• Imaging Science in Dentistry
• /
• v.51 no.4
• /
• 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
• /
• v.13 no.6
• /
• 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 Korean Academy of Prosthodontics
• /
• v.59 no.1
• /
• pp.27-35
• /
• 2021

Purpose: The purpose of this study is to compare the accuracy of digital scans of implants according to different shapes of scanbodies, and to compare the accuracy of library merging according to different oral exposure height. Materials and methods: A master model with a single tooth edentulous site was prepared. For the first experiment, three types of intraoral scanbodies were prepared, divided into three groups, and the following experiments were conducted for each group: An internal hex implant was placed. The master model with the scanbody connected was scanned with a model scanner, and a master reference file (control group) was created. 10 files (experimental group) were created by performing 10 consecutive scans with an intraoral scanner. After superimposing the control and experimental groups, the following values were calculated: 1) Distance deviation of a designated point on the scanbody 2) Angle deviation of the major axis of the scanbody. For the second experiment, the scanbody scan data were prepared in 6 different heights. Library files were merged with each of the scan data. The distance and angular deviation were calculated using the 7 mm scan data as control group. Results: In the first experiment, there were no significant differences between A and B (P=.278), B and C (P=.568), and C and A (P=.711) in the distance deviations. There were no significant differences between A and B (P=.568), B and C (P=.546), and C and A (P=.112) in the angular deviations. Also, the scanbody showed significantly higher library merging accuracy in the groups with high oral exposure height (P<.5). Conclusion: There were no significant differences in scan accuracy according to the different shapes of scanbodies, and the accuracy of library merging increased according to exposure height of the scanbody in the oral cavity.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.23 no.4
• /
• 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.

• Journal of Korean society of Dental Hygiene
• /
• v.13 no.6
• /
• 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
• /
• v.45 no.1
• /
• 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.

• The korean journal of orthodontics
• /
• v.47 no.2
• /
• 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.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.29 no.1
• /
• 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.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.11
• /
• pp.693-700
• /
• 2020

This study compared the accuracy and reliability of definitive casts fabricated from a digital impression and conventional impression technique. A master model with the prepared upper full-arch tooth was used. Samples of ten plaster models and ten polyurethane models were duplicated using a selected standard master model. Six linear measurements were recorded between the landmarks, directly on each of the stone models and the polyurethane models on two occasions by a double examiner. The Wilcoxon signed-rank test, interclass correlation coefficient (ICC), measurement error (MSE), and limit of agreement (LoA) were used for statistical analysis. The ICC ranged from 0.76 to 0.99 when comparing the stone models and polyurethane models. The mean difference between the stone models and polyurethane models ranged from 0.09mm to 0.20mm, suggesting that stone models might be slightly larger than polyurethane models. Based on this study, the accuracy of the polyurethane models in evaluating the performance of an oral scanner and subtractive technology was acceptable. Further studies will be needed on patient subjects under clinical conditions that may involve missing or malpositioned teeth and fixed dental prostheses because this study was limited to use a standard master model and duplicated sample models in a laboratory setting.

• Restorative Dentistry and Endodontics
• /
• v.30 no.5
• /
• pp.393-401
• /
• 2005

The purpose of this study was to compare the canal configuration after shaping by ProTaper rotary files and ProTaper hand files in resin simulated canals. Forty resin simulated canals with a curvature of J-shape and S-shape were divided into four groups by 10 blocks each Simulated root canals in resin block were prepared by ProTaper rotary files and ProTaper hand files using a crown-down pressureless technique All simulated canals were prepared up to size $\#25$ file at end-point of preparation. Pre- and post-instrumentation images were recorded with color scanner. Assessment of canal shape was completed with an image analysis program. Measurements were made at 0, 1, 2, 3, 4, 5, 6 and 7 mm from the apex. At each level, outer canal width, inner canal width, total canal width, and amount of transportation from original axis were recorded. Instrumentation time was recorded. The data were analyzed statistically using independent t-test. The result was that ProTaper hand files cause significantly less canal transportation from original axis of canal body and maintain original canal configuration better than ProTaper rotary files, however ProTaper hand files take more shaping time.