• Restorative Dentistry and Endodontics
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• v.43 no.4
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• pp.39.1-39.20
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• 2018

Magnetic resonance imaging (MRI) is an advanced diagnostic tool used in both medicine and dentistry. Since it functions based on a strong uniform static magnetic field and radiofrequency pulses, it is advantageous over imaging techniques that rely on ionizing radiation. Unfortunately, the magnetic field and radiofrequency pulses generated within the magnetic resonance imager interact unfavorably with dental materials that have magnetic properties. This leads to unwanted effects such as artifact formation, heat generation, and mechanical displacement. These are a potential source of damage to the oral tissue surrounding the affected dental materials. This review aims to compile, based on the current available evidence, recommendations for dentists and radiologists regarding the safety and appropriate management of dental materials during MRI in patients with orthodontic appliances, maxillofacial prostheses, dental implants, direct and indirect restorative materials, and endodontic materials.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.519-535
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• 1997

The responses of human pulp fibroblastic cells to Ga-As Semi-Conductor-Dens-Bio Laser (Frequency: 5 Hz~10,000 Hz Model: SD-101A RCA, U.SA)) were examined in vitro using pulp fibroblastic cells obtained from the pulp tissue of human tooth. The mitogenic effect of soft laser was assessed by measuring the MTT assay. The morphologic effect for soft laser showed under the scanning and transmission electron microscopy. The results as follows; 1. The mitogenic response of the soft laser was not observed until 4th time of radiation, while the mitogenic response at 4th time increased mitogenic effect by as much as 1.7 fold compared to the control value. 2. The mitogenic response of the soft laser on pulp fibroblast differ from the mitogenic response on other fibroblasts. 3. In scanning electron microscopic study, The microvilli of cell surface increased gradually with width and length after laser radiation, it demonstrate that development of microvilli have close connection with differentiation of cells. 4. Under the transmission electron microscope, The laser-treated cells maintained their elongated shape and a high degree of cellular polarization. The large cell body containing a well developed Golgi complex, a large number of profiles of rough endoplasmic reticulum, and great numbers of mitochondria. 5. The laser-treated cells maintained the long straight bundles of closely apposed microfilaments or individual filaments forming a cross-linked network. These findings suggest that the laser may have important roles in promotion of pulp healing and consequently may be useful for clinical application in pulp regenerative procedures.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.22 no.1
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• pp.87-94
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• 1992

The purpose of this study was to evaluate the effect of scatter radiation to dental x-ray film with long time-exposure in the different structures of the tooth, by using pinhole camera. For this study, pinhole camera, skull with tooth, and pocket dosimeter were used. The radiation with 70 and 90kVp and exposure time (minimum: 2.5 min., maximum 10 hrs.) was projected to the film in the pinhole camera. And density of the obtained x-ray film was measured with densitometer. In the intra-oral film taking, the amount of exposure of the scatter radiation affecting the thyroid gland area was measured with the dosimeter at the thyroid gland. The density of radiographs was compared in radiation projected with or without the metal cone of dental machine. The effect of the back scatter radiation to the film was also evaluated when the lead foil was removed. The obtained results were as follows: 1. A pinhole camera was a valuable device for locating the source of x-ray. 2. The scatter radiation affected the dental x-ray film when the radiation source was exposed. more than 5 hours'. In that case, the density of the scatter radiation could be observed visually. 3. The scatter radiation caused by short exposure of dental radiation didn't affect the diagnostic quality of the dental x-ray film. 4. The differences of densities between the tooth and the soft tissue according to exposure time showed 0.16 in 5 hours' exposure & 0.17 in 10 hours' exposure at 70 kVp & 0.12 in 5 hours' exposure & 0.13 in 10 hours' exposure at the 90kVp. 5. The differences of densities between the tooth and the soft tissue according to kVp showed no difference between 5 hours' exposure of tooth at 70 kVp and soft tissue at 90 kVp, but showed 0.05 high density in tooth when 10 hours' exposure at 90 kVp. 6. No difference of density was on radiographs taken with or without dental machine cone. 7. Back scatter radiation was recorded image of radiographs for only 3 min. 8. The amounts of the scatter radiation exposed to the thyroid gland in intraoral film taking were 1.12 mr in upper anterior, 0.55 mr in upper posterior, 2.75 mr in lower anterior, and 1.92 mr in lower posterior teeth.

• Imaging Science in Dentistry
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• v.39 no.3
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• pp.121-132
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• 2009

Purpose : To investigate the effects of 2-deoxy-D-glucose (2-DG) and quercetin (QCT) on gene expression of bone sialoprotein (BSP) and osteocalcin (OC) during the differentiation in irradiated MC3T3-E1 osteoblastic cells. Materials and Methods : When MC3T3-E1 osteoblastic cells had reached 70-80% confluence, cultures were transferred to a differentiating medium supplemented with 5 mM 2-DG or $10{\mu}M$ QCT, and then irradiated with 2, 4, 6, and 8 Gy. At various times after irradiation, the cells were analyzed for the synthesis of type I collagen, and expression of BSP and OC. Results : The synthesis of type I collagen in cells exposed to 2 Gy of radiation in the presence of 2-DG or QCT showed no significant difference compared with the control group within 15 days post-irradiation. When the cells were irradiated with 8 Gy, 2-DG facilitated the irradiation mediated decrease of type I collagen synthesis, whereas such decrease was inhibited by treating with QCT. During MC3T3-E1 osteoblastic cell differentiation, the mRNA expression of BSP and OC showed the peak value at 14 days and 21 days, respectively. 2-DG or QCT treatment alone decreased the level of BSP mRNA, but increased the OC mRNA level only at early time of differentiation (day 7). In the cells irradiated with 2, 4, 8 Gy, the mRNA expression of BSP and OC decreased at 7 days after the irradiation. The cells were treated with various dose of radiation in the presence of 2-DG or QCT, the mRNA level of both BSP and OC increased although this increase was observed at low dose of radiation (2 Gy) and at the early stage of differentiation. However, when the cells were exposed to 4, 6, or 8 Gy, the increase of BSP and OC mRNAs was detected only in cells co-incubated with QCT. Conclusion : This study demonstrates that 2-DG and QCT affect differently the expression of bone formation related factors, type I collagen, BSP, and OC in the irradiated MC3T3-E1 osteoblasic cells, according to the dose of radiation and the times of differentiation. Overall, the present findings suggest that 2-DG and QCT could have the regulatory roles as radiation-sensitizer and -protector, respectively.

• BMB Reports
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• v.34 no.2
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• pp.123-129
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• 2001

Cellular response to ionizing radiation is affected by cell types, radiation doses, and post-irradiation time. Based on the trypan blue dye exclusion assay in normal oral mucosal cells (OM cells), a 48 h post-irradiation was sufffcient and an adequate time point for the evaluation of radiation sensitivity Its $LD_{50}$ was approximately 1.83 Gy To investigate possible biomarkers useful for the biological radiodosimetry of normal epithelial cells (p53, c-fos, cyclin D1, cdc-2, pRb) EGF receptor phosphorylation and Erk activation were evaluated at different radiation doses and different post-irradiation times. From 0.5 Gy, p53 was accumulated in the nucleus of basal cells of the OM raft culture at 4 h post-irradiation and sustained up to 24 h post-irradiation, which suggests that radiation-induced apoptosis or damage repair was not yet completed. The number of p53 positive cells and biosynthesis of p53 were correlated with radiation doses. Both cyclin D1 and c-fos were only transiently induced within 1 h post-irradiation. Cyclin D1 was induced at all radiation doses. However, cfos induction was highest at 0.1 Gy, approximately 7.3 fold more induction than the control, whose induction was reduced in a reverse correlation with radiation dose. The phosphorylation pattern of cdc-2 and pRb were unaffected by radiation. In contrast to A431 tails overexpressing the EGF receptor approximately 8.5 fold higher than normal epithelial, the OM cells reduced the basal level of the EGF receptor phosphorylation in a radiation dose dependent fashion. In conclusion, among radiation-induced biomolecules, the p53 nuclear accumulation may be considered for the future development of a useful marker far biological radiodosimetry in normal epithelial tissue since it was sustained for a longer period and showed a dose response relationship. Specific c-fos induction at a low dose may also be an important finding in this study It needs to be studied further for the elucidation of its possible connection with the low dose radio-adaptive response.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.2
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• pp.331-338
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• 1999

Chemoradiation therapy used on pediatric oncology patients often causes dental developmental anomalies that affect future dental care. Defects noted include tooth and root agenesis, root thining and shortening, and localized enamel defects. The effect of radiotherapy usually are confined to the radiation site, but the effects of chemotherapy may be more wide spread because of its systemic distribution and structures and organs unrelated to the primary tumor may be affected. Many pediatric cancers are treated with a combination of radiation and multiagent chemotherapy to create synergic and additive effects. Dental treatment affected by chemoradiation damage to developing teeth includes orthodontic tooth movement, prosthetic abutment considerations, periodontal health, space maintenance, requirements for home fluoride regimens to protect hypomineralized areas, restoration options for hypoplastic/hypomineralized teeth, and endodontic procedures. The following case demonstrate chemoradiation therapy effects on the dental development.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.47 no.6
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• pp.471-475
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• 2021

Solitary plasmacytoma (SP) is an uncommon form of plasma cell neoplasm occurring intraosseously or in soft tissue and presents as a single mass of monoclonal plasma cells. SP in the maxillary sinus is rare and can be misdiagnosed as other maxillary sinus tumors. The essential examinations in patients with the initial diagnosis of plasmacytoma are bone marrow biopsy, serum and urine electrophoresis, and kappa/lambda ratio (κ:λ ratio) to rule out multiple myeloma (MM). Herein, a rare case of SP in the maxillary sinus treated by surgery and localized radiation is reported. At the 10-year follow-up examination, local recurrence or disseminated development of MM were not evident.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.1
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• pp.255-260
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• 1999

Purpose: The objective of this study was to evaluate the possibility of substitution of the zonography for the full-mouth periapical radiography in aspect of radiation protection. Materials and Methods: Rando phantom and LiF TLD chips were used for dosimetry. The absorbed doses at brain, skin above the TMJ. parotid gland. bone marrow in the mandibular body. and thyroid gland during the full-mouth periapical radiography. panoramic radiography. and zonography were measured. Resul ts: From the zonography. the absorbed doses to the brain. the skin over the TMJ. and the parotid gland were relatively high. but the absorbed doses to the bone marrow in the mandibular body and. especially. the thyroid gland were very low. Conclusion: The zonography can be an alternative to the full-mouth periapical radiography in aspect of radiation protection.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.23 no.2
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• pp.215-226
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• 1993

The purpose of this study was to investigate the effects of the low level irradiation on the mitotic index of the basal cells in the buccal pouch of hamsters{golden hamster: APG strain). After colchicine was administrated to the hamsters through the intraperitoneal, the low level radiation{5460mR) was exposed on the buccal pouch of hamsters. The mitotic index of the basal cells was estimated 2 hours after irradiation. The results were as follows: 1. The mean mitotic index of the control group was 4.32. 2. The mean mitotic index of the irradiated group was 2.46. 3. T-test of data in the irradiated group showed significant difference from the mitotic index in the control group. These results suggested the lowered mitotic index of the irradiated group resulted from the low level irradiation.

• The Journal of the Korean dental association
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• v.57 no.7
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• pp.392-402
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• 2019

The most important part of everyday root canal treatment is diagnosis about the morphology of tooth, root and root canal. Usually this procedure is performed by visual examination and radiographic (panoramic/periapical) examination. However, 2-dimentional radiography has several limitations such as imposition of anatomic structures including buccal/lingual root canals and distortion of images. Recently, owing to the increased interest in dental implant and affordable cost of CBCT equipment, CBCT has been introduced widely in local dental clinics. CBCT is characterized by their lower radiation dose and shorter exposure time than conventional CT scan, and ability of 3-dimentional reconstruction of the dento-alveolar structure. Also in endodontic field, the data from CBCT could be very helpful in diagnosing complex root canal anatomy, apical periodontitis, cause of failure and in determining treatment plan. However, there are some limitations such as radiation dose and artifact. Therefore, clinicians should know about indication, advantages and limitations of CBCT, and properly use it for successful root canal treatment to save the natural teeth.