• The Journal of Korean Academy of Prosthodontics
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• v.44 no.2
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• pp.174-184
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• 2006

Purpose: Current trend in implant dentistry is changing from external connection to internal connection. To evaluate the splinting of external and internal connection implant on screw loosening, 2-units prosthesis was fabricated with BioPlant $System^(R)$ of external connection type and Lifecore STAGE-1 Single Stage Implant $System^(R)$ of internal connection type. Material and Method: Experimental group is classified into three groups. 1) $G_1-EE$: 2-units prosthesis was fabricated with two Bioplant $System^(R)$ of external connection type. 2) $G_1-EI$: 2-units prosthesis was fabricated with one BioPlant $System^(R)$ of external connection type and one Lifecore STAGE-1 Single Stage Implant $System^(R)$ of internal connection type. 3) $G_1-II$: 2-units prosthesis was fabricated with two Lifecore STAGE-1 Single Stage Implant $System^(R)$ of internal connection type. In fabricating 2-units prosthesis, two hexed abutments are recommended when two implants are installed parallel, otherwise one hexed abutment is used on major occlusal force area and one nonhexed abutment is used on the other area. Since it is rare to find two implants being parallel, it is hard to fabricate prosthesis with passive adaptation using two hexed abutments. It is much more difficult to acquire passive adaptation when using hex abutment compared to nonhex abutment. To evaluate the influence of hexed and nonhexed abutment on screw loosening, 2-units prosthesis was fabricated with hexed and nonhexed abutment. Experimental group is classified into three groups. 1) $G_2-HH$: 2-units prosthesis was fabricated with two hexed abutments. 2) $G_2-HN$: 2-units prosthesis was fabricated with one hexed abutment and one nonhexed abutment. 3) $G_2-NN$: 2-units prosthesis was fabricated with two nonhexed abutments. Result: The results of comparing the detorque value after loading on a each prosthesis periodically are as follows. 1. In splinting group of external and internal connection implant, $G_1-II$ group demonstrated the biggest detorque value, followed by $G_1-EI$ group and $G_1-EE$ group. 2. There is no notable significance between external connection implant of $G_1-EI$ group and $G_1-EE$ group and also no significance between internal connection implant of $G_1-EI$ group and $G_1-II$ group. 3. $G_2-HH$ group showed higher detorque value than $G_2-HN\;and\;G_2-NN$ group. From the results, we can concluded that using both external connection and internal connection implant together is clinically acceptable and in order to acquire a good passive adaptation in fabricating 2-units implant prosthesis we can use two nonhexed abutments.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.4
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• pp.385-393
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• 2009

Statement of problem: High stress concentration on the crestal cortical bone has been regraded as a major etiologic factor jeopardizing long term stability of endosseous implants. Purpose: To investigate if the design characteristics of crestal module, i.e. internal type, external type, and submerged type, affect stress distribution on the crestal cortical bone. Material and methods: A cylindrical shaped implant, 4.3 mm in diameter and 10 mm in length, with 3 different crestal modules, i.e. internal type, external type, and submerged type, were analysed. An axisymmetric scheme was used for finite elment formulation. A vertical load of 50 N and an oblique load of 50N acting at $45^{\circ}$ with the implant's long axis was applied. The peak crestal bone stress acting at the intersection of implant and crestal bone was compared. Results: Under vertical load, the crestal bone stress was high in the order of internal, external, and submerged types. Under the oblique loading condition, it was in the order of internal, submerged, and external types. Conclusion: Crestal module design was found to affect the level of the crestal bone stresses although the actual amount was not significant.

• The Academic Congress of Korean Shoulder and Elbow Society
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• 2005.11a
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• pp.198-205
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• 2005

1. Many design features including suture type, anchor size and geometry, and anchor material, play a role in the overall strength of the anchor. In addition, technical considerations such as implant orientation, pattern, and location may affect the ultimate success of the repair. 2. Multiple fixation points provide a biomechanically sounder construct in Bankart repair. The size of the glenoid and its rim make anchor size a critical consideration in implant selection and implementation.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.3
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• pp.269-281
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• 2008

Fatigue or overload can result in mechanical problems of implant components. The mechanical strength in the implant system is dependent on several factors, such as screw and fixture diameters, material, and design of the fixture-abutment connection and abutment. In these factors, the last rules the strength and stability of the fixture-abutment assembly. There have been some previous reports on the mechanical strength of the fixture-abutment assembly with the compressive bending test or short-term cyclic loading test. However, it is restrictive to predict the long-term stability of the implant system with them. The purpose of this study was to evaluate the influence of the design of the fixture-abutment connection and abutment on the mechanical strength and failure mode by conducting the endurance limit test as well as the compressive bending strength test. Tests were performed according to a specified test(ISO/FDIS 14801) in 4 fixture-abutment assemblies of the Osstem implant system: an external butt joint with Cemented abutment (group BJT), an external butt joint with Safe abutment (group BJS), an internal conical joint with Solid abutment (group CJO), and an internal conical joint with ComOcta abutment (group CJT). The following conclusions were drawn within the limitation of this study. Compressive bending strengths were decreased in order of group BJS(1392.0N), group CJO(1261.8N), group BJT(1153.2N), and group CJT(1110.2N). There were no significant differences in compressive bending strengths between group BJT and group CJT(P>.05). Endurance limits were decreased in order of group CJO(600N), group CJT(453N), group BJS(360N), and group BJT(300N). 3. Compressive bending strengths were influenced by the connection and abutment design of the implant system, however endurance limits were affected more considerably by the connection design.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.3
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• pp.215-223
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• 2010

Purpose: The present study was aimed to evaluate the level of cortical bone strain during the placement of an implant. The primary concern was to investigate if the extent of overloading area near the marginal bone could be affected by microthread fabricated at the cervical 1/3 of an implant. Materials and methods: Three dimensional finite element analysis was used to simulate the insertion of 3 implants. Control model was $4.1{\times}10$ mm implant (Submerged model, Dentis Co,, Daegu, Korea) equipped with a main thread only. Type I was with main thread and microthread, and Type II had similar thread pattern but was of tapered body. A PC-based finite element software (DEFORM 3D ver 5, SFTC, Columbus, OH, USA) was used to calculate a total of 3,600 steps of analysis, which simulated the whole insertion. Results: Results showed that the strain field in the marginal bone within 1 mm of the implant wall was higher than 4,000 micro-strain in the control model. The size of bone overloading was 1-1.5 mm in Type I, and greater than 2 mm in Type II implants. Conclusion: These results indicate that the marginal bone may be at the risk of resorption on receiving the implant for all 3 implant models studied. Yet, the risk was greater for Type I and Type II implants, which had microthread at the cervical 1/3.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.2
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• pp.119-127
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• 2012

Purpose: This study was performed to compare the stress distribution pattern of abutment-fixture connection area using 3-dimensional finite element model analysis when 5 different implant systems which have internal connection. Materials and methods: For the analysis, a finite element model of implant was designed to locate at first molar area. Stress distribution was observed when vertical load of 200 N was applied at several points on the occlusal surfaces of the implants, including center, points 1.5 mm, 3.0 mm away from center and oblique load of 200 N was applied $30^{\circ}$ inclined to the implant axis. The finite element model was analyzed by using of 3G. Author (PlassoTech, California, USA). Results: The DAS tech implant (internal step with no taper) showed more favorable stress distribution than other internally connected implants. AS compare to the situations when the loading was applied within the boundary of implants and an oblique loading was applied, it showed higher equivalent stress and equivalent elastic strain when the loading was applied beyond the boundary of implants. Regardless of loading condition, the abutments showed higher equivalent stress and equivalent elastic strain than the fixtures. Conclusion: When the occlusal contact is afforded, the distribution of stress varies depending on the design of connection area and the location of loading. More favorable stress distribution is expected when the contact load was applied within the diameter of fixtures and the DAS tech implant (internal step with no tapering) has more benefits than the other design of internally connected implants.

• 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.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.2
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• pp.218-224
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• 2017

The implant-supported fixed dental prosthesis in irradiated maxilla needs meticulous treatment planning due to low bone healing capacity. All-on-4 concept implantation can reduce the number of implants to be placed avoiding bone grafting procedure. Conventionally, prefabricated angled abutments for tilted implants have been used. However, in this case, it was replaced with computer-aided design and computer-aided manufacturing (CAD/CAM) abutment. This case report described all-on-4 concept implantation and fabrication of CAD/CAM zirconia fixed dental prostheses using CAD/CAM titanium abutments.

• Journal of Satellite, Information and Communications
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• v.11 no.4
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• pp.21-26
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• 2016

The ESD(electrostatic discharge) protection performance of PPS(PMOS pass structure) embedded N-type silicon controlled rectifier(NSCR_PPS) device with different implant of channel blocking region was discussed for high voltage I/O applications. A conventional NSCR standard device shows low on-resistance, low snapback holding voltage and low thermal breakdown voltage, which may cause latch-up problem during normal operation. However, our proposed NSCR_PPS devices with modified channel blocking structure demonstrate the improved ESD protection performance as a function of channel implant variation. Therefore, the channel blocking implant was a important parameter. Since the modified device with CPS_PDr+HNF structure satisfied the design window, we confirmed the applicable possibility as a ESD protection device for high voltage operating microchips.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.4
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• pp.503-518
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• 2003

Statement of problem : There have been previous studies about considerable variations in machining accuracy and consistency in the implant-abutment-screw interfaces. Purpose : The purpose of this study was to evaluate the machining accuracy and consistency of implant/abutment/screw combinations on two randomly selected implants from each of four manufactures. Material and methods : In this study, screws were respectively used to secure a cemented abutment, to a hexlock implant fixture ; teflon coated titanium alloy screw(Torq-Tite) and titanium alloy screw in Steri--Oss system, gold-plated gold-palladium alloy screw(Gold-Tite) and titanium alloy screw in 3i system gild screw ana titanium screw in AVANA Dental Implant system, and titanium screws in Paragon System. The implants were perpendicularly mounted in polymethyl methacrylate autopolymerizing acrylic resin block(Orthodontic resin, Densply International Inc. USA) by use of dental surveyer. Each abutment screw was secured to the implant with recommended torque value using a digital torque controller. Each screw was again tightened after 10 minutes. All samples were cross sectioned with grinder-polisher unit(Omnilap 2000 SBT Inc) after embeded in liquid unsaturated polyester (Epovia, Cray Valley Inc) Results : There were the largest gaps in the neck areas of screws in hexagonal extension implants which were examined in this study. The leading edge of the abutment screw thread (superior surface) was in contact with the implant body thread, and the majority of the contacting surfaces were localized to the middle portion of the mating threads. Considerable variation in the contacting surfaces was noted in the samples evaluated. Amounts of contact in the abutment screw thread were larger for assemblies with Gold-Tite screw, gold alloy screw. Torq-Tite screw than those with titanium screws. The findings of intimate contact between the screw and screw seat were seen in all samples, regardless of manufacturers. However, microgap between the head and lateral neck surface of the screw and the abutment could be dectected in all samples. The findings of intimate contact between the platform of the implant and the bottom of the abutment were consistent in all samples, regardless of manufacturers. However, microgaps between the lateral surface of external hex of the fixture and the abutment could be dectected in all samples. Conclusion : Considerable variations in machining accuracy and consistency were noted in the samples and the implant-abutment-screw interfaces were incomplete. From the results of this study, further development of the system will be required, including improvements in pattern design.