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At least 235 records · Page 13Linked to original sources
PubMed1996

Dimensional stability of seven elastomeric impression materials immersed in disinfectants.

Dental impressions can increase the transmission of microorganisms and infections. The purpose of this study was to assess the influence of three disinfectant solutions on the dimensional accuracy of seven elastomeric impression materials. Impressions of a test block were either left untreated (controls) or treated by immersion in a disinfectant solution. Measurements were taken on die stone replicas of the impressions. Comparisons were made between (1) the measurements for the variations in the nontreated impressions and those for the treated impressions and (2) measurements for the treated impressions and the test block. Results indicated that the aminoamphoteric agent or glutaraldehyde derivative-based solutions created little change in relation to the initial dimensional accuracy of the impression products. However, the sodium hypochlorite solution often leads to expansion by comparison with controls. By comparison to the test block, this expansion then makes it possible in most cases to obtain better dimensional accuracy than initially. Within the limits of this study this expansion could lead to an improvement in clinical fixed prosthodontic procedures.

Aldehydes↗
PubMed1999

Compressibility of two polyvinyl siloxane interocclusal record materials and its effect on mounted cast relationships.

STATEMENT OF PROBLEM: Addition silicones (polyvinyl siloxanes) are universally accepted as accurate and stable impression materials. They have also gained popularity as interocclusal record materials. However, it has not been defined if it is possible to work with polyvinyl siloxanes without changing the recorded maxillomandibular relations. PURPOSE: This study examined the compressibility of 2 addition silicones as interocclusal record materials, analyzing the changes of maxillomandibular relations at the condyle region when different compressive forces are used to stabilize articulated casts. MATERIAL AND METHODS: Sixteen interocclusal records, obtained from the same patient (8 of each polyvinyl siloxane, Blu-Mousse, Fast Set), were interposed between the patient casts in a new measuring system obtaining 48 curves of load versus maxillomandibular positional changes in 3 axes (x, y, z). These curves were compared with curves obtained with the casts in maximum intercuspation without interocclusal records (reference curves). Analysis of variance was used to compare maxillomandibular positional changes among the 3 groups (n = 48 each): Blu-Mousse, Fast Set, and control group or maximum intercuspation without interocclusal record. RESULTS: There was no significant change in maxillomandibular relations when forces up to 1 kgf were applied to stabilize the casts related by means of Blu-Mousse and Fast Set addition silicone interocclusal records. CONCLUSION: It is possible to use these polyvinyl siloxanes as interocclusal record materials without changing the recorded maxillomandibular relations.

Analysis of Variance↗
PubMed1991

[Impression materials. Dimensional stability after pouring].

The Authors wanted to establish which could be for every impression material tested, the most favourable moment for the development of plaster models in a steady environment conditions of temperature and relative humidity. From the analysis of the results obtained, we can clearly conclude that every material examined offers an ideal time interval in which we have to cast the model in plaster. This study aspires to be an invitation to all operator in the sector, to repeat this experience in their work environment to know and better manage the procedures and the materials used, from the taking the impression to the executing of the plaster model.

Colloids↗
PubMed2004

Jaw relation records for fixed prosthodontics.

This article discusses and reviews general principles of jaw relation records, including the purpose of a jaw relation record and the concept of a tripod of vertical support with adequate horizontal stability to allow opposing dental casts to be mounted accurately on an articulator. The use of the maximum intercuspal position for the vast majority of patients is favored when the goal of restorative treatment is to maintain a patient's pretreatment intercuspation and vertical dimension of occlusion. In addition, articulator choice, purpose of a face bow, and materials for jaw relation records are discussed. Common errors in making impressions, pouring impressions,mounting casts, and making interocclusal records are elucidated, providing the practitioner important information with which to avoid inaccuracies that may lead to additional time spent making intraoral occlusal adjustments at the insertion of fixed restorations.

Dental Articulators↗
PubMed2000

The influence of five impression techniques on the dimensional accuracy of master models.

A high-grade steel model with different preparation angles of 3 degrees, 7 degrees and 11 degrees in one- and two-step impression techniques were made for the determination of the influence of the preparation angle on the dimension loyalty of the resulting master casts. Using a 3-D-measuring instrument, analysis of the data showed that with the correction technique the model abutments led to a reduction in dependency on the preparation angle. The general reduction in stump height of the abutments was independent of the preparation angle. The double-mix technique showed decent increased abutments and is thus recommended for impressions of supragingival preparations.

Analysis of Variance↗
PubMed2001

Wastage of a silicone impression material in a general practice setting: a comparison between hand and automixing methods.

A practice-based, randomised, controlled trial has been undertaken to investigate the wastage of impression material when recording full arch one-stage, polyvinyl siloxane impressions using four techniques: putty and automix light viscosity material, putty and automix regular viscosity material, putty and tubed light viscosity material, and putty and tubed regular viscosity material. A total of 100 maxillary impressions, comprising 25 recorded using each of the four techniques, were obtained according to a predetermined scheme for randomisation. All material wasted in dispensing, mixing and applying each impression was determined by repeated weighing. Statistical comparisons of the mean weights of material wasted for each type of impression revealed that significantly (P < 0.01) less wastage occurred with the automix techniques. It is concluded that automix impression techniques may, in more extensive studies, be found to be more cost effective than tubed impression material techniques when recording impressions of the type investigated.

Cost-Benefit Analysis↗
PubMed1989

[Evaluation of accuracy and the time-dependent dimensional stability of silicone based impression materials].

In the recent years, silicone elastomeric impression materials are widely used in prosthetic dentistry. The accuracy and dimensional stability of these silicone elastomeric impression materials affect the success in their clinical usage. In this study, accuracy and the time-dependent dimensional stability of silicone based impression materials were evaluated. The effect of time is important when using silicone elastomeric impression materials. The result of this study clearly indicated that the silicone impression should be poured as soon as possible.

Dental Impression Materials↗
PubMed2001

A custom impression tray made with the aid of an existing prosthesis: a clinical technique.

Prostheses for patients with intraoral defects usually have complex contours. The replacement of a successful prosthesis is more readily accomplished with the aid of a custom impression tray that reproduces the contours of the existing prosthesis. In the technique presented, an irreversible hydrocolloid impression is made of the intaglio surface of the prosthesis to be replaced. Autopolymerizing acrylic resin tray material is poured into the impression, creating a custom impression tray. This procedure can simplify the impression process and reduce the need for multistep impression techniques.

Acrylic Resins↗
PubMed1980

[Reproduction of the abutment clearance in casting fixed tooth replacements].

After casting one model with various procedures and materials, models were constructed of Duroc. the abutment distance of the Duroc model depended on the impression method and the impression material. In general, double-mix impressions were more accurate than corrective impressions. Corrective impressions could be improved by placing flow-off grooves in the primary impression.

Dental Abutments↗
PubMed1985

Simplified techniques for the preparation and use of reversible hydrocolloid impression material.

The use of a simple technique with an inexpensive syringe loaded with heavy-body tray material resulted in a savings of preparation time and storage space in the conditioning unit. Only one type of material needs to be liquefied. The use of the heavy-body material in syringe and tray in conjunction with a hydrophilic technique have practically eliminated the annoying problem of tearing of the material in the gingival crevice on removal of the impression. Moisture control is no longer an aggravating problem.

Colloids↗
PubMed1992

An update of a one-appointment master impression and jaw relation record technique.

Dentists may want to consider using an update of a unique complete denture technique that saves total chair time and, therefore, decreases cost. The technique combines appointments two and three, during which time the dentist both makes the master impressions and records the maxillomandibular relationships. In the past, protection of the maxillomandibular relationship records during the subsequent laboratory work was a problem. By applying new, tough, and thin denture base materials to the technique, the dentist will be less likely to distort the maxillomandibular records while boxing and pouring the impressions.

Dental Impression Materials↗
PubMed2006

[Full arch impression techniques utilizing addition type poly vinyl siloxane for fabrication of tooth born fixed partial dentures].

A precise impression is necessary for fabricating an accurately fitting cast restoration. For this purpose, Polyvinyl Siloxane (PVS) impression materials are extremely popular because of their combination of excellent physical properties, handling characteristics and dimensional stability. Its excellent clinical features remain unaffected if simple measures are guarded. This review presents several impression techniques using PVS and recommends the one that provides the most accurate impression, utilizing the superior qualities of the PVS. The one step impression technique where no control of wash bulk and thickness exists, is considered to be the least accurate impression method with measured discrepancies as large as 7 times the original inter preparation distance and 40 times the original cross arch dimensions. Furthermore, the direct contact between the less refined putty material and the tooth preparation, as well as the high prevalence of air bubble entrapment, seriously compromises restoration longevity. The two stage impression technique has proved to produce the most accurate and reliable impressions due to complete control of the wash bulk and thickness entailed. The ideal wash bulk thickness should range between 1 to 2.5 mm all around the abutment tooth in order to minimize distortion of its subsequent die. Using a "Putty Tray" at the first stage with a predetermined space encircling the abutments will allow the wash to flow to its ideal uniform bulk size at the second stage. A uniform bulk size will prevent differential setting contraction and uneven changes at the dimensions of the die. The easiest and most clinically applicable method to achieve the desired space around the preparations is by loading the Putty material with the temporary crowns in place, followed by their removal at the second stage and occupation of the created space by the wash. In general, less control of wash bulk will result in either insufficient or excessive wash material which will determine uneven dimensional changes in the impression. This, in turn, will produce ill fitting cast restoration.

Dental Impression Materials↗
PubMed2003

Use of transparent polyvinylsiloxane to replicate gingival peri-implant soft tissue.

The fabrication of an esthetic implant-supported restoration often necessitates consideration of the surrounding gingival architecture. Procedures for generating a definitive cast that accurately details the peri-implant soft tissue with a resilient material have been described. Currently used gingival replicating materials are usually pink and opaque, making it difficult or impossible for the dentist and laboratory technician to visually confirm complete seating of components subgingivally on laboratory analogs without altering the cast. This article describes a technique for fabricating a definitive cast using a transparent polyvinylsiloxane material to replicate the peri-implant gingiva.

Dental Abutments↗
PubMed1979

[Removable partial denture. Excerpts from the literature 1977--1979].

In partial denture prosthesis research and advances were made principally on: -- the fundamental biomechanical properties of the demodont and the fibromucosa. In the light of these findings, the justification of stressbreaking as a principle is questioned -- the mechanical properties of chromium-cobalt alloys -- checking of castings by radiography -- simplification of the designs for removable partial denture frameworks -- impression materials and techniques (fluid-wax functional impression and altered cast-procedure) -- the combination of restauration and plaque control for successful dentistry.

Biomechanical Phenomena↗
PubMed1990

The effect of time on the adhesion of light-body to heavy-body Express in the two-step reline polyvinylsiloxane impression technique.

Often times light-body wash (LB) cannot be added to the heavy-body putty (HB) within 30 minutes when utilizing the two-step reline impression technique. The purpose of this study was to add the LB to the HB at times greater than 30 minutes and test the tensile bond strength. A split aluminum mold which created a bonding area of 1.13 cm2 and tray were filled with Express HB. After HB set the Express LB in a tray was added at varying times. The split molds were then separated and samples tested on the Instron. Ten groups with five samples/group (determined by a pilot study) were made. The times which the LB was added to the set HB and tested were: A) Immediately (one-step procedure); B) 10 minutes and contaminated with saliva (negative control); C) 10 minutes; D) 30 minutes; E) 45 minutes; F) 1 hour; G) 3 hours; H) 24 hours; I) 115 hours; and J) Freshened after 3 months. The results of this study indicate that saliva-contaminated samples were weaker than all other groups (P less than or equal to 0.01) and as far as tensile bond strength between materials is concerned, there appears to be no detrimental effect in tensile bond strength between HB and LB when delaying the application of the light-body material (P less than or equal to 0.01).

Dental Bonding↗
PubMed2005

A comparison of dimensional accuracy between three different addition cured silicone impression materials.

Ten impressions of a metal implant abutment were made with each of three addition-cured silicone impression materials. Using the technique of co-ordinate metrology, the shoulder region of the abutment and corresponding regions of both impressions and dies made from these impressions were scanned and measured. Comparison of these measurements indicated that the mean dimension measured from the shoulder region for each group of impression materials was significantly different from those taken from the original metal implant abutment. However, when these impressions were cast in a gypsum based die material, none of the measured dimensions taken from the casts were significantly different from those taken from the original metal implant abutment. Thus, any change in measured dimensions occurring during impression making, was compensated for in some way by the casting process.

Calcium Sulfate↗