Dimensional stability of autopolymerizing acrylic resin impression trays

A study was undertaken to determine the optimal interval between fabrication of an autopolymerizing acrylic resin custom impression tray and making a final impression. Twenty mandibular arch-shaped trays, 10 each of Fastray and Formatray resin, were evaluated for dimensional change. Both materials behaved similarly. Cross-arch contraction of the borders of buccal flanges and unilateral expansion of the borders of buccal-to-lingual flanges were observed. These changes indicate distortion. Linear dimensional changes occurred throughout 6 hours, which suggests that any impression made in a methyl methacrylate acrylic resin custom impression tray should be poured as soon as is conveniently possible. Significant linear dimensional changes were observed for only 40 minutes from the initiation of tray fabrication. This study concludes that while an aged tray is preferred, it is acceptable to make an impression in an autopolymerizing resin custom impression tray after 40 minutes.     

The effect of custom tray material type and fabrication technique on tensile bond strength of impression material adhesive systems

The purpose of this investigation was to evaluate the tensile bond strengths of two impression material systems (polysulphide and polyvinyl siloxane) to two custom tray materials [autopolymerizing and visible light-cured (VLC) acrylic resin]. The effect of polymerizing the tray materials directly against wax spacer and tin foil was evaluated for each material. Polymerizing tray materials against tin foil significantly increased the bond strengths of polysulphide and polyvinyl siloxane impression materials to VLC and autopolymerizing acrylic resin tray materials. Polyvinyl siloxane VLC cured against tin foil combination produced the strongest bond. The VLC resin tray material generated greater bond strength than autopolymerizing acrylic resin when polymerized against tin foil.     

Modified custom tray

The use of a custom tray is highly desirable for accurate impression making in situations with multiple abutments. This article describes a modified custom tray fabrication method using autopolymerizing acrylic resin. The custom tray is fabricated by intraoral relining with autopolymerizing resin that is polymerized extraorally. The final impression is obtained during the same session after tray polymerization at 100 degrees C for 5 minutes. Relined areas are refined by trimming excess resin with burs of a known diameter to create a 2-mm clearance for the elastomer. For areas with subgingival finish lines, only 0.5 mm of resin is removed to direct the elastomer into the gingival sulcus. The procedure is time-saving because it reduces the need for a retraction cord and minimizes inaccuracies that would necessitate another impression.     

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. .     

Bond strength of three nonaqueous elastomeric impression materials to a light-activated resin tray.

The bonding of nonaqueous elastomeric impression materials to the impression tray is critical for an accurate impression; mechanical locks and adhesive materials are commonly used to enhance bonding. This study evaluated the bonding of three elastomeric materials to a light-polymerized resin tray. Roughening the tray surface prior to the application of an adhesive enhanced the bond.     

The Bond Strength of Different Tray Adhesives on Vinyl Polysiloxane to Two Tray Materials: An In Vitro Study

There has been no established chemical bonding between custom tray resin and the elastomeric impression materials without the use of manufacturer’s recommended specific tray adhesive. The present study was aimed to compare the bond strength of the manufacturer recommended tray adhesives with the universal tray adhesives using the medium body consistency vinyl polysiloxane (VPS) material and custom tray made of autopolymerising resin and visible light cure (VLC) resin. A total 90 cubicle specimens of autopolymerising resin and 90 specimens of VLC resin were tested for its tensile bond strength. Effectiveness of universal tray adhesive was compared with manufactured tray adhesive. Each of these specimens was then subjected to tensile load in hounsefield universal testing machine at a cross head speed of 5 mm/min and the results were compared and evaluated using one way analysis of variance and post hoc Tuckey’s test. Analysis of bond strength revealed that the universal tray adhesive showed better strength and was statiscally significant when compared to the manufacture supplied tray adhesive. Comparison between both the groups, VLC resin showed better bond strength as compared to autopolymerizing resin. Universal tray adhesive had better tensile bond strength than the manufacturers recommended tray adhesive with the medium body viscosity VPS impression material for both autopolymerising and VLC tray resin.     

The effect of tray selection on the accuracy of elastomeric impression materials

This study evaluated the accuracy of reproduction of stone casts made from impressions using different tray and impression materials. The tray materials used were an acrylic resin, a thermoplastic, and a plastic. The impression materials used were an additional silicone, a polyether, and a polysulfide. Impressions were made of a stainless steel master die that simulated crown preparations for a fixed partial denture and an acrylic resin model with cross-arch and anteroposterior landmarks in stainless steel that typify clinical intra-arch distances. Impressions of the fixed partial denture simulation were made with all three impression materials and all three tray types. Impressions of the cross-arch and anteroposterior landmarks were made by using all three tray types with only the addition reaction silicone impression material. Impressions were poured at 1 hour with a type IV dental stone. Data were analyzed by using ANOVA with a sample size of five. Results indicated that custom-made trays of acrylic resin and the thermoplastic material performed similarly regarding die accuracy and produced clinically acceptable casts. The stock plastic tray consistently produced casts with greater dimensional change than the two custom trays.     

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.     

Duplication of interim speech aid for definitive impression tray fabrication.

A wax tray is stable and easily relieved if overextended. Unusual tray undercuts or angles needed for the partial resection patient need not be eliminated before the impression procedure. Relief of these undercuts is necessary with acrylic resin trays to ensure separation from the final stone cast. Because the wax tray is separated easily from the prosthesis during the boil-out, it is not necessary to "burn" or grind acrylic resin from the framework. The tray shape is duplicated from the existing interim prosthesis on the nasopharyngeal and oropharyngeal side. An arbitrarily shaped acrylic resin tray may be grossly overextended and require time-consuming clinical adjustments. An underextended tray on the nasopharyngeal side will not carry or support the impression material around or through the residual soft palate remnant. A tray that closely approximates the final prosthesis will allow use of a tissue conditioner final impression without need for border molding (Fig. 2). Duplicating the oropharyngeal side of the interim speech aid duplicates the previously established plane that is compatible with the tongue. The author has used this technique successfully for eight total and five partial soft palate resections. A cleft palate speech aid prosthesis has also been made with this technique.     

托盘粘接剂对藻酸盐印模材料与三种不同材料托盘间粘接强度的影响

目的研究托盘粘接剂对藻酸盐印模材料与不同材料托盘间粘接强度的影响。方法选择自凝树脂、光固化树脂和不锈钢3种托盘材料,每种材料分2组,一组涂布粘接剂,另一组不涂布粘接剂作为对照,总计6组,每组8个试件。采用藻酸盐通用型粘接剂以及临床常用的藻酸盐印模材料,装置在万能测力仪上进行拉力测试,所得数据用SAS软件进行统计分析。结果研究结果显示所有托盘材料中,应用托盘粘接剂组具有更高的粘接强度（P〈0．01）。不同托盘材料对粘接强度的影响具有统计学意义（P〈0．01）。结论在托盘表面应用粘接剂能改善印模材料和托盘的粘接强度,涂布粘接剂前后不锈钢材料托盘的粘接强度均大于树脂。     

The bond strength of elastomer tray adhesives to thermoplastic and acrylic resin tray materials.

This study evaluated the bond strength of selected impression materials (Permlastic, Express, and Hydrosil) to a thermoplastic custom tray material as a function of drying time of the adhesive after application to a tray material. In addition, bond strengths of a polysulfide impression material to an acrylic resin tray material and to a thermoplastic tray material made directly against wax were evaluated. Bond strengths were obtained directly from values of applied load at failure and important conclusions were drawn.     

Comparing effects of tray treatment on the accuracy of dies

The effects of tray treatments on the accuracy of dies from addition silicone impressions were investigated. Tray treatments included custom acrylic resin tray with adhesive, perforated custom acrylic resin tray without adhesive, and perforated custom acrylic resin tray with adhesive. No appreciable differences were found in the complete crowns among the three tray treatments on the first pours. Significant statistical differences observed in the MOD and occlusal inlays were nonetheless of questionable clinical significance. Adhesives are advisable if the impressions are poured repeatedly, however, to minimize accidental separation of the impression from the tray. The second casts were less accurate with complete crowns and MOD inlays when perforated trays were used without adhesives.     

3D打印无牙颌个别托盘的初步研究

目的探讨3D打印无牙颌个别托盘较传统方法制作的个别托盘1是否能有效减少临床椅旁操作时间;2托盘印模面处理后与藻酸盐印模材间的固位强度比较和变化。方法 1选取全口义齿修复患者10例,上颌为A组,下颌为B组,记录3D打印法和传统方法(自凝丙烯酸树脂)制作个别托盘的椅旁工作时间;2测量3D打印托盘和传统托盘(光固化树脂和自凝丙烯酸树脂)的印模面3种情况下(以不处理、打孔和涂布托盘粘接剂)与藻酸盐印模材间的固位强度。结果 1A、B组3D打印法分别是34.37、28.19 min,传统法分别是64.95、63.94 min,3D打印无牙颌个别托盘的时间均显著少于传统法的时间(P<0.05);23D打印托盘表面涂粘接剂组固位强度为2.31 N/cm~2,为组内最佳(析因方差分析P<0.01)。结论 3D打印无牙颌个别托盘相对于传统方法可有效减少椅旁工作时间;与藻酸盐印模材间具有良好的固位强度,打孔及表面涂托盘粘接剂均可明显提高其固位强度,表面涂粘接剂效果更明显。     

托盘粘结剂对硅橡胶印模材料与托盘材料间粘结强度的影响

目的：研究托盘粘结剂对硅橡胶印模材料与不同托盘材料间粘结强度的影响。方法：分别选用GC和3M二种硅橡胶,托盘材料为不锈钢和自凝塑料,托盘粘结剂为GC和3M公司提供的专用粘结剂,进行交互使用,不涂粘结剂的作为对照组,共12组。各组均为6个样本。印模材料的调和按厂商说明进行,注入专门的测试装置中。等印模材料完全凝固后,把整个装置连接到万能测力仪上进行拉力测试,以5mm／min的速度拉伸直到粘附脱落。所得数据用SAS软件进行统计分析。结果：托盘粘结剂的使用能显著提高硅橡胶印模与托盘的粘结强度（P〈0．01）。在不使用托盘粘结剂时,不同托盘之间的粘接强度差异无统计学意义（P=0．1559）;且不同托盘材料与不同硅橡胶印模材料间无交互影响作用（P=0．8226）。无论使用哪种硅橡胶印模材料或哪种托盘材料,应用GC托盘粘结剂组的粘结强度均高于3M托盘粘结剂组（P〈0．01）。结论：临床取模过程中在托盘表面应用粘接剂能有效的改善硅橡胶印模材料和托盘的粘接强度,从而提高印模的精确性。不同厂家提供的专用粘结剂可交互使用。     

自制个别取模器颈缘取模技术精确度的研究

目的：对比个别取模器龈下取模技术与常用藻酸盐及硅橡胶取模方法的颈缘精度的差异。方法：在患口中用3种方法制取印模,灌模后分别在体视显微镜下测量代型标志点到龈沟底的距离。结果：个别取模器法的标志点到龈沟底的距离大于常用藻酸盐法,与硅橡胶法相比,其颊侧点到龈沟底的距离较大,但在近、远中标志点无差异。结论：使用个别取模器的取模效果优于常用藻酸盐方法,与硅橡胶取模技术相类似。     

Adhesive properties of several impression material systems: Part II.

The effect of saliva contamination on the tensile adhesive bond strengths of four impression adhesive systems, (1) polysulfide, (2) polyether, (3) polyvinylsiloxane, and (4) condensation silicone impression adhesive, was studied. Standard acrylic resin tray samples of 1-inch square surface were made. Tray surfaces were contaminated with saliva either before or after the application of tray adhesives. Tensile tests were performed with a Universal Load testing machine. The tensile adhesive bond strengths of contaminated tray surface and contaminated adhesive were compared with a group of control. Contamination of all impression adhesives resulted in significantly lower bond strength. Except for the polyvinylsiloxane and polysulfide impression adhesive systems, saliva contamination of tray material significantly decreased adhesive bond strengths. Impression trays should be tried in the mouth, rinsed, and dried before adhesive is applied.     

Adhesion of elastomeric impression materials to trays

summary The tensile and shear adhesive bond strengths of two addition cured silicones (Provil and Express) and a polyether (Impregum) impression material to brass, poly(methylmethacrylate) and visible light-cured (VLC) tray resin were determined. Adhesive application significantly increased the bond strength; Provil and Express adhered most strongly to brass; whilst the Impregum-VLC combination produced the strongest bond. Indeed, VLC resin generated greater adhesion than acrylic resin. Exchanging the adhesives specified for each silicone material generally resulted in higher bond strengths. No correlation was established between speed of separation of the test surfaces and bond strength. For optimum clinical performance, the impression material (adhesive) tray material giving the highest bond strength should be utilized.     

Clinical applications of visible light-cured resin in maxillofacial prosthetics. Part II: Tray material

As an alternative to autopolymerizing acrylic resin, visible light-cured resin for custom-made impression trays is advocated. This new system facilitates chairside tray fabrication for custom-made impressions and benefits maxillofacial prosthetic patients needing intraoral or extraoral prosthetic rehabilitation.     

Evaluation of accuracy of the wash impression technique to rebase and replace the resilient part of a soft-lined denture

The dimensional inaccuracies that might be introduced during a wash impression technique within a heat-cured acrylic resin tray lined with a silicone resilient denture base material were investigated with the use of an electronic digitizer. Casts were poured from impressions of a machined metal die using a light- and heavy-bodied addition silicone in the soft-lined tray and compared with casts poured from impressions made in a hard-based tray and with the master die itself. The dimensions of the casts poured from the heavy-bodied impression in the soft-lined trays were significantly different from those poured from impressions in the hard-based tray when compared with the metal die. Those produced from the light-bodied material showed no statistically significant dimensional difference.     

Properties of the tray adhesive of an addition polymerizing silicone to impression tray materials

Adhesive bond strength studies for the tray adhesive of an addition vinyl polysiloxane (President) impression material were conducted with an acrylic resin, chromium-plated brass, and plastic trays. Tensile and shear stress studies were performed on the Instron Universal testing machine. Acrylic resin specimens roughened with 80-grit silicon carbide paper exhibited appreciably higher bond strengths compared with different types of tray material and methods of surface preparation.