The purpose of this study was to compare the casting problem and corrosion behavior in two types of HL Hexed abutments of the Steri-Oss system : gold/plastic coping and gold coping. The anodic Polarization behavior, the galvanic corrosion between abutments and Type III gold alloys, before and after casting were analyzed, and the crevice corrosion of casting samples was analyzed with the CPPT test and the SEM. The results are as follows ; 1. Anodic polarization behavior of samples ; Before casting, gold/plastic coping and gold coping was shown to have a similar corrosion patterns. TypeIII casting gold alloy was shown to have a lower corrosion potential and passivation film. Corrosion potential of the case of gold/plastic coping after casting was higher than that of gold coping, but the region of passivation film for gold/plastic coping was smaller than that of gold coping. 2. Galvanic corrosion behavior of samples ; Contact current density between casting gold alloys and gold/plastic before casting was higher than that between gold coping and casting gold alloy. Galvanic corrosion of samples after casting was shown to have similar contact current density. 3. Crevice corrosion behavior of samples ; Crevice corrosion resistance of casting sample using gold coping was lower than that of casting sample using gold/plastic coping, and a severe corrosion pattern was observed at the abutment-casting gold alloy interface by the SEM.
Alloys* ; Corrosion* ; Gold Alloys

This study was conducted to investigate the attitude of dietitians on meat products and consumption of meat products in meal service of elementary school. Eight hundred and forty two questionnaires collected from each district of the country were statistically analyzed. Dietitians showed preference of ham and packed meat to other meat products. Dietitians had a good image on meat product regarding it as a good source of protein, imported food and diversely used food for cooking. Whereas 50% and 25.8% of dietitians concerned about the high content of preservative and sodium, respectively. More than 96% of dietitians suggested the food processing company to decrease the addition of preservatives, coloring agents, color formers and sodium. Fifty nine percent of dietitians responded they would increase the consumption of meat product if it is processed to food with low sodium, low cholesterol, low fat and no persavatives. Dietitians used ham for cooking once or twice a month. The reason they used the meat product for meal service was the preference of students and readiness of meat product for cooking. The dietitian's favorite cooking method was roasting ham or sausage with vegetable. Dietitians responded the first thing they checked for purchasing meat product was the date of processing and the term of validity.
Cholesterol ; Coloring Agents ; Cooking ; Food Handling ; Humans ; Meals ; Meat Products* ; Meat* ; Nutritionists* ; Surveys and Questionnaires ; Sodium ; Vegetables

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: Unlike screw-retention type, fixture-abutment retention in Locking taper connection depends on frictional force so it has possibility of abutment to sink. PURPOSE: In this study, Bicon(R) Implant System, one of the conical internal connection implant system, was used with applying loading force to the abutments connected to the fixture. Then the amount of sinking was measured. MATERIAL AND METHODS: 10 Bicon(R) implant fixtures were used. First, the abutment was connected to the fixture with finger force. Then it was tapped with a mallet for 3 times and loads of 20 kg corresponding to masticatory force using loading application instrument were applied successively. The abutment state, slightly connected to the fixture without pressure was considered as a reference length, and every new abutment length was measured after each load's step was added. The amount of abutment sinking (mm) was gained by subtracting the length of abutment-fixture under each loading condition from reference length. RESULTS: It was evident, that the amount of abutment sinking in Bicon(R) Implant System increased as loads were added. When loads of 20 kg were applied more than 5 - 7 times, sinking stopped at 0.45 +/- 0.09 mm. CONCLUSION: Even though locking taper connection type implant shows good adaption to occlusal force, it has potential for abutment sinking as loads are given. When locking taper connection type implant is used, satisfactory loads are recommended for precise abutment location.
Bite Force ; Fingers ; Friction ; Retention (Psychology)

No abstract available.
Pregnancy* ; Spermatozoa*

PURPOSE: The aim of this study was to evaluate the clinical performance of screw- and cement-retained implant prosthesis (SCP) design in terms of retained preload of abutment screws and cement washout. MATERIALS AND METHODS: Patients with the partial posterior edentulous areas comprised the study group. Implants were placed, and SCPs were delivered after 3 to 6 months healing. Follow-up examinations were performed. The implant survival rate and the prosthetic success rate were evaluated. The retained preload ratio of abutment screws and the prosthetic decementation ratio were measured. RESULTS: Twenty one SCPs (forty three implants)in twenty patients were followed up to 64 months. All of the implants survived during the follow-up period (mean follow-up: 34 months). The prosthetic success rate was 100 % considering no abutment, screw, porcelain or metal frame fractures, as well as no screw loosening. The retained preload ratio of SCPs at the end of follow-up period was 97.61% (+/-16.29) and the decementation ratio was 9.5 %. CONCLUSION: Within the limitations of this clinical study, SCP design showed favorable short-term clinical performances in respect of screw loosening and cement washout.
Dental Cements ; Dental Porcelain ; Dental Prosthesis Design ; Dental Prosthesis, Implant-Supported ; Follow-Up Studies ; Humans ; Prostheses and Implants* ; Survival Rate

PURPOSE: The emergence profile concept of an implant restoration is one of the most important factors for the esthetics and health of peri-implant soft tissue. This paper reports on two cases of gingival recontouring by the fabrication of a provisional implant restoration to produce an optimal emergence profile of a definitive implant restoration. METHODS: After the second surgery, a preliminary impression was taken to make a soft tissue working cast. A provisional crown was fabricated on the model. The soft tissue around the implant fixture on the model was trimmed with a laboratory scalpel to produce the scalloped gingival form. Light curing composite resin was added to fill the space between the provisional crown base and trimmed gingiva. After 4 to 6 weeks, the final impression was taken to make a definitive implant restoration, where the soft tissue and tooth form were in harmony with the adjacent tooth. RESULTS: At the first insertion of the provisional restoration, gum bleaching revealed gingival pressure. Four to six weeks after placing the provisional restoration, the gum reformed with harmony between the peri-implant gingiva and adjacent dentition. CONCLUSIONS: Gingival recontouring with a provisional implant restoration is a non-surgical and non-procedure-sensitive method. The implant restoration with the optimal emergence profile is expected to provide superior esthetic and functional results.
Crowns ; Dental Implants ; Dental Restoration Repair ; Esthetics ; Gingiva ; Light ; Pectinidae ; Tooth

PURPOSE: The purpose of this study was to investigate the corrosion behaviors of dental implant alloy after micro-sized surface modification in electrolytes containing Mn ion. MATERIALS AND METHODS: Mn-TiO₂ coatings were prepared on the Ti-6Al-4V alloy for dental implants using a plasma electrolytic oxidation (PEO) method carried out in electrolytes containing different concentrations of Mn, namely, 0%, 5%, and 20%. Potentiodynamic method was employed to examine the corrosion behaviors, and the alternating-current (AC) impedance behaviors were examined in 0.9% NaCl solution at 36.5℃±1.0℃ using a potentiostat and an electrochemical impedance spectroscope. The potentiodynamic test was performed with a scanning rate of 1.667 mV s⁻¹ from −1,500 to 2,000 mV. A frequency range of 10⁻¹ to 10⁵ Hz was used for the electrochemical impedance spectroscopy (EIS) measurements. The amplitude of the AC signal was 10 mV, and 5 points per decade were used. The morphology and structure of the samples were examined using field-emission scanning electron microscopy and thin-film X-ray diffraction. The elemental analysis was performed using energy-dispersive X-ray spectroscopy. RESULT: The PEO-treated surface exhibited an irregular pore shape, and the pore size and number of the pores increased with an increase in the Mn concentration. For the PEO-treated surface, a higher corrosion current density (I(corr)) and a lower corrosion potential (E(corr)) was obtained as compared to that of the bulk surface. However, the current density in the passive regions (I(pass)) was found to be more stable for the PEO-treated surface than that of the bulk surface. As the Mn concentration increased, the capacitance values of the outer porous layer and the barrier layer decreased, and the polarization resistance of the barrier layers increased. In the case of the Mn/Ca-P coatings, the corroded surface was found to be covered with corrosion products. CONCLUSION: It is confirmed that corrosion resistance and polarization resistance of PEO-treated alloy increased as Mn content increased, and PEO-treated surface showed lower current density in the passive region.
Alloys ; Corrosion ; Dental Implants ; Dielectric Spectroscopy ; Electric Impedance ; Electrolytes ; Manganese ; Methods ; Microscopy, Electron, Scanning ; Plasma ; Spectrum Analysis ; X-Ray Diffraction

PURPOSE: The aim of this study was to compare the color stability, water sorption and cytotoxicity of thermoplastic acrylic resin for the non-metal clasp dentures to those of thermoplastic polyamide and conventional heat-polymerized denture base resins. MATERIALS AND METHODS: Three types of denture base resin, which are conventional heat-polymerized acrylic resin (Paladent 20), thermoplastic polyamide resin (Bio Tone), thermoplastic acrylic resin (Acrytone) were used as materials for this study. One hundred five specimens were fabricated. For the color stability test, specimens were immersed in the coffee and green tee for 1 and 8 weeks. Color change was measured by spectrometer. Water sorption was tested after 1 and 8 weeks immersion in the water. For the test of cytotoxicity, cell viability assay was measured and cell attachment was analyzed by FE-SEM. RESULTS: All types of denture base resin showed color changes after 1 and 8 weeks immersion. However, there was no significant difference between denture base resins. All specimens showed significant color changes in the coffee than green tee. In water sorption test, thermoplastic acrylic resin showed lower values than conventional heat-polymerized acrylic resin and thermoplastic polyamide resin. Three types of denture base showed low cytotoxicity in cell viability assay. Thermoplastic acrylic resin showed the similar cell attachment but more stable attachment than conventional heat-polymerized acrylic resin. CONCLUSION: Thermoplastic acrylic resin for the non-metal clasp denture showed acceptable color stability, water sorption and cytotoxicity. To verify the long stability in the mouth, additional in vitro studies are needed.
Cell Survival ; Coffee ; Denture Bases ; Dentures* ; Immersion ; Mouth ; Nylons ; Water*

STATEMENT OF PROBLEM: There have been previous studies about considerable variations in machining accuracy and consistency in the implant-abutment-screw interfaces. PURPOSE: The purpose of this study was to evaluate the machining accuracy and consistency of implant/abutment/screw combinations on two randomly selected implants from each of four manufactures. MATERIAL AND METHODS: In this study, screws were respectively used to secure a cemented abutment to a hexlock implant fixture; teflon coated titanium alloy screw(Torq-Tite) and titanium alloy screw in Steri-Oss system, gold-plated gold-palladium alloy screw(Gold-Tite) and titanium alloy screw in 3i system, gold screw and titanium screw in AVANA Dental Implant system, and titanium screws in Paragon System. The implants were perpendicularly mounted in polymethyl methacrylate autopolymerizing acrylic resin block(Orthodontic resin, Densply International Inc. USA) by use of dental surveyer. Each abutment screw was secured to the implant with recommended torque value using a digital torque controller. Each screw was again tightened after 10minutes. All samples were cross sectioned with grinder-polisher unit(Omnilap 2000 SBT Inc) after embeded in liquid unsaturated polyester (Epovia, Cray Valley Inc). RESULTS: There were the largest gaps in the neck areas of screws in hexagonal extension implants which were examined in this study. The leading edge of the abutment screw thread (superior surface) was in contact with the implant body thread, and the majority of the contacting surfaces were localized to the middle portion of the mating threads. Considerable variation in the contacting surfaces was noted in the samples evaluated. Amounts of contact in the abutment screw thread were larger for assemblies with Gold-Tite screw, gold alloy screw, Torq-Tite screw than those with titanium screws. The findings of intimate contact between the screw and screw seat were seen in all samples, regardless of manufacturers. However, microgap between the head and lateral neck surface of the screw and the abutment could be dectected in all samples. The findings of intimate contact between the platform of the implant and the bottom of the abutment were consistent in all samples, regardless of manufacturers. However, microgaps between the lateral surface of external hex of the fixture and the abutment could be dectected in all samples. CONCLUSION: Considerable variations in machining accuracy and consistency were noted in the samples and the implant-abutment-screw interfaces were incomplete. From the results of this study, further development of the system will be required, including improvements in pattern design.