ABSTRACT
Aim: The aim of this in vitro study was to evaluate the flexural bond strength of porcelain to combinations of used and new nickel-chromium alloy in various proportions. Materials and Methods: Used and new nickel-chromium bonding alloys were combined in various proportions (groups I to V; 10 samples per group) and their flexural bond strengths with porcelain were compared. A three-point loading system was used for the application of load. Load was applied at a constant speed of 0.5 mm/minute and the load required to fracture the porcelain was recorded for each specimen. Statistical Analysis Used: (a) Analysis of variance (ANOVA) and (b) Duncan's multiple range tests. Results: The best bond strength values were seen when 100% new alloy was used. According to the findings of this study, there was no adverse effects noted with up to 75% recast metal, but serious changes were found in the bond strength values when 100% old metal was used. Conclusions: The following conclusions were drawn from the study Fresh nickel-chromium alloy shows the greatest porcelain adherence. There is no significant change in bond strength of ceramic to alloy with up to 75% of used nickel-chromium alloy. At least 25%- of new alloy should be added when recycled nickel-chromium alloy is being used for metal ceramic restorations.
Subject(s)
Adhesiveness , Aluminum Silicates/chemistry , Chromium Alloys/chemistry , Dental Bonding , Dental Casting Technique , Dental Impression Materials/chemistry , Dental Porcelain/chemistry , Dental Stress Analysis/instrumentation , Equipment Reuse , Humans , Materials Testing , Methylmethacrylates/chemistry , Pliability , Potassium Compounds/chemistry , Stress, MechanicalABSTRACT
Objective To compare advantages and disadvantages of ceramic crown and porcelain fused to metal(PFM),provide better rehabilitation ways for patients.Methods 258 porcelains were,divided into two groups:ceramic crown group 98 and metal ceramic crowns group 160,for preparation of abutment,modulus,colorimetric,feed production.Results Follow-up observation for 2 years,the 15 crowns of all appeared the gingival edge coloring with different degree,are PFM,10 patients were not satisfied with the color of restorations.8 repair body porcelain.Conclusion Inner crown metal of PFM is thin and light,with high hardness and compressive strength.It rarely occur deformation since repeated the barbecue at high temperatures,so suitable for large span bridge restoration.Ceramic crown because of no metal structure,good light transmission and light reflecting function,can reproduce the natural teeth translucent depth and color depth,strong sense of hierarchy,suitable for the repair of anterior teeth.
ABSTRACT
PURPOSE: The purpose of this study was to evaluate the level of electro-chemical corrosion and surface roughness change for the cases of Ti abutment connected to restoration made of base metal alloys. MATERIALS AND METHODS: It was hypothesized that Ni-Cr alloys in different compositions possess different corrosion resistances, and thus the specimens (13x13x1.5 mm) in this study were fabricated with 3 different types of metal alloys, commonly used for metal ceramic restorations. The electrochemical characteristics were evaluated with potentiostat (Parstat 2273A) and the level of surface roughness change was observed with surface roughness tester. Paired t-test was used to compare mean average surface roughness (Ra) changes of each specimen group. RESULTS: All specimens made of nickel-chromium based alloys, average surface roughness was increased significantly (P < .05). Among them, the Ni-Cr-Be alloy (0.016 +/- 0.007 microm) had the largest change of roughness followed by Ni-Cr (0.012 +/- 0.003 microm) and Ni-Cr-Ti (0.012 +/- 0.002 microm) alloy. There was no significant changes in surface roughness between each metal alloys after corrosion. CONCLUSION: In the case of galvanic couples of Ti in contact with all specimens made of nickel-chromium based alloys, average surface roughness was increased.
Subject(s)
Alloys , Chromium Alloys , Corrosion , Family Characteristics , Metal Ceramic Alloys , TitaniumABSTRACT
Objective: To compare the influence of nickel-chromium alloy and gold-platinum alloy porcelain-fused-to-metal ( PFM ) on ultramicrostructure of canine gingival tissues, to survey the biological effects after PFM full crown restoration, and to provide data for selection of PFM materials. Methods; The nickel-chromium alloy and gold-platinum alloy PFM full crowns were used to repair canines in 3 healthy dogs. The microstructure of canine gingival tissue was observed through light microscope and transmission electron microscope. Apoptosis of canine gingival cells was detected by TUNEL method. Results; Under light microscope, inflammatory cell infiltration and partial bleeding were seen in the nickel-chromium alloy PFM full crown repaired canine gingival tissues. Under transmission electron microscope, large amount of cell apoptosis and neuclear condensation were observed in these tissues,and apoptotic index was 58.63% ±11. 12%. While under light microscope, inflammatory cell infiltration and partial bleeding were not seen in the gold-platinum metal PFM full crown repaired canine gingival tissues. Under transmission electron microscope, only small amount of cell apoptosis was detected in these tissues,and apoptotic index was 26. 90% ± 17. 35%. Statistical significance was found in both nickel-chromium alloy group and gold-platinum metal group compared to control group. There was also statistical significance between nickel-chromium alloy group and gold-platinum metal group in cell apoptosis numbers (P <0. 05). Cell apoptosis number in nickel-chromium alloy group was much higher than that in gold-platinum metal group. Conclusion; The negtive effects on ultramicrostructure of gingival tissue using nickel-chromium alloy PFM are more evident than using gold-platinum metal. When select PFM to repair defect teeth, it is better to select the inactive gold-platinum metal PFM as base crown.
ABSTRACT
This study was conducted to evaluate the tensile bond strength by bonding the dental bracket with Super-bond after treating the surface of dental Nickel-Chromium alloy with sandblasting, sandblasting & tin-plating, respectively, and tin-plating. 10 pieces of Nickel-Chromium alloys with brackets bonded with Super-bond without their surface treatment were sampled as a control group, 20 pieces of Nickel-Chromium alloy brackets bonded with Super-bond after treating them with sandblasting as group I, 20 pieces of Nickel-Chromium alloys tin-plated and bonded with Super-bond after sandblasting as group II, and then 20 pieces of alloys with brackets bonded with Super-bond after tin-plating as group III. The result of those examination and comparison is summarized as follows: 1. Group I showed the mean tensile bond strength of 14.41+/-2.24MPa which was highest among 4 groups, followed by group III( 13.59+/-L51MPa ), group II( 12.27+/-1.45MPa ), and control group( 10.50+/-1.57MPa ), respectively. However, it was shown that them was no statistically significant difference between group I and III, group III and II, and group II and control group( P>005 ). 2. The main failure pattern of those brackets showed that 70% of the control group had an adhesive failure at the bracket Superbond interface, and 30% at the Nickel-Chromium alloy-Superbond interface, while other groups did the adhesive failure at the bracket-Superbond interface. 3. When examined under SEM, it was shown that adhesives were mostly attached to the surface of the Nickel-Chromium alloy for all groups while a considerable quantity of adhesives were attached to the bracket base. Then, those samples treated only with sandblasting showed the most even and remarkable roughness of their surface.