Computational fluid dynamics study of the pharyngeal airway space before and after mandibular setback surgery in patients with mandibular prognathism.

The purpose of this study was to investigate the relationship between the pressure drop in the pharyngeal airway space (ΔPPAS) and the minimum cross-sectional area (minCSA) of the pharyngeal airway before and after mandibular setback surgery using computational fluid dynamics, in order to prevent iatrogenic obstructive sleep apnoea. Eleven patients with mandibular prognathism underwent bilateral sagittal split osteotomy for mandibular setback. Three-dimensional models of the upper airway were reconstructed from preoperative and postoperative computed tomography images, and simulations were performed using computational fluid dynamics. ΔPPAS and the minCSA of the pharyngeal airway were calculated, and the relationship between them was evaluated by non-linear regression analysis. In all cases, the minCSA was found at the level of the velopharynx. After surgery, ΔPPAS increased significantly and the minCSA decreased significantly. The non-linear regression equation expressing the relationship between these variables was ΔPPAS=3.73×minCSA-2.06. When the minCSA was <1cm2, ΔPPAS increased greatly. The results of this study suggest that surgeons should consider bimaxillary orthognathic surgery rather than mandibular setback surgery to prevent the development of iatrogenic obstructive sleep apnoea when correcting a skeletal class III malocclusion.

Facial nerve paralysis after super-selective intra-arterial chemotherapy for oral cancer.

Facial nerve paralysis (FNP) after super-selective intra-arterial chemotherapy (SSIAC) is a relatively rare local side effect of SSIAC to the maxillary artery (MA) or the middle meningeal artery (MMA). The incidence and prognosis of FNP after SSIAC in 381 patients with oral cancer (133 with catheterization of the MA, 248 without) was investigated retrospectively. Only three patients (two male and one female) had FNP, for an incidence of 0.8%. All patients with FNP had undergone catheterization of the MA, and the incidence of FNP in this group was 2.3% (3/133). One of the three patients with FNP had paralysis of the third branch of the trigeminal nerve. FNP occurred a mean of 8.7 days (range 5-11 days) after initial SSIAC, and the mean total dose of cisplatin was 55.8mg (range 42.5-67.2mg) and of docetaxel was 25.4mg (range 17.0-33.6mg). FNP resolved completely a mean of 12.7 months (range 6-19 months) after onset. Because the administration of anticancer agents via the MA or MMA carries a risk of FNP, this information will be useful when obtaining informed consent from patients before treatment.

Radiation therapy with concurrent retrograde superselective intra-arterial chemotherapy for gingival carcinoma.

PURPOSE: The aim of this study was to review the efficacy and toxicity of radiation therapy with concurrent retrograde superselective intra-arterial chemotherapy in the treatment of gingival carcinoma. METHODS AND MATERIALS: In all, 34 patients (21 men and 13 women) with squamous cell carcinoma of the gingiva underwent radiation therapy with concurrent retrograde superselective intra-arterial chemotherapy. Treatment consisted of daily external irradiation and concurrent retrograde superselective intra-arterial infusion with cisplatin and docetaxel. A median total dose of 60 Gy in 30 fractions was delivered to tumors. RESULTS: Of the 34 patients, 29 (85 %) achieved a complete response (CR) and 5 had residual tumors. Of the 29 patients with a CR, 2 had local recurrences and 1 had distant metastasis 1-15 months after treatment. Twenty-six of the 36 patients had survived at a median follow-up time of 36 months (range 12-79 months); 4 died of cancer and 4 died of non-cancer-related causes. At both 3 and 5 years after treatment, the overall survival rates were 79 % and the cause-specific survival rates were 85 %. Osteoradionecrosis of the mandibular bone only developed in 1 patient after treatment. CONCLUSION: Radiation therapy with concurrent retrograde superselective intra-arterial chemotherapy was effective and safe in the treatment of gingival carcinoma. This treatment may be a promising curative and organ-preserving treatment option for gingival carcinoma.

Cervicofacial subcutaneous emphysema associated with dental laser treatment.

Cervicofacial subcutaneous emphysema is a rare complication of dental procedures. Although most cases of emphysema occur incidentally with the use of a high-speed air turbine handpiece, there have been some reports over the past decade of cases caused by dental laser treatment. Emphysema as a complication caused by the air cooling spray of a dental laser is not well known, even though dental lasers utilize compressed air just as air turbines and syringes do. In this study, we comprehensively reviewed cases of emphysema attributed to dental laser treatment that appeared in the literature between January 2001 and September 2012, and we included three such cases referred to us. Among 13 cases identified in total, nine had cervicofacial subcutaneous and mediastinal emphysema. Compared with past reviews, the incidence of mediastinal emphysema caused by dental laser treatment was higher than emphysema caused by dental procedure without dental laser use. Eight patients underwent CO2 laser treatment and two underwent Er:YAG laser treatment. Nine patients had emphysema following laser irradiation for soft tissue incision. Dentists and oral surgeons should be cognizant of the potential risk for iatrogenic emphysema caused by the air cooling spray during dental laser treatment and ensure proper usage of lasers.

High-dose zoledronic acid narrows the periodontal space in rats.

The aim of this experiment was to evaluate the histological effects of zoledronic acid on the periodontal space in rats. 40 male Wistar rats were divided into three zoledronic acid groups and a control group. Zoledronic acid was injected subcutaneously at doses of 10, 50, or 500 µg/kg once a week for 3 weeks. The rats were killed 1 or 9 weeks after the last injection. Histological examination of the periodontal space around the incisor tooth revealed that zoledronic acid did not inhibit tooth development. In the rats killed 1 week after treatment discontinuation, the periodontal space gradually narrowed in response to increasing zoledronic acid doses, and the changes were statistically significant according to ANOVA but not according to ANOVA with post hoc tests. The changes persisted in the high-dose zoledronic acid group despite zoledronic acid discontinuation, with significant differences identified by ANOVA and ANOVA with post hoc tests. Therefore, although zoledronic acid had an insignificant effect on tooth development, it had a significant effect on the periodontal space when high doses were administered. The results of this experiment may provide useful information for future investigations on the role of zoledronic acid in the osteonecrosis of the jaw.

An accurate maxillary superior repositioning technique without intraoperative measurement in bimaxillary orthognathic surgery.

This article describes a simple and accurate technique for maxillary superior repositioning without any intraoperative measurement using reference points that can be the source of error in bimaxillary orthognathic surgery. A bilateral straight locking miniplates (SLMs)/screw system secured to the maxilla and mandible maintains the three-dimensional relationship between the mandible and the skull base precisely like the incisor pin of an articulator in model surgery. The maxilla can then be accurately moved into the planned position identical to that in model surgery by the SLMs technique.

Mandibular reconstruction using 2-step bone transport in an irradiated cancer patient with type 2 diabetes mellitus.

This report describes mandibular reconstruction using a 2-step bone transport technique in a cancer patient with type 2 diabetes mellitus (DM) who received radiotherapy before ablative surgery. The bone, measuring 90 mm in length with the mandibular curvature and good alveolar form, was regenerated using a plate-guided method. Three implants were placed 21 months after completion of the first distraction and 14 months after the second distraction. These implants integrated successfully and have remained stable more than 2 years after loading. The results suggest that mandibular reconstruction using bone transport is possible after segmental osteotomy in irradiated cancer patients with DM, although a long treatment period is required.

Vertical distraction of a free vascularized osteocutaneous scapular flap in the reconstructed mandible for implant therapy.

This paper describes a case of vertical distraction osteogenesis of a free vascularized osteocutaneous scapular flap in the reconstructed mandible before implant therapy. The patient was a 67-year-old woman with squamous cell carcinoma of the right lower gingiva. She underwent segmental mandibulectomy for tumor ablation and reconstruction with an osteocutaneous scapular flap. The distraction protocol, clinical course and implant therapy are presented. Through this procedure, the bone height of the scapular graft increased by 10mm. Implants with adequate length could be placed in the distracted area. Two years after masticatory loading, the condition of these implants was stable. Vertical distraction osteogenesis of the scapular flap was considered effective when performed before implant therapy, to facilitate postoperative functional and esthetic restoration after tumor resection.

Curative treatment of central hemangioma in the mandible by direct puncture and embolisation with n-butyl-cyanoacrylate (NBCA).

Management of central hemangioma in the mandible is difficult because of the abundant vascular network in this region. One of the most common signs of these patients, especially in the mixed dentition period, is hypermobility of the teeth with spontaneous hemorrhage from the surrounding gingival sulcus. Various therapeutic modalities have been considered, but surgery is the most frequently used. In cases of a large extensive lesion, however, intralesional injections of sclerosing agents have often been successful. A case of central hemangioma of the mandible with arteriovenous malformations in a 10-year-old girl is reported. She was treated with direct injection of an embolic material, n-butyl-cyanoacrylate, which brought satisfactory results. Preoperative embolisation of feeder vessels with Gelfoam and Avitene soaked in thrombin together with this direct injection is a safe treatment modality that is as effective as surgery.

Tissue engineering research in oral implant surgery.

In this article, we introduce some of the more extensively evaluated technologies using concepts of tissue engineering. We report on hard tissue engineering and soft tissue engineering and their utility for dental implant therapy. For hard tissue engineering, we evaluated human recombinant bone morphogenetic protein-2 and marrow mesenchymal stem cells using a model of sinus augmentation procedure in rabbit. We also describe distraction osteogenesis as another category for hard tissue engineering. In addition, we evaluate soft tissue management using cultured epithelial grafting for soft tissue engineering. The results of our tissue regeneration materials and methods in this study are positive. When the tissue engineering materials are used in clinics in the future, implant surgery could be the leading field.

Suicide gene therapy for human oral squamous cell carcinoma cell lines with adeno-associated virus vector.

The purpose of this study was to test the possibility of gene transfer as a new therapy for oral cancer. Adeno-associated virus (AAV) has already been used in the fields of cystic fibrosis and Parkinson's disease as a potential vector for gene therapy because of its wide host range, high transduction efficiency, and lack of cytopathogenicity. Four human oral squamous cell carcinoma cell lines were transduced with an AAV vector containing the beta-galactosidase gene (AAVlacZ) in vitro. Gene transduction efficiency was from 20 to 50% at a multiplicity of infection (MOI; for the purposes of this study the number of vector genomes per target cell) of 1x10(3), and nearly 100% of each cell line were transduced at an MOI of 1x10(4). Next, four cell lines were transduced with an AAV vector containing the herpes simplex virus thymidine kinase (HSVtk) gene, which sensitizes transduced cells to ganciclovir (GCV). Subsequent administration of GCV resulted in nearly 100% tumor cell killing at an MOI of 1x10(4) and from 70 to 80% tumor cell killing at an MOI of 1x10(3). These results suggest that AAV-mediated gene transfer of HSVtk and administration of GCV has potential as a new therapy for oral squamous cell carcinoma.

Activation of BMK1 via tyrosine 1062 in RET by GDNF and MEN2A mutation.

Big mitogen-activated protein kinase 1 (BMK1) is a new member of mitogen-activated protein kinase (MAPK) family. In the present study, we investigated whether glial cell line-derived neurotrophic factor (GDNF) can induce activation of BMK1 through RET tyrosine kinase. Its activation reached a maximal level at 30 min and continued at least for 120 min after GDNF stimulation. In addition, we detected BMK1 activation in NIH3T3 cells expressing RET with a multiple endocrine neoplasia (MEN) 2A mutation. The level of BMK1 activation markedly decreased by replacement of tyrosine 1062 with phenylalanine (designated Y1062F) in RET, indicating the importance of downstream signaling via tyrosine 1062. However, although both RAS/MAPK and phosphatidylinositol 3-kinase (PI3-K)/AKT signaling pathways are activated via tyrosine 1062, BMK1 activation by GDNF was not significantly impaired by treatment with an MEK1 inhibitor, PD98059, or two distinct PI3-K inhibitors, LY294002 and wortmannin, suggesting that the RAS and PI3-K signaling pathways are not crucial for BMK1 activation by GDNF. Moreover, luciferase reporter assays revealed that RET-MEN2A mutant proteins can activate the MEF2C transcription factor that is known to be a cellular target for BMK1, and that its activation is impaired by the Y1062F mutation or by expression of a dominant negative form of MEK5.

A case of Burkitt's lymphoma that presented initially with resorption of alveolar bone.

A 16-year-old male was evaluated for a 1-month history of alveolar bone resorption, which had been treated with endodontics by a neighborhood dentist. Intraoral examination showed slight gingival swelling and teeth mobility. However, no tumor mass was seen. The panoramic image showed resorption of alveolar bone and loss of teeth lamina dura. Because he complained of general fatigue, he was introduced to the internist. Biopsies of gingiva and bone marrow aspiration revealed a massive proliferation of lymphoblasts expressing CD10, 19, 20 and HLA-DR antigens on the surface. Their karyotypes were abnormal; 46, XY, t (8;14) (q24;q32). Accordingly, he was diagnosed as Burkitt's lymphoma, and received intensive chemotherapy which relieved his symptoms and decreased his tumor. However, his disease soon became refractory to chemotherapy, and he died 11 weeks after the onset.

Trends in site-specific mortality from oral and pharyngeal cancer among Japanese males, 1950-94.

In order to obtain some etiological clues for oral and pharyngeal cancer in Japanese males, we examined mortality trends from cancer of the lip, buccal cavity and pharynx by site with other descriptive epidemiological features (1950-94). The data were obtained from Vital Statistics (Ministry of Health and Welfare, Japan). The 45-year trend in mortality was evaluated by computing crude and age-adjusted mortality rates, age-specific mortality rates, with birth cohort analysis. The crude mortality rate from cancer of the lip, buccal cavity and pharynx has increased by 3.7-fold, and age adjusted mortality rate by 1.7-fold in the 45-year period, with different mortality trends by site. In general, age-specific mortality has also been increasing with advancing age. The birth cohort analysis showed that the higher the mortality rate, the younger the birth cohort, but with different effects of birth cohort by site. Mortality from cancer of the lip, buccal cavity and pharynx has consistently been increasing in Japanese males from 1950 to 1994, with similar upward mortality trends for some specific sites.

Sarcomatous overgrowth in recurrent ameloblastic fibrosarcoma.

A case of recurrent ameloblastic fibrosarcoma (AFS) in the mandibular molar region of a 22-year-old male is reported. The tumor was first diagnosed as a sarcoma of undetermined origin, because the benign epithelial component of AFS had disappeared after repeated surgical procedures. The lesion grew rapidly in the time from hospital admission until operation, suggesting progression from low to high malignancy. The correlation between the benign epithelial component and malignancy is discussed.

New superselective intra-arterial infusion via superficial temporal artery for cancer of the tongue and tumour tissue platinum concentration after carboplatin (CBDCA) infusion.

We developed a new technique of superselective intra-arterial chemotherapy for tongue cancer using a modified (1.35 mm) angiographic catheter. The catheter was confirmed to be inserted into the lingual artery by the new technique. We measured the platinum concentrations in resected tumour tissues after infusion of carboplatin (CBDCA) at 20 mg/m2 over 30 min from 30 min before tumour resection in 12 patients with cancer of the tongue (6 patients: superselective intra-arterial infusion; 6 patients: conventional intra-arterial infusion). The mean platinum concentration in tumour tissue was 10.5 +/- 1.2 micrograms/g wet, which was more than twice higher than, and significantly different from, 4.3 +/- 3.8 micrograms/g wet by the conventional intra-arterial infusion method. This new superselective intra-arterial infusion method allows direct infusion of the anticancer agent into the artery supplying the tumour and is expected to become a new therapeutic modality for cancer of the tongue.