Haruyasu Tanabe

Cause of early skeletal relapse after mandibular setback

The present study was undertaken to examine the factors that might be responsible for the skeletal relapse occurring during the period of intermaxillary fixation after mandibular setback osteotomy. Fifteen patients, treated for absolute mandibular prognathism by modified sagittal split ramus osteotomy and fixation by skeletal suspension wiring, were evaluated cephalometrically by reference to the degree of postsurgical superior shift of the gonial region of the distal segment as a parameter of relapse since such a shift was evident despite the use of wiring. It was found that the degree of inadvertent anteroposterior rotation of the proximal segment at surgery, rather than the extent and pattern of surgical repositioning of the distal segment, was significantly correlated with the degree of shift. This result emphasizes the justification of preserving the proximal segment in its exact original anatomic site, in addition to the use of skeletal fixation, to ensure predictable stability after mandibular setback osteotomy.

Dynamic multislice helical CT of ameloblastoma and odontogenic keratocyst: Correlation between contrast enhancement and angiogenesis

Purpose The purpose of this study was to assess whether the enhancement characteristics of dynamic multislice helical CT (MS-CT) could help in the differential diagnosis of ameloblastomas and odontogenic keratocysts. The correlation between enhancement characteristics and immunohistochemical findings, especially with regard to angiogenesis, was also evaluated. Method Dynamic MS-CT was performed in 13 consecutive patients (8 ameloblastoma cases and 5 odontogenic keratocyst cases). The percentage of density increase (Enh%) was measured in dynamic MS-CT images taken during the arterial phase, and microvessel density (MVD) was analyzed using immunohistochemical study with anti-CD31 antibody. The Mann–Whitney U test was used to evaluate the significance of the Enh% or the MVD values between lesion subtypes, and the Spearman correlation coefficient was used to evaluate the correlation between the Enh% and the MVD in ameloblastomas and odontogenic keratocysts. Results The Enh% in ameloblastomas was significantly higher than that of odontogenic keratocysts (P < 0.005). The MVD of ameloblastomas was also significantly higher than that of odontogenic keratocysts (P < 0.005). The Enh% values for ameloblastomas and odontogenic keratocysts were positively correlated with the respective MVD values (r = 0.92, P ≤ 0.000). Conclusion Dynamic MS-CT is useful tool for differentiating between ameloblastomas and odontogenic keratocysts on the basis of the contrast enhancement values of intratumoral vascularities during the arterial phase. Furthermore, the Enh% obtained by dynamic MS-CT is correlated with the MVD in ameloblastomas and odontogenic keratocysts.

Skeletal fixation versus skeletal relapse

The use of skeletal fixation was evaluated for skeletal stability during the period of intermaxillary fixation following a modified sagittal split ramus osteotomy for mandibular prognathism. A combination of bilateral maxillary peralveolar wires and circummandibular wires in the canine region was used for the fixation. One group of patients with this method of fixation (S group) and a second group without the fixation (C group) were compared cephalometrically. Statistically significant differences existed in the amount and pattern of relapse; the fixation produced a significant effect on retention of the corrected chin position. As a consequence, downward and backward rotation of the distal fragment of the mandible and compensatory incisor extrusion were notably controlled. However, upward shift of the posterior end of the distal fragment occurred persistently even in the S group, causing considerable intrusion of the posterior teeth in comparison with the C group. This seems to indicate that tension, probably exerted by the pterygomasseteric sling, is important in postoperative skeletal instability.

Dangerous angles and depths for middle ear and middle cranial fossa injury during arthroscopy of the temporomandibular joint

PURPOSE Several reports have suggested a risk of injury to the middle cranial fossa and middle ear during arthroscopic procedures in the superior joint space of the temporomandibular joint (TMJ). However, there has been no anatomic study of directions and distances of the TMJ from the posterior portal in relation to the risk of mandibular fossa injury. In this study, the angles and depths at which the risk is greatest for injury to the deepest point of the mandibular fossa (DP) and to the middle ear during arthroscopy were analyzed. MATERIALS AND METHODS Three-dimensional measurements of 96 mandibular fossae in 48 dry skulls were made. RESULTS It was found that the distance from the lateral rim of the fossa to DP and Hugiers canal was 9.50 +/- 2.07 mm and 17.04 +/- 3.09 mm, respectively. The most dangerous angle for DP injury in the Frankfort horizontal plane (FH plane) was an inclination of the instrument base of -8 degrees dorsad and 17 and 19 degrees caudad in the frontal plane. The most dangerous angle for Hugiers canal injury was a tilting of the instrument base of 15 degrees ventrad in the FH plane and -2 degrees craniad in the frontal plane. However, these values showed a wide range. CONCLUSION It was concluded that great care must be exercised in manipulation of instruments near the DP and Hugiers canal to avoid injury to the middle ear or penetration into the middle cranial fossa.

Morphologic study of the mandibular fossa and the eminence of the temporomandibular joint in relation to the facial structures

To clarify the relationship between the temporal component of the temporomandibular joint and facial bone structure, we measured anthropologic craniometric points and the structure of the mandibular fossa, including the eminence in 33 Japanese male dry skulls, with a three-dimensional apparatus. The length from the articular tubercle to the medial glenoid tubercle is correlated with skeletal variables such as the length of the fossae, the width of the masseter origin, and the mandibular length. Therefore it appears that the frontal dimension is related to the facial development, which is attributable to bite force. Goniometrically, the angle between the line deepest point of the fossa--the midpoint of the eminence and the Frankfort horizontal plane (middle angle)--was negatively correlated only with the ANB angle, suggesting that a steeper middle angle of the eminence is related to a retrusive maxilla or protrusive mandible.

μ-Opioid receptor mRNA expression and immunohistochemical localization in the rat temporomandibular joint

This study was undertaken to examine the presence and distribution of the mu-opioid receptor (MOR) in the non-inflamed rat temporomandibular joint (TMJ) using non-radiographic in situ hybridization at the mRNA level and immunohistochemistry at the protein level. MOR mRNA and MOR-like immunoreactivity (MOR-LI) were found around the small blood vessels in the anterior part of the synovial membrane. The number of MOR mRNA signals in the anterior synovial membrane was significantly higher than that in the posterior part. Morphologically, MOR mRNA and MOR-LI were localized in amorphous materials considered to be nervous tissue, as well as some cell types considered to be macrophages, mast cells and endothelial cells. The present study showed the distribution of MOR in the rat TMJ synovial membrane and suggests that the opiate system plays an important role in endogenous analgesia in the TMJ.

The number of microvascular complications is associated with an increased risk for severity of periodontitis in type 2 diabetes patients: Results of a multicenter hospital-based cross-sectional study

To explore the relationships between periodontitis and microvascular complications as well as glycemic control in type 2 diabetes patients.

Localised Amyloidosis of the Palate: Multislice Helical Computed Tomography and Magnetic Resonance Imaging Findings

Abstract Localised amyloidosis in the head and neck is a rare disease. This report presents a 43-year-old woman with localised amyloidosis of the hard palate. Multislice helical computed tomography and magnetic resonance imaging findings are discussed. Computed tomography findings are non-specific with various degrees of contrast enhancement resulting from the degree of vascularity in the lesion. Signal intensities on both T1 and T2-weighted magnetic resonance images resemble those of skeletal muscle, and significant enhancement on enhanced T1-weighted magnetic resonance imaging is noted.