STATEMENT OF PROBLEM: Recently researches about WC/C (Tungsten Carbide/Carbon) or TiN (Titanium Nitride) coating on abutment screws are going on. It decreases friction coefficient, resistance against corrosion and withdrawal of physical fragility when the coating is applied to the metal surfaces. It is reported that coated abutment screws improved abrasion, adaptability and detorque force. PURPOSE: This study is about the effects of coated abutment screws on loosening of screw and for the purpose of solving the loosening phenomenon of abutment screws which is clinical problem. MATERIAL AND METHODS: Detorque force and surface changes are compared when 10 times of repeated closing and opening are applied to both uncoated titanium abutment screws (Group A) and coated abutment screws with WC/C (Group B) and TiN (Group C). Each group was made up of 10 abutment screws. RESULTS: 1. Before repeated closing and opening, Somewhat rough surface with regular direction was observed in Group A. Coated granules were observed in group B and group C and overall coated layer appeared in regular and smooth form. 2. Before repeated closing and opening, The coated surface showed bigger and thicker size of coated granules in Group C than Group B. 3. After repeated closing and opening, abrasion and deformation of abutment screw surface was observed in Group A and Group B. Exfoliation phenomenon was observed in Group B. 4. Group A showed biggest range of decrease when the weight changes of abutment screws were measured before and after repeated closing and opening. Group C showed less weight changes than Group B but there was no statistical difference between two groups. 5. Group B and Group C showed higher average detorque force than Group A and there was statistical difference. 6. Group A showed more prominent decrease tendency of average detorque force than Group B and Group C. CONCLUSION: Coated abutment screws with WC/C or TiN did not show prominent surface changes than uncoated titanium abutment screws even though they were repeatedly used. And they showed excellent resistance against friction and high detorque force. Thus it is considered that adaptation of WC/C or TiN coating on abutment screws will improve the screw loosening problem.
Corrosion ; Friction ; Tin ; Titanium

STATEMENT OF PROBLEM: A few dry lubricants were applied to abutment screws for the improvement of joint stability. PURPOSE: The purpose of this study was to evaluate the surface change and fit of TiNCoated abutment screw through the examination of tested screws in the field emission scanning electron microscope(FE-SEM;Netherland, Phillips co., model:XL 30 SFEG) after repeated closing and opening. MATERIALS AND METHOD: Titanium(3i/implant Innovations Inc, USA) and Gold-Tite abutment screws(3i/implant Innovations Inc, USA) were selected for Group A and C respectively. TiN coated titanium abutment screws were also divided into two groups, Group B and D. Abutment screws of each group and the fit of abutment screw/implant fixture/abutment were observed on FE-SEM after repeated closing and opening test respectively. RESULTS: 1. The abutment screws of TiN coated groups(Group B and D) showed more remarkable wear resistance in the threads of the screw than those of the other group(Group A and C). 2. There were more severe wear and defect of TiN coating in Group D tightened to 32 Ncm than Group B to 20 Ncm. 3. There was no difference in the fit of abutment screw/fixture/abutment among four groups, Group A, Group B, Group C and Group D. CONCLUSION: Under the conditions of this study, it is suggested that TiN coating of abutment screw be clinically acceptable and be expected to reduce the risk of abutment screw loosening. TiN coating of abutment screw showed good resistance against wear and the adequate fit of abutment screw/implant fixture/abutment.
Joints ; Lubricants ; Tin ; Titanium

STATEMENT OF PROBLEM: Titanium nitride(TiN) coatings are the most general and popular coating method and used to improve the properties of metallic surface for industrial PURPOSEs. When TiN coating applied to the abutment screw, frictional resistance would be reduced, as a results, the greater preload and prevention of the screw loosening could be expected. PURPOSE: The purpose of this study was to investigate mechanical properties of TiN coated film of various coating thickness on the titanium alloy surface and to evaluate proper coating thickness. MATERIAL AND METHOD: 95 Titanium alloy (Ti-6Al-4V) discs of 15 mm in diameter and 3 mm in thickness were prepared for TiN coating and divided into 7 groups in this study. Accoding to coating deposition time (CDT) with TiN by using Arc ion plating, were divided into 7 groups : Group A (CDT 30min), Group B (CDT 60min), Group C (CDT 90min), Group D (CDT 120min), Group E (CDT 150min), Group F(CDT 180min) and Group G (no CDT) as a control group. TiN coating surface was observed with Atomic Force Microscope(AFM), field emission scanning electron microscopy(FE-SEM) and examined with scratch tester, wear tester. Result: 1. Coating thickness for each coated group was increased in proportion to coating deposition time. 2. Surface of all coated groups except Group A was homogeneous and smooth. However, surface of none coated Group G had scratch. 3. Adhesion strength for each coated group was increased in proportion to coating deposition time. 4. Wear resistance for each coated group was increased in proportion to coating deposition time. 5. Surface roughness in Group A, B, C was increased in proportion to coating deposition time. But, surface roughness in Group D, E, F was showed decreased tendency in proportion to coating deposition time. CONCLUSION: According to coating deposition time, mechanical properties of TiN coated film were changed. It was considered that 120 minutes coating deposition time (1.32micrometer in coating thickness) is necessary.
Alloys* ; Friction ; Tin* ; Titanium*

PURPOSE: An investigation has been carried out on the factors which affect the response reading of thermoluminescent dosimeters (TLD-100) loaded with thin material in high energy photon. The aim of the study was to assess the energy response of TLD-100 to the therapeutic ranges of photon beam. MATERIALS AND METHODS: In this technique, TLD-100 (abbreviated as TLD) chips and three different thin material (Tin, Gold, and Tissue equivalent plastic plate) which mounted on the TLD chip were used in the clinical photon beam. The thickness of each metal plates was 0.1 mm and TE plastic plate was 1 mm thick. These compared with the photon energy dependence of the sensitivities of TLD (normal chip), TLD loaded with Tin or Gold plate, for the photon energy range 6 MV to 15 MV, which was of interest in radiotherapy. RESULTS: The enhancement of surface dose in the TLD with metal plate was clearly detected. The TLD chips with a Gold plate was found to larger response by a factor of 1.83 in 10 MV photon beam with respect to normal chip. The sensitivity of TLD loaded with Tin was less than that for normal TLD and TLD loaded with Gold. The relative sensitivity of TLD loaded with metal has little energy dependence. CONCLUSION: The good stability and linearity with respect to monitor units of TLD loaded with metal were demonstrated by relative measurements in high energy photon (6~15 MV) beams. The TLD laminated with metals embedded system in solid water phantom is a suitable detector for relative dose measurements in a small beam size and surface dose.
Metals ; Plastics ; Radiotherapy ; Tin ; Water

STATEMENT OF PROBLEMS: In an attempt to reduce screw loosening, dry lubricant coatings such as pure gold or tefron have been applied to the abutment screw. However, under repeated tightening and loosening procedures, low wear resistance and adhesion strength of coating material produced free particles on the surface of abutment screw and increased frictional resistance resulting in screw tightening problems. PURPOSE: The aim of this study was to compare friction coefficient, adhesion strength, vickers hardness and evaluate coating surface of titanium alloy specimens coated with TiN(titanium nitride), ZrN(zirconium nitride) and WC(tungsten carbide). MATERIAL AND METHOD: Titanium alloy(Ti-6Al-4V) discs of 12mm in diameter and 1mm in thickness divided into 4 groups. TiN, ZrN and WC was coated for the specimens of 3 groups respectively, and those of 1 group were not coated. Each group was made up of 4 specimens. In this study, sputtering method was used among the PVD(Physical Vapor Deposition) techniques available for TiN, ZrN and WC coatings. Friction coefficient, adhesion strength, vickers hardness and coating surface of 4 groups were measured. RESULTS: 1. For all three coating conditions, friction coefficient was significantly decreased. Especially, ZrN coated surface showed the lowest value. TiN(0.39+/-0.02), ZrN(0.24+/-0.01), WC(0.31+/-0.03). 2. TiN coating showed the highest adhesion strength, however ZrN coating had the lowest value. TiN(25.3N+/-1.6), ZrN(14.8N+/-0.6), WC(18.4N+/-0.7). 3. Vickers hardness of all three coatings was remarkably increased as compared with that of none coated specimen. TiN coating had the highest Vickers hardness, however WC coating showed the lowest value. TiN(1865.2+/-33.8), ZrN(1814.4+/-18.6), WC(1008.5+/-35.9). 4. The ZrN or WC coated specimen showed a homogeneous and smooth surface, however the rough surface with defects was observed for TiN coating. CONCLUSIONS: When TiN, ZrN and WC coating applied to the abutment screw, frictional resistance would be reduced, as a result, the greater preload and prevention of the screw loosening could be expected.
Alloys* ; Friction ; Hardness ; Tin* ; Titanium*

The skin sparing effect associated with high energy x-ray or gamma ray beams may be reduce or lost under certain conditions of treatment. Current trends in using large fields. Shield carrying trays, compensating filters, and isocentric methods of treatment have posed problems of increased skin dose which sometimes become a limiting factor in giving adquate tumor doses. We used the shallow ion chamber to measure the phantom surface dose and the physical treatment variables for Co-60 gamma ray, 4MV and 10 MV x-ray beam. The dependence of percent surface dose on field sizes, atomic number of the shielding tray materials and its distance from the surface for 4, 10MV x-rays and Co-60 gamma ray is qualitatively similar. The use of 2 mm thick tin filter is recommended for situations where a low atomic number tray is introduced into the beam at distances less than 15 cm from the surface and with the large field sized for 4 MV x-ray beam. In case of Co-50 gamma ray, the lead glass tray is suitable for enhancement of skin sparing. Also, the filter distance should be as large as possible to achieve substantial skin sparing.
Gamma Rays ; Glass ; Skin* ; Tin

This study was conducted to see the effect of TiN ion-plating on the bond strength of orthodontic bracket. Three stainlesssteel brackets with different base types were chosen; when TiNTion-plated brackets and non ion-plated brackets were bonded to the teeth, initial and long-term bond strength were measured The observations of bonding surface and failure sites through the scanning electron microscope were analysed and compared. The summary of this study was as follows: When TiN ion-plating was not applied, the Micro-Loc type was the highest in bond strength atter 24 hours as 5.89+/-1.77 MPa, followed by 4.27+/-1.12 MPa for Foil Mesh type and 2.64+/-0.58 MPa for Undercut type(P<0.05). Under TiN ion-plating, the bond strength after 24 hours showed: Micro-Loc type - 6.26+/-1.51 MPa, Foil Mesh type - 7.45+/- 2.01 MPa, Undercut type - 2.93+/-0.84 MPa Unlike in the case of non ion-plating, Foil Mesh type showed a higher strength than Micro-Loc type, with Undercut type still showing the lowest bond strength(P<0.05). The bond strength, after 24 hours, increased in case of ion-plated in all 3 types, but a significant increase was shown only in Foil Mesh type(P<0.001). Under a long-term immersion, regardless of ion or non ion-plating, bond strength in general increased over the initial bond strength(one day), with more stability. Through scanning electron microscopic observation of bonding surface, it was found that, regardless of the bracket base type or the application of ion-plating, the resin was thoroughly spreaded into bracket base to form a solid bonding surface between the bracket and the tooth.. This was also true in case of a long-term immersion. The scanning electron microscopic observation of failure sites revealed diverse failure patterns.
Immersion ; Orthodontic Brackets* ; Tin* ; Tooth

The shielding materials designed for replacement of lead equivalent materials for lighter apron than that of lead in diagnostic photon beams. The absorption characteristics of elements were applied to investigate the lead free material for design the shielding materials through the 50 kVp to 110 kVp x-ray energy in interval of 20 kVp respectively. The idea focused to the effect of K-edge absorption of variable elements excluding the lead material for weight reduction. The designed shielding materials composited of Tin 34.1%, Antimon 33.8% and Iodine 26.8% and Polyisoprene 5.3% gram weight account for 84 percent of weight of lead equivalent of 0.5 mm thickness. The size of lead-free shielder was 200x200x1.5 mm3 and 3.2 g/cm3 of density which is equivalent to 0.42 mm of Pb. The lead equivalent of 0.5 mm thickness generally used for shielding apron of diagnostic X rays which is transmitted 0.1% for 50 kVp, 0.9% for 70 kVp and 3.2% for 90 kVp and 4.8% for 110 kVp in experimental measurements. The experiment of transmittance for lead-free shielder has showed 0.3% for 50 kVp, 0.6% for 70 kVp, 2.0% for 90 kVp and 4.2% for 110 kVp within 0.1%. respectively. Using the attenuation coefficient of experiments for 0.5 mm Pb equivalent of lead-free materials showed 0.1%. 0.3%, 1.0% and 2.4%, respectively. Furthermore, the transmittance of lead-free shielder for scatter rays has showed the 2.4% in operation energy of 50 kVp and 5.9% in energy of 110 kVp against 2.4% and 5.1% for standard lead thickness within 0.2% discrepancy, respectively. In this experiment shows the designed lead-free shielder is very effective for reduction the apron weight in diagnostic radiation fields.
Absorption ; Iodine ; Radiation Protection ; Tin ; Weight Loss

STATEMENT OF PROBLEM: Screw loosening has been a common complication and still reported frequently. PURPOSE: The purpose of this study was to evaluate abrasion of the implant fixture and TiN coated abutment screw after repeated delivery and removal with universal measuring microscope. MATERIAL AND METHODS: Implant systems used for this study were Osstem and 3i. Seven pairs of implant fixtures, abutments and abutment screws for each system were selected and all the fixtures were perpendicularly mounted in liquid unsaturated polyesther with dental surveyor. After 20 times of repeated closing and opening test, the evaluation for the change of inner surface of implant and TiN-coated abutment screw, and weight loss were measured. Mann-Whitney test with SPSS statistical software for Window was applied to analyze the measurement of weight loss. RESULTS: TiN-coated abutment screws of Osstem and 3i showed lesser loss of weight than non-coated those of Osstem and 3i (P < .05, Mann-Whitney test). CONCLUSION: Conclusively, TiN coating of abutment screw showed better resistance to abrasion than titanium abutment screw. It was concluded that TiN coating of abutment screw would reduce the loss of preload with good abrasion resistance and low coefficient of friction, and help to maintain screw joint stability.
Collodion ; Friction ; Joints ; Tin ; Titanium ; Weight Loss

STATEMENT OF PROBLEM: When veneering composite resin-metal restoration is prepared, the fact that bond strength between Ti and composite resin is relatively weak should be considered. PURPOSE: The purpose of this study is to evaluate the shear bond strength between the veneering composite resin and commercial pure (CP) Ti / Ti-6Al-4V alloy according to the method of surface treatment. MATERIAL AND METHODS: The disks were cast by two types of metal. Their surfaces were treated by sandblasting, metal conditioner, TiN coating and silicoating respectively. After surface treatment, the disks were veneered by composite resin (Tescera(TM), Bisco, USA) which is 5 mm in diameter and 3 mm in thickness. The specimens were stored in water at 25degrees C for 24 hours, and then evaluated for their shear bond strength by universal testing machine (STM-5(R), United Calibration, USA). These values were statistically analyzed. RESULTS: 1. All methods of surface treatment were used in this study satisfied the requirements of ISO 10477 which is the standard of polymer-based crown and bridge materials. 2. The metal conditioner treated group showed the highest value in shear bond strength of CP Ti, silicoated group, TiN coated group, sandblasted group, in following order. 3. The silicoated group showed the highest value in shear bond strength of Ti-6Al-4V alloy, metal conditioner treated group, sandblasted group, TiN coated group, in following order. CONCLUSION: Within the limitations of this study, all methods of surface treatment used in this study are clinically available.
Alloys ; Calibration ; Collodion ; Crowns ; Tin ; Titanium ; Water