Polyether Impression Material Research Articles

Dimensional Accuracy of Novel Vinyl Polysiloxane Compared with Polyether Impression Materials: An In Vitro Study.

Transferring the intraoral situation accurately to the dental laboratory is crucial for fabricating precise restorations. This study aimed to compare the dimensional accuracy of a new hydrophilic quadrofunctional vinyl polysiloxane (VPS) and polyether (PE), in combination with different impression techniques (mono-phase single step or dual-phase single step). The reference model simulated a partially edentulous mandible. Stainless-steel precision balls were welded to specific teeth and were used to detect dimensional deviations. Fifteen impressions were made for each of the following four test groups: (1) VPS mono-phase, (2) PE mono-phase, (3) VPS dual-phase, and (4) PE dual-phase. Global accuracy was measured by deviations from the reference model, while local accuracy focused on the trueness and precision of abutment tooth surfaces. Statistical analysis was conducted using ANOVA (α = 0.05). All distances were underestimated, with the highest global inaccuracies for the cross-arch distance, ranging from -82 µm to -109 µm. The abutment tooth surfaces showed excellent local accuracy for all the materials and techniques, with crown surface trueness < 10 µm and precision < 12 µm. Inlay surfaces had higher inaccuracies (trueness < 15 µm, precision < 26 µm). Within the limitations of this study, all impression materials and techniques can be used to produce models with clinically acceptable accuracy.

Evaluation of the effect of chemical disinfection and ultraviolet disinfection on the dimensional stability of polyether impression material: an in-vitro study

BackgroundVarious methods, chemical and physical, disinfect dental impressions. Common chemicals include 1% Sodium Hypochlorite and 2% glutaraldehyde, while UV radiation is a prevalent physical method. Few studies compare their effects on dimensional stability in polyether impressions. This study aims to assess such stability using different disinfection methods. Therefore, this study was planned to evaluate the dimensional stability of polyether impression material using different disinfection methods.MethodsThis in vitro study compared the effects of chemical disinfectants (1% Sodium Hypochlorite and 2% glutaraldehyde) and UV irradiation on the dimensional stability of polyether impression material. Groups A, B, C, and D, each with ten samples (N = 10), were studied. Group A was untreated (control). Group B was treated with 2% glutaraldehyde for 20 min, Group C with 1% Sodium Hypochlorite for 20 min, and Group D with UV rays for 20 min. A pilot milling machine drill was used to make four parallel holes labeled A, B, C, and D in the anterior and premolar regions from right to left. After sequential drilling, four implant analogs were positioned using a surveyor for accuracy. Ten open-tray polyether impressions were made and treated as described in the groups, followed by pouring the corresponding casts. Distortion values for each disinfection method were measured using a coordinate measuring machine capable of recording on the X- and Y-axes.ResultsA comprehensive analysis was conducted using the one-way ANOVA test for distinct groups labeled A, B, C, and D, revealing significant differences in the mean distances for X1, X2, X4, X5, and X6 among the groups, with p-values ranging from 0.001 to 0.000. However, no significant differences were observed in X3. Notably, mean distances for the Y variables exhibited substantial differences among the groups, emphasizing parameter variations, with p-values ranging from 0.000 to 0.033. The results compared the four groups using the one-way ANOVA test, revealing statistically significant distance differences for most X and Y variables, except for X3 and Y4. Similarly, post-hoc Tukey’s tests provided specific pairwise comparisons, underlining the distinctions between group C and the others in the mean and deviation distances for various variables on both the X- and Y-axes.ConclusionsThis study found that disinfection with 1% sodium hypochlorite or UV rays for 20 min maintained dimensional stability in polyether impressions.

Evaluation of Dimensional Change in Different Elastomeric Impression Materials Used in Implants: An Original Research

ABSTRACT Aim: The study’s objective was to assess the dimensional accuracy of hybrid polyether and polyvinyl siloxane materials for implant impressions. Materials and Methods: Nine groups were created from 45 samples of various building materials and construction techniques from the study. Five samples were tested, and 45 impressions were recorded. Results: The hybrid non-splinted technique has improved implant site replication, accuracy, and low interimplant distance alterations. Conclusion: The finest possible reproduction of implant sites on the master cast was made feasible by the use of an open, non-splinted method and a hybrid polyvinyl siloxane–polyether impression material.

A Comparative Study to Assess Accuracy of Casts Prepared using Direct Impression Technique with and without Splinting of Multiple Dental Implants Utilising Two Different Splinting and Impression Materials.

The current study examined the accuracy of casts generated using direct impression processes with and without splints for multiple dental implants utilizing two different splinting materials and impression materials. Dental replacement base intensity alleviating acrylic tar was used to create a reference model of a mandible with four inserts (Uniti, Equinox, D-3.7 mm, and L-13 mm) in the front. Polyether and polyvinyle siloxane impression materials were used to make impressions of the reference model utilizing direct non-splinted and splinted techniques. Polyether impression material was found to produce more accurate impressions than polyvinyl siloxane, and impressions made using transfer copings splinted with pattern resins were found to be more accurate than those made using either unsplinted copings or copings splinted with light-cured wax resin. All six impression techniques resulted in casts that were different from the reference model. Next, the polyether-splinted (SPR) technique is the nonsplinted technique employing polyether and polyvinyle siloxane imprint materials, and then, the splinted techniques using polyether and polyvinyle siloxane and produced the most accurate casts in comparison with the reference model.

Multiscale Evaluation of Jaw Geometry Reproduction Obtained Via the Use of Selected Orthodontic Materials in Dental Implants and Orthodontics—In Vitro Case Study

In this paper, the multiscale analysis of the reproduction accuracy of jaw geometry obtained via the use of selected orthodontic materials is discussed. Impressions were made from two types of impression material. An accuracy assessment of the model geometry mapping was performed using noncontact systems, including a fringe projection optical 3D scanner, computed tomography, and a focus variation microscope. Measurements were made in three modes for comparison, as were the silicone and polyether impression materials. These modes were a jaw model and impression, an impression and plaster model, and plaster and jaw models. The research results are presented as colorful maps of deviations. Data analysis showed that deviations were the smallest in the case of silicone and that the best fit occurred between the silicone impression and the plaster model. The conducted research confirmed the validity of the assumptions considering the use of multiscale analysis for geometric analysis. The use of modern multiscale measurement methods allows for shorter and more efficient prosthetic operations. At present, these devices are expensive and complicated to use, but developments in technology should simplify the process, and prosthetic professionals should be aware of the possibilities described in the paper.

Comparative evaluation of linear dimensional accuracy of impressions made with different elastomeric impression materials (Polyether and Polyvinyl siloxane) in angulated and parallel implants-An invitro study

To date no technique has been proven to guarantee a completely passive fit of implant supported prosthesis framework. Several clinical variables such as angulation of implants, impression material and technique used may affect the precision of impressions. Hence, this study is designed to evaluate and compare the dimensional accuracy of the resultant casts made from open tray implant level impressions with two different impression materials (polyvinyl siloxane and polyether) in parallel and angulated implants. The study consisted of two control groups; master model –1with parallel implants and master model –2 with angulated implants. From master model 1and master model 2, total 40 implant level open tray impressions were made using PVS and polyether impression material and impressions were poured to obtain 40 study casts. The resultant casts were divided into 4 groups (10 casts in each group), according to the impression material used (PVS or Polyether) and implant’s orientation (parallel or angulated) in the casts. All casts were evaluated for the positional accuracy of the implant by using four reference distances with the help of a profile projector. These measurements were compared to the measurements calculated on the master model, which served as a control. The variations of the mean distance values with respective control values within a group were analyzed with one samples’ t’ test at 0.05 significance level. Further the mean distance variations between the groups were analyzed with independent samples ‘t’ test to evaluate group mean variations.The impressions made in the presence of angulated implants were significantly less accurate than the ones made with parallel implants. Regarding impression material the tested polyether resulted advantageous over polivinylsiloxane impression material in terms of recording positional accuracy of implants.

Evaluation of the properties of a new super quick-setting (2 min) polyether impression material

ObjectivesAlthough a new super-quick setting polyether impression material has been commercially recently introduced, its properties have not been yet reported. Thus, it was the aim of this study to assess the dimensional stability, tear strength, and elastic recovery of the new material and to compare it with another commonly used polyether and polyvinyl siloxane.Materials and methodsA new super-quick set polyether, a regular set polyether and a polyvinylsiloxane (PVS) impression material have been used in the study. Dimensional changes were measured using a modified mold as per ISO 4823:2000 after 1 h and 7 days. Tear strength was evaluated by subjecting specimens to tension until failure with a crosshead speed of 250 mm/min. Elastic recovery was measured by deforming specimens using a materials testing machine to a height of 16 mm (20% strain). The change in length (ΔL) was measured afterwards and elastic recovery was calculated in percentages.ResultsDimensional changes of the super quick and regular set polyether were comparable in both the vertical and horizontal dimensions after 24 h and 7 days. All the tested materials showed dimensional change values far below the maximum accepted ISO requirement (1.5%). The super quick setting polyether showed significantly improved tear strength (4.9 N/mm) in comparison to the regular set polyether (3.5 N/mm) and similar to PVS (5.2 N/mm). The elastic recovery of PVS (99.6%) was the highest among all the groups.Conclusions and clinical relevanceThe newly available super-fast set polyether offers a great potential for a reduced chair side time and comfort for both, the patient and the dentist. Super quick polyether showed as well improved tear strength, which is considered one of the shortcomings of the regular set polyether. In addition, the new polyether was as accurate as the regular set polyether and with good elastic recovery.

An unconventional impression method using implant mount: an alternative to open-and closed-tray impression technique

Background:Various impression techniques have been proposed for making implant prostheses. Impressions are made at implant level –closed and open tray impressions, as well as abutment level impressions. Closed and open tray copings are used to make the impressions. The limitations associated with the implant impression copings, including expensive ones, pose a significant challenge in limited mouth-opening cases, and customization of copings is not feasible.Aim: This study aimed to compare the dimensional accuracy of four impression methods, open-tray, closed-tray, disposable mount as coping and splinted mount as coping.Materials and methods:An ideal maxillary edentulous acrylic model was used with windows created at the canine and molar regions. Four analogues were implanted in the canine and molar areas to represent implants. The analogues were parallel to one other and were orientated at 0 degrees using the surveyor's assistance. Four groups were made: closed-tray, open-tray, implant mount as coping and splinted mount as coping. The custom trays were fabricated, accordingly. The implant-level impressions were made in all the groups using polyether impression material. The impressions were fitted with their respective impression copings with the analogues. The impressions were poured using die stone type-IV, and the casts were made. The resulting casts were 3D scanned, and a virtual model (.stl File) was created. Each .stl file was subjected to Geomagic software to evaluate the three-dimensional accuracy of conventional implant copings and implant mount as copings. Results:The Open-tray and the closed-tray groups exhibited the mean dimensional accuracy of 0.011±0.0016 μm and 0.018±0.0012 μm, respectively. The mount as coping and splinted mount displayed a mean dimensional accuracy of 0.017±0.0008 μm and 0.013±0.0020μm, respectively.Conclusions:This pilot study concludes that the implant mountcan be used as implant impression coping and an alternative to the conventional impression coping.

Disinfection Procedures and Their Effect on the Microorganism Colonization of Dental Impression Materials: A Systematic Review and Meta-Analysis of In Vitro Studies.

Dental impressions are contaminated with potentially pathogenic microorganisms when they come into contact with patient blood, saliva, and plaque. Numerous disinfectants are used; however, no sole disinfectant can be designated as universal for all the impression materials. Thus, the aim of this study is to systemically review the literature to evaluate the effect of the existing disinfection procedures on the bacterial colonization of dental impression materials. This systematic review and meta-analysis was conducted according to the PRISMA statement. PubMed (MEDLINE), Web of Science, Scopus, EMBASE, and SciELO databases were screened up to April 2021. Eligibility criteria included in vitro studies reporting the antibacterial activity of disinfectant solutions in dental impression materials. The meta-analysis was performed using Review Manager (version 5.3.5). A global comparison was performed with the standardized mean difference based on random-effect models at a significance level of α = 0.05. A total of seven studies were included in the meta-analysis. The included studies described the effect of disinfection processes with chlorhexidine gluconate, alcohol, sodium hypochlorite, glutaraldehyde, and hydrogen peroxide in alginate, polyvinyl siloxane, and polyether impression materials. The meta-analyses showed that the use of chlorhexidine, alcohol, glutaraldehyde, and sodium hypochlorite reduced the colony-forming units by a milliliter (CFU/mL) in alginate (p < 0.001). On the other hand, glutaraldehyde, sodium hypochlorite, and alcohol reduced the CFU/mL in polyvinyl siloxane (p < 0.001). Finally, alcohol and glutaraldehyde reduced the CFU/mL in polyether material (p < 0.001). High heterogenicity was observed for the alginate and polyvinyl siloxane materials (I2 = 74%; I2 = 90%). Based on these in vitro studies, the disinfection of impression materials with several disinfection agents reduces the CFU/mL count.

The Accuracy of Open-Tray vs. Snap on Impression Techniques in A 6-Implant Model: An In Vitro 3D Study.

To compare the three-dimensional accuracy of an open-tray and two snap on impression techniques (with and without connecting the plastic caps of the snap on impression transfers) in a full arch 6-implant model, a reference acrylic resin model of the maxilla with six implants was fabricated. Prominent geometrical triangles, in the palate area, served as reference points for a digital overlap between scans. Three impression transfer techniques were evaluated and compared: open-tray direct impression (DI), snap on impression (SpO), and connected snap on impression (SpOC). Polyether impression material was used to make 30 impressions (n = 10), and the master model and all casts were digitally scanned with a laboratory optical scanner. The obtained 3D data were converted and recorded as STL files, which were imported to a 3D inspection software program. Angular deviations (buccal, occlusal and interproximal planes) between the study casts and the reference model were measured. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey post hoc test, with 0.05 used as the level of significance. The 3D angular deviations from the master model revealed no significant differences between the DI and SpO impression groups, but there were significant differences in the SpOC impression group, particularly in the buccal and occlusal planes. In all groups, the 3D angular deviation between the most distal scan abutments on each side of the model was significantly different from all other areas when compared to the master model. Within the limits of this study, it is possible to conclude that the indirect closed tray snap on impression technique with unconnected plastic caps exhibited the same three-dimensional accuracies as the direct open tray technique. The indirect closed tray snap on impression technique with connected plastic caps was less accurate than either the indirect closed tray snap on impression technique with unconnected plastic caps or the direct open tray technique. In the case of full arch implant supported prostheses, inaccuracies may be expected in the most distal implants for all the three impression techniques evaluated in this study. Further in vitro and in vivo research is required.

Three-dimensional accuracy of innovative implant-level impression techniques with plastic snap-on impression copings.

Several studies have assessed the accuracy of the indirect snap-on impression technique. However, some impression techniques that utilize plastic snap-on impression copings have not yet been investigated. This study aimed to assess the three-dimensional (3D) accuracy of innovative implant-level impression techniques with plastic impression copings and the splinted open-tray technique with metal impression copings. This in vitro study used a reference model of the mandible with 4 parallel dental implants. Forty impressions were made with polyether impression material, using the splinted opentray technique with metal impression copings (SOM group), the non-splinted closed-tray technique with snap-on impression copings (NCS group), the non-splinted open-tray technique with snap-on impression copings (NOS group), or the splinted open-tray technique with snap-on impression copings (SOS group); n = 10 per group. Linear discrepancies in the inter-implant distances on the obtained casts were determined in the X, Y and Z axes with the use of a coordinate measuring machine. Subsequently, the 3D accuracy of each impression technique was calculated. Data was analyzed by means of the one-way analysis of variance (ANOVA) followed by Tukey's post-hoc tests. Among different impression techniques, the amount of linear discrepancy was significant only for the Z axis. The SOM, NOS and SOS groups showed less discrepancy in this axis as compared to the NCS group (p < 0.001). A significant difference was also noted in 3D discrepancy (p = 0.022), with the SOM group showing a significantly higher discrepancy as compared to the SOS group (p = 0.016). The 3D accuracy of the implant-level splinted open-tray impression technique with plastic snap-on impression copings was significantly higher than that of the splinted open-tray technique with metal impression copings.

Comparative Assessment of Width of Neutral Zones Recorded Using Two Neutral Zone Impression Methods (Phonetic and Swallowing) and Two Different Materials (Tissue Conditioner and Polyether)

Abstract Statement of Problem: Medium body polyether impression material has been recently used as neutral zone recording material. However, there is a lack of studies comparing it with routinely used material. Purpose: The purpose of the study is to compare neutral zone width of phonetic (PNZ) and swallowing (SNZ) neutral zone impression techniques with a tissue conditioner and a polyether impression material within the same subjects. Materials and Methods: Assessments of neutral zone width were carried out in ten completely edentulous patients with advanced mandibular resorption. On each patient, four neutral zone impressions were recorded as follows: SNZ with tissue conditioner material, PNZ with tissue conditioner material, SNZ with polyether impression material, PNZ with polyether impression material. Putty indices were made of each neutral zone and traced on graph paper. The buccolingual measurements were made at five different locations, midline, right first premolar, left first premolar, right first molar, and left first molar. Statistical analysis was done using Mann–Whitney U test. Results: There was no significant difference observed when comparison was done either between materials or techniques. Conclusion: Medium body polyether can be a viable alternative to conventional tissue conditioner material and can be used with both swallowing and phonetic techniques with equal efficacy.

Comparative Assessment of Precision of Prepared Single Tooth using Shining 3D Intraoral Scanner and Conventional Impressions Made using Polyvinyl Siloxane and Polyether Impression Material – An In vitro Study

Comparative Assessment of Precision of Prepared Single Tooth using Shining 3D Intraoral Scanner and Conventional Impressions Made using Polyvinyl Siloxane and Polyether Impression Material – An <i>In vitro</i> Study

Comparative surface detail reproduction for elastomeric impression materials: Study on reproducibility performance.

For dental impression of a prepared tooth, the goal is a void-free negative representation from which an accurate cast of a tooth and its surrounding tissue can be reproduced. This in-vitro study assessed and compared the reproduction accuracies of surface detail obtained with three different dental elastomeric impression materials: vinyl polysiloxane (VPS), vinyl polyether silicone (VPES), and polyether (PE). A stainless-steel model with two abutments was used, with impressions taken 10 times for each material, for 20 abutment impressions per group, using a two-phase, one-step technique (heavy body/light body). The impressions were removed and assessed for numbers of enclosed voids and open voids visible on the surface. The defect frequency was 95% for impressions with the VPS and VPES materials, and 30% for the PE material. No significant differences were seen for number of impressions with defects for VPS versus VPES. Significant differences were seen for VPS and VPES versus the PE material (P <.05). No significant differences were seen for the defect type distributions across these three impression materials. The PE impression material showed better accuracy for reproduction of surface detail of these dental impressions compared to the VPS and VPES impression materials.

Assessment of Effect of Different Sterilization Agents on Dimensional Accuracy of Different Impression Materials in Implant Prosthesis - An In vitro Study.

Aim:Sterilization of impression materials is of paramount importance. The present study was conducted to compare the effect of different disinfectants on dimensional accuracy of elastomeric impression materials used for implant prosthesis and other routine treatments.Materials and Methods:The present study was conducted with polyvinyl siloxane (PVS) (regular body), PVS (medium body), PVS (heavy body), and polyether (medium body) impression materials. Glutaraldehyde (2%) and sodium hypochlorite (NaOCl, 0.525%) were the disinfectant solutions employed in the study. After 16 h, the specimens were measured under Leica WILD stereomicroscope and dimensions were compared with master die.Results:The dimensional change in the Controls, 2% glutaraldehyde (Group I), and 0.525% NaOCl (Group II) was non significant where as Group III and Group IV showed statistically significant difference (P < 0.05). Results also showed significantly higher tear strength (newton/millimeter) in Control group followed by Group I and Group II.Conclusion:PVS (heavy body) was found to be most stable, and polyether was seen to be stable of all the impression materials.

Fractured alveolar process displacement evaluation-Effect of the rigidity of wire-composite splints.

Traumatic dental injuries with bone fractures require rigid splinting. The degree of rigidity of the wire-composite splints can be challenging. The aim of this study was to evaluate the effect of the rigidity of different wire-composite splints on alveolar process displacement. A model was created using polystyrene resin to simulate the anterior maxilla, bovine incisors to simulate maxillary incisors, and polyether impression material to simulate the periodontal ligament. An alveolar process fracture was created, while maintaining the labial bone connection with the PDL. Four wire-composite splints (0.3, 0.6, 0.9, and 1.2mm in diameter) were compared with models without splints and with no fracture (n=5). The alveolar process displacement was measured (3 times per model/per splint type) at the fractured and adjacent central incisor regions using a deflectometer (Instron) under functional cycling and static loading (100N). Data (μm) were analyzed using RM ANOVA, followed by Tukey's HSD test (α=0.05). The displacement at the region of the adjacent incisor was not influenced by the splint during static and cycling load (P>.05). The Tukey test demonstrated that the model without splints had significantly higher alveolar process displacement at the traumatized teeth than that of all other splint models (P<.001). Increasing the wire diameter from 0.3mm to 0.9mm significantly reduced the alveolar process displacement (P<.001). No difference was observed between the 0.9mm (P=.123) and 1.2mm (P=.219) wire-composite splints irrespective of the measured tooth regions. The rigidity of the wire-composite splint significantly influenced the mobility of the fractured alveolar process. The use of at least 0.9mm wire was effective in reducing the fractured alveolar process displacement to a level that was similar to the adjacent teeth.

The Effect of Adhesive Material and Surface Roughness on the Tensile Bond Strength between Some Elastomeric Impression Materials and Cold Cure Acrylic

: The detachment of impression materials from impression tray is considered as an important problem which is difficult to be detected clinically. Several attempts were used to handle this problem, as roughening the surface of the tray, perforating it, or by the use of adhesive solutions which are recommended to be used by manufacturers. Objectives: To determine the tensile bond strength of two elastomeric impression materials; polysulphide and polyether to cold-cure acrylic resin disks with or without tray adhesive application at different drying and surface treatment. Material and Methods: Eighty specimens prepared consisted of two disks with impression material sandwiched between, then divided into two groups; 40 specimens for each type of impression. The “PD” hold adhesive material was applied on the acrylic surfaces which were smooth and rough. The adhesive was allowed to dry for 2, 5, and 10 minutes before the application of impression materials. To determine tensile bond strength at the interface between the adhesive-acrylic, and the adhesive-impression materials, a universal Instron testing machine was used. Results: Polyether impression material showed higher tensile bond strength to cold-cure acrylic than polysulphide impression material, without adhesive application. However, after adhesive application, the bond strength to polyether decreased, while for polysulphide increased significantly. Roughening the acrylic surface significantly increased the bond strength for both impression materials with or without adhesive application. Also, increasing the drying time from 2 up to 10 minutes significantly increased the bond strength for both impression materials, and smooth and rough acrylic surfaces. Conclusions: Polyether impression showed higher bond strength to cold-cure acrylic than polysulphide impression, without adhesive application.

EFFECT OF DIFFERENT BITE RECORDING MATERIALS ON MOUNTING ACCURACY OF WORKING CAST

Objective: To assess effect of different bite recording materials on accurate mounting of working casts. Materials and Methods: A 40 maxillary and mandibular stone casts were obtained from dentoform teeth using polyether impression material. Derived stone casts were divided according to bite registration material in to four groups (10 samples each); 1. wax group, 2. polyvinyl siloxane group, 3. polyether group and 4. Bis-crylic resin group. Ten bite records were obtained with poly vinyl siloxane recording material from hand articulated dentoform to serve as control group. The 40 produced mandibular stone casts were mounted on semi adjustable articulators using four bite registrations tested materials. Unilateral Polyvinyl siloxane bite registration were made for 40 mounted stone casts to evaluate bite registration accuracy. Then bite records were placed on a light box and a camera set at a fixed distance 8 inches was used to capture the light transmission that was projected through the bite material. The camera transferred the information to an image analysis program (ImageJ) which measure accuracy of registration materials. Results: Grey scale data showed parametric distribution while measurement error showed non-parametric distribution. The difference between tested groups and control group was compared using ANOVA test. The results revealed that, the different between test groups and control was insignificant (P-value = 0.104). Conclusions: All tested bite registration materials had comparable results, although Luxabite and polyether showed higher errors than polyvinyl siloxane and wax.

Comparative Study of Dimensional Stability and Detail Reproduction of Reformulated and Nonreformulated Elastomeric Impression Materials.

To evaluate the dimensional stability and the detail reproduction of five current elastomeric impression materials in vitro. The materials examined were: 3 different polyether impression materials, a vinyl polysiloxane impression material, and a vinyl polyether silicone impression material. All impression materials were of a medium viscosity. One stainless steel die was fabricated according to the ANSI/ADA specification no.19 criteria. Twenty impressions of this die were made for each material. Dimensional accuracy and surface detail were evaluated 24 hours after making the impressions using a measuring microscope. The data were analyzed using Welch's analysis of variance, Games-Howell Post-Hoc, and the Pearson's chi-square tests (α = 0.05). Statistical differences were observed in the mean percent dimensional stability (F [4,47] = 39, p < 0.001) of the tested impression materials. The highest dimensional change was recorded for the vinyl polysiloxane impression material, with a mean percent value of -0.09 ± 0.02% (p < 0.001). The lowest dimensional change was recorded for the Monophase polyether material with a mean percent value of -0.03 ± 0.01% (p < 0.038). The best surface detail reproduction results were obtained using the Monophase polyether material (90% acceptable impressions), with no significant differences (χ² [4] = 3.86, p = 0.483) observed between the Monophase and the rest impression materials. All materials exhibited acceptable dimensional stability, well below the ANSI/ADA specification no.19 standard of ≤0.5% dimensional change. All impression materials demonstrated acceptable surface detail reproduction with no significant differences between them.

COMPARATIVE CHARACTERISTICS OF TRANSFERS SPLINTING TECHNIQUES IN THE PROCESS OF TAKING ONE-STAGE DOUBLE-LAYERED DENTAL IMPRESSIONS BY MEANS OF OPEN TRAY IMPRESSION TECHNIQUE

Abstract. According to conclusions of ITI World Congress (2018), the accuracy of the dental impression determines the quality of the working model and, consequently, the fixation of the prosthetic restorations at the final stage. Inaccurate dental impression will inevitably lead to technical and biological complications (Wolfart S., 2016). According to Lee and co-authors (2019), the accuracy of the dental impression is influenced by the chosen method, namely closed or open tray, the presence or absence of transfers splinting and the choice of impression material type.&#x0D; The most accurate impression has been proved to be an impression taken with the use of an open tray impression technique, by means of polyether impression material with preliminary transfers splinting using internally interfaced implant system.&#x0D; The objective of the research was to evaluate the quality of implants placement transferring to the model by comparative analysis of different methods of clinical transfers splinting in order to take impressions using an open tray impression technique.&#x0D; Twelve clinical situations were studied. Four groups were formed according to the method of transfer splinting. Each group included 3 clinical cases. Impressions were taken with the use of an open tray impression technique in all clinical cases with preliminary custom-made trays with holes in the implants projections.&#x0D; A grading scale was created when assessing the quality of transfer splinting as a key factor in the accuracy of implant placement transferring.&#x0D; Each of the groups received from 1 to 4 points where 1 point was the worst result according to this criterion and 4 points meant the best one. Among the criteria for splinting quality evaluation, 1-3 criteria were considered to be subjective, criterion 4 was considered to be objective. Therefore, criterion 4 received coefficient ×2 in order to increase the objectivity of the results evaluation.&#x0D; There were 4 criteria:&#x0D; &#x0D; The simplicity of the technique and the time spent splinting.&#x0D; The cost of the technique.&#x0D; Passivity when fixing the bridge prosthetic restoration after manufacturing.&#x0D; Radiologically measured distance between the centers of implant analogues on the model relative to each other after an impression taking by means of different splinting techniques and deviation of the value from the position of the centers of implants heads tops after osseointegration according to CT scan.&#x0D; &#x0D; Analyzing the results of the research, splinting techniques were ranked according to the obtained points.&#x0D; Research group 1 scored 6 points using dental floss and flowable compomer. A considerable amount of time was spent splinting with relatively inexpensive technology. The passivity of the fixation was the worst in comparison with other methods and the largest error was determined radiographically.&#x0D; Group 4 scoring 17 points was determined as the best of the chosen techniques. Despite the high cost of the chosen technique, prosthetic restorations made after transfers splinting by means of this technique had the highest fixation accuracy and the lowest deviation of the implants analogues on the model radiographically in comparison with the position of the implants in the upper alveolar ridge and lower alveolar ridge due to the cost of the material based on poly-vinyl siloxane.