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Tear and energy properties of three impression materials.

A dental impression material must have sufficient strength to allow removal from a gingival sulcus without tearing; it must also have adequate elastic recovery. This study examined the tear energy, the permanent deformation upon extension, the energy absorbed to an estimated point of significant deformation, and the extent of permanent deformation at tear of polysulfide, polyether, and addition-reaction silicone impression materials. As expected, polysulfide material had a higher tear energy and strain at tear than either polyether or addition-reaction silicone materials. However, the more relevant clinical properties, such as energy absorbed per amount of deformation and tear at a point of minimal permanent deformation, favored the addition-reaction silicone material, followed by the polyether material.

Analysis of Variance↗
PubMed1989

[Problems in disinfection of dental impression materials].

In view of the risk of infection of the dentist and his staff in the dental surgery and dental laboratory and also of the patient with regard to hepatitis B and potentially also of AIDS, interruption of possible chains of infection by means of specific disinfection measures is to be demanded. Whereas appropriate hygiene concepts exist for disinfection of instruments, surfaces of equipment and furniture with regard to selection and application of various methods which may be considered, there are still extensive deficits for the domain of impression materials and their possible decontamination. In this regard, dentists frequently lack information with an adequate scientific basis that is understandable and oriented to practical requirements. Owing to the diversity of materials and their different behavior (cf. Tab. 1), appropriate recommendations can only be made on the basis of extensive studies. We assume that a practically relevant procedure must meet the following requirements: 1) sufficiently high rates of bacterial reduction in accordance with the guidelines of the DGHM, 2) lack of alterations in the dimensions or surfaces of the materials, 3) universal applicability, 4) practicability within a time period which is acceptable for smooth operation of the practice, 5) can be employed without problems for the staff. The object of the report are bacteriological results and materials testing data for the application of various methods of disinfection to selected impression materials. To summarize, it can be stated with regard to the bacteriological results that disinfection of impression materials is possible with fulfillment of the criteria specified above, but that there is a pronounced dependence of the results on the product formulation of the disinfectant and also of the impression material (cf. Fig. 4 and 5). Investigations of the material-related effects of the disinfection measures showed that extrapolation of the findings from one group of materials to another is also not possible in this connection, and that moreover the materials used to produce the model must also be included besides the impression materials used (cf. Fig. 9). Accordingly, statements on the suitability of a disinfection procedure are present admissible at most for the respective combination of materials tested, which makes practical introduction problematical.

Bacteria↗
PubMed1989

[Profilometric studies on the surface reproduction of dental impression materials].

The reproduction of elastic impression materials is described with a laser-technique. This technique allows a quantitative evaluation without touching and deforming the surfaces. Although it is possible to measure differences, clinically relevant differences between several elastomere and one hydrocolloid material are not found.

Dental Impression Materials↗
PubMed1976

A new method of recording the elastic recovery of dental impression materials.

Assessments of the elastic recovery of elastic impression materials have so far been carried out only to a limited degree because of lack of adequate measuring instruments. A method is described which enables measurement and recording electronically of the creep properties, including the elastic recovery time and the permanent deformation, of elastic impression materials in relation to their degree of setting and to the size and time of the induced deformation. The apparatus and the experimental and mathematical methods described can easily be handled by a reasonably skillful laboratory assistant.

Dental Impression Materials↗
PubMed1998

Antimicrobial activities of dental impression materials.

OBJECTIVE: The aim of this study was to measure the in vitro killing effects five commercial alginate impression materials had on five test microorganisms. METHODS: Two alginates with no added disinfectant, one supplemented with chlorhexidine and two others containing quaternary ammonium compounds were tested. Challenge microbes included two gram-positive cocci, two gram-negative bacilli and a yeast. Saline solutions containing standardized concentrations of test microbes were used to mix the alginates. Some set specimens were immediately homogenized and the resulting fluids diluted and spread plated. Other specimens were processed 30 or 60 min after setting. After culturing, the numbers of colonies were counted and the levels of microbial reductions determined. RESULTS: Unsupplemented alginates had no antimicrobial effects. The quaternary-ammonium-containing alginates were completely effective against all five test microorganisms. The alginate with chlorhexidine killed all the gram-negative bacilli and the majority (95-99%) of the gram-positive cocci and yeast. SIGNIFICANCE: Results indicated that disinfectant-containing alginate impression materials could reduce the number of soiling microorganisms present on and within test specimens.

Alginates↗
PubMed1977

[Contact allergy caused by new dental impression materials].

In 1965 a new group of polymeric materials has been introduced into dentistry which is used for temporary crowns, bridges and impression materials. In handling it contact may occur with all components of these impression materials (Scutan, Impregum). Contact over a long period may lead to allergic contact dermatitis. Epicutaneous tests in three dentists and a technical assistant revealed that the catalysts of the impression materials are responsible for contact allergy. In experiments with guinea pigs the strong sensitization capacity of the catalysts could be demonstrated. Methyl-dichlorbenzolsulfonat (catalyst of Impregum) showed a stronger effect than methyl-p-toluolsulfonat (catalyst of Scutan). Besides their allergenic properties these substances also act as primary irritants. As these materials are widespread in dentistry more attention should be payed at the risk of hand eczemas in dentists and dental personnel caused by the catalysts of Impregum and Scutan.

Adult↗
PubMed1984

Tear and rupture of elastomeric dental impression materials.

The curing time dependence of the tear energy, tensile strength and ultimate extension ratio of a range of characterized elastomeric impression materials was investigated. This variation of tensile strength and ultimate extension ratio was correlated with the development of the network structure. The tear energy showed only minor changes as the curing proceeded.

Dental Impression Materials↗
PubMed1975

Reactions to dental impression materials.

In the department of prostheitc dentistry at Groningen, during the past four years, approximately 2,000 persons have been treated with Scutan, and epimine plastic for temporary crowns and bridges and Impregum, a polyether impression material. A total of ten patients complained of untoward reactions. Patch tests with the basic materials were performed on four of them. Positive allergic reactions were obtained to patch tests with the catalyst methyl p. toluene sulfonate 0.1% in dibenzyltoluol present in Scutan, and the catalyst methyldichlorobenzene sulfonate 0.1% in dibenzyltoluol present in Impregum. Four control subjects did not react to these concentrations.

Adult↗
PubMed1995

[Right-sided recurrent retention pneumonia of changing localization after aspiration of dental impression material with almost complete casting of a segmental bronchus in a previously healthy woman].

Aspiration of foreign bodies is extremely rare in adults but frequent in children. Foreign bodies aspired by adults are usually immediately identified and quickly removed. This, however, was not the case with the patient under report. In a women patient of 51 years of age who had so far been completely healthy, a certainly rare endobronchial foreign body remained unidentified for eighty-six days. Even in adults one must take the possibility of foreign body aspiration into consideration whenever signs are seen such as dyspnoea, recurrent pneumonias, unproductive coughing, retrosternal pain, distant cardiac murmur if no obstructive disturbance of ventilation had already existed before, and especially if there are obstructive respiratory sounds of laterally different amplitude.

Bronchography↗
PubMed1986

Alginate dental impression materials: chemistry, structure, and properties.

The setting behavior of calcium alginate impression materials was investigated by monitoring the viscosity, calcium ion activity, and shear modulus during the reaction. Structural information was also obtained from the dependence of viscosity and compressive modulus on the calcium concentration in model systems. The gelation time is primarily controlled by the concentration of Na4P2O7 in solution acting as a retarder, while the level and particle size of the alginate and CaSO4 X 2H2O also affect the kinetics through the dissolution rates and concentration effects. The Ca2+ crosslinks bridging the alginate chains in the network appear to be labile. Although this process of bond interchange and that of continued polymerization during deformation may be contributory mechanisms to permanent set, bond rupture appears to be the primary mechanism. Bond rupture can be reduced by increasing the alginate content in the system which also raises the tear energy. Both the permanent set and tear energy are affected by the filler particle morphology.

Alginates↗