Elastomeric Impression Research Articles

Prosthetic rehabilitation of a serving soldier with custom made ocular prosthesis

Eyes are the prominent organs of the facial structure and first feature to be noticed during interactions. Loss of an eye can be because of various reasons like congenital defects, traumatic injury, road traffic accidents, gun shot wounds, or malignant tumors.1 Gun shot wounds or blast injuries are the most common causes for the loss of eyes in armed forces personnel. The disfigurement associated with the loss of an eye can cause significant physical, psychological and emotional problems.2 Prosthetic rehabilitation of such patients with ocular prosthesis will improve patient's quality of life and increase their confidence. This kind of rehabilitation is more challenging because we try to replace mobile ocular tissue with a non-mobile prosthesis. Ocular prostheses are either ready-made or custom made. Ready-made ocular prosthesis does not fit properly to the ocular bed and movement of the prosthesis does not correspond to the movement of the ocular bed. The close adaptation of the ocular prosthesis to the soft tissues of the ocular bed enhances comfort of the patient and results in physiological movement of prosthesis corresponding to the movement of the ocular bed. Intimate contact of the prosthesis to the ocular bed prevents the collection of the mucus and debris below the prosthesis. This kind of contact of the prosthesis with the ocular bed can be achieved only with the custom ocular prosthesis.3 A clinical report of a serving soldier who had sustained gun shot wound in counter insurgency operation, rehabilitated with custom made ocular prosthesis is presented. The improvised technique of fabrication of the prosthesis using addition silicone elastomeric impression material is also described.

The Effectiveness of Using Pulpotec® in Treatment of Pulpitis by Pulpotomy of Vital Deciduous Molar and Vital Immature Permanent Molar

Aims: To evaluate the effect of two types of disinfectant solutions(2% alkaline glutaraldehyde, 1% sodium hypochlorite) in wettability of three types of elastomeric impression materials (light body) which are used in crown and bridge restorations at different times of immersion. Materials and me-thods: Three types of elastomeric impression materials (light body) were formed on a flat acrylic resin block and allowed to set(five specimens of each impression material was done for each immersion time(15,30 and60 minutes)of each disinfectant solution in addition to control groups). The wettability is indicated by measuring the contact angle of aqueous solution of CaSO4 on surface of cured impres-sion materials. Results: indicated no significant effect of immersion times on wettability of three types of impression materials. The hydrophilic type produce high wettability. Conclusions: The disinfectant solutions have different effects on each impression material. Sodium hypochlorite has the greatest beneficial effect on wettability

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

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

Qualitative and quantitative three-dimensional accuracy of a single tooth captured by elastomeric impression materials: An in vitro study

The accuracy of impressions has been described in 1 or 2 dimensions, whereas it is most desirable to evaluate the accuracy of impressions spatially, in 3 dimensions. The purpose of this study was to demonstrate the accuracy and reproducibility of a 3-dimensional (3-D) approach to assessing impression preciseness and to quantitatively comparing the occlusal correctness of gypsum dies made with different impression materials. By using an aluminum replica of a maxillary molar, single-step dual viscosity impressions were made with 1 polyether/vinyl polysiloxane hybrid material (Identium), 1 vinyl polysiloxane (Panasil), and 1 polyether (Impregum) (n=5). Corresponding dies were made of Type IV gypsum and were optically digitized and aligned to the virtual reference of the aluminum tooth. Accuracy was analyzed by computing mean quadratic deviations between the virtual reference and the gypsum dies, while deviations of the dies among one another determined the reproducibility of the method. The virtual reference was adapted to create 15 occlusal contact points. The percentage of contact points deviating within a ±10 µm tolerance limit (PDP(10) = Percentage of Deviating Points within ±10 µm Tolerance) was set as the index for assessing occlusal accuracy. Visual results for the difference from the reference tooth were displayed with colors, whereas mean deviation values as well as mean PDP(10) differences were analyzed with a 1-way ANOVA and Scheffé post hoc comparisons (α=.05). Objective characterization of accuracy showed smooth axial surfaces to be undersized, whereas occlusal surfaces were accurate or enlarged when compared to the original tooth. The accuracy of the gypsum replicas ranged between 3 and 6 µm, while reproducibility results varied from 2 to 4 µm. Mean (SD) PDP(10)-values were: Panasil 91% (±11), Identium 77% (±4) and Impregum 29% (±3). One-way ANOVA detected significant differences among the subjected impression materials (P<.001). The accuracy and reproducibility of impressions were determined by 3-D analysis. Results were presented as color images and the newly developed PDP(10)-index was successfully used to quantify spatial dimensions for complex occlusal anatomy. Impression materials with high PDP(10)-values were shown to reproduce occlusal dimensions the most accurately.

Effect of Chemical Disinfection on Dimensional Stability of Polyether Elastomeric Impression Material

Polyether is one of a commonly used material for making impressions in prosthetic dentistry because of its properties like, excellent dimensional stability and low polymerisation shrinkage. Impressions should be properly disinfected before sending to laboratory, but disinfection by immersion may cause dimensional changes because of hydrophilic nature of polyether. So this study was designed to evaluate the effect of disinfection on dimensional stability of polyether impression.

Surface detail reproduction under simulated pulpal pressure: A 3-dimensional optical profilometer and scanning electron microscopy evaluation

It is not clear whether more hydrophilic impression materials are better able to copy and transfer dentin surface detail than less hydrophilic ones. The purpose of this study was to evaluate the reproduction of dentin surface detail by means of hydrophobic and hydrophilic elastomeric impression materials under simulated pulpal pressure and their ability to transfer surface detail onto casts produced from such impressions. The wettability of the impression materials (n=8) was determined by contact angle measurement with an evolution period of 135 seconds. Dentin moisture was provided by means of pulpal pressure simulation, and objective analyses were performed by measuring the average roughness value (Ra) with a 3-D optical profilometer (n=10). One specimen from each group was analyzed with scanning electron microscopy. Contact-angle values were analyzed with a repeated measures ANOVA, and detail reproduction was tested with 3-way ANOVA (α=.05). The Bonferroni correction was used to control Type I error for follow-up analyses. Contact angle measurements revealed significant differences depending on the impression material used and time of the measurement (P<.001). The Ra values of the hydrophilic impression materials, which were made from dry specimens, and the pulpal pressure simulated dentin surfaces did not differ from the dentin surfaces (P>.013). The hydrophobic impression material showed similar detail reproduction ability in a dry field, but loss of detail (evaluated subjectively) and increased roughness values (evaluated objectively) were recorded in a moisturized field (P=.004). Polyurethane-based cast material successfully reproduced the surface texture (P≥.006), whereas Type IV gypsum material was unable to reproduce this texture to the same extent. The hydrophilic impression materials tested showed similar ability to reproduce detail under simulated pulpal pressure. Polyurethane-based cast material successfully reproduced the surface texture.

A Technique for Impressing the Severely Resorbed Mandibular Edentulous Ridge

Patients presenting with severe resorption of the residual alveolar ridges are relatively common today in both private practices and teaching institutions. The severely resorbed mandibular ridge is more challenging to impress than is the maxillary ridge. Accurately capturing the denture-bearing surface in its entirety is crucial to providing the patient with a functionally successful prosthesis. This article presents a technique to overcome the difficulties encountered in impressing the severely resorbed mandibular ridge using elastomeric impression materials and a modified special custom tray.

A comparative study of the clinical efficiency of chemomechanical caries removal using Carisolv®and Papacarie®- A papain gel

The purpose of this study was to compare the clinical efficiency of chemomechanical caries removal using Carisolv and Papacarie - a papain gel. The Carisolv system for caries removal, consisting of a solvent gel and a specially designed hand instrument, was compared to Papacarie - a papain gel. The outcome variables were: time taken for complete caries removal and volume of carious tissue excavated. Forty patients in the age-group of 20-40 years, having Black's class I dentinal caries with cavity entrance size of ≥3 mm in the molars, were enrolled for the study. The time taken for the complete removal of caries was measured using a stopwatch. Pre- and post-excavation single-step putty/wash elastomeric impression was recorded using addition silicone impression material. Subsequently, casts were poured and measured under a traveling microscope. The total volume of caries excavated was computed using the formula π (d/2)² h. The difference between the two groups in clinical efficiency and volume excavated was statistically analyzed using the Student's unpaired 't' test. The time for caries removal with Carisolv and Papacarie were, respectively, 11.67 ± 3.25 minutes and 10.48 ± 2.96 minutes (P>.05). The mean volume of carious tissue removed with Papacarie (135.99 ± 66.43 mm ³ ) was higher than that with Carisolv (126.33 ± 53.56 mm ³ ); however, the difference was not significant. Carisolv and Papacarie have similar clinically efficiency as chemomechanical agents for dentinal caries removal.

Effect of Different Impression Techniques on the Dimensional Accuracy of Impressions using Various Elastomeric Impression Materials: An in vitro Study

Production of exemplary crowns and fixed partial dentures depends upon the usage of impression material and its technique of usage that accurately reproduces prepared teeth and their relationship to the adjacent oral structure. To evaluate the linear dimensional accuracy of the elastomeric impressions using various impression techniques using different combinations of viscosities of impression materials. Crown preparation was done in a dentulous acrylic resin denture base model with six natural teeth embedded into it was made to represent the dentulous maxillary arch. A total of 55 impressions were obtained and poured in die stone using various impression techniques with different combinations of viscosities of impression materials. Among the six techniques used, the heavy body light body two-step technique using custom tray showed the least distortion which was closely followed by the putty wash two-step technique with 2 mm spacer using stock tray. The study revealed that the heavy body light body two-step technique with custom tray provided the best results. Dimensional accuracy of impressions is very much required for precisely fitting of prosthesis. This study may be helpful to select the technique and materials as per clinical requirement of accuracy of impressions.

Effect of different palatal vault shapes on the dimensional stability of glass fiber-reinforced heat-polymerized acrylic resin denture base material

The aim of this study was to determine the effect of different palatal vault shapes on the dimensional stability of a glass fiber reinforced heat polymerized acrylic resin denture base material. Three edentulous maxilla with shallow, deep and medium shaped palatal vaults were selected and elastomeric impressions were obtained. A maxillary cast with four reference points (A, B, C, and D) was prepared to serve as control. Point (A) was marked in the anterior midline of the edentulous ridge in the incisive papillary region, points (B) and (C) were marked in the right and left posterior midlines of the edentulous ridge in the second molar regions, and point (D) was marked in the posterior palatal midline near the fovea palatina media (Figure 2). To determine linear dimensional changes, distances between four reference points (A-B, A-C, A-D and B-C) were initially measured with a metal gauge accurate within 0.1 mm under a binocular stereo light microscope and data (mm) were recorded. No significant difference of interfacial distance was found in sagittal and frontal sections measured 24 h after polymerization and after 30 days of water storage in any of experimental groups (P>.05). Significant difference of linear dimension were found in all experimental groups (P<.01) between measurements made 24 h after polymerization of specimens and 30 days after water storage. Palatal vault shape and fiber impregnation into the acrylic resin bases did not affect the magnitude of interfacial gaps between the bases and the stone cast surfaces.

A Comparative Study to Determine the Wettability and Castability of Different Elastomeric Impression Materials

The aim of this study was to determine the wettability of different hydrophilic and hydrophobic elastomeric impression materials and the gypsum castability. The wettability was evaluated by determining the contact angles of different elastomeric impression materials. The contact angle was determined by placing a drop of aqueous solution of calcium sulfate dihydrate on the flat surface of impression material and specimens were measured using a profile projector. Gypsum castability was determined by counting the number of voids formed in the die stone cast made from the impressions of a aluminum die. The voids were counted using an diopter magnifying lens. Polyether, different viscosities of polyvinyl siloxane, and condensation silicone impression materials exhibited low contact angle values and least number of voids in the die stone cast when compared with polysulfide impression material. There was significant correlation between the contact angle and voids formed in the die stone casts when fabricating die stone casts from various elastomeric impression material impressions. Accurate reproduction of prepared tooth or edentulous arch is of clinical importance in the fabrication of a fixed or removable prosthesis. Inaccuracies in the replication processes will ultimately have an adverse effect on the fit and adaptation of final restoration. The interaction is determined in part by hydrophilic and hydrophobic nature of the elastomeric impression material. Inadequate wetting of an impression results in voids in the stone casts.

The Influence of Tray Space and Repeat Pours on the Accuracy of Monophasic Polyvinylsiloxane Impression

While literature demonstrates that the optimum accuracy is obtained with the custom trays, the use of stock trays for elastomeric impressions appears to be popular in general practice. The aim of the study was to evaluate the effect of thickness of impression material on the dimensional accuracy of impressions made from monophasic polyvinylsiloxane impression material. This study also studies the dimensional stability of the impressions poured at different time intervals. A metal model simulating two abutment teeth was fabricated along with reference lines inscribed on them. Custom impression trays were fabricated with spacer thickness of 2, 4 and 6 mm. impressions were made using monophasic polyvinyl siloxane impression material. The impressions were poured and stone models were obtained. The dimensional accuracy of the impressions were determined indirectly by measuring the dimensional changes of the recovered stone models. The dimensional stability was also evaluated by pouring the impressions at time intervals of 1 hour, 24 hours and 7 days. The obtained data was statistically analyzed. The results of the study indicated that the impressions made from 2 and 4 mm tray space produced more accurate stone models when compared to 6 mm tray space. There was no significant deviation in the mesiodistal and buccolingual dimensions when impressions were made using impression trays with 2, 4 and 6 mm tray spacers. There was a significant decrease in interabutment distance (p = 0.001) and height of the abutment (p = 0.024) when impressions were made using impression trays with a tray space of 6 mm. There were no significant differences found among the stone models obtained from 1 hour, 24 hours and 1 week pour times. The mesiodistal and buccolingual dimensions of the abutments were not affected by the variations in thickness of impression material. There was a decrease in the height of the abutment which was clinically not significant. As the thickness of the impression material increased, the interabutment space decreased, which is a factor of concern when impressions are made for fixed partial dentures. When monophasic polyvinylsiloxane is used as the impression material, stock trays can be used for making impressions for individual castings.

Modified cytotoxicity evaluation of elastomeric impression materials while polymerizing with reduced exposure time

Objective. Cytotoxicity evaluation is an important step in biocompatibility assessment of dental impression materials. Previously, cytotoxicity evaluations were carried out on already set (‘set’) impression materials for contact time or extraction time of 24 h or longer in duration. However, clinically, dental impression materials are in contact with oral tissue while they are being set (‘polymerizing’), for no longer than 10 min. Hence, the aim of this study was to investigate the difference in results between ‘polymerizing’ and ‘set’ forms of impression materials as well as the difference in results between longer duration of contact or extraction time (12 or 24 h) and shorter duration of time (15 or 30 min). Materials and methods. Seven dental impression materials of different chemical compositions were tested. Two commonly used in vitro tests were used—test on extraction and test by direct contact. Both ‘polymerizing’ and ‘set’ forms of impression materials were used with different durations of extraction and contact (15 min, 30 min, 12 h and 24 h). Results. There were significant (p < 0.05) differences of cell viability and cell proliferation between the ‘polymerizing’ and ‘set’ impression materials. Also, significant (p < 0.05) differences were noted with variance in duration of time. Conclusion. In light of the results, it is recommended to use a ‘polymerizing’ state of dental impression material for cytotoxicity evaluation, with 15 or 30 min of contact between cell and dental impression materials and an extraction time of 15 or 30 min that is more reflective of clinical situations.

The Influence of Verification Jig on Framework Fit for Nonsegmented Fixed Implant‐Supported Complete Denture

The purpose of this retrospective study was to assess if there was a difference in the likelihood of achieving passive fit when an implant-supported full-arch prosthesis framework is fabricated with or without the aid of a verification jig. This investigation was approved by the University of Rochester Research Subject Review Board (protocol #RSRB00038482). Thirty edentulous patients, 49 to 73 years old (mean 61 years old), rehabilitated with a nonsegmented fixed implant-supported complete denture were included in the study. During the restorative process, final impressions were made using the pickup impression technique and elastomeric impression materials. For 16 patients, a verification jig was made (group J), while for the remaining 14 patients, a verification jig was not used (group NJ) and the framework was fabricated directly on the master cast. During the framework try-in appointment, the fit was assessed by clinical (Sheffield test) and radiographic inspection and recorded as passive or nonpassive. When a verification jig was used (group J, n = 16), all frameworks exhibited clinically passive fit, while when a verification jig was not used (group NJ, n = 14), only two frameworks fit. This difference was statistically significant (p < .001). Within the limitations of this retrospective study, the fabrication of a verification jig ensured clinically passive fit of metal frameworks in nonsegmented fixed implant-supported complete denture.

An in Vitro Study to Evaluate the Effect of Two Disinfectant Solutions on Wettability of Three Elastomeric Impression Materials

An in Vitro Study to Evaluate the Effect of Two Disinfectant Solutions on Wettability of Three Elastomeric Impression Materials

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

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

Dimensional accuracy of stone casts made by a monophase impression technique using different elastomeric impression materials

Impression taking is a critical step in the process of producing successful crowns and fixed partial dentures in oral rehabilitation, and the impression material is an important factor related to clinical success. Aim: The aim of this in vitro study was to assess and compare the dimensional accuracy of stone casts made from a monophase technique using 10 elastomeric impression materials. Methods: First, a stainless steel model with reference points in the teeth 33, 43, 37, and 47 was used to obtain the impressions. The distances were measured among teeth 33-43, 37-47, 33-37, and 43-47. For the impression technique, acrylic resin trays were made with an internal relief of approximately 2 mm. Specific adhesives for each material were used in the custom trays. Tray detachment movement was standardized by pneumatic equipment. After the impression procedures and obtaining of samples, the stone casts were observed in a measuring microscope at 30x magnification. Data recorded for each distance were analyzed statistically by one-way analysis of variance and Tukey’s test at 5% significance level. Results: Stone casts made with elastomeric impression materials showed statistically significant (p<0.05) differences when the dimensional accuracy values were compared. The order for the highest to lowest accuracy for the types of impression materials was as follws: polyvinylsiloxane (PVS), polyether, polysulfide and polydimethylsiloxane (PDMS). Conclusions: PVS were the most dimensionally accurate impression materials, and the PDMS showed the worst results of dimensional accuracy.

Morphological Pattern of Palatal Rugae in Children of Davangere

The aim of this study was to identify and compare the rugae pattern between males and females of two different communities in the city of Davangere, Karnataka, India, which may be an additional method of identification in cases of crimes or communal riots. Elastomeric impressions of the maxillary arch of 100 selected children were made; casts were poured in Type IV stone. The method of identification of rugae pattern followed was that of Lysell and Thomas and Kotze, which includes the number, shape, direction, and unification of rugae. The study revealed no significant difference in the total number or length of rugae between the two communities and sexes. However, with regard to shape and unification, females showed a significantly higher diverging rugae type while males had a significant number of circular and converging type of rugae. Also, discrimination function analysis allowed a moderate differentiation of the population. Hence, the rugae pattern can be an additional method of differentiation in conjunction with the other methods such as visual, fingerprints, and dental characteristics in forensic sciences.

Prosthodontic considerations designed to optimize outcomes for single‐tooth implants. A review of the literature

The aim of this study was to review the literature on the restoration of single-tooth implants, and to develop evidence-based conclusions to optimize aesthetic, biologic and patient-related outcomes. An electronic and hand search was conducted using the search terms 'dental implants, single-tooth; dental restoration, temporary; dental impression materials; dental impression technique; dental prosthesis, implant-supported; dental prosthesis design; dental abutments; dental occlusion; maintenance; survival; and survival analysis'. Resultant titles were screened, and full text was obtained where relevant. The authors selected the most appropriate articles, giving preference to systematic reviews and long-term, patient-based outcome data. Thirty-nine articles were selected and critiqued by the authors. There was strong suggestion by several authors that peri-implant soft tissue aesthetics can be sculpted through provisional restoration contour, but there are no clinical outcome studies to define or support this claim. Laboratory studies demonstrate that pick-up type impression copings in conjunction with elastomeric impressions are the most accurate means for transferring implant position to a dental cast. Laboratory and finite-element analysis studies suggest implants with an internal-type connection show improved stress distribution, but supportive clinical data are lacking. The authors of this review favour a screw-retained prosthesis for retrievability. Clinical and histological studies show that gold, titanium and zirconia ceramic abutment materials exhibit excellent biological responses, although there is insufficient data on the clinical service provided by zirconia as an implant-substructure material. The literature does not associate any particular occlusal scheme with superior clinical outcomes. Implant-borne single crowns offer comparable clinical service to tooth-borne fixed dental prostheses. However, single-tooth implant restorations are associated with an increased incidence of biological and technical complications.

Clinical success rates for polyether crown impressions when mixed dynamically and statically

The purpose of this study is to compare success rates of dual-viscosity impressions for two types of mixing techniques of the polyether elastomeric impression material. Additionally, influencing parameters on the success rates should be evaluated. The expectation was that there would be no difference between the success rates for the two mixing techniques. Two centres enrolled 290 subjects (727 teeth) into the trial. Patients were randomized for the two types of mixing techniques. One step, dual-viscosity impressions were made with either statically mixed Impregum Soft tray material (SAM) or dynamically mixed Impregum Penta H DuoSoft (DMM). Low viscosity Impregum Garant L DuoSoft was used for both groups. Gingival displacement involved the use of two braided cords. Full-arch trays were used exclusively. Both critical defects and operator errors were assessed for the first impression taken by trained dentists. The primary outcome was impression success. For comparison of the two mixing techniques, the odds ratio for success and the corresponding one-sided 95% confidence interval was calculated by a logistic regression model. To account for the dependence between several teeth within one patient, the method of general estimating equations was used. The overall impression success rate was 35.4%. Both mixing techniques showed equal success rates indicated by an OR of 1.0 and a lower limit of the one-sided 95% confidence interval of 0.71. Using this result to develop the corresponding interval for the difference, it could be shown that the success rate using SAM was at most 8.2% lower than that when using DMM with a probability of 95%. Multivariate logistic regression analysis of other potential influencing factors showed position of finish line (p = 0.008, supra compared to mixed), blood coagulation disorder (p = 0.021) and the level of training of the clinician (student vs dentist, p=0.008) to have an independent influence on the success rate. Dynamic mechanical mixing and the new static mixing of polyether tray material showed nearly equal success rates in the study even though success rates were comparatively low (DMM, 35.3%; SAM, 35.4%).