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At least 289 records · Page 16Linked to original sources
PubMed1985

Accuracy of four types of rubber impression materials compared with time of pour and a repeat pour of models.

The accuracy of four types of elastomeric impression materials was studied as a function of model location, time of pouring, and repetition of pouring. There was little change in dimension among abutment preparations for all materials, for all times of pour, and with a repeat pouring. It appears that measurements between posts are not sensitive to detecting differences between materials and that other dimensions should be examined to discern where differences might lie. The diameter of the stone post was larger than the standard for the AS and PS materials and was unchanged or smaller than the standard for the CS and the PE. The vertical dimensions of stone posts were, in general, shorter than the standard for all materials, with the AS demonstrating the smallest change. The AS and CS products demonstrated the best recovery from undercuts and the least change in dimensions between an initial and second pour of an impression. The AS and PE were the least affected with delays of 1, 4, and 24 hours in pouring the impression.

Crowns↗
PubMed1977

[A new impression method for partial dentures with special reference to the varying resiliency of the jaw mucosa and the abutment teeth].

By use of two different materials, the combination impression facilitates the preparation of models representing the oral situation without compression of the mucosa or tension at the abutment teeth. In addition, the original impression tray can be ground down without much additional effort and used for the determination of jaw relations. The otherwise necessary and additional preparation of bite blocks is no longer required.

Dental Abutments↗
PubMed2005

Using silicone impression material and acrylic resin to fabricate remount casts for removable partial dentures.

A technique is described for fabrication of a remount cast for a removable partial denture. This procedure consists of filling the occlusal/incisal third with acrylic resin and injecting polyvinylsiloxane impression material into the irreversible hydrocolloid impression. This technique provides a simple method for making a remount cast and enables the clinician to remove and easily place the partial denture on the cast during occlusal refinement procedures without damage to the removable partial denture or the remount cast.

Acrylic Resins↗
PubMed1990

An effect of tray design and material retention on the linear dimensional changes in polysulfide impressions.

One-unit fixed partial dentures, which fit accurately on the laboratory dies made from polysulfide impression materials, often pose a problem in seating completely in the mouth of the patient. Sectioning of the fixed partial denture units allows the individual units to seat accurately in the mouth but requires a soldering procedure. Linear distortion of the mercaptan (polysulfide) rubber base that takes place during setting is a cause of this problem. The distortion is directly related to (1) tray design, (2) area of adhesive placement, and (3) excessive bulk of material on the tray border during impression making. A controlled amount of adhesive and impression material in a new design for a custom tray must be used to minimize this distortion. When these factors are controlled, the resulting impression is unrestricted, and a more accurate working die is obtained. This results in a better fit of one-unit fixed partial dentures in the mouth.

Adhesives↗
PubMed1986

Comparison study of elastic impression material.

The study of four elastic impression materials indicated that master castings could be more accurately seated on casts made from MOD impressions than from full crown impressions. A discrepancy between clinical acceptance and statistical identity was also demonstrated. The study indicated that by altering just one variable, the pour time, a wide range of results is obtained, some clinically acceptable and others clinically unacceptable.

Crowns↗
PubMed2002

Factors that affect the adhesion of two irreversible hydrocolloid materials to two custom tray materials.

STATEMENT OF PROBLEM: Little evidence is available on the length of time that adhesive should be allowed to dry before irreversible hydrocolloid impression making. PURPOSE: This study investigated the effect of adhesive drying times on the bond strengths of 2 irreversible hydrocolloid impression materials to 2 "custom" tray materials. MATERIAL AND METHODS: A total of 1,632 specimens were tested: 816 in tensile tests and 816 in tests of the shear bond strength (megapascals) of 2 irreversible hydrocolloid impression materials to an autopolymerizing and a visible light-polymerizing acrylic resin tray material. In the first part of the investigation, a single coat of adhesive was applied to specimen plates that simulated the custom impression tray surface; in the second part, a second coat of adhesive was applied after the irreversible hydrocolloid was removed, and the effect of this second coating on bond strength was examined. In both parts, the adhesive was allowed to dry for a range of times (0 to 8 minutes at 30-second intervals, for a total of 17 time periods) before the addition of the impression material. The specimen plates were placed in a humidor and separated in a universal testing machine operated at a crosshead speed of 100 mm/min with 0- to 5-kN load cell. Data from each of the 1,632 specimens were collected and evaluated with analysis of variance, regression analysis, and t tests (P<.05). RESULTS: Significant differences in mean bond strengths were found between specimens with a 4-minute adhesive drying time (0.179 MPa tensile, 0.068 MPa shear) and specimens with a 0-minute drying time (0.065 MPa tensile, 0.015 MPa shear). Any period over 4 minutes produced no significant difference. The mean bond strengths of the single-coated specimens were 0.179 MPa (tensile) and 0.076 MPa (shear). These values were significantly greater than those for specimens with a second adhesive layer (0.136 MPa tensile, 0.035 MPa shear) over all time periods. Mean tensile bond strengths (0.158 MPa) were consistently higher than shear bond strengths (0.056 MPa) for all combinations of tray material, adhesive application, and time. CONCLUSION: Within the limitations of this study, the results suggest that adhesive applied to the autopolymerized and light-polymerized custom tray materials tested should be allowed to dry for at least 4 minutes before irreversible hydrocolloid is applied. Better results were obtained when the adhesive layer from a failed irreversible hydrocolloid impression was removed and replaced rather than overlaid with an additional adhesive coating.

Acrylic Resins↗
PubMed1996

Vertical distortion in distal extension ridges and palatal area of casts made by different techniques.

A coordinate measurement machine with laser probe was used to measure the vertical distortion of the casts produced by use of three types of impression materials (irreversible hydrocolloid, condensation silicone, and addition silicone) and two types of trays (stock and custom trays). Results indicated that all impression groups showed positive vertical distortion (ranging from 0.00566 to 0.30299 mm) at the edentulous ridges and palatal area. The amount of the vertical distortion was greatest at the palatal area and was followed by the high edentulous ridge and the low edentulous ridge. Addition silicone, with either custom tray or stock tray, was the most accurate impression material. Condensation silicone was more accurate than irreversible hydrocolloid in custom tray impression. However, in stock tray impression the irreversible hydrocolloid was more accurate than the condensation silicone. The results suggest that, with careful manipulation, irreversible hydrocolloid with stock tray impression may provide a satisfactory cast for fabricating the framework of a distal extension removable partial denture.

Alginates↗
PubMed2000

Comparison of impression materials for direct multi-implant impressions.

STATEMENT OF PROBLEM: Given that meticulous implant prosthodontic procedures are recommended to obtain the best possible intraoral fit, impression materials that are suitable for use with a direct impression technique warrant further investigation. PURPOSE: This in vitro study compared the amount of torque required to rotate a square impression coping in an impression and evaluated the accuracy of solid implant casts fabricated from different impression materials. MATERIAL AND METHODS: Two direct transfer implant impressions were made using 8 impression materials; the torque required to rotate an impression coping in the impressions was calculated. Ten direct transfer implant impressions were made from the master model and poured in a die stone (Resin Rock) for 3 of the 8 initial impression material groups. Linear distances between steel balls placed on each abutment replica were measured with a traveling microscope to determine distortion in the impression procedure for each group. Data were analyzed (P =.05) with ANOVA and Ryan-Einot-Gabriel-Welsch multiple range test for post hoc. RESULTS: With a 1-way ANOVA, average torque values among the material groups differed significantly (P =.001). Polyether (medium consistency) was found to produce the highest overall torque values, followed by addition silicone (high consistency), and then polysulfide (medium consistency). Statistically significant difference was also found among the 3 material groups' mean absolute cast error using a 1-way ANOVA (P =.0086). Implant casts made from polyether (medium) or addition silicone (high) impressions were significantly more accurate than casts made from polysulfide medium impressions. CONCLUSION: On the basis of the results of this study, the use of either polyether (medium) or addition silicone (high) impression is recommended for direct implant impressions.

Analysis of Variance↗
PubMed1998

Dimensional stability and detail reproduction of irreversible hydrocolloid and elastomeric impressions disinfected by immersion.

STATEMENT OF PROBLEM: Because irreversible hydrocolloid impressions imbibe blood and saliva, immersion rather than spray disinfection may be more effective. Polyether has been shown to be dimensionally sensitive to immersion disinfection. PURPOSE: The aim of this study was to determine whether irreversible hydrocolloid and polyether impressions could be disinfected by immersion without sacrificing accuracy and surface quality. MATERIAL AND METHODS: Impressions were made of a master mandibular arch containing a crown preparation. Changes between the master and working casts were assessed. Irreversible hydrocolloids (Jeltrate; Palgaflex), a polyether (Impregum F), and an addition silicone (President) were used. Disinfectants were an iodophor (Biocide), a glyoxal glutaraldehyde (Impresept de), and a phenol glutaraldehyde (Sporicidin). The control was without disinfection. Casts were formed in Type IV gypsum. The roughness of working dies was also recorded and an analysis of variance was used for statistical evaluation. Results. Casts from disinfected irreversible hydrocolloid and elastomeric impressions maintained accuracy for anteroposterior and cross arch dimensions where differences from the master was less than 0.1%. Buccolingual and mesiodistal dimensions of working dies (disinfected and control) were 6 to 8 microm larger than the master for addition silicones and 11 to 16 pm for polyethers. The occlusogingival dimension of dies for control and disinfected polyether was 9 pm longer than the master compared with -3 microm for addition silicone. The range of mean surface roughness of working dies made from irreversible hydrocolloids was 1.4 to 1.7 microm and ranged from 0.5 to 0.7 microm for elastomeric impressions. Conclusion. Immersion disinfection of Jeltrate material with iodophor and Palgaflex material with glyoxal glutaraldehyde produced casts and dies as accurate as the control. Control and disinfected elastomeric impression produced dies as clinically accurate and smooth as the master. Disinfection of irreversible hydrocolloid impressions with the glyoxal and phenol glutaraldehyde produced a surface smoother than controls.

Alginates↗
PubMed2002

Restitution of maxillary anterior aesthetics with all-ceramic components.

This paper discusses the use of four types of ceramics; zirconia, leucite reinforced glass, densely-sintered pure aluminium oxide and a low fusing porcelain, for the restitution of anterior aesthetics. Recent advances in dental ceramic technology have made this scenario a reality, which only a decade ago, was thought elusive. While ceramics offer obvious advantageous properties of enhanced appearance, they also need to satisfy functional and longevity criteria to be considered viable restorative materials. Numerous studies have cited data to fulfil these criteria, including sustained function and survival rates similar to porcelain fused to metal (PFM) restorations. This discussion will focus on current dental ceramic advances, and present a clinical case study using all ceramic constituents to rectify a deteriorating dentition.

Computer-Aided Design↗
PubMedDate not supplied

The influence of the impression tray on the accuracy of impressions for crown and bridge work--an investigation and review.

OBJECTIVE: To evaluate the accuracy of working casts for crown and bridge restorations made from twin mix putty/wash silicone elastomeric impression materials using different types of stock tray. DESIGN: A master cast was made from ivorine teeth in a mandibular model. Three teeth were prepared for full crown restorations to simulate a single unit and a three unit bridge. Impressions were taken using four different types of impression tray and two different viscosities of silicone putty, together with a wash. Full metal crowns were constructed and seated on duplicate master casts and measurements made of the marginal discrepancies. SETTING: The work was carried out in a dental technology laboratory in a university department of restorative dentistry in 1995/1996. RESULTS: Metal and rigid plastic impression trays showed the least discrepancy (about 50 microns), the latter slightly greater with the normal putty than the soft one. Impressions taken with flexible plastic trays produced considerable discrepancy with both putties, approximately 210 microns and 180 microns respectively. CONCLUSIONS: Metal and rigid plastic stock trays give greater accuracy in the putty/wash silicone twin mix impression technique compared with flexible plastic ones for crown and bridge work. Those using the latter should be aware of their shortcoming in this respect.

Crowns↗
PubMed1979

One-step border molding of complete denture impressions using a polyether impression material.

A technique has been described which uses a polyether impression material for border molding of complete denture impressions. It has the following advantages: 1. There is simultaneous molding of all borders of either the maxillary or mandibular impression. 2. Border molding can be accomplished with one insertion of the tray. 3. Functional movements performed by the patient are used in border molding. 4. The technique is easily mastered.

Acrylic Resins↗
PubMed1989

[Utility of the impression technique with the individual tray for cast crown].

This study was executed at an opportunity for taking the impressions of a full crown abutment tooth by the five different methods with the four different impression materials; the copper ring tray on the abutment method with the polysulfide rubber, the resin ring tray on the abutment method with silicone rubber, the wash technique with silicone rubber, the hydrocolloid impression technique and the hydrocolloid-alginate impression technique. The reproducibility of the preparation margin on the ten stone dies was photographically measured and the following results were obtained. 1. The reproducibility of the preparation margin was affected considerably by the following conditions. 1) The character of the impression materials, 2) the position of the preparation margin in the gingiva sulcus and 3 the undercut degree beneath the preparation margin. 2. The impression technique with the individual ring tray on the abutment showed great utility under any condition of the preparation margin on the abutment. 3. The impression method should be selected clinically according to the condition of the abutment.

Crowns↗
PubMed1994

Combination stone and resilient material for removable partial denture remount cast described and compared with two other remount cast procedures.

A procedure for making a combination remount cast of stone and elastomeric material for removable partial dentures is described in detail and is compared quantitatively with two other methods for making remount casts for removable partial dentures. This method does not require blocking out the undercuts in the denture base or around the clasps.

Calcium Sulfate↗
PubMed1998

A microbiological investigation following the disinfection of alginate and addition cured silicone rubber impression materials.

The antimicrobial efficacy of four commercially available disinfectants (Haz-tabs, chlorhexidine, Virkon and C&J Algisept Spray) was investigated. It was shown that all were effective in decontaminating the impressions whilst those placed only in sterile water, used as a control, showed variable levels of bacterial growth. Moreover, alginate appeared to carry significantly higher numbers of bacteria than addition cured silicone rubber.

Adult↗
PubMed1994

Removal of latex glove contaminants prior to taking poly (vinylsiloxane) impressions.

Sulfur compounds found in latex gloves may be deposited on teeth and gingiva, inhibiting the setting of poly(vinylsiloxane) impression materials. The objective of this in vivo study was to screen a variety of methods to remove these contaminants. Ten patients were each tested with eight decontamination methods. Before each trial, the facial surfaces and adjacent gingiva of the maxillary central and lateral incisors were contaminated with 20 wipes of a latex glove. Decontamination methods included a 30-second rinse with mouthwash, 3% hydrogen peroxide, or air-water syringe; a 30-second toothbrush scrub with water, mouthwash, or hydrogen peroxide; a 30-second cotton pellet-Cavidry scrub; and a 30-second cleaning with a prophy cup and pumice. A 10-second water rinse followed each method except the air-water syringe and Cavidry groups. A low-viscosity poly(vinylsiloxane) impression material was then used to take an impression of the area. To test surface inhibition, the gingival, tooth, and palatal impression surfaces were wiped with cotton-tipped applicators, and the degree of inhibition was subjectively categorized by two independent investigators. Mechanical decontamination with a toothbrush or pumice was significantly more effective than was rinsing alone, regardless of the solution used.

Analysis of Variance↗