MANDIBULOTOMY, A SURGICAL APPROACH FOR ORAL CANCER : ITS COMPLICATIONS AND CONTRIBUTING FACTORS

We reviewed 56 patients who received mandibulotomy at Yonsei medical center between 1989 and 1999. We also analysed the complications associated with mandibulotomy and its contributing factors. The complications occur in 16 patients(28.6%) and are classified into two categories; intraoperative and postperative complications. Nonunion was observed in 5 patients and osteoradionecrosis in 5. The patients who received preoperative radiation therapy were more tend to develop nonunion and osteoradionecrosis. This study suggests the benefits of mandibulotomy as a surgical approach to oral cancer: 1. Paramedian osteotomy was recommended for preservation of neurovascular bundle and ease of surgical access. 2. By using thin saw blade, reapproximation was improved with minimal bone loss. 3. osteotomy on anterior mandible which lies outside the usual portals of radiation therapy decreases the incidence of osteoradionecrosis.ope

Management of Osteoradionecrosis of the Mandible in Patients with Oral and Oropharyngeal Cancers

BACKGROUND AND OBJECTIVES: Osteoradionecrosis (ORN) of the mandible is one of the most serious complications following radiotherapy for oral and oropharyngeal cancer. However, the predisposing factors and clinical course of ORN are variable and its proper management is currently undetermined. The objective of this study is to review our ORN cases and evaluate the treatment methods. PATIENTS AND METHODS: We retrospectively reviewed 57 cases of oral and oropharyngeal cancers, where patients received combined surgery and radiotherapy from 1990 to 1998. Osteoradionecrosis occurred in 5 cases, and we evaluated the predisposing factors, clinical course and results of treatments. Four patients were treated with radical sequestrectomy and open reduction of mandible. Of these four patients, three received the combined treatment with hyperbaric oxygen (HBO) therapy, and one received the conservative treatment. RESULTS: Four ORN cases occurred at the lateral mandibulotomy site and one case arose at the opposite mandibular body unrelated to osteotomy. The interval between ORN and radiotherapy was so variable as 3 to 140 months. Four patients were successfully treated with the combined surgical and HBO therapies (3 cases) or with the conservative treatment (1 case). The remaining case could not be controlled by surgical treatment without HBO. CONCLUSION: Osteoradionecrosis usually occurred at lateral mandibulotomy sites, especially combined with sagittal partial mandibulectomies. We recommend that lateral mandibulotomies should, whenever possible, be avoided if the radiotherapy is planned postoperatively. And the patients who received radiotherapy at the mandible should be observed for osteoradionecrosis for long time. Our treatment results suggest that a combined surgery with HBO therapy can be a primary treatment modality for ORN.ope

Handheld Near-Infrared Fluorescence Imaging Device Using Modified Action Cameras for Peri-Operative Guidance of Microvascular Flap Surgery

Indocyanine green near-infrared fluorescence (ICG-NIRF) imaging has recently come into use as a novel method in peri-operative microvascular flap assessment. However, a majority of the many commercial devices launched for clinical use lack mobility, portability, and cost-efficiency and are thus unsuitable for intra-oral applications. This study introduces a cost-effective, customized, handheld NIRF device following principles of ICG-NIRF imaging. Moreover, the novel characteristics of our prototype, considered in conjunction with a literature review highlighting the significance of fluorescence devices in microvascular surgery, point to a new generation of devices for use in microvascular flap surgery.ope

ccuracy of preoperative assessments for cervical lymph node metastasis in oral cancer

Purpose : The aim of this study was to determine the accuracy of clinical and radiologic assessments in detecting positive cervical lymph nodes in oral cancer. Materials and Methods : We had reviewed the preoperative clinical, radiologic and postoperative histopathologic reports of 46 patients who had been diagnosed as oral cancer and underwent surgical excision combined with neck dissection (52 sides of neck) in the Department of Oral and Maxillofacial Surgery, College of Dentistry, Yonsei University from the July 1, 1992 to the April 30, 1999. Results : The results were as follows 1. The male to female ratio was 4.38 : 1 and the mean age was 57. 2. Sensitivity values for the preoperative assessment of cervical lymph node metastasis in oral cancer were 62.5 % in clinical examination and 50.0 % in radiologic assessments. Specificity values were 77.8 % in clinical examination and 94.4 % in radiologic assessments. 3. False positive values were 44.4 % in clinical examination and 20.0 % in radiologic assessments. False negative values were 17.6 % in clinical and 19.0% in radiologic assessments. 4. Overall efficiency values were 73.1 % in clinical examination and 80.8 % in radiologic assessments. Summary : There were some limits on the accuracy of clinical and radiologic assessments in the preoperative detection of the cervical lymph nodes in oral cancer. To improve the accuracy, it is important to communicate between clinician and radiologist, and adjunctive diagnostic measures, ultrasound and fine needle aspiration cytology, were helpful increasing the overall efficiency. In the high risk sites (oral tongue and floor of the mouth) the false negative value is higher and the overall efficiency in radiologic evaluation is lower than those of the low risk sites (gingiva and alveolar ridge, retromolar trigone and buccal mucosa). The elective neck dissection should be considered in the high risk sites.ope

Rapid canine retraction in a Class II bialveolar protrusion case using a lingually extended distraction screw

Rapid canine retraction, first introduced by Liou, is a distraction osteogenesis applied to the periodontal ligament tissue. Rapid tooth movement was facilitated by establishing minimal bony resistance on the distal surface of the canine by socket preparation and by osteogenesis on the mesial side in response to the periodontal distraction. Since undesired buccal tipping or extrusion of the canine during retraction tends to occur, it is crucial to maintain the firm path of movement and the axis of the canine during retraction. In order to improve the predictability of the canine movement, lingually extended distraction screws with heavy labial guiding wires were designed. Prefabricated plastic canine models for the estimation of socket depth and miniscrew implants for anchorage reinforcement were also devised. Applying these devices to a female patient with Class II anterior protrusion, the whole treatment was effectively finished in 13 months. Loss of vitality or periodontal problems did not occur throughout treatment, and stable occlusion was maintained during 10 months of retention. This case report demonstrates that a predictable rapid canine retraction can be achieved through the use of this modified technique.ope

SAGITTAL MANDIBULECTOMY IN TONSILLAR CANCER

Sagittal mandibulectomy provided safe oncologic margins and functional and esthetic advantages in the surgical treatment of tonsillar cancers that abut but do not infiltrate the mandible.ope

Clinicopathologic study of pleomorphic adenoma in minor salivary glands

Pleomorphic adenoma is the most common salivary neoplasm mainly occurring in the major salivary glands - especially in parotid gland, which is characterized by variable histopathologic appearances and high recurrence rate with malignant transformation according to surgical situations. And this benign mixed tumor occurring in minor salivary glands is believed to shows same clinicopathologic appearances and relatively low recurrent rate compared with the case in major salivary glands. But there are few comparative studies of large series of pleomorphic adenoma occurring in minor salivary glands which includes different histopathologic appearance, clinical characteristics, treatment methods, recurrence rate, and malignant transformation. We retrospectively studied the 54 patients who were pathologically confirmed with pleomorphic adenoma occurring in minor salivary glands, and analyzed the clinico-histopathological appearance, surgical methods, recurrent cases. The results obtained are as follows. 1. The incidence of the tumor was most frequent in 4th & 5th decade, and in female. 2. Palate(90%) including hard & soft palate was the most frequent site for pleomorphic adenoma in minor salivary glands. 3. The exact duration could not be known due to asymptomatic slow growth patterns of the tumor. 4. The mean tumor size was 2.3cm. 5. 28 (52%) pleomorphic adenomas were classified as Cellular type (cell-rich), 17 (31%) specimen as Intermediate type(equal cell to stroma ratio), and 9 (17%) as Myxoid type(stroma-rich). 6. Surgically 51 cases (94%) were showed well-encapsulated tumors, but histopathologically only 34 specimen (63%) were wellencapsulated. Therefore pleomorphic adenomas in minor salivary glands also have to be excised more widely, not enucleated. And in case of suspicious malignancy or large tumor, preoperative incisional biopsy can be applied in the center of the tumor for prevention of rupture of tumor cell, and total excision with use of frozen biopsy for detection of malignancy and confirming the excision margin, and closed follow-up according to final histopathologic results is recommended.ope

Tissue-engineered reconstitution of oral mucosa using polydioxanone mesh

The lack of sufficient oral mucosa available for intra-oral reconstruction has been dealt with by the use of skin or oral mucosa grafts harvested from donor sites but grafts requires more than one surgical procedures and could cause donor site morbidity. Many investigators have attempted to increase available soft tissue by tissue engineered skin or oral mucosa replacements for clinical applications. But, reconstructed mucosa by several methods have low physical properties such as rolling and contraction. The aims of this study were to develope an in vitro experimental model that maintains an epithelial-mesenchymal interaction by organotypic raft culture, and to characterize biologic properties of three-dimensionally cultured oral mucosa embedded with Polydioxanone mesh by histological and immunohistochemical analysis. The results were as follows; 1. Oral mucosa reconstructed by three-dimensional organotypic culture revealed similar morphologic characteristics to equvalent normal oral mucosa in the point that they show stratification and differentiation. 2. The expression of cytokeratin 10/13 and involucrin in the cultured tissue showed the same pattern with normal oral mucosa suggesting that organotypic co-culture condition is able to induce cellular differentiation. 3. After insertion of polydioxanone mesh, increased tensile strength were observed. These results suggest that three-dimensional organotypic co-culture of the oral mucosa cell lines with the dermal equvalent consisting type I collagen and fibroblasts reproduce the morphologic and immunohistochemical characteristics similar to those in vivo condition. And increased physical properties by use of polydioxanone mesh will helpful for clinical applications.ope

Chios mastic gum extracts as a potent antitumor agent that inhibits growth and induces apoptosis of oral cancer cells.

PURPOSE: The purpose was to investigate Chios mastic gum (CMG) extract as an potential anti-tumor agent for oral squamous cell carcinoma in vitro. METHODS: We designed a study to examine the effects of CMG extracts on growth of oral squamous cell carcinoma cell line, YD-10B and to determine whether the extracts could induce apoptosis through the activation of caspase-3, using the common chemotherapeutic agent Paclitaxel (Taxol, Bristol-Myers Squibb) as a control. RESULTS: MTT assay suggested that both CMG and Taxol inhibited the proliferation of YD-10B cells in a time and dose dependent manner. Moreover, 10 μg/mL of CMG and 50 μg/mL of Taxol caused fragmentation of the genomic DNA at 24 hour. Finally, 10 μg/mL of CMG and 50 μg/mL of Taxol caused cleavage of procaspase-3 in western blot analysis. CONCLUSIONS: These results suggest CMG's potential as an anti-tumor agent.ope

Possibility of the use of public microarray database for identifying significant genes associated with oral squamous cell carcinoma.

There are lots of studies attempting to identify the expression changes in oral squamous cell carcinoma. Most studies include insufficient samples to apply statistical methods for detecting significant gene sets. This study combined two small microarray datasets from a public database and identified significant genes associated with the progress of oral squamous cell carcinoma. There were different expression scales between the two datasets, even though these datasets were generated under the same platforms - Affymetrix U133A gene chips. We discretized gene expressions of the two datasets by adjusting the differences between the datasets for detecting the more reliable information. From the combination of the two datasets, we detected 51 significant genes that were upregulated in oral squamous cell carcinoma. Most of them were published in previous studies as cancer-related genes. From these selected genes, significant genetic pathways associated with expression changes were identified. By combining several datasets from the public database, sufficient samples can be obtained for detecting reliable information. Most of the selected genes were known as cancer-related genes, including oral squamous cell carcinoma. Several unknown genes can be biologically evaluated in further studies.ope