• The Journal of Korean Academy of Prosthodontics
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• v.59 no.2
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• pp.201-209
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• 2021

In removable partial dentures, many types of retentive systems have been studied and applied in clinical treatment. One of those systems is the double crown denture system which is widely used in European countries such as Germany and Sweden. Telescopic double crown dentures have several advantages such as convenience in maintaining oral hygiene, enabling to transfer occlusal force along the long axis of the abutment, and secondary splinting effect between the abutments which leads to higher clinical performance compared to conventional removal partial dentures. In this clinical case, the patient was initially restored with a maxillary hybrid telescopic double crown denture with friction pin using remaining natural teeth as abutments. After 7 years, due to lack of recall check-up and poor oral hygiene, the abutment teeth were affected by periodontitis and 4 out of 5 of the abutment teeth had to be extracted. 3 additional implants were placed and the original abutment tooth with the inner crown was maintained. The mandible had fixed prostheses including implants but nevertheless, with strategic implant placement, the patient adapted well and was satisfied with the new maxillary tooth-implant combined double crown denture.

• The Journal of Korean Academy of Prosthodontics
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• v.62 no.2
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• pp.157-164
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• 2024

A variety of digital technologies are being used throughout the entire implant treatment process of diagnosis, surgery, impression, design, and fabrication of prostheses. In this case, using a digital surgical guide, sinus floor elevation was performed without complications, and the implants were placed in the planned position. After the healing period for osseointegration, CAD-CAM (Computer-aided design-Computer-aided manufacturing) customized abutments and provisional prostheses were delivered. While using the provisional prosthesis, occlusal change was observed. To transfer the intermaxillary relationship and abutment position that reflect occlusal change and axial displacement, double scanning and abutment-level digital impressions were taken. Abutment superimposition was used to capture the subgingival margin without gingival retraction. Then, the definitive prosthesis was designed and fabricated with digital system. We report a case applying digital system, to achieve the predictable result as well as the efficient treatment process from implant surgery to fabricating prosthesis in the posterior area.

• Journal of Dental Rehabilitation and Applied Science
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• v.20 no.1
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• pp.9-17
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• 2004

In this study, the biomechanical characteristics of Kimplant were compared with that of Branemark implant by using three dimensional finite element analysis. Two finite element models were fabricated by inserting each implant into the bone model. The bone model was designed to have 18mm height, 13mm width and 15mm length. The size of each implant was planned to have 4mm width and 10mm length. A 200N force was applied on the center of abutment top in three directions - vertical, horizontal and oblique. After analyzing the stresses of fixture and surrounding bone, following results were obtained. 1. There was similar stress distribution between the two models. 2. The magnitude of maximum principal stress on the implant was similar between the two models but the location of maximum principal stress on the implant was different. 3. The magnitude and location of maximum principal stress on the surrounding bone was similar between the two models.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.38 no.6
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• pp.371-378
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• 2012

Many longitudinal studies have reported the successful osseointegration of dental implants, with survival rates approaching 90-95%. However, implants regarded as a "success" may have also failed to undergo osseointegration. A variety of complications and failures have been observed, including implant fracture - a rare and delayed biomechanical complication with serious clinical outcomes. Given the increasing popularity of dental implants, an increase in the number of failures due to late fractures is expected. This study sought to determine the rate of implant fractures and factors associated with its development. This retrospective evaluation analyzed implants placed at Wonkwang Dental Hospital (from 1996 to the present). In our study we found that the frequency of dental implant fractures was very low (0.23%, 8 implant fractures out of 3,500 implants placed). All observed fractures were associated with hybrid-surface threaded implants (with diameter of 4.0 or 3.75 mm). Prosthetic or abutment screw loosening preceded implant fracture in a majority of these cases.

• The Journal of Advanced Prosthodontics
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• v.12 no.1
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• pp.38-48
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• 2020

PURPOSE. The objective of this literature review was to analyze the cumulative survival rates (CSRs) of rigid and non-rigid double-crown-retained removable dental prostheses. MATERIALS AND METHODS. Screening of the literature published from January 1995 to December 2019 was performed by using electronic data base (Pubmed) and manual search. The CSRs of rigid and non-rigid double crown removable dental prostheses were investigated. RESULTS. A total of 403 articles were reviewed and 56 relevant articles of them were selected. Subsequently, 25 articles were included for data extraction. These articles were classified according to rigid and non-rigid type double crowns and further subdivided into teeth, implants, and teeth-implant combination types. The CSRs of rigid type double crown ranged from 68.9% to 95.1% of 5 to 10 years in tooth abutments, 94.02% to 100% over a 3-year mean observation periods in implant abutments, and 81.8% to 97.6% in tooth-implant combination. Non-rigid type double crowns had various CSR ranges from 34% to 94% maximum during 10 years observation in teeth abutment. The CSRs of non-rigid type had over 98% in implant abutments, and ranged from 85% to 100% in tooth-implant combination. CONCLUSION. The CSRs of double crowns varies according to types. With accurate evaluation of the remaining teeth and plan of the strategic implant placement, it could be successful treatment alternatives for partially or completely edentulous patients.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.4
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• pp.364-370
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• 2015

Fixed restoration using implants for patients with posterior partial edentulism is generalized technique. As patient demands increase, the functional and esthetic implant restoration to achieve similar results to lost natural teeth is becoming an important issue. It is inevitable to use customized CAD/CAM abutments rather than ready-made abutments for the creation of implant prosthesis which closely resembles natural teeth. Using CAD/CAM abutment made it possible to obtain natural emergency profiles for posterior implant prostheses, ensuring more comfortable, efficient management of oral hygiene. However, keratinized gingiva with sufficient width and height for a natural emergence profile is required to use a large diameter CAD/CAM abutment which ensures stability and esthetics of hard/soft tissue around the implants. In this case, for esthetical and functional implant zirconia prosthesis, soft tissue graft was performed and customized CAD/CAM abutments were used following ridge augmentation, sinus graft and implantation. Satisfactory results were obtained functionally and esthetically through periodic clinical evaluation, and I hereby report this case.

• The Journal of Advanced Prosthodontics
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• v.6 no.2
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• pp.126-132
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• 2014

PURPOSE. This study was conducted to evaluate the influence of the implant-abutment connection design and diameter on the screw joint stability. MATERIALS AND METHODS. Regular and wide-diameter implant systems with three different joint connection designs: an external butt joint, a one-stage internal cone, and a two-stage internal cone were divided into seven groups (n=5, in each group). The initial removal torque values of the abutment screw were measured with a digital torque gauge. The postload removal torque values were measured after 100,000 cycles of a 150 N and a 10 Hz cyclic load had been applied. Subsequently, the rates of the initial and postload removal torque losses were calculated to evaluate the effect of the joint connection design and diameter on the screw joint stability. Each group was compared using Kruskal-Wallis test and Mann-Whitney U test as post-hoc test (${\alpha}$=0.05). RESULTS. The postload removal torque value was high in the following order with regard to magnitude: two-stage internal cone, one-stage internal cone, and external butt joint systems. In the regular-diameter group, the external butt joint and one-stage internal cone systems showed lower postload removal torque loss rates than the two-stage internal cone system. In the wide-diameter group, the external butt joint system showed a lower loss rate than the one-stage internal cone and two-stage internal cone systems. In the two-stage internal cone system, the wide-diameter group showed a significantly lower loss rate than the regular-diameter group (P<.05). CONCLUSION. The results of this study showed that the external butt joint was more advantageous than the internal cone in terms of the postload removal torque loss. For the difference in the implant diameter, a wide diameter was more advantageous in terms of the torque loss rate.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.4
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• pp.458-467
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• 2016

Cement-retained implant prosthesis has several advantages in the esthetic and occlusal aspects. However, the difficulty of the retrievability and the possibility of peri-implantitis induced by the cement excess would be a threatening factor to the implant prognosis. Peri-implantitis resulting from the remaining cement could occur later on to the patients with periodontitis history. Retention can be controlled by selecting the right cement type. Retention of the cement was the strongest in the resin cement, followed by resin modified glass ionomer cement, poIycarboxylate cement, zinc phosphate cement and glass ionomer cement. Retention of the provisional cement weakened after thermocycling. Other factors such as the abutment number, abutment alignment, height and taper of the abutment can also affect the total retention. To the success of the cement-retained prosthesis, it's important to select the right cement for the clinical purpose. The prosthesis should be fabricated in accordance with the biomechanical requirements. The prosthesis should be cemented with the techniques to reduce the excess cement as much as possible. In addition, the excess cement should be identified using the radiography and carefully removed.

• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.4
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• pp.277-288
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• 2002

Seven finite element models were constructed in mandible having single screw-type implant fixture connected to the premolar superstructure, in order to evaluate how the length, diameter and platform shape of a screw-type fixture influence the stress in the supporting tissue around fixtures. Each finite element model was varied in terms of length, diameter, and platform shape of the fixture. In each model, 250N of vertical load was placed on the central pit of an occlusal plane and 250N of oblique load placed on the buccal cusp. The stress distribution in the supporting tissue and the other components was analysed using 2-dimensional finite element analysis and the maximum von Mises stress in each reference area was compared. Under lateral loading, the stress was larger at the abutment/fixture interface, and in the crestal bone, compared to the stress pattern under vertical loading. The amount of stress at the superstructure was similar regardless of the length, diameter and platform shape of a fixture. Around the longer fixture, the stress was decreased at the bone crest and subjacent cancellous bone and increased in the cancellous bone area apical to the fixture. Around the wider fixture, the stress was decreased at the abutment/fixture interface, and the bone crest and increased in the cancellous bone area apical to the fixture. Around the fixture having wider platform, less stress was produced at the abutment/fixture interface and the upper part of the cortical bone, compared to the fixture having standard platform. In conclusion, the stress distribution of the supporting tissue was affected by length, diameter, and platform shape of a fixture, and the fixture which was larger in diameter and length could reduce the stress in the supporting tissues at the bone-fixture interface and bone crest area.

• The Journal of the Korean dental association
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• v.49 no.2
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• pp.77-84
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• 2011

The benefits of implant supported overdenture are readily apparent for the fully edentulous patients and have been well documented, however, there is deficiency of the studies regarding the combination of implants with removable partial dentures for partially edentulous patients. The purpose of this article is to review the literature concerning implants with removable partial dentures and evaluate the evidence for this clinical approach. Through many clinical case reports and studies we have searched from a broad variety of journals, we present the six considerations needed to contemplate respecting implants with removable partial denture in partially edentulous patients. First, the connection between abutment tooth and removable partial denture has to be rigid and the link between implant and removable partial denture should be hinged. Second, a mesial rest acts better in the point of force distribution for distal extension removable partial denture and splinting between implants is also a favorable choice. Third, T bar has an advantage for implants which are used as abutments in distal extension removable partial denture. Forth, as we all known functional impression is better way to reproduce movement for distal extension removable partial denture. Fifth, indirect retainer and guiding plane on the proximal surfaces of terminal abutment teeth are important in preventing denture base lifting. Sixth, implants in conjunction with removable partial denture is superior in the esthetic and phonetic as well as cost-effective point of view. We also suggest that which place we should install implants for force distribution and which diameter and length of implants should be used. in this review article, we recommend to locate the implant near of the abutment tooth for esthetics or near of first molar position for good stress distribution. The diameter and length of implant also influence to stress distribution. When we compare to conservative partial denture, patients go for removable partial denture using implants due to convenience, better support and retention according to several studies. But it is true that we need to study more on this subject and collect long term follow up cases before we discuss on it. So it is enough to bring this subject into the surface of prosthetic treatment by this article.