• The Journal of Advanced Prosthodontics
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• v.9 no.3
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• pp.143-151
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• 2017

PURPOSE. The design of the attachment must provide an optimum stress distribution around the implant. In this study, for implant overdentures with a bar/clip attachment or a locator attachment, the stress transmitted to the implant in accordance with the change in the denture base length and the vertical pressure was measured and analyzed. MATERIALS AND METHODS. Test model was created with epoxy resin. The strain gauges made a tight contact with implant surfaces. A universal testing machine was used to exert a vertical pressure on the mandibular implant overdenture and the strain rate of the implants was measured. RESULTS. Means and standard deviations of the maximum micro-deformation rates were determined. 1) Locator attachment: The implants on the working side generally showed higher strain than those on the non-working side. Tensile force was observed on the mesial surface of the implant on the working side, and the compressive force was applied to the buccal surface and on the surfaces of the implant on the non-working side. 2) Bar/clip attachment: The implants on the both non-working and working sides showed high strain; all surfaces except the mesial surface of the implant on the non-working side showed a compressive force. CONCLUSION. To minimize the strain on implants in mandibular implant overdentures, the attachment of the implant should be carefully selected and the denture base should be extended as much as possible.

• The Journal of Advanced Prosthodontics
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• v.9 no.5
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• pp.371-380
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• 2017

PURPOSE. The aim of this study is to evaluate and compare the stress distribution in Locator attachments in mandibular two-implant overdentures according to implant locations and different loading conditions. MATERIALS AND METHODS. Four three-dimensional finite element models were created, simulating two osseointegrated implants in the mandible to support two Locator attachments and an overdenture. The models simulated an overdenture with implants located in the position of the level of lateral incisors, canines, second premolars, and crossed implant. A 150 N vertical unilateral and bilateral load was applied at different locations and 40 N was also applied when combined with anterior load at the midline. Data for von Mises stresses in the abutment (matrix) of the attachment and the plastic insert (patrix) of the attachment were produced numerically, color-coded, and compared between the models for attachments and loading conditions. RESULTS. Regardless of the load, the greatest stress values were recorded in the overdenture attachments with implants at lateral incisor locations. In all models and load conditions, the attachment abutment (matrix) withstood a much greater stress than the insert plastic (patrix). Regardless of the model, when a unilateral load was applied, the load side Locator attachments recorded a much higher stress compared to the contralateral side. However, with load bilateral posterior alone or combined at midline load, the stress distribution was more symmetrical. The stress is distributed primarily in the occlusal and lateral surface of the insert plastic patrix and threadless area of the abutment (matrix). CONCLUSION. The overdenture model with lateral incisor level implants is the worst design in terms of biomechanical environment for the attachment components. The bilateral load in general favors a more uniform stress distribution in both attachments compared to a much greater stress registered with unilateral load in the load side attachments. Regardless of the implant positions and the occlusal load application site, the stress transferred to the insert plastic is much lower than that registered in the abutment.

• The Journal of the Korean dental association
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• v.55 no.7
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• pp.457-466
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• 2017

In the case of failed fixed implant prosthesis accompanied by abutment screw fracture, fractured screw fragment must be removed to use the existing implant fixtures. A 61-year-old male patient, who had a failed maxillary fixed implant prosthesis accompanied by three abutment screw fracture, hoped to reconstruct the maxillary implant prosthesis, while maintaining the existing implant fixtures. To use the existing implant fixtures, fractured screw fragments were removed. A maxillary implant overdenture using available existing implants was planned. Bar-attachment with Locator was used for implant splinting, denture stability, and retention. Final impression was taken after treatment of peri-implantitis. Jaw relation registration was taken to evaluate available interarch space for bar-attachment. After fabricating bar-attachment, centric relation was taken. Implant overdenture using bar-attachment with Locator was delivered after wax-denture evaluation. This case report showed that a satisfactory clinical result was achieved by implant overdenture using existing implant fixtures in a maxillary edentulous patient.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.4
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• pp.374-381
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• 2022

This case report introduces a 74-year-old male patient who visited retention deficiency of the mandibular implant overdenture, which was fabricated 20 years ago. When the existing dentures were used, the vertical dimension was reduced, the maxillary complete denture lacked lip support and retention, and the mandibular overdenture lacked clip retention due to damage to the bar attachment. After removing the damaged bar attachment, it was replaced with a ball attachment, and impressions were taken using the DENTCA^TM Tray and then the vertical dimension was measured. The gothic arch tracing was performed to record the centric relation. Obtained impressions were scanned and the shape of final dentures was designed using software and try-in dentures were fabricated using 3D printer. After evaluating the occlusal plane, occlusal relationship, facial shape, and pronunciation using the try-in dentures, the bite registration was recorded, and the final denture was manufactured based on this. The inner surface of the denture was adjusted and bilateral balanced occlusion was formed, and the housing was connected to the mandibular denture by a direct method. This case reports have shown satisfactory resultin recovering improved retention and esthetic outcome by increasing the vertical dimension and the lip support using CAD-CAM technique and the ball attachment.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.1
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• pp.88-97
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• 2002

The purpose of this study was to evaluate a cases which was treated with magnetic attachments on the patients in edentulous mandible and maxilla. Author made magnetic overdenture for two patients and then clinical examination were used for evaluation of the function and change in retention during 30months. Patients showed difficulty in oral hygiene care at the beginning but they go used to it soon. It was effective in promotion of denture retention and stability and also gave patient emotionally uplifting psychologic state. This study suggest that magnetic attachment was effective for the treatment of patients presenting a few remaining teeth or teeth under severe caries or mobility.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.1
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• pp.64-70
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• 2014

The purpose of this case report is to introduce milled titanium bar with Locator$^{(R)}$ that made by CAD/CAM for implant supported overdenture in maxillary edentulous patients. For over 2 years, in terms of function and esthetics, satisfactory result was obtained.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.2
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• pp.169-181
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• 2008

The aim of this study was to compare the retention and stability of implant overdenture according to the shape and the number of magnetic attachment. The experimental groups were designed for the number of implants(1, 2, 4) and shape of magnetic attachments(flat, cushion, dome type) resulting in 9 subgroups. 45 attachments were tested attached to $Br{\aa}nemark$ system implants which were planted on a mandibular model. Each attachment was composed of the magnet assembly embedded in a overdenture sample and the abutment keeper screwed into the implants. Dislodging tensile forces were applied to the overdenture samples using an Instron(cross-head speed 50.80mm/min) in 3 directions simulating function: vertical, oblique, and anterior-posterior. The loading was repeated 10 times in each direction for 45 samples. The values of maximum dislodging force of each subgroup were processed statistically using SPSS V. 12.0 at the 0.05 level of significance. The results of this study were as follows: 1. Flat type magnetic overdenture was the most retentive when subjected to vertically directed forces and dome type was the lest retentive when subjected to obliquely directed forces(p<0.05). 2. In case of planting one implant, flat type had a higher vertically retentive force than anterior-posteriorly retentive force. In case of planting two implants, flat type and dome type had a higher vertically retentive force and in case of planting four implants, flat type and cushion type had a higher vertically retentive force than anterior-posteriorly retentive force(p<0.05). 3. The incremental number of dental implant, without regards to the three types of magnetic attachment shapes, showed higher retention of overdenture(p<0.05). From the results, if a patient need much more retention of implant overdenture, flat type magnetic overdenture would be a good treatment. In case of the bruxism where excessive lateral forces are already present, dome type could be expected to produce better results. In case of planting one implant, flat type is more stable than the other shape of magnet and in case of two implant, flat type and dome type are more stable and in case of four implants, flat type and cushion type are more stable. Planting more than two implants and using flat type magnetic attachment would provide better retention and stability of implant overdenture

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.4
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• pp.581-586
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• 1998

A successful prosthesis is difficult to produce without using the implants in the severely resorbed alveolar ridges and maxillofacial defects. This report describes clinical experience of the overdenture using O-ring attachment. Clinical results have revealed successful application for the O-ring attachment in the two edentulous patients and a partial maxillectomy patient.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.1
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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.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.2
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• pp.127-140
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• 2013

The Locator attachment is used widely for implant retained overdenture. It can be used solitary and needs small vertical space. Locator can be applicable for parallel implants and divergent implants. Nylon male cap allow personalized retention for each case. In this literature review, initial retention force and changes in retention force of various attachments were evaluated. Rotation freedom and stress distribution around the attachment were reviewed. Moreover, patient satisfaction and maintenance care of Locator attachment were described. From all of the researches, it was drawn that Locator attachment can be used successfully and widely in several clinical situations.