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Journal of the American Dental... Dec 1949
Topics: Dental Impression Materials; Dental Materials; Humans
PubMed: 15393828
DOI: No ID Found -
Dental Materials : Official Publication... Jul 2012To study the role of the various components of alginate dental impression materials. (Comparative Study)
Comparative Study
OBJECTIVE
To study the role of the various components of alginate dental impression materials.
METHODS
Experimental materials were formulated and their physical properties characterized and compared to commercially available counterparts (Neocolloid, Palgat Plus and Blueprint Cremix). Properties examined were: dimensional stability and weight change in water and artificial saliva; setting behavior; Shore A hardness and tear energy. The role of magnesium oxide was also investigated.
RESULTS
Weight changes in water and artificial saliva can be attributed to an initial thermodynamic potential owing to the ionic content of the alginate, causing water to diffuse into the material. Water is then driven back out following a reversal of this potential. Hardness results for experimental materials were within the range obtained from the commercial materials. The hardness value for an experimental formulation that did not contain magnesium oxide was lower than values from the other experimental materials that did. Tear energies for all three experimental materials were greater than those of the commercial products. There were statistically significant differences between the two experimental materials that contained magnesium oxide and one that did not. With regard to setting time, statistically significant differences were seen between commercial materials and two of the experimental materials. The experimental material that did not contain magnesium oxide had a considerably longer setting time than all of the other materials tested.
SIGNIFICANCE
The key role of magnesium oxide in the setting reaction and the effect on hardness have been demonstrated and discussed.
Topics: Alginates; Chemistry, Physical; Dental Impression Materials; Hardness; Magnesium Oxide; Materials Testing
PubMed: 22575742
DOI: 10.1016/j.dental.2012.03.012 -
Acta Odontologica Scandinavica Nov 2014Vinyl polysiloxane (VPS) is elastomeric dental impression material which, despite having very few reports of adverse reactions, has shown high levels of cytotoxicity...
OBJECTIVES
Vinyl polysiloxane (VPS) is elastomeric dental impression material which, despite having very few reports of adverse reactions, has shown high levels of cytotoxicity that is difficult to be interpreted without referencing to the positive control material. Therefore, in this study, positive control VPS was developed using sodium lauryl sulfate (SLS) for the reference of cytotoxicity test.
MATERIALS AND METHODS
The positive control VPS with SLS was formed with a different proportion of SLS (0, 1, 2, 4, 8 and 16 wt%) added to the base. The cytotoxicity test was then carried out using the extractions or dilutions of the extractions from each of the test samples using murine fibroblast cells (L929).
RESULTS
The final product of positive control VPS behaved similar to commercially available VPS; being initially liquid-like and then becoming rubber-like. Ion chromatography showed that the level of SLS released from the product increased as the proportion of added SLS increased, consequently resulting in an increased level of cytotoxicity. Also, the commercially available VPS was less cytotoxic than the positive control VPS with more or equal to 2 wt% of SLS. However, even the VPS with the highest SLS (16 wt%) did not cause oral mucosa irritation during the animal study.
CONCLUSIONS
The positive control VPS was successfully produced using SLS, which will be useful in terms of providing references during in vitro cytotoxicity testing.
Topics: Animals; Cell Line; Chromatography, Ion Exchange; Cricetinae; Dental Impression Materials; Fibroblasts; Materials Testing; Mesocricetus; Mice; Mouth Mucosa; Polyvinyls; Siloxanes; Sodium Dodecyl Sulfate; Sulfates; Surface-Active Agents; Time Factors
PubMed: 24471730
DOI: 10.3109/00016357.2013.879996 -
The Journal of Prosthetic Dentistry Sep 2003Irreversible hydrocolloid is widely used as an impression material for fabrication of extraoral maxillofacial impressions. A disadvantage of irreversible hydrocolloid,...
STATEMENT OF PROBLEM
Irreversible hydrocolloid is widely used as an impression material for fabrication of extraoral maxillofacial impressions. A disadvantage of irreversible hydrocolloid, however, is its limited working time.
PURPOSE
This study tested the compression strength (elastic recovery) and working and setting times for an irreversible hydrocolloid impression material after a retarder was added.
MATERIAL AND METHODS
The irreversible hydrocolloid (Jeltrate) was mixed with water in a standard water/powder mixture of 18 mL (1 unit) of water and 7 g (1 unit) of the impression material. Test specimens (n = 3) were prepared by adding 2, 4, 6, and 8 drops of monobasic sodium phosphate (the retarder) to each. Three other specimens, to which no retarder was added, served as the control. Specimens were prepared according to the American National Standards Institute/American Dental Association's specification no.18 guidelines for irreversible hydrocolloid impression material. Immediately after the specimens were prepared, the flat end of a polished rod of poly(methyl methacrylate) was placed in contact with its exposed surface and quickly withdrawn. The working-time experiment was a pass/fail test conducted 30 seconds before the initial setting time. The initial setting time was established as extending from the start of the mix to the time when the impression material no longer adhered to the end of the rod. To determine how the compressive strength of the modified irreversible hydrocolloid (with retarder added) compared with that of the control, the mean stress at maximum load (Mpa) was analyzed. The compressive strength (MPa) was calculated. Statistical analysis consisted of descriptive statistics and regression analyses.
RESULTS
The results of this experiment demonstrated that the elastic recovery of the irreversible hydrocolloid did not change with the addition of sodium phosphate (2 to 8 drops). The percent recovery with was 95.95% +/-.42%, 96.33% +/-.82%, and 96.28% +/-.53% for 0 (control), 2 and 8 drops, respectively. Average setting times for control specimens were 2 minutes 20 seconds +/- 0 seconds for the control specimen (0 drops) to 11 minutes 20 seconds +/- 1 minute 50 seconds for the test specimen with 8 drops. There was a direct relationship (R(2) = 0.85) between the number of drops added and the setting time. All control specimens and test specimens containing 2, 4, 6, and 8 drops of monobasic sodium phosphate produced acceptable levels of elastic recovery (> or =95%).
CONCLUSION
Within the limitations of this study, predictable longer working and setting times were demonstrated for the irreversible hydrocolloid specimens with 1 to 8 drops of the sodium phosphate solution tested. The specimens with 8 drops of retarder solution exhibited variable setting times and would not be suitable for clinical use. The compressive strength of the modified irreversible hydrocolloid material tested was compromised because of the addition of sodium phosphate solution; however, recovery from deformation remained satisfactory as retarder solution was added.
Topics: Alginates; Colloids; Compressive Strength; Dental Impression Materials; Dental Stress Analysis; Elasticity; Materials Testing; Maxillofacial Prosthesis; Organic Chemicals; Phosphates; Regression Analysis; Time Factors
PubMed: 12942062
DOI: 10.1016/s0022-3913(03)00366-4 -
Quintessence International (Berlin,... Feb 2007Impression techniques in restorative dentistry require displacement of gingival tissues to expose subgingival finish lines on tooth preparations. Retraction cords are... (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVES
Impression techniques in restorative dentistry require displacement of gingival tissues to expose subgingival finish lines on tooth preparations. Retraction cords are commonly used for this purpose. Some cord systems include various medicaments, which may remain in the sulcus after retraction procedures. The purpose of this study was to determine whether any of the commonly used gingival retraction medicaments could influence the surface characteristics of the impression material and to evaluate the clinical performance of retraction cords.
METHOD AND MATERIALS
Sixteen cord systems in various shapes, sizes, and medications were used in this study. The clinical performances of cords were evaluated with a blind experimental study design, according to predetermined criteria. Results were analyzed by using chi-square test and ordinal logistic regression analysis (P <.05).
RESULTS
Statistically significant differences were found in all criteria among groups (P <.05). None of the materials investigated appeared to have any influence on the surface characterization of the polyvinyl siloxane impression material used. Better impression qualities were observed in groups with easy insertion, proper dilatation, less recurrent bleeding, and no remnants or fraying. Logistic regression analysis revealed that both retraction cord medicaments (odds ratio = 0.63, P = .00 <.05) and cord thicknesses (odds ratio = 2.09, P = .00 <.05) were important risk factors on the gingival margin quality.
CONCLUSIONS
The applied gingival retraction cord systems had no influence on the surface characterization of the polyvinyl siloxane material tested. Gingival margin quality of the impression and clinical application procedures were affected by the retraction systems. Untreated, medium-braided, and epinephrine-impregnated cord systems were clinically successful. However, the potential systemic effects of epinephrine must be considered.
Topics: Adolescent; Adult; Aged; Dental Cavity Preparation; Dental Impression Materials; Dental Impression Technique; Female; Gingiva; Hemostasis; Humans; Logistic Models; Male; Middle Aged; Odds Ratio; Single-Blind Method; Surface Properties
PubMed: 17510720
DOI: No ID Found -
Journal of Oral Rehabilitation Mar 2003The purpose of this investigation was to evaluate the tensile bond strengths of two impression material systems (polysulphide and polyvinyl siloxane) to two custom tray...
The purpose of this investigation was to evaluate the tensile bond strengths of two impression material systems (polysulphide and polyvinyl siloxane) to two custom tray materials [autopolymerizing and visible light-cured (VLC) acrylic resin]. The effect of polymerizing the tray materials directly against wax spacer and tin foil was evaluated for each material. Polymerizing tray materials against tin foil significantly increased the bond strengths of polysulphide and polyvinyl siloxane impression materials to VLC and autopolymerizing acrylic resin tray materials. Polyvinyl siloxane VLC cured against tin foil combination produced the strongest bond. The VLC resin tray material generated greater bond strength than autopolymerizing acrylic resin when polymerized against tin foil.
Topics: Acrylic Resins; Adhesiveness; Dental Impression Materials; Humans; Macromolecular Substances; Materials Testing; Polyvinyls; Siloxanes; Sulfides; Tensile Strength; Waxes
PubMed: 12588506
DOI: 10.1046/j.1365-2842.2003.01023.x -
The Journal of Prosthetic Dentistry Sep 2014
Topics: Dental Clasps; Dental Impression Materials; Dental Impression Technique; Denture Design; Denture, Partial, Removable; Humans; Lubricants; Polyvinyls; Siloxanes
PubMed: 24657176
DOI: 10.1016/j.prosdent.2013.11.014 -
Scandinavian Journal of Dental Research Aug 1991According to the so-called double-mix technique for impression taking, a material of high and one of low viscosity set against each other. We found that a distortion of...
According to the so-called double-mix technique for impression taking, a material of high and one of low viscosity set against each other. We found that a distortion of the joined materials occurred which may compromise the precision of the impression. The distortion of such combinations of materials of high and low viscosity was measured on beam-like specimens. Significant differences between materials were observed. The phenomenon may be explained by a swelling of the material of low viscosity. The swelling may be associated with a diffusion of unreacted compounds from the material of high viscosity into the material of low viscosity. Measurements of the swelling of specimens immersed in the catalyst component of unset material showed an increase in length of 2-5%.
Topics: Dental Impression Materials; Dental Impression Technique; Diffusion; Immersion; Polyvinyls; Siloxanes; Surface Properties; Time Factors; Viscosity
PubMed: 1771382
DOI: 10.1111/j.1600-0722.1991.tb01039.x -
Quintessence International (Berlin,... 2003Aspiration of foreign bodies is a serious complication that may occur during the course of dental treatment. A case report of a 60-year-old man with recurrent pneumonia...
Aspiration of foreign bodies is a serious complication that may occur during the course of dental treatment. A case report of a 60-year-old man with recurrent pneumonia is presented. One year after the onset of his initial symptoms, a hard substance that made a complete mold of the bronchial tree at the inferior right lobe was extracted with a rigid bronchoscopy. This green material of elastic consistency was dental impression material (polyvinylsiloxane). On careful questioning, the patient indicated that he had dental impressions taken 2 months before the onset of the symptoms. Surgery was indicated and lobectomy of the inferior right lobe was performed without incident. To avoid this complication, some preventive precautions such as identifying high-risk patients; using rubber dam; tethering any small instrument with a ligature; placing a gauze screen to protect the oropharynx in sedated patients; and using custom impression trays to minimize the amount of impression material required have been suggested. In case of a suspected aspiration, the patient must be referred to appropriate medical care.
Topics: Bronchi; Bronchoscopy; Dental Impression Materials; Foreign Bodies; Humans; Male; Middle Aged; Pneumonia, Aspiration
PubMed: 14620270
DOI: No ID Found -
Journal of the American Dental... Jul 1997
Topics: Alginates; Dental Impression Materials; Dental Prosthesis Design; Ethers; Polyvinyls; Resins, Synthetic; Siloxanes
PubMed: 9231610
DOI: 10.14219/jada.archive.1997.0312