• Journal of Dental Rehabilitation and Applied Science
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• v.20 no.2
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• pp.71-81
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• 2004

The purpose of this study was to compare the distributing pattern of stress on the finite element models of two units implant prosthesis with one angulated placement of two implant fixtures. The two unit implant crowns simulated to mandibular first and second molars were made. The two kinds of finite element models were designed according to angulation of fixture ($4.0mm{\times}11.5mm$) : Model 1($15^{\circ}$ buccally angulated placement of one fixture on second molar area), Model 2($15^{\circ}$ lingually angulated placement of one fixture on second molar area). Axial loads of 200N were applied to the center of central fossa and to distance of 2mm and 4mm apart from the center of central fossa. Von-Mises stresses were recorded and compared in the fixtures, and buccolingual section of implants. The results were as follows: 1. Under axial loading at the central fossa, the stress was distributed along the straight fixture except apical portion, while on buccally or lingually angulated placement, the highest stresses were concentrated in the neck portion on the opposite side of the angulated fixture. 2. With offset distance increasing, the stresses were concentrated greater in buccal neck of lingually angulated fixture than in lingual neck of buccally angulated fixture. From the above results, in designing of the occlusal scheme for implant prosthesis with the angulated fixture, occlusal contacts should be placed to distribute stress axially in maximum intercuspation and to avoid offset force during eccentric movements.

• 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.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.3
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• pp.246-252
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• 2014

$Br{\aa}nemark^{\prime}s$ original protocol required 4 to 6 months for implant osseointegration before placement of the definitive prosthesis. Although this approach gave very predictable results, it had certain drawbacks. The main disadvantages of this approach were prolonged treatment time, two surgical procedures, placement of a removable prosthesis that required modifications during the course of treatment, and a greater number of appointments. Immediate implant loading is a viable treatment method for selected cases. One of the greatest advantages of this method is the virtual surgery, which precedes the actual clinical treatment and eliminates any need for last minute decisions. The actual surgery time is decreased, since all steps are predetermined. These advantages aren't only more useful for normal patients but also for the mental retardation patients whose cooperation is difficult. This article presents a clinical approach made possible due to the guided implant surgery and CAD/CAM technique.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.4
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• pp.291-296
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• 2003

The use of resonance frequency analysis (RFA) provides a possibility to clinically measure implant stability and osseointegration. The implant stability quotient (ISQ) value of RFA is well known that influenced by effective abutment length and stiffness of the implant in the surrounding tissues. Among these factors stiffness is not accurately defined histologically yet. And the purpose of this study was to find the histolgical relationship of RFA. 17 implants in 3 beagle dogs were used for this study. Among these implants 10 were survived for 7 months, 4 were survived for 3 months and 3 were immediate status after placement. Resonance frequency analyses were conducted and the dogs were sacrificed. Percentage of the bone to implant contact (BIC) in the interface, percentage of the mineralized bone (bone area) within the threads of the implant, and marginal bone level were measured under light microscopy. The correlation between resonance frequency and histomorphometric measurements were analysed and following results were obtained. 1. There was statistically significant correlation between ISQ value and BIC on healed implants. But ISQ value and BIC of all implants were not significantly correlated. (P<0.01) 2. Significant correlation between ISQ value and bone area was not found in this study. 3. There was statistically significant correlation between ISQ value and marginal bone level on all implants as well as on healed implants. (P<0.01).

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.2
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• pp.193-201
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• 2008

In edentulous mandible, implant supported overdenture was considered as a first treatment option. In case of a implant supported telescopic overdenture, sufficient inter-arch space needs for arrangement of artificial teeth and attachment. Passive fit of the implant prosthesis is important factor for preventing mechanical failure. Gold Electroforming System is particularly useful to achieve a passive fit of telescopic attachment and results in precision marginal fit and the small thickness of the coping provides optimal space for narrow inter-arch space. This article presents that application of Gold Electroforming System can provide excellent esthetics and function on four-implant supported telescopic overdenture.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.2
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• pp.183-192
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• 2008

Modern dental reconstructions do not only aim at restoring the patient's mastication, but rather at improving general well-being and quality of life, especially in terms of esthetics. The media, the internet, advertising, and many other facts of society contribute to an increased cosmetic awareness. A 35-year-old male patient presented with as follows: 1) the porcelain fracture of ceramo-metal restoration on #11 and #23, 2) the inclination of incisal plane to horizontal reference plane, 3) the dental midline deviation to facial midline, and 4) the lack of symmetry on upper anterior dentition. The patient requested an aesthetic improvement using fixed prosthodontics including implant-supported restorations. In the upper anterior region, one of the goals of the conventional as well as implant prosthesis is to achieve restorations with the dental attractiveness and beauty in the respect of dental, dentofacial, and facial compositions. This case report presents geometrically improvement of dental esthetics using conventional and implant prosthesis with soft and hard tissue augmentation.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.3
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• pp.283-298
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• 2008

The purpose of this study was to evaluate mechanical fit of fixture- abutment-screw interface in the internal connection implant systems. In this study, each two randomly selected internal implant fixture- abutment assemblys from Certain, Xive, Replace, Ankylos, SS II. were used. The implants were perpendicularly mounted in liquid unsaturated polyester by use of dental surveyor. Each abutment was connected to the implant with recommended torque value using a torque controller. All samples were cross-sectioned with grinder-polisher unit after embeded in liquid unsaturated polyester, and then fixture-abutment-screw interfaces of all samples by using optical microscope and scanning electron microscope were analyzed. Conclusively, although a little variation in machining accuracy and consistency was noted in the samples, important features of all internal connection systems were the deep, internal fixture-abutment connections which provides intimate contact with the implant walls to resist micromovement, resulting in a strong stable interface.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.2
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• pp.184-191
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• 2014

In the mandibular posterior molar area, ridge deficiency is an unfortunate obstacle in the field of implant dentistry. Many techniques are available to rebuild the deficient ridge. Selection and necessity of these techniques are associated with significant morbidity and often require a second surgical site. With the advent of guided bone regeneration (GBR), one may now graft the deficient ridge with decreased morbidity and without a second surgical site. In this case, guided bone regeneration procedures were performed with a combination of allograft, xenograft, and alloplast, excepting autogerous bone at severe defected mandibular alveolar ridge and then placed to the implant successfully. We report that implant placement were good in two cases.

• The Journal of the Korea Contents Association
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• v.14 no.9
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• pp.343-349
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• 2014

The dental osseointegration implant should be enough to endure occlusion load and it's required to have efficient design and use of implant to disperse the stress into bones properly. Solidworks as a finite element analysis program for modeling and analysis of stress distribution was used for the research. The simple crown model was designed on applying conjoined condition with tightening torque of 20 Ncm of a abutment screw between a cement retained implant abutment and a fixture. A $45^{\circ}$ oblique loading from lingual to buccal side on buccal cusps of crown and performed finite element analysis by 100 N of external load. The results by a analysis for stress distribution of supporting bones of fixture were as below. The von Mises stress was concentrated on the upper side of supporting compact bone regardless of the diameters and lengths of fixture, and the efficiency result of stress reduction was increase of fixture's diameter than it's length. Therefore, it's effective to use wider fixture as possible to the conditions of supporting jaw bone.

• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.4
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• pp.321-329
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• 2002

Bending moments results from offset overloading of dental implant, which may cause stress concentrations to exceed the physiological capacity of cortical bone and lead to various kinds of mechanical failures. The purpose of this study was to compare the distributing pattern of stress on the finite element models with the different angulated placement of dental implant in mandibular posterior missing areas. The three kinds of finite element model, were designed according to 3 main configurations: Model 1(parallel typed placement of 2 fixtures), Model 2(15. distal angulated placement of one fixture on second molar area), Model 3(15. mesial angulated placement of one fixture on second molar area). The cemented crowns for mandibular first and second molars were made on the two fixtures (4mm 11.5). Three-dimensional finite element models by two fixtures were constructed with the components of the implant and surrounding bone. A 200N vertical static load were applied to the center of central fossa and the point 2mm apart from the center of central fossa on each model. The preprocessing, solving and postprocessing procedures were done by using FEM analysis software NISA/DISPLAY IV Version 10.0((Engineering Mechanics Research Corporation, USA). Von Mises stresses were evaluated and compared in the supporting bone, fixtures, and abutment. The results were as following : (1) Under the point loading at the central fossa, the direction of angulated fixture affected the stress pattern of implants. (2) Under the offset loading, the position of loading affected more on the stress concentration of implants compare to the angulated direction of implants. The results had a tendency to increase the stress on the supporting bone, fixture and screw under the offset loads when the placement angulation of implant fixture is placed toward mesial or distal direction. In designing of the occlusal scheme for angulated placement, placing the occlusal contacts axially during chewing appears to have advantages in a biomechanical viewpoint.