A method has been developed for the consistent adherence of flame-sprayed ceramic coatings to Vitallium. The critical step involves etching the metal by the anodic polarization technique. This procedure allows complex geometrics to be corroded evenly, and, by suitable choice of etching solution and conditions, enables any metal to be substituted. The bond is capable of sustaining more severe deflections than are experienced during intraoral function. Despite the number of cracks generated during testing, the ceramic layer remains intact. The ceramic-metal bond is mechanical. The corroded surface provides greater surface area, thus permitting a number of retention sites. Analysis of the ceramic microstructure finds it to be suitable for tissue ingrowth.

Ceramics↗

PubMedDate not supplied

Mechanical properties of a nonprecious type III alloy.

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Chromium↗

PubMedDate not supplied

Selection of a resin system for anterior fracture treatment.

The tensile strength of the bond formed between etched bovine enamel and selected resin systems was evaluated; also, the need for a resin pulpal barrier was examined. Results indicate that the BIS-GMA unfilled primer is unnecessary for strength or as a pulpal protectant. The large scatter of results substantiates the clinical hypothesis that the effectiveness of the acid etch is highly variable.

Acrylic Resins↗

PubMedDate not supplied

Incisal-edge strength of porcelain laminate veneers restoring mandibular incisors.

Porcelain laminate veneers can be used to increase incisal-edge length. The purpose of this study was to determine the fracture resistance of porcelain veneer restorations on Cymel 1077 mandibular incisors that were incisally reduced 0.0, 0.5, 1.0, and 2.0 mm. Variables studied were incisal-edge length and the angle of applied force. Sixty-one porcelain laminate veneers were made to restore incisal-edge length and bonded to the prepared teeth. Samples were fractured at force angles of 130 degrees and 137 degrees. No significant difference was found between varying incisal-edge lengths (P > .05). However, the lower applied angle required greater average force to fracture (P = .005) as tested by ANOVA.

Analysis of Variance↗

PubMedDate not supplied

Laser fusion of selected dental casting alloys.

Laser-fused precious, nonprecious, and mixed metal welds were investigated for optimum weld energy requirement as determined by tensile strength tests. These strengths were compared to soldered unions. Laser fusion is as good as, or better than, unions created by conventional dental joining methods.

Analysis of Variance↗

PubMedDate not supplied

Mechanical property and microstructural variations for recast low-gold alloy.

Using polystyrene plastic patterns meeting the dimensional requirements of ANSI/ADA specification no. 5, tension test specimens were recast multiple times from a popular Type III gold (46%) alloy. The alloy was melted by electrical heating in a graphite crucible and four conditions were compared: new alloy and alloy cast two, three, and four times (n = 4). After casting, age-hardened specimens were loaded at an elongation rate of 0.5 mm/min until failure, and the stress-strain plots were recorded. Values of yield strength, tensile strength, and percentage elongation for the specimen groups were analyzed by one-way analysis of variance, followed by the Student-Newman-Keuls multiple range test. Significant decreases (P < .01) in yield strength and percentage elongation occurred with recasting, although there were no significant differences (P > .05) in tensile strength. Scanning electron microscope examination revealed that the number of casting defects increased with remelting, and that their presence dominates the tensile fracture process. The variation in mechanical properties of the alloy with remelting was attributed to these casting defects.

Analysis of Variance↗

PubMedDate not supplied

Irreversible hydrocolloid and gypsum interactions.

This study examined the compatibility of nine popular gypsum products with three more recently developed irreversible hydrocolloid impression materials, some of which were disinfected before pouring. A test die and evaluation procedure conforming to ANSI/ADA specification no. 18 standards were used to evaluate detail reproduction of the impression materials and detail transfer and roughness of the resultant die. Statistical evaluation of the data revealed that there continue to be deleterious surface interactions between specific irreversible hydrocolloid materials and gypsum products. Analysis also confirmed that the phenolic disinfectant used in this study did not influence the surface interaction between materials nor alter the resultant dimensional properties of the gypsums used.

Alginates↗