• The Journal of Korean Academy of Prosthodontics
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• v.44 no.5
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• pp.574-583
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• 2006

Statement of problem : The use of permanent magnetics is increasing in implant dentistry. Purpose : This study is to know the effect of permanent magnetics on bone matrix formation of osteoblasts. Materials and methods : The konus abutment-shaped permanent magnetics were connected to the implant fixture, and placed on the culture plate. The osteoblast-like cell Mc3T3E1 were used for cell culture. As the control group, the implants were connected to titanium healing caps, and cultured in the same conditions of experimental group. After 3. 7, 14 days, cells were cultured, and we measured and compared the amount of collagen type I, osteocalcin, which is bone matrix protein by Western immunoblotting analysis. Results: As a result of Western immunoblotting analysis for estimating the amount of bone extracellular matrix, there was no difference between osteoblast of the experimental group and the control group during 3 and 7day-osteoblast culturing. However when cells were cultured for 14days, the amount of bone extracellular matrix was increased, on the experimental group. Conclusion: From these results, magnetic field of permanent magnetics might have effect on bone formation of osteoblast, especially at initial stage of implant placement. Therefore, their clinical application for implant or bone graft could be possible.

• Preventive Nutrition and Food Science
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• v.20 no.4
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• pp.260-265
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• 2015

The purpose of the present study was to investigate the bone-conserving effects of Rubus coreanus-Cheonggukjang (RC-CGJ) supplemented with more intensified phytochemicals compared to general Cheonggukjang (CGJ) in growing rats. Eighteen rats were divided into 3 treatment groups (Control, CGJ, and RC-CGJ) and were given experimental diets for 9 weeks. All of the rats in this study were fed a AIN-93G-based diet. Both CGJ groups were fed with 33.1% CGJ and RC-CGJ powder, respectively. The results of this study indicate that weight gain, mean food intake, and food efficiency ratio were not significantly different by the experimental diets among all groups. Spine bone mineral density (BMD) and femur BMD were not significantly different by the experimental diets. Spine bone mineral content (BMC) was significantly higher in the RC-CGJ and CGJ groups than in the control group, regardless of CGJ type. The femur BMC of the CGJ supplemented group was significantly higher compared with the control group and the RC-CGJ group. Compared with the control group, spine BMD and femur BMD per weight were markedly increased in the RC-CGJ and CGJ group regardless of CGJ type. Also, spine BMC per weight was significantly higher in the RC-CGJ group than in the CGJ group. However, femur BMC per weight was significantly higher in the CGJ group than in the RC-CGJ group. It can be concluded that RC-CGJ and CGJ supplemented diets have more beneficial effects on spine and femur peak bone mass in growing rats.

• Journal of Korean Dental Science
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• v.12 no.1
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• pp.29-37
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• 2019

Purpose: This study was aimed to compare the survival and success rates, and long-term crestal bone loss according to the use of 2 connection types of dental implants (submerged-USII and non-submerged-SSII; Osstem $Implant^{(R)}$) by analyzing the change in alveolar bone height after 1 year under load and during final follow-up period. Materials and Methods: Between December 2004 and August 2008, patients with two types of Osstem implants (USII and SSII) were retrieved retrospectively. A total of 92 patients with 284 implants (USII=60, SSII=224) was finally selected. Their mean follow-up period was 7.5 years. The mesial and distal alveolar crestal bone changes were measured using radiographic images and the average was calculated at 1 year after loading and during final follow-up period. Result: Among the 284 implants, 4 USII and 7 SSII implants were removed, indicating 93.3% and 96.9% survival rates. Of the survived implants, mean crestal bone loss 1 year after loading was 0.39 mm for USII and 0.19 mm for SSII (P=0.018). During the final follow-up, mean crestal bone loss was 0.63 mm and 0.35 mm for USII and SSII, respectively, without statistical significance (P=0.092). According to the criteria for the success and failure of the implant by Albreksson and colleagues, final success rate was estimated as 86.7% for USII and 91.5% for SSII, respectively. Conclusion At 1 year after loading, the average crestal bone loss was significantly different between USII and SSII; however, both types met the criteria for implant success. During the final follow-up, both groups showed insignificant bone resorption patterns and did not show any pathological clinical symptoms. Therefore, both implants exhibited high long-term stability.

• Journal of Periodontal and Implant Science
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• v.52 no.6
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• pp.496-508
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• 2022

Purpose: This study aimed to compare the long-term survival rate and peri-implant marginal bone loss between different types of dental implant-abutment connections. Methods: Implants with external or internal abutment connections, which were fitted at Gangneung-Wonju National University Dental Hospital from November 2011 to December 2015 and followed up for >5 years, were retrospectively investigated. Cumulative survival rates were evaluated for >5 years, and peri-implant marginal bone loss was evaluated at 1- and 5-year follow-up examinations after functional loading. Results: The 8-year cumulative survival rates were 93.3% and 90.7% in the external and internal connection types, respectively (P=0.353). The mean values of marginal bone loss were 1.23 mm (external) and 0.72 mm (internal) (P<0.001) after 1 year of loading, and 1.20 mm and 1.00 mm for external and internal abutment connections, respectively (P=0.137) after 5 years. Implant length (longer, P=0.018), smoking status (heavy, P=0.001), and prosthetic type (bridge, P=0.004) were associated with significantly greater marginal bone loss, and the use of screw-cement-retained prosthesis was significantly associated (P=0.027) with less marginal bone loss. Conclusions: There was no significant difference in the cumulative survival rate between implants with external and internal abutment connections. After 1 year of loading, marginal bone loss was greater around the implants with an external abutment connection. However, no significant difference between the external and internal connection groups was found after 5 years. Both types of abutment connections are viable treatment options for the reconstruction of partially edentulous ridges.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4
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• pp.95-106
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• 1992

This paper presents a comparative evaluation of five different types of steel fibers used as reinforcing material in concrete beams. Two types of plain and RC beams were prepared to compare the relative flexural behavior. The fibers used were dog bone (paddled), both ends hooked. コ-type straight. crimped and wavy type with aspect ratio of 43 to 75. Fiber volume fraction of 1 to 2% were used while shear span to depth ratio (aid) and steel ratio p were fixed. Fiber reinforcement effect index Ef and effective toughness index Te were adopted to evaluate fiber reinforcing effects. The effect of fiber reinforcement on flexural strength is higher in plain beams than in RC beams. Hooked and dog bone type fibers were found to be more effective than the other type ones in enhancing the flexural strength and post-peak energy absorption capacity of concrete beams.

• Structural Engineering and Mechanics
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• v.74 no.4
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• pp.567-576
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• 2020

Considerable controversy surrounds the choice of the best abutment type for implant prosthetics. The two most common structures are hex and non-hex abutments. The non-hex abutment typically furnishes a larger contact area between itself and the implant than that provided by a hex structure. However, when a hex abutment is loaded, the position of its contact area may be deeper than that of a non-hex abutment. Hence, the purpose of this study is to determine the different biomechanical behaviors of an internal bone-level implant based on the abutment type-hex or non-hex-and clinical crown length under static and cyclic loadings using finite element analysis (FEA). The hex structure was found to increase the implant and abutment stability more than the nonhex structure among several criteria. The use of the hex structure resulted in a smaller volume of bone tissues being at risk of hypertrophy and fatigue failure. It also reduced micromovement (separation) between the implant components, which is significantly related to the pumping effect and possible inflammation. Both static and fatigue analyses, used to examine short- and long-term stability, demonstrated the advantages of the hex abutment over the non-hex type for the stability of the implant components. Moreover, although its impact was not as significant as that of the abutment type, a large crown-implant ratio (CIR) increased bone strain and stress in the implant components, particularly under oblique loading.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.1
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• pp.53-67
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• 2002

This study was aimed to analyze the stress distribution of implant and supporting tissue in single tooth implant restoration using Branemark $system^{(R)}$(Nobel Biocare, Gothenberg, Sweden) and Bicon system(Bicon Dental Implants, Boston, MA). Two dimensional finite element analysis model was made at mandibular first premolar area As a crown materials porcelain, ceromer, ADA type III gold alloy were used. Tests have been performed at 25Kgf vertical load on central fossa of crown portion and at 10Kgf load with $45^{\circ}$ lateral direction on cusp inclination. The displacement and stresses of implant and supporting structures were analyzed to investigate the influence of the crown material and the type of implant systems by finite element analysis. The results were obtained as follows : 1. The type of crown material influenced the stress distribution of superstructure, but did not influence that of the supporting alveolar bone. 2. The stress distribution of ceromer and type III gold alloy and porcelain is similar. 3. Stress under lateral load was about twice higher than that of vertical load in all occlusal restorative materials. 4. In Bicon system, stress concentration is similar in supporting bone area but CerOne system generated about 1.5times eater stress more in superstructure material. 5. In Branemark models, if severe occlusal overload is loaded in superstvucture. gold screw or abutment will be fractured or loosened to buffer the occlusal overload but in Bicon models such buffering effect is not expected, so in Bicon model, load can be concentrated in alveolar bone area.

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.2
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• pp.199-215
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• 1990

This study was to analyze the stress distribution of implant and supporting tissue in $Br{\aa}nemark$ osseointegration implant. The analysis has been conducted by using the axisymmetric finite element method and type of model according to crown material. Tests have been performed at 1 kg load on central fossa of crown portion. Each type of model was designed differently according to crown material. 1) Porcelain fused to metal crown(Model A) 2) Composite resin veneered crown(Model B) 3) Acrylic resin veneered crown(Model C) 4) Type III gold crown(Model D) The displacements and stresses of implant and supporting structures were analyzed to investigate the influence of the type of crown material. The results were obtained as follows : 1. Displacement of implant was shown uniformly downward displacement in all models and abutments were observed distally downward displacement. 2. In supporting tissues, stress was concentrated on the crest of compact bone and the spongy bone below implant. 3. The PFM and the type III gold crown showed the largest concentration of stress at the crest of compact bone and the spongy bone below implant, respectively. Acrylic resin artificial teeth and composite resin veneered crown indicated almost the same distribution of stress. 4. The gold screw, the abutment screw and the top of abutment showed the concentration of stress in implants of every model.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.2
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• pp.207-216
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• 2006

Statement of Problem: To conduct a successful function of implant prosthesis in oral cavity for a long time, it is important that not only structure materials must have the biocompatibility, but also the prosthesis must be designed for the stress, which is occurred in occlusion, to scatter adequately within the limitation of alveolar bone around implant and bio-capacity of load support. Now implant which is used in clinical part has a very various shapes, recently the fixture that has tapered form of internal connection is often selected. However the stress analysis of fixtures still requires more studies. Purpose: The purpose of this study is to stress analysis of the implant prosthesis according to the different implant systems using finite element method. Material and methods: This study we make the finite element models that three type implant fixture ; $Br{\aa}nemark$, Camlog, Frialit-2 were placed in the area of mandibular first premolar and prosthesis fabricated, which we compared with stress distribution using the finite element analysis under two loading condition. Conclusion: The conclusions were as follows: 1. In all implant system, oblique loading of maximum Von mises stress of implant, alveolar bone and crown is higher than vertical loading of those. 2. Regardless of loading conditions and the type of system. cortical bone which contacts with implant fixture top area has high stress, and cancellous bone has a little stress. 3. Under the vertical loading, maximum Von mises stress of $Br{\aa}nemark$ system with external connection type and tapered form is lower than Camlog and Frialit-2 system with internal connection type and tapered form, but under oblique loading Camlog and Frialit-2 system is lower than $Br{\aa}nemark$ system.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.40 no.3
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• pp.117-122
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• 2014

Objectives: The purpose of this study was to evaluate the sinus bone graft resorption over 3 years after two-stage implant placement. Materials and Methods: The subjects for this study included 30 patients whose maxillary posterior ridges were too atrophic for implants. Bone-added osteotome sinus floor elevation was used in 15 maxillary sinuses, while the bone graft by lateral approach technique was used in 25 maxillary sinuses. The height from the top of the fixture to the sinus floor was estimated immediately after implant placement and the follow-up period was over 3 years. The surgery was classified with two groups: sinus bone grafting with and without autogenous bone. All implants were placed simultaneously. Results: The mean vertical bone loss was $3.15{\pm}2.95mm$. The survival rate of implants was 94.7%. Conclusion: The amount of bone resorption was not significantly associated with the surgical methods, the type of bone graft materials used, or sinus perforation during surgery.