Condensation Silicone Research Articles

Survey of Impression Materials and Techniques Used in Fixed Prosthodontics among Nepalese Dentists

There is variation in fixed prosthodontics practice and many studies have concluded that clinicians definitely deviate from the recommended clinical protocols. If this happens during treatment with fixed prosthesis, the quality of fixed prostheses is compromised which affects it’s long term survival. Therefore, the aim of this study was to evaluate the use of impression materials and techniques in fixed prosthodontics among Nepalese dentists and to compare the findings on the basis of educational level and years of experience. A cross-sectional, questionnaire-based online survey was done amongst the Nepalese Dentists through google forms. Data from the completed questionnaires were analysed using the SPSS version 16. All statistical analyses were carried out at a significance level of P < 0.05. Out of 129 participants, 68 (52.7%) dentists often made diagnostic impression for fabrication of study cast. 85(65.9%) dentists used Addition silicone, 11(8.5%) used Condensation silicone and 33(25.6%) used Alginate for final impression making. Most commonly used elastomeric impression technique was Putty Wash single stage (56.2%), 40.7% used Putty Wash two stage, 3.1% used Single mix (Monophase) technique. Regarding retraction cord, 63.5% of dentists used Plain gingival retraction cord and 35.7% of dentists used Chemical impregnated retraction cord. Conclusion: The study found that most of the responses on use of impression materials and techniques were significantly associated with the level of education and clinical experience.

Comparison of Dimensional Accuracy of Three Different Impression Materials Using Three Different Techniques for Implant Impressions: An In Vitro Study

To compare the dimensional accuracy of polyether, polyvinyl siloxane, and polyether polyvinyl siloxane hybrid impression materials using closed tray, open tray splinted, and open tray nonsplinted coping impression techniques and to find out the best suitable impression material and technique combination for implant impressions. The sample size of the study was 45. The combinations of materials and techniques were divided into nine groups, namely polyvinyl siloxane with closed tray, polyvinyl siloxane with open tray nonsplinted copings, polyvinyl siloxane with open tray splinted copings, polyether with closed tray, polyether with open tray nonsplinted copings, polyether with open tray splinted copings, polyvinyl siloxane-polyether hybrid with closed tray, polyvinyl siloxane-polyether hybrid with open tray nonsplinted copings, and polyvinyl siloxanepolyether hybrid with open tray splinted copings. Five samples of each group were evaluated. A total of 45 impressions were taken. A stainless steel master metal framework with three internal hex implants was fabricated and used to generate the samples. A common condensation silicone putty spacer was applied over the impression copings attached to the implants, which was then duplicated. All trays were fabricated on this duplicated silicone die using light cure acrylic resin. Trays to be used for open tray techniques had their top removed for gaining access to screws of the impression copings. Splinting of coping for OS group was done using pattern resin. Impressions were poured, and master cast was generated. Interimplant distance was measured using stereomicroscope and an image analyzing software. Open nonsplinted technique resulted in significantly better replication of implant positions compared to open splinted and closed techniques. Hybrid impression material depicted significantly better dimensional accuracy than polyether and polyvinyl siloxane. Hybrid open nonsplinted depicted least mean difference in interimplant distance, followed by hybrid open splinted and polyether open splinted groups. Polyvinyl siloxane closed tray showed maximum difference in interimplant distance in comparison with other groups. Polyvinyl siloxane-polyether hybrid impression material and open nonsplinted technique gave best replication of implant positions on the master cast. Accuracy of impressions and casts is of great importance for the fabrication and long-term clinical success of precisely fitting implant-retained prostheses.

Implant Impression Making: Take-Off Guide for Beginners

AbstractDental implants are fixtures that constitute for the replacements of the root of a missing natural tooth. Dental implant therapy has been widely used for the restoration of partially and fully edentulous patients. The implant literature emphasizes the importance of a passively fitting prosthesis to prevent prosthodontic complications or even loss of fixture integration. Failure to achieve a passively fitting prosthesis and force tightening of superstructure may result in complications such as abutment, framework, and gold screw loosening or fracture. Various materials that can be used for making an implant impression are polyether, polyvinylsiloxane, condensation silicone, polysulfide, irreversible hydrocolloid material, and various others. There are various studies in relation to the accuracy of these impression materials out of which various scientists concluded different results with most studies stating polyether with the maximum amount of dimensional accuracy in comparison to other materials. An accurate implant impression plays a significant role and serves as a starting point in the process of producing good working casts. Thus, the accuracy of impression techniques becomes a significant issue in consideration of passive fit. Reproduction of intraoral relationship of implants through impression procedures is the first step in achieving accurate fit prosthesis. This transference is still complicated by the number, angulation, depth, and position of implants. The advent of computer-aided design/computer-assisted manufacturing technology improved the framework fabrication procedures and has increased the precision of fit of implant prosthesis.

Comparing the Dimensional Accuracy of Casts Obtained from Two Types of Silicone Impression Materials in Different Impression Techniques and Frequent Times of Cast Preparation.

Introduction The dimensional accuracy of casts is essential in the quality of fixed prosthesis treatment, whereby the impression method is a very crucial factor affecting it. The aim of this in vitro study is to compare the dimensional accuracy of casts resulting from two types of silicone impression materials in different impression techniques and frequent times of cast preparation. Materials and Methods A metal model was made from two prepared abutments, and 10 casts were prepared from each material technique (n = 40). The impressions were made by condensation and addition silicone (one-stage and two-stage impressions). The casts were made from same impressions 1 h, 24 h, and 14 days. The diameter, height, and the distance between two dies were recorded. Data were analyzed by repeated measure ANOVA (P value <0.05). Results The dimensional accuracy of all four materials techniques of impression (diameter, height, and the distance between dies) was the same in different times of impression. Dimensional accuracy of the die diameter and distance between dies in one-stage (Speedex) condensation silicon and one-stage (Panasil) addition silicone did not differ significantly, and their one-stage method developed more accurate casts compared to the two-stage method of the same impression material. The height of the casts prepared from the one-stage method through Speedex and Panasil did not differ significantly from the two-stage method of the same impression material. Conclusion One-stage condensation silicone and one-stage addition silicone material techniques offered the maximum dimensional accuracy in the obtained casts. The time of impression did not have any significant effect in the accuracy of any of the four impression material techniques.

Comparison of dimensional accuracy of elastomeric impression materials using 3D laser scanner

BackgroundThe dimensional accuracy of elastomeric impression materials has been evaluated by different methods but their reliability is still questionable. The aim of this study was to evaluate the dimensional accuracy of elastomeric impression material using 3D laser scanner. MethodIn the present study, a metal die with its custom tray were designed. Using this die and tray, 10 impressions each were made from addition silicone (Aquasil LV; Dentsply), condensation silicone (Speedex coltene, Whaledent) and polyether (3M; ESPE). All the impressions were poured with Type IV die stone and total of 30 die replicas were obtained. These were scanned with a Picza 3D laser scanner (LPX 600, Roland,California) and the difference between the stone model was calculated by determining its volumetric changes using CAD-CAM pero version 2.0. One way analysis of variance (ANOVA) was used to compare the groups, whereas significance of mean difference between the groups was done by Tukey HSD. ResultsAll the three groups showed mean decrease indicating a dimensional shrinkage from the master die. Mean percentage dimensional change in condensation silicone was maximum (-319.02 ±15.50) followed by polyether (-122.59 ± 0.64) and least in addition silicone (-23.83 ± 0.43). All the results were statistically significant (p<0.001). ConclusionPicza 3D laser scanner can precisely measure the volumetric changes in all the three elastomeric impression materials.

Use of silicones in fixed aesthetic rehabilitations: clinical case

Molding in a fixed prosthesis is one of the most important stages in rehabilitative treatment, as it is there that attempts are made to reproduce dental preparations and adjoining regions by using appropriate materials and techniques. Among the fixed prosthesis molding materials available on the market, the elastomers stand out, which are polymers where the prey occurs through the increase of the chain and the establishment of cross-links. The objective of the study is to present a clinical case and perform a literature review on the use of condensation silicone and addition to molds in Fixed Prosthesis. In this literature review, a survey of PubMed, Scielo and Lilacs data was performed, using the descriptors: Denture, Partial, Fixed; Dental Impression Materials and Elastomers. It is possible to conclude that in the field of Dentistry, the elastomers, among them the condensation-cured and addition-cured silicones, both provide high precision models and are the most used materials in works with fixed partial dentures. Therefore, it is up to the professional to know the properties and adapt to the best group of chosen materials.

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Dimensional accuracy of three impression materials by one-step and two-step impression techniques: An in vitro study

Introduction: An accurate impression is essential to create a well-fitted dental prosthesis. This study aimed to compare the dimensional accuracy of three elastomeric materials using one-step and two-step impression techniques. Methods: In this study, 20 impressions were fabricated for each Vinyl siloxane ether (Identium), condensation silicone (Speedex), and additional silicone (Panasil) impression materials by the one-step and two-step impression techniques using perforated metal trays. The one-step impression technique was simultaneously performed with heavy body/light-body materials. In the two-step impression technique, acrylic copings with 2-mm thickness were placed on the abutments to obtain similar spacing for the light-body material. The dimensional accuracy of different impression materials and techniques were measured using distance differences of the stone dies from the master cast; subsequently, the results were compared with the reference model. Data were analyzed using a one-way analysis of variance and Dunnett’s tests (α=0.05). Results: All impression materials demonstrated an acceptable clinical accuracy. Identium (Vinyl siloxane ether) displayed the most accuracy in both the one-step and two-step impression techniques (P>0.05). The best accuracy for Panasil (additional silicone) was found to be the two-step impression technique (P>0.05), and the best accuracy for Speedex (condensation silicone) was reported as the one-step impression technique (P>0.05). Furthermore, the one-step impression technique was highly accurate in diameter dimension, as compared to the two-step impression technique. Conclusion: As evidenced by the results, the accuracy of impression is affected by the impression materials. Moreover, Identium (Vinyl siloxane ether) demonstrated the most accuracy in both one-step and two-step impression techniques.

Dimensional change of impression materials for dental prothesis using different measuring methods

The aim of this study was to verify the effectiveness of alternative techniques for measuring the linear dimensional change of molds obtained by different impression materials. A stainless-steel die containing three lines was used to get the impressions. The impression materials were handled according to the manufacturers' instructions. After gelation/polymerization time, the molds (n=12) were stored for 30 minutes and the lines were subsequently measured using: a microscope (Olympus Measuring Microscope STM; Olympus Optical Co) with a 30x magnification (MM, control group), a digital caliper (Mitutoyo Digimatic; Kawasaki) (DC) and digitization using a digital camera (Canon EOS Rebel 3Ti; Canon) (DI). For each mold, a mean of the length of the lines was obtained. For each impression material, the difference in the length between the metallic matrix and the mold was considered as linear dimensional change (%). The data were submitted to the non-parametric Kolmogorov-Smirnov test, followed by one-way Analysis of Variance (ANOVA) for each material, and the means were compared by the Tukey test (α=0.05). The DI group promoted values of dimensional accuracy without significant differences with the control group (MM), except for the putty-body condensation silicone. The DC group showed significant differences for MM and DI groups for all impression materials tested. The DI group showed to be a reliable methodology (Standard error of the mean <10%) to measure the linear dimensional change of all impression materials. The DI group presented molds with linear dimensional change values without significant differences with MM group, except for the putty-body addition silicone. The digitization is a reliable methodology to evaluate the linear dimensional changes of molds made with impression materials, except for the putty-body elastomeric impression materials.

Evaluation of reproduction technique of bitemarks printed in chewing gum for human identification

Forensic Odontology is the science that correlates dental and legal principles, used for processes such as human identification. One of the possible acting fields for Forensic Odontologists is the analysis and study of patterns and injuries created by human bite marks. This study aimed to show the applicability of dental marks printed in chewing gum for human identification in forensic investigations. A transversal observational study was carried out. The data was collected from 20 volunteers over 18 years old. Each subject had their upper and lower dental casts and was asked to chew a piece of gum for one minute. The pieces of chewing gum were refrigerated at -20ºC for a week, and reproduced with addition and condensation silicones using an adapted reproduction technique. The analysis of the chewing gum was made by overlays. The ANOVA test showed no significant differences on width and length between the pieces of chewing gum and their reproductions (greatest width p=0.918, and the length p=0.981). The analysis of the reproductions with plaster mold showed that there was no difference when using addition silicone or condensation silicone. During the analysis, various suspects could be excluded from the investigation (up to 11, depending on the technique used), but it was not possible to confirm one of them as the main suspect. The study showed that the reproduction technique of chewing gum is efficient, viable and easily performed; and can be used in cases of human identification in forensic investigations. However, it is necessary to certify that the chewing gum effectively presents a bite mark and that it is correctly handled to avoid alterations. It also became evident that the process of refrigeration is essential for the analysis proposed in this study.

Evaluación del efecto de diferentes combinaciones de materiales de impresión y vertido en la adaptación marginal e interna de las coronas de circonio

Purpose: Two important factors in dental prosthesis are making an accurate impression and producing a suitable cast which represents the exact relationship between prepared tooth and oral structures. This study, aimed to investigate the effects of different combinations of impression and pouring materials on marginal and internal adaptation of premolar zirconia crowns. Material and Methods: Forty maxillary premolars were prepared considering round shoulder finish line. The impressions were made either by additional (Panasil) or condensation (Speedex) silicon, and poured by two different types of gypsum materials (Siladent or GC gypsum) (N=10). Zirconia crowns were fabricated using a CAD-CAM system. The crowns were cemented, and the samples were cut in bucco-lingual direction. Marginal and internal gaps were measured by stereomicroscope (×25). Results: The mean marginal gaps for Pansil-Siladent, Panasil-GC, Speedex-Siladent, and Speedex-GC were 141 μm, 143 μm, 131 μm, and 137 μm respectively. The internal gaps were 334 μm, 292 μm, 278 μm, and 257 μm respectively. The independent T-Student test showed no significant differences in average marginal or internal gap among various impression and gypsum materials or their interactions (p&gt;0.05). Two-way ANOVA test showed no significant differences in maximum marginal or internal gap among various impression and gypsum materials and their interactions (p&gt;0.05). Conclusion: The present study revealed no statistically significant difference in marginal/internal gap among crowns prepared using different combinations of impression-pouring materials evaluated.

Comparative Analysis of the Effect of Border Molding Using Different Molding and Final Impression Materials on the Retention of Complete Denture Bases

Aim : It is for comparing the retention of complete denture bases made by border molding using the low fusing compound and putty type condensation silicon by using metallic zinc- oxide eugenol and medium body condensation silicon as final impression material.. Subjects and Methods: the study was carried out on 20 patients , the selected was completely edentulous with well-developed ridge four dentures for each patient was fabricated :( Group A):border molding with green stick compound and final impression with zinc oxide eugenol(Group B): border molding with green stick compound and medium body rubber base as a final impression(Group C): border molding with putty type and medium body condensation silicon as a final impression materials(Group D): border molding with putty type condensation silicon and medium body rubber base as a final impression. Results: Statistically significant results were in complete denture obtained from putty type border molding and medium body condensation silicon final impression, while the least values obtained from green stick border molding and zinc oxide eugenol final impression. Conclusion: Based on the favourable results of this study , it can summarized that the complete denture obtained from putty type and medium body condensation silicone more retentive than other complete dentures obtained from other border molding and final impression materials.

Antibacterial effects of barium titanate reinforced polyvinyl-siloxane scaffolds

Polyvinyl-siloxane (PVS) is a modified condensation silicon that has found applications in the field of dental impression materials thanks to its high biocompatibility and the ability to be modeled on solid surfaces with a micrometric resolution. Major concerns have been raised on the possibility to sterilize PVS without distorting its geometrical shape, as immersion in antibacterial solutions often results in swelling. As a possible alternative, both radiofrequency glow discharge and UV sterilization have been successfully applied. In this paper, we focus on the possible use of a cheap, bio-compatible ceramic reinforcement powder (BaTiO3) to obtain a higher resistance to colonization and contribute to the prevention of bacterial infections, not only for temporary applications but also long-term. We also use a vacuum treatment to transform the composite polymer into soft scaffolds with relative densities between 35 and 65%) with similar biological properties. Testing with fractions of ceramic reinforcement up to 25% has clearly shown a beneficial effect in terms of bacteria viability against Staphylococcus epidermidis, with potential for future applications as soft biomedical scaffolds, medical clothing, sanitary materials, and filters for the sterilization of air and water.

Comparison and Evaluation of Linear Dimensional Accuracy of Three Elastomeric Impression Materials at Different Time Intervals Using Vision Inspection System: An In Vitro Study.

ABSTRACTBackground:Making an impression represents a crucial step in fabrication of a prosthesis. Elastomers are the most commonly used materials for precise and accurate recording and reproduction of tooth morphology and surrounding soft tissue.Aims and Objective:The aim of this study was to compare and evaluate the linear dimensional accuracy of three elastomeric impression materials: addition silicone, condensation silicone, and polyether at different time intervals up to 15 days using a vision inspection system.Materials and Methods:Dimensional accuracy of impression materials was measured at certain designated time periods using stainless steel die. The impressions of die were made using one representative material of each type of elastomeric impression material. The die along with the impression material in the mold was held using a clamp and put in a water bath maintained at mouth temperature. The linear dimensional changes taking place in each material with time were measured using the vision inspection system.Results:On comparison with master die impression at 30min, 1h, and 1½ h time interval, a significant decreased mean dimension of condensation silicone was observed, whereas addition silicone and polyether showed statistically nonsignificant difference. At 2, 3, 4, and 12h time span, a significant difference in mean dimension of addition and condensation silicone was noted, whereas polyether showed a nonsignificant difference. At 24h, 1 week, and 15 days duration, on comparison with the master die, a significant reduction in mean dimension of condensation silicone was discovered, whereas addition silicone and polyether showed nonsignificant difference.Conclusion:Polyether showed significantly lesser dimensional changes among all three materials, though the differences were small enough to be considered clinically acceptable.

Diastema closure and papillary induction technique with additions in composite resin: case report

Diastemas happen due to several factors, among them, discrepancy in the size of the teeth and abnormal insertion of the labial frenum. These changes directly affect the harmony of the smile, generating aesthetic dissatisfaction. This article aims to discuss the direct technique of closing diastemas and papillary induction as a way to prevent the formation of dark triangles. Young patient, 22 years old, female, student, sought care at the Faculty of Dentistry of the Federal University of Para, reporting dissatisfaction with her smile, caused by the space present between the upper central incisors. Anamnesis, clinical assessment intra and extra oral, intra oral photos, periapical radiography and distance measurement between the distal faces element 11 and 21 to determine the ideal midline, the case continued with the molding of the arches with irreversible hydrocolloid and obtaining the plaster model, diagnostic waxing, guide with condensation silicone, selection of composite resins Trans-N and A2 restoration, photoactivation using the blue photoactivator LED with light intensity of 1,100mW / cm2 / 15 seconds, and a wavelength of 420 -480nm. The contact point was adequate, while the restoration was made, there were additions in the cervical region of the teeth to change the papillary contour. In the finishing, abrasive strips and a sequence of diamond polishing tips 2135F and 2135FF were used and in the Enhance System polishing, a sequence of medium and fine grained sanding discs and felt discs with polishing paste, achieving adequate aesthetics and function as well as satisfaction of the patient.

Marginal adaptation of provisional crowns made of acrylic and bisacrylic resins using different impression materials

Aim: To evaluate the marginal adaptation of provisional crowns made of acrylic and bisacrylic resins using different impression materials. Methods: a metal die and a matrix applied through a direct technique were used to fabricate the specimens. The impression materials used as a matrix were divided into four groups: Irreversible hydrocolloid (IH), laboratory silicone (LS), condensation silicone (CS), and addition silicone (AS). After the impression procedures, each matrix was loaded with the provisional prosthetic materials, Alike, Duralay, Protemp 4, and Structur 3 (n = 12). Marginal discrepancy was evaluated using a stereomicroscope at ×45 magnification. The images obtained were transferred to the Corel Draw X7 program, and the distances from the cervical margins of the specimen to the reference lines at the metal die were measured vertically. The data were analyzed by using 2-way ANOVA followed by the Tukey test (α=.05). Results: the acrylic resins had higher values ​​of marginal discrepancy compared to the bisacrylic resins. A statistically significant difference was found between all impression materials, and the irreversible hydrocolloid presented higher values of discrepancy (303.28–613.31 μm), whereas addition silicone had the lowest (48.61–190.06 μm). Conclusions: the bisacrylic resins had a better marginal adaptation compared to the acrylic resins. The addition silicone promoted a better marginal adaptation of the provisional prosthetic materials tested, followed by condensation silicone, laboratory silicone, and irreversible hydrocolloid.

Comparison of three dimensional accuracy of two implant level impression techniques; using three different elastomeric impression materials-an in vitro study

Aim: To compare 3-Dimensional accuracy of open and closed impression technique using three elastomeric impression materials to transfer the intraoral position of implant fixture to the working cast. Objective: To compare 3-Dimensional accuracy of open and closed tray impression technique by using addition silicone, condensation silicone and polyether impression materials for making implant level impressions. Materials and Methods: Experiments was conducted to find the three dimensional accuracy of casts made with three impression materials for implant impressions by open and closed tray impression techniques. Five implant analogs were placed on a maxillary acrylic model; impression posts were screwed to implant analogs. 30 stock trays and 30 open window custom trays were prepared. These 30 stock trays and 30 open window custom trays were again divided into three subgroups by using three impression materials. Then the impressions were poured using die stone according to manufacturer’s instructions. Specific dimensions of resultant cast was measured. The dimensional changes were measured using White light laser scanner and data analysis was done by XOV Rapidform Software. Comparison between materials was done by ANOVA test followed by Tukey’smultiple comparison test. Comparison between two techniques was done by unpaired‘t’ test. Results: The data was subjected to statistical analysis which was done by ANOVA test followed by Tukey’s multiple comparison test and Comparison between two techniques was done by unpaired‘t’ test. Statistical analysis shows significantly less difference in open tray technique when compared to closed tray impression technique. Conclusion: Within the limitation of this study;1. Open tray impression technique is more accurate than the closed tray impression technique for making implant impression; 2. Polyether and Addition silicone elastomeric impression materials were there commended materials for implant impressions. Keywords:

Evaluation of the effect of storage time and disinfectant solutions on the dimensional accuracy of impression materials with digital radiography.

The dimensional accuracy of impression materials has been evaluated for a long time, but thus far, digital radiography has not been used for this purpose. The dimensional accuracy of impression materials is very important for the final adaptation of dental prostheses. The objective of this study was to evaluate the effects of different disinfectant solutions and storage times on the dimensional stability of different impression materials by means of digital radiography. Polyether (PE), hydrocolloid (IH), condensation silicone (CS), and addition silicone (AS) materials were used for preparing impressions, taken from an acrylic master model with 2 vertical and 2 horizontal reference points. Water (W), sodium hypochlorite (SH) and a disinfectant solution without aldehyde (Z) were applied on the impressions. Half of the impressions were poured over immediately and half of them - 1 day after. Digital radiography was used to determine the dimensional accuracy of the impression materials. The data was analyzed with a variance analysis and Tukey's multiple comparison test. While PE showed the smallest dimensional changes, IH showed the greatest in all lines. Applying SH and pouring 1 day after caused the greatest dimensional changes in all impression materials. Different disinfectant solutions and storage times had a different effect on the impressions, but the dimensional changes were clinically acceptable.

Evaluation of the Bond Strength of Universal Tray Adhesives on Silicone Impression Materials Using an Acrylic Tray

To evaluate the bond strength of two commercially available universal tray adhesives on polyvinylsiloxane addition silicone and condensation silicone impression materials to an autopolymerizing polymethyl methacrylate acrylic tray material. Sixty flat square specimens were fabricated from autopolymerizing polymethyl methacrylate tray material to which an eye hook was incorporated to serve as the point of attachment to a universal testing machine. A polyvinyl chloride (PVC) pipe of 15 mm diameter and 25 mm long was used to house the impression material, and a metal rod was inserted into two centered holes to provide retention that serves as the second point of attachment to the universal testing machine. The specimens were divided into 4 groups of 15 specimens each. The first and second groups of specimens were applied with Coltene and Zhermack universal tray adhesives and tested with addition silicone impression material. The third and fourth groups were coated with the above-mentioned adhesives, respectively, and tested with condensation silicone. Each specimen was then attached to the universal testing machine. The maximum force at which separation failure occurred was divided by the area of adhesion and recorded as the adhesive strength in MPa. A significant difference was observed between mean MPa values of Zhermack and Colten universal tray adhesives, where the F value of 1314.116 was found to be significant at 0.000 levels indicating that the Zhermack adhesive had higher MPa than Coltene adhesive. Impression material again indicated significant difference (F = 132.514; p = 0.000), where addition silicone had higher MPa value than condensation silicone. Also, the interaction between adhesive and impression material was found to be significant (F = 10.794; p = 0.002). The adhesive bond strength of Zhermack universal tray adhesive was higher compared to that of Coltene universal tray adhesive irrespective of the elastomeric impression material. It was also found that bond strength of Zhermack universal tray adhesive with addition silicone impression material was the highest and Coltene universal tray adhesive with condensation silicone impression material was the least of all the four groups. Tray adhesives need to be applied to the tray to obtain an accurate and consistent impression. If there is a separation of impression materials from the tray, it may results in a distorted impression leading to poor final restorations.

Effect of techniques, trays and materials on accuracy of impressions clinically made

Abstract Introduction Making accurate and dimensionally stable impressions to duplicate oral conditions and tooth morphology is an essential step of prosthetic dentistry for fabricating well-fitted indirect restorations and, consequently, ensure the longevity and success of the treatment. Several authors describe pros and cons of different impression techniques, although there is no unanimity among them about the best one. Objective This study evaluated casts’ accuracy made by different impression techniques, trays and materials. Material and method 10 patients were selected and 20 impressions from teeth #13 to #16 were performed using single-step (SS) and two-step techniques, made with metal stock and customized acrylic resin partial trays, vinyl polysiloxane and condensation silicone rubbers. Type IV gypsum was used to pour the casts. Three photographs of each patient (baseline), as their respective gypsum casts, were taken, measured in their interested buccal surface area. Comparisons of area values among experimental groups and baseline were performed. Data showed adherence to normal curve, being submitted to 3-way ANOVA/Bonferroni test (α=.05). Result Technique produced significant differences (P=0.02). SS technique was more accurate than BUR one (P=0.003; 95=1.22 to 5.98), but both resulted in similar casts to PVC, MOV and NR techniques, which were similar to each other (P&gt;0.05). Conclusion SS technique showed the closest absolute values to baseline.