• Journal of Periodontal and Implant Science
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• 제37권1호
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• pp.45-51
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• 2007

This study evaluated the possibility of the 3-dimensional attachment of human periodontal ligament fibroblasts to a periodntally involved root surface after an EDTA treatment in vitro. The human PDL fibroblasts were isolated from the middle third of the root of periodontally healthy teeth extracted for orthodontic reasons. The cells were cultured in a medium containing Dulbecco's modified Eagle medium supplemented with 10% fetal bovine serum at $37^{\circ}C$ in humidified air containing 5% $CO_2$. Eight single-rooted teeth were obtained from patients diagnosed with periodotitis. After scaling and root planing, four teeth were etched with 24% ethylenediaminetetracetic acid (EDTA) for two minutes (Experimental group). The other four teeth were not treated with EDTA and were used as the control group. The human PDL fibroblasts were placed in the total root surface and cultured for 4 weeks. The teeth were fixed in 2.5% glutaraldehyde in PBS before preparation for the scanning electron microscopy (SEM) examination. The human PDL fibroblasts showed a healthy morphology on the root surfaces treated with EDTA (Experimental group) and a relatively unhealthy appearance on the treated root surfaces (Control group). This suggests that EDTA favorably affects the 3-dimensional attachment of human PDL fibroblasts cultured on the root surfaces. which may play an important role in periodontal healing and regeneration.

• 대한치과보철학회지
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• 제23권1호
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• pp.97-112
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• 1985

The purpose of this study was to evaluate the stress patterns developed in supporting structures by removable partial denture with attachment retainers. The attachments tested were Dalbo(miniature) attachment, resilient Ceka attachment, rigid Ceka attachment, precision and sleeve attachment, and R.P.I. clasp as a contrast. 3-dimensional photoelastic stress analysis was used to record the isochromatic and isoclinic fringe patterns and to calculate principal stress components at measuring points. The results showed that: 1. The maximum compressive stress on residual ridge was produced under the loading point with Dalbo and resilient Ceka attachment, distal to the loading point with rigid Ceka and precision and sleeve attachment, and mesial to the loading point with R.P.I. clasp. 2. The Dalbo attachment produced the most stress on residual ridge, and the least stress on abutment teeth. and resilient Ceka attachment showed favorable stress distribution. 3. Rigid Ceka attachment produced higher compressive stress on buccal. alveolar crest, and precision and sleeve attachment produced higher compressive stress on distal alvelolar crest and mesial surface of the root apex in abutment teeth. 4. R.P.I. clasp produced higher compressive stress on mesial alveolar crest.

• 대한치과보철학회지
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• 제34권1호
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• pp.101-124
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• 1996

In this study, we designed the finite element models of mandible with varying their connecting types between the prosthesis on implant fixture and 2nd premolar, which were free-standing case(Mf), precision attachment case(Mp), semiprecision attachment case(Ms) and telescopic case(Mt). The basic model of the designed finite element models, which contained a canine and the 1st & 2nd premolar, was implanted in the edentulous site of the 1st & 2nd molar by two implant fixtures. We applied the load in all models by two ways. A vertical load of 200N was applied at each central fossa of 2nd premolar and 1st implant. A tilting load of 20N with inclination of $45^{\circ}$ to lingual side was applied to buccal cusp tips of each 2nd premolar and 1st implant. And then we analyzed three-dimensional finite element models, making a comparative study of principal stress and displacement in four cases respectively. Three-dimensional finite element analysis was performed for the stress distribution and the displacement using commercial software(IDEAS program) for SUN-SPARC workstation. The results were as follows : 1 Under vertical load or tilting load, maximum displacement appeared at the 2nd premolar. Semiprecision case showed the largest maximum displacement, and maximum displacement reduced in the order of precision attachment, free-standing and telescopic case. 2. Under vertical load. the pattern of displacement of the 1st implant appeared mesio-inclined because of the 2nd implant splinted together. But displacement pattern of the 2nd premolar varied according to their connection type with prosthesis. The 2nd premolar showed a little mesio-inclined vertical displacement in case of free-standing and disto-inclined vertical displacement due to attachment in case of precision and semiprecision attachment. In telescopic case, the largest mesio-inclined vertical displacement has been shown, so, the 1st premolar leaned mesial side. 3. Under tilting load, The pattern of displacement was similar in all four cases which appeared displaced to lingual side. But, the maximum displacement of 2nd premolar appeared larger than that of the first implant. Therefore, there was large discrepancy in displacement between natural tooth and implant during tilting load. 4. Under vertical load, the maximum compressive stress appeared at the 1st implant's neck. Semiprecision attachment case showed the largest maximum compressive stress, and the maximum compressive stress reduced in the order of precision attachment, telescopic and free-standing case. 5 Under vertical load, the maximum tensile stress appeared at the 2nd implant's distal neck. Semiprecision attachment case showed the largest maximum tensile stress, and the maximum tensile stress reduced in the order of precision attachment, telescopic and free-standing case. 6. Under vertical load or tilting load, principal stress appeared little between natural tooth & implant in free-standing case, but large principal stress was distributed at upper crown and distal contact site of the 2nd premolar in telescopic case. Principal stress appeared large at keyway & around keyway of distal contact site of the 2nd premolar in precision and semiprecision attachment case, appearing more broad and homogeneous in precision attachment case than in semiprecision attachment case.

• 대한치과보철학회지
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• 제36권6호
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• pp.878-887
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• 1998

Although attachments have been utilized for a retainer of removable prostheses during several decades, there is little information on the force distribution by the attachments. This study was undertaken to evaluate the stress patterns developed by partial dentures employing rigid attachments on the supporting structures. Four types of the mandibular removable partial dentures were designed depending upon the position of the rigid attachment and the existency of lingual bracing. Under 100N of vertical and 25N of lateral loads on the 1st and 2nd lower molar of partial denture, stress distribution patterns and displacement were analysed with three dimensional finite element method by ANSYS version 5.3. 1. The highest stresses were concentrated on the distal alveolar crest of posterior abutment and the second stresses on the apical region of posterior abutment in the models. 2. The greatest displacement were shown on the distal alveolar crest of posterior abutment and the second displacement on the distal alveolar crest of anterior abutment in the models. 3. There was little difference between the models with intraoral attachment and those with extracoronal attachment. 4. There was little difference between the models with and without the lingual bracing.

• 대한치과보철학회지
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• 제35권3호
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• pp.577-608
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• 1997

The purpose of this study is to evaluate the stress distribution in the bone around dental implants supporting mandibular overdenture according to the number of implant and the type of attachment. Two or four implants were placed in an edentulous mandibular model and three dimensional photoelastic stress analysis was carried out to measure the fringe order around the implant supporting structure and also to calculate principal stress components at cervical area of each implant. The attachments tested were rigid and resilient type of Dolder bar, Round bar, Hader bar and Dal-Ro attchment. The results were as follows ; 1. In 2-implant supported overdenture using Round bar, Hader bar, and Dal-Ro attachment, compressive stress pattern was observed on the supporting structure of implant on loaded side, while tensile stress pattern in unloaded side. 2. In 2-implant supported overdenture using Dolder bar, the rigid Dolder bar shared the occlusal loads between 2 implants in a more favorable manner than was exhibited by the resilient type, while the resilient type placed a more stress on the distocervical area of the implant on the loaded side. But compressive stress pattern was observed in both the loaded and unloaded sides in either case. 3. In 2-implant supported overdenture, rigid and resilient type of Dolder bar exhibited more cross arch involvement than the Round bar, Hader bar, or Dal-Ro attachment. 4. In 4-implant supported overdenture using resilient Dolder bar and Hader bar, stress turned out to be distributed evenly among the implants between loaded and unloaded side, but thor was no reduction in the magnitude of the stress in the surrounding structure of implant contratry to 2-implant supported overdenture. 5. The stress pattern at cervical area of implant was different with the number of implant or the type of attachment but the overload, harmful to surrounding structure of implant, was not observed.

• Journal of Biosystems Engineering
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• 제30권3호
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• pp.179-184
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• 2005

The purpose of this study was the development of teat-cup attachment module for robot milking system. The teat-cups attachment module was controlled on the two dimensional space independently, Each teat cup of an end effector was independently controlled via two axis control based on the position information data obtained from the image processing system. This system was developed install of all 4 teat cups at the same time after adjusting positions of each teat sequentially. The individual motion system was operated using two servo motors for the high speed of teat position adjustment. The errors fur the individual motion system of teat cups were maximum 1.0mm, minimum 0.0mm, and average 0.6mm. The operating time for adjusting the teat cups position required about 1.0 second. It is envisaged that teat cups attachment module can be applicate to milking robot being developed in consideration of the experiment results for the teat cups operation accuracy and the actuation speed of servo motors.

• The Journal of Advanced Prosthodontics
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• 제12권6호
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• pp.351-360
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• 2020

PURPOSE. The aim of the present study was to compare the stress distributions on the dental implants, abutments, and bone caused by different overdenture attachment types under functional chewing forces. MATERIALS AND METHODS. The 3D finite element models of the mandible, dental implants, attachment types, and prostheses were prepared. In accordance with a conventional dental implant supported overdenture design, the dental implants were positioned at the bone level in the canine teeth region bilaterally. A total of eight models using eight different attachment systems were used in this study. All the models were loaded to simulate chewing forces generated during the centric relationship (450 N), lateral movement (400 N), protrusive movement (400 N), and also in the presence of a food mass unilaterally (200 N). Stress outputs were obtained as the maximum principal stress and the equivalent von-Mises stress. RESULTS. In all attachment types, higher stress values were observed in the abutments, dental implants, and bone in the magnet attachments in different loading conditions. The highest stress values were observed among the magnet systems in the components of the Titanmagnetics model in all loading conditions (stresses were 15.4, 17.7, and 33.1 MPa on abutment, dental implant, and bone, respectively). The lowest stress value was observed in the models of Zest and O-Ring attachments. CONCLUSION. The results of the present study implied that attachment types permitting rotation and tolerating various angles created lower stresses on the bone, dental implants, and abutments.

• 한국생산제조학회지
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• 제5권3호
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• pp.66-72
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• 1996

The applicability of a new method, termed the whirling motion concept, for the improvement of the surface finish in milling three-dimensional sculptured surfaces has been investigated. A method for implementing this concept o conventional NC machines that utilize a suitably configured attachment has been proposed. The tool path equation for the ball-end milling process, based on the surface-shaping system, has been obtained. Both results of the computer simulation and the experiment verified the proposed approach.

• 대한치과보철학회지
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• 제29권2호
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• pp.103-115
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• 1991

This study was executed to analyze the stress distribution of tooth, supporting structure and overdenture by two-dimensional photoelastics when 6 types of coping were inserted. Types of coping were designed to be inclined plane, short dome, medium dome, shore square, medium square and o-p anchor attachment. Fortes were applied respectively as follows: 1) Vertical load of 10 kg on the incisal edge 2) $30^{\circ}$ diagonal load of 8 kg on the labial surface. The results were as follows: 1. In case of short dome and o-p anchor attachment, the stress is evenly distributed on teeth, supporting tissue structure under vertical and $30^{\circ}$ diagonal load, then short dome and o-p anchor attachment show better stress distribution and stabilization of overdenture than any other coping under labial diagonal load. 2. Inclined plane revealed greater tendency of displacement of overdenture than any other coping under labial diagonal load. 3. Long height of copings had greater concentration of stress than short height of copings. 4. In case of medium dome under labial diagonal load, there were high level of stress concentration on denture base contacted labioincisal angle of coping.

• 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.