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Dive into the research topics where Masahiro Michizawa is active.

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Featured researches published by Masahiro Michizawa.


Journal of Trauma-injury Infection and Critical Care | 2011

C-arm-guided reduction of zygomatic fractures revisited.

Tomoaki Imai; Masahiro Michizawa; Gentaro Fujita; Hidetaka Shimizu; Yoshiyuki Ota; Tetsuhisa Kitamura; Hiroshi Ichiyanagi; Tatsuro Kai

BACKGROUND Anatomic reduction of the zygomatic arch, a key surgical landmark for midfacial width and projection, is essential for the treatment of combined fractures of the zygomaticomaxillary complex and zygomatic arch. Reduction control in surgery for this common facial fracture would be facilitated by intraoperative real-time assessment using widely available and reliable equipment. Although C-arm fluoroscopy is routinely used in the repair of orthopedic fractures, its use in the maxillofacial region, particularly for combined zygomatic fractures, has been scarcely reported. METHODS We prospectively evaluated C-arm-guided reduction in 38 patients of combined zygomatic fracture without concurrent craniofacial fractures. Patients were classified according to the presence or absence of bone contact in the displaced zygomatic arch, namely as conserved (C) and loss (L) types, respectively. Reduction status was determined by the degree of recovery of the malar prominence and arch shape. RESULTS In all cases, C-arm imaging clearly displayed the displaced zygomatic arch and body in a single image. Cumulative fluoroscopic time was a few minutes in all cases. Total reduction status was excellent in 21 patients and good in 17. No case was classified as fair or poor. Repair was significantly more favorable in type C than in type L cases (p = 0.0016). CONCLUSIONS In combined zygomatic fractures, the C-arm technique provides easy, flexible, and time-efficient adjustment. Its comprehensive imaging for zygomatic arch shape and body contour markedly facilitates the control of fracture reduction and protects against unexpected, unsatisfactory outcomes.


Journal of Oral and Maxillofacial Surgery | 2013

Necrotizing sialometaplasia in a patient with an eating disorder: palatal ulcer accompanied by dental erosion due to binge-purging.

Tomoaki Imai; Masahiro Michizawa

This report describes a case of necrotizing sialometaplasia (NS) accompanied by significant dental erosion of the maxillary teeth of the palatal surfaces owing to chronic self-induced vomiting. This observation contributed to the determination of an immediate and appropriate provisional diagnosis of NS in a patient with an eating disorder, which subsequently was confirmed histopathologically as NS. The diagnostic challenges presented by NS associated with eating disorders and its management are discussed.


Journal of Oral and Maxillofacial Surgery | 2011

Anterior dislocation of the intact mandibular condyle caused by fracture of the articular eminence: an unusual fracture of the temporomandibular joint apparatus.

Tomoaki Imai; Masahiro Michizawa; Makoto Kobayashi

i t d t Maxillofacial injuries often involve fractures of the temporomandibular joint (TMJ) apparatus, which occur predominantly in the condylar process of the mandible. Fractures of the temporal bone portion of the TMJ, such as the glenoid fossa or articular eminence, are another important group of injuries dealt with by maxillofacial specialists. Fractures of the glenoid fossa are occasionally revealed by imaging for serious head injuries or mandibular trauma. A notable manifestation of glenoid fossa fractures is dislocation of the mandibular condyle into the middle cranial fossa, of which approximately 50 cases have een reported. Reports on articular eminence fractures are scarce, however, possibly because of their rare occurrence or often-obscured presentation in the presence of other more serious injuries. Reported cases have been treated conservatively or by surgical intervention only after an incidental finding during operative wound repair. This report presents an unusual type f articular eminence fracture exhibiting a disturance of mouth closing and anterior dislocation of the


Oral Surgery, Oral Medicine, Oral Pathology, and Oral Radiology | 2013

Closed reduction of mandibular condyle fractures using C-arm fluoroscopy: a technical note

Tomoaki Imai; Masahiro Michizawa; Naofumi Yamamoto; Tatsuro Kai

We describe a C-arm technique for mandibular condylar fractures in an anatomic study using a model skull and show its feasibility in a clinical case. The C-arm allowed posterior-anterior visualization of the condylar process. The X-ray axis was canted ∼15 degrees cranially to the Frankfort horizontal line. The skulls sagittal plane was rotated ∼15 degrees ipsilaterally to the X-ray axis. This technique facilitates clear visualization of the condylar neck with easy, flexible, and timely adjustments. In selected cases, this method would convert the clinical settings of the condylar fracture pattern to that which would not be amenable to an open approach, making possible minimally invasive surgical procedures.


Journal of Craniofacial Surgery | 2013

Nodular fasciitis in the buccal region with rapid growth after incisional biopsy mimicking sarcoma.

Tomoaki Imai; Masahiro Michizawa; Mitsuhiro Nakazawa

Nodular fasciitis (NF) is a reactive and proliferative fibroblastic lesion that occurs predominantly in the upper limbs but rarely develops in the oral cavity. This lesion can be misdiagnosed as malignant owing to its frequent display of rapid growth, rich cellularity, and high mitotic activity. Unlike a sarcoma, NF can resolve spontaneously or after an incisional biopsy. We describe a challenging case involving a lesion in the buccal region that rapidly enlarged after incisional biopsy. This variation of clinical behavior illustrates the difficulty in predicting whether NF will continue to grow or regress. Clinicians dealing with cases of an enlarging fibrous lesion of short duration should remain aware of this disease entity and its potential diagnostic dilemma.


Oral Surgery, Oral Medicine, Oral Pathology, and Oral Radiology | 2014

Life-threatening oronasal hemorrhage managed by transcatheter embolization of bilateral maxillary arteries in an elderly patient with comminuted LeFort I fracture

Tomoaki Imai; Masahiro Michizawa; Naofumi Yamamoto; Jiro Oba; Hirotaka Sawano

Massive orofacial hemorrhage mostly occurs in younger individuals unilaterally and is associated with extensive LeFort fractures. Here we describe a 91-year-old man who sustained a life-threatening hemorrhage of the bilateral internal maxillary artery (IMA) system with a comminuted LeFort I fracture caused by a road traffic accident while he was driving. His injury severity score was high (34), but no severe brain injury was sustained. Transarterial embolization (TAE) was performed to control the intractable hemorrhage. The patient survived and has an acceptable outcome. Although rare, this case may be representative of a trend in maxillofacial injuries in the elderly resulting from worldwide motorization and steady aging of more active populations. Life-threatening hemorrhage of the bilateral IMA system occurs even in LeFort I fractures. Controlling an intractable oronasal hemorrhage with TAE would lead to survival with less severe morbidity, even for the very elderly with no severe brain injuries.


Journal of Craniofacial Surgery | 2014

Phoenix jaw-bone regeneration of the necrotic mandible between pathological fractures: an unusual but evocative course of bisphosphonate-related osteonecrosis.

Tomoaki Imai; Masahiro Michizawa


Japanese Journal of Oral & Maxillofacial Surgery | 1998

Clinicostatistical study of oral and maxillofacial soft tissue injuries in children classified according to developmental stage

Yasuyuki Kano; Junichiro Nukata; Chigusa Nakanishi; Yoshiyuki Ohta; Masahiro Michizawa; Riki Matsumoto; Hiroshi Tamura; Motoo Suematsu; Masayoshi Sakuda


Japanese Journal of Oral & Maxillofacial Surgery | 1993

A clinico statistical study of 123 condylar fractures of the mandible

Junichiro Nukata; Riki Matumoto; Hiromi Fujishiro; Masahiro Michizawa; Tadayuki Inatani; Yasuyuki Kano; Yoshiyuki Jotoku; Hiroshi Tamura; Hiroshi Uchida; Masayoshi Sakuda


Journal of the Japanese Stomatological Society | 2013

A case of peripheral ameloblastoma with massive bone resorption

Gentarou Fujita; Masahiro Michizawa; Tomoaki Imai; Naonori Yamamoto; Yoshiaki Yura

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