• Imaging Science in Dentistry
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• 제49권1호
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• pp.19-26
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• 2019

Purpose: It has been proposed that using new prediction methods, such as neural networks based on dental data, could improve age estimation. This study aimed to assess the possibility of exploiting neural networks for estimating age by means of the pulp-to-tooth ratio in canines as a non-destructive, non-expensive, and accurate method. In addition, the predictive performance of neural networks was compared with that of a linear regression model. Materials and Methods: Three hundred subjects whose age ranged from 14 to 60 years and were well distributed among various age groups were included in the study. Two statistical software programs, SPSS 21 (IBM Corp., Armonk, NY, USA) and R, were used for statistical analyses. Results: The results indicated that the neural network model generally performed better than the regression model for estimation of age with pulp-to-tooth ratio data. The prediction errors of the developed neural network model were acceptable, with a root mean square error (RMSE) of 4.40 years and a mean absolute error (MAE) of 4.12 years for the unseen dataset. The prediction errors of the regression model were higher than those of the neural network, with an RMSE of 10.26 years and a MAE of 8.17 years for the test dataset. Conclusion: The neural network method showed relatively acceptable performance, with an MAE of 4.12 years. The application of neural networks creates new opportunities to obtain more accurate estimations of age in forensic research.

• 대한치과교정학회지
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• 제49권2호
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• pp.97-105
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• 2019

Objective: This study was performed to evaluate the accuracy and reliability of a newly designed method to achieve mandibular dental model superimposition, using voxel-based cone-beam computed tomography (CBCT) registration. Methods: Fourteen dry cadaveric mandibles and six teeth extracted from patients with severe periodontitis were used to establish 14 orthodontic tooth-movement models. The protocol consisted of two steps: in the first step, voxel-based CBCT mandible superimposition was performed; the reference comprised the external portion of the symphysis, extending to the first molar. The laser-scanned dental model image was then integrated with the CBCT image to achieve mandibular dental model superimposition. The entire process required approximately 10 minutes. Six landmarks were assigned to the teeth to measure tooth displacement, using tooth displacement on the superimposed laser-scanned mandibles as the reference standard. Accuracy was evaluated by comparing differences in tooth displacement based on the method and the reference standard. Two observers performed superimposition to evaluate reliability. Results: For three-dimensional tooth displacements, the differences between the method and the reference standard were not significant in the molar, premolar, or incisor groups (p > 0.05). The intraclass correlation coefficients for the inter- and intra-observer reliabilities of all measurements were > 0.92. Conclusions: Our method of mandibular dental model superimposition based on voxel registration is accurate, reliable, and can be performed within a reasonable period of time in vitro, demonstrating a potential for use in orthodontic patients.

• 한국콘텐츠학회논문지
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• 제12권10호
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• pp.357-364
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• 2012

치과용 스캐너를 기반으로 하는 디지털 모형은 기존의 전통적인 석고모형을 대체할 만큼 발전되고 있다. 본 연구의 목적은 디지털모형의 정확도와 신뢰도를 평가하고자 하였다. 상악의 전악모형을 주 모형으로 설정하여 주 모형으로부터 석고모형을 제작하였고(N=10), 치과용 백색광 스캐너를 이용하여 10개의 디지털모형 데이터를 채득하였다. 제작된 두 실험군(석고모형, 디지털모형)을 1명의 검사자가 2회에 걸쳐서 6곳의 계측지점을 측정하였다. 짝 표본 t-검정과 급내 상관계수을 이용하여 통계적인 분석을 하였다. 실험결과 측정값의 검사자 내 신뢰도는 급내 상관계수 결과 두 실험군 0.75에서 0.87의 범위를 보였다. 석고모형과 디지털 모형의 평균 오차값은 0.11mm에서 0.23mm의 범위를 나타내었고, 모든 계측지점에서 통계적으로 유의한 차이를 보였다(P<0.05). 본 실험결과 모든 계측지점에서 적정수준의 정확성은 확보되지 않았으나, 선행연구에 비추어 볼 때 임상적인 효용성은 검증되었다. 추가적으로 임상적인 사례를 통해 평가되어야 할 것으로 사료된다.

• 대한치과기공학회지
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• 제40권2호
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• pp.63-69
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• 2018

Purpose: The purpose of this study is to investigate the non-precious metal core materials used in the dental laboratory to fabricate the implant superstructure by CAD / CAM method. And to observe and compare the morphology and distribution of the osteoblasts in relation to implant osseointegration. Methods: In this study, the mandibular right first molar tooth model was selected as an international standard to produce a single core. Using this model, the impression was made with the silicone rubber, the tooth model was scanned, and a single core was designed and 5-axis milling was performed. The materials used were Cobalt-Chromium and Nickel-Chromium, and the cores for dental implant top structures were fabricated according to the procedures of the dental labs. After the fabrication, the marginal area of the core was separated and cell culture experiment was performed. The osteoblast cells used MC3T3-E1, which is currently widely used. For morphological analysis of osteoblasts, cells were posttreated and observed using CLSM (Confocal Laser Scanning Microscope) and compared. Results: The cell adhesion behavior of the specimen surface measured by CLSM was uniformly distributed in specimen A (Cobalt-Chromium) than in specimen B (Nickel-Chromium). The distribution and changes of the cells were different in the two specimens. Conclusion : It is possible to confirm that specimen A (Cobalt-Chromium) is suitable for the living body through adhesion and proliferation of osteoblasts related to implant osseointegration in the non-precious metal superstructure used after implantation. It is considered that it is preferable to use Co-Cr when fabricating the superstructure.

• 한국치위생학회지
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• 제21권3호
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• pp.255-269
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• 2021

Objectives: Subjective well-being is a representative indicator of quality of life. Work and life are not separated, and work itself is a part of life. The purpose of this study was to confirm the effect of psychological resources such as self-esteem, self-efficacy, GRIT, and resilience on the subjective career success and subjective well-being in dental hygienists. Methods: From November 12, 2020 to December 30, 2020, an online survey was conducted on 650 dental hygienists, and data from 630 were analyzed. For the analysis, independent two-sample t-test and one-way ANOVA were performed, and the confirmatory factor analysis and measurement model, construct validity, construct reliability, convergent validity, and discriminant validity were confirmed. This was verified using a structural equation model. SPSS 18.0 and AMOS 18.0 were used for the statistical analyses; p<0.05 were considered statistically significant. Results: The final model fit was found to be suitable. There was no significant difference in subjective career success with respect to the personal characteristics and career characteristics, except for total career and number of turnovers. There was no significant difference in subjective well-being according to personal characteristics and career characteristics. Psychological resources such as self-esteem, self-efficacy, GRIT, and resilience were significant for subjective career success (p<0.05, R²=0.637). Subjective career success was significant for subjective well-being (p<0.05, R²=0.378). Among the psychological resources, self-esteem had both direct and indirect effects on subjective well-being (p<0.05). Conclusions: Positive psychological resources, rather than external conditions, are an important prerequisite for subjective career success and subjective well-being. Thus, it is proven that work is a part of life.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제44권2호
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• pp.59-65
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• 2018

Objectives: This study aimed to optimize the thread depth and pitch of a recently designed dental implant to provide uniform stress distribution by means of a response surface optimization method available in finite element (FE) software. The sensitivity of simulation to different mechanical parameters was also evaluated. Materials and Methods: A three-dimensional model of a tapered dental implant with micro-threads in the upper area and V-shaped threads in the rest of the body was modeled and analyzed using finite element analysis (FEA). An axial load of 100 N was applied to the top of the implants. The model was optimized for thread depth and pitch to determine the optimal stress distribution. In this analysis, micro-threads had 0.25 to 0.3 mm depth and 0.27 to 0.33 mm pitch, and V-shaped threads had 0.405 to 0.495 mm depth and 0.66 to 0.8 mm pitch. Results: The optimized depth and pitch were 0.307 and 0.286 mm for micro-threads and 0.405 and 0.808 mm for V-shaped threads, respectively. In this design, the most effective parameters on stress distribution were the depth and pitch of the micro-threads based on sensitivity analysis results. Conclusion: Based on the results of this study, the optimal implant design has micro-threads with 0.307 and 0.286 mm depth and pitch, respectively, in the upper area and V-shaped threads with 0.405 and 0.808 mm depth and pitch in the rest of the body. These results indicate that micro-thread parameters have a greater effect on stress and strain values.

• 한국치위생학회지
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• 제15권5호
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• pp.841-847
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• 2015

Objectives: The purpose of the study was to investigate the satisfaction with instruction medium according to learner attitude and lecture mode in the dental hygiene students. Methods: A web-based self-reported questionnaire was complected by 155 dental hygiene students in Cheonan from May 26 to June 5, 2015. The questionnaire consisted of general characteristics of the subjects, school adaptation, interest to learn, effort to learn, faculty centered lecture, learner centered lecture, self-directed learning, motivation to learn, characteristics of each subject, and satisfaction with lecture mode. The study was approved by institutional review board (IRB) by Baekseok University. Chi-square test and multivariate logistic regression were used to evaluate the satisfaction to medium of instruction according to explanation factors. Results: The lecture mode, opportunity and motivation to learn, interest to learn and effort to learn were the significant factors to satisfaction with instruction medium. In multivariate logistic regression model, the adjusted odds ratio was 6.28 for the opportunity to learn and 4.87 for the interesting to learn. Conclusions: The satisfaction with instruction medium is the most important factor that decides the lecture mode and learner attitude including opportunity to learn and concern to learn.

• 치위생과학회지
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• 제17권6호
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• pp.516-522
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• 2017

본 연구는 조직문화유형, 치과위생사의 전문직정체성, 조직몰입 세 변인 간의 관계를 파악하고, 치과위생사의 조직몰입 수준에 영향을 미치는 요인을 파악하기 위해 수행되었다. 치과 병 의원에 근무하는 310명의 치과위생사를 대상으로 설문조사를 실시하여 다음과 같은 결과를 얻었다. 치과위생사가 인지하는 치과조직문화는 위계지향문화(3.39점)가 가장 높았으며, 업무지향문화(2.71점)가 가장 낮았다. 조직문화 중 혁신지향문화는 치과병원에 근무하는 경우와 3인 이상의 치과의사와 근무하는 경우에 치과의원에서 근무하는 경우나 1인 치과의사와 근무하는 경우보다 높았고, 전문학사인 경우보다 학사 이상인 경우에, 미혼자보다 기혼자가, 일반 치과위생사보다 실장급 치과위생사가 혁신지향문화를 더 높게 인식하는 것으로 나타났다(p<0.05). 관계지향문화는 1인 치과의사와 근무하는 경우(3.35점)와 실장급 치과위생사(3.43점)가 3인 이상의 치과의사와 근무하는 경우나 일반 치과위생사보다 높게 인식하고 있었다(p<0.05). 업무지향문화는 3인 이상의 치과의사와 근무하는 경우가 1인 치과의사와 근무하는 경우보다 유의하게 높았고, 치과병원에서 근무하는 경우가 치과의원에서 근무하는 경우보다 높게 나타났다(p<0.001). 조직몰입에 유의한 영향을 미치는 변수로는 관계지향문화(p<0.001)와 혁신지향문화(p=0.006)로 나타났다. 치과 내에 관계지향문화와 혁신지향문화의 형성을 유도하는 반면 위계지향문화를 감소시키는 것이 치과위생사의 조직몰입과 전문직정체성을 높이기 위한 전략이 될 수 있음을 시사한다.

• 치위생과학회지
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• 제5권1호
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• pp.1-5
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• 2005

본 연구는 치위생과에 재학중인 학생들의 윤리의식에 미치는 영향요인을 규명하여 윤리교육의 기초자료로 활용하고자 개별자기기입법에 의한 설문을 실시하여 다음과 같은 결론을 얻었다. 1. 기초윤리 의식수준에 연관된 변수는 치과윤리교육필요성인지, 임상실습경험, 직업윤리교육경험이었다. 치과윤리교육필요성을 인지한 학생들이 기초윤리 의식수준이 높았고, 임상실습경험과 직업윤리교육경험이 있는 학생들이 기초윤리에 관한 의식수준이 높은 것으로 나타났다. 2. 면허법규 의식수준은 치과위생사윤리강령개정을 알고 있는 학생일수록, 치과윤리교육필요성을 인지하고 있는 학생일수록 면허법규에 관한 의식수준이 높았다. 3. 전문가윤리 의식수준에 연관된 변수는 치과위생사윤리강령 개정인지, 치과윤리교육필요성인지, 윤리 의식을 배우는 역할모델이었다. 가장 큰 영향을 미친 변수는 치과위생사 윤리강령개정이었다. 4. 의사결정 의식수준은 치과윤리교육필요성을 인지하고 있는 학생일수록, 치과위생사윤리강령개정을 인지하고 있는 학생일수록, 임상실습경험이 있는 학생일수록, 윤리의식을 배우는 역할모델이 교회라고 응답한 학생일수록 의사결정에 관한 의식수준이 높았다. 5. 팀웍에 관한 의식수준은 치과위생사윤리강령개정인지와 치과윤리교육필요성인지이었다. 치과위생사윤리강령개정을 인지하고 있는 학생일수록, 치과윤리교육필요성을 인지하고 있는 학생일수록 팀웍에 관한 의식수준이 높았다. 6. 치과위생사윤리강령개정에 대해 모르고 있다고 응답한 학생은 88.4%이었고, 치과위생사 윤리강령개정을 알고 있는 학생의 전문가윤리 의식수준이 $3.44{\pm}0.23$으로 높았다 (p=0.000).

• 대한치과기공학회지
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• 제35권1호
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• pp.29-35
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• 2013

Purpose: The purpose of this study was to evaluate the validity of digital models fabricated by dental scannable stone. Methods: Twenty same cases of stone models(maxillary full arch) were manufactured. Intercanine distance, intermolar distance, two dental arch lengths(right, left), two diagonal of dental arch lengths(right, left) were measured for comparison. Each of ten stone models were measured by digital vernier calipers and scanned by dental scanner. Ten digital models were measured by CAD program. The mean(SDs) values were compared by a Mann-Whitney U test(${\alpha}$=0.05). Results: No statistically significant differences between the two groups were found at intermolar distance, dental arch length(right)(p>0.05). However, intercanine distance, dental arch length(left) and two diagonal of dental arch lengths(right, left) were statistically significant(p<0.05). Conclusion: Stone models fabricated by dental scannable stone showed larger than digital models.