A technique for temporary acrylic resin coverage in functional occlusal relationsip

A technique for constructing temporary acrylic resin restorations has been described. A silicone putty is used as the impression material and for making the functional occlusal registration and mold to create a temporary acrylic resin restoration that is in occlusal harmony.     

Adhesive properties of several impression material systems: Part I.

The tensile adhesive bond strength of five impression adhesive systems was studied: polysulfide, polyether, polyvinylsiloxane, condensation silicone impression, and polyvinylsiloxane putty adhesive systems. Results showed no significant difference in adhesive bond strength to autopolymerizing acrylic resin between the former four impression materials studied. Polyether and medium-viscosity polyvinylsiloxane demonstrated significantly higher adhesive bond strength to polystyrene than either polysulfide or condensation silicone. The medium-viscosity polyvinylsiloxane impression material showed significantly higher adhesive bond strength to polystyrene than autopolymerizing acrylic resin whereas polysulfide and condensation silicone impression materials adhered significantly better to autopolymerizing acrylic resin than polystyrene. The polyvinylsiloxane putty did not adhere to its impression adhesive. Variation of the speed of tensile testing between 5 to 20 inches per minutes did not affect the adhesive bond strength of a polysulfide impression material.     

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.     

加聚型硅橡胶一次法、两次法印模三维精度研究

目的评价加聚型硅橡胶一次法、两次法印模的精确性。方法使用轻、重体成分的加聚型硅橡胶采用一次法和两次法分别制取同一实验主模具的人造石模型,用高精度数显游标卡尺测量主模型及人造石模型上各标志点的距离,对测量数据进行统计学分析。结果在横径、纵径上,一次法较二次法更为精确,其中二次法与原始模型数据虽具统计学差异,但变化率微小,两种方法垂直径变化率均较大,但仍在美国齿科协会(ADA)标准允许值内。结论加聚型硅橡胶弹性印模材料使用一次法、二次法印模技术均具理想的印模精度。     

Accuracy of addition silicones as a function of technique

Both addition and condensation silicones produced stone dies that were larger in diameter and shorter in height than the tooth preparation. For both materials, there was little change in the distance between stone die preparations compared with the standard. The most significant difference between types of silicone was that condensation silicones produced significantly shorter dies (-0.24% to -0.37%) than addition silicones (-0.08%). Among addition silicones, Cinch produced more than twice as much vertical change (-0.16%) than the other three products (-0.06%). Since castings made from a short die will not seat completely on the prepared tooth, these results support the use of three of the four addition silicones tested. The same accuracy of impressions was achieved for all techniques (that is, putty/wash, single mix, and double mix) when addition silicones were used, whereas the putty/wash technique produced the most accurate dies for the condensation silicones. The custom tray produced dies that were much more accurate in vertical dimensions (-0.03%) than the stock trays (-0.15% to -0.21%). Thus the custom tray is the impression tray of choice, even for addition silicones, which produce relatively little polymerization shrinkage and are dimensionally stable.     

Single Stage Silicone Border Molded Closed Mouth Impression Technique—Part II

Functioning of a complete denture depends to a great extent on the impression technique. Several impression techniques have been described in the literature since the turn of this century when Greene [Clinical courses in dental prothesis, 1916] brothers introduced the first scientific system of recording dental impression. Advocates of each technique have their own claim of superiority over the other. The introduction of elastomeric impression materials [Skinner and Cooper, J Am Dent Assoc 51:523-536, 1955] has made possible new techniques of recording impression for complete denture construction. These rubber like materials are of two types; one has a polysulfide base and is popularily known as polysulfide rubber (Thiokol and Mercaptan). The other variety has a silicone base known as silicone rubber or silicone elastomer. Silicone elastomers are available in four different consistencies; a thin easy flowing light bodied material,a creamy medium bodied material, a highly viscous heavy bodied material and a kneadable putty material. This paper describes an active closed mouth impression technique with one stage border molding using putty silicone material as a substitute for low fusing compound.     

A controlled putty-wash impression technique

A precise impression is imperative for the construction of an accurately fitting indirect cast restoration. The putty-wash technique is commonly used in making impressions with silicone elastomers. Errors in manipulation may lead to inaccurate impressions. A technique is presented ensuring exact reseating of the putty impression tray and creation of a uniform wash space, which are essential for accurate results.     

Dimensional accuracy of resultant casts made by a monophase, one-step and two-step, and a novel two-step putty/light-body impression technique: an in vitro study

STATEMENT OF PROBLEM: Dimensional accuracy when making impressions is crucial to the quality of fixed prosthodontic treatment, and the impression technique is a critical factor affecting this accuracy. PURPOSE: The purpose of this in vitro study was to compare the dimensional accuracy of a monophase, 1- and 2-step putty/light-body, and a novel 2-step injection impression technique. MATERIAL AND METHODS: A stainless steel model with 2 abutment preparations was fabricated, and impressions were made 15 times with each technique. All impressions were made with an addition-reaction silicone impression material (Aquasil) and a stock perforated metal tray. The monophase impressions were made with regular body material. The 1-step putty/light-body impressions were made with simultaneous use of putty and light-body materials. The 2-step putty/light-body impressions were made with 2-mm-thick resin-prefabricated copings. The 2-step injection impressions were made with simultaneous use of putty and light-body materials. In this injection technique, after removing the preliminary impression, a hole was made through the polymerized material at each abutment edge, to coincide with holes present in the stock trays. Extra-light-body material was then added to the preliminary impression and further injected through the hole after reinsertion of the preliminary impression on the stainless steel model. The accuracy of the 4 different impression techniques was assessed by measuring 3 dimensions (intra- and interabutment) (5-mum accuracy) on stone casts poured from the impressions of the stainless steel model. The data were analyzed by 1-way ANOVA and Student-Newman-Keuls test (alpha=.05). RESULTS: The stone dies obtained with all the techniques had significantly larger dimensions as compared to those of the stainless steel model (P<.01). The order for highest to lowest deviation from the stainless steel model was: monophase, 1-step putty/light body, 2-step putty/light body, and 2-step injection. Significant differences among all of the groups for both absolute dimensions of the stone dies, and their percent deviations from the stainless steel model (P<.01), were noted. CONCLUSIONS: The 2-step putty/light-body and 2-step injection techniques were the most dimensionally accurate impression methods in terms of resultant casts.     

Dimensional accuracy of dental casts: Influence of tray material, impression material, and time

PURPOSE: This study evaluated the influence on dimensional accuracy of dental casts made with different types of trays and impression materials and poured at different and multiple times. MATERIALS AND METHODS: Two types of stock trays (plastic stock tray, perforated metal stock tray) and 4 types of custom tray materials (autopolymerizing acrylic resin, thermoplastic resin, and 2 types of light-polymerized acrylic resins) were used with 2 types of impression materials (addition polymerizing silicone and polyether), to make impressions of a metal master model. Each tray and impression material was used to make 5 impressions. Casts were made by multiple pourings at 30 minutes, 6 hours, 24 hours, and 30 days after impression making. Using a measuring microscope, 12 distances were calculated based on measurements of 8 reference points. The absolute value of the difference of each measurement was calculated, as was the corresponding measurement on the master model. A Bayesian model using a simple noninformative prior was used to analyze these data. RESULTS: Statistical differences within 6 microm were found only with thermoplastic resin tray material for addition silicone, and for thermoplastic resin tray material and 1 type of light-polymerized acrylic resin for polyether. Neither stock trays nor custom trays contributed to the differences in accuracy of the casts. All deviations in casts made with silicone impression material were within a clinically acceptable range. For the polyether, distortions occurred that were clinically unacceptable. Impressions made from polyether distorted over time. Silicone impression material has dimensional stability up to 30 days. CONCLUSION: Accurate casts can be made with either stock trays or custom trays. An impression made from polyether should be poured only once and within 24 hours after impression making, because of the distortion of the material over time. Silicone impression material has better dimensional stability than polyether. .     

A clinical pilot study of the dimensional accuracy of double-arch and complete-arch impressions

STATEMENT OF PROBLEM: It has been suggested that articulated casts fabricated with the double-arch impression technique may have superior occlusal accuracy than those fabricated with a single complete-arch impression. However, lack of tray rigidity may lead to flexure of the impression/tray complex, resulting in inaccurate dies in the bucco-lingual dimension. PURPOSE: This clinical pilot study compared the dimensions of dies fabricated with 3 types of double-arch impressions to dies fabricated with the conventional complete-arch, custom tray method. MATERIAL AND METHODS: Thirty-five addition silicone impressions were made of cast metal copings cemented onto natural teeth prepared as complete-crown abutments. Four combinations of tray types and impression material viscosity were used: (1) complete-arch, custom acrylic trays loaded with heavy-bodied material; (2) double-arch, disposable plastic trays loaded with heavy-bodied material; (3) double-arch, disposable plastic trays loaded with putty material; and (4) double-arch, reusable brass metal trays loaded with heavy-bodied material. Immediately prior to tray insertion, light-bodied impression material was syringed over all copings as a wash. The 4 copings were fabricated from cast gold and simulated metal-ceramic complete-crown thimbles with polished collars and had "projections" on the occlusal surfaces. The impressions were poured in type IV die-stone. Bucco-lingual and inter-abutment dimensions were measured. The differences between the stone dimensions and cast metal control dimensions were calculated and converted to percent dimensional change. The data were analyzed with 1-way analysis of variance, Student t tests, and Mann-Whitney tests (P<.05). RESULTS: The plastic double-arch tray loaded with heavy-viscosity addition silicone and a low-viscosity wash produced the least accurate combination inter- and intra-abutment dimensions. For this protocol, 1.17% mean dimensional change was recorded. This result was significantly different than that obtained for the other 3 impression methods tested. No significant differences were found between the complete-arch method and protocols in which putty was loaded in a plastic or metal tray. CONCLUSION: Within the limitations of this pilot study, the more rigid tray/impression material combinations more accurately replicated stone dies.     

Effect of impression technique and multiple pours on accuracy of stone models.

The number of accurate repour models obtainable from a single impression is of clinical importance. This study was designed to compare the accuracy of initial and repour models obtained from an impression recorded in a hydrophilic addition curing silicone and to determine whether or not this accuracy is affected by the impression technique employed and whether any interaction between impression techniques and levels of pour existed. The laminated and putty wash plus spacer techniques were employed. Six impressions were recorded of a brass master model with each technique. Improved stone models were poured after 2 hours and then repoured in the same impression at 3, 4, 5 and 6 hours. Thus, 30 models were poured with each impression technique. Using a reflex microscope, measurements between two fixed points on the brass model were taken and compared with similar measurements obtained from the stone models. The analysis of variance indicates that no significant difference exists between impression techniques (p greater than 0.05) and between the first pour and first repour model (p greater than 0.05). With the material tested, this study indicates that the laminated and putty wash plus spacer techniques both give accurate impressions and that only two accurate models can be poured.     

Effects of reheating on the accuracy of addition silicone putty-wash impressions

The effect of the relatively high thermal contraction of addition silicones (polyvinylsiloxane) on the accuracy of stone casts was evaluated using the putty/wash relining impression technique and acrylic resin trays. Impressions were made at 37 degrees C and were divided into two groups. One group was poured at room temperature (22 degrees +/- 2 degrees C) and another group was reheated to 37 degrees C before pouring. Measurement of the dimensional changes failed to reveal improved accuracy of the stone casts poured at the same temperature as that reached during impression making. On the basis of this limited sample, it can be concluded that reheating the impression using the putty/wash relining technique did not improve the accuracy of the stone cast.     

An impression technique for implant-retained orbital prostheses

This article describes an impression technique for an implant-retained orbital prosthesis; in this situation, making the implant impressions in the conventional manner was not possible due to improper implant positioning. An advantage of this technique is that the acrylic resin transfer device that incorporates magnets is also used as the acrylic resin substructure for the silicone orbital prostheses. A disadvantage of the procedure is the requirement of an additional appointment to make the definitive impression. The effect of acrylic resin polymerization shrinkage is minimized by prefabricating the acrylic resin substructure that is used to splint magnets and corrected at the time that the definitive impression is made.     

Accuracy of three polyvinyl siloxane putty-wash impression techniques

STATEMENT OF PROBLEM. There is much discussion in the dental literature concerning the effect of the impression technique on the accuracy of cast restorations. PURPOSE. This study assessed the accuracy of 3 putty-wash impression techniques using the same impression material (polyvinyl siloxane) in a laboratory model. MATERIAL AND METHODS. The 3 putty-wash impression techniques used were (1) 1-step (putty and wash impression materials used simultaneously); (2) 2-step with 2-mm relief (putty first as a preliminary impression to create 2-mm wash space with prefabricated copings. In the second step, the wash stage was carried out); and (3) 2-step technique with a polyethylene spacer (plastic spacer used with the putty impression first and then the wash stage). For each technique, 15 impressions were made of a stainless steel master model that contained 3 complete crown abutment preparations, which were used as the positive control. Accuracy was assessed by measuring 6 dimensions (intraabutment and interabutment) on stone dies poured from impressions of the master model. RESULTS. One-way analysis of variance showed statistically significant differences among the 3 putty-wash impression techniques, for all intraabutment and interabutment measurements (P <.001). Overall discrepancies of the 2-step technique with 2-mm relief putty-wash impression technique were significantly smaller than that in the 1-step and polyethylene putty-wash impression techniques. CONCLUSION. The polyvinyl siloxane 2-step, 2-mm, relief putty-wash impression technique was the most accurate for fabricating stone dies.     

Preparation of feeding obturators for newborns with cleft palate: clinical and laboratory procedures

The clinical and laboratory procedures for fabricating a neonatal feeding obturator requiring only a single impression followed by relining of the plate are described. The technique involves the use of a specific custom tray and polysiloxane putty for the impression, autopolymerizing acrylic resin for the plate, and a soft liner for the relining procedure. In over a decade, an obturator plate applied with this technique in 81 newborns with cleft palate has obtained good nutritional and functional results.     

ZA-1偶联剂对赝复硅橡胶与丙烯酸树脂材料粘接强度的影响

目的：研究ZA-1偶联剂在两种加成型硅橡胶及两种丙烯酸树脂之间交叉使用时粘接强度的影响。方法：选择ZY—1硅橡胶与A-2186硅橡胶分别与临床中常用的热凝丙烯酸树脂和自凝型树脂制成硅橡胶一偶联剂一丙烯酸树脂粘接试件,分别测试试件粘接强度。选择ZY-1组进行热氧老化试验。结果：四组硅橡胶偶联剂粘接系统中,ZY-1硅橡胶与丙烯酸树脂的粘接强度显著高于A-2186组（P〈0．05）。热凝和自凝丙烯酸树脂对粘接系统的粘接强度无显著影响。所有实验组的破坏方式均为内聚破坏。热氧老化处理后ZY-1丙烯酸树脂粘接试件的粘接强度与未老化组相比有显著性提高。结论：丙烯酸树脂材料的种类对粘接强度的影响不大。两种不同的加成型硅橡胶与ZA-1偶联剂交叉使用时粘接强度略有下降,但粘接效果不影响临床使用。热氧加速老化实验使ZY-1加成型硅橡胶与丙烯酸树脂的粘接强度有所提高。     

加载载荷对钛锆铌锡合金摩擦磨损性能的影响

目的:探讨载荷变化对钛锆铌锡合金与滑石瓷对磨时摩擦磨损性能的影响.方法:使用MMV-1立式万能摩擦磨损试验机,以滑石瓷为对磨物,载荷设置为20、50、100 N,在37℃人工唾液润滑的试验工况下,对口腔修复用钛锆铌锡合金进行二体摩擦磨损试验.采用扫描电镜观察表面磨损形貌,电子天平得出磨损量.结果:钛锆铌锡合金与对磨物滑石瓷的磨损量随载荷的增加而增大.载荷20N,钛锆铌锡合金的磨损机制主要为磨粒磨损; 50N时,磨损机制是粘着磨损伴发磨粒磨损;100N时,钛锆铌锡合金磨损机制以粘着磨损为主.结论:载荷增加可增大钛锆铌锡合金的磨损量,导致磨损机制改变,在高载荷条件下可发生严重粘着磨损,缩短修复体的使用寿命.     

Force versus time profiles of selected heat-processed denture liners.

The potential correlation of the force versus time behavior of four resilient lining materials and their acceptance by patients was investigated. Two modified acrylic resins and two silicone denture lining materials were tested. The response of the soft lining materials to a programmed indentation test was used to define a parameter for each denture liner product. A parameter defined as the "Rebound Index," using force-time data obtained from the indentation measurements, was significantly different for the modified acrylic resins compared to the silicone materials. Improved patient acceptance was correlated with higher values of this index.     

Fine detail reproduction of very high viscosity poly(vinyl siloxane) impression materials

Very high viscosity (putty) poly(vinyl siloxane) impression materials are used with both the conventional double-mix and single-mix putty/wash techniques. When the latter technique is used, portions of the impression of the prepared teeth may be made in the putty rather than the wash material. This study investigated the ability of ten different putty materials to reproduce fine detail. The American Dental Association stainless steel test die for Specification No. 19 was used. Two of the materials consistently reproduced the 20-microns groove. Three of the materials reproduced the 20-microns groove in one-half of the samples tested, while the remainder failed to do so.     

Working Times and Dimensional Accuracy of the One-Step Putty/Wash Impression Technique

PURPOSE: Using the one-step polyvinyl siloxane impression technique, this study compared the effect of putty material working time on the dimensional accuracy of recovered improved stone casts. MATERIALS AND METHODS: An acrylic resin master cast was fabricated with embedded reference points to enable both horizontal and vertical measurements. Four commercially available polyvinyl siloxane impression putties with light body washes were evaluated: 1) Extrude (Kerr), 2) Cutter (Coltere), 3) Express (3M), and 4) Reprosil (Caulk). Each putty was mixed by hand for 30 seconds, placed in a plastic stock tray, and seated on the master cast at 0, 30, 60, 90, and 120 seconds after mixing (N = 100, n = 5). The impressions were poured in improved stone, and vertical and horizontal measurements were made to 0.001 mm between reference points on recovered casts using an optical traveling microscope. ANOVA (p < or = .05) was used to compare vertical and horizontal measurements to master cast dimensions. RESULTS: No statistically significant difference was found among casts for all materials and time periods tested. When horizontal measurement ranges were evaluated, Extrude casts exhibited the widest range of measurement, especially when the trays were seated at 90 and 120 seconds. When vertical measurement ranges were evaluated, Express casts at 120 seconds exhibited the widest range. CONCLUSIONS: A high range of variability in vertical and horizontal dimensions occurred at the later time periods, especially for Extrude and Express casts. As a result of rapid polymerization and poor flow properties of putty materials, the impression tray should be seated within 60 seconds after putty mixing to reduce dimensional variability of recovered casts.