• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.1
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• pp.41-51
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• 2008

Mucoepidermoid carcinoma (MEC) is the most common malignant salivary gland tumor which compromises about 6$\sim$8% of all tumors followed by the adenoid cystic carcinoma (ACC) and adenocarcinoma. Most deaths from salivary carcinomas are caused by recurrent or metastatic lesions that are resistant to conventional therapy. Therefore, knowledge of cellular properties and tumor-host interactions that influence the vascular metastasis is important for the design of more effective therapy of salivary carcinomas. Neoangiogenesis is essential for tumor growth, which is postulated to be fundamentally dependent on the induction of stromal neovascularization. However, how neovascularization takes place in live tissue has not been fully established, especially in recruitment and differentiation of endothelial cells in the salivary gland tumors. Vascular endothelial growth factor (VEGF) is a heparin-binding, dimeric polypeptide growth factor known to exert its mitogenic activity specifically on endothelial cells. VEGF has been shown th be directly involved in angiogenesis, which in essential for the pathogenesis of many solid tumors. von Willebrand factor (vWF) is a large multimeric protein synthesized by megakaryocytes and endothelial cells that enable platelets to adhere to exposed subendothelium and, as well, to respond to changes in the blood flow. Recent studies suggest that increased levels of vWF correlate with progression of disease, metastasis, or survival time and thus may have a prognostic significance. vWF is explained as an acute phase proteins which is increased in cancer or as a result of increased endothelial cell synthesis associated with tumor-induced angiogenesis. Due to adhesive properties of vWF, its increased concentrations may also contribute metastasis of tumor. In this study, we determined the mRNA expression of VEGF and vWF in salivary ACC, MEC and pleomorphic adenoma by in situ hybridization. As a result, stronger expression of VEGF and vWF was seen in salivary ACC and MEC which has more invasive nature than the salivary benign tumor.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.1
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• pp.52-59
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• 2008

The geometric design of an implant surface may play an important role in affecting early osseointegration. It is well known that the porous surfaced implant had much benefits for the osseointegration and the early stability of implant. However, the porous surfaced implant had weakness from the transgingival contamitants, and it resulted in alveolar bone loss. The other problem identified with porous surface implant is the loss of physical properties resulting from the bead sintering process. In this study, we developed the new bead coating implant to overcome the disadvantages of porous surfaced implant. Ti-6Al-4V beads were supplied from STARMET (USA). The beads were prepared by a plasma rotating electrode process (PREP) and had a nearly spherical shape with a diameter of 75-150 ${\mu}m$. Two types of titanium implants were supplied by KJ Meditech (Korea). One is an external hexa system (External type) and the other is an internal system with threads (Internal type). The implants were pasted with beads using polyvinylalcohol solution as a binder, and then sintered at 1250 $^{\circ}C$ for 2 hours in vacuum of $10^{-5}$ torr. The resulting porous structure was 400-500 ${\mu}m$ thick and consisted of three to four bead layers bonded to each other and the implant. The pore size was in the range of 50-150 ${\mu}m$ and the porosity was 30-40 % in volume. The aim of this study was to evaluate the osseointegration of the newly developed dental implant. The experimental implants (n=16) were inserted in the unilateral femur of 4 mongrel dogs. All animals were killed at 8 weeks after implantation, and samples were harvested for hitological examination. All bead coated porous implants were successfully osseointegrated with peripheral bone. The average bone-implant contact ratios were 84.6 % (External type) and 81.5 % (Internal type). In the modified Goldner's trichrome staining, new generated mature bones were observed at the implant interface at 8 weeks after implantation. Although, further studies are required, we could conclude that the newly developed vacuum sintered Ti-6Al-4V bead coating implant was strong enough to resist the implant insertion force, and it was easily osseointegrated with peripheral bone.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.1
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• pp.60-71
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• 2008

The objective of this study is to evaluate the stress distribution according to the thread design and the marginal bone loss of a single unit dental implant under the axial and offset-axial loading by three dimensional finite element analysis. The implants used had the diameter of 5mm and 4mm with 13mm in length and prosthesis with a conical type which is 6mm in height and 12mm in diameter. The thread designs were triangular, square and buttress. In the three dimensional finite element model with $15\times15\times20mm$ hexahedron and 2mm cortical thickness, implants were placed with crown to root ratio 7:12, 10:9, 13:6 and 16:3. And additionally the axial force of 100N were applied into 0mm, 2mm and 4mm away from the center of the implants. The results were as follows 1. The maximum von-Mises stress in cortical bone was concentrated to cervical area of implant, and in cancellous bone, apical portion. 2. Comparing the von-Mises stresses in cortical bone of 2mm and 4mm offset loading with central axial loading, it were increased to 3 and 5 times in diameter 4mm implant, and 2 and 4 times, in diameter 5mm implant. 3. The square threads were more effective than the triangular and butress as the longer diameter, the offset loading, and the worse crown to root ratio. 4. The von-Mises stresses were relatively stable until crown to root ratio 13:6, but it was suddenly increased at 16:3. From the results of this study, minimum requirement of crown to root ratio of implant is 2:1, and in the respect of crown to root ratio, diameter and offset loading, square threads are more effective than triangular and buttress threads.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.5
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• pp.396-405
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• 2010

Purpose: This study was performed to find out the effects of the Er:YAG laser (Key Laser) & Er,Cr:YSGG laser (Water Laser) on inflammatory tissues. Materials and Methods: It was performed on about 20 g, 6 weeks male ICR mouses. They were grouped into the control (negative), the inflammation induced 'control'(positive), Er,Cr:YSGG laser exposured group after inducing inflammation, Er:YAG lasere exposured group after inducing inflammation each 15 mouses. The mouses were applicated 0.5% DNFB 1 cc on ear skin twice a day for 4 days until symptom expression. After laser exposure, ear tissues were extracted and defined gene expression by RT-PCR. Then, tissue staining, lymphocytes observation, electromicroscophic laboratory were carried out. Results: Interleukin-$1{\beta}$ was expressed much less in the A-laser exposed group. Interleukin-$1{\beta}$ & Tumor Necrosis Factor-${\alpha}$ were expressed 7 times lesser in the A-laser exposed group. The number of Lymphocytes related to inflammation was decreased rapidly in the A-laser exposed group in vivo. he number of cavity recovered normal was a little bigger in the A-laser exposed group after 5 days Conclusion: The expression of IL-$1{\beta}$ & TNF-${\alpha}$, hitologic change, observation with electron microscope shows that Erbium laser exposure causes lesser inflammation with A-laser rather than B-laser.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.5
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• pp.389-395
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• 2010

Purpose: Although it is generally accepted that patients with controlled diabetes have similar rates of success for dental implants as healthy individuals, the use of dental implants in diabetic patients is controversial. In addition, the impact of diabetes on the healing of bone associated with immediately place dental implants is not completely understood. The purpose of this study was to measure bone response to implants radiologically in uncontrolled and insulin-controlled diabetic rats. Materials and Methods: Twenty rats were divided into control, insulin-treated and diabetic groups. The rats received streptozotocin (60 mg/kg) to induce diabetes; animals in the insulin-treated group also received three units of subcutaneous slow-release insulin. Two titanium implants ($1.2{\times}3$ mm) were placed in the extraction socket of the maxillary first molars of the animals and were harvested at 3 days, 1, 2 and 4 weeks. The bone density was measured by digital radiography using gray-level analysis (histogram) in the regions of interest (ROI) at four points: two mesial and two distal to both sides of the implant. Results: The results showed that the osseointegration of the implants was impaired in the diabetic rats compared to the control and the insulin-treated rats. The radiographic evidence demonstrated marked destruction of bone around the implants in the diabetic group. Both the control and the insulin-treated groups had a significantly higher bone density on radiograph than the diabetic group from the 1 week of the experiment (P<0.05 for each comparison). Conclusion: The present study revealed that the immediate placement of titanium implants in the maxilla of diabetic rat lead to delay in the maturation of bone adjacent to implants. It is expected that the reduced predictability of success of immediate implantation in patient with the uncontrolled diabetes.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.6
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• pp.511-520
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• 2010

Purpose: This study was conducted in order to compare the efficacy of osseointegration of three different calcium metaphosphate (CMP) coated implants in the rabbit's femur. Materials and Methods: Twenty four rabbits and three different type of CMP coated implants and RBM implants were used in this study. The animals were divided into 4 groups on the basis of implant surface characteristics. Two implants were installed into the condyle of femur of each rabbits. The animals were sacrificed at 2 and 4 weeks after installation. The undecalcified specimens were prepared for histological, radiological examination and histomorphometric analysis of implant-bone contact ratios (BIC) and bone area ratio (BA). Results: Two implants were failed to osseointegrate and implant success rate was 95.2%. There were not any significant inflammatory response in all groups. Fluorescent image at 4 weeks shows that remodeling is slower in RBM group than CMP group. CMP III showed more active remodeling than CMP I, II. In histomorphologic analysis, BIC ratio at 2 weeks was lower than 4 weeks. Conclusion: The results suggest that the ratios of CMP coated implants were higher than that of RBM control group but there is no significantly difference between RBM group and CMP group. In conclusion, CMP coated implant had more clinical availability than RBM implants.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.6
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• pp.504-510
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• 2010

Purpose: This study was to examine the proliferation and function of the adipose tissue-derived endothelial cells according to different culture medium conditions. Materials and Methods: Adipose tissue-derived CD146 positive endothelial cells were cultured in according to different culture mediums (DMEM culture medium with or without osteogenic inductive agents and EBM-2 culture medium with or without osteogenic inductive agents). The proliferation and function of the adipose tissue-derived endothelial cells was examined in different culture medium conditions. Results: Adipose tissue-derived endothelial cells formed tube-like structures on Matrigel in EBM-2 culture medium with or without osteogenic inductive agents. However, the cells did not form tube-like structures on Matrigel in DMEM medium with or without osteogenic inductive agents. After 24 hours of culture, among the culture medium using EBM-2, the proliferation of the cells were promoted in EBM-2 medium without osteogenic inductive agents than in EBM-2 medium with osteogenic inductive agents. However, 72 hours of culture, the proliferation of the cells were promoted in EBM-2 medium with osteogenic inductive agents than in EBM-2 medium without osteogenic inductive agents. Conclusion: These results suggest that the proliferation and function of the adipose tissue-derived CD146 positive endothelial cells could be maintained in EBM-2 with osteogenic inductive agents.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.6
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• pp.497-503
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• 2010

Purpose: The purpose of this study is to induce artificial arthritis on rabbit TMJ by injecting collagenase. Materials and Methods: An experimental animal model of arthritis induced by surgical method or intraarticular injection of chemical agent like LDH, papain, ketorolac. Surgical method is complex and needs a long time in inducing arthritis. Intra-articular injection of chemical agent like LDH, papain, ketorolac is simple. But chemical agent like LDH, papain, ketololac needs multiple injections to induce arthritis and mechanism inducing arthritis was known. Collagenase destroys helical domain of type II collagen in extracellular matrix produced by chondrocyte and then induces arthritis. We injected collagenase (0.5, 1.0, 2.0 mg) into the temporomandibular joint of rabbit. In the control group saline was intra-articularly injected. The condylar cartilage, disk and synovia were histologically examined at 1, 2, 4, 6 weeks after the initiation of collagenase injections. Results: Four weeks after injection of 2.0 mg collagenase, we could see histologic change like arthritis. In other groups, we couldn't see arthritis-like change. Conclusion: In our study, we produce arthritis on temporomandibular joint of rabbit by using injection of collagenase in temporomandibular joint of rabbit. And this experimental osteoarthritis is a useful animal model.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.1
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• pp.57-61
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• 2010

Objective: Second primary malignancy (SPM) that occur in various period and region are important factors that deteriorate long-term survival rate in patients who recovered from oral cancer. Researches such as chemoprevention are being tried to reduce occurrence of SPMs. Only if analysis of clinical features of patients who develop SPM such as period, region and factors precedes, adequate prevention and treatment of SPM is possible. But, there are few researches about clinical features of SPMs that have primary lesion in oral cavity. In this study, we analysis that occurrence rates, regions that happen, risk factors and effect to survival rates of 2nd primary malignancies in oral cancer patients. From this survey, we willing to collect basic data for prevention and early diagnosis of SPMs. Methods: The medical records of 139 patients of oral oncology clinic of National Cancer Center who had up to 2-years follow up records after surgical or radiological treatment due to squamus cell carcinoma of oral cavity were reviewed. In these patients, survey of occurrence rate of SPMs, duration, survival rate and risk factors about occurrence of SPMs such as history of smoking, body mass index, age, sex, stage of primary lesion and history of radiologic treatment were achieved. Results: There are 15 patients who developed SPM in 139 cases. The actual occurrence rate of SPM was 10.79% and SPM were more likely to occur in male patients with 11 male Vs 4 female patients. Median age of these patient is 61.47 within 32 to 74 range. The regions that develop SPM are oral cavities (2 cases), stomach (4 cases), esophagus (2 cases), lung (2 cases) and others (1 case each breast, larynx, cervix, liver and kidney). In addition, metachronous cancers were 11 cases which happened more common than 4cases of synchronous cancers. Surveys of risk factors that relate to development of SPMs, such as sex, age, history of radiologic treatment, body mass index, history of smoking and stage of primary disease were done. Among them, factor of sex is only appear statistically significant (P=0.001), but rest are not significant in statistically. Conclusion: Occurrence rates of SPMs were reported from 10% to 20% by precede study. In this study, occurrence rate of SPMs is 10.79% that is similar to results of precede research. In comparison of 5-yr survival rates of groups that develop SPMs or not, there is statistically significance between two groups. Present treatment modalities of SPMs are surgical operation, radiotherapy, chemotherapy and combination of these modalities. In choosing the treatment modality, we must consider the first treatment modality, region of primary disease, region of SPMs and general conditions of patient. Because development of SPMs have big effect on prognosis, prevention of SPMs must regard to important objective of treatments in patients of SCCa in oral cavity.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.6
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• pp.544-550
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• 2010

Purpose: The result of all malignant neoplasms including oral cancer is decided by long-term prognosis. However, until now, there are only a few reports about long-term prognosis of cancer secluded in the oral cavity. So, we investigated all patients that visited our clinic for oral squamous cell carcinoma (SCCa) for the last 10 years. From this survey, we hope to find important factors that influence prognosis of the disease. Patients and Methods: A retrospective study was performed for patients that visited the oral oncology clinic for oral cancers from Jan. 2001 to Feb. 2010. We selected the patients that were diagnosed with SCCa and received curative treatment. In these patients, we investigated basic epidemiology, smoking history, body mass index, recurrence rate, treatment methods, pathologic data and 5-yr survival rate. Results: There was a total of 185 patients (115 males, 70 females and mean age: 57.3 years) that visited the oral oncology clinic for oral SCCa. Areas of primary lesion were tongue (105 cases, 57%), lower gum (19 cases, 10%), floor of mouth (16 caess, 8%), retromolar trigone (12 cases, 6.5%), and buccal cheek (11 cases, 6%). Other involved areas were upper gum, palate, lip, and salivary glands-of 1 case each. The overall 5-year survival rate was 63.7%. The factors that influenced prognosis of the disease were stage of the disease, status of differentiation, recurrence, metastasis of cervical lymph node and age. Conclusion: The factors that influence prognosis of disease are stage of the disease, status of differentiation, recurrence, metastasis of cervical lymph node and age. To point out a current trend, the mean age of patients that developed oral cancer was lower than that of before. Secondly, the prevalence of oral cancer in non-smoker are on the rise. Thus, further studies on etiology and epidemiology should be done.