Implant-supported overdenture is known as a useful appliance, instead of using the conventional complete denture, for better retention and stability. In this study 4 types of materials such as, gold bar/plastic clip(group AuP), gold bar/metal clip(group AuM), palladium bar/plastic clip(group PdP), and palladium bar/metal clip(group PdM) were used to evaluate the retention forces according to the type of clips and alloys used for bar fabrication, in the Hader bar system. Repeated insertions and removals of overdenture were conducted in each group, and the retention forces were measured and compared the data of each group according to the number of insertion and removal. The obtained results were as follows, 1. In the comparison of retention forces according to type of bar-clip, retention was increased in the order of group AuM, PdM, PdP, AuP, and the retention force of group AuM was significantly increased compared with those of others(p<0.05). 2. In the comparison of retention forces according to the number of insertion, only group PdP showed significant decrease in retention(p<0.05). 3. In the comparison of retention forces according to the type of bar and clip, there was no significant difference in the type of bar, but the retention of plastic clip was significantly higher than that of metal clip when Au bar was used(p<0.05). 4. In the observation of the bar surface, group AuM using Au bar and metal clip showed the most scratches among bar groups.
Alloys ; Denture, Complete ; Denture, Overlay* ; Palladium ; Plastics

PURPOSE: The purpose of this study was to evaluate the effects of the surface treatment and shape of the dental alloy on the composition of the prosthetic work and its metallic ion release in a corrosive medium after casting. MATERIALS AND METHODS: Orion Argos (Pd-Ag) and Orion Vesta (Pd-Cu) were used to cast two crowns and two disks. One of each was polished while the other was not. Two as-received alloys were also studied making a total of 5 specimens per alloy type. The specimens were submersed for 7 days in a lactic acid/sodium chloride solution (ISO standard 10271) and evaluated for surface structure characterization using SEM/EDAX. The solutions were quantitatively analysed for the presence of metal ions using ICP-MS and the results were statistically analysed with one-way ANOVA and a Tukey post-hoc test. RESULTS: Palladium is released from all specimens studied (range 0.06-7.08 microg.cm(-2).week(-1)), with the Pd-Cu alloy releasing the highest amounts. For both types of alloys, ion release of both disk and crown pairs were statistically different from the as-received alloy except for the Pd-Ag polished crown (P>.05). For both alloy type, disk-shaped pairs and unpolished specimens released the highest amounts of Pd ions (range 0.34-7.08 microg.cm(-2).week(-1)). Interestingly, in solutions submerged with cast alloys trace amounts of unexpected elements were measured. CONCLUSION: Shape and surface treatment influence ion release from dental alloys; polishing is a determinant factor. The release rate of cast and polished Pd alloys is between 0.06-0.69 microg.cm(-2).week(-1), which is close to or exceeding the EU Nickel Directive 94/27/EC compensated for the molecular mass of Pd (0.4 microg.cm(-2).week(-1)). The composition of the alloy does not represent the element release, therefore we recommend manufacturers to report element release after ISO standard corrosion tests beside the original composition.
Alloys ; Corrosion* ; Crowns ; Dental Alloys* ; Ions ; Nickel ; Palladium

The purpose of this study was to identifu the preventive and the preventive and the progressive inhibitory effects of enamel demineralization with fluoride releasing light-and self-cured orthodontic sealants(FluoroBond), in vitro, under the polarizing light microscope and the scanning electon microscope. The polarizing light microscopic group was subdivided into seven groups(Group A-Group G). The scanning electron microscopic group was also subdivided into seven groups(Group A'-Group G'). For polarzing light microscopic evaluation, longitudinal sections were made longitudinally by Maruto cutter(Maruto Co., Japan) and Maruto grinding machine(Maruto Co., Japan). Sections were examined and photographed by the polarizing light microscope(Olympus Optical Co., Japan) using crossed polars and with the enamel rod longitudinal axis oriented at 45degrees to the extinction position. For scanning electron microscopic evaluation, the specimens were coated with a highly conducting layer of gold palladium in a model Hus-4 high0vacuum evaporator* and examined in an ISI-100B scanning electron microcpe** operated at 20kV. The results of this study were as follows : 1. The mean deoths of artificial carious lesions under a polarized light microscope were Group A(5.08microgram), Group B(47.82microgram), Group C(8.42microgram), Group D(7.20microgram), Group E(85.41microgram), Group F(60.38microgram), Group G(60.13microgram). 2. There were statistically significant differences in Group B compared with Group A, C, and D(p<0.05), and also, in Group E compared with Group F and Group G(p<0.05). 3. Light-and self-cured orthodontic sealants had the preventive effects of enamel demineralization. 4. Light-and self-cured orthodontic sealants had the progressive inhibitory effects enamel demineralization. 5. The time progress of demineralizing agent no ingluecse on the samples of light-and self-cured orthodontic sealants under the scanning electron microscope. 6. There was no difference between the specimens of light-and self-cured orthodontic edalants both in the polarized light microscopic group and in the scanning electron microscopic group. *Hitachi Ltd, Tokyo, Japan **International Scientific Instruments, Santa Clara, Calif.
Axis, Cervical Vertebra ; Dental Enamel* ; Fluorides* ; Japan ; Palladium

PURPOSE: Candida albicans can cause mucosal disease in many vulnerable patients. Also they are associated with denture-related stomatitis. Electrolyzed water is generated by electric current passed via water using various metal electrodes and has antimicrobial activity. The aim of this study was to investigate antifungal activity of electrolyzed water on C. albicans biofilm. MATERIALS AND METHODS: C. albicans was cultured by sabouraud dextrose broth and F-12 nutrient medium in aerobic and 5% CO2 condition to form blastoconidia (yeast) and hyphae type, respectively. For formation of C. albicans biofilm, C. albicans was cultivated on rough surface 6-well plate by using F-12 nutrient medium in CO2 incubator for 48 hr. After electrolyzing tap water using various metal electrodes, the blastoconidia and hyphal type of C. albicans were treated with electrolyzed water. C. albicans formed blastoconidia and hyphae type when they were cultured by sabouraud dextrose broth and F-12 nutrient medium, respectively. RESULTS: The electrolyzed water using palladium electrode (EWP) exhibited antifungal effect on blastoconidia of C. albicans. Also, the EWP significantly has antifungal activity against C. albicans biofilm and hyphae. In the electrolyzed water using various metal electrodes, only the EWP have antifungal activity. CONCLUSION: The EWP may use a gargle solution and a soaking solution for prevention of oral candidiasis and denture-related stomatitis due to antifungal activity. (
Biofilms* ; Candida albicans* ; Candida* ; Candidiasis, Oral ; Electrodes ; Glucose ; Humans ; Hydrogen* ; Hyphae ; Incubators ; Palladium ; Stomatitis ; Water*

OBJECTIVEThe purpose of this study is to investigate the influence of cryogenic treatment and age-hardening heat treatment on the corrosion behavior of a dental casting Ag-Pd alloy.

METHODSA low gold content dental casting alloy composed of Ag-Pd-Cu-Au was prepared for this study. Corrosion test was performed according to ISO 10271:2001 dental metallie-corrosion test methods. Experimental specimens were casted according to a standard dental lost-wax casting procedure, treated with solution by heating the specimens to 900 degrees C, and immediately quenched in ice water. The specimens were then divided into four groups and subjected to heat treatment, cryogenic treatment, and heat treatment combined with cryogenic treatment. The specimens after the solution treatment were taken as control. The metallographic structures of the specimens were observed. The electrochemical parameters and the quantity of non-precious metallic ions released were evaluated via electrochemical and static immersion tests.

RESULTSMetallographic observation revealed that all the treatments resulted in a change in the microstructure of the alloy. The treatments were effective in improving the electrochemical parameters, such as an increase in Eocp and Ecorr and a decrease in Icorr (P < 0.05). The amount of non-noble metal ions released showed no difference compared with the control group (P > 0.05).

CONCLUSIONAfter different treatments, the antierosion properties of the alloy satisfied the ISO requirements. Age-hardening heat treatment and cryogenic treatment improved the corrosion resistance of the alloy.

OBJECTIVEThe purpose of this study was to investigate the influence of cryogenic treatment and age-hardening heat treatment on the micro-Vicker's hardness of palladium-silver dental alloys.

METHODSA low-gold content dental casting alloy composed of Ag-Pd-Cu-Au was prepared for this study. Experimental specimens according to standard requirements were prepared following a standard dental laboratory casting procedure, cast specimens were heated to 900 degrees C and quenched in ice water. The specimens were then divided into 4 groups. They were subsequently subjected to different treatments, including age-hardening heat treatment, cryogenic treatment, heat treatment combined with cryogenic treatment. The non-treated group was used as control. The micro-Vicker's hardness value was examined. The significance of correlation was analyzed.

RESULTSThe micro-Vicker's hardness of specimens after age-hardening heat treatment, cryogenic treatment, heat treatment combined with cryogenic treatment increased by 129%, 13% and 141%, respectively, compared with that of the non-treated control group. Conclusion Age-hardening heat treatment and cryogenic treatment were effective in elevating the hardness of Ag-Pd-Cu-Au alloy.

Melanosis ilei is an extremely rare condition in which black pigment, consisted of aluminum, magnesium, or silicon, accumulate in the terminal ileal mucosa. Medical treatment with charcoal enhances the neutralization of the toxic material and elimination of many drugs. In addition, it has been used as a traditional remedy in some oriental countries to relieve chronic diarrhea, abdominal pain, or acute enterocolitis, which is made up carbon, oxygen, aluminum, magnesium, silicon, calcium, and palladium. Two patients taking the charcoal for a long time underwent a colonoscopy to evaluate chronic diarrhea or abdominal pain. The colonoscopy revealed a normal colonic mucosa and multiple geographic black-pigmented mucosal changes at the terminal ileum. Therefore, it was assumed that melanosis ilei can develop in patients with long-standing charcoal ingestion. To the best of our knowledge, this is the first case of melanosis ilei associated with the ingestion of charcoal.
Abdominal Pain ; Aluminum ; Calcium ; Carbon ; Charcoal ; Colon ; Colonoscopy ; Diarrhea ; Eating ; Enterocolitis ; Humans ; Ileum ; Magnesium ; Melanosis ; Mucous Membrane ; Oxygen ; Palladium

BACKGROUND: We developed a new disposable anaerobic culture system, namely, the Quick anaero-system, for easy culturing of obligate anaerobes. METHODS: Our system consists of 3 components: 1) new disposable anaerobic gas pack, 2) disposable culture-envelope and sealer, and 3) reusable stainless plate rack with mesh containing 10 g of palladium catalyst pellets. To evaluate the efficiency of our system, we used 12 anaerobic bacteria. We prepared 2 sets of ten-fold serial dilutions of the 12 anaerobes, and inoculated these samples on Luria-Bertani (LB) broth and LB blood agar plate (LB-BAP) (BD Diagnostic Systems, USA). Each set was incubated in the Quick anaero-system (DAS Tech, Korea) and BBL GasPak jar with BD GasPak EZ Anaerobe Container System (BD Diagnostic Systems) at 35-37degrees C for 48 hr. The minimal inoculum size showing visible growth of 12 anaerobes when incubated in both the systems was compared. RESULTS: The minimal inoculum size showing visible growth for 2 out of the 12 anaerobes in the LB broth and 9 out of the 12 anaerobes on LB-BAP was lower for the Quick anaero-system than in the BD GasPak EZ Anaerobe Container System. The mean time (+/-SD) required to achieve absolute anaerobic conditions of the Quick anaero-system was 17 min and 56 sec (+/-3 min and 25 sec). CONCLUSIONS: The Quick anaero-system is a simple and effective method of culturing obligate anaerobes, and its performance is superior to that of the BD GasPak EZ Anaerobe Container System.
Bacteria, Anaerobic/*growth &development ; Bacteriological Techniques/instrumentation/methods ; Culture Media/chemistry ; Gases/chemistry ; Palladium/chemistry ; Reagent Kits, Diagnostic

Two isomers of nitrochlorobenzene (o-, and p-NCB) were treated by a Pd/Fe catalyst in aqueous solutions through catalytic amination and dechlorination. Nitrochlorobenzenes are rapidly converted to form chloroanilines (CAN) first through an amination process, and then rapidly dechlorinated to become aniline (AN) and Cl(-), without the involvement of any other intermediate reaction products. The amination and dechlorination reaction are believed to take place predominantly on the surface site of the Pd/Fe catalysts. The dechlorination rate of the reductive degradation of the two isomers of nitrochlorobenzene (o-, and p-NCB) in the presence of Pd/Fe as a catalyst was measured experimentally. In all cases, the reaction rate constants were found to increase with the decrease in the Gibbs free energy (correlation with the activation energy) of NCBs formation; the activation energy of each dechlorination reaction was measured to be 95.83 and 77.05 kJ/mol, respectively for o- and p-NCB. The results demonstrated that p-NCBs were reduced more easily than o-NCBs.
Catalysis ; Industrial Waste ; prevention & control ; Iron ; chemistry ; Isomerism ; Kinetics ; Metals ; chemistry ; Nitrobenzenes ; chemistry ; Palladium ; chemistry ; Structure-Activity Relationship ; Waste Disposal, Fluid ; methods ; Water ; chemistry ; Water Purification ; methods

OBJECTIVE: To study the effect of various intracanal materials on the accuracy of oral maxillofacial cone-beam computed tomography (CBCT) for the diagnosis of vertical root fracture (VRF). METHODS: A total of twenty-four structurally intact single root canal dried and isolated teeth extracted for orthodontic treatment or periodontal disease were collected. The teeth were decrowned along the cemento-enamel junction (CEJ) and then used as samples for the study after conventional root canal preparation and post preparation. The 24 samples were divided into two groups with 12 samples in each group. Group A was the control group (no VRF group). According to intracanal materials, they were divided into five subgroups: blank group, fiber post group, gutta-percha point group, titanium post group and gold-palladium post group. Group B was the experimental group (VRF group), and subgroups were grouped as above. The VRF model was prepared by a unified method in the VRF group: the root was completely fractured in the buccolingual direction with a custom root canal nail and then cemented and reset. The control group was not subjected to the simulation of VRF. Titanium post and gold-palladium post were made according to the individuality of the root canal preparation, and the tightness of the post to the root canal wall was confirmed by X-ray radiograph. Then all the samples were scanned by CBCT in the isolate swine mandibular alveolar sockets. The diagnostic accuracy was statistically analyzed via blind interpretation by experienced endodontic specialists and oral and maxillofacial medical imaging specialists. RESULTS: The accuracy of the diagnosis of VRF in the blank group, fiber post group, gutta-percha point group, titanium post group, and gold-palladium post group in CBCT was 95.83%, 91.67%, 87.50%, 79.17%, and 45.83%, respectively. Compared with the blank group, the differences were not statistically significant in the fiber post group (P>0.999), the gutta-percha point group (P=0.500) and the titanium post group (P=0.125). The lowest diagnostic accuracy of VRF was found in the gold-palladium post group, and the difference was statistically significant compared with all other groups (P < 0.001). CONCLUSION Various intracanal materials have different degrees of influence on the diagnostic accuracy of VRF diagnosis in CBCT. The influence of fiber post, gutta-percha point and titanium post was small, while the influence of gold-palladium post was significant.
Animals ; Cone-Beam Computed Tomography/methods* ; Gold ; Gutta-Percha ; Palladium ; Swine ; Titanium ; Tooth Fractures/diagnostic imaging* ; Tooth Root/injuries* ; Reproducibility of Results