• The Journal of Korean Academy of Prosthodontics
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• v.58 no.4
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• pp.356-362
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• 2020

All the faculties at the prosthodontic department in Kyung Hee University Dental Hospital at Gangdong, have been implementing the Top-Down concept of treatment approach since 2006 in which the outcomes of the last prosthetic treatment are predicted in advance during the treatment planning stage of patients with dental tissue defects. Based on the Top-Down concept, this report is also an example of how the final prosthetic treatment was performed in advance before going into implant surgery for the missing teeth. Among the various methods of connecting implant fixture and restoration, the cement-retained method is relatively simple to manufacture restoration without being constrained by the angle of the implants placed, but difficult to remove remaining subgingival excess cement completely, and to detach it being when necessary. In the report, SB-locking method will be introduced which enables an aesthetic implant restoration without either a screw hole or residual excess cement.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.1
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• pp.55-62
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• 2017

Overdenture using dental implants could improve the problems of conventional complete denture function which are pain during mastication, insufficient retention and stability. Locator attachment used widely for implant-retained overdenture has advantages that it needs the smallest vertical space and also its nylon male cap allows personalized retention for each case. However its retention force decreases rapidly with function rather than the bar and ball attachment. So, implant fixture should be positioned as parallel as possible.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.41 no.5
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• pp.265-269
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• 2015

The purpose of this study was to investigate implant-supported restoration as a technique for restoring missing teeth in patients with aplastic anemia. Recurrent bleeding from wound sites leads to persistent release of iron in the tissue. Excessive iron in tissue is related to clinical findings, including fibrosis, poor wound healing, and high level of angiogenesis, which are possible etiological factors of reduced osseointegration. A 44-year-old female patient with aplastic anemia was treated with multiple endosseous implants throughout the mandible and in the posterior region of the maxilla. After 14 implants were placed, radiological and clinical parameters were assessed during the follow-up period. Marginal bone did not change significantly during the follow-up period. The fine trabecular bone in intimate contact and enclosing the implant fixture was sufficient for successful osseointegration. None of the 14 implants were associated with compilations during the seven-year experimental period. This study suggests that dental implant procedures are a safe and reliable treatment option for restoration of missing dentition in patients with aplastic anemia.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.35 no.3
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• pp.170-175
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• 2009

Purpose : The purpose of this study is to evaluate 7-year survival rate of implants placed without bone graft in posterior maxilla and compare the survival rate by the age and gender of patient, length and diameter of implant, region of implant placement, bicortical engagement of fixture, and connection of prosthesis. Material and methods : 78 patients (170 implants) who visited our institution from 2002 to 2007 and were followed up with panoramic view and medical records. Kaplan-Meier survival analysis and Log Rank (Mantel-Cox) test were used. Results and conclusions : A 7-year cumulative survival rate for implants placed in posterior maxilla without sinus graft was 95.3%. The survival rate in men was 91.8%, significantly lower than 98.8% in woman.(p<0.05). However, the survival rate by the length of the implants did not show any significant differences.(p>0.05), while the wide platform implant resulted in 85% survival rate which was statistically lower than 98.5% in regular platform. The posterior maxillary implants engaged bicortically showed 97.6% of 7-year Survival rate, comparing 88.6% in not engaged implants. The survival rate of the single implant was 91.2%, while 98.5% in splinted prosthesis. Therefore, the bicortical engagement of the fixtures and splinted prosthesis may be recommended to get a long-term survival rate in posterior maxilla.

• The Journal of Advanced Prosthodontics
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• v.13 no.6
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• pp.396-407
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• 2021

PURPOSE. Zirconia has exceptional biocompatibility and good mechanical properties in clinical situations. However, finite element analysis (FEA) studies on the biomechanical stability of two-piece zirconia implant systems are limited. Therefore, the aim of this study was to compare the biomechanical properties of the two-piece zirconia and titanium implants using FEA. MATERIALS AND METHODS. Two groups of finite element (FE) models, the zirconia (Zircon) and titanium (Titan) models, were generated for the exam. Oblique (175 N) and vertical (175 N) loads were applied to the FE model generated for FEA simulation, and the stress levels and distributions were investigated. RESULTS. In oblique loading, von Mises stress values were the highest in the abutment of the Zircon model. The von Mises stress values of the Titan model for the abutment screw and implant fixture were slightly higher than those of the Zircon model. Minimum principal stress in the cortical bone was higher in the Titan model than Zircon model under oblique and vertical loading. Under both vertical and oblique loads, stress concentrations in the implant components and bone occurred in the same area. Because the material itself has high stiffness and elastic modulus, the Zircon model exhibited a higher von Mises stress value in the abutments than the Titan model, but at a level lower than the fracture strength of the material. CONCLUSION. Owing to the good esthetics and stress controllability of the Zircon model, it can be considered for clinical use.

• Journal of Korean Dental Science
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• v.17 no.2
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• pp.64-74
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• 2024

This case report presents the long-term radiographic outcomes of a novel approach for simultaneous lateral augmentation and implant surgery. A 60-year-old male patient who required tooth extraction of the maxillary central and lateral incisors due to trauma visited the clinic. After tooth extraction, severe horizontal and vertical deficiencies occurred owing to atrophy of the alveolar ridge, and a simultaneous guided bone regeneration (GBR) procedure was planned along with the installation of two implants. In the present case, a modification of the conventional 'sandwich technique' was used by placing the mixture of autogenous bone chips and xenografts at the outermost layer to maximize the osteogenic potential at the coronal part of augmentation while applying solely xenografts at the inner layer. To enhance volumetric stability, an autogenous block of periosteum harvested from the maxillary tuberosity was incorporated between the two layers. Cone-beam computed tomography was performed at baseline and 3 years after the surgery to compare radiographic outcomes. Dehiscence after fixture installation was successfully observed at the re-entry of the surgery site. Three years after the surgery, average horizontal bone gains of 6.11 mm and 4.12 mm were observed in the maxillary central and lateral incisor areas, respectively. Healthy peri-implant mucosa and well maintained marginal bone levels were observed 8 years after the surgery, meeting the criteria for implant success. The findings of this case suggest that a substantial amount of horizontal bone gain can be obtained with a layered approach using autogenous bone materials and xenografts, highlighting the advantages of incorporating autogenous blocks into the simultaneous GBR procedure.

• Journal of Periodontal and Implant Science
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• v.54 no.3
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• pp.177-188
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• 2024

Purpose: Placing dental implants in areas with low bone density or in conditions where bone healing is suppressed is challenging for clinicians. An experiment using a rodent model was performed with the aim of determining the efficacy of host modulation by increasing the systemic level of cholesterol sulfate (CS) using Irosustat in the context of the bone healing process around dental implants. Methods: In 16 ovariectomised female Sprague-Dawley rats, 2 implant fixtures were placed in the tibial bones (1 fixture on each side). At 1 week after surgery, the high-CS group (n=8) received Irosustat-mixed feed, while the control group (n=8) was fed conventionally. Block specimens were obtained at 5 weeks post-surgery for histologic analysis and the data were evaluated statistically (P<0.05). Results: Unlike the high-CS group, half of the specimens in the control group demonstrated severe bone resorption along with a periosteal reaction in the cortex. The mean percentages of bone-to-implant contact (21.5%) and bone density (28.1%) near the implant surface were significantly higher in the high-CS group than in the control group (P<0.05), as was the number of Haversian canals (by 5.3). Conclusions: Host modulation by increasing the CS level may enhance the osseointegration of dental implants placed under conditions of impaired bone healing.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.2
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• pp.99-105
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• 2012

Purpose: The change of the marginal bone around dental implants have significance not only for the functional maintenance but also for the esthetic success of the implant. The purpose of this study was to investigate the load transfer of internal conical joint type implant according to marginal bone resorption by using the three-dimensional finite element analysis model. Materials and methods: The internal conical joint type system was selected as an experimental model. Finite element models of bone/implant/prosthesis complex were constructed. A load of 300 N was applied vertically beside 3 mm of implant axis. Results: The pattern of stress distribution according to marginal bone resorption was similar. The maximum equivalent stress of implant was increase according to marginal bone resorption and the largest maximum equivalent stress was shown at model of 1 mm marginal bone resorption. Although marginal bone loss more than 1mm was occurred increasing of stress, the width of the stress increase was decreasing. Conclusion: According to these results, the exposure of thin neck portion of internal conical joint type implant is most important factor in stress increasing.

• Journal of Technologic Dentistry
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• v.30 no.1
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• pp.25-31
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• 2008

Cp-Ti and Ti-6Al-4V alloys commonly used dental implant materials, particularly for orthopaedic and osteosynthesis because of its suitable mechanical properties and excellent biocompatibility. This alloys have excellent corrosion behavior in the clinical environment. The first factor to decide the success of dental implantation is sufficient osseointegration and high corrosion resistance between on implant fixture and its surrounding bone tissue. In this study, in order to increase corrosion resistance and biocompatibility of Cp-Ti and Ti-6Al-4V alloy that surface of manufactured alloy was coated with TiN by RF-magnetron sputtering method. The electrochemical behavior of TiN coated Cp-Ti and Ti-6Al-4V alloy were investigated using potentiodynamic (EG&G Co, PARSTAT 2273. USA) and potentiostatic test (250mV) in 0.9% NaCl solution at 36.5 $\pm$ 1$^{\circ}C$. These results are as follows : 1. From the microstructure analysis, Cp-Ti showed the acicular structure of $\alpha$-phase and Ti-6Al-4V showed the micro-acicular structure of ${\alpha}+{\beta}$ phase. 2. From the potentiodynamic test, Ecorr value of Cp-Ti and Ti-6Al-4V alloys showed -702.48mV and -319.87mV, respectively. Ti-6Al-4V alloy value was higher than Cp-Ti alloy. 3. From the analysis of TiN and coated layer, TIN coated surface showed columnar structure with 800 nm thickness. 4. The corrosion resistance of TiN coated Cp-Ti and Ti-6Al-4V alloys were higher than those of the non-coated Ti alloys in 0.9% NaCl solution from potentiodynamic test, indicating better protective effect. 5. The passivation current density of TiN coated Cp-Ti and Ti-6Al-4V alloys were smaller than that of the noncoated implant fixture in 0.9% NaCl solution, indicating the good protective effect resulting from more compact and homogeneous layer formation.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.37
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• pp.2.1-2.9
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• 2015

Background: The aim of this study was to evaluate the effect of autogenous tooth bone as a graft material for regeneration of bone in vertical bony defects of the minipigs. Material and Methods: Six minipigs were used in this study. Four molars were extracted in the right mandibular dentition and sent to the Korea Tooth Bank for fabrication of autogenous tooth bone. Ten days later, each extraction site was implanted with MS Implant Narrow Ridge $3.0{\times}10mm$ fixture (Osstem, Seoul, Korea) after standardized 2mm-sized artificial vertical bony defect formation. Pineappleshaped Root-On type autogenous tooth bones were applied to the vertical defects around the neck area of the posterior three fixtures and the fore-most one was not applied with autogenous bone as a control group. Each minipig was sacrificed at 4, 8, 12 weeks after fixture installation and examined radiologically and histologically. Histological evaluation was done under light microscope with Villanueva osteochrome bone staining with semi-quantitative histomorphometric study. Percentage of new bone over total area (NBF) and bone to implant contact (BIC) ratio were evaluated using digital software for area calculation. Result: NBF were $48.15{\pm}18.02%$, $45.50{\pm}28.37%$, and $77.13{\pm}15.30%$ in 4, 8, and 12 weeks, respectively for experimental groups. The control group showed $37.00{\pm}11.53%$, $32.25{\pm}26.99%$, and $1.33{\pm}2.31%$ in 4,8,12 weeks, respectively. BIC ratio were $53.08{\pm}19.82%$, $45.00{\pm}28.37%$, and $75.13{\pm}16.55%$ in 4,8,12 weeks, respectively. Those for the control groups were $38.33{\pm}6.43%$, $33.50{\pm}29.51%$, and $1.33{\pm}2.31%$ in 4, 8, 12 weeks, respectively. Conclusion: Autogenous tooth bone showed higher score than control group in NBF and BIC in all the data encompassing 4,8,12 weeks specimens, but statistically significant only 12 weeks data in both NBF and BIC.