• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.28 no.1
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• pp.59-71
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• 1998

The radiation-induced apoptosis was studied for two human cancer cell lines (KB cells, RPMI 2650 cells) and the human gingival fibroblast cell line (HGF-1 cells). The single irradiation of 2, 10, 20Gy was done with 241.5 cGylmin dose rate using the /sup 137/Cs MK cell irradiator. The cells were stained with propidium iodide and examined under the fluoro-microscope and assayed with the flow cytometry a day after irradiation. Also, the LDH assay was done to determine the amount of necrotic cells. The obtained results were as follows: 1. On the fluoro-microscope, many fragmented nuclei were detected in the KB, RPMI 2650, and HGF-1 cells after irradiation. 2. On the DNA content histogram obtained from the flow cytometry, the percentages of the pre-Gl peak of the control and 2, 10 and 20Gy irradiation group were 4.5, 55.0, 52.3, and 66.6％ on KB cells, 2.7, 3.3, 31.8, and 32.6％ on RPMI 2650 cells and 2.8, 21.8, 30.4, and 40.2％ on HGF-1 cells respectively. 3. The number of Gl-stage cells was abruptly decreased after 2Gy irradiation on KB cells and 10Gy irradiation on RPMI 2650 cells, But there was a slight decrease without regard to irradiation dose on HGF-1 cells. 4. There was no significantly different absorbance in extracellular LDH assay along the experimental cell lines.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.45 no.1
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• pp.21-28
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• 2019

Objectives: Osteoradionecrosis (ORN) is one of the most severe complications resulting from radiotherapy (RT) in patients with head and neck cancer (HNC). It is characterized by persistent exposed and devitalized bone without proper healing for greater than 6 months after a high dose of radiation in the area. To describe the profile and dental management of ORN in HNC patients undergoing RT in an oncological clinical research center. Materials and Methods: A retrospective descriptive study was performed to analyze dental records from HNC patients with ORN treated at an oncological clinical research center from 2013 to 2017. A total of 158 dental records for HNC patients were selected from a total of 583 records. Afterwards, this number was distributed to three examiners for manual assessments. Each examiner was responsible for selecting dental records that contained an ORN description, resulting in 20 dental records. Results: Mean patient age was 60.3 years with males being the most affected sex (80.0%). The most affected area was the posterior region of the mandible (60.0%) followed by the anterior region of the mandible (20.0%) and the posterior region of the maxilla (10.0%). The factors most associated with ORN were dental conditions (70.0%) followed by isolated systemic factors (10.0%) and tumor resection (5.0%). There was total exposed bone closure in 50.0% of cases. The predominant treatment was curettage associated with chlorhexidine 0.12% irrigation (36.0%). Conclusion: Poor dental conditions were related to ORN occurrence. ORN management through less invasive therapies was effective for the closure of exposed bone areas and avoidance of infection.

• Imaging Science in Dentistry
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• v.50 no.4
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• pp.291-298
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• 2020

Purpose: The detection and exact localization of penetrating foreign bodies are crucial for the appropriate management of patients with dentoalveolar trauma. This study compared the efficacy of cone-beam computed tomography (CBCT) and spiral computed tomography (CT) scans for the detection of different foreign bodies composed of 5 frequently encountered materials in 2 sizes. The effect of the location of the foreign bodies on their visibility was also analyzed. Materials and Methods: In this in vitro study, metal, tooth, stone, glass, and plastic particles measuring 1×1×1 mm and 2×2×2 mm were prepared. They were implanted in a sheep's head in the tongue muscle, nasal cavity, and at the interface of the mandibular cortex and soft tissue. CBCT and spiral CT scans were taken and the visibility of foreign bodies was scored by 4 skilled maxillofacial radiologists who were blinded to the location and number of foreign bodies. Results: CT and CBCT were equally accurate in visualizing metal, stone, and tooth particles of both sizes. However, CBCT was better for detecting glass particles in the periosteum. Although both imaging modalities visualized plastic particles poorly, CT was slightly better for detecting plastic particles, especially the smaller ones. Conclusion: Considering the lower patient radiation dose and cost, CBCT can be used with almost equal accuracy as CT for detecting foreign bodies of different compositions and sizes in multiple maxillofacial regions. However, CT performed better for detecting plastic particles.

• Journal of Korean Dental Science
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• v.16 no.1
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• pp.9-22
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• 2023

Xerostomia is defined as the subjective complaint of dry mouth with or without hyposalivation, which is insufficient salivary secretion from salivary gland. Xerostomia can lead to multiple oral symptoms such as dental caries, halitosis, burning mouth syndrome, and oral candidiasis, which can significantly impact the well-being of patients, especially in geriatric patients who may already have compromised health. Clinical findings of xerostomia include decreased salivary flow and alterations in salivary composition. These changes can lead to various oral health problems such as dental caries, periodontitis, swallowing and speaking difficulties, taste disturbances, halitosis, mucosal diseases, and burning mouth syndrome. Recognizing these clinical manifestations is essential for early diagnosis and appropriate management. Although several reasons and risk factors have been suggested for xerostomia such as aging, chemo-radiation therapy, systemic disease, and Sjögren's syndrome, the polypharmacy is recently highlighted especially in elderly patients. Understanding the etiology and risk factors associated with xerostomia is crucial for effective management. To manage xerostomia patients, a multidisciplinary guideline should be established beyond dental care. Through this literature review, we summarized consideration for diagnostic, therapeutic, nursing essentials for the clinical guideline. By addressing the underlying causes and implementing appropriate treatment strategies, healthcare professionals can improve the quality of life for individuals suffering from xerostomia.

• The Journal of the Korean dental association
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• v.52 no.3
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• pp.139-146
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• 2014

The quality assurance program of a panoramic radiography is been discussed in two ways: phantom image tests and clinical image quality assurance tests. Methods and standards of each of the test are presented, which efforts guarantee a proper quality of image, improve standard of dental care and decrease radiation exposure.

• The Journal of the Korean dental association
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• v.56 no.7
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• pp.385-390
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• 2018

Laser means "Light amplification by stimulated emission of radiation". Laser have unique characteristics according to wavelength. Wavelenth of Waterlase is 2780nm and it can be absorbed to water and hydroxyapatite. When laser is applied to some material, its temperature goes up due to laser's energy. But in dental treatment high temperature is not good for teeth. High temperature can make dental pulp and bone necrosis. Waterlase can be absorbed to water droplet, so when it burst, it can cut soft and hard tissue without raising temperature. so it is so proper to dental treatment.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.144-150
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• 2008

Multimodal cancer therapy including surgery, chemotherapy, and radiotherapy could not only improve the prognosis of malignancy but also reduce the dosage and toxicity of cancer drug for treatment of malignant tumor. The effects of radiotherapy are generally localized, additive, and accumulative, and depend on dosage, site and cell sensitivity. However, in growing individuals, the dental and skeletal sequelae to radiotherapy result in dental or facial abnormalities that are irreversible : arrested root development, disturbances in enamel formation, microdontia, anodontia, altered tooth eruption and mandibular or maxillary hypoplasia. Especially, the teeth which are developing is affected according to the stage. We report three cases of developmental disturbance of permanent teeth after radiotherapy. These children had received radiotherapy for malignant tumor at the age of 3 to 4 years, in which root hypoplasia, short tapered root and early apex closure were observed. For the management of radiation caries and radiotherapy-related teeth, periodic recall check and oral hygiene instruction are required.

• The Korean Journal of Nuclear Medicine
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• v.34 no.2
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• pp.144-153
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• 2000

Purpose: The purpose of this study was to evaluate the relationship between radiation-induced activation of DNA repair genes and radiation induced apoptosis in A431 cell line. Materials and Methods: Five and 25 Gys of gamma radiation were given to A431 cells by a Cs-137 cell irradiator. Apoptosis was evaluated by flow cytometry using annexin V-fluorescein isothiocyanate and propidium iodide staining. The expression of DNA repair genes was evaluated by both Northern and Western blot analyses. Results: The number of apoptotic cells increased with the increased radiation dose. It increased most significantly at 12 hours after irradiation. Expression of p53, p21, and hRAD50 reached the highest level at 12 hours after 5 Gy irradiation. In response to 25 Gy irradiation, hRAD50 and p21 were expressed maximally at 12 hours, but p53 and GADD45 genes showed the highest expression level after 12 hours. Conclusion: Induction of apoptosis and DNA repair by ionizing radiation were closely correlated. The peak time of inducing apoptosis and DNA repair was 12 hours in this study model. hRAD50, a recently discovered DNA repair gene, was also associated with radiation-induced apoptosis.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.6
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• pp.379-391
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• 2003

The present study was undertaken to evaluate bone regenerative capacity around titanium screw implants placed in irradiated rat's tibiae. At one week after single 15-Gy dose irradiation, miniaturized titanium screw implants were inserted into anterior aspect of the upper tibia of rats weighing 200-250g. Seventy rats were involved: 35 rats were control and 35 rats radiation group. The rats were killed at different intervals as 1, 2, 3, 4, 6, 8, 12 weeks after implantation for histologic observation, histomorphometric analysis and immunohistochemical study with fibronectin and CD34 antibody. 1. Histologically, various stages of bone maturation and ossification can be seen at 4 weeks and regenerated bone close to edges demonstrates more advanced calcification, and network of new bone are well formed at 12 weeks in non-irradiated group. In contrast, active bone formation with increased contact of newly formed bone to implant surface was noted at 4 weeks and a significant amount of new bone formation and bone-implant contact is oberved at 12 weeks in irradiated group. 2. Histomorphometrical analysis confirmed these histologic findings. A significant difference in implant-bone contact and bone density was measured between the control and radiation group. Mean MBD was 62.2% in control group and 27.5% in radiation group, mean MBIC was 86.6% in control group and 47.7% in radiation group, and mean TBIC was 87.3% in control group and 45.6% in radiation group at 12 weeks after implantation. 3. In immunohistochemical study with fibronectin and CD34, radiation reduced hematopoietic progenitor cells severely and disturbed differentiation of osteoblast in bone marrow. The results of this study revealed bone healing capacity around implant after radiation therapy was severely impaired and irradiation reduces the capacity for osseointegration of titanium implants. Many factors including radiation dose, period between radiation and implantation, bone quality, time elapse between first and second surgery, type of prosthetics and hyperbaric oxygen therapy must be considered carefully in postradiation implantation.

• Journal of Radiation Protection and Research
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• v.25 no.1
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• pp.37-43
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• 2000

Protective effect of medicinal plant extracts against oxidative stress were screened in this study. Methanol extracts from 48 medicinal plants, which were reported to have antioxidative or anti-inflammtory effect were prepared and screened for their protective activity against chemically-Induced and radiation-induced oxidative stress by using MTT assay. Thirty three samples showed protective activity against chemically-induced oxidative stress in various extent Among those samples, extract of Glycyrrhiza uralensis revealed the strongest activity (25.9% at $100{\mu}g/m{\ell}$) with relatively lower cytotoxicity. Seven other samples showed higher than 20% protection at $100{\mg}g/m{\ell}$. These samples were tested for protection activity against radiation-induced oxidative stress. Methanol extract of Alpina officinarum show the highest activity (17.8% at $20{\mu}g/m{\ell}$). Five fractions were prepared from the each 10 methanol extracts which showed high protective activity against oxidative stress. Among those fraction samples butanol fractions of Areca catechu var. dulcissima and Spirodela polyrrhiza showed the highest protective activities (78.8% and 77.2%, respectively, at $20{\mu}g/m{\ell}$).