• Maxillofacial Plastic and Reconstructive Surgery
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• 제31권2호
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• pp.116-126
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• 2009

The use of short implants has been accepted risky from biomechanical point of view. However, short implants appear to be a long term viable solution according to recent clinical reports. The purpose of this study was to investigate the effect of different diameter and length of implant size to the different type of bone on the load distribution pattern. Stress analysis was performed using 3-dimensional finite element analysis(3D-FEA). A three-dimensional linear elastic model was generated. All implants modeled were of the various diameter(${\phi}4.0$, 4.5, 5.0 and 6.0 mm) and varied in length, at 7.0, 8.5 and 10.0 mm. Each implant was modeled with a titanium abutment screw and abutment. The implants were seated in a supporting D2 and D4 bone structure consisting of cortical and cancellous bone. An amount of 100 N occlusal load of vertical and $30^{\circ}$ angle to axis of implant and to buccolingual plane were applied. As a result, the maximum equivalent stress of D2 and D4 bones has been concentrated upper region of cortical bone. As the width of implant is increased, the equivalent stress is decreased in cancellous bone and stress was more homogeneously distributed along the implants in all types of bone. The short implant of diameter 5.0mm, 6.0mm showed effective stress distribution in D2 and D4 bone. The oblique force of 100N generated more concentrated stress on the D2 cortical bone. Within the limitations of this study, the use of short implant may offer a predictable treatment method in the vertically restricted sites.

• 대한치과보철학회지
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• 제29권3호
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• pp.1-32
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• 1991

Tho osseointegrated dental prosthetic treatment has develped for the edentulous patient with severely resorbed alveolar ridge, and has given us a successful clinical results to date. Nowadays the partially edentulism is included among the indications of the osseointegrated prosthetic treatment. 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 superstructure. Two dimensional finite element stress analysis was applied for this study. FEM models were created using software Super SAP for MBM 16bit personal computer. Three modalities of connection were modeled and analyzed under load condition. The results were as follws: 1. The stress develped at tooth and implant in the cancellous bone was lower in the case of rigid connection than in the case of norigid connection, but higher between the two implants in the case of rigid connection than in the case of nonrigid connection. 2. The stress developed at the cortical bone and at the supporting bone interface was lower in the case of rigid connection than in the case of nonrigid connection 3. The stress developed at the supporting tissue interface of the implant nearby the tooth, was lower in the case of rigid connection than in the case of nonrigid connection. 4. The stress developed at the supporting tissue interface of posteriormost implant, was same between the cases of rigid and nonrigid connection. 5. The stress distribution related to the freestanding case was generally similar to the stress distribution pattern of nonrigid connection case. 6. The magnitude of applied load which produces deformation within elastic limit, had influence on the absolute value of stress, but had no influence on the pattern of stress distribution of the same case.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제33권5호
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• pp.485-493
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• 2007

Purpose: Heart rate variability(HRV) is the clinical consequence of various influences of the autonomic nervous system(ANS) on heart beat. HRV can estimate the potential physiologic rhythm from the interval between consecutive beats(RR interval or HRV data). It is known as RSA which represents respiration-related HR rhythmic oscillation. Previous studies demonstrated a specific breathing pattern(0.1Hz, 6breaths/min) to improve a physiological body condition related to the stress. In this paper, the level of stress would be evaluated in terms of three phases of the dental treatment, combined with 6breaths/min. Methods: These phases include before, during and after tooth extraction or anesthesia or something.36 patients' stresses were assessed using HRV stress analyzer in each phase in Kangdong Sacred Heart Hospital, and Chuncheon Sacred Heart Hospital, Hallym University Medical Center from Jun. to Sept. of 2007. HRV 5-min data collected were analyzed in time-domain and frequency-domain to evaluate the activity of autonomic nervous system(ANS) which represents the level of stress. Results: All HRV parameters including HF(high frequency), LF(low frequency) and LF/HF ratio showned a significant change affecting the ANS balance. There was a 6.4% difference between R(LF/HF)s on general breathing pattern for balance of Autonomic nervous system, but on controlled breathing pattern, 0.1Hz, was made narrow till 1.4%. The activity of ANS has increased by 1.4% on general breathing pattern, and by 2.9% on controlled breathing pattern, 0.1Hz. Conclusion: After analysis of preoperative stress changes and effect of breathing pattern of 0.1 Hz on the stress in 36 patients who have undergone third molar extraction, following was concluded. In the preoperative stage, the sympathetic change was the greatest?after the?anesthetic injection, and stress was relieved by controlling the breathing pattern to a frequency of 0.1Hz.

• 대한치과보철학회지
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• 제34권1호
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• pp.31-69
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• 1996

The purpose of this investigation was to analyze stress distribution in implant supporting tissue according to different types of attachments such as combination bar attachment, Hader bar attachment, O-Ring attachment and Dal-Ro attachment that are used in mandibular overdenture by using two osseointegrated implants, to study the influence that POM IMC used in bar type attachment has in implant supporting tissue and compare the preceding analyses to find out an effective stress distribution method. Three dimensional photoelastic method was used to obtain the following results. (A) Analysis of stress distribution according to attachment type 1. Under vertical load condition, compressive stress was seen at implant supporting area of working side on all the photoelastic models but in Hader bar attachment tensional stress was seen at distal upper area of implant supporting area. Relatively Hader bar and O-Ring attachment showed even stress distribution pattern. 2. Under vertical load condition, compressive stress at implant apex area and tensional stress at implant lateral supporting area were seen at nonworking side of all models. 3. Under $25^{\circ}$ lateral load condition, general compressive stress was seen at working side implant supporting area in most of the models, especially at distal upper supporting area higher compressive stress concentration was seen in combination bar attachment and tensional stress concentration, in Hader bar attachment. 4. Under $25^{\circ}$ lateral load condition, compressive stress at implant apex area and tensional stress at implant lateral supporting area were seen at nonworking side of all models, except O-Ring model which showed compressive stress only. (B) Influence of POM IMC to stress distribution in bar type attachment 5. Under vertical load condition, better stress distribution pattern was seen at working side of combination bar and Hader bar attachment model using POM IMC. 6. Under vertical load condition, stress value was increased at nonworking side of combination bar attachment model using POM IMC and tendency of increasing compression was seen at nonworking side of Hader bar attachment model using POM IMC. 7. Under $25^{\circ}$ lateral load condition, better stress distribution pattern was seen at working side of combination bar attachment model using POM IMC but tendency of increasing stress was seen on working side of Hader bar attachment model using POM IMC. 8. Under $25^{\circ}$ lateral load condition, stress reduction was seen at nonworking side of combination bar attachment model using POM IMC but tendency of increasing stress was seen at nonworking side of Hader bar attachment model using POM IMC.

• 대한치과보철학회지
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• 제42권4호
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• pp.356-372
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• 2004

Statement of problom: In the internal connection system the loading transfer mechanism within the inner surface of the implant and also the stress distribution occuring to the mandible can be changed according to the abutment form. Therefore it is thought to be imperative to study the difference of the stress distribution occuring at the mandible according to the abutment form. Purpose: The purpose of this study was to assess the loading distributing characteristics of 3 implant systems with internal connection under vertical and inclined loading using finite element analysis. Material and method: Three finite element models were designed according to the type of internal connection of ITI(model 1), Friadent(model 2), and Bicon(model 3) respectively. This study simulated loads of 200N in a vertical direction (A), a $15^{\circ}$ inward inclined direction (B), and a $30^{\circ}$ outward inclined direction (C). Result: The following results have been made based on this numeric simulations. 1. The greatest stress showed in the loading condition C of the inclined load with outside point from the centric cusp tip. 2. Without regard to the loading condition, the magnitudes of the stresses taken at the supporting bone, the implant fixture, and the abutment were greater in the order of model 2, model 1, and model 3. 3. Without regard to the loading condition, greater stress was concentrated at the cortical bone contacting the upper part of the implant fixture, and lower stress was taken at the cancellous bone. 4. The stress of the implant fixture was usually widely distributed along the inner surface of the implant fixture contacting the abutment post. 5. The stress distribution pattern of the abutment showed that the great stress was usually concentrated at the neck of the abutment and the abutment post, and the stress was also distributed toward the lower part of the abutment post in case of the loading condition B, C of the inclined load. 6. In case of the loading condition B, C of the inclined load, the maximum von Misess stress at the whole was taken at the implant fixture both in the model 1 and model 2, and at the abutment in the model 3. 7. The stress was inclined to be distributed from abutment post to fixture in case of the internal connection system. Conclusion: The internal connection system of the implant and the abutment connection methods, the stress-induced pattern at the supporting bone, the implant fixture, and the abutment according to the abutment connection form had differenence among them, and the stress distribution pattern usually had a widely distributed tendency along the inner surface of the implant fixture contacting the a butment post.

• 한국기계가공학회지
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• 제3권3호
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• pp.64-70
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• 2004

The sub-surface stress field beneath the spur gear's contact surface in lubricated condition has been analysed. The surface pressure was obtained by the elasto-hydrodynamic lubrication analysis using the accurate geometric clearances around the contact region of the teeth. The sub-surface stress field was calculated by using the Love's rectangular patch solution. The analysis results show that the sub-surface stress distribution is quite dependent on the surface pressure distribution. The pattern of sub-surface stress field is similar to that of the external load. The depth where the maximum effective stress occurs is not proportional to the intensity of the external load.

• 여성건강간호학회지
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• 제25권4호
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• pp.423-433
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• 2019

Purpose: The study aimed to examine the effects of sleep pattern, stress, and attitude towards menstruation, and behavior that causes a reduction in exposure to endocrine disrupting chemicals (EDCs) in the course of premenstrual syndrome (PMS) in female adolescents. Method: In total, 200 girls attending middle school in K city were recruited via convenience sampling between December 11 and 31, 2018, and 192 subjects were selected for the analysis. Data were analyzed using descriptive statistics, an independent t-test, ANOVA, Pearson's correlation coefficient, and multiple regression. Results: Overall, 9 (4.7%), 152 (79.2%), and 31 (16.1%) students had morning-, intermediate-, and evening-type sleep pattern, respectively. The mean scores for school-related stress were highest. Scores for stress regarding relationships with friends were the lowest. The mean score for attitudes toward menstruation was 72.33 out of 147. The mean score for behavior that led to a reduction in EDCs exposure was 56.57 out of 85. The mean scores for PMS severity were 25.30 and 38.39 out of 60. Analysis of factors affecting PMS revealed that severity of menstrual pain (β=.28), use of analgesics during menstruation (β=.17), family history of PMS (β=-.16), stress (β=.19), and behavior that reduces EDCs exposure (β=-.17) exerted significant effects on PMS. The explanatory power of these variables was 37%. Conclusion: The findings propose the necessity of a health intervention program including educational information, which can reduce PMS in adolescents, induce the behaviors which can decrease exposure to EDCs, and activities for managing the stress levels.

• E2M - 전기 전자와 첨단 소재
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• 제11권11호
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• pp.1-8
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• 1998

This paper presents an arificial neuro-fuzzy technique based prtial discharge (PD) pattern classifier to power system application. This may require a complicated analysis method employ -ing an experts system due to very complex progressing discharge form under exter-nal stress. After referring briefly to the developments of artificical neural network based PD measurements, the paper outlines how the introduction of new emerging technology has resulted in the design of a number of PD diagnostic systems for practical applicaton of residual lifetime prediction. The appropriate PD data base structure and selection of learning data size of PD pattern based on fractal dimentsional and 3-D PD-normalization, extraction of relevant characteristic fea-ture of PD recognition are discussed. Some practical aspects encountered with unknown stress in the neuro-fuzzy techniques based real time PD recognition are also addressed.

• 구강회복응용과학지
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• 제23권1호
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• pp.55-68
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• 2007

The purpose of this study was to analyze the distribution of stress in the surrounding bone around implant placed in the first and second molar region. Two different three-dimensional finite element model were designed according to vertical bone level around fixture ($4.0mm{\times}11.5mm$) on the second molar region. A mandibular segment containing two implant-abutments and a two-unit bridge system was molded as a cancellous core surrounded by a 2mm cortical layer. The mesial and distal section planes of the model were not covered by cortical bone and were constrained in all directions at the nodes. Two vertical loads and oblique loads of 200 N were applied at the center of occlusal surface (load A) or at a position of 2mm apart buccally from the center (load B). Von-Mises stresses were analyzed in the supporting bone. The results were as follows; 1. With the vertical load at the center of occlusal surface, the stress pattern on the cortical and cancellous bones around the implant on model 1 and 2 was changed, while the stress pattern on the cancellous bone with oblique load was not. 2. With the vertical load at the center of occlusal surface, the maximum von-Mises stress appeared in the outer distal side of the cortical bone on Model 1 and 2, while the maximum von-Mises stress appeared in the distal and lingual distal side of the cortical bone with oblique load. 3. With the vertical load at a position of 2 mm apart buccally from the center, there was the distribution of stress on the upper portion of the implant-bone interface and the cortical bone except for the cancellous bone, while there was a distribution of stress on the cancellous bones at the apical and lingual sides around the fixture and on the cortical bone with oblique load. 4. With the changes of the supporting bone on the second molar area, the stress pattern on the upper part of the cortical bone between two implants was changed, while the stress pattern on the cancellous bone was not. The results of this study suggest that establishing the optimum occlusal contact considering the direction and position of the load from the standpoint of stress distribution of surrounding bone will be clinically useful.

• 한국포장학회지
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• 제7권2호
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• pp.25-30
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• 2001

Corrugated board is composed of cellulose fibers which are arranged with the same direction as the board manufactured. The direction is classified with machine direction (MD) and cross-machine direction (CD). Therefore, corrugated board is orthotropic material that has totally different strength properties at each direction and especially, at machine direction, the mechanical properties of fiberboard is superior. The compression strength of the corrugated fiberboard boxes is very important information to the manufacturers and the end users. This study was carried out to design the optimum pattern, size, and location of ventilating hole for ventilating container through the finite element analysis. The optimum pattern and location of ventilating and hand hole were vertical oblong, a short distance to the right and left from the center of panel, and center or a short distance to the top of both sides, respectively. We identified the effect on both stress dispersion and stress level from the analysis of redisigned hand hole.