Linear Dimensional Stability Research Articles

An In vitro Study Comparing Dimensional Stability of Four Types of Interocclusal Recording Material

ABSTRACT Background and Objectives: Interocclusal recording materials should have high dimensional stability for accurate articulation. The aim of this in vitro investigation is to assess and compare the linear dimensional stability of interocclusal recording materials over time. Methods: Polyvinylsiloxane, polyether, bisacryl and bite registration wax were used in the study. The test used a mold according to the American Dental Association (ADA) specification number 19. A total of 40 samples were collected, and each group consisted of 10 samples. The dimensional changes in the samples after 1, 24, 48, and 72 h were measured using an optical microscope equipped with a micrometer device. Results: Each sample had five measurements taken at different times, and the mean of those readings was used to calculate the dimensional change and compare it to the initial measurement made on the die. ANOVA and the Tukey HSD test for repeated measurements were used to examine the data. The average percentage dimensional change over time 1) Group A: 1, 24, 48, and 72 h; 2) Group B: 1, 24, 48, 72 h; 3) Group C: 1, 24, 72 h; 4) Group D1, 24, 48, 72 h; and so on. Interpretation and Conclusion: Both material and temporal considerations impact on linear dimensional stability. The most dimensionally stable material was discovered to be polyvinylsiloxane, followed by polyether, bisacryl, and bite registration wax.

Dimensional Stability and Compressive Resistance of Three Interocclusal Record Materials: A Comparative In Vitro Study.

Accurate interocclusal records are crucial for a successful prosthetic treatment as they ensure the correct replication of a patient's jaw movements and relationships. The dimensional stability and compressive resistance of interocclusal record materials are essential factors influencing the quality of the final prosthesis. This study aims to evaluate and compare the dimensional stability and compressive resistance of three commonly used interocclusal recording materials: Ramitec (polyether; 3M ESPE, St. Paul, MN), Bona-Bite (polyvinyl siloxane; DMP Dental, Markopoulo, Greece), and O-Bite (polyvinyl siloxane; DMG Dental, Hamburg, Germany). An in vitro study was conducted using 108 samples prepared from three interocclusal record materials: Ramitec, Bona-Bite, and O-Bite, with each material tested at three different thicknesses (2, 4, and 6mm). A master stainless steel die was used to create the samples. The compressive resistance of each material was measured by applying a static load of 25N using a universal testing machine for one minute. Linear dimensional stability was assessed by comparing the diameters of the samples before and after compression using a vernier caliper. Bona-Bite exhibited the highest compressive resistance with mean values of 0.315±0.066 (6mm), 0.319±0.065 (4mm), and 0.306±0.065 (2mm). It also showed the least linear dimensional change, with mean values of 0.073±0.040 (6mm), 0.105±0.057 (4mm), and 0.080±0.036 (2mm). In comparison, Ramitec and O-Bite demonstrated lower compressive resistance and higher dimensional changes. Statistical analysis revealed significant differences between Bona-Bite and the other materials in both compressive resistance and dimensional stability. Bona-Bite (polyvinyl siloxane) outperformed Ramitec (polyether) and O-Bite (polyvinyl siloxane) in terms of compressive resistance and dimensional stability. Therefore, Bona-Bite is recommended for use in interocclusal recording to achieve more accurate and reliable prosthetic outcomes.

Evaluation of the Linear Dimensional Stability of CAD/CAM Milled, 3-D Printed, and Heat-cured Denture Base Polymers Subjected to Thermocycling and Immersion in Artificial Saliva: An In vitro study

Evaluation of the Linear Dimensional Stability of CAD/CAM Milled, 3-D Printed, and Heat-cured Denture Base Polymers Subjected to Thermocycling and Immersion in Artificial Saliva: An In vitro study

Comparison of Linear Dimensional Stability among Three Different Types of Interocclusal Recording Materials: An In-vitro Study

Introduction: In routine dental practice, clinicians often face difficulty in selecting accurate interocclusal recording materials due to the introduction of numerous options in the market. Therefore, it is crucial to choose the appropriate material and use it correctly for the success of any prosthesis. Aim: To evaluate and compare the linear dimensional stability of three different types of interocclusal recording materials: polyvinyl siloxane bite registration paste (orangebite), polyether bite registration paste (ramitec), and bite registration wax (aluminium filled). Materials and Methods: An in-vitro study was conducted in the Department of Prosthodontics and Crown and Bridge, with microscopic evaluation performed at the Department of Oral and Maxillofacial Pathology and Microbiology at Maratha Mandal’s NGH Institute of Dental Sciences and Research Centre, Belagavi, Karnataka, India in September 2020 for a period of four days. A stainless steel die was used to make impressions, and materials were manipulated according to the manufacturer’s instructions. A total of 30 samples (10 for each material) were created. Three minutes after the respective setting time of each material, discs were separated from the die. The distance between two parallel lines was measured using a stereomicroscope at different time intervals: one hour, 24 hours, 48 hours, and 72 hours. Statistical analysis was performed using Analysis of Variance (ANOVA) and the Mann-Whitney test. Results: In the intragroup comparison of dimensional changes at different time intervals, all three materials showed statistically insignificant results (p>0.05). However, statistically significant results (p≤0.05) were found when comparing the materials at different time points. Polyether bite registration material exhibited better dimensional stability than polyvinyl siloxane and bite registration wax at one hour, 24 hours, 48 hours, and 72 hours. Conclusion: Polyether demonstrated superior dimensional stability compared to polyvinyl siloxane and bite registration wax. The dimensional stability was influenced by both the material used and the duration of time

The effect of sodium hypochlorite disinfectant on the linear dimensional stability of alginate impression material.

Objective: To compare changes, in linear dimension of Alginate impression by disinfection with immersion in 0.525% Sodium Hypochlorite solution and no disinfection. Study Design: Randomized Control Trial. Setting: Department of Prosthodontics, Punjab Dental Hospital Lahore. Period: April 2018 to September 2018. Material & Methods: Sixty alginate impressions were made of a stainless steel die and were randomly divided into two groups. The 30 control group impressions were poured only after rinsing with tap water, whereas the 30 experimental group impressions were first immersed in 0.525% Sodium Hypochlorite solution for 10 minutes and then poured after rinsing with tap water. The distance between two engraved lines C and D on die were measured in the casts of both groups. Results: The mean difference of mean dimensional changes between both methods was 0.01mm. Conclusion: The disinfection of the alginate impression material by immersion in 0.525% Sodium Hypochlorite solution does not cause significant effect on dimensional stability of alginate impression material.

Evaluation of Linear Dimensional Stability of Monomethacrylate-based Dental Polymer Containing a Novel Tricyclic Diacrylate Cross-linker Using a Novel Surface-level Index Technique

Evaluation of Linear Dimensional Stability of Monomethacrylate-based Dental Polymer Containing a Novel Tricyclic Diacrylate Cross-linker Using a Novel Surface-level Index Technique

Dimensional stability of stored extended-pour irreversible hydrocolloids materials

The purpose of this study was to evaluate the linear dimensional stability of four extended-pour irreversible hydrocolloids (EPIHs). Material and Methods: Five samples per material (Cavex ColorChange, Cavex Orthotrace, Jeltrate Plus, and Orthoprint) were prepared following the manufacturers’ instructions. The samples were prepared using a cylindrical matrix coupled with a nylon-polyamide ring. Two parallel, 25-mm equidistant lines were made on its surface following ANSI/American Dental Association (ADA) Specification 18 for plaster reproducibility and compatibility and Specification 19 for linear dimensional change. The samples were stored in an environment with a relative humidity of 70% (± 3) and temperature of 28°C (± 2). Photo images were obtained using a digital camera to record images for 120 hours, with a standardized distance of 80cm between the lens and the specimen. Adobe Photoshop CS3 software was used for the measurement of the recorded images. The measurements refer to the equivalent distance between the two parallel lines printed on the samples. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey’s test for multiple comparisons between the means of the groups. Results: There was no statistically significant difference (p > 0.05) when EPIHs were compared at the same time of evaluation. Orthoprint, Cavex Orthotrace, and Cavex Colorchange presented with least dimensional stability up to 24 hours (p > 0.05) of storage, followed by Jeltrate Plus (48 hours). Conclusions: Storage of EPIHs for more than 24 hours for Cavex ColorChange and 48 hours for others EPIHs studied produces significant dimensional changes in the impressions stored at a humidity of 70% (± 3) and temperature of 28°C (± 2). Extended storage times produce large dimensional changes.

Comparative study on linear dimensional stability between condensation silicones and addition silicones using the sandwich technique

Purpose: The study refers to the linear dimensional stability of silicone elastomers by comparing silicones with condensation curing and silicones with addition curing. Materials and Methods: The present research is represented by an "in vitro" study, interested only in the evolution of the dimensional stability of silicone elastomers in terms of the material used. A control model was created made of a hard plastic with which the existing samples were compared. The photographic documentation of each study model was made, in order to later document the differences obtained compared to the control model. Results: All photos taken were analyzed using a photo analysis software (UTHSCSA ImageTool, version 3.0). The measurement results were recorded in tables and statistically analyzed. Conclusions: The ideal material in terms of dimensional stability is represented by addition cure silicone.

EVALUATION OF LINEAR DIMENSIONAL STABILITY OF BD IMPRESS AND NEXUS MEDODENT THERMOPLASTIC IMPRESSION MATERIALS – AN IN VITRO COMPARATIVE STUDY

Aim: To evaluate and compare the linear dimensional stability of two commercially available BD IMPRESS and NEXUS MEDODENT thermoplastic impression materials. A total of 90 samples in which 45 s Methodology: amples of BD Impress and Nexus medodent impession materials were used for evaluation of linear dimensional stability of these newly introduced thermoplastic impression materials. The samples were rst checked under toolmaker microscope for reproduction of three parallel lines x,y,z. The measurements were made on the samples at 0 (within 24 hours), 7th and 14th day respectively to assess the linear dimensional stability. According to the study conducted and results obtained, it Result: was concluded that NEXUS MEDODENT was superior in linear dimensional stability on comparison with BD IMPRESS impression material Conclusion: On comparison with BD impress, nexus medodent impression material was superior in terms of linear dimensional stability. There is a need for further studies to know about other properties of these thermoplastic impression materials to enhance knowledge and for clinical application as indicated by manufacturers.

Effects of disinfectant solutions incorporated in dental stone on setting expansion, compression and flexural strength of dental models

Purpose of the study: The aim of the study is to analyze the way the disinfectants embedded in the plaster affect the setting linear dimensional stability, flexural and compressive strength of dental stone models. Material and Methods: Samples were made of type IV dental stone in which different disinfectants had been incorporated (sodium hypochlorite 1%, chlorhexidine 2%) in two concentrations (50%, 100%), thus obtaining four test groups. Mentioned parameters are measured using a micro comparison device and an universal testing machine, analyzing statistically the results in comparison with the control group, prepared by standard indications. Results: Disinfectants cause a decrease of the setting expansion value (ΔL) compared to the standard group in all type of mixing percentage. Variations of compressive and flexural strength are statistically significant, particularly when adding 100% of hypochlorite 1%. Conclusions: Within the limits of this study, replacing the distilled water with disinfectants, alter the value of setting expansion and cause the model dental stone to be brittle in compression and bending.

Effect of Chemical Disinfection on Surface Detail Reproduction and Dimensional Stability of a New Vinyl Polyether Silicone Elastomeric Impression Material.

Background:Surface detail reproduction (SDR) and dimensional stability of elastomeric impression material play a crucial role in fixed prosthodontics.Aim and Objectives:The aim of this study was to compare the effect of chemical disinfection on SDR and dimensional stability of polyvinyl siloxane (PVS) and polyether (PE) with a new vinyl polyether silicone (VPES) elastomeric impression material.Materials and Methods:A stainless steel mold was made to fabricate the study specimens for nonaqueous PVS, PE, and VPES elastic dental impression materials. Single mix impression techniques with light- and heavy-body consistency of all three materials were used to prepare the test specimens. The specimens were immersed in glutaraldehyde (Cidex) 2.45% and sodium hypochlorite (Hypo) 3.0% disinfection for 15 min (T1) and 12 h (T2) immersion after which dimensional stability and SDR were recorded using stereomicroscope and digital Vernier caliper.Statistical Analysis:The data were analyzed using the one-way ANOVA, paired t-test, Kruskal–Wallis test, and Wilcoxon signed-rank test.Results:Dimensional stability at the T2 time interval showed a highly significant difference for control and glutaraldehyde groups (P < 0.001), whereas a statistically significant difference for Hypo group (P < 0.05). SDR of the three materials when compared at T1 time interval showed a statistically significant difference (P = 0.015). A comparison between two disinfectants at T1 time interval revealed a highly significant difference (P < 0.001), while at T2 interval significant difference was obtained (P = 0.009).Conclusion:VPES impressions display acceptable dimensional stability and SDR for clinical use with immersion disinfection. Although some statistically significant differences in linear dimensional stability and semidefinite programming were observed among VPES, PE, and PVS, but the clinical impact of these differences is minor considering the overall accuracy of casts which was high.

Linear dimensional stability of irreversible hydrocolloids with and without disinfection at different storage times

Irreversible hydrocolloids have been used in dental practice for decades and their pouring time has been suggested to be as short as possible; however the latest generation of alginates exhibit better properties, which could influence the fidelity of the casts. Objective: To evaluate the linear dimensional stability of stone casts obtained using two irreversible hydrocolloid brands (Cavex ColorChange and Jeltrate) after disinfection. Material and methods: Samples were divided into 16 groups (n = 10) according to brand, storage time and disinfection. Impressions were taken of a metallic master model made of stainless steel with two abutments. Cast models were obtained using type IV gypsum, after disinfection with sodium hypochlorite at 1% or without any disinfection followed by storage for four different times (immediate pouring, and after 24, 72 or 120 hours storage after obtaining the impressions) and the models were measured with a digital caliper. Data were submitted to ANOVA 3-way followed by Tukey’s test (α &lt; 0.05). Results: A statistically significant difference was detected with Jeltrate Plus after 72 and 120 hours in storage (with and without disinfection), as well as Cavex without disinfection. Differences were found for Cavex with disinfection/24 hours storage, when compared to immediate pouring (P &lt; 0.05). The alginates presented similar behavior regarding disinfection for the same time (P &gt; 0.05). Conclusion: Storage longer than 24 hours affects the fidelity of casts. Disinfection does not promote significant alteration at any of the experimental times with either material.

Linear dimensional stability of irreversible hydrocolloids with and without disinfection at different storage times

Irreversible hydrocolloids have been used in dental practice for decades and their pouring time has been suggested to be as short as possible; however the latest generation of alginates exhibit better properties, which could influence the fidelity of the casts. Objective: To evaluate the linear dimensional stability of stone casts obtained using two irreversible hydrocolloid brands (Cavex ColorChange and Jeltrate) after disinfection. Material and methods: Samples were divided into 16 groups (n = 10) according to brand, storage time and disinfection. Impressions were taken of a metallic master model made of stainless steel with two abutments. Cast models were obtained using type IV gypsum, after disinfection with sodium hypochlorite at 1% or without any disinfection followed by storage for four different times (immediate pouring, and after 24, 72 or 120 hours storage after obtaining the impressions) and the models were measured with a digital caliper. Data were submitted to ANOVA 3-way followed by Tukey’s test (α &lt; 0.05). Results: A statistically significant difference was detected with Jeltrate Plus after 72 and 120 hours in storage (with and without disinfection), as well as Cavex without disinfection. Differences were found for Cavex with disinfection/24 hours storage, when compared to immediate pouring (P &lt; 0.05). The alginates presented similar behavior regarding disinfection for the same time (P &gt; 0.05). Conclusion: Storage longer than 24 hours affects the fidelity of casts. Disinfection does not promote significant alteration at any of the experimental times with either material.

Thermal and structural micro analysis of micro silica blended fly ash based geopolymer composites

The effect of micro silica addition at 0, 5 and 10% on fly ash geopolymer composites; paste, mortar and concrete prepared using the hybrid solution of sodium silicate and sodium hydroxide cured at 80 °C for 24 h, aged for 7 days studied under elevated temperature. The incorporation of micro silica at 5% level increase the composite strength at room temperature, and it is pronounced in the paste at 800 °C (50% Strength gain). Thermal stability of the composites was studied using TGA/DTA analysis till 1000 °C. The linear dimensional stability of paste and mortar maintained till 800 °C without any physical damage. 10% of micro silica addition exerts more filling effect that damage the integrity of the bulk specimen of mortar and concrete thereby decrease the compressive strength. The XRD pattern of paste 0% (M1) and 5% micro silica (M2) confirms the presence of secondary hydration product of semi-crystalline Hydroxysodalite Na4Al3Si3O12OH at room temperature. The higher intensity of Nepheline (NaAlSiO4) and Albite (NaAlSi3O8,) phases in the M2 at 800 °C represents the Si and Al-rich N-A-S-H corroborated with the observed chemical shift of Q4(4Al) in 29Si MAS-NMR and the resonance peak shift towards 60 ppm Al(IV) from 0 ppm (Al(VI)) in 27Al MAS-NMR. The symmetric and asymmetric stretch of TOSi (TSi/Al) band in ATR FT-IR spectrum of M1 and M2 compared to verify the geopolymer network.

The use of Silica nanoparticles and microwave irradiation with Polymethyl Methcrylate denture base resin: Experimental investigation into the flexural strength and linear dimensional stability after repair and accelerated aging

The use of Silica nanoparticles and microwave irradiation with Polymethyl Methcrylate denture base resin: Experimental investigation into the flexural strength and linear dimensional stability after repair and accelerated aging

Comparison of disinfectants by immersion and spray atomization techniques on the linear dimensional stability of different interocclusal recording materials: An in vitro study.

Objective:To evaluate and compare the effect of 0.5% chlorhexidine gluconate, 1% sodium hypochlorite, and 2% glutaraldehyde by immersion and spray atomization technique on the linear dimensional stability of Jet bite, Aluwax and Ramitec interocclusal recording materials.Materials and Methods:Three representative materials: Jet bite (addition silicone), Aluwax and Ramitec (polyether) were mixed according to manufacturer's instructions and then specimens were prepared according to the specifications of ISO 4823. All the specimens except the control (distilled water) were treated with disinfectant solutions (0.5% chlorhexidine gluconate, 1% sodium hypochlorite, and 2% glutaraldehyde) for 30 and 60 min (n = 10) by spray and immersion technique. Once removed from the solutions, the test samples were washed in water for 15 s, dried and measured after 24 h 3 times using a measuring microscope with an accuracy of 0.0001 mm. Two-way ANOVA and Tukey's test with significance level of 5% were used to assess the statistical data (α = 0.05).Result:All groups showed no significant difference statistically, in linear dimension when disinfected for 30 min by spray or immersion technique. Polyether had significantly higher dimensional variation when immersed in sodium hypochlorite for 60 min. Addition silicone showed the least dimensional change which ranged from 0.024% to 0.05%, followed by polyether from 0.004% to 0.171% and Aluwax from 0.146% to 0.228%.Conclusion:To preserve the dimensions and surface of the recording materials and effective microbial elimination, restrictions should be applied in the method of disinfection and time duration. However, using the disinfectants either by spray or immersion technique, the dimensional change was <0.5% which was not clinically significant according to the American Dental Association specification no. 19 criteria within the first 24 h.

The effect of temperature on linear dimensional stability of elastomers

Objectives: The objective of this study was to investigate the effect of temperature on dimensional stability of elastomeric impression materials. Materials and Methods: Polyether and polyvinyl siloxane impressions of an International Organization for Standardization-specified test-block were photographed at two temperatures and 3 time intervals. This resulted in 12 groups (n = 10). Images were digitally calibrated and measured. Mean percentage dimensional change (%DC) was analyzed using the Variance Estimation and Precision module of Statistica 10 (Statsoft®, Southern Africa) (95% confidence), with Fisher least significant difference correction for multiple pairwise comparisons. Results: For silicone, dimensional accuracy was highest when stored at 21°C for 14 days (%DC = 0.006). This was significantly better than all other silicone groups (P < 0.05). Dimensional accuracy was worst when stored at 21°C for 8 h (%DC = 0.237) and after cooling-off from 66°C (%DC = 0.300), with no difference between latter groups (P = 0.187). For polyether, dimensional accuracy was highest when stored at 21°C for 14 days (%DC = −0.272). This was significantly better than all other polyether groups (P < 0.05). Dimensional accuracy was worst when stored at 21°C for 8 h (%DC = 0.364) and after cooling-off from 66°C (%DC = 0.306), with no difference between latter groups (P = 0.199). Comparing polyether with silicone, %DC did not differ between the two materials when kept at 21°C for 14 days and when cooled-off after heat exposure for 8 h. At all other instances, the %DC between the two materials differed, with silicone always closest to zero %DC. Conclusions: Exposing silicone and polyether to high temperature doesn't lead to higher dimensional inaccuracy on the short-term compared to keeping them at 21°C. However, heat has an effect on shelf-life (14 days) of impressions, decreasing accuracy. This effect is worse for polyether.

A comparative evaluation of dimensional stability of three types of interocclusal recording materials-an in-vitro multi-centre study

BackgroundThe introduction of different interocclusal recording materials has put clinicians in dilemma that which material should be used in routine clinical practice for precise recording and transferring of accurate existing occlusal records for articulation of patient’s diagnostic or working casts in the fabrication of good satisfactory prosthesis. In the era of developing world of dentistry the different materials are introduced for interocclusal record with different brand names because of this; the utility of the material is confusing for successful delivery of prosthesis with lack of in vitro or in vivo studies which will predict the property of the material with utility recommendations.Purpose of the studyThe aim of this multicenter research is to evaluate the time dependent linear dimensional stability of three types of interocclusal recording materials; which gives very clear idea to clinicians in regard to its usage in routine practice and recommendations for usage of the different materials. Also to find out ideal time for articulation of three types of interocclusal recording materials with accuracy.Materials and methodCommercially available and ADA approved Polyether bite registration paste (Ramitec), Poly vinyl siloxane bite registration paste (Jetbite) and Zinc oxide eugenol (ZOE) bite registration paste (Super bite) were used in the study.A stainless steel die was made according to modified American dental Associations (ADA) specification no. 19. Each one of the tested materials were manipulated according to manufacturers’ instructions. The materials separated from die, 3-mins after their respective setting time, resulted in disks of standard diameter. Two parallel lines and three perpendicular lines reproduced on the surface. The distance between two parallel lines was measured at different time intervals i.e. 1 hour, 24, 48 and 72 hours by using travelling microscope (magnus) and compared with standard die measurements made according to ADA specification no.19 to find out the dimensional stability of these interocclusal recording materials. Total 120 samples were made for observation and results were subjected to statistical analysis. Statistical analysis was performed using analysis of variance (ANOVA) and then Tukey’s Honestly Significant Difference (HSD) test for comparison among groups at the 0.05 level of significance. After statistical analysis of the data, results were obtained and analyzed for interpretation.ResultsThe results shows significant difference between the dimensional stability of all three material at different intervals with p-value <0.05. Comparatively the polyether bite registration material showed less distortion with good dimensional stability compared to Poly vinyl siloxane bite (Jetbite), Zinc oxide eugenol(ZOE) bite (Super bite) at 1 hour, 24, 48, and 72 hours.ConclusionThe dimensional stability decreased with increase in time and is influenced by both material factor and time factor. Polyether was found to be more dimensionally stable interocclusal recording material, which was followed by Silicone and Zinc oxide eugenol (ZOE). The dimensional stability of Polyether was good. Zinc oxide eugenol is dimensionally more unstable when compared with polyether and polyvinyl siloxane. We recommend that the polyether interocclusal records must be articulated within 48 hours and Polyvinylsiloxane interocclusal records must be articulated within 24 hours and the ZOE should be articulated within 1 hour to get a correct restoration to have very minimum distortion and maximum satisfaction without failure of prosthesis.

Effect of Incorporation of Disinfectant Solutions on Setting Time, Linear Dimensional Stability, and Detail Reproduction in Dental Stone Casts

The aim of this paper was to analyze the influence of incorporation of disinfectants during the cast die stone-setting time. Setting time, linear dimensional stability, and reproduction details on casts were measured. Die stone type IV specimens with disinfection solutions (sodium hypochlorite 1%, glutaraldehyde 2%, chlorhexidine 2%) were incorporated in two concentrations (50%, 100%). The detail reproduction, dimensional stability, and setting time were tested in accordance with ADA recommendations. Disinfecting solutions promoted an increase in setting time compared to control; sodium hypochlorite was responsible for the highest setting time. The addition of undiluted sodium hypochlorite 1.0% led to contraction during setting, but the groups with 50% diluted sodium hypochlorite 1.0% and undiluted chlorhexidine 2.0% resulted in intermediate values compared to the other groups, thus matching the control. The others did not demonstrate any effect on expansion. For detail reproduction, it was observed that the control group presented results similar to the others, except those where sodium hypochlorite was added. The addition of sodium hypochlorite in both dilutions significantly altered, negatively, all the evaluated properties. But the addition of glutaraldehyde and chlorhexidine did not promote any significant alterations in the evaluated properties.

Effect of the disinfection technique on the linear dimensional stability of dental impression materials

The purpose of this study was to evaluate the dimensional stability of heavy and light bodied condensation silicones after immersion in disinfectant solution for 10 or 20 minutes. The impression materials were Optosil Comfort and Xantopren VL Plus and the disinfectant solutions were 1% sodium hypochlorite and 2% glutaraldehyde. Impressions were made on a perforated stainless steel tray, according to the American Dental Association specification No. 19, adding up to a total of 50 samples. The double mixing method (one time, two viscosities) was used. Impressions were removed from the roulette block after 7 minutes to ensure complete curing and then immersed in the solutions. Impressions not submitted to treatment composed the control group. After these steps, the impressions were removed from the solution, rinsed in running water and air-dried. Three-dimensional measurements were calculated using an optic microscope graduated at 0.001 mm. The two-way ANOVA indicated no differences (p>0.05) for any combination between variables. The results showed that the solution studied can be safely used to disinfect condensation silicone in clinical prosthodontic procedures.