[What the technician should be careful of in preparation of full porcelain artificial teeth].
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Color↗
Biomedical subjects
H Schwickerath
Publications and source records attributed to H Schwickerath.
[Nickel solubility of dental alloys in the immersions-test and in the mouth].
The nickel solubility of 7 different nickel-alloys was tested in vivo and in vitro. The results revealed that the solubility of the alloys, after encasing them in lactic-acid solution of pH 4.2 for a period of seven days, allows to find out those alloys, which will also clinically dissolve small amounts of ions only. The Ni59-65Cr26-23Mo11-9 mass per cent alloys dissolved the smallest quantities of nickel in the in vitro and the in vivo tests and are therefore recommended for clinical use instead of the type Ni74-85Cr15-13Mo5-3 alloys.
Chromium Alloys↗
[Mechanical strength of ceramic materials for fusing on titanium restorations].
Bending, splitting tensile, and bond strengths of four ceramic systems for veneering titanium frameworks as well as the fatigue strength of the complete metal-ceramic crown were evaluated. The mechanical properties of ceramo-metallic systems are comparable with those of conventional dental ceramics. A slight increase in bending, tensile, and bond strengths when using higher firing temperatures was observed, although this did not result in an increased endurance strength of the complete system.
Crowns↗
[Nickel release of dental alloys as a function of the pH value of the corrosive solution].
Ni-59-65Cr26-23Mo11-9 alloys released distinctly lower quantities of nickel in lactic acid/saline solutions at pH 2.3, 4.2, or 6.5 than type Ni66-85Cr15-13Mo7-0 alloys for a period of 1 day and, subsequently, periods of 3 days over a total period of 33 days. While nickel solubility was similarly high at pH 2.3 and 4.2 (varying between 0.1 microns/cm2 d and 222 microns/cm2 d depending on the type of alloy), a maximum of 2 microns/cm2 d of nickel dissolved from all tested alloys at a pH value of 6.5.
Chromium Alloys↗
[Bond between wash elastomers and putty silicones].
Areas of elastomeric impression materials are deformed when impressions are removed from undercuts in the mouth. Bond strength between low and high viscosity impression materials is considered to be higher than the adhesion between impression material and teeth or gum (up to 50 N/cm2). Otherwise failure of impression may be due to failure of the bond between putty and wash elastomers. Bond strength of condensation putty and wash silicones was evaluated at about 70 N/cm2. Bond of putty and addition-cured wash silicones failed at about 130 N/cm2. Bond strength decreased to 34 N/cm2, when putty material was contaminated with saliva and dried before adding the wash elastomer. When putty silicones were rinsed and dried after contamination with saliva bond strength increased up to 80-90% that of fresh probes.
Adhesiveness↗
[Tensile strength of dental porcelains].
Flexural, compressive and tensile strength as well as the modulus of elasticity of 15 different dental ceramics were evaluated. Conventional dental ceramics differed insignificantly in their mechanical properties. By testing new products like Cerec 2 and especially In-Ceram there was found an evident increase in inner strength. For comparison the strength of some other new ceramics as Dicor increased slightly related to conventional ceramics.
Aluminum Oxide↗
[Nickel solubility and metallic taste].
Main causes for metal taste may be deficiency diseases (especially deficiency of zinc), medication or dental restorations. Saliva of probationers with partial dentures was analyzed for their nickel contents. The solubility behavior in saliva of the alloys studied was related to metal taste and burning sensation. For most alloys the frequency of metal taste was in accordance with the nickel solubility in saliva.
Adult↗
[On the introduction of new materials and procedures].
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Crowns↗
[Injury-free removal of cemented crowns and bridges].
Seven methods for removing crowns and bridges were studied in in vitro tests. Systems gripping the crowns on both sides led to the best results. Cemented crowns were loosened by ultrasound. All restorations could be removed after an average time of 6 1/2 min ultrasound influence. The increase of temperature in the pulp chamber requires sufficient waterspraying.
Crowns↗
[Corrosion resistance and bond strength of dental alloys].
Investigated Ni-alloys, which showed extensive solubility of Ni particles in corrosion bathes due to DIN 13927, also revealed pronounced lost of bond strength to ceramic veneers when immersed into corrosion bathes of equal constitution. Noble metal alloys with a gold concentration more than 50 percent, however, showed no such large lost of bond strength. Pd alloys showed a lost of bond strength which increased with their Ga concentration. Co alloys revealed a behavior similar to the Ni alloys but with no obvious correlation between solubility and lost of bond strength.
Corrosion↗
[Testing the solubility of dental alloys].
Solubility of dental non-precious alloys was investigated. In the first few days of immersion high concentrations of dissolved metal ions were observed. For some alloys the rates increased, for others they decreased with time, when the immersion bath was replaced by a freshly prepared one. Solubility increased slightly when metal surfaces were ground with emery-paper, grain size 1200, which was intended to simulate the disturbance of the passivation layer by mastication. Porcelain firing, however, caused largely increased rates, depending on the kind of alloy. The results are to be taken into consideration when formulating standards for corrosion resistance tests.
Corrosion↗
[Solubility of nickel from dental alloys in saliva].
Dental students in the clinical courses of prosthodontics manufactured maxillary cast partial dentures from 6 nickel-containing alloys according to set guidelines. Prior to insertion as well as up to 7 days after insertion resting saliva samples were collected and analyzed for their nickel contents with the aid of atomic absorption spectrometry (AAS) using a graphite tube. 20 min after insertion the salivary nickel levels were above the blank value. After 3 h the salivary nickel levels were as half as high compared to values of 20 min. After 7 days for most alloys they decreased to the starting values again.
Dental Alloys↗
[Properties and behavior of palladium and non-precious metal alloys that can be fired].
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Corrosion↗
[Solubility of dental alloys in saliva].
Five dental probationers each of the clinical courses for prosthodontics manufactured maxillary cast partial dentures from 7 nickel-bearing alloys according to given guidelines. Prior to insertion as well as after 20 min, and in some cases 3 h, resting secretion saliva samples were collected and analyzed for their nickel contents with the aid of atomic absorption spectrometry (AAS) using a graphite tube. Further saliva samples were collected following the insertion of plates inactivated in lactic acid and saline, and after intensive polishing and reinsertion. 20 min after insertion the salivary nickel levels were above the blank value. After 3 h they decreased to the blank value again. The solubility behavior in saliva of the alloys studied was in accordance with the results obtained in corrosion tests in vitro.
Dental Alloys↗
[Compressive strength of metal-ceramic occlusal veneers].
Ceramometallic specimens, circular in section, of varying thickness and manufactured by means of different procedures, have been tested to destruction of the ceramic layer under a once-through continuously increasing force at defined points. Identical specimens were used to determine the number of load cycles under increasing continuous stress of 430 N until the ceramic layer failed. The fatigue strength increased with the thickness of the metallic layer and was further increased by a high inherent strength of the ceramic layer. In restorations with only a thin metallic layer (foil crowns) and/or low strength values of the metal (electroplated ceramic crowns) an overall thickness of the layers of more than 1.5 mm is recommended in the occlusal area to avoid premature failure.
Bite Force↗
[Estimation of usefulness of metal-ceramic restorations].
Many factors are responsible for the quality and the usefulness of the denture: form and dimension of the construction, the distribution of the compound materials in the size, the strength of the compound and the particular materials and their plastic-elastic behaviour, the impact of different manufacturing processes. The paper describes how these factors are influencing one another and presents and discuss testing methods for sampling comparable results. Instructions will be given to the examination of the application of new methods (Ceraplatin*-crown, ceramical faced galvanic crown, metal saving crown and bridge constructions).
Crowns↗
[Lightweight construction--sense and nonsense].
Lightweight construction techniques make sense as long as certain basic principles are observed. This requirement is best met by the shell construction technique. Lightweight constructions using the ultralite foil technique have considerable shortcomings, and it is only in rare cases that they may be used on a long-term basis. The assessment of the expected chewing forces as well as the shape and dimension of the bridge, limited by the given clinical conditions of the case, are the factors governing the decision for a specific framework construction. The design of the interproximal spaces requires particular attention. The most economical solution is a durable construction involving low material and production costs.
Denture Design↗
First experiences with resin-bonded bridges and splints--a cross-sectional retrospective study, Part II.
This second report establishes that the success of treatment with resin-bonded bridges was dependent upon many factors. Factors controlled by the clinician, such as case selection and treatment planning greatly influence the clinical success. It was possible to show that framework preparation and the amount of available enamel were significant factors, whereas isolation technique, type of retention mechanism and type of adhesive used were of less importance. Longitudinal studies are needed to confirm these observations. Seventeen clinicians placed 496 resin-bonded bridges and splints with different retention mechanisms and bonding agents. These reconstructions were examined in regard to the failure rate and in regard to reattachment problems. Ninety-seven per cent of the bridges and 90% of the splints were still in place after 1 year. For bridges and splints a 90% success rate was ascertained after 2 years.
Adhesives↗