Elastomeric Impression Research Articles

Comparative Evaluation of Dimensional Stability of Elastomeric Impression Materials Subjected to Ultraviolet Irradiation and Spray Atomized Disinfection: An In Vitro Study

Comparative Evaluation of Dimensional Stability of Elastomeric Impression Materials Subjected to Ultraviolet Irradiation and Spray Atomized Disinfection: An In Vitro Study

In vitro Evaluation of Implant Impression Techniques and Elastomeric Materials: A Comparative Dimensional Accuracy Study

Abstract Context: Dimensional precision in implant impression. Aims: The purpose of this study was to comparatively evaluate the dimensional accuracy of two implant impression techniques with two different variants of vinyl polysiloxane impression material. Material and Methods: The edentulous mandible reference model was fabricated in clear resin. In the anterior region of the mandibular ridge, three dummy implants were placed in a spread-out configuration. Impressions were made using two elastomeric impression materials and two impression techniques using customised impression trays. Finished casts were then divided into four groups having four samples each. The mean centre-to-centre distances between adjacent analogues (in sample casts) and between adjacent implants (in the control cast) were measured with the help of a profile projector. Statistical Analysis Used: Data were analysed using Student’s t-test. Results: The open-tray technique showed more accurate results with a combination of medium body and light body, whereas in the closed tray technique, mono-phase vinyl polysiloxane appeared to be a better option. Amongst all, mono-phase with closed tray provided statistically significant results. P < 0.05 in Group C and other group’s P ≥ 0.05. Conclusions: Within the limitations of this study, both implant impression techniques appeared to be equally accurate depending on clinical conditions, temperature and time of the procedure. However, mono-phase impression material with closed tray provided statistically significant results.

Technique for Spacer Adaptation and Custom Tray Fabrication in Impression Making for Fixed Prosthodontics.

The objective is to minimize the inaccuracies in two-step impressions by homogenizing the polymerization shrinkage of elastomeric impression material in fixed prosthesis fabrication. The objective is accomplished by the technique of spacer adaptation and custom tray fabrication for two-step impressions. The technique makes the use of two vacuum-adapted spacers, selected based on the viscosity of elastomeric impression, and a vacuum-adapted custom tray. The procedure of using the specially fabricated custom tray for impression making is also presented. Consistent thickness of the two different viscosities of impression material is maintained due to vacuum adaptation of the spacers. This homogenizes the polymerization shrinkage of the elastomeric material in different regions of impression, as uniform space is occupied by the material in the space created by the spacer. The procedure of vacuum adaption of the tray material also limits the dimensional change of the tray. The technique minimizes the inaccuracies of impression by homogenizing the polymerization shrinkage of the elastomeric impression, thus promising a well-fitting prosthesis.

Assessment of dimensional stability of novel VPES impression material at different time intervals with standard disinfectants

BackgroundVinyl polyether silicone (VPES) is a novel impression biomaterial made of a combination of vinyl polysiloxane (VPS) and polyether (PE). Thus, it is significant to assess its properties and behaviour under varied disinfectant test conditions. This study aimed to assess the dimensional stability of novel VPES impression material after immersion in standard disinfectants for different time intervals.MethodsElastomeric impression material used –medium body regular set (Monophase) [Exa’lence GC America]. A total of 84 Specimens were fabricated using stainless steel die and ring (ADA specification 19). These samples were distributed into a control group (n=12) and a test group (n=72). The test group was divided into 3 groups, based on the type of disinfectant used - Group-A- 2% Glutaraldehyde, Group-B- 0. 5% Sodium hypochlorite and Group-C- 2% Chlorhexidine each test group was further divided into 2 subgroups (n=12/subgroup) based on time intervals for which each sample was immersed in the disinfectants – subgroup-1- 10 mins and Subgroup 2- 30 mins. After the impression material was set, it was removed from the ring and then it was washed in water for 15 seconds. Control group measurements were made immediately on a stereomicroscope and other samples were immersed in the three disinfection solutions for 10 mins and 30 mins to check the dimensional stability by measuring the distance between the lines generated by the stainless steel die on the samples using a stereomicroscope at x40 magnification.ResultsThe distance measured in the control group was 4397.2078 µm and 4396.1571 µm; for the test group Group-A- 2% Glutaraldehyde was 4396.4075 µm and 4394.5992 µm; Group-B- 0. 5% Sodium hypochlorite was 4394.5453 µm and 4389.4711 µm Group-C- 2% Chlorhexidine was 4395.2953 µm and 4387.1703 µm respectively for 10 mins and 30 mins. Percentage dimensional change was in the range of 0.02 – 0.25 for all the groups for 10 mins and 30 mins.Conclusions2 % Glutaraldehyde is the most suitable disinfectant for VPES elastomeric impression material in terms of dimensional stability and shows minimum dimensional changes as compared to that of 2% Chlorhexidine and 0.5% Sodium hypochlorite.

The Accuracy of Casts Obtained Using Different Impression Techniques and Impression Materials in Combined Parallel and Angulated Implants: An In Vitro Study.

Aim The aim of this in vitro study was to evaluate and compare the accuracy of casts made from two elastomeric impression materials (polyvinyl siloxane (PVS) and vinylsiloxanether (VSE)) using different impression techniques on parallel and angulated implants. Materials and methods The reference model was fabricated using auto-polymerizing acrylic resin on which three implant analogs were placed of which two were parallel to each other and the third at 20-degree mesial angulation. A total of 60 impressions were madeof which 30 were by using PVS and 30 by VSE. For each material, 10 impressions were made by closed tray technique, 10 by open tray techniqueand 10 by open tray with sandblasting and adhesive coating of the impression copings technique. The inter-analog distances of the casts obtained were evaluated and compared with the reference model by a vision measuring machine. Data were analyzed using analysis of variance (ANOVA), Tukey's Honest Significant Difference (HSD) post hocand independent samples t-test. Results When the inter-analog distances of the duplicate casts were compared with the reference model, the mean error rates for parallel implants decreased in the order of closed tray technique, open tray technique and open tray with sandblasting and adhesive coating of the impression copings technique for both PVS and VSE impression materials. Similarly, the same order was observed for angulated implants for both impression materials. Using the closed tray technique, there was no statistically significant difference in the accuracy of the cast between the two materials for parallel implants (P = 0.525) and also no significant difference between the two materials for angulated implants (P = 0.307). Similarly, there was no statistically significant difference in the accuracy of the cast between the two materials for parallel implants (P = 0.455) and also no significant difference between the two materials for angulated implants (P = 0.519) using the open tray technique. Whereas for the open tray with sandblasting and adhesive coating of the impression copings technique, VSE produced a more accurate cast than PVS for parallel implants and was statistically significant (P = 0.033); however, there was no significant difference between the two materials for angulated implants (P = 0.375). Conclusion For parallel implants, VSE by an open tray with sandblasting and adhesive coating of the impression copings technique produced a more accurate cast than PVS. For angulated implants, there was no significant difference between the two materials and it was only the technique that significantly affected the accuracy of the cast.

Elastomeric impression materials used in modern orthopedic dentistry

This article presents a review of elastomeric impression materials currently used in orthopedic dentistry. The elastomer group is divided into silicone, polyester, and thiocol (polysulfide) materials. Silicone impression materials are widely used in orthopedic dentistry. Their structural basis is polymethylsiloxane with active terminal hydroxyl groups. Polyester materials consist of the main and catalyst components (pastes). The main component contains a polymer with imine groups, fillers, and plasticizers. Sulfonic acid ester is present in the catalyst paste. When these two components are mixed, ionic (cationic) polymerization occurs. Polysulfide materials are produced as base and catalyst pastes. The structural unit of the main paste is polysulfide or mercaptan rubber, and the catalyst paste acts as an oxidizer. Lead dioxide is often used as an oxidizer. The resulting polymer does not have a stereoregular structure, which causes its stickiness. It is technologically challenging to obtain a polymer with a stereoregular structure.
 When theoretically comparing the listed types of elastomeric impression materials, according to their properties, chemical composition, advantages, and disadvantages, polyester and polysulfide impression materials can be distinguished as more advanced. Silicone materials have disadvantages; however, they are often used for domestic dentistry owing to the presence of domestic manufacturers and relatively low cost.

Modification on Window Technique in Full Edentulous Patient with Hyperplasia

Complete denture is often used by patients that have edentulism. However, a long-term denture wearers commonly showed the hyperplastic growth of tissue called hyperplasia. This condition will present some difficulties for impression and retention. A 77 year old male patient reported to the RSGM UMY with a loose-fitting denture. He has been using it for 10 years. His old denture has suction cup on the palatal which no longer retentive and stable. The clinical examination showed the maxillary and mandibular complete edentulous ridge with flabby ridge area in the maxillary and mandibular anterior region. Patient is given treatment complete denture with acrylic resin material. In this case, window technique is used as the impression technique for a flabby ridge. Denture-induced hyperplasia is a condition of enlarged of fibrous tissue that could leads to poor denture retention, support, and stability. In the presence of hyperplasia, fabrication of as stable denture can be very arduous challenge. Special impression technique, like window technique frequently used on a case with flabby ridge. Window technique is a technique which use medium body impression material for the un-displaceable tissue whereas the flabby tissue impressed by using light body elastomer impression that must be freed from pressure. In patient with flabby ridge or hyperplasia due to denture, fabrication of impression need special technique like window technique which can be proven to ensure a final impression of the flabby ridge to improve denture stability, retention, support, and patient comfort.

Precision Prosthodontic Rehabilitation of Flabby Ridge with a Modified Window Technique: Case Report

Flabby ridge, also known as a soft (mobile), movable, or displaceable ridge, presents a common clinical challenge in dental practice. It primarily affects the alveolar ridges of the upper (maxillary) or lower (mandibular) arches. The anterior region of the maxilla is especially susceptible in edentulous patients. The flabby ridge lacks the firmness and stability required, leading dentures to become loose and unstable. Consequently, this instability can result in discomfort, speech and eating difficulties, and reduced quality of life for denture wearers. The flabby ridge often does not provide the necessary contour and resilience needed to establish an effective seal and maintain suction between the denture base and the underlying tissues. This compromises denture retention, making them susceptible to dislodgement during typical oral functions. Therefore, rehabilitating a completely edentulous patient with flabby tissue presents a formidable challenge for prosthodontists, as it undermines the retention, stability and support of complete dentures. Methods for managing flabby ridges encompass surgical removal, ridge augmentation, specialized impression techniques, balanced distribution of occlusal loads and implant therapy. Various impression techniques have been proposed to address the complexities of such cases. By carefully applying the principles of complete denture construction, a palliative treatment approach can be achieved. Special impressions often employ the window technique to capture a static impression of the flabby area, which introduces its own set of challenges. This innovative case report introduces a modified window technique that incorporates precise record transfer of the flabby ridge using tissue (blotting) paper. Specifically designed for the anterior mandibular flabby ridge, the technique employs a custom tray with a window positioned over the flabby tissues. A mucostatic impression material is utilized to minimize pressure on the flabby tissue, thereby reducing potential tissue distortion during the impression process. The procedure is executed in two steps: first, stable structures are recorded, followed by capturing the mobile tissues using light-body polyvinyl siloxane (PVS) elastomeric impression material within the window area. This method ensures an accurate record of the denture-supporting structures while maintaining the contour and details of the flabby tissues without displacement. Importantly, the technique is crafted for straightforward implementation by general dental practitioners within a primary dental care setting.

Efficacy of Ozone, UV Radiation, Herbal and Glutaraldehyde Method for Sterilisation of Elastomeric Impression Materials for Orthodontic and Prosthodontic procedures

ABSTRACT Objectives: The objectives of the current study was to evaluate the disinfection efficacy of ozone, ultraviolet (UV) radiation, herbal and glutaraldehyde method for sterilization of elastomeric impression materials Materials and Methods: Disinfection of elastomeric impression material was performed with each of the disinfection methods: ozone, UV radiation, herbal, and glutaraldehyde. Later microbiological analysis was performed and the colony-forming units were evaluated and compared. Results: The highest disinfection efficacy was found with glutaraldehyde, followed by ozone and UV radiation, and the least with neem herbal rinse. Intergroup comparison was highly significant Conclusion: Dry gaseous ozone and UV radiation can be used effectively for the disinfection of 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.

Accuracy of merging scans of definitive fixed prosthodontic impressions to obtain single, accurate digitized master casts.

Many elastomeric impressions sent to commercial laboratory dental technicians may include marginal defects. To fabricate accurate restorations, digital technology may be used to merge digital files of defective impressions into a single standard tessellation language (STL) file free of errors. This would save clinicians and patients time and may improve clinical care. The purpose of this study was to compare the accuracy of digital master casts reconstructed from merged STL files of defective impressions with the file of the original defect-free preparations. Ivorine teeth on a dentoform were prepared to receive a posterior fixed dental prosthesis (FDP) with complete coverage preparations. An impression was made in a stock tray using polyvinyl siloxane (PVS) impression material and an extraoral scanner (E3, 3Shape, Denmark) was used to digitize the impression; this was the reference cast. Wax was used to create defects on the buccal and lingual margins of the preparations. Fifteen PVS impressions were made of the FDP preparations with defects in the mesial and distal margins; another set of 15 PVS impressions was made of FDP preparations with defects in the buccal and palatal margins for a total of 30 impressions. All impressions were digitized using the same extraoral scanner (E3, 3Shape, Denmark). Corresponding STL files were paired and merged, and a master cast was created by eliminating the defects using the scanned data. This master cast was compared to the reference cast using reverse engineering software (Geomagic, Morrisville, NC, USA). The results were expressed as average errors and standard deviations in the master casts relative to the reference cast. To account for the presence of positive and negative values in the data set, in terms of errors, the root mean square (RMS) value was calculated for each sample. The mean average error in the sample was -0.4 μm. The average upper limit of 95% confidence interval was +36.5 μm, while the average lower limit of 95% confidence interval was -37.3 μm. The mean RMS of the errors found was 18.9 μm. The results of this study indicated that merging digitized definitive impressions to correct marginal defects resulted in master casts with a high level of accuracy relative to the reference cast.

An Evaluation of Retention of Complete Denture Bases Made with a “Modified Single-stage Impression” Technique Using a Heat-moldable Tray

Abstract Aim: Although most dental schools teach complete denture definitive impression techniques consisting of secondary impressions in border-molded custom impression trays, it has been found that later, graduates in clinical practice abandon this step because of its complexity and attempts to seek easier alternatives. To simplify two-stage techniques, single-step border molding with elastomeric impression materials and light-cured resin materials has gathered acceptance among clinicians. The study aims to evaluate the retention of record bases made with a modified single-stage impression technique that uses elastomeric impression material in a heat moldable tray with modeling compound as material for border molding. Settings and Design: This was an in vivo preliminary cohort study. Materials and Methods: Thirteen completely edentulous patients requiring complete dentures were included in the study. A traditional two-stage impression was made using custom trays fabricated over diagnostic casts and further border molding done with a modeling compound, and the final impression was made to use zinc oxide–eugenol impression material. Additionally, a modified single-stage impression technique using heat moldable impression trays was made. Master casts from each technique were made, and further record bases were made on each master cast. Wire loops were adapted on the palatal aspect of record bases. The retention of each record base was evaluated using a force gauge. Statistical Analysis: The Kolmogorov–Smirnov test was used to analyze the normality of variables and later Wilcoxon signed-rank test was applied. Results: The double-stage technique exhibited retention values in the range of 0.6–66.7 units, whereas the single-stage technique showed a range of 0.15–78.55. The tests showed no significant difference between double-stage and single-stage techniques (P > 0.05). Conclusions: The single-stage technique using heat moldable trays with elastomeric impression material and modeling compound as a material for border molding can produce denture retention compared to the conventional technique that uses a two-step impression technique. The use of the modified single-stage technique can additionally save an extra appointment for patients, although it is better to use such a technique as an advanced impression technique and not as a training technique for beginners or students, as the material cost is substantially higher than the conventional two-stage technique.

Evaluation of Elastic Recovery of Elastomeric Impression Materials Subjected to Various Disinfection Methods: An In-vitro Study

Evaluation of Elastic Recovery of Elastomeric Impression Materials Subjected to Various Disinfection Methods: An In-vitro Study

A SimpleImplant Guide for Infrazygomatic Bone Screw Placement with High Precision—A Clinical Innovation

Absolute anchorage systems like mini-implants, bone screws, and mini-plates have been a landmark evolution in the modern orthodontic world providing an added armamentarium in the hands of orthodontists to treat their patients with utmost efficiency. Unlike other systems, the extra radicular placement and limited surgical exposure make the bone screws such as infrazygomatic crest screws (IZC screws) superior, and to capitalize on these benefits, stability of the implant is vital that relies on their precise placement and angulation. Hence, this article presents a simple implant guide with elastomeric impression material for the precise positioning of IZC screws with utmost ease in fabrication.

Accuracy of impression scan bodies for complete arch fixed implant-supported restorations

Statement of problemDespite the extensive studies on and comparisons of different implant impression techniques for completely edentulous patients, studies on novel techniques that combine conventional impression making with digital scanning are lacking. PurposeThe primary aim of this study was to compare the accuracy of the impression scan body technique with conventional impression making and digital scanning for a completely edentulous mandibular arch. The secondary aim was to assess the relationship between different implant angulations and interimplant distances in relation to the recording accuracy. Material and methodsAn edentulous mandibular definitive cast (control) was designed with 5 implants placed at different angles and interimplant distances. Three recording techniques were tested: a conventional impression with splinted copings (conventional) (n=15), an impression scan body technique where impression scan bodies were attached to the splinted impression copings in a conventional elastomeric impression and then digitally scanned with an extraoral scanner (n=15), and an intraoral digital scanning technique (digital) (n=15). For comparison, the definitive cast and the conventional impression stone casts were digitized into standard tessellation language (STL) datasets using the extraoral scanner. The 3-dimensional (3D) deviations between the 3 test groups and the control were calculated by superimposing the STL datasets. The 3D deviations from the control were compared by using the Kruskal-Wallis test followed by the Dunn post hoc test (α=.05). The Mann-Whitney test was used to investigate the effect of implant angulation and interimplant distance on impression accuracy (α=.05). ResultsThe conventional splinted-coping impression technique showed a mean 3D deviation of 0.408 mm. The impression scan body and intraoral digital scan showed similar mean 3D deviations, 0.219 mm and 0.257 mm, respectively (P=.334). Both techniques showed significantly lower 3D deviations than the conventional technique (P<.001). Implants at an angle of 5 degrees and 10 degrees showed a statistically significant difference (P=.010) with mean 3D deviations of 0.340 mm and 0.396 mm, respectively. Implants with 5-mm and 10-mm interimplant distance showed a significant difference (P<.001) with mean 3D deviations of 0.301 mm and 0.423 mm, respectively. ConclusionsThe impression scan body technique is comparable with intraoral digital scanning for a completely edentulous arch. Increased implant angulation and increased interimplant distance significantly reduced the accuracy of implant impression making or scanning.

Quantification of flowability and hydrophilicity of elastomeric impression materials.

Abstract Introduction: Flowability and hydrophilicity are essential properties of accurate impressions and casts. Aim of study: This study aimed to quantify these characteristics of elastomeric impression materials. Material and Methods: A total number of eight impression materials, including vinyl polysiloxane (PVS), polyether (PE), and condensation silicone (CS) were thoroughly investigated in this study. The flowability of elastomers was proven with the shark fin test (SFT), and the hydrophilicity was determined with contact angle (CA) measurements. Results: The shark fins’ (SF) of VPSs presented 11.57 mm (SD 3.49), while the PE 11.37 mm (SD 5.06) and CS 8.1 mm average values. Some of the products showed better flowability. Based on 128 measured CAs, the examined polyethers had the lowest CAs which indicate good hydrophilicity. Conclusions: A good performance of an impression material in one of the involved tests (SFT and CA) does not mean a similar result in the other analysis. All investigated impression materials could be considered hydrophilic as their CA was lower than 90°. The SFTs of light-bodied VPSs and PEs suggest reliable use of them in dental practice.

A Comparative Evaluation of Dimensional Change of Addition Reaction Elastomeric Impression Material After Disinfecting With 1% NaOCL and 3% H2O2: An in Vitro Study

Elastomeric impression materials are most commonly used impression materials in clinical practice for treating partially edentulous patient. After making impression it needs to be sterilized properly to minimize the risk of cross infection. Dimensional stability and accuracy of an impression after chemical disinfection by using different disinfectants are crucial for the accuracy of final prosthetic restoration. Until 1991 the recommended procedure for disinfection of impression was rinsing under running water with which only 40% of bacteria, virus, and fungi were removed and potential for transmission of microorganism remained there. Now a days most clinically used disinfection solutions are 3% hydrogen peroxide and 1% sodium hypochlorite. These two solutions are more effective to diminish microorganisms from the impression surface without altering dimensional stability.

Non-surgical periodontal treatment for black triangle

Objective: This case report aims to introduce the black triangle therapy in Miller’s Class IV gingival recession. Methods: The patient complained of spacing between the upper and lower teeth causing food accumulation, “long teeth”, and receding gums which were unaesthetic during speaking. Clinical examination of the maxillary and mandibular anterior revealed Miller Class IV gingival recession, large black triangles, no tooth mobility nor pocket probing, and no gingival inflammation signs. Based on clinical and radiograph examination, nonsurgical therapy using gingival mask was the best option. Nonsurgical therapy using gingival mask was made using indirect technique with an elastomeric impression. An extra-soft soft liner was chosen for gingival mask materials. Results: The black triangle was covered. The “long teeth” appearance and hypersensitivity were reduced. Conclusion: Gingival masks is a good and predictable nonsurgical treatment option for treating black triangle in Miller Class IV gingival recession.

Effect of Gingival Hemostatic Agents on the Surface Detail Reproduction and Dimension Stability of Three Elastomeric Impression Materials.

This study aimed to evaluate the effects of aluminum chloride based hemostatic agents on the surface detail reproduction and dimension stability. Three impression materials were investigated after contaminated with three commercial astringents with different concentration of aluminum chloride. The specimens from three impression materials were fabricated with a stainless-steel mold that followed the American Dental Association specification no.19. The mold was preliminarily contaminated with three hemostatic agents racestyptine, Dryz, and Expasyl™-and 80 specimens from each impression material-polyvinylsiloxane (PVS), polyether, and polyvinylsiloxane ether (PVSE), were fabricated and subjected to each astringent. The surface detail reproduction was examined using a stereomicroscope at 4x magnification, and the dimensional stability was analyzed at 24 hr with a measuring microscope. The surface detail data were statistically analyzed with Fisher's test at a significance level of 0.05. The dimensional stability data were analyzed using two-way ANOVA and Tukey's test at a significance level of 0.05. Aluminum chloride hemostatic agents can affect the surface detail reproduction of impression materials differently (p < 0.05). Thus, the first null hypothesis was rejected. PVS showed the highest percentage of satisfactory surface detail regardless of the hemostatic agent used in this study. PVSE showed a reduced percentage of satisfactory surface detail when the concentration of aluminum chloride was high. The three hemostatic agents affected the dimensional stability of each material differently (p < 0.05). Therefore, the second null hypothesis was also rejected.

Modified feeding plate for a one-month-old infant with Pierre Robin sequence: A case report

Pierre robin sequence is characterized by the triad of mandibular micrognathia, ‘U’ shaped cleft palate, and glossoptosis. Infants with this condition usually present with airway obstruction and feeding difficulties. This in turn leads to low weight and nutritional deficiencies which might delay the surgical intervention for the same. This case report describes a one-month-old infant with Pierre Robin sequence presenting with feeding difficulty and nasal regurgitation due to a ‘U’ shaped cleft palate. Elastomeric impression followed by fabrication of feeding plate with auto-polymerizing resin was done. Additional ‘S-shaped’ retentive arms were provided from the intra-oral to extra-oral side wire to provide additional retention and to prevent injury to both the child and parent while feeding. Early insertion of a feeding plate helps to prevent nasal regurgitation, to gain weight, and to guide the growth of the mandible in a child with Pierre Robin Sequence.