Shinjiro Aoki

Gene mutation analysis and immunohistochemical study of β-catenin in odontogenic tumors

In the present study the significance of nuclear/cytoplasmic expression of β‐catenin (CTNNB1) and mutation of the CTNNB1 gene (CTNNB1) in odontogenic tumors was examined. Six ameloblastomas (five follicular ameloblastomas and one plexiform ameloblastoma) and three malignant odontogenic tumors (one metastasizing ameloblastoma, one ameloblastic carcinoma, and one primary intraosseous odontogenic carcinoma) were investigated for CTNNB1 expression and CTNNB1 mutation. Immunohistochemically, all follicular ameloblastomas and one primary intraosseous odontogenic carcinoma exhibited focal and moderate nuclear/cytoplasmic expression of CTNNB1, whereas the plexiform ameloblastoma and the remaining two malignant odontogenic tumors had entirely membranous expression. CTNNB1 mutation at codon 40 of exon 3 was found in one of the six follicular ameloblastomas. The other five follicular ameloblastomas, the plexiform ameloblastoma, and the three malignant odontogenic tumors did not show mutation in exon 3 of CTNNB1. These findings further confirmed that CTNNB1 mutation is not frequent in ameloblastoma and malignant odontogenic tumors, although the abnormality of Wnt signaling may be associated with some of these tumors.

Comparison between hockey stick and reversed hockey stick incision: gently curved single linear neck incisions for oral cancer

Hockey stick incision (HSI) and reversed-HSI are known to be useful incisions for lymph node dissections of the neck. Both are gently curved single linear incisions without three-point suture line junctions, but are different at the base of the skin flap. The HSI allows the elevation of a superiorly-based single cervical skin flap and the reversed-HSI allows for an inferiorly-based flap. We compared the viability of the skin flaps, exposure of the operation field and cosmetic results to evaluate the characteristics of each incision. HSI appeared to be the suitable incision for radical neck dissection due to adequate exposure of the operation field while rendering excellent cosmetic results. Reversed-HSI was applied in combination with block resection of parts of the oral cavity because it provided much better exposure of the operation field than HSI, while still achieving acceptable cosmetic results. Using this technique, a small area of marginal necrosis was occasionally seen at the apex of the skin flap due to poor blood supply.

Osteosynthesis and simultaneous irregular trifocal distraction osteogenesis for segmental mandibular defect after tumor ablative surgery: a case report

OBJECTIVE This paper describes a case of secondary mandibular bone reconstruction performed to place dental implants. Osteosynthesis and simultaneous irregular trifocal distraction osteogenesis were documented. PATIENT The patient was a 51-year-old man with recurrent ameloblastoma of the mandible. Segmental mandibulectomy for tumor ablation and immediate mandibular reconstruction were performed. Because the volume of reconstructed bone was insufficient to place dental implants, trifocal distraction osteogenesis (vertical and horizontal distraction osteogenesis) was performed. Because the mandible had lost its continuity, osteosynthesis was performed simultaneously. RESULTS Through this procedure, the bone was well augmented. Absorption of the distracted bone was not seen. Adequate-length implants were placed. CONCLUSION Irregular trifocal distraction osteogenesis synchronized with osteosynthesis shortened the treatment period and produced stable bone augmentation for placement of dental implants. Therefore, this procedure could be indicated for complicated segmental mandibular bone defects.

Ultrasonic vertical osteotomy of the distal segment for safe elimination of interference between the proximal and distal segments in bilateral sagittal split osteotomy for mandibular asymmetry.

ilateral sagittal split osteotomy (BSSO) is commonly used n the correction of dentofacial deformities. However, in cases f facial asymmetry with a shift of the mandibular midline r occlusal cant, the condyle is displaced laterally by the ulling of the proximal segment medially when there is bony nterference between the proximal and distal segments after he osteotomy. When the gap between the proximal and disal segments is large, the proximal segment will clearly be symmetrical as a lateral bulge on the patient’s cheek, even f a large piece is removed. To overcome these problems, llis reported a vertical osteotomy of the distal segment ehind the terminal molar to passively align the segments f the sagittal ramus osteotomy.1 This procedure can also e used to improve the angle of the occlusal plane and cclusal stability when rotating the maxillomandibular comlex counterclockwise.2 When the inferior alveolar nerve IAN) is exposed, it is retracted laterally and the vertical steotomy made. However, the IAN is not always exposed ecause surgeons seek to minimise its exposure to prevent njury. As there is the potential for such injury during verical osteotomy of the distal segment when a conventional ur or saw is used, we have developed an ultrasonic vertial osteotomy of the distal segment to eliminate interference

Modified Sagittal Splitting Ramus Osteotomy by Epker's Method. Comparison with Obwegeser-Dal Pont's Method.

Since 1989, modified sagittal splitting ramus osteotomy, as modified by Epker in 1977: for surgical correction of mandibular skeletal deformities, has been used at our hospital. Advantages of this procedure are safety, capability of rotating the distal segment horizontally, and maintaining a blood supply to the proximal segment. Compared with Obwegeser-Dal Ponts method, there were no obvious differences in operating time and hemorrhage dose, but the frequency of mental nerve paresthesia was decreased by Epkers method. Minimized soft tissue dissection and short lingual cut of the medial ramus can reduce many complications and simplify the operative procedure. It was suggested that modified sagittal splitting osteotomy by Epkers method was very useful for surgical-orthodontic correction of mandibular prognathism.