• The Journal of Korean Academy of Prosthodontics
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• v.44 no.2
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• pp.197-206
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• 2006

Statement of problem: One of common problems associated with single teeth dental implant prosthetic is the loosening of screws that retain the implants. Purpose: The maintenance of screw joint stability is considered a function of the preload achieved in the screw when the suggested initial tightening torque is applied. The purpose of this study was to investigate acquired preload after initial clamping torque for estimating screw joint stability. Material and methods: A comparative study on the effect of initial clamping of two types of implant systems with different connections was conducted Three dimensional non-linear finite element analysis is adopted to compare the characteristics of screw preloads and stress distributions between two different types of implant systems composed with abutment, screw, and fixture under the same loading and boundary conditions. Results: 1. When the initial clamping torque of 32Ncm was applied to the implant systems, all types of implants generated the maximum effective stress at the first helix region of screw. 2. Morse taper connection types of implants generate lower stress distributions compared to those by butt joint connection types or implants due to large contact surface between abutment and fixture. 3. The internal types of implant systems with friction grip type implant systems have higher resistance to screw loosening than that of the external types of implant systems since the internal types of implant systems generated larger preload than that generated by the external types for the same tightening moments.

• Journal of Technologic Dentistry
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• v.42 no.4
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• pp.348-354
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• 2020

Purpose: Zirconia is differentiated from other ceramics because of its high resistance to corrosion and wear, excellent flexural strength (900~1400 MPa), and high hardness. Dental zirconia with proven mechanical/biological stability is suitable for the manufacture of implants. However, there are limited in vivo studies evaluating stress distribution in zirconia compared with that in titanium implants and studies analyzing finite elements. This study was conducted to evaluate the stress distribution of the supporting bone surrounding zirconia and titanium implants using the finite element analysis method. Methods: For finite element analysis, a single implant-supported restoration was designed. Using a universal analysis program, eight occlusal points were set in the direction of the occlusal long axis. The occlusal load was simulated at 700 N. Results: The zirconia implant (47.7 MPa) von Mises stress decreased by 5.3% in the upper cortical bone compared with the titanium implant (50.2 MPa) von Mises stress. Similarly, the zirconia implant (20.8 MPa) von Mises stress decreased by almost 4% in the cancellous bone compared with the titanium implant (21.7 MPa) von Mises stress. The principal stress in the cortical and cancellous bone exhibited a similar propensity to von Mises stress. Conclusion: In the supporting bone, the zirconia implant is able to reduce bone resorption caused by mechanically transferred stress. It is believed that the zirconia implant can be a potential substitute for the titanium implant by reinforcing aesthetic characteristics and improving stress distribution.

• Journal of Periodontal and Implant Science
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• v.53 no.5
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• pp.388-401
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• 2023

Purpose: This study investigated the accuracy of free-hand implant surgery performed by an experienced operator compared to static guided implant surgery performed by an inexperienced operator on an anterior maxillary dental model arch. Methods: A maxillary dental model with missing teeth (No. 11, 22, and 23) was used for this in vitro study. An intraoral scan was performed on the model, with the resulting digital impression exported as a stereolithography file. Next, a cone-beam computed tomography (CBCT) scan was performed, with the resulting image exported as a Digital Imaging and Communications in Medicine file. Both files were imported into the RealGUIDE 5.0 dental implant planning software. Active Bio implants were selected to place into the model. A single stereolithographic 3-dimensional surgical guide was printed for all cases. Ten clinicians, divided into 2 groups, placed a total of 60 implants in 20 acrylic resin maxillary models. Due to the small sample size, the Mann-Whitney test was used to analyze mean values in the 2 groups. Statistical analyses were performed using SAS version 9.4. Results: The accuracy of implant placement using a surgical guide was significantly higher than that of free-hand implantation. The mean difference between the planned and actual implant positions at the apex was 0.68 mm for the experienced group using the free-hand technique and 0.14 mm for the non-experienced group using the surgical guide technique (P=0.019). At the top of the implant, the mean difference was 1.04 mm for the experienced group using the free-hand technique and 0.52 mm for the non-experienced group using the surgical guide technique (P=0.044). Conclusions: The data from this study will provide valuable insights for future studies, since in vitro studies should be conducted extensively in advance of retrospective or prospective studies to avoid burdening patients unnecessarily.

• 대한치과보철학회:학술대회논문집
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• 1998.05a
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• pp.18-18
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• 1998

• The Journal of the Korean dental association
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• v.37 no.9 s.364
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• pp.636-640
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• 1999

• The Journal of the Korean dental association
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• v.39 no.9 s.388
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• pp.710-715
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• 2001

• The Journal of the Korean dental association
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• v.32 no.10 s.305
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• pp.731-731
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• 1994

• Journal of Technologic Dentistry
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• v.24 no.1
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• pp.145-152
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• 2002

• The Journal of the Korean dental association
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• v.31 no.1 s.284
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• pp.74-79
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• 1993

• Journal of Periodontal and Implant Science
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• v.38 no.2
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• pp.207-214
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• 2008

Purpose: The aim of augmentation of the alveolar ridge is to restore absorbed alveolar ridges for future implant site or esthetic prosthodontic restoration. The present clinical report describes the anterior maxillary augmentation cases using a soft tissue rotated palatal flap, and considers various problems of before and after surgery. Method: First & second patients were treated by vascularized interpositional periosteal-connective tissue(VIP-CT) flap for horizontal soft tissue augmentation. Especially second patient was progressed with bone grafting at the same time. Third patient was treated by the same flap with bone graft and implant placement in single tooth missing premaxillary area. Result: The obtained horizontal augmentation width measured $0.5{\sim}2.7\;mm$. Conclusion: This technique constitutes a viable approach for augmentation the anterior sector of alveolar ridge with the placement of dental implants. But it needs correct diagnosis preparation and careful surgery skill.