• Korean Journal of Materials Research
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• v.33 no.8
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• pp.337-343
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• 2023

3Y-TZP (3 mol% yttria-stabilized tetragonal zirconia polycrystals) ceramics have excellent mechanical properties including high fracture toughness, good abrasion resistance as well as chemical and biological stability. As a result, they are widely used in mechanical and medical components such as bearings, grinding balls, and hip implants. In addition, they provide excellent light transmittance, biocompatibility, and can match tooth color when used as a dental implant. Recently, given the materials' resemblance to human teeth, these ceramics have emerged as an alternative to titanium implants. Since the introduction of CAD/CAM in the manufacture of ceramic implants, they've been increasingly used for prosthetic restoration where aesthetics and strength are required. In this study, to improve the surface roughness of zirconia implants, we modified the 3Y-TZP surface with a biocomposite of hydroxyapatite and forsterite using room temperature spray coating methods, and investigated the mixed effect of the two powders on the evolution of surface microstructure, i.e., coating thickness and roughness, and biological interaction during the in vitro test in SBF solution. We compared improvement in bioactivity by observing dissolution and re-precipitation on the specimen surface. From the results of in vitro testing in SBF solution, we confirmed improvement in the bioactivity of the 3Y-TZP substrate after surface modification with a biocomposite of hydroxyapatite and forsterite. Surface dissolution of the coating layer and the precipitation of new hydroxyapatite particles was observed on the modified surface, indicating the improvement in bioactivity of the zirconia substrate.

• Journal of Periodontal and Implant Science
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• v.45 no.3
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• pp.94-100
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• 2015

Purpose: The aim of this study was to investigate the combined effects of physical and chemical surface factors on in vivo bone responses by comparing chemically modified hydrophilic sandblasted, large-grit, acid-etched (modSLA) and anodically oxidized hydrophobic implant surfaces. Methods: Five modSLA implants and five anodized implants were inserted into the tibiae of five New Zealand white rabbits (one implant for each tibia). The characteristics of each surface were determined using field emission scanning electron microscopy, energy dispersive spectroscopy, and confocal laser scanning microscopy before the installation. The experimental animals were sacrificed after 1 week of healing and histologic slides were prepared from the implant-tibial bone blocks removed from the animals. Histomorphometric analyses were performed on the light microscopic images, and bone-to-implant contact (BIC) and bone area (BA) ratios were measured. Nonparametric comparison tests were applied to find any significant differences (P<0.05) between the modSLA and anodized surfaces. Results: The roughness of the anodized surface was $1.22{\pm}0.17{\mu}m$ in Sa, which was within the optimal range of $1.0-2.0{\mu}m$ for a bone response. The modSLA surface was significantly rougher at $2.53{\pm}0.07{\mu}m$ in Sa. However, the modSLA implant had significantly higher BIC than the anodized implant (P=0.02). Furthermore, BA ratios did not significantly differ between the two implants, although the anodized implant had a higher mean value of BA (P>0.05). Conclusions: Within the limitations of this study, the hydrophilicity of the modSLA surface may have a stronger effect on in vivo bone healing than optimal surface roughness and surface chemistry of the anodized surface.

• Journal of Periodontal and Implant Science
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• v.28 no.2
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• pp.321-337
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• 1998

The aims of this study were firstly to investigate soft tissue reactions around single implant-supported crowns and secondly to compare soft tissue dimensions and conditions of the crowns in relation to interdental papillae, and lastly to investigate patients'esthetic satisfaction with their single implant-supported crowns according to the interdental papillae presence/absence. Twenty-nine patients (41 implants) whose single missing tooth in the maxillary anterior region had been replaced by single implant-supported crown participated for the study and various variables of soft tissue conditions, dimensions and crown dimensions were measured around the single implant-supported crowns at clinical examination and from study models and slides. The results showed that the soft tissue conditions around the single implantsupported crowns were similar to those around implants used for partially or totolly edentulous patients. Except for the high frequency of bleeding on probing, all other parameters revealed healthy conditions. The buccal sites of the crown had a shallow pocket comparing with other sites. At all sites of the crown, similar status of little inflammation was found. Mesial sites and central-incisor positioned implantsupported crowns had lower contact point position than distal sites and lateral-incisor positioned crowns, respectively. Mucositis index, probing depth and contact point position were significantly correlated with papillae index(p < 0.05). More inflammation and lower contact point position were found at the implant-supported crown with no interdental space than that with interdental space. Patients showed high esthetic satisfaction regardless of interdental space presence. The result indicated that, despite of their submucosal crown margins, single implantsupported crowns have soft tissue conditions as good as other implants used for the treatment of the different types of edentulism and a clinician can manipulate interdental papilla height by modifying crown shapes within the limits of not violating total esthetics.

• Proceedings of the KACD Conference
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• 2002.11a
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• pp.721-721
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• 2002

For about half a century. dental implants made of titanium have developed as a method of restoration for the tooth loss. In these days. the titanium implants seem to be considered as the alternative for the conventional prosthodontics. But its hard to say that the titanium implants are superior to the treatments that preserve the natural tooth. As this is a general opinion among dentists. the implant will not be able to be the alternative for all the prosthetic treatments. Clinically, there are many causes for extracting tooth. The severe destruction of the tooth structure or periodontal diseases leads to inevitable tooth extraction. When the complete cure is doubtful because of narrow intraoral visibility and improper accessibility in approaching to the tooth and periodontal lesion, we. clinicians often inevitably extract tooth. Passive treatments like conventional restoration, curettage or surgical flap cant be the perfect treatments for the tooth that has subgingival root caries or severe periodontal diseases involved furcation. Many clinicians might have been forced to pull out the relatively healthy tooth by the difficulties of approaching to the lesions and poor prognosis. Though the intentional tooth replantation is performed sometimes. as it doesnt have enough scientific foundation. it has not been considered as a popular treatment method yet. I have been felt keenly the necessity of positive tooth preservation, so I have been attempting the treatment that has new concept. calling Natural Tooth Implantation (NTI) clinically. NTI differs from the tooth replantation in the goal for the treatment and biological healing process. Now. I confirm that NT! is a very positive and valid method of tooth preservation. Like you can get from the name. NTI is the dental implant procedure using natural teeth and similar to the healing process of the titanium implants in many aspects. I have been using biocompatible composite resin. DRM. with NTI and got affirmative clinical results from that. So I would like to introduce.roduce.

• 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.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.3
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• pp.206-213
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• 2011

Purpose: The aim of this study was to evaluate the clinical value of Osstem$^{(R)}$ USII plus system implants. Clinical and radiographic data were analyzed for 88 implants placed and functionally loaded for a 12 month period at the Yonsei University Dental Hospital. Materials and Method: Based on the patient's medical records, clinical factors and their effects on implant marginal bone resorption, distribution and survival rate were analyzed. The marginal bone loss was evaluated at implant placement and during a 6 to 12 months functional loading period. The independent sample t-test was used to evaluate the interrelationship between the factors (${\alpha}$=0.05), and one way repeated measures ANOVA was used to compare the amount of marginal bone resorption. Results: The cumulative survival rate for 88 implants was 100%. The marginal bone resorption from implant placement to prosthetic delivery was 0.24 mm and the average marginal bone resorption from prosthetic delivery to 12 months of functional loading was 0.19 mm. The total average bone resorption from implant placement to 12 months of functional loading was 0.43 mm. There were no statistically differences in the amount of marginal bone resorption when implants were placed in the maxilla or the mandible (P>.05), however, implants placed in the posterior areas showed significantly more marginal bone loss than those placed in the anterior areas (P<.05). Conclusion: Based on these results, the short term clinical success rate of RBM surface treated external connection domestic implants showed satisfactory results and the marginal bone loss was in accord with the success criteria of dental implants.

• Archives of Plastic Surgery
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• v.42 no.3
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• pp.302-308
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• 2015

Background In the literature on nipple-sparing mastectomy (NSM) with one-stage immediate implant reconstruction, contralateral symmetrisation has drawn little attention, with many surgeons still performing standard cosmetic mammaplasty procedures. However, standard implant-based mammaplasty usually does not result in proper symmetry with the mastectomy side, especially regarding breast projection, overall shape, and volume distribution. Methods We retrospectively reviewed 19 consecutive patients undergoing unilateral NSM with immediate prosthetic reconstruction and contralateral simultaneous symmetrisation by using the tailored reduction/augmentation mammaplasty technique between June 2012 and August 2013. Results The average follow-up time was 13 months (range, 10-24 months). No major complications, such as infection, haematoma, and nipple-areola complex necrosis, were experienced. Conclusions Our experience suggests that simultaneous contralateral symmetrisation with tailored reduction/augmentation mammaplasty after unilateral immediate implant reconstruction after NSM facilitates durable and pleasant symmetric outcomes.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.3
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• pp.291-309
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• 2000

Statement of problem. There were several studies on the effects of irradiation to peri-implant bone tissue. However, no clear biological effect of irradiation on peri-implant bone tissue was reported yet. Purpose. This study compared the effect of irradiation on the surrounding tissue of a HA-coated implant fixture with controls. Material and methods. 6 Steri-Oss implants were implanted into the femur of 6 mongrels. The implanted dogs were divided into three groups and received irradiation. After 1 month, 2months and 4 months healing period, the histologic examination and mobility test and digital radiographic imaging analyses were performed to compare the control and experimental group respectively. Results. The irradiated group showed slower healing than control group in light microscopic observations. The mobility test demonstrated significant less number (Periotest) in control group than that of irradiated groups. The digital radiographic imaging analysis showed that the bone density of irradiated group was higher than control group. Conclusion. Generally, control group showed favorable biological response and less mobility than irradiated group. The conflict result of bone density value were measured by the digital radiographic imaging analysis. The digital radiographic imaging analysis needs more research in future.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.4
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• pp.337-358
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• 2007

Purpose This study was performed to evaluate the stability of dual thread implant using resonance frequency analysis in human. Materials and methods Fifty-five patients(32 males and 23 females) with a mean age of 50 years and 1 month who were treated during March, 2005 to July, 2007 in Pusan National University hospital. Totally 145 dual thread Implants were installed and initial stability was measured by Osstell $Mentor^{TM}$. After 3-6 Months, secondary stability was measured at the time of second surgery or before prosthetic treatment. Results At the time of 1st surgery, average ISQ value was $75.12{\pm}12.06$. Only 1 implant was failed during the healing period. Before prosthetic treatment, ISQ values were measured and its mean value was $80.94{\pm}6.12$. Conclusion These results suggest that the increased stability of the implant verifies the clinical relevance of double thread implant.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.2
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• pp.180-186
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• 2017

Implant supported prostheses have improved the quality of lives of totally edentulous patients. However, there are some limitations on the number of implants related to the residual bone level or the economic concern and so on. In this situation, applying fixed detachable prosthesis with bilateral cantilevers can be considered. This clinical report describes implant supported prosthetic rehabilitation of a patient with severe bone resorption. The patient was satisfied and felt comfortable with upper complete denture and lower fixed detachable prosthesis.