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.     

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.     

Comparative evaluation of dimensional accuracy of casts generated from multiple mix impression technique,matrix impression system and dual arch impression technique – An in vitro study

For a successful fixed partial prosthodontics, obtaining an accurate impression for making an accurate cast is of prime importance.In the present study the three fixed prosthodontic impression procedures, multiple mix impression technique, matrix impression system and dual arch impression technique; have been compared in terms of dimensional accuracy. An articulated acrylic resin typodont prepared with reference points was used as a master model. Addition silicon impression materials in various consistencies were used for making impressions. The coordinate measurement machine (Lloyd, Germany) was used for three dimensional measurement of master model and stone casts with an accuracy of 0.0001 mm.As per statistical analysis, all the impressions had a tendency to be oversized in horizontal dimensions and undersized in vertical dimensions. Dual arch impression technique used with flexible disposable plastic tray has found to be less dimensionally accurate as compared to multiple mix impression technique and matrix impression system whereas the other two techniques were comparable to each other.     

Master cast accuracy in single-tooth implant replacement cases: an in vitro comparison. A technical note

PURPOSE: This in vitro study evaluated the accuracy of master casts obtained by using (1) copings modified by sandblasting and coating their roughened surfaces with impression adhesive before final impression procedures and (2) gold machined UCLA abutments as impression copings in final impression procedures for single-tooth implant replacement cases. MATERIALS AND METHODS: A polymeric resin model with a standard single implant was used to simulate a clinical situation. A group of 20 impressions were made using square impression copings sandblasted to roughen their external surfaces at a supragingival level and then coated with Impregum polyether adhesive; a second group of 20 impressions were made using gold machined UCLA abutments as impression copings. The castable part of the UCLA abutments was secured with resin to the gold machined section of the UCLA abutment to prevent movement of the castable part itself on the gold machined portion during the impression procedures; the castable portion of the UCLA was also coated with the Impregum polyether adhesive to improve the stability of the gold machined UCLA abutment inside the impression material. Master casts fabricated for both groups were analyzed to detect rotational position change of the hexagon on the implant replicas in the master casts with reference to the resin model. RESULTS: The rotational position changes of the hexagon on implant replicas were significantly less variable in the master casts obtained using gold machined UCLA abutments as impression copings than in the master casts achieved with the roughened square impression copings. DISCUSSION: Improved precision of the impression was achieved when the gold machined UCLA abutments were used as impression copings. CONCLUSION: This report suggests that using gold machined UCLA abutments as impression copings in the final impression procedures can enable the clinician to achieve a more accurate orientation of the implant replicas in the laboratory master casts for single-tooth implant replacement cases.     

Accuracy of casts produced from alginate and hydrocolloid impression materials.

It is recognized that alginate impression materials have been used to obtain casts from which castings have been fabricated for a number of years. This study indicates that more dimensionally accurate casts are produced from hydrocolloid compared with casts produced from alginate. The most accurate casts were produced from the polyether impression material.     

Technique for making flexible impression trays for the microstomic patient

This impression technique can be used for patients in whom routine use of stock impression trays is hindered by microstomia. Putty wash material can be manipulated with minimal effort and time. Placing the completed preliminary impression in a free-flowing mix of dental stone stabilizes the impression material and facilitates boxing and pouring of the impression. The resultant preliminary casts can then be used for diagnostic purposes and for making rigid sectional trays for final impressions.     

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.     

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.     

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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。     

Accuracy of one-step versus two-step putty wash addition silicone impression technique.

This study compared the accuracy of one-step putty wash with two-step putty wash impression techniques. Five addition silicone impression materials-Mirror 3 (MR), Mirror 3 Extrude (ME), Express (E), Permagum (P), and Absolute(A)--were tested. A stainless steel model containing two full-crown abutment preparations was used as the positive control. Five replications for one-step and two-step putty wash impressions of the master model were made for each test material. Accuracy of the materials was assessed by measuring six dimensions on stone dies poured from impressions of the master model. Accuracy of addition silicone impression material is affected more by material than technique. Accuracy of the putty wash one-step impression technique was not different from the putty wash two-step impression technique except at one of the six dimensions where one-step was more accurate than two-step. Mirror 3 putty wash two-step impression presented less distortion than Mirror 3 Extrude putty wash one-step or two-step impression.     

Preliminary functional impression for the mandibular complete denture

A technique for producing a preliminary impression of a resorbed edentulous mandibular ridge is presented. A 2-mm metal wire is adapted to the curve of the mandibular arch. A high-viscosity impression material is then formed to the wire and placed in the patient's mouth. Speech movements are used to functionally shape the material. Following polymerization, additional material is added to create extensions not captured in the first impression. A final wash using a low-viscosity silicone or polysulfide rubber material completes the impression. The resultant preliminary impression has the advantage of not being distorted by an ill-fitting stock tray or artificially manipulated by the clinician.     

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.     

唇腭裂新生儿的模型制取方法初探

目的 探讨一种精确、简便、安全的唇腭裂新生儿上颌模型制取方法。方法 采用普通的藻酸盐印模材料,通过适当的方法制取唇腭裂新生儿的上颌模型。结果 通过采用本文的模型制取方法,可以在临床上获得满意的唇腭裂新生儿上颌模型。结论 利用该技术可以获取理想的新生儿腭裂模型,具有精确、简便、安全等特点,为临床广泛地开展唇腭裂术前正畸提供便利。     

Evaluation of Elastomeric Impression Materials’ Hydrophilicity: An in vitro Study

IntroductionHydrophilicity of dental impression materials is crucial for obtaining an accurate impression and necessary for the production of a well-fitting cast restoration. The most common technique for evaluation of hydrophilicity is a contact angle measurement. The aim of the present in vitro study was to compare the water contact angles of four groups of elastomeric impression materials, before and during setting.Material and methodsFlattened specimens (n=10) of tested impression materials were prepared by the use of a Teflon mold with specific dimensions. A 5μl droplet of deionized water fell on the specimen, and photos were taken using a Nikon D3200 DSLR camera and a 105 mm macro lens (Nikorr, Nikon) in specific time points.ResultsThe CAD/CAM material showed the highest contact angle measurements. The light body polyvinylsiloxane (PVS) material 1, polyether and vinylsiloxanether material showed comparable contact angle measurements especially at the initial time point. A statistically significant reduction of contact angles was reported during setup time for all PVS, PE and vinylsiloxanether materials, while the most expressed reduction of contact angle measurements, and thus the most significant increase of hydrophilicity were reported for light wash PVS material 2.ConclusionsThe CAD/CAM impression material showed the most hydrophobic behavior. PVS materials showed excellent hydrophilicity. Polyether and polyvinyloxanether impression materials presented lower contact angle measurements, and thus superior hydrophilicity, compared with other tested materials initially and during setting. All tested impression materials presented a stepwise development of hydrophilicity during the setting stage.     

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.     

Nontraumatic Final Impressions for Fixed Partial Dentures

A nontraumatic, nonretraction impression technique is presented which uses the fabrication of an acrylic resin shell from an interocclusal wax impression. A crucial step in the procedure is obtaining the complete finish line of the preparation within the resin. This tray, which is filled with an elastomeric impression material, is combined with a triple tray of the same material to provide all the necessary relationships to construct a crown or coping. This procedure is especially efficient for multiple abutments during fixed partial denture construction.     

A modified impression technique for accurate registration of peri-implant soft tissues

Replacement of single missing teeth with an implant-supported restoration is recognized as a highly successful treatment. An impression technique for peri-implant soft-tissue replication in an anterior zone is described. The technique involves use of an interim restoration as an abutment for the final impression. This allows accurate duplication of the soft tissues and fabrication of a final restoration with the correct emergence profile.     

Accuracy of alginate and elastomeric impression materials

The accuracy of three alginates and seven elastomeric impression materials was determined. Impressions were taken of a truncated cone and poured with stone die. A steel ring fitting the steel cone was placed on the dies, and the discrepancy between the top surface of the ring and the die was measured. From these measurements the deviation between the base diameter of the die and that of the cone was calculated and used to express the accuracy of an impression material. All impressions showed a net shrinkage, resulting in too large a die stone and incomplete seating of the steel ring. The inaccuracy of the alginates varied between 44 and 188 microns. Blueprint regular was found to be significantly more accurate than the two other alginates investigated, and had a degree of accuracy comparable with that of the more accurate elastomeric impression materials. Within this group of materials the inaccuracy varied between 39 and 130 microns. Generally, the addition-curing silicones were more accurate than the polyethers. Baysilex and President regular body had the highest degree of accuracy of the elastomeric impression materials.     

口内扫描仪临床扫描精度及影响因素把控

牙体缺损修复中,通过口内扫描获取数字化印模的技术以其简单、舒适、快捷的特点越来越多地被应用于临床。数字化印模的精度(包括正确度和精密度),是影响修复体密合性和修复最终成败的关键。各种口内扫描设备扫描原理不同,扫描精度有所不同。另外,临床操作中采取的扫描方案、预备体质量和口腔环境等因素都会影响到扫描精度。了解口内扫描原理和扫描精度相关影响因素,在临床操作中采取相应的应对策略可以提高扫描精度,最终提高牙体缺损数字化修复的成功率。     

An Evaluation of Dimensional Accuracy of One-Step and Two-Step Impression Technique Using Addition Silicone Impression Material: An In Vitro Study

The study is aimed to evaluate the dimensional accuracy, the effect of undercut of two different configurations and the elastic recovery of addition silicone impression material assessed indirectly, by measuring the dimensions on stone models recorded from the impression of the master model, using one-step and two-step impression technique, for addition silicone impression materials. Measurements are taken to evaluate horizontal or linear and vertical dimensional changes, of the abutment V and abutment C from the stainless steel model. Heavy body/light body material is used for making one-step impression technique in a custom tray. Putty/light body is used for taking two-step technique in a stock metal tray. Improved die stone is used for pouring the impression. The different 11 locations on the dies produced by two different techniques are measured microscopically on image analyzer and compared with those of stainless steel model. Anova test was applied to test the differences of mean values of inter and intra abutment measurements, to calculate p value. Unpaired t test was applied to calculate t value. Results showed less deviation of stone models produced by one-step technique from stainless steel model, whereas the deviation of stone models produced by two-step is comparatively more. (p < 0.01). This difference of deviation is significantly less in one-step as compared to two-step technique. One-step is sufficiently dimensionally accurate than two-step technique in conjunction with addition silicone impression material. They have the best elastic recovery from the two undercut configurations.