• Imaging Science in Dentistry
• /
• 제51권4호
• /
• pp.399-406
• /
• 2021

Purpose: This in vitro study measured and compared 3 intraoral scanners' accuracy (trueness and precision) with different span lengths. Materials and Methods: Three master casts were prepared to simulate 3 different span lengths (fixed partial dentures with 3, 4, and 5 units). Each master cast was scanned once with an E3 lab scanner and 10 times with each of the 3 intraoral scanners (Trios 3, Planmeca Emerald, and Primescan AC). Data were stored as Standard Tessellation Language (STL) files. The differences between measurements were compared 3-dimensionally using metrology software. Data were analyzed using 1-way analysis of variance with post hoc analysis by the Tukey honest significant difference test for trueness and precision. Statistical significance was set at P<0.05. Results: A statistically significant difference was found between the 3 intraoral scanners in trueness and precision (P<0.05). Primescan AC showed the lowest trueness and precision values(36.8 ㎛ and 42.0 ㎛;(39.4 ㎛ and 51.2 ㎛; and 54.9 ㎛ and 52.7 ㎛) followed by Trios 3 (38.9 ㎛ and 53.5 ㎛; 49.9 ㎛ and 59.1 ㎛; and 58.1 ㎛ and 64.5 ㎛) and Planmeca Emerald (60.4 ㎛ and 63.6 ㎛; 61.3 ㎛ and 69.0 ㎛; and 70.8 ㎛ and 74.3 ㎛) for the 3-unit, 4-unit, and 5-unit fixed partial dentures, respectively. Conclusion: Primescan AC had the best trueness and precision, followed by Trios 3 and Planmeca Emerald. Increasing span length reduced the trueness and precession of the 3 scanners; however, their values were within the accepted successful ranges.

• The Journal of Advanced Prosthodontics
• /
• 제13권6호
• /
• pp.351-360
• /
• 2021

PURPOSE. The aim of this study was to evaluate the efficiency of occlusal and interproximal adjustments of single implant crowns (SIC), comparing a digital cast-free approach (CF) and a protocol using 3D printed casts (PC). MATERIALS AND METHODS. A titanium implant was inserted at position of lower right first molar in a typodont. The implant position was scanned using an intraoral scanner and SICs were fabricated accordingly. Ten crowns (CF; n = 10) were subject to a digital cast-free workflow without any labside occlusal and interproximal modifications. Ten other identical crowns (PC) were adjusted to 3D printed casts before delivery. All crowns were then adapted to the testing model, simulating chair-side adjustments during clinical placement. Adjustment time, quantity of adjustments, and contact relationship were assessed. Data were analyzed using SPSS software (P < .05). RESULTS. Median and interquartile range (IQR) of clinical adjustment time was 02:44 (IQR 00:45) minutes in group CF and 01:46 (IQR 00:21) minutes in group PC. Laboratory and clinical adjustment time in group PC was 04:25 (IQR 00:59) minutes in total. Mean and standard deviation (±SD) of root mean squared error (RMSE) of quantity of clinical adjustments was 45 ± 7 ㎛ in group CF and 34 ± 6 ㎛ in group PC. RMSE of total adjustments was 61 ± 11 ㎛ in group PC. Quality of occlusal contacts was better in group CF. CONCLUSION. Time effort for clinical adjustments was higher in the cast-free protocol, whereas quantity of modifications was lower, and the occlusal contact relationship was found more favourable.

• The Journal of Advanced Prosthodontics
• /
• 제16권3호
• /
• pp.139-150
• /
• 2024

PURPOSE. The purpose of this diagnostic study was to assess the accuracy and time efficiency of a digital method to draw the denture foundation extension outline on preliminary casts compared with the conventional technique. MATERIALS AND METHODS. A total of 28 preliminary edentulous casts with no anatomical landmarks were digitized using a laboratory scanner. The outlining of the entire basal seat of the denture was performed on preliminary casts and digitized. Casts with no extension outline were digitized and outlines were drawn using software (DWOS, Straumann). The accuracy of the extension outlined between both techniques was evaluated in the software (GOM Inspect; GOM GmbH) by file superimposition. Specificity and sensitivity tests were applied to measure accuracy. The paired t-test (95% CI) was used to compare the mean total area and the working time. RESULTS. The accuracy ranged from 0.57 to 0.92. The buccal and labial frenulum showed a lower value in the maxilla (0.57); while the area between the retromolar pad and buccal frenulum (0.64) showed a lower score in the mandible. The maxillary denture foundation and the working time for both arches were significantly longer for the digital method (P < .001). CONCLUSION. The denture foundation extension outline exhibited a sufficiently excellent accuracy for the digital method, except for the maxillary anterior region. However, the digital method required a longer working time.

• 대한치과보철학회지
• /
• 제59권1호
• /
• pp.27-35
• /
• 2021

목적: 현재 임상에서 스캔바디를 이용한 임플란트의 디지털 인상이 활용되고 있으나 스캔바디의 형태에 따른 스캔의 정확도에 대한 연구는 부족한 실정이다. 본 연구의 목적은 구내 스캔바디의 형태에 따른 스캔의 정확도를 비교하고, 구강 내 노출 높이에 따른 라이브러리 중첩 정확도를 비교하기 위함이다. 재료 및 방법: 덴티폼 상에서 36번 치아를 삭제 후 모델 스캐너로 스캔하여 3D 프린터로 주모형을 출력하였다. 첫 번째 실험으로 세 종류(A, B, C)의 구내 스캔바디를 준비하여 각 그룹마다 다음과 같은 실험을 하였다: 36번 부위에 임플란트를 이상적인 위치로 식립 후 스캔바디를 15 N으로 체결하였다. 스캔바디가 체결된 주모형을 모델 스캐너로 스캔하여 master reference file (대조군)을 STL (Standard Tessellation Language) file로 생성하였다. 이후 구강 스캐너로 10회의 연속적인 스캔을 시행하여 10개의 STL file (실험군)을 생성하였다. 3D 측정 소프트웨어를 이용하여 대조군과 실험군들의 STL file들을 중첩한 후 좌표계 상에서 다음과 같은 값들을 도출하였다: 1) 스캔바디 상 특정 point의 거리 편차 2) 스캔바디 장축의 각도 편차. 두 번째 실험으로는 스캔바디의 구강내 노출 높이에 따른 라이브러리 중첩 정확도를 비교하기 위해 스캔바디 스캔 데이터를 7, 4.5, 2.5, 1.5, 1.0, 0.5 mm 총 6 가지 높이로 준비하여 라이브러리 파일과 중첩하였다. 전체가 노출된 7 mm 데이터를 대조군으로 하여 거리 편차와 각도 편차를 계산하였다. 결과: 첫번째 실험에서 A, B 스캔바디 간(P = .278), B, C 스캔바디 간(P = .568), C, A 스캔바디 간(P = .711) 스캔 파일의 거리 편차 모두 유의한 차이가 나타나지 않았다. A, B 스캔바디 간(P= .568), B, C 스캔바디 간(P = .546), C, A 스캔바디 간(P = .112) 스캔 파일의 각도 편차 또한 모두 유의한 차이가 나타나지 않았다. 또한 스캔바디는 구강 내 노출 높이가 높은 실험군(GH, Gingival Height = 4.5)의 라이브러리 중첩 정확도가 높이가 낮은 실험군(GH = 0.5)보다 통계적으로 유의하게 높았다 (P < .05). 결론: 스캔바디의 각기 다른 형태에 따른 스캔 정확도는 유의한 차이가 없었으며, 스캔바디의 구강 내 노출 높이에 따라 라이브러리 중첩의 정확도는 증가한다. 추후 in vivo 환경에서 더 다양한 형태의 스캔바디를 이용한 후속연구가 필요할 것이다.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제23권4호
• /
• pp.306-323
• /
• 2001

종양발생에서 유전자 발현을 확인하고 profile 변화를 monitor하는 것은 병리학적 변화의 원인뿐 아니라 질병탐지와 진료의 새로운 목표를 확인하기 위한 새로운 기회를 제공해준다. cDNA microarray는 수천개의 유전자 발현을 동시에 연구할 수 있는 최신의 방법으로 피부, 유방, 간을 비롯한 다른 인체장기에서는 일부 이루어졌으나 array를 이용해 타액선 종양 연구에서는 전혀 이루어지지 않았다. 인간의 타액선 세포의 악성형질전환을 조절하는 분자적 상태를 연구하기 위해 본 연구는 약 2,000개의 유전자가 print된 cDNA microarray를 이용하여 인간 타액선 도관상피세포주(HSG)와 악하선에서 기원한 미분화 선암종(SGT)간에 비교연구를 하였다. Cy3와 Cy5 dye로 각각의 세포주에서 얻은 RNA와 reciprocal hybridize시키고 GenePix 4000 scanner로 스캔하고 GenePix Pro로 분석한 후 log2로 평균발현비율을 전환시켜 최소 2배이상의 발현을 보이는 유전자를 분석대상으로 하였다. 90%이상의 유전자가 비슷한 발현을 보였으며 2배이상의 발현을 보이는 경우 HSG가 SGT에 비해 72개 유전자가, SGT가 HSG에 비해 111개의 유전자 발현이 up-regulation되어 총 10%미만의 발현차이를 보였고 반복된 hybridization 으로부터 얻은 선택된 spot의 Pearson 상관계수는 -0.85이였다. HSG에서는 6번 p 염색체에서 과발현되는 유전자가 가장 많았고, SGT에서는 11번 q 염색체에서 가장 많았는데 HSG에서는 SGT에 비해 9, 13, 17, 18, 20, 21, 22염색체에서 과발현 되는 유전자 수가 많았고, SGT에서는 HSG에 비해 2, 7, 10, 15 염색체에서 유전자 발현 증가가 관찰되었다. HSG와 SGT간의 유전 발현을 기능별로 분석한 결과 몇 가지 주요 경로가 세포악성에 관련됨을 발견하였고, 타액선 도관상피세포에서 선암종을 구별하는데 기여하는 관련된 몇종의 과다 발현된 유전자를 찾았는데 전사인자, 성장인자 및 수용기, 세포골격 및 세포외기질 단백, 세포내 신호전달조절자 및 인자, 세포표면 항원등의 그룹으로 분류할 수 있었다. 따라서 이러한 microarray를 이용한 분자학적 표지자 연구가 악성 타액선 종양 발생과정에서 큰 도움을 줄 수 있을 뿐 아니라 유전자 조절에 의한 진단, 예후, 치료에서의 정확성을 개선시킬 수 있으리라 여겨진다.

• 한국치위생학회지
• /
• 제13권6호
• /
• pp.909-916
• /
• 2013

Objectives : The purpose of this study was to investigate the perceptions of dental hygienists toward digital dentistry. Methods : The subjects were 393 dental hygienists in Daegu Gyeongbuk. A total of 380 data were analyzed except the incomplete questionnaires. Data were analyzed by descriptive statistics, chi-square test, t-test, one-way ANOVA using SPSS version 18.0. Results : 1. Difference of perception by general characteristics was affected by age, academic background, working career, and married. 2. Difference of perception by utilization of digital facilities was affected by digital camera, CAD/CAM system, oral scanner, and computer system. 3. Difference of perception by digital education experience and intention of participation was affected by stronger intention to participate in digital education and practical exercise. Digital X-ray system and CAD/CAM system were the must-be equipment in education. Conclusions : Utilization of digital dentistry is the motive for education experience in dental hygienists.

• Journal of Periodontal and Implant Science
• /
• 제45권1호
• /
• pp.8-13
• /
• 2015

Purpose: The aim of this study was to evaluate the transfer of different occlusal forces in various skeletal malocclusions using finite element analysis (FEA). Methods: Three representative human cone-beam computed tomography (CBCT) images of three skeletal malocclusions were obtained from the Department of Orthodontics, Yonsei University Dental Hospital, Seoul, South Korea. The CBCT scans were read into the visualization software after separating bones and muscles by uploading the CBCT images into Mimics (Materialise). Two separate three-dimensional (3D) files were exported to visualize the solid morphology of skeletal outlines without considering the inner structures. Individual dental impressions were taken and stone models were scanned with a 3D scanner. These images were integrated and occlusal motions were simulated. Displacement and Von Mises stress were measured at the nodes of the FEA models. The displacement and stress distribution were analyzed. FEA was performed to obtain the 3D deformation of the mandibles under loads of 100, 150, 200, and 225 kg. Results: The distortion in all three skeletal malocclusions was comparable. Greater forces resulted in observing more distortion in FEA. Conclusions: Further studies are warranted to fully evaluate the impact of skeletal malocclusion on masticatory performance using information on muscle attachment and 3D temporomandibular joint movements.

• 대한치과교정학회지
• /
• 제47권2호
• /
• pp.108-117
• /
• 2017

Objective: To investigate the effects of frontal facial type (FFT) and sex on preferred chin projection (CP) in three-dimensional (3D) facial images. Methods: Six 3D facial images were acquired using a 3D facial scanner (euryprosopic [Eury-FFT], mesoprosopic [Meso-FFT], and leptoprosopic [Lepto-FFT] for each sex). After normal CP in each 3D facial image was set to $10^{\circ}$ of the facial profile angle (glabella-subnasale-pogonion), CPs were morphed by gradations of $2^{\circ}$ from normal (moderately protrusive [$6^{\circ}$], slightly protrusive [$8^{\circ}$], slightly retrusive [$12^{\circ}$], and moderately retrusive [$14^{\circ}$]). Seventy-five dental students (48 men and 27 women) were asked to rate the CPs ($6^{\circ}$, $8^{\circ}$, $10^{\circ}$, $12^{\circ}$, and $14^{\circ}$) from the most to least preferred in each 3D image. Statistical analyses included the Kolmogorov-Smirnov test, Kruskal-Wallis test, and Bonferroni correction. Results: No significant difference was observed in the distribution of preferred CP in the same FFT between male and female evaluators. In Meso-FFT, the normal CP was the most preferred without any sex difference. However, in Eury-FFT, the slightly protrusive CP was favored in male 3D images, but the normal CP was preferred in female 3D images. In Lepto-FFT, the normal CP was favored in male 3D images, whereas the slightly retrusive CP was favored in female 3D images. The mean preferred CP angle differed significantly according to FFT (Eury-FFT: male, $8.7^{\circ}$, female, $9.9^{\circ}$; Meso-FFT: male, $9.8^{\circ}$, female, $10.7^{\circ}$; Lepto-FFT: male, $10.8^{\circ}$, female, $11.4^{\circ}$; p < 0.001). Conclusions: Our findings might serve as guidelines for setting the preferred CP according to FFT and sex.

• 치과방사선
• /
• 제29권1호
• /
• pp.33-42
• /
• 1999

Geometrically standardized dental radiographs were taken. We prepared Digital Cu-Equivalent Image Analyzing System for quantitative assessment of mandible bone. Images of radiographs were digitized by means of Quick scanner and personal Mcquintosh computer. NIH image as software was used for analyzing images. A stepwedge composed of 10 steps of 0.1mm copper foil in thickness was used for reference material. This study evaluated the effects of step numbers of copper wedge adopted for calculating equation. kVp and exposure time on the coefficient of determination(r²)of the equation for conversion to Cu-equivalent image and the coefficient of variation and Cu-Eq value(mm) measured at each copper step and alveolar bone of the mandible. The results were as follows: 1. The coefficients of determination(r²) of 10 conversion equations ranged from 0.9996 to 0.9973(mean=0.9988) under 70kVp and 0.16 sec. exposure. The equation showed the highest r was Y=4.75614612-0.06300524x +0.00032367x² -0.00000060x³. 2. The value of r² became lower when the equation was calculated from the copper stepwedge including 1.0mm step. In case of including 0mm step for calculation. the value of r showed variability. 3. The coefficient of variation showed 0.11, 0.20 respectively at each copper step of 0.2, 0.1mm in thickness. Those of the other steps to 0.9 mm ranged from 0.06 to 0.09 in mean value. 4. The mean Cu-Eq value of alveolar bone was 0.14±0.02mm under optimal exposure. The values were lower than the mean under the exposures over 0.20sec. in 60kVp and over 0.16sec. in 70kVp. 5. Under the exposure condition of 60kVp 0.16sec.. the coefficient of variation showed 0.03. 0.05 respectively at each copper-step of 0.3, 0.2mm in thickness. The value of r² showed over 0.9991 from both 9 and 10 steps of copper. The Cu-Eq value and the coefficient of variation was 0.14±0.01mm and 0.07 at alveolar bone respectively. In summary. A clinical application of this system seemed to be useful for assessment of quantitative assessment of alveolar provided high coefficient of determination is obtained by the modified adoption of copper step numbers and the low coefficient of variation for the range of Cu-Equivalent value of alveolar bone from optimal kVp and exposure time for each x-ray machine.

• 한국산학기술학회논문지
• /
• 제21권11호
• /
• pp.693-700
• /
• 2020

본 연구의 목적은 전통적인 인상채득방식으로 제작된 석고모형과 구강 디지털 인상법을 이용하여 제작된 폴리우레탄 모형의 각 계측지점을 비교함으로써 첨단 제조기술로 제작된 모형의 정확성을 검증하는 것이다. 유치악 아크릴릭 구강모형을 선정하여 기존에 사용하던 방식의 석고모형과 최신경향의 방식으로 모형을 각 10개씩 제작하였다. 계측지점은 총 6곳을 지정한 후, 2인의 검사자가 2회로 나누어 버니어 캘리퍼스를 이용하여 측정하였다. 제작방법에 따른 모형의 각 계측치의 평균, 표준편차, 계측치 차이의 평균 등의 기술 통계량으로 제시하였고, 정확성 검정을 위해 윌콕슨 부호순위 검정을 시행하였으며, 검사자 내, 검사자 간, 제작방법 간의 신뢰성 분석은 급내 상관계수 분석과 측정오차를 구하였다. 실험결과 신뢰성은 급내 상관계수의 범위는 0.76에서 0.99의 값이 나타나 높은 신뢰도를 보였으며, 모형 제작방법에 따른 정확성은 모든 계측지점 간의 거리를 비교하였을 때 폴리우레탄 모형이 작게 계측되었으며 0.09~0.20mm의 범위로 선행연구의 결과에 의해 임상적으로 오차범위를 허용할 수 있는 것으로 나타났다. 구강 디지털 인상법의 사용으로 제작된 모형은 임상적으로 적절한 것으로 판단되지만, 향후 보다 정밀하고 사용하기 편리한 치과용 모형을 제작하기 위한 연구들이 추가적으로 이루어져야 할 것이며, 다양한 임상 데이터를 활용한 평가가 이루어져야 할 것으로 사료된다.