VAS scores. A generalized linear model analysis of Oxy-Hb signals in a group of participants who reported increased discomfort further indicated significant cerebral activation in the right frontopolar and dorsolateral prefrontal cortices that overlapped with the results of correlation analyses. Our results suggest that the increased hemodynamic responses in the prefrontal area reflect the top-down control of attention and/or self-regulation against the uncomfortable somatosensory input, which could be a possible marker to detect the subjective sense of occlusal discomfort.

Instrument for lateral release in temporomandibular joint hypomobility

mandibular joint (TMJ) by Ohnishi,1 intervention by arthroscopic examination and surgery have become popular worldwide for treating TMJ disorders. The investigators of many studies have reported that arthroscopic sweep, lysis, and lavage improve joint function and relieve the pain caused by persistent closed lock of the TMJ.2 There are a few reports of lateral release and stretching of the capsule. Ohnishi1 was the first to report the use of arthroscopy to show adhesive tissue in the lateral region of the upper joint cavity. Murakami et al3 and Moses and Poker4 suggested the importance of the capsular stretch procedure or capsular release for joint mobility. Although previous reports suggested that lateral lysis and stretching of the lateral capsule

Use of a new instrument for lateral release in arthroscopic surgery of the temporomandibular joint: a preliminary study.

We developed a new instrument, which we call a lateral releaser, to improve the safety of either a blind lateral release or lateral stretching within the TMJ We used it during arthroscopic surgery in patients with chronic painful hypomobility of the temporomandibular joint (TMJ). We operated on 24 TMJs in 17 patients (15 women and 2 men). At operation, the mean increase in the interincisal distance was 22 mm (range 10-32). No instruments were broken. No serious surgical complications were reported during or after operation. Many of the patients currently have an interincisal distance exceeding 38 mm.