Masashi Sugisaki

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.

Randomized Clinical Trial of Treatment for TMJ Disc Displacement

Of the various conservative treatment modalities available for temporomandibular disorders, we believe that therapeutic exercise has a good prognosis, especially for anterior disc displacement without reduction. Since its effectiveness has not been extensively evaluated, we conducted a comparative study to verify the hypothesis that treatment efficacy would not differ for exercise and occlusal splints. Fifty-two individuals with anterior disc displacement without reduction were randomly assigned to a splint or a joint mobilization self-exercise treatment group. Four outcome variables were evaluated: (i) maximum mouth-opening range without and (ii) with pain, (iii) current maximum daily pain intensity, and (iv) limitation of daily functions. All outcome variables significantly improved after 8 weeks of treatment in both groups. In particular, the mouth opening range increased more in the exercise group than in the splint group. This result demonstrates that therapeutic exercise brings earlier recovery of jaw function compared with splints.

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.

Influence of Psychosocial Factors and Habitual Behavior in Temporomandibular Disorder–Related Symptoms in a Working Population in Japan

Background: The symptoms of temporomandibular disorders (TMD) are directly influenced by numerous factors, and it is thought that additional factors exert indirect influences. However, the relationships between TMD-related symptoms (TRS) and these contributing factors are largely unknown. Thus, the goal of the present study was to investigate influences on TRS in a working population by determining the prevalence of TRS, analyzing contributing factors, and determining their relative influences on TRS. Materials and Methods: The study subjects were 2203 adults who worked for a single company. Subjects completed a questionnaire assessing TRS, psychosocial factors (stress, anxiety, depressed mood, and chronic fatigue), tooth-contacting habit, and sleep bruxism-related morning symptoms, using a 5-point numeric rating scale. Our analysis proceeded in 2 phases. First, all variables of the descriptor were divided into parts by using an exploratory factor analysis. Second, this factorial structure was verified by using a confirmatory factor analysis with structural equation modeling. Results: Of 2203 employees, 362 reported experiencing TRS (16.4%). Structural equation modeling generated a final model with a goodness of fit index of 0.991, an adjusted goodness of fit index of 0.984, and a root mean square error of approximately 0.021. These indices indicate a strong structural model. The standardized path coefficients for “habitual behavioral factors and TRS,” “psychosocial factors and habitual behavioral factors,” “psychosocial factors and TRS,” and “gender and habitual behavior factors” were 0.48, 0.38, 0.14, and 0.18, respectively. Conclusions: Habitual behavioral factors exert a stronger effect on TRS than do psychosocial factors.

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.

Ectopic pneumosinus maxillaris dilatans. A case report.

An abnormal topical expansil condition of the paranasal sinuses due to dyspneumatizing development is called pneumosinus dilatans. A recent case of pneumosinus maxillaris dilatans causing an apparent alveolar swelling is reported in this paper. No such case has previously been described to our knowledge.

Changes in the lingual muscles of obese rats induced by high-fat diet feeding.

OBJECTIVE To elucidate the influences of obesity on the properties and volume of lingual (genioglossus and geniohyoid) muscles in obese rats. METHODS We analysed the accumulation of triacylglycerol and the diameter of myofibres in the lingual muscles using histochemistry, and the MyHC composition using real-time PCR in rats fed a high-fat diet for 10 weeks. In the genioglossus and geniohyoid muscles, the percentage of oil droplet areas in the obesity group were 3.6 and 2.5 times greater than those in the control group, respectively (p<0.025). The diameters of the slow myofibres in the genioglossus and geniohyoid muscles were approximately 20% greater in the obesity group than in the control group (p<0.0001), while that of the fast myofibres in the geniohyoid muscle was approximately 10% greater in the obesity group than in the control group (p<0.0001). No significant difference in the expressions of any of the MyHC isoforms studied was found in any of the muscles studied between the obesity and control groups. CONCLUSION High-fat diet feeding induced the fat deposition in the myofibre and influenced the structure of the lingual (genioglossus and geniohyoid) muscles.

A survey of influence of work environment on temporomandibular disorders-related symptoms in Japan

IntroductionThis study aimed at identifying the factors that influence the incidence of temporomandibular disorders (TMD)-related symptoms (TRS) in a Japanese working population.MethodsOur study subjects comprised of 1,969 employees from the same Japanese company. The subjects were assessed using a questionnaire that covered both TRS and the work environment. TRS were measured from 4 items on the questionnaire. The work environment factors recorded were the daily mean duration of personal computer use, driving, precise work, commuting, time spent at home before going to bed, sleeping, attending business meetings, and performing physical labor. Statistical analysis was performed using t-tests, Chi-square tests, and logistic regression analyses. A result with P < 0.05 was considered statistically significant.ResultsThe median total score on the 4 items used to assess TRS was 5 (25% = 4, 75% = 7). Two groups were defined such that the participants scoring ≤7 were assigned to the low-TRS group and those scoring ≥8, to the high-TRS group. The high-TRS group constituted 22.6% of the subjects. Logistic regression analyses indicated that female gender and extended periods of computer use were significant contributors to the manifestation of TRS.ConclusionThis questionnaire-based study showed that gender and computer use time was associated with the prevalence of TRS in this working population. Thus, evaluation of ergonomics is suggested for TMD patients.