• 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 Dental Rehabilitation and Applied Science
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• v.36 no.2
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• pp.121-127
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• 2020

Prosthodontic decision and management should be considered the patient's aesthetic need for anterior teeth in maxillary edentulism. This case report describes 10-year clinical outcome of a maxillary edentulous patient was rehabilitated by means of an implant-supported fixed dental prosthesis (ISFDP) for the anterior region and a distal-extension removable partial denture (RPD) for the posterior region. The ISFDP was designed to splint 4 endosseous implants as one unit and engaged by the RPD. The edentulous mandible was restored by means of an implant-supported overdenture. Over the course, no major adverse event occurred other than wear, discoloration, and breakage of resin veneers and artificial teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.2
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• pp.173-178
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• 2018

The direct metal laser sintering (DMLS) technique would be promising for the full-arch implant-supported restorations due to reduced cost and manufacturing time without potential human errors and casting defects. The aims of this case report were to describe the successful outcome of an implant-supported fixed dental prosthesis in the edentulous maxilla by using the DMLS technology and computer-aided design and computer-aided manufacturing (CAD/CAM) monolithic zirconia crowns, and to describe its clinical implications. A healthy 51-year-old Korean woman visited Seoul National University Dental Hospital and she was in need of a rehabilitation of her entire maxilla due to severe tooth mobility. In this case, all maxillary teeth were extracted and an implant-supported fixed dental prosthesis was fabricated that involved a cobalt-chromium (Co-Cr) framework with the DMLS technique and CAD/CAM monolithic zirconia crowns. Six months after delivery, no distinct mechanical and biological complications were detected and the prosthesis exhibited satisfactory esthetics and function. In this case report, with the DMLS system, the three-dimensional printed prosthesis was created without additional manual tooling and thus, reliable accuracy and passive fit were obtained.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.1
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• pp.71-80
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• 2014

Full-mouth reconstruction of a patient using dental implants is a challenge if there is vertical and horizontal bone resorption. Therefore, it is should be cautious in making the fixed prostheses that restore the function and the esthetics of the gingiva and teeth. In full mouth rehabilitation, CAD/CAM system makes it possible to fabricate restorations with high precision, regardless of span of the restoration. Recently, Palladium-silver (Pd-Ag) alloy which is highly biocompatible and millingable has been developed to compensate for the shortcomings of the titanium or zirconia. This clinical report presents the reconstruction of a maxillary arch with a cement retained implant supported fixed prosthesis using a Pd-Ag alloy generated by CAD/CAM system on eleven osseointegrated implants. The occluding surfaces were made of Pd-Ag alloy, to decrease the risk of chipping or fracture. The prostheses were esthetically pleasing, and no clinical complications have been reported after two years.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.3
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• pp.632-649
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• 1996

The purpose of this study was to examine, by the method of 3-dimentional finite element analysis. how infraocclusion affected the stress distribution in surrounding bone and osseointegrated prosthesis. The 3-dimentional finite element mandibular models were made, in which the first and second molars were removed and the two osseointegrated implants were placed in the first and second molar sites and implant supported fixed prostheses were constructed. Analysis of equivalent stress and displacement induced by strong occlusion or infraocclusion was performed under vertical or inclined distributed loads. The results were as follows; 1. Under vertical load of 50N or 500N, the model in which infraocclusion had not been allowed showed greater stress on implants and the supporting bone than on natural teeth. 2. In the model in which infraocclusion of $30{\mu}m$ had been allowed, implant-prosthesis on the molars had no contact with opposing teeth under vertical load of 50N, However with the same allowed infraocclusion and the model under vertical load of 500N, implant prosthesis on the second molar had contact with opposing teeth, and stress distribution occured properly on natural teeth and implants. 3. Under $45^{\circ}$ inclined load, the model in which infraocclusion had not been allowed showed greater stress on implants and the supporting bone than on natural teeth. There was greater stress in the case of $45^{\circ}$ inclined load than in the case of vertical load. 4. Under $45^{\circ}$ inclined load of 50N or 500N, the model in which infraocclusion of $30{\mu}m$, had been allowed showed no occlusal contact on the implants and occlusal contact on the natural teeth. 5. In partially edentulous cases with implant supported prosthesis, we can prevent excessive load on implants by allowing infraocclusion.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.3
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• pp.288-295
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• 2019

Passive fit of prosthesis is an essential property of implant supported prosthesis for long term success and minimization of complications. And the property is determined mostly by fabrication procedure. There were limitations of extensive implant prosthesis because conventional casting method generate contraction error of long span prosthesis. However, Computer-aided design/Computer-aided manufacturing (CAD/CAM) technology of 3D printing and milling metal framework can overcome those limitations. This case is a full mouth rehabilitation using extensive implant fixed prosthesis. Removable interim prosthesis was made for esthetic, functional evaluation and a guide for implant insertion. After the insertion, implant fixed interim prosthesis was delivered. After additional evaluation and adjustment, final prosthesis was designed with CAD, the fabricated with CAM. Milling technique was used for anterior screw type implant superstructure and 3D printing technique was used for the anterior and posterior implant copings. Fit of the final restoration was favorable. The practitioner and patient were both esthetically and functionally satisfied with the final result.

• Structural Engineering and Mechanics
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• v.55 no.1
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• pp.65-78
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• 2015

In recent years, implants have gained growing importance in all areas of medicine. The success of the treatment depends on many factors affecting the bone-implant, implant-abutment and abutment-prosthesis interfaces. In this paper, static and dynamic behaviors of the dental prosthesis are investigated. Three-dimensional finite element models of dental prosthesis were constructed. Dynamic loads in 5 sec applied on occlusal surface. Therefore, FEA was selected for use in this study to examine the effect of the static and dynamic loads on the stress distribution for an implant-supported fixed partial denture and supporting bone tissue.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.3
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• pp.239-243
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• 2020

When the marginal fit of fixed dental prosthesis decreases, biological and technical complications, such as plaque accumulation, periodontal disease, hypersensitivity, components fracture, cement loss, can happen. The complications affect the long-term success and survival of prostheses. This case report describes a clinical procedure to minimize the marginal gap of implant-supported screw-and-cement retained prosthesis by removing prosthesis-abutment complex and burnishing the interface area. The marginal gap was measured before and after the burnishing using a stereomicroscope and compared. This technique improves the marginal fit, thereby contributing the longevity of the prosthesis.

• The Journal of Advanced Prosthodontics
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• v.13 no.2
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• pp.79-88
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• 2021

Purpose. To assess peri-implant stress distribution using finite element analysis in implant supported fixed partial denture with occlusal schemes of cuspally loaded occlusion and implant protected occlusion. Materials and methods. A 3-D finite element model of mandible with D2 bone with partially edentulism with unilateral distal extension was made. Two Ti alloy identical implants with 4.2 mm diameter and 10 mm length were placed in the mandibular second premolar and the mandibular second molar region and prosthesis was given with the mandibular first molar pontic. Vertical load of 100 N and and oblique load of 70 N was applied on occlusal surface of prosthesis. Group 1 was cuspally loaded occlusion with total 8 contact points and Group 2 was implant protected occlusion with 3 contact points. Results. In Group 1 for vertical load, maximum stress was generated over implant having 14.3552 Mpa. While for oblique load, overall stress generated was 28.0732 Mpa. In Group 2 for vertical load, maximum stress was generated over crown and overall stress was 16.7682 Mpa. But for oblique load, crown stress and overall stress was maximum 22.7561 Mpa. When Group 1 is compared to Group 2, harmful oblique load caused maximum overall stress 28.0732 Mpa in Group 1. Conclusion. In Group 1, vertical load generated high implant stress, and oblique load generated high overall stresses, cortical stresses and crown stresses compared to vertical load. In Group 2, oblique load generated more overall stresses, cortical stresses, and crown stresses compared to vertical load. Implant protected occlusion generated lesser harmful oblique implant, crown, bone and overall stresses compared to cuspally loaded occlusion.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.4
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• pp.497-507
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• 2021

All-on-six concept can be used as one of the treatment options to maximize the use of available residual alveolar bone for implant-supported fixed prosthesis on edentulous patients. But this process is complex and cumbersome. Digital system can be used at multiple steps, from implantation to prosthetic restoration, to overcome this shortcoming. In this case of a maxillary edentulous patient aged 76, digital system was used for restoration of 1-piece design, screw retained fixed prosthesis from diagnosis, implant surgery to fabrication of provisional and final prosthesis. For preoperative diagnosis and treatment planning stage, intra-oral information of a patient was digitalized by direct intra-oral scan. Surgical guide and immediate provisional prosthesis was designed based on this digitalized data. Patient's inconvenience was minimized by applying immediate provisional prosthesis, which was delicately fabricated according to the location data of six implants on most suitable residual alveolar bone. Then, final prosthesis was designed and fabricated going through new interim prosthesis which was newly designed and fabricated, considering patient's requests, stable vertical dimension and occlusion, and esthetic factors using digital system. We hereby report a case successfully applying digital system to multiple steps including implant surgery to fabricating prosthesis, to simplify existing complicated implant treatment procedure to an edentulous patient.