• Journal of the Korea Convergence Society
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• v.11 no.2
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• pp.53-60
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• 2020

The purpose of this paper is to evaluate the image of the Styrofoam Wedge that can minimize the position change by supporting the wrist during the True PA and lateral examination of the wrist. In 50 people, the gap between the distal radius joint facet and the wrist bone was measured after the wrist True PA and lateral images were obtained using a general examination(vertical), tube angle(vertical:10°, lateral:20°) and Styrofoam Wedge(vertical). When joint spacing was measured in the True PA and lateral images of the wrist, general examination(5.54mm, 9.42mm), tube angle(2.05mm, 5.07mm) and Styrofoam Wedge(1.79mm, 5.46mm) were shown to be small. The smaller the joint spacing, the easier it is to observe that is open. Therefore, True PA and lateral imaging of the wrist Styrofoam Wedge can reduce the distortion of the image and thus acquire images of high diagnostic value. In addition, it may be possible to reduce the deviation caused by the change of patient's position during re-projection.

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.1
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• pp.63-94
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• 1990

The purpose of this study was to analyze the displacement and the magnitude and the mode of distribution of the stresses in the lower overdenture, the mucous membrane, the abutment tooth and the mandibular supporting bone when various denture base materials, such as acrylic resin and 0.5mm metal base, and various denture base designs were subjected to different loading schemes. For this study, the two-dimensional finite element method was used. Mandibular arch models, with only canine remaining, were fabricated. In the first denture base design, a space, approximately 1mm thick, was prepared between the denture and the dome abutment. In the second denture base design, contact between the denture and the dome abutment was eliminated except the contact of the occlusal third of the abutment. In order to represent the same physiological condition as the fixed areas of the mandible under loading schemes, the eight nodes which lie at the mandibular angle region, the coronoid process and the mandibular condyle were assumed to be fixed. Each model was loaded with a magnitude of 10 kgs on the first molar region(P1) and 7 kgs on the central incisal region (P2) in a vertical direction. Then the force of 10 kgs was applied distributively from the first premolar to the second molar of each model in a vertical direction(P3). The results were as follows. : 1. When the testing vertical loads were given to the selected points of the overdenture, the overdenture showed the rotatory phenomenon, as well as sinking and the displacements of alveolar ridge, abutment and lower border of mandible under the metal base overdenture were less than those under the acrylic resin overdenture. 2. The maximum principal stresses(the maximum tensile stresses) being considered, high tensile stresses occured at the buccal shelf area, the posterior region of the ridge crest and the anterior border region of the mandibular ramus. 3. The minimum principal stresses(the maximum compressive stresses) being considered, high compressive stresses occured at the inferior and posterior border region of the mandible, the mandibular angle and the posterior border region of the mandibular ramus. 4. The vertical load on the central incisal region(P2) produced higher equivalent stress in the mandible than that on any other region(P1, P3) because of the long lever arm distance from the fixed points to the loading point. 5. Higher equivalent stresses were distributed throughout the metal base overdenture than the resin base overdenture under the same loading condition. 6. The case of occlusal third contact of the abutment to the denture produced higher equivalent stresses in the abutment, the mandibular area around the abutment and the overdenture than the case of a 1mm space between the denture and the abutment. 7. Without regard to overdenture base materials and designs, the amounts and distribution patterns of equivalent stresses under the same loading condition were similar in the mucous membrane.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.1
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• pp.233-248
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• 1991

The purpose of this study was to qunatatively analyze the stress patterns induced in the abutment, superstructure, supporting bone and to determine the deflection of abutment and superstructure by appling occlusal force to natural teeth supported fixed prostheses and implant-supported fixed prostheses. The analysis has been conducted by using the two dimensional finite element method. The implant and natural tooth-supported bridge has a first molar pontic supported by mandibular second bicuspid and implant posterior retainer, which were rigidly(Model A) or flexible(Model B). The natural teeth-supported bridge has a first molar pontic supported by mandibular second bicuspid and second molar, which were rigidly splinted together(Model C). 63.5kg(Load P1) of localized load on central fossa of first molar pontic and 24kg(Load P2) of distributed load on each occlusal surface were applied respectively. 1. The coronal portion of premolar pontic and posterior abutment in fixed partial denture deflected inferiorly in order of Model B, Model C and Model A under Load P1 and Load P2. 2. Mesial displacement of the coronal portion of premolar showed in Model A, Model B and Model C under Load P1, but mesial displacement of that in Model B and distal displacement of that in Model A and Model C showed under Load P2. 3. Mesial displacement of the coronal portion of the pontic and distal displacement of the coronal portion of posterior abutment showed in Model A, Model B and Model C under Load P1 and Load P2. Displacement in the case of Model B was greater than that of Model A and Model C. 4. In the case Model A under Load P1 and Load P2, high stress apically was concentrated in the mesiocervical portion of the posterior abutment than in the disto-cervical portion of the premolar. 5. In the case of Model B under Load P1 and Load P2 high stress was concentrated in the case of the premolar than in that of posterior abutment and high stress especially was concentrated in the connected portion of pontic and posterior abutment. 6. In the case of Model C under Load P1 and Load P2, high stress was concentrated in the distal area of the cornal portion of premolar and the mesial area of the coronal portion of posterior abutment, and stress pattern was anteroposterially symmetric around the pontic. 7. Load P1 and Load P2 compared, stress magnitude was different but stress pattern was similar in Model A, Model B and Model C. 8. Under Load P1 and P2, stress magnitude in the mesial distal portion and the portion of root apex of the posterior abutment was in order of Model B, Model A and Model C.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.6
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• pp.717-723
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• 2007

Statement of problem. Unreasonable distal cantilevered implant-supported prosthesis can mask functional problems of reconstruction temporarily, but it can cause serious strain and stress around its supported implant and surrounding alveolar bone. Purpose. The purpose of this study was to evaluate strain of implants supporting distal cantilevered fixed prosthesis with two different cantilevered length under distal cantilevered static load. Material and methods. A partially edentulous mandibular test model was fabricated with auto-polymerizing resin (POLYUROCK; Metalor technologies, Stuttgart, Swiss) and artificial denture teeth (Endura; Shofu inc., Kyoto, Japan). Two implants-supported 5-unit screw-retained cantilevered fixed prosthesis was made using standard methods with Type III gold alloy (Harmony C&B55; Ivoclar-vivadent, Liechtenstein, Germany) for superstructure and reinforced hard resin (Tescera; Ivoclar-vivadent, Liechtenstein, Germany) for occlusal material. Two strain gauges (KFG-1-120-C1-11L1M2R; KYOWA electronic instruments, Tokyo, Japan) were then attached to the mesial and the distal surface of each standard abutment with adhesive (M-bond 200; Tokuyama, Tokyo, Japan). Total four strain gauges were attached to test model and connected to dynamic signal conditioning strain amplifier (CTA1000; Curiotech inc., Paju, Korea). The stepped $20{\sim}100$ N in 25 N increments, cantilevered static load 8mm apart (Group I) or 16mm apart (Group II), were applied using digital push-pull gauge (Push-Pull Scale & Digital Force Gauge, Axis inc., Seoul, Korea). Each step was performed ten times and every strain signal was monitored and recorded. Results. In case of Group I, the strain values were surveyed by $80.7{\sim}353.8{\mu}m$ in Ch1, $7.5{\sim}47.9{\mu}m/m$ in Ch2, $45.7{\sim}278.6{\mu}m/m$ in Ch3 and $-212.2{\sim}718.7{\mu}m/m$ in Ch4 depending on increasing cantilevered static load. On the other hand, the strain values of Group II were surveyed by $149.9{\sim}612.8{\mu}m/m$ in Ch1, $26.0{\sim}168.5{\mu}m/m$ in Ch2, $114.3{\sim}632.3{\mu}m/m$ in Ch3, and $-323.2{\sim}-894.7{\mu}m/m$ in Ch4. Conclusion. A comparative statistical analysis using paired sample t-test about Group I Vs Group II under distal cantilevered load shows that there are statistical significant differences for all 4 channels (P<0.05).

• Journal of the Korean Academy of Esthetic Dentistry
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• v.25 no.1
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• pp.35-49
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• 2016

With the increasing demand for aesthetic implant dentistry, the importance of implant restoration is emphasized not only in the functional aspect but also in the aesthetic aspect. The aesthetic restoration of dental implants in the anterior maxilla is a challenge for clinicians because it requires proper harmony in three following conditions; reconstruction of hard tissue, soft tissue, and aesthetic prosthesis. The soft tissue aesthetics are dependent upon the condition of the supporting hard tissue because the osseous structure provides a framework for the development of a healthy and aesthetic soft tissue interface. Therefore, the augmentation of hard tissue is a first step and especially, optimal 3-dimensional position of implant is the most important factor in aesthetic implant restoration. The management of soft tissue is a second step, and the final step is a restoration of harmonic prosthesis using provisional restoration with proper emergence profile. This clinical report describes the procedure of bone augmentation in labial dehiscence defect, Vascularized Interpositional Periosteal-Connective Tissue (VIP-CT) flap for aesthetic anterior soft tissue, and the importance of provisional restoration and impression taking stage with customized impression coping.

• Journal of Periodontal and Implant Science
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• v.31 no.2
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• pp.277-285
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• 2001

Periodontal disease is characterized by inflammation and subsequent loss and/or damage to tooth-supporting tissues such as bone, cementum,and periodontal ligament. Periodontal ligament and cementum are the key tissues in the initial process of regeneration following periodontal disease. Therefore, studies on cementoblasts, which form cementum are emphasized. It is still unclear which cells cementoblast differentiate from. This study was conducted under the hypothesis that PDL fibroblast can differentiate into either cementoblast or osteoblast depending on the conditions of surrounding tissue. Clinically, with excessive traction force of orthodontic appliances or excessive occlusion hypercementosis is observed, and this has been confirmed histologically. Consequently, activation of cementoblast can be expected in rats when mechanical stimuli are given to PDL fibroblast. Therefore, the purpose of this article is to prove that PDL fibroblast differentiates into cementoblast in rats under mechanical stimuli using histologic and molecular methods. In this study, twenty rats were given hard diet. Ten of them were sacrificed after 1 week, and the others were sacrificed after two weeks. Slides were made from tooth specimen, and they were studied under the microscope. In addition, PDL fibroblast and cementum from the extracted teeth were analyzed with Northern blotting. In histologic examination, as time passed, PDL fibroblast migrated to the dentin side, differentiated into cementoblast, and formed new cementum. In Northern blotting, it was found that mRNA expression of cementoblast-specific proteins such as BSP, OC, OPN, and type I collagen were more prominent in rats sacrificed after 2 weeks of hard-diet than rats sacrificed after 1 week. From these findings we can conclude that PDL fibroblast can differentiate into cementoblast under mechanical stimuli. We think that 'Rat Models' used in this study will be beneficial to future studies regarding cementoblast.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.432-461
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• 1995

The basic principles in the design of Class II amalgam cavity preparations have been modified but not changed in essence over the last 90 years. The early essential principle was "extension for prevention". Most of the modifications have served to reduce the extent of preparation and, thus, increase the conservation of sound tooth structure. A more recent concept relating to conservative Class II cavity preparations involves elimination of occlusal preparation if no carious lesion exists in this area. To evaluate the ideal ClassII cavity preparation design, if carious lesion exists only in the interproximal area, three cavity design conditions were studied: Rodda's conventional cavity, simple proximal box cavity and proximal box cavity with retention grooves. In this study, MO amalgam cavity was prepared on maxillary first premolar. Three dimensional finite element models were made by serial photographic method. Linear, eight and six-nodal, isoparametric brick elements were used for the three dimensional finite element model. The periodontal ligament and alveolar bone surrounding the tooth were excluded in these models. Three types model(B option, Gap option and R option model) were developed. B option model was assumed perfect bonding between the restoration and cavty wall. Gap option model(Gap distance: $2{\mu}m$) was assumed the possibility of play at the interface simulated the lack of real bonding between the amalgam and cavity wall (enamel and dentin). R option model was assumed non-connection between the restoration and cavty wall. A load of 500N was applied vertically at the first node from the lingual slope of the buccal cusp tip. This study analysed the displacement, 1 and 2 direction normal stress and strain with FEM software ABAQUS Version 5.2 and hardware IRIS 4D/310 VGX Work-station. The results were as followed. 1. Rodda's cavity form model showed greater amount of displacement with other two models. 2. The stress and strain were increased on the distal marginal ridge and buccopulpal line angle in Rodda's cavity form model. 3. The stress and strain were increased on the central groove and a part of distal marginal ridge in simple proximal box model and proximal box model with retention grooves. 4. With Gap option, Rodda's cavity form model showed the greatest amount of the stress on distal marginal ridge followed by proximal box model with retention grooves and simple proximal box model in descending order. 5. With Gap option, simple proximal box model showed greater amount of stress on the central groove with proximal box model with retention grooves. 6. Retention grooves in the proximal box played the role of supporting the restorations opposing to loads.

• Journal of Dairy Science and Biotechnology
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• v.42 no.2
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• pp.48-63
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• 2024

This study investigated the 𝛽-glucosidase activity of lactic acid bacteria and specifically eleutheroside E and B from Acanthopanax senticosus after bioconverting them into syringaresinol (SYR). Out of 125 lactic acid bacteria strains isolated from kimchi and other sources, 46 exhibiting both extracellular and internal 𝛽-glucosidase activity were identified. Notably, strains LFFR 20-011 (Lactobacillus curvatus) and LFFR 20-043/LFR20-050 (Levilactobacillus brevis) enhanced SYR production by more than two-fold during Acanthopanax senticosus fermentation. Further investigation revealed that SYR significantly promoted osteoblast differentiation, as evidenced by the increased mRNA expression levels of early and mature osteoblast markers, including Runx2, type I collagen, and osteocalcin. These findings suggested that the enhanced presence of SYR through bioconversion by Acanthopanax senticosus may improve bone health. These results provide foundational data supporting the development of lactic-acid-bacteria-fermented Acanthopanax senticosus as a functional food aimed at promoting skeletal health in older adults.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.239-245
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• 2016

Purpose: The purpose of this study was to identify clinical complications in removable partial denture (RPD) with implant-supported surveyed prostheses, and to analyze the factors associated with the complications such as location of the implant, splinting adjacent prostheses, the type of retentive clasps, Kennedy classification, and opposing dentition. Materials and Methods: A retrospective clinical study was carried out for 11 patients (7 male, 4 female), mean age of 67.5, who received RPD with Implant-supported surveyed prostheses between 2000 and 2016. The mechanical complications of 11 RPDs and 37 supporting implant prostheses and the state of natural teeth and peripheral soft tissue were examined. Then the factors associated with the complications were analyzed. Results: The average of 3.4 implant-supported prostheses were used for each RPD. Complications found during the follow-up period of an average of 42.1 months were in order of dislodgement of temporary cement-retained prostheses, opposing tooth fracture/mobility, screw fracture/loosening, clasp loosening, veneer porcelain fracture, marginal bone resorption and mobility of implant, artificial tooth fracture. Complications occurred more frequently in anterior region compared to posterior region, non-splinted prostheses compared to splinted prostheses, surveyed prostheses applied by wrought wire clasp compared to other clasps, and natural dentition compared to other removable prostheses as opposing dentition. There were no significant differences in complications according to the Kennedy classification. Conclusion: All implant-assisted RPD functioned successfully throughout the follow-up. However, further clinical studies are necessary because the clinical evidences are still not enough to guarantee the satisfactory prognosis of implant-assisted RPD for long-term result.

• The Journal of Korean Academy of Prosthodontics
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• v.31 no.2
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• pp.271-300
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• 1993

The purpose of this study was to analyze the stress distribution at supporting bone according to the types of connection modality between implant and tooth in the superstrcture. This investigation evaluated the stress patterns in a photoelastic model produced by three different types of dental implants such as Branemark, Steri-Oss, IMZ and resin tooth using the techniques of quasi three dimensional photoelasticity. The teeth-supported bridge had a first molar pontic supported by second premolar and second molar as a control group. The implant and toothsupported bridge had a first molar pontic supported by second premolar and implant posterior retainer as an experimental group. Prostheses were mechanically connected to an adjacent second premolar by the rigid of nonrigid connection, Nonrigid connection used an attachment placed between the tooth-supported and fixture-supported component. The female(keyway) of attachment was placed on the distal end of the retainer supported by the tooth ; the male(Key) of attachment connected to the osseointegrated bridge was engaged into the keyway. All prostheses were casted in the same nonprecious alloy and were cemented and screwed on their respective abutments and implants. 16㎏ of vertical loads on central fossae of second premolar, first molar pontic, implant of second molar were applied respectively and 6.5㎏ of inclined load on middle buccal surface of first molar pontic was applied. The results were as follows : 1. Under the vertical load on the central fossa of first mloar pontic, the stress developed at the apex of tooth of implat was more uniformly distributed in the case of nonrigid connection than in the case of rigid connection. 2. Under the vertical load on the central fossa of first molar pontic, the stress developed around the cervical area of tooth of implant was larger in the case of rigid connection than in the case of nonrigid connection because the bending moment was more occured in the case of rigid connection than in the case of nonrigid connection. 3. Stress was more restricted to the loaded side of nonrigid connection than to that of rigid connection 4. Under the inclined load. The set screw loosening of implant was more easily occured in the case of nonrigid connection than in the case of rigid connection due to torque moment. 5. In the case of Branemark implant, the stress concentration in second premolar was larger and the stress developed around the cervical area of implant was lower than any other cases under the vertical load, because Branemark implant with the flexible gold screw was showed in incline toward second premolar by a bending moment. 6. The stress developed around the apex of tooth or implant was more uniformly distributed in the case of Steri-Oss implant with stiff screw than in the case of Branemark implant under the vertical load. But, the stress developed around the cervical area of the Steri-Oss implant was larger than that of any other implants because bending moment was occured by vertical migration of second premolar. 7. The stress distribution in the case of IMZ implant was similar to the case of natural teeth under small vertical load. But, the residual stress around the implant was showed to occurdue to deformation of IMC and sinking of screw under larger vertical load.