• Journal of dental hygiene science
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• v.23 no.4
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• pp.245-254
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• 2023

Background: This study aimed to determine the skeletal and dental effects in pediatric and adolescent Korean patients with Class II Division 1 malocclusion treated using the Invisalign Mandibular Advancement (MA^®) appliance. Methods: The study included patients aged 6 to 18 years who received orthodontic treatment with the MA^® appliance for Class II Division 1 malocclusion at the Department of Pediatric Dentistry, Wonkwnag University Daejeon Dental Hospital, between July 1, 2018, and December 31, 2021. The treatment group consisted of 20 patients, 10 boys and 10 girls. The control participants were also 10 boys and 10 girls. Lateral cephalometric radiographs were taken before and after treatment, and 41 measurements of skeletal and dental changes were measured and analyzed using the V-Ceph^TM 8.0 (Osstem Implant). All analyses were performed using SPSS software (IBM SPSS for Windows, ver 26.0; IBM Corp.), and statistical significance was tested using paired and independent samples t-tests for within-group and between-group comparisons, respectively. Results: The patients in the treatment group showed significant decreases in ANB (A point, Nasion, B point), maxillary protrusion, maxillary anterior incisor labial inclination, and maxillary protrusion after treatment. However, when compared with the growth changes observed in the control group, only ANB and maxillary protrusion decreased, with no significant differences in SNA, SNB, and mandibular length. Conclusion: Collectively, the results of this study confirm that the use of MA^® appliance in pediatric and adolescent Korean patients with Class II Division 1 malocclusion results in a reduction of anteroposterior skeletal and dental disharmony.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.4
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• pp.301-307
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• 2002

Direct bonded SOI wafer pairs with $Si ll SiO_2/Si_3N_4 ll Si$ the heterogeneous insulating layers of SiO$_2$-Si$_3$N$_4$are able to apply to the micropumps and MEMS applications. Direct bonding should be executed at low temperature to avoid the warpage of the wafer pairs and inter-diffusion of materials at the interface. 10 cm diameter 2000 ${\AA}-SiO_2/Si(100}$ and 560 $\AA$- ${\AA}-Si_3N_4/Si(100}$ wafers were prepared, and wet cleaned to activate the surface as hydrophilic and hydrophobic states, respectively. Cleaned wafers were pre- mated with facing the mirror planes by a specially designed aligner in class-100 clean room immediately. We employed a heat treatment equipment so called fast linear annealing(FLA) with a halogen lamp to enhance the bonding of pre mated wafers We kept the scan velocity of 0.08 mm/sec, which implied bonding process time of 125 sec/wafer pairs, by varying the heat input at the range of 320~550 W. We measured the bonding area by using the infrared camera and the bonding strength by the razor blade clack opening method, respective1y. It was confirmed that the bonding area was between 80% and to 95% as FLA heat input increased. The bonding strength became the equal of $1000^{\circ}C$ heat treated $Si ll SiO_2/Si_3N_4 ll Si$ pair by an electric furnace. Bonding strength increased to 2500 mJ/$\textrm{m}^2$as heat input increased, which is identical value of annealing at $1000^{\circ}C$-2 hr with an electric furnace. Our results implies that we obtained the enough bonding strength using the FLA, in less process time of 125 seconds and at lowed annealing temperature of $400^{\circ}C$, comparing with the conventional electric furnace annealing.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.27 no.2
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• pp.82-96
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• 2018

3D printing is a process of producing 3d object from a digital file in STL format by joining, bonding, sintering or polymerizing small volume elements by layer. The various type of 3d printing is classified according to the additive manufacturing strategies. Among the types of 3D printer, SLA(StereoLithography Apparatus) and DLP(Digital Light Processing) 3D printer which use polymerization by light source are widely used in dental office. In the previous study, a full-arch scale 3d printed model is less precise than a conventional stone model. However, in scale of quadrant arch, a 3d printed model is significantly precise than a five-axis milled model. Using $3^{rd}$ Party dental CAD program, full denture, provisional crowns and diagnostic wax-up model are fabricated by 3d printer in dental office. In Orthodontics, based on virtual setup model, indirect bracket bonding tray can be generated by 3d printer. And thermoforming clear aligner can be fabricated on the 3d printed model. 3D printed individual drilling guide enable the clinician to place the dental implant on the proper position. The development of layer additive technology enhance the quality of 3d printing object and shorten the operating time of 3D printing. In the near future, traditional dental laboratory process such as casting, denture curing will be replaced by digital 3D printing.