• The Journal of Advanced Prosthodontics
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• 제6권6호
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• pp.427-433
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• 2014

PURPOSE. Surface color is one of the main criteria to obtain an ideal esthetic. Many factors such as the type of the material, surface specifications, number of firings, firing temperature and thickness of the porcelain are all important to provide an unchanged surface color in dental ceramics. The aim of this study was to evaluate the color changes in dental ceramics according to the material type and glazing methods, during the multiple firings. MATERIALS AND METHODS. Three different types of dental ceramics (IPS Classical metal ceramic, Empress Esthetic and Empress 2 ceramics) were used in the study. Porcelains were evaluated under five main groups according to glaze and natural glaze methods. Color changes (${\Delta}E$) and changes in color parameters (${\Delta}L$, ${\Delta}a$, ${\Delta}b$) were determined using colorimeter during the control, the first, third, fifth, and seventh firings. The statistical analysis of the results was performed using ANOVA and Tukey test. RESULTS. The color changes which occurred upon material-method-firing interaction were statistically significant (P<.05). ${\Delta}E$, ${\Delta}L$, ${\Delta}a$ and ${\Delta}b$ values also demonstrated a negative trend. The MC-G group was less affected in terms of color changes compared to other groups. In all-ceramic specimens, the surface color was significantly affected by multiple firings. CONCLUSION. Firing detrimentally affected the structure of the porcelain surface and hence caused fading of the color and prominence of yellow and red characters. Compressible all-ceramics were remarkably affected by repeated firings due to their crystalline structure.

• Journal of Periodontal and Implant Science
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• 제43권5호
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• pp.209-214
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• 2013

Purpose: To assess bony trabecular changes potentially caused by loading stress around dental implants using fractal dimension analysis. Methods: Fractal dimensions were measured in 48 subjects by comparing radiographs taken immediately after prosthesis delivery with those taken 1 year after functional loading. Regions of interest were isolated, and fractal analysis was performed using the box-counting method with Image J 1.42 software. Wilcoxon signed-rank test was used to analyze the difference in fractal dimension before and after implant loading. Results: The mean fractal dimension before loading ($1.4213{\pm}0.0525$) increased significantly to $1.4329{\pm}0.0479$ at 12 months after loading (P<0.05). Conclusions: Fractal dimension analysis might be helpful in detecting changes in peri-implant alveolar trabecular bone patterns in clinical situations.

• 대한치과기공학회지
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• 제30권2호
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• pp.9-16
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• 2008

The surface microstructural changes, mechanical properties and corrosion resistance of Ti-Pd alloys for dental biomaterials have been investigated. Ti, Ti-Pd alloys were melted in arc furnace and the corrosion resistance of Ti-Pd alloys was evaluated by anodic polarization test. The surface microstructural changes and mechanical properties of Ti-Pd alloys were analysed by scanning electron microscope and Vickers micro-hardness tester. The vickers hardnees of pure Ti improved by addition of Pd but Ti-25Pd alloy showed decreasing compared with Ti-15Pd. And anodic polarization and potentiostatic test were conducted in 5% HCl to quantify the resistance to corrosion with the addition of Pd, There was no significant difference in corrosion resistance between pure Ti, Ti-5Pd and Ti-15Pd alloy. However, Ti-25Pd alloy showed decreasing compared with pure Ti in corrosion resistance. From these results, it was concluded that newly formulated Ti-15Pd experimental alloy have adequate hardness and high corrosion resistance, and this alloy is promising candidate for a successful dental casting alloy.

• 대한치위생과학회지
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• 제4권1호
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• pp.65-77
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• 2021

Background: The purpose of the present study was to evaluate changes in the communication capabilities of dental hygiene students after completing a problem based learning (PBL) dental communication curriculum. With this information, we intend to gather the basic data necessary to stress the need for and value of an education in communication regarding dental hygiene. Methods: PBL-based education was provided to a total of 49 third-year dental hygiene students who took the dental communication class taught by the Department of Dental Hygiene at S University during the 2^nd semester of 2020. The relevant self-evaluation was modified, based on the aim of the present study, to refer to three basic key competencies related to the communication capabilities of dental hygienists. An assessment of dental communication competency was conducted by analyzing the changes in self-evaluations before and after completing the course, for each question, using a paired t-test. The statistical significance level was set at p < 0.05. Results: Analysis of core competencies before and after PBL-based dental communication education indicated that all competencies were significantly improved after education (p < 0.01). Conclusion: Dental hygiene students' dental communication skills increased significantly after completing PBL-based dental communication education. Therefore, a PBL-based dental communication curriculum is effective in improving dental communication skills for dental hygiene students.

• Journal of Oral Medicine and Pain
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• 제22권2호
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• pp.383-394
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• 1997

The purpose of this study was to examine the anatomic changes in the upper airway with a dental orthosis. the effectiveness and side effects of orthosis in the treatment of snoring and obstructive sleep apnea. To meet this puppose a dental orthosis, designed to increase the size of the upper airway by advancing the mandible, was used in 42 patients (30 M, 12 F), aged 29 - 69 years, to treat snoring and varying decrees of obstructive sleep apnea. Cephalometric study of anatomic featured was made with and without a dental orthosis, and the evaluation of the effectiveness and side effects of orthosis was done by questionnaires. The obtained results were as follows : 1. All subjects were habitual snorers and 32 patients comp1ained the loudness of snoring as severe as be heard outside of the patient's room. 2. According to the degree of respiratory distirbance index(RDI) and aprea index(Al) from the polysomnograph in 34 patient, mild obstructive sleep apnea patients were 5, moderate 6 and severe 16. 3. Various anatomic changes in the upper airway with denta1 orthosis were as follows : (1) More superioly positioned hyoid bone ( p<0.001) (2) Enlarged oropharyngeal (superior p<0.01, middle p<0.01. inferior p<0.01) and hypopharyngeal (P<0.05) airway space. 4. According to the results of the changes of clinical syptoms after the usage of the dental orthosis acquired from questionnaires, there was significant improvement in the frequently, the loudness and the severity of snoring, cessation of breathing and awakening from the difficulty of breathing during sleep. 5. The effectiveness and side effects of dental orthosis by questionnaires were as follows ; (1) Dental orthosis satisfied almost all the patients (68±20%). (2) Snoring was improved in all the patients (73±19%). (3) Obstructive sleep aphea was improved in all the patients (61 ± 37%) (4) Sleepiness in the daytime was significantly improved (61 ±37%). (5) The sleep quality was significantly improved (61±37%). (6) The discomfort of the dental orthosis was minor (33±18%) and no serious complications were observed. 6. The dental orthosis is an effective treatment for the symptom of snoring, and it can also effectively treat varying degrees of obstructive sleep apnea.

• 대한소아치과학회지
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• 제7권1호
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• pp.63-74
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• 1980

The purpose of this study is to analyze the width and length changes of the dental arches during the deciduous dentition period. 600 stone models of maxillary and mandibular arches obtained from the children aged 3, 4, or 5 years were under measurement. The results were as follows ; Arch widths and lengths differed with age, sex and arch. 1. * Widths of dental archs increase with age both in males and in females. * Lengths of dental arches decrease with age in females, but remain somewhat stable in males. 2. * The dental arches of males were wider than those of females in both the ant. and the post. section. * The dental arches of males were longer than those of females: ant.arch lengths were almost same, but post. arch lengths were longer in males. 3. * Upper arches were definitely wider and longer than lower arches.

• 대한치과의사협회지
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• 제10권5호
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• pp.273-276
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• 1972

The original sample in this investigation included 36 children around the age of eight (mean age:8 year-lmonth) at the beginning. Study casts were obtained and measured every 6 months in two years of longitudinal study period in order to observe the changes of maxillary dental arch as well as the eruptional status of the maxillary lateral incisors. The results were as follows.: 1) The length of upper dental arch was increased gradually during the examination period. 2) The width between maxillary first molars was increased gradually during the examination period. 3) Intercanine distance in upper dental arch was increased gradually and the increment was conspicuous immediately after the eruption of maxillary lateral incisors.

• 대한치과교정학회지
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• 제47권4호
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• pp.256-267
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• 2017

Objective: To evaluate transverse skeletal and dental changes, including those in the buccolingual dental axis, between patients with skeletal Class III malocclusion and facial asymmetry after bilateral intraoral vertical ramus osteotomy with and without presurgical orthodontic treatment. Methods: This retrospective study included 29 patients with skeletal Class III malocclusion and facial asymmetry including menton deviation > 4 mm from the midsagittal plane. To evaluate changes in transverse skeletal and dental variables (i.e., buccolingual inclination of the upper and lower canines and first molars), the data for 16 patients who underwent conventional orthognathic surgery (CS) were compared with those for 13 patients who underwent preorthodontic orthognathic surgery (POGS), using three-dimensional computed tomography at initial examination, 1 month before surgery, and at 7 days and 1 year after surgery. Results: The 1-year postsurgical examination revealed no significant changes in the postoperative transverse dental axis in the CS group. In the POGS group, the upper first molar inclined lingually on both sides (deviated side, $-1.8^{\circ}{\pm}2.8^{\circ}$, p = 0.044; nondeviated side, $-3.7^{\circ}{\pm}3.3^{\circ}$, p = 0.001) and the lower canine inclined lingually on the nondeviated side ($4.0^{\circ}{\pm}5.4^{\circ}$, p = 0.022) during postsurgical orthodontic treatment. There were no significant differences in the skeletal and dental variables between the two groups at 1 year after surgery. Conclusions: POGS may be a clinically acceptable alternative to CS as a treatment to achieve stable transverse axes of the dentition in both arches in patients with skeletal Class III malocclusion and facial asymmetry.

• 대한치과교정학회지
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• 제17권2호
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• pp.235-246
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• 1987

The purpose of this study was to detect out the changes occured during orthodontic treatment. The sample was consisted of 77 orthodontic patients. For this study 13 linear lengths and arch area were measured in maxilla, mandible respectively and were analyzed statistically. The results were as follows 1 The sequence of changes in the form and dimensions of dental arches following orthodontic treatment was as follows Class I malocclusion, Class III malocclusion, Class II malocclusion. 2 Changes in the form and dimensions of dental arches were greater in extraction cases than those of non-extraction cases 3 In comparison with maxilla and mandible on the amount of changes following orthodontic treatment in each malocclusion group, significant differences were greatest in class III malocclusion 4 In comparison with maxilla and mandible on the amount of changes following orthodontic treatment in extraction and non-extraction cases, significant differences were greater in extraction cases than those of non-extraction cases 5. The amount of changes during orthodontic treatment in extraction and non-extraction cases in male was not different from female's.

• Journal of Korean Dental Science
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• 제11권1호
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• pp.21-31
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• 2018

Occlusion may change spontaneously but dental treatment or trauma in the patients with temporomandibular disorders (TMDs) may also alter occlusion. This report presents three cases displaying occlusal changes. Review of literature emphasizes the significance of TMD treatment. Conservative treatment modalities such as counseling, medication, physical therapy and splint therapy may be selected as initial treatment options. Irreversible or invasive treatment, such as orthodontic, prosthodontic, and occlusal adjustment should not be attempted early. In case there is no response to conservative treatment, joint injection, muscle injection, arthrocentesis or arthroscopic surgery might be performed.