• The korean journal of orthodontics
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• v.50 no.4
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• pp.229-237
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• 2020

Objective: To evaluate the construction reproducibility of a composite tooth model (CTM) composed of an intraoral-scanned crown and a cone-beam computed tomography (CBCT)-scanned root. Methods: The study assessed 240 teeth (30 central incisors, 30 canines, 30 second premolars, and 30 first molars in the maxillary and mandibular arches) from 15 young adult patients whose pre-treatment intraoral scan and CBCT were available. Examiner-Reference (3 years' experience in CTM construction) and Examiners-A and Examiner-B (no experience) constructed the individual CTMs independently by performing the following steps: image acquisition and processing into a three-dimensional model, integration of intraoral-scanned crowns and CBCT-scanned teeth, and replacement of the CBCT-scanned crown with the intraoral-scanned crown. The tooth axis angle in terms of mesiodistal angulation and buccolingual inclination of the CTMs constructed by the three examiners were measured. To assess the construction reproducibility of CTMs, intraclass correlation coefficient (ICC) assessments were performed. Results: The ICC values of mesiodistal angulation and buccolingual inclination among the 3 examiners showed excellent agreement (0.950-0.992 and 0.965-0.993; 0.976-0.994 and 0.973-0.995 in the maxillary and mandibular arches, respectively). Conclusions: The CTM showed excellent construction reproducibility in mesiodistal angulation and buccolingual inclination regardless of the construction skill and experience levels of the examiners.

• The korean journal of orthodontics
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• v.52 no.1
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• pp.42-52
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• 2022

Objective: This study compared soft tissue changes after extraction of the four premolars followed by maximum retraction of the anterior teeth according to the type of anterior teeth movement: tipping and translation. Methods: Patients who had undergone orthodontic treatment involving the extraction of four premolars were retrospectively selected and divided into either the tipping (n = 27) or translation (n = 26) groups based on the retraction of the incisor root apex and the axis changes of the incisors during the treatment period. Lateral pre- and post-treatment cephalograms were analyzed. Results: There were no significant differences between the tipping and translation groups before treatment. The retraction amounts of the root apex of the upper and lower incisors in the tipping group were 0.33 and 0.26 mm, respectively, and 5.02 and 5.31 mm, respectively, in the translation group (p < 0.001). The posterior movements of soft tissue points A and B in the tipping group were 0.61 and 1.25 mm, respectively, and 1.10 and 3.25 mm, respectively, in the translation group (p < 0.01). The mentolabial sulcus angle increased by 5.89° in the tipping group, whereas it decreased by 8.13° in the translation group (p < 0.001). Conclusions: An increased amount of retraction of the incisor root apex led to the increased posterior movement of soft tissue points A and B, and this appeared more distinct in cases involving the lower incisor and lower lip.

• Journal of Periodontal and Implant Science
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• v.26 no.2
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• pp.334-349
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• 1996

Regeneration of the periodontal tissue destroyed by periodontal disease is one of the final goals of periodontal therapy. In the past few years, periodontists have used various alloplastic grafting materials in an attempt to regenerate bone lost from periodontal disease. These materials have used widely because they have shown to be nontoxic, biologically compatible with surrounding host tissue and chemically similar to bone. The purpose of this study was to investigate the effect of Porous Resorbable Calcium Carbonate and Porous Replamineform Hydroxyapatite on the regeneration of the alveolar bone and the healing of roots transplanted into the periodontally diseased extraction sockets of dogs. The experimental chronic periodontitis was induced by elastic ligatures on the 2nd and 3rd mandibular premolars of 2 adult dogs for 8weeks after surgically creating periodontal defect. The extracted root were split in half along the long-axis, and the extend of plaque exposure was marked on the root surfaces with burs. The roots were inserted in extraction sockets with Porous Resorbable Calcium Carbonate(PRCC) in left side and with Porous Replaminefrom Hydroxyapatite(PRH) in right side. The flaps were sutured to cover the sockets completely. The animals were sacrificed after 12 weeks of healing, and the specimens were examined histologically. The results were as follows: 1. No inflammatory reactions were observed in either groups. 2. Hoot resorption was observed in both groups while the general outline of the roots were maintained. 3. PRCC was almost completely resorbed and replaced with new bone, while R.H.A. was not resorbed & remained encased in newly-formed C-T and alveolar bone. 4. PRH was encapsulated with alveolar bone which has been deposited from apical & lateral area of the sockets, while the coronal portion of the sockets were filled with C-T. 5. In both groups, the resorbed portions of the roots were replaced with new bone. These results suggest that either PRCC or PRH may not interfere with bone formation or healing in extraction sockets, and in some degree, retard the root resorption. Because the roots maintained in anatomy, we think that graft materials prevent the root resorption.

• Restorative Dentistry and Endodontics
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• v.35 no.6
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• pp.479-485
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• 2010

Objectives: The aim of this study was to compare the push-out bond strengths of resin cement/fiber post systems to post space dentin using different application methods of resin cement. Materials and Methods: Thirty extracted human premolars were selected and randomly divided into 3 groups according to the technique used to place the cement into root canal: using lentulo-spiral instrument (group Lentulo), applying the cement onto the post surface (group Direct), and injecting the material using a specific elongation tip (group Elongation tip). After shaping and filling of the root canal, post space was drilled using Rely-X post drill. Rely-X fiber post was seated using Rely-X Unicem and resin cement was light polymerized. The root specimens were embedded in an acrylic resin and the specimens were sectioned perpendicularly to the long axis using a low-speed saw. Three slices per each root containing cross-sections of coronal, middle and apical part of the bonded fiber posts were obtained by sectioning. The push-out bond strength was measured using Universal Testing Machine. Specimens after bond failure were examined using operating microscope to evaluate the failure modes. Results: Push-out bond strengths were statistically influenced by the root regions. Group using the elongation tip showed significantly higher bond strength than other ways. Most failures occurred at the cement/dentin interface or in a mixed mode. Conclusions: The use of an elongation tip seems to reduce the number of imperfections within the selfadhesive cement interface compared to the techniques such as direct applying with the post and lentulospiral technique.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.1
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• pp.162-174
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• 1992

Blades are one of the critical parts of the wind machine. This paper presents a design procedure for the blade of a 7m diameter horizontal axis wind turbine with the constraint conditions of stresses and fundamental frequency. This blade consists of glass/polyester woven fabric and unidirectional prepreg. It was firstly designed by the classical beam theory on the assumption that torque box sustains all external loads and the reliability of the blade was then inspected in the preliminary estimation by using FEM.

• Journal of Chest Surgery
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• v.21 no.6
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• pp.984-989
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• 1988

2-D echocardiographic examination of the aortic root diameter was known to be useful in the selection of the size of the prosthetic valve. Valve-patient mismatch was occasionally a serious problem after valve replacement, especially in aortic valve disease. Preoperative knowledge of the patient`s valve annulus size is therefore of great importance in the surgical management of these patients. So the relationship between preoperative 2-D echocardiographic diameter of the annulus size and replaced prosthetic valve were evaluated. 13 patients were analyzed in this study. 2-D echocardiographic measurements of aortic annulus diameter, as determined from the parasternal long axis view and apical four chamber view, demonstrated a high correlation with actual prosthetic valve size implanted at surgery[r=0.86, p< 0.001, SEE=1.08].

• Journal of Acupuncture Research
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• v.15 no.2
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• pp.29-41
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• 1998

The effect of Cervi Cornu Parvum aqua-acupuncture on serum levels of sex hormone was investigated in ovariectomized rats. Water extract of Cervi Cornu Parvum was daily injected for 30 days at points in rats corresponding to bilateral Taixi (Ki. 3) points of human and non-point at root of tail after ovariectomy, respectively. Serum levels of estradiol, testosterone, progesterone, LH and FSH were measured at 2 and 4 weeks after aqua-acupuncture treatment, respectively. Compared with ovariectomized rats, significant increase of estradiol and progesterone and significant decrease of FSH and LH were elicited at 2 and 4 weeks after aqua-acupuncture treatment. Aqua-acupuncture treatment at non-point did not produce any remarkable effect. These findings suggest aqua-acupuncture may restore dysfunction of hypothalamic-pituitary-ovarian axis, associated with a significant increase of serum estradiol level in ovariectomized rats.

• The korean journal of orthodontics
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• v.23 no.1 s.40
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• pp.137-145
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• 1993

Inverted maxillary incisor is that maxillary incisor rotates to the counterclockwise direction. The incisal margin and root apex of the impacted incisor is palpated at the mucobuccal fold near the labial frenum and on the palate among the rugae, respectively. Orthodontists confront ectopically erupting teeth in various locations. In the past, extraction of impacted teeth that deviated from their normal course of eruption had been performed indiscriminately. But, if it has not any clearcut contraindications, effeort should be made to achieve optimal esthetic results by conservative means, combining the skills of oral surgeon and orthodontist. The present report provides an illustration of satisfactory correction of a inverted maxillary incisor with surgical intervention and many springs that correct the tooth axis. This technique provides the clinician with an additional means to avoid unnecessary extraction of inverted teeth in certain cases.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.80-90
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• 2006

The influence of waves on the dynamic properties of bending moments at the root of blades of tidal stream vertical axis rotors is reported. Blade theory for wind turbine is combined with linear wave theory and used to analyse this influence. Experiments were carried out to validate the simulation and the comparison shows the usefulness of the theory in predicting the bending moments. The mathematical model is then used to study the importance of waves for the fatigue design of the blade-hub connection.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.6
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• pp.886-895
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• 2009

The purpose of this work is to compare and analyze computed results with experimental data of NREL (National Renewable Energy Laboratory) Phase VI for the whole operating conditions of various wind speeds using $\kappa-\omega$ turbulence model provided in the commercial code, FLUENT. Performance results such as power coefficient, shaft torque, pressure coefficient show a good agreement with experimental data. But, root bending moment is over-predicted than the experimentally measured value by about 30% for the whole operating conditions because of indefinite measurement reference. Nevertheless, these results qualitatively show a good tendency in the aspect of aerodynamic performance. As wind speed increases, streamlines on the surface of blade show more and more complex pattern.