ABSTRACT
The authors evaluated, in vitro, the effects of etching glass ionomer cements prior to the application of a bonding agent and a resin composite on the bond strength of the glass ionomer/resin composite interface. Six glass ionomer cements were tested using the same bonding agent/resin composite system (Scotchbond Multipurpose/Z 100). For each material, 16 specimens were prepared and divided into two groups. Eight of the specimens were not etched while eight were etched with 37% phosphoric acid for 15 seconds. All the materials were used according to the manufacturers' instructions. Glass ionomer cylinders were prepared and were mounted in an assembly apparatus and the bonding agent/resin composite transferred to a demarcated area on the cement surface. The specimens were stored for 24 hours in distilled water at 37 degrees C and thermocycled. After thermocycling, the specimens were placed in a testing machine and a shear load applied with a knife-edged rod at the glass ionomer/resin composite interface. The shear bond strength was calculated and expressed in MPa. Data were analyzed by ANOVA and the Tukey-Kramer test. There were no significant differences among the shear bond strengths of the resin composite to etched and non-etched glass ionomer cements.
Subject(s)
Acid Etching, Dental , Composite Resins/chemistry , Glass Ionomer Cements/chemistry , Acid Etching, Dental/statistics & numerical data , Analysis of Variance , Materials Testing/methods , Materials Testing/statistics & numerical data , Random Allocation , Tensile StrengthABSTRACT
Thirty single-rooted teeth were prepared to receive cast posts. After cementation of the post the teeth were divided into three groups. Group I did not receive any treatment, whereas the posts in groups II and III were treated with an ultrasonic device, for 2 min and 5 min, respectively. The force required for post removal was determined using a universal test machine. No statistical differences (P > 0.05) were found between the groups where ultrasound had been used. Significantly reduced forces were necessary to remove the posts from group II and III, compared with group I which did not receive ultrasonic treatment (P < 0.05).
Subject(s)
Dental Debonding/methods , Post and Core Technique/instrumentation , Root Canal Therapy/methods , Ultrasonics , Analysis of Variance , Humans , Random Allocation , ReoperationABSTRACT
Thirty single-rooted teeth were prepared to receive cast posts. After cementation of the post the teeth were divided into three groups. Group I did not receive any treatment, whereas the posts in groups II and III were treated with an ultrasonic device, for 2 min and 5 min, respectively. The force required for post removal was determined using a universal test machine. No statistical differences (P > 0.05) were found between the groups where ultrasound had been used. Significantly reduced forces were necessary to remove the posts from group II and III, compared with group I which did not receive ultrasonic treatment (P < 0.05).
Subject(s)
Dental Debonding/instrumentation , Post and Core Technique/instrumentation , Ultrasonics , Analysis of Variance , Humans , Reoperation , Root Canal TherapyABSTRACT
The tensile bond strengths of five retention techniques for bonded cast restorations were tested. The retentive methods were the electrolytic etch, Rochette's perforations, retention beads, the recessed surface, and soldered orthodontic mesh. The electrolytic etch and recessed surface methods gave the highest values of bond strength, followed by retention beads. Rochette's perforations and the soldered orthodontic mesh failed to surpass the bond strength of the control group (no additional retention) after 1 hour and provided the lowest bond strength after 24 hours.
Subject(s)
Denture Design , Denture Retention , Denture, Partial, Fixed, Resin-Bonded , Acid Etching, Dental , Acrylic Resins/chemistry , Chromium Alloys/chemistry , Composite Resins/chemistry , Dental Bonding , Dental Soldering , Electrolysis , Materials Testing , Nitrates , Nitric Acid , Surface Properties , Tensile StrengthABSTRACT
This article characterizes the structural phases present in the copper-based metallic alloy system "Cu-Zn-Al-Ni" developed for dental use, and relates those phases to other properties. The characterization was obtained after casting (using the lost wax process), and after heat treatment. In order to obtain better corrosion resistance by changing the microstructure, the castings were submitted to 30, 45 and 60 minutes of heat treatment at the following temperatures: 750 degrees C, 800 degrees C, and 850 degrees C. The various phases were analyzed using X-ray diffraction and scanning electron microscopy (SEM). The results after heat treatment showed a phase (probably Cu3Al), that could be responsible for the improvement in the alloy's resistance to corrosion as compared to the as-cast structure.
Subject(s)
Copper/chemistry , Dental Alloys/chemistry , Dental Casting Technique , Aluminum , Corrosion , Hot Temperature , Microscopy, Electron, Scanning , Nickel , Waxes , X-Ray Diffraction , ZincABSTRACT
A new bleaching technique for pulpless teeth is demonstrated by a clinical case. The principle of the method is to clean the dentinal tubules by an 1% sodium hypochlorite solution activated by a 40 endosonofile. A mixture of sodium perborate and a 3% hydrogen peroxide is left in the pulp chamber between the treatment sessions.
Subject(s)
Tooth Bleaching/methods , Ultrasonic Therapy , Adult , Borates , Humans , Hydrogen Peroxide , Male , PulpectomySubject(s)
Acrylic Resins , Cementation/methods , Crowns , Denture, Partial, Temporary , Gold Alloys , Dental Bonding , Dental Cements , Humans , Surface Properties , Tensile StrengthABSTRACT
In the study, cast gold crowns were cemented similar to methods used for patients. Conclusions were that: 1. Fresh cement painted with a camel brush in the part of the crown to be cemented promotes a better fit than when the crown is completely filled with cement. 2. Mechanical vibration of the crown at cementation promotes a better fit. 3. Venting the crown, an internal relief by acid etching, or a combination of both these procedures improve the seating of the crown during cementation. 4. The association of one or numerous variables used in this study considerably improves the fit of the cemented crown.
Subject(s)
Cementation , Crowns , Acid Etching, Dental , Surface Properties , Vibration , Zinc Phosphate Cement/administration & dosageABSTRACT
Vibration, applied at the beginning of cementation, improves the fit of MOD inlays and cast complete crowns when they are compared to the same castings cemented without vibration. The Medart pressure applicator produced better adaptation. Orange wood blocks and Burlew disks produced similar results. They were less efficient than the Medart pressure applicator. Cotton rolls resulted in the highest fit discrepancy.
Subject(s)
Cementation/methods , Crowns , Inlays , Pressure , Vibration , Dental Bonding , Models, Anatomic , Rheology , Surface Properties , Zinc Phosphate CementABSTRACT
An in vivo study was developed to observe the penetration of 131INa around the margins of complete crown castings cemented with zinc phosphate cement with and without the application of different protective agents, with the following results. 1. Complete crowns cemented with zinc phosphate cement showed 131INa marginal leakage differences depending on the protective material used prior to cementation. 2. The best protective agent against marginal leakage according to this study was two layers of cavity varnish applied to the margins. 3. The amount of marginal leakage can be influenced by crown adaptation and the film thickness of the cement. 4. There were no differences between test periods of 1 hour or 21 days after cementation.
Subject(s)
Crowns , Dental Cavity Lining , Zinc Phosphate Cement , Anti-Infective Agents , Calcium Hydroxide , Cementation , Dental Bonding , Humans , Surface PropertiesABSTRACT
No type of pin inclusion investigated in this study produced consistent increases or decreases in the strength of amalgam specimens under a variety of loading conditions and specimen ages. However, comparison of relative values for specimens tested under the same conditions showed that the highest fracture loads were found more often for specimens containing threaded gold pins than for any other type of specimen.