• The Journal of Advanced Prosthodontics
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• v.8 no.5
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• pp.388-395
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• 2016

PURPOSE. The purpose of this study was to evaluate the resistance to deformation under static overloading by measuring yield and fracture strength, and to analyze the failure characteristics of implant assemblies made of different titanium grades and connections. MATERIALS AND METHODS. Six groups of implant assemblies were fabricated according to ISO 14801 (n=10). These consisted of the combinations of 3 platform connections (external, internal, and morse tapered) and 2 materials (titanium grade 2 and titanium grade 4). Yield strength and fracture strength were evaluated with a computer-controlled Universal Testing Machine, and failed implant assemblies were classified and analyzed by optical microscopy. The data were analyzed using the One-way analysis of variance (ANOVA) and Student's t-test with the level of significance at P=.05. RESULTS. The group $IT4_S$ had the significantly highest values and group IT2 the lowest, for both yield strength and fracture strength. Groups $IT4_N$ and ET4 had similar yield and fracture strengths despite having different connection designs. Group MT2 and group IT2 had significant differences in yield and fracture strength although they were made by the same material as titanium grade 2. The implant system of the similar fixture-abutment interfaces and the same materials showed the similar characteristics of deformation. CONCLUSION. A longer internal connection and titanium grade 4 of the implant system is advantageous for static overloading condition. However, it is not only the connection design that affects the stability. The strength of the titanium grade as material is also important since it affects the implant stability. When using the implant system made of titanium grade 2, a larger diameter fixture should be selected in order to provide enough strength to withstand overloading.

• The Journal of the Korean dental association
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• v.52 no.9
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• pp.541-549
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• 2014

The restorative treatment using titanium implants has become a standard procedures in everyday clinical practice. However, there are several concerns about the use of titanium as a materials. Above all, the grayish metal color provokes esthetic problems when the soft tissue around the implants is not optimal. Recently, zirconia has been emerging as an alternative to titanium due to its white color and superior physicochemical properties. In this paper, the current findings about zirconia implants was reviewed based on the results from animal and clinical experiments. In addition, the immediate implantation protocols using the natural tooth form zirconia implants was introduced as a novel procedures and future perspectives were discussed.

• The korean journal of orthodontics
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• v.47 no.4
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• pp.229-237
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• 2017

Objective: The aim of this study was to compare the initial stability as insertion and removal torque and the clinical applicability of novel orthodontic zirconia micro-implants made using a powder injection molding (PIM) technique with those parameters in conventional titanium micro-implants. Methods: Sixty zirconia and 60 titanium micro-implants of similar design (diameter, 1.6 mm; length, 8.0 mm) were inserted perpendicularly in solid polyurethane foam with varying densities of 20 pounds per cubic foot (pcf), 30 pcf, and 40 pcf. Primary stability was measured as maximum insertion torque (MIT) and maximum removal torque (MRT). To investigate clinical applicability, compressive and tensile forces were recorded at 0.01, 0.02, and 0.03 mm displacement of the implants at angles of $0^{\circ}$, $10^{\circ}$, $20^{\circ}$, $30^{\circ}$, and $40^{\circ}$. The biocompatibility of zirconia micro-implants was assessed via an experimental animal study. Results: There were no statistically significant differences between zirconia micro-implants and titanium alloy implants with regard to MIT, MRT, or the amount of movement in the angulated lateral displacement test. As angulation increased, the mean compressive and tensile forces required to displace both types of micro-implants increased substantially at all distances. The average bone-to-implant contact ratio of prototype zirconia micro-implants was $56.88{\pm}6.72%$. Conclusions: Zirconia micro-implants showed initial stability and clinical applicability for diverse orthodontic treatments comparable to that of titanium micro-implants under compressive and tensile forces.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.2
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• pp.210-225
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• 2004

Statement of problem: Implant screw loosening has been remained problem in restorative practices. Surface treatment of screw plays a role of preventing screw from loosening in implant screw mechanism. Purpose : The purpose of this study was to investigate surface characteristics of TiN and ZrN film ion plated screw with titanium and gold alloy screw and to evaluate wear resistance, surface roughness, and film adhesion on screw surface using various instruments. Material and methods : GoldTite screws and titanium screws provided by 3i (Implant Innovation, USA) and TorqTite screws or titanium screws by Steri-Oss (Nobel Biocare, USA) and gold screws and titanium screws by AVANA (Osstem Implant, korea) were selected. Ion plating which is much superior to other surface modification techniques was carried out for gold screws and titanium screws using Ti and Zr coating materials with nitrogen gas. Ion nitrided surface of each abutment screw was observed with field emission scanning electron microscopy (FE-SEM, micro-diamond scratch tester, vickers hardness tester, and surface roughness tester. Results : 1) The surface of gold screw and GoldTite is more smooth than ones of other kinds of non coated screw. 2) The ZrN and TiN coated surface is the more smooth than ones of other kinds of screw. 3) The hardness of TiN and ZrN coated surface showed higher than that of non coated surface. 4) The TiN coated titanium screw and ZrN coated gold screw have a good wear resistance and adhesion on the surface. 5) The surface of ZrN coated screw showed low surface roughness compared with the surface of TiN coated screw. Conclusion : It is considered that the TiN and ZrN coated screw which would prevent a screw from loosening can be applicable to implant system and confirmed that TiN and ZrN film act as lubricant on surface of screw due to decrease of friction for recycled tightening and loosening.

• Journal of Periodontal and Implant Science
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• v.48 no.3
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• pp.182-192
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• 2018

Purpose: The purpose of the present study was to validate an experimental model for assessing tissue integration of titanium and zirconia implants with and without buccal dehiscence defects. Methods: In 3 dogs, 5 implants were randomly placed on both sides of the mandibles: 1) Z1: a zirconia implant (modified surface) within the bony housing, 2) Z2: a zirconia implant (standard surface) within the bony housing, 3) T: a titanium implant within the bony housing, 4) Z1_D: a Z1 implant placed with a buccal bone dehiscence defect (3 mm), and 5) T_D: a titanium implant placed with a buccal bone dehiscence defect (3 mm). The healing times were 2 weeks (one side of the mandible) and 6 weeks (the opposite side). Results: The dimensions of the peri-implant soft tissue varied depending on the implant and the healing time. The level of the mucosal margin was located more apically at 6 weeks than at 2 weeks in all groups, except group T. The presence of a buccal dehiscence defect did not result in a decrease in the overall soft tissue dimensions between 2 and 6 weeks ($4.80{\pm}1.31$ and 4.3 mm in group Z1_D, and $4.47{\pm}1.06$ and $4.5{\pm}1.37mm$ in group T_D, respectively). The bone-to-implant contact (BIC) values were highest in group Z1 at both time points ($34.15%{\pm}21.23%$ at 2 weeks, $84.08%{\pm}1.33%$ at 6 weeks). The buccal dehiscence defects in groups Z1_D and T_D showed no further bone loss at 6 weeks compared to 2 weeks. Conclusions: The modified surface of Z1 demonstrated higher BIC values than the surface of Z2. There were minimal differences in the mucosal margin between 2 and 6 weeks in the presence of a dehiscence defect. The present model can serve as a useful tool for studying peri-implant dehiscence defects at the hard and soft tissue levels.

• The Journal of Advanced Prosthodontics
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• v.6 no.1
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• pp.35-38
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• 2014

PURPOSE. This study aimed to evaluate the correlation between microleakage and screw loosening at different types of implant-abutment connections and/or geometries measuring the torque values before and after the leakage tests. MATERIALS AND METHODS. Three different abutment types (Intenal hex titanium, internal hex zirconium, morse tapered titanium) with different geometries were connected to its own implant fixture. All the abutments were tightened with a standard torque value then the composition was connected to the modified fluid filtration system. After the measurements of leakage removal torque values were re-measured. Kruskal-wallis test was performed for non-parametric and one-way ANOVA was performed for parametric data. The correlation was evaluated using Spearman Correlation Test (${\alpha}=0.05$). RESULTS. Significantly higher microleakage was found at the connection of implant-internal hex zirconium abutment. Observed mean torque value loss was also significantly higher than other connection geometries. Spearman tests revealed a significant correlation between microleakage and screw loosening. CONCLUSION. Microleakage may provoke screw loosening. Removing torque values rationally decrease with the increase of microleakage.

• The Journal of the Korean dental association
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• v.50 no.3
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• pp.126-139
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• 2012

Loss of dentition can lead to not only compromised esthetics and functions of the patient, but also alveolar bone resorption. Bone grafting with prosthetic reconstruction of the gingiva can be selected for the treatment, and it provides many benefits as prosthetic gingival reconstruction does not require a complicated surgical process and is available within a short period of time, with stable clinical results. However, conventional porcelain fused to metal prosthesis has certain limits due to its size, and deformation after several firing procedures. In this clinical report, the author would like to introduce a patient with severe alveolar resorption who was treated with gingiva-shaped zirconia/titanium CAD/CAM implant fixed prosthesis for esthetic and functional rehabilitation. Clinical reports Clinical report 1, 2 : A case of loss of anterior dentition with atrophied alveolar bone. Implant retained zirconia bridge applied with Procera implant bridge system to simulate the gingiva. Upper structure was fabricated with zirconia all ceramic crown. Clinical report 3, 4 : A case of atrophied maxillary alveolus was reconstructed with fixed implant prosthesis, a CAD/CAM designed titanium structure covered wi th resin on its surface. Anterior dentition was reconstructed with zirconia crown. Conclusion and clinical uses. All patients were satisfied with the outcome, and maintained good oral hygiene. Zirconia/titanium implant fixed prosthesis fabricated by CAD/CAM system was highly accurate and showed adequate histological response. No critical failure was seen on the implant fixture and abutment overall. Sites of severe alveolar bone loss can be rehabilitated by implant fixed prosthesis with CAD/CAM system. This type of prosthesis can offer artificial gingival structure and can give more satisfying esthetics and functions, and as a result the patients were able to accept the outcome more fondly, which makes us less than hard to think that it can be a more convenient treatment for the practitioners.

• Journal of Korean society of Dental Hygiene
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• v.4 no.2
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• pp.237-253
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• 2004

This study was to find a patient's motive for receiving implant treatment by age and gender using a self-reporting questionnaire survey with adults(men & women) in Woolsan. The result was as follows: 1. As a result of questionnaire survey with 155 patients in total(86 men, 69 women), 24 of 86 men(27.9%) valued the natural mastication feature of dental implant most, that is as similar as natural teeth, while 18 of 69 women(26.1%) had the most priority over the longer life of implant than common dental prostheses. By age, those in their 20s and 30s had a preference to implant treatment because it does not need to pulling out teeth for prostheses, while those in their 40s and over had a priority to the natural mastication feature of implant that is similar as much as natural teeth. By dental treatment, all of respondents said that the natural mastication feature is the most important in getting dental implant. It was founded that whether one can taste food as it is or not is less important, regardless of age or gender. 2. The greatest obstacle to implant surgery was expensive medical fees, 88 of 155 respondents(56.8%), with a fear of surgery itself being the least obstacle. 3. 90.2% of the total respondents said that they will want to receive dental implant treatment if their economy allow.

• The Journal of the Korean dental association
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• v.54 no.3
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• pp.184-190
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• 2016

The osseointegration of titanium implants has been examined over the past 50 years. Many implant systems have been introduced and have become popular to the implant dentistry. The designs of the connection between implant fixture and abutment are divided into external vs internal connection. From beginning, the $Br{\aa}nemark$ system was characterized by an external hexagon. Internal connection has been developed to reduce stress transferred to the bone. These differences may have impact on the clinical procedures and protocols, laboratory and components costs, and incidence of complications. Therefore, the clinician has to know the different biomechanical features and understand their implications to produce successful implant-supported prosthesis with an external or an internal connection system.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.4
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• pp.519-527
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• 2005

Statement of problem : There are many articles that showed that the magnetism affected the bone formation around titanium implant. It means that a proper magnetism made the osseointegration improved around the implant. So after additional research on the other effect of magnetism on bone formation in implant therapy, we can conclude its possibility of clinical application on implant treatment. Purpose: The purposes of this study were to find out the intensity of magnetic field where magnetism in the titanium implant specimen inserted into the bone could affect the bone formation, and to discover the possibility of clinical application in the areas of dental implants and bone grafts. Material and method: Ten adult male rabbits(mean BW 2Kg) were used in this study. Titanium implant specimens were surgically implanted on the mesial side of the tibia of rabbits. Neodymium magnets(Magnedisc 500, Aichi Steel Corp. Japan) were placed into the implants of experimental group except control group, just after placement of the titanium implants. At 2, 4 and 8 weeks after the surgery, the animals were sacrificed, specimens were obtained and stained with Hematoxylin-Eosin for light microscopic evaluation and histomorphometric analysis. Conclusion : The results were as follows: 1. In radiographic findings, increased radiopacity downward from crestal bone was observed along the titanium implant specimen at experimental period passed by 2, 4, and 8 weeks in both control and experimental group. 2. In histoiogic findings, increased new bone formation was shown in both control and experimental group through the experiment performed for 2, 4, and 8 weeks. More new bone formation and bone remodeling were shown in experimental group. 3. In histomorphometric analysis, the bone contact ratios were 11.9% for control group and 38.5% for experimental group (p<0.05).