• The Journal of the Korean dental association
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• v.19 no.6 s.145
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• pp.535-540
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• 1981

In order to collect the basic data for planning school dental health programmes, the author had examined dental health conditions of 120 males and 120 females of Changgyung Primary School children in the first grade. The percentages of persons with conditions requiring immediate attention, toothbrushing times and daily frequency, df rate, df index, dt index, ft index, it index, DMF rate, DT index, MT index, FT index, IT index, DMFT index, percentages of persons with periodontal status in every of the four categories with soft deposits, calculus, intense gingivitis, and advanced periodontal involvement were calculated and evaluated. The obtained results were as follows: 1. Persons with requiring immediate attention was 7.1% of all the examined children. 2. The df rate was 88.3%, and df index was 3.4 teeth per person. And then the DMF rate was 17.1%, while DMFT index was 0.3 teeth per person. 3. As the periodontal status, the persons with soft deposits was 90.0% of children, calculus 26.3%, intense gingivitis 0.4%, and no advanced periodontal involvement. 4. Average toothbrushing frquency was 1.2 times in a day per person. But 71.5% of toothbrushing was performed before meals, while the others after meals.

• Restorative Dentistry and Endodontics
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• v.25 no.3
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• pp.359-370
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• 2000

The purpose of this investigation was to observe the viscoelastic properties of five commercial flowable(Aeliteflo, Flow it, Revolution, Tetric flow, Compoglass flow), three conventional hybrid(Z-100, Z-250, P-60) and two condensable(Synergy compact, SureFil) resin composites. A dynamic oscillatory shear test was done to evaluate the storage shear modulus (G'), loss shear modulus(G"), loss tangent(tan ${\delta}$) and complex viscosity(${\eta}^*$) of the resin composites as a function of frequency - dynamic frequency sweep test from 0.01 to 100 rad/s at $25^{\circ}C$ - by using Advanced Rheometric Expansion System(ARES). To investigate the effect on the viscosity of resin composites of filler volume fraction, the filler weight % and volume % were measured by means of Archimedes' principle using a pyknometer. The results were as follows 1. The complex viscosity ${\eta}^*$ of flowable resins was lower than that of hybrid resins and significant differences were observed between brands. The complex viscosity ${\eta}^*$ of condensable resins was higher than that of hybrid resins. The order of complex viscosity ${\eta}^*$ at ${\omega}$=10 rad/s was as follows, Surefil, Synergy compact, P-60, Z-250, Z-100, Aeliteflo, Tetric flow, Compoglass flow, Flow it, Revolution. The relative complex viscosity of flowable resins compared to Z-100 was 0.04~0.56 but Surefil was 30.4 times higher than that of Z-100. 2. The storage shear modulus G' and the loss shear modulus G" of flowable resins were lower than those of hybrid resins but those of condensable resins were higher. The patterns of the change of loss tangent, tan ${\delta}$, of resin composites with increasing frequency were significantly different between brands. The phase angles, ${\delta}$, ranged from $30.2{\sim}78.1^{\circ}$ at ${\omega}$=10 rad/s. 3. All composite resins represent pseudoplastic nature with increasing shear rate. 4. The complex shear modulus $G^*$ and the phase angle ${\delta}$ was represented by the frequency domain phasor form, $G^*({\omega})=G^*e^{i{\delta}}=G^*{\angle}{\delta}$. The locus of frequency domain phasor plots in a complex plane was a valuable method that represent the viscoelastic properties of composite resins. 5. There was no direct linear correlationship but a weak positive relation was observed between filler volume % or weight % and the viscosity of the resin composites.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.3
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• pp.239-251
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• 2023

The aim of this study is to evaluate the effect of noise-filtering earplugs on the hearing ability of dentists wearing them during noise-induced dental procedures. Pure tone audiometry and distortion product otoacoustic emission (DPOAE) tests were conducted at the initial visit and 1 year later to evaluate the hearing ability of the participants. As a result of the study, the pure tone average of the group wearing earplugs decreased significantly compared to the group not wearing earplugs, indicating an improvement in hearing. However, the signal-to-noise ratio of the DPOAE tests did not show a significant difference. These findings suggest that noise-filtering earplugs may have some effectiveness in preventing hearing loss. However, since the 1-year observation period may not be adequate to identify changes in hearing, a follow-up study with an extended follow-up period is necessary.

• The Journal of Advanced Prosthodontics
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• v.9 no.2
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• pp.93-98
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• 2017

PURPOSE. The purpose of this study was to compare the width ratio of maxillary anterior teeth according to age in the Korean population and to evaluate the maxillary central incisor width-to-length (W/L) ratio, given differences in age and gender. MATERIALS AND METHODS. Ninety-three Korean adults were divided into 3 groups (n = 31) by age. Group I was 20 - 39 years old, Group II was 40 - 59 years old, and Group III was over 60 years of age. After taking an impression and a cast model of the maxillary arch, the anterior teeth width ratio and central incisor W/L ratio were calculated from standard digital images of the cast models using a graph paper with a digital single lens reflex (DSLR) camera. The calculated ratios were compared among all groups and central incisor W/L ratio were analyzed according to age and gender. All comparative data were statistically analyzed with one-sample t-tests, one-way ANOVAs with Tukey tests, and independent t-tests. RESULTS. No significant differences in maxillary anterior teeth ratios were found among the age groups. The maxillary central incisor W/L ratios in Group III were the greatest and were significantly higher than those in the other groups. The central incisor W/L ratio of men was higher than that of women in Group II. CONCLUSION. Maxillary anterior teeth width ratios were similar in all age groups in the Korean population. The maxillary central incisor was observed as worn teeth in the group over 60 years of age, and a significant difference between genders was found in 40 to 50 year olds.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.35 no.6
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• pp.459-461
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• 2009

Polycythemia vera is one type of myeloproliferative disorder which occurs due to the clonal proliferation of hematopoietic stem cell related to the production of leukocyte and megakaryocyte which produces a little less than erythrocyte. Polycythemia vera has a peak incidence in the sixth decade of life with males affected slightly more frequently than females. Vasquez first described polycythemia vera as an autonomous erythrocytosis in 1892, and a further description, delineation of the disease process and a complete course outline were made in 1899, 1903 and 1938, respectively. Symptoms include pruritus, tinnitus, vertigo, gastrointestinal (GI) pain, and bleeding gums. Hyperuricemia and hyperuricosuria are present in about 40% of these patients. Complications are hemorrhage, thrombosis, post-polycythemic myeloid metaplasia, and leukemic transformation. In case of surgery, complications such as hemorrahge and thrombosis are highly likable to happen. We report a case of preoperative and postoperative of a 63-year-old male, who was diagnosed as oral cavity cancer in the mouth floor, with known history of hypertension and polycythemia vera. We considered that conservative management would be an advisable treatment for patients with uncontrolled systemic disease.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.18 no.2
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• pp.308-315
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• 1996

Osteoarthritis is a noninflammatory degenerative disease affecting the articular surfaces and is accompanied by remodeling of the underlying bone. The sympotms of osteoarthritis of the temporomandibular joint are pain in the joint and muscles of mastication, limitation. Osteoarthritis is generally accepted that several factors can contribute to the trauma, aging process, internal derangement and MPDS. Radiographic features of the osteoarthritis are seen flattening of joint, sclerosis on flattened area and osteophyte or anterior lipping. In the past, osteoarthritis was considered to self-limiting disease. Currently, synovial chondromembrane is part of the process of osteoarthritis secondary to trauma. Synovial chondromatosis is an uncommon disease of cartilaginous transformation of synovial membrane with formation of loose bodies within the joint space. The pathogenesis is more an active metaplastic than a neoplastic process. The cause of synovial chondromatosis is unknown. Although trauma and inflammation have all been cited as possible factors in tis pathogenesis. The clinical sign and symptoms are unilateral swelling of the joint region, pain in the joint area and crepitus seem to be the most reliable signs and symptoms. Radiographic evidence of loose bodies may or may not be present. This is a case report of 66 year old female with synovial chondromatosis, that is advanced disease of the osteoarthrits. We treated patient with surgical excision of lose bodies, diskectomy and synovectomy. The defected articular fossa area was reconstructed with temporalis fascia flap. The result was satisfactory.

• The Journal of Advanced Prosthodontics
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• v.4 no.2
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• pp.109-115
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• 2012

PURPOSE. The purpose of this clinical study was to evaluate the frequency and type of prosthetic complications in relation to type and properties of removable dentures and to investigate the influence of these complications and several data about the existing dentures on patient satisfaction. MATERIALS AND METHODS. Ninety nine patients (44 males and 55 females) wearing removable dentures have been included in the study. The complications of the patients were recorded; patient satisfaction was determined with a Visual Analog Scale (VAS) and the relationship of complications and patient satisfaction with several data about the dentures such as denture age, type of denture, centric relation and vertical dimension was investigated. Kruskal Wallis, Mann Whitney U and Chi square tests were used for statistical analyses. The results were evaluated statistically at a significance level of $P$ <.05. RESULTS. Need for addition of artificial teeth for dentures with correct centric relations was found to be significantly lower than dentures with wrong centric relations ($P$ <.01). Loss of retention, ulcerations and high vertical dimension affected the VAS chewing ability scores negatively and ulcerations affected the VAS phonation scores negatively ($P$ <.05). CONCLUSION. Considering the results of this study, it can be concluded that loss of retention, ulcerations and high vertical dimension caused patient dissatisfaction. Additionally, dentures with wrong centric relations caused need for addition of artificial teeth.

• Journal of Periodontal and Implant Science
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• v.38 no.4
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• pp.717-722
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• 2008

Purpose: The subepithelial connective tissue graft(SCTG) has been proven to be a highly predictable treatment modality for coverage of gingival recession. This case report was performed to evaluate the effect of various root coverage procedures using SCTG on gingival recession. Materials and Methods: Three patients presents with Miller's class I recession defect on the maxillary canine. Each other SCTG(coronally advanced flap, Bruno's Tech., envelope Tech.) were performed for root coverage. Clinical parameters assessed included recession depth, recession width, and keratinized gingival width. Measurements were taken at baseline and 2 months and follow up end. Results: The average of root coverage was 4 mm(100% of the pre-operative recession depth) at the 2, 5 months examination. The average increase of keratinized tissue between the baseline and the 2 months amounted to 3.2mm. Conclusion: Within the above results, various root coverage using SCTG is an effective procedure to Miller's class I recession defect and patient could be satisfied aesthetic requirement.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.3
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• pp.393-399
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• 2018

The aim of this review is to introduce about the issue of benzocaine and methemoglobinemia. Through blocking the pain during dental treatment, fear and anxiety of patients will be reduced. Thus, anesthetic agent containing benzocaine is commonly used while controlling the pain of patients during treatment. However, on May 28, 2018, the Ministry of Food and Drug Safety reported a medication safety report about restricting the use of benzocaine-containing agents in infants under 24 months and children. Also, they recommended a cautious use to adolescents and adults to prevent methemoglobinemia (MHb). This report was published due to an advice from Food and Drug Administration (FDA) on May 23, 2018. When using agents containing benzocaine, dentists must consider the probability of MHb and prepare for early diagnosis and appropriate action. Since 1930s, methylene blue is known to cure MHb patients. Therefore, the proper use of methylene blue for emergencies and diagnosis methods for early diagnosis of MHb should be familiar to dentists planning for the use of topical anesthetic agents. Dentists should be trained for emergency situation of MHb caused by the use of benzocaine.

• The Journal of Advanced Prosthodontics
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• v.3 no.1
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• pp.10-15
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• 2011

PURPOSE. This study investigated the influence of bone quality and surgical technique on the implant stability quotient (ISQ) value. In addition, the influence of interfacial bone quality, directly surrounding the implant fixture, on the resonance frequency of the structure was also evaluated by the finite element analysis. MATERIALS AND METHODS. Two different types of bone (type 1 and type 2) were extracted and trimmed from pig rib bone. In each type of bone, the same implants were installed in three different ways: (1) Compaction, (2) Self-tapping, and (3) Tapping. The ISQ value was measured and analyzed to evaluate the influence of bone quality and surgical technique on the implant primary stability. For finite element analysis, a three dimensional implant fixture-bone structure was designed and the fundamental resonance frequency of the structure was measured with three different density of interfacial bone surrounding the implant fixture. RESULTS. In each group, the ISQ values were higher in type 1 bone than those in type 2 bone. Among three different insertion methods, the Tapping group showed the lowest ISQ value in both type 1 and type 2 bones. In both bone types, the Compaction groups showed slightly higher mean ISQ values than the Self-tapping groups, but the differences were not statistically significant. Increased interfacial bone density raised the resonance frequency value in the finite element analysis. CONCLUSION. Both bone quality and surgical technique have influence on the implant primary stability, and resonance frequency has a positive relation with the density of implant fixture-surrounding bone.