Universal paradigms for predictable final impressions

The master blueprint for indirect restorations is the final impression. The challenge for the clinician is to establish a protocol that ensures a predictably excellent final impression.The purpose of this article is to provide a protocol that integrates the many detailed steps of impression making, from patient comfort to dental laboratory communication. Understanding the biology of the dentogingival junction, dental materials and their interactions, and proper technique all contribute to the final results.     

Medium-viscosity polyether impression material: a case report

Polyethers are elastomeric materials commonly used for making precision impressions. They are hydrophilic, which facilitates the contact of the unset material with the intraoral tissue and the wetting of the impression by cast materials. The final hardness of this new impression material is reduced in an attempt to overcome rigidity of the set impression. A case is described involving the restoration of a fractured maxillary premolar and a single-phase impression technique using the new polyether impression material.     

Microstomia in a maxillectomy patient: A prosthetic challenge

The provision of a satisfactory denture in case of reduced stomal inlet has always been a trouble for the patient and a challenge to the prosthodontist. Fabrication of complete and removable partial denture prosthesis requires accurate diagnostic impression and diagnostic casts for the development of custom trays and final impression. The decreased mouth opening, technically called "Microstomia," poses problems in tray selection, impression making, jaw records and denture insertion. The causes for microstomia are numerous, one major cause being the after-effect of radiation therapy. Whatever the cause, the ability to make impressions and jaw records becomes taxing. A variety of impression techniques using modifications in the nature of the tray and impression materials are required. The present case report highlights an innovative and different aspect of impression making and fabrication of an obturator prosthesis for a microstomic patient who underwent maxillectomy.     

The Results of a Brief Survey of Complete Denture Prosthodontic Techniques in Predoctoral Programs in North American Dental Schools

A brief mail survey of North American dental schools was undertaken to ascertain the current techniques in complete denture prosthodontics regarding preliminary and final impressions, record bases, and denture teeth. Of the 64 schools surveyed, 54 responded (84%). Seventy-four percent of the respondents used only irreversible hydrocolloid (alginate) for their preliminary impressions; 15% used only modeling plastic impression compound. Eighty-one percent used only modeling plastic impression compound for border molding of the final impression tray; 7% used only polyether impression material. Forty-eight percent used only polysulfide rubber (PR) impression material for their final impression material; 4% used only polyether impression material. Only 1 school still used shellac as one of its materials for record bases. Thirty-five percent used only Triad; 35% used only acrylic resin; 24% used both of these materials. Thirteen percent of responding schools used only nonanatomic teeth. The majority (54%) used all three options (nonanatomic, semianatomic, and anatomic). Eleven percent used lingualized occlusion. As compared with a survey performed in 1985, the use of irreversible hydrocolloid as a preliminary impression material, the use of visible light-cured resins for record bases, and the use of anatomic teeth have increased. The use of plastic impression compound for border molding and PR as the final impression material has largely remained the same.     

Polyvinyl siloxane impression materials: a review of properties and techniques.

Polyvinyl siloxane impression materials have been shown to have excellent properties as impression materials; however, they are sensitive to manipulative variables. Several methods of using very high viscosity (putty) materials to form "trays" to obtain uniform bulk of the wash impression are described, and the disadvantages of each of these techniques is pointed out. It is recommended that for best results acrylic resin custom trays should be used routinely. The interaction of polyvinyl siloxane materials with latex products is also discussed and problems that this inhibition can cause are stated. Suggestions to avoid this interaction are outlined. One of the disadvantages of the impression materials is that it has a relatively short working time. Refrigerating the material will increase working time without affecting accuracy.     

Boxing impressions with irreversible hydrocolloid

A boxing method that uses irreversible hydrocolloid for boxing final impressions made with four different final impression materials was described. The boxing material separated from the impression in one piece with all impression materials. No separation media was required. In addition, the accuracy of the borders of all impression materials was equally well preserved.     

Current concepts and techniques in complete denture final impression procedures

PURPOSE: In 2001, a survey of U.S. dental schools was conducted to determine which concepts, techniques and materials are currently prevalent in the teaching of final impression procedures for complete dentures in the predoctoral clinical curriculum. MATERIALS AND METHODS: The questionnaire was mailed to the chairperson of the prosthodontic/restorative departments of 54 U.S. dental schools. Of these, 44 schools returned the completed survey resulting in a response rate of 82%. RESULTS: Results from this survey show that the majority of schools (71%) teach the selective-pressure technique for final impression making; the majority of the schools (64%) use modeling plastic impression compound for border molding the final impression tray; 39% of the schools do not place vent holes in the final impression tray, 30% of schools place more than one hole and 27% place one hole only; the majority of the schools (98%) are using custom trays for final impressions. Ninety-eight percent of the schools are border molding the custom tray and 70% of schools are using a visible light-cured (VLC) composite resin material to make the trays. Thirty-six percent of the schools are teaching the Boucher impression technique and 34% are teaching the modified Boucher impression technique. CONCLUSIONS: Predoctoral clinical complete denture educational programs agree on many aspects of final impression making, however, there is variability in their teachings regarding the impression philosophy and the materials used.     

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口腔印模的质量直接影响修复体的准确性和修复质量。临床常用的口腔弹性印模材料有藻酸盐水胶体印模材料、琼脂水胶体印模材料、硅橡胶印模材料、聚醚橡胶印模材料和聚硫橡胶印模材料。各种材料组成不同,性能各异,临床使用时应根据具体病例,选择合适的印模材料和消毒方法,以获取最佳效果。本文主要介绍了各弹性印模材料性能特点及临床使用注意事项。     

A functional open-tray impression technique for implant-retained overdenture prostheses

Several implant impression techniques with different materials have been described in the literature. Generally, border molding, functional, and final impressions have been made with 3 different materials, which makes the procedure technique-sensitive and time-consuming. A combination of open-tray and functional impression techniques is described in this technical report. Border molding and functional impression procedures are made at the same time using a vinyl polysiloxane impression material, which makes this technique a simple and time-efficient alternative for clinicians.     

A review of contemporary impression materials and techniques

The contemporary restorative dentist has a host of impression materials available for making impressions in fixed prosthodontics,implant dentistry, and operative dentistry. With proper material selection and manipulation, accurate impressions can be obtained for fabrication of tooth- and implant-supported restorations. This article outlines the ideal properties of impression materials and explains the importance of critical manipulative variables. Available impression materials are analyzed relative to these variables, and several "specialized" impression techniques are described. Special attention is paid to polyvinyl siloxane impression materials because they have become the most widely used impression material in restorative dentistry.     

An Alternative Approach in Fabrication of Fixed Complete Dentures Using a Duplicate Denture

The traditional prosthetic steps in the fabrication of a fixed complete denture after implant osseointegration include final impression, verification of implant positioning in the working cast, mounting of the working cast, and mock denture wax trial insertion prior to the laboratory fabrication of the metal substructure; however, in patient scenarios of immediate loading of implants, the interim conversion prosthesis can be used to advance from the final impression to the milling of the underlying framework in one appointment. Consistency in the initial wax trial insertion, radiographic guide, and intraoral positioning of the conversion prosthesis can result in a well‐designed definitive prosthesis in less time with the use of the existing duplicate complete denture.     

A wash technique using rubber-base impression material

The rubber-base impression materials are versatile and extremely accurate when the procedures are sound. A simplified technique using a preliminary impression of heavy-bodied material and a final wash impression of light-bodied, rubber-base impression material has been described. This technique reduces considerably the occurrence of voids or defects in the impression and gives good detail. In addition, the preliminary rubber-base impression can be used to construct temporary acrylic resin restorations.     

A predictable and accurate technique with elastomeric impression materials

A method for obtaining more predictable and accurate final impressions with polyvinylsiloxane impression materials in conjunction with stock trays is proposed and tested. Heavy impression material is used in advance for construction of a modified custom tray, while extra-light material is used for obtaining a more accurate final impression.     

Full band impressions

Complete impression with rings achieves the same definition than complete impressions alone and gives a final quality similar to unitary guided impressions. The required steps are the following: 1st clinical: adjustment of the unitary rings, laboratory: elaboration of metallic resin boxing and individual tray, 2nd clinical: complete impression with rings. This method is of a particular interest because of its facility and its possible adaptations to various impression pastes or clinical situations. No gingival conditioning is required to the impression, and increased indications of the method can thus be seen when esthetics or periodontal conditions are a priority.     

Double arch impressions for simplified restorative dentistry

Use of a double arch, closed-mouth technique as described in this article enables dentists to obtain cast and die placement in centric occlusion in a single step. Complete closure of the teeth is mandatory for registering the interocclusal relationship correctly. The accuracy of the interocclusal relationship is more likely because of the decreased number of steps in the technique. Several different trays are available for the double arch impression technique. The more rigid trays buttress the impression material and reduce the possibilities of distortion in the final impression. Several variations in the double arch impression technique are possible, and tray selection is dependent on the demands of each patient.     

An implant-retained auricular impression technique to minimize soft tissue distortion

Achieving adaptation of an auricular prosthesis begins with an accurate impression. It is important to consider how the selection of the impression materials will affect the final outcome of the prosthesis. A procedure is presented to minimize the distortion of the soft tissues caused by the impression materials and procedure. The procedure consists of splinting the implant impression copings, then recording the soft tissue in silicone impression material, followed by the application of acrylic tray resin to provide rigidity.     

A method for making matrix material dead soft

The method described uses a denture flask as a ?ing border for impressions instead of beading and sheet wax. Vigorous vibrating movements can be applied to the artificial stone as it sets without distortion or damage to the border of the impression. When wax or thermoplastic impression materials are used for the final impression, the flask should be immersed in cold water as the plaster foundation and artificial stone set. This measure dissipates the heat given off by these materials during setting.     

Application times for the single-step/double-mix technique for impression materials in clinical practice

Hydrophilicity of unset impression materials underlies changes occurring during working time. Hence, the clinical application time when impression materials contact oral tissues after mixing may play a critical role in successful impressions. The aim of this study was to analyze the clinical time course of impression taking applying the single-step/double-mix technique. Application times of 86 impressions, comprising 265 prepared teeth and 46 implants, taken by 14 different clinicians at a university dental clinic were analyzed. The mean time from loading the impression tray until its final position in the patient's mouth (total application time) was 51.2 seconds; confidence intervals were 46.9 (lower limit) and 55.5 (upper limit). The number of registered teeth and implants did not influence the duration of impression taking. Related to wettability data, several polyvinyl siloxane impression materials show decreased hydrophilicity with respect to estimated application times. The authors suggest considering clinically relevant application times for impression taking in future in vitro studies on physicochemical characteristics of impression materials.     

A study of the reproducibility of the functional denture space with a dynamic impression technique.

A study was made on four patients to determine the reproducibility of the outer form of the buccal and lingual flanges of a complete lower denture as developed by functional movements of the surrounding tissues. 1. Two dentists participated in the study to find out the operator effect when making impressions for the functional form of the flanges. 2. Two tissue-conditioning impression materials were used to determine if the characteristics of the impression material had any effect on the final form. 3. The impression materials were applied to the denture flanges by two different methods. 4. The impressions were placed in a mitre box, stabilized with plaster, and sectioned in the molar, premolar, and incisor regions. This provided five cut surfaces for measuring. 5. Each section was measured at five to six representative distances. 6. The differences in the flange form measurement and the distances among the impressions made with the same technique and material were small, and the reproducibility can be considered clinically acceptable. 7. There were statistically significant differences in the flange form measurement distances among the different materials and method of application of the material.     

Impression technique for denture reconstruction.

The advent of tissue conditioning materials has made possible a new method for recording functional impressions for denture reconstruction using the patient's existing dentures as impression trays. The criteria by which the suitability of existing dentures for use in the technique are set out in detail. A particular feature of the method is the physiological recording of the post palatal seal area using Iowa wax and its incorporation into the entire maxillary impression. The advantages of the technique include the possibility of recording the tissues under physiological displacement resulting from normal function over a prolonged period rather than at the moment of final setting of conventional impression materials.