• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.3
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• pp.310-320
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• 2022

This study aimed to evaluate the academic effectiveness of non-face-to-face classes in deciduous tooth morphology practice. Under the course name dental morphology, a total of 60 dental students took face-to-face classes while 55 pre-dental students took non-face-to-face classes. Students were required to submit their practical assignments after 5 weeks of practical classes. To evaluate the academic effectiveness of non-face-to-face classes, practical assignments were scored by an evaluator and compared with face-to-face classes using the Mann-Whitney U test and the chi-square test. The results showed that the practical score in face-to-face classes was 77.43 ± 5.97 and the practical score in non-face-to-face classes was 76.04 ± 5.83. There was no significant difference in the academic effectiveness of face-to-face classes compared to non-face-to-face classes in deciduous tooth morphology practice (p > 0.05). This study suggests that non-face-to-face classes on introductory practice such as the dental morphology course can provide comparable quality to the education taught in traditional face-to-face classes.

• Journal of Technologic Dentistry
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• v.34 no.2
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• pp.145-153
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• 2012

Purpose: The purpose of this study was to investigate to effect of the electro-polishing condition according to electrolyte temperature and current and polishing time on surface morphology and composition by scanning electron microscopy(SEM) and energy dispersive X-ray spectrometer(EDS) in dental casting Co-Cr-Mo alloys. Methods: 16 specimens were divided into 4 groups which have each 4 specimens. The size of specimens were 10mm wide and 5mm height. the electro-polishing of specimens are by polishing solution temperature and times in Co-Cr-Mo alloy by SEM and EDS analysis. Results: The results shows that most smooth surface is obtained when electro-polishing is performed at $49^{\circ}C$ for 30-40sec with electro gap of 10mm and 8 voltage. Conclusion: The morphologies of specimens after electro-polishing were scratch absent and significant between at $40^{\circ}C$ for 45sec and at $49^{\circ}C$ for 45sec.

• Restorative Dentistry and Endodontics
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• v.40 no.3
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• pp.241-248
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• 2015

Variation in root canal morphology, especially in maxillary first molar presents a constant challenge for a clinician in their detection and management. This case report describes the successful root canal treatment of a three rooted right maxillary first molar presenting with three canals each in the mesiobuccal and distobuccal roots and one canal in the palatal root. The clinical detection of this morphologic aberration was made using a dental operating microscope, and the canal configuration was established after correlating and computing the clinical, radiographic and cone-beam computed tomography (CBCT) scan findings. CBCT images confirmed the configuration of the canals in the mesiobuccal and distobuccal roots to be Al-Qudah and Awawdeh type (3-2) and type (3-2-1), respectively, whereas the palatal root had a Vertucci type I canal pattern. This report reaffirms the importance of careful examination of the floor of the pulp chamber with a dental operating microscope and the use of multiangled preoperative radiographs along with advanced diagnostic aids such as CBCT in identification and successful management of aberrant canal morphologies.

• The Journal of the Korean dental association
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• v.51 no.5
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• pp.255-264
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• 2013

Many concept of occlusion have been introduced in the past, but there isn't any generally accepted unified theory since a single occlusion theory cannot represent the natural perfection, especially considering the difference in clinical experience, the dynamic occlusion, and individual diversity in mastication pattern. NAT(Naturgemasse Aufwachstechnik)/NFR((Natur Funktionsgerechte Rekonstruktion) occlusion is not just a theory on occlusion, but a clinical occlusion that can be practically applied to clinical practice by providing dynamic occlusion adjusted to the individual mastication pattern and biomechanics. This report aims to provide a guide to a clinically biomechanical occlusion through the teamwork of both the dentist and the lab technician by introducing the NAT occlusion through following: reviewing the concept of occlusion in terms of morphology, its correlation with NAT/NFR occlusion, reviewing the limitation of conventional occlusion theories, and introducing the clinical application of NAT/NFR.

• Journal of Technologic Dentistry
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• v.30 no.2
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• pp.93-103
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• 2008

This research is designed for a consumer, not a supplier when it was designed. And the purpose is to present the reference data which is in order to improve the curriculum by analyzing the present subject of the curriculum. The research collected the curriculum for Dental Technology from a total of 20 schools --3-year colleges and 4-year colleges-- all in Korea. And we analyzed the average credits of subjects from students. As a result of this analysis, we get the conclusion below: 1. In a distribution which students answered about each subjects; Dental esthetic, Dental morphology I II, Dental morphology practice I II, and Seminar don't have many credits and mostly have a converged tendency in high points, according to the arithmetic mean of the major basis subjects. 2. In an analysis of the correlation which is based on the distinction of sex; Dental ceramics practice III, Medical terminology, Seminar, and The major basis subjects have a meaningful difference. (${\rho}$ < 0.05) 3. In an analysis of the correlation which is based on an age; The major basis subjects, and the application subjects have meaningful difference. (${\rho}$ < 0.05) 4. In a correlation coefficient between subjects; The correlation coefficient of the major application subjects is higher than the major basis subjects. According to the student ? t, we found that the level of significance is ${\rho}$ < 0.001, which is meaningful. We feel that Department of Dental Technology also highly need to design, and conduct focusing on a consumer who is working at the society, not a supplier. And we need to increase or decrease credits which have a meaningful difference.

• Restorative Dentistry and Endodontics
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• v.41 no.4
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• pp.322-331
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• 2016

Variation in the root and canal morphology of the maxillary first molars is quite common. The most common configuration is 3 roots and 3 or 4 canals. Nonetheless, other possibilities still exist. The presence of an additional palatal root is rather uncommon and has been reported to have an incidence of 0.06 - 1.6% in varying populations studied. Whenever two palatal roots exist, one of them is the normal palatal root, the other is a supernumerary structure which can be located either mesiolingually (radix mesiolingualis) or distolingually (radix distolingualis). This case report describes successful endodontic treatment of a maxillary first molar with radix mesiolingualis and radix distolingualis. Identification of this variation was done through clinical examination along with the aid of multiangled radiographs, and an accurate assessment of this morphology was made with the help of a cone-beam computed tomography imaging. In addition to the literature review, this article also discusses the epidemiology, classifications, morphometric features, guidelines for diagnosis, and endodontic management of a maxillary first molar with extra-palatal root.

• Journal of the Korean institute of surface engineering
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• v.49 no.3
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• pp.260-264
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• 2016

In this study, fractured surface morphology and mechanical properties of Ni-Cr-Mo alloys with various contents of Mo for dental material use have been evaluated by mechanical test. The alloys used were Ni-13Cr-xMo alloys with Mo contents of 4, 6, 8, and 10 wt.%, prepared by using a vacuum arc-melting furnace. Ni-13Cr-xMo alloys were used for mechanical test without heat treatment. The phase and microstructure of alloys using an X-ray diffraction (XRD) and optical microscopy (OM) were evaluated. To examine the mechanical properties of alloys according to microstructure changes, the tensile test and the hardness test were carried out using tensile tester. To understand the mechanism of Mo addition to Ni-Cr alloy on mechanical property, the morphology and fractured surfaces of alloys were investigated by field-emission scanning electron microscope (FE-SEM). As a result, 79Ni-13Cr-8Mo alloy was verified that the tensile strength and the hardness were better than others. Varying Mo content, the changes of microstructures of alloys were identified by OM and SEM and that of 79Ni-13Cr-8Mo alloy was proved fabricated well. Microstructures of alloys were changed depending on Mo content ratio. It has been observed that 8% alloy had the most suitable mechanical property for dental alloy.

• Restorative Dentistry and Endodontics
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• v.39 no.1
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• pp.45-50
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• 2014

Ambiguity in the root morphology of the mandibular second molars is quite common. The most common root canal configuration is 2 roots and 3 canals, nonetheless other possibilities may still exist. The presence of accessory roots is an interesting example of anatomic root variation. While the presence of radix entomolaris or radix paramolaris is regarded as a typical clinical finding of a three-rooted mandibular second permanent molar, the occurrence of an additional mesial root is rather uncommon and represents a possibility of deviation from the regular norms. This case report describes successful endodontic management of a three-rooted mandibular second molar presenting with an unusual accessory mesial root, which was identified with the aid of multiangled radiographs and cone-beam computed tomography imaging. This article also discusses the prevalence, etiology, morphological variations, clinical approach to diagnosis, and significance of supernumerary roots in contemporary clinical dentistry.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.38.1-38.10
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• 2016

Background: The aims of this study are to evaluate the lip morphology and change of lip commissure after mandibular setback surgery (MSS) for class III patients and analyze association between the amount of mandibular setback and change of lip morphology. Methods: The samples consisted of 14 class III patients treated with MSS using bilateral sagittal split ramus osteotomy. Lateral cephalogram and cone-beam CT were taken before and about 6 months after MSS. Changes in landmarks and variables were measured with 3D software program $Ondemand^{TM}$. Paired and independent t tests were performed for statistical analysis. Results: Landmarks in the mouth corner (cheilion, Ch) moved backward and downward (p < .005, p < .01). However, cheilion width was not statistically significantly changed. Landmark in labrale superius (Ls) was not altered significantly. Upper lip prominence angle (ChRt-Ls-$ChLt^{\circ}$) became acute. Landmarks in stomion (Stm), labrale inferius (Li) moved backward (p < .005, p < .001). Lower lip prominence angle (ChRt-Li-$ChLt^{\circ}$) became obtuse (p < .001). Height of the upper and lower lips was not altered significantly. Length of the upper lip vermilion was increased (p =< 0.01), and length of the lower lip vermilion was decreased (p < .05). Lip area on frontal view was not statistically significantly changed, but the upper lip area on lateral view was increased and change of the lower lip area decreased (p > .05, p < .005). On lateral view, upper lip prominent point (UP) moved downward and stomion moved backward and upward and the angle of Ls-UP-Stm ($^{\circ}$) was decreased. Lower lip prominent point (LP) moved backward and downward, and the angle of Stm-LP-Li ($^{\circ}$) was increased. Li moved backward. Finally, landmarks in the lower incisor tip (L1) moved backward and upward, but stomion moved downward. After surgery, lower incisor tip (L1) was positioned more superiorly than stomion (p < .05). There were significant associations between horizontal soft tissue and corresponding hard tissue. The posterior movement of L1 was related to statistically significantly about backward and downward movement of cheilion. Conclusions: The lip morphology of patients with dento-skeletal class III malocclusion shows a significant improvement after orthognathic surgery. Three-dimensional lip morphology changes in class III patients after MSS exhibited that cheilion moved backward and downward, upper lip projection angle became acute, lower lip projection angle became obtuse, change of upper lip area on lateral view was increased, change of lower lip area decreased, and morphology of lower lip was protruding. L1 was concerned with the lip tissue change in statistically significant way.

• Journal of Technologic Dentistry
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• v.20 no.1
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• pp.13-19
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• 1998

This study was performed to identify the current problem of The National Qualification Examination for Dental Technician and to provide suggestion for improvement of The National Qualification Examination System. This study was based on the questionaries answered by the professors in the department of dental technology of college and the members of Korea dental technician's society. The result could be summarized in the following. 1. The examination should be held not only in Seoul but in other areas simultaneously. 2. Prepartation of The National Qualification Examination should be entrusted to a committee composed of selected members of The Korea Dental Technician Association and selected members of professors in the department of dental technology. 3. The carrving practical examination should be continued and the method of grading should be change to ensure fairness, objectivity and balance. Specially colored wax can be used to prevent cheating in test. 4. The examination on the subject of "The Introduction Dental Anatomy" should be different for dental technicians and dental hygienists. And the subjects need to be divided into "Dental Morphology" and "Oral Anatomy".