Hydrophilic Vinyl Polysiloxane Impression Materials Research Articles

Improved water absorption behaviour of experimental hydrophilic vinyl polysiloxane (VPS) impression materials incorporating a crosslinking agent and a novel surfactant

ObjectivesTo study the effects of incorporating a further crosslinking agent and a novel surfactant on the water absorption behaviour of experimental VPS impression materials. MethodsPart 1: The water uptake behaviour of Aquasil-Ultra-Monophase (AqM) was studied gravimetrically in three media (DW, 1%NaOCl and Perform ID), at 23 °C and 37 °C, over a period of one and four-months (n = 5) to gain information on long-term immersion. Part 2: Five experimental materials were formulated: Exp-I and II as hydrophobic and Exp-III-V as hydrophilic, containing an additional cross-linking agent (TFDMSOS) and Rhodasurf CET-2 surfactant. Their water uptake and desorption (both at 23 °C) properties (gravemetrically), solubility, pH and diffusion coefficient (DC) data were compared with three commercial, hydrophilic VPS impression materials, over seven days (n = 5). The results were analysed statistically. ResultsPart 1: Significant differences in water absorbed by AqM were observed in the three media at 23 °C. Aq M had a significantly higher uptake in 2% Perform ID, than in DW and NaOCl. At 37 °C, over four-months the uptake profiles were more enhanced and differed. Part 2: All Exp and commercial materials significantly increased in weight in both media (DW and 1% NaOCl at 23 °C), with differing uptake profiles and non-reached equilibrium. Exp-VPS absorbed significantly less water than commercial-VPS. Desorption of all VPS from both parts was faster than absorption, followed Fickian diffusion kinetics and reached equilibrium within 1–3 days. Desorption DCs for Exp-VPS were higher than commercial materials (10−10 versus 10−11 m2 s−1). The solubility was higher in 1% NaOCl compared to DW. The pH of DW after immersion of samples significantly increased compared to 1% NaOCl. SignificanceThe incorporation of novel cross-linking agent, TFDMSOS and non-ionic surfactant, Rhodasurf CET-2, (ethoxylated-cetyl-oleyl alcohol) improved the dimensional stability of hydrophilic Exp-VPS in DW and 1% NaOCl. These materials merit further research in producing accurate casts of the patient’s anatomy following disinfection.

Photogrammetric Analysis of Multiple Implant Abutment Impressions under Different Conditions

Purpose: The aim of this investigation was to evaluate and compare the dimensional accuracy of hydrophilic polysiloxane, vinyl polysiloxane (VPS), and polyether (PE) impression materials under dry, moist and wet conditions. Methods: An acrylic master model including 6 implants was formed, and 108 impressions were made up of this acrylic model at total. In this study, the materials of hydrophilic polysiloxane impression material, 1 hydrophilic vinyl polysiloxane impression material and 1 polyether impression material were tested. Twelve impression of each material were created under dry, moist and wet respectively. Two reference distances were evaluated on each study model by using a graphics-editing program whereas for comparison of mean dimensional changes one-way analysis of variance and Student t-test were used. Results: One-way analysis of variance revealed significant differences between impression materials and conditions (P P Conclusions: All impression materials showed a statistically significant difference under dry, moist and wet conditions.

Dimensional Accuracy of Hydrophilic and Hydrophobic VPS Impression Materials Using Different Impression Techniques - An Invitro Study.

The dimensional stability of the impression material could have an influence on the accuracy of the final restoration. Vinyl Polysiloxane Impression materials (VPS) are most frequently used as the impression material in fixed prosthodontics. As VPS is hydrophobic when it is poured with gypsum products, manufacturers added intrinsic surfactants and marketed as hydrophilic VPS. These hydrophilic VPS have shown increased wettability with gypsum slurries. VPS are available in different viscosities ranging from very low to very high for usage under different impression techniques. To compare the dimensional accuracy of hydrophilic VPS and hydrophobic VPS using monophase, one step and two step putty wash impression techniques. To test the dimensional accuracy of the impression materials a stainless steel die was fabricated as prescribed by ADA specification no. 19 for elastomeric impression materials. A total of 60 impressions were made. The materials were divided into two groups, Group1 hydrophilic VPS (Aquasil) and Group 2 hydrophobic VPS (Variotime). These were further divided into three subgroups A, B, C for monophase, one-step and two-step putty wash technique with 10 samples in each subgroup. The dimensional accuracy of the impressions was evaluated after 24 hours using vertical profile projector with lens magnification range of 20X-125X illumination. The study was analyzed through one-way ANOVA, post-hoc Tukey HSD test and unpaired t-test for mean comparison between groups. Results showed that the three different impression techniques (monophase, 1-step, 2-step putty wash techniques) did cause significant change in dimensional accuracy between hydrophilic VPS and hydrophobic VPS impression materials. One-way ANOVA disclosed, mean dimensional change and SD for hydrophilic VPS varied between 0.56% and 0.16%, which were low, suggesting hydrophilic VPS was satisfactory with all three impression techniques. However, mean dimensional change and SD for hydrophobic VPS were much higher with monophase, mere increase for 1-step and 2-step, than the standard steel die (p<0.05). Unpaired t-test displayed that hydrophilic VPS judged satisfactory compared to hydrophobic VPS among 1-step and 2-step impression technique. Within the limitations of this study, it can be concluded that hydrophilic Vinyl polysiloxane was more dimensionally accurate than hydrophobic Vinyl polysiloxane using monophase, one step and two step putty wash impression techniques under moist conditions.

Investigation of dental materials as skin simulants for forensic skin/skull/brain model impact testing.

The purpose of this study was to measure the tear strength and hardness of four different dental silicones in comparison to that of porcine skin. Specimens were prepared (n = 20/group) according to ASTM D624-00, using three hydrophilic vinyl polysiloxane impression materials, one duplication silicone, and fresh porcine skin. A universal testing machine was used to strain each test specimen until complete rupture and calculate its tear strength (kNm(-1)). Failure analysis was then conducted using a stereoscopic zoom light microscope, as well as a scanning electron microscope (SEM). A shore A-type durometer was used to measure the hardness of all specimens. The tear strength for the silicones ranged from 1.75 to 9.58 kNm(-1) and the pigskin from 3.65 to 56.40 kNm(-1). The mean shore hardness for the silicones ranged from 16.275 to 62.65DU and the pigskin had a mean shore hardness of 22.65DU, with p values <0.0125 (0.05/4). Failure analysis of the silicone materials showed the origin of failure being in the tension side of the specimens and typical failure patterns were observed. Examining the materials under a SEM revealed that materials with higher viscosity presented with a larger amount of filler particle content than silicones with low viscosity, with the duplication silicone having no filler content. Dental silicones are a good alternative for skin in studies that require a skin simulant.

A Comparative Evaluation of Dimensional Accuracy and Surface Detail Reproduction of Four Hydrophilic Vinyl Polysiloxane Impression Materials Tested Under Dry, Moist, and Wet Conditions-An In Vitro Study.

Vinyl polysiloxane (VPS) impression materials have application in a wide variety of situations in both fixed and removable prosthodontics. A major limitation of VPS impression materials is their hydrophobicity. There are two aspects of this problem, the wettability of the polymerized impression by dental gypsum materials and the ability of the unpolymerized material to wet intraoral tissues. To address this problem, manufacturers have added surfactants and labelled these new products as "hydrophilic vinyl polysiloxane." The purpose of this study was to evaluate and compare dimensional accuracy and surface detail reproduction of four hydrophilic VPS impression materials, when used under dry, moist, and wet conditions. A total of 180 samples were made of stainless steel die similar to as described in ADA sp. no. 19. The die was scored with three horizontal and two vertical lines. Impressions were made under dry, moist and wet conditions. Dimensional accuracy was measured by comparing the length of the middle horizontal line in each impression to the same line on the metal die, by using Universal Length Measuring machine. A 2-way ANOVA was performed on the percentage change data for measured lengths of the 4 impression materials under the 3 conditions to evaluate dimensional accuracy. Surface detail was evaluated in two ways: (1) by use of criteria similar to ADA sp. no. 19 for detail reproduction, and (2) by use of a method that categorized the impressions as satisfactory or unsatisfactory based on their surface characteristics: presence of pits, voids, or roughness. Pearson X2 (α=0.05) was used to compare surface detail reproduction results. Conditions (dry, moist, and wet) did not cause significant adverse effects on the dimensional accuracy of all the four material. With both surface detail analyses, dry, moist, and wet conditions had a significant effect on the detail reproduction of all the four materials (P<0.05). The study concluded that the dimensional accuracy of all the four impression materials tested was well within ADA standards. Best surface detail results were obtained only under dry conditions for all the four materials.

Material Conformity and Bactericidal Characteristics of High-Density Ozone Disinfection in Vinyl Polysiloxane Impression and PMMA Dentistry Fillings

Disinfection was investigated in high-density ozone produced by dielectric barrier discharge under atmospheric pressure. Disinfection was studied on three-dimensional carriers made of hydrophilic vinyl-polysiloxane impression material and granular acrylic resin used for oral surgery. Experimental results indicate disinfection of spore-forming bacteria: Geobacillus stearothermophilus and Bacillus atrophaeus, and selected species of opportunistic pathogens: Aspergillus niger, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Candida albicans.

Evaluation of the accuracy, precision and validity of hydrophilic vinyl polysiloxane impression material for bite mark analysis.

The present study was undertaken to assess the accuracy, precision and validity of hydrophilic Vinyl Poly Siloxane [VPS] impression material for bite mark documentation and analysis. Medium body VPS impressions of maxillary and mandibular anterior teeth among thirty subjects were taken and dental stone casts prepared. Hollow volume overlays were made and metric analysis was done using advanced imaging software like Adobe Photoshop - 9 and Image J. These values were compared to the measurements taken from bite mark impressions of the same 30 individuals on wax wafers using light body VPS material. The mean differences in the parameters measured by the different techniques were compared using Intra Class Correlation Coefficients [ICCC]. Additionally validity parameters such as sensitivity, specificity, positive and negative predictive value were computed.

Dimensional accuracy and detail reproduction of two hydrophilic vinyl polysiloxane impression materials tested under different conditions

A limitation of vinyl polysiloxane (VPS) impression materials is hydrophobicity, and manufacturers have added surfactants and labeled these new products as "hydrophilic." The purpose of this investigation was to evaluate and compare the dimensional accuracy and surface detail reproduction of two hydrophilic VPS impression materials under dry, moist, and wet conditions. Ten impressions were made under dry, moist, and wet conditions respectively, with monophase, and regular body VPS impression material using a stainless steel metal die similar to that described in American Dental Association (ADA) specification 19, with lines scribed on it. Dimensional accuracy was measured by comparing the average length of the middle horizontal line in each impression to the same line on the metal die, by using a measuring microscope. The surface detail was evaluated. A one-way analysis of variance and Student t-test were used to compare mean dimensional changes (α = 0.05). Conditions (dry, moist, and wet) did not cause significant adverse effects on the dimensional accuracy of either material. The mean dimensional changes were 0.00084% (+0.00041%) for monophase and 0.00119% (+0.00033%) for regular body. Monophase material was satisfactory in detail reproduction 100% of the time in dry conditions, 90% in moist, and only 20% in wet conditions. The regular body showed 100% satisfactory impressions in dry, 80% in moist, and 10% in wet conditions. With the additional smooth surface evaluation, only under dry conditions impressions with clinically acceptable surface quality were produced. Dimensional changes for both materials were well within ADA standards of minimal shrinkage value of 0.5%.

ガイドプレーンの設定条件がエーカースクラスプ装着時の支台歯変位に及ぼす影響

Three types of guide plane were compared to clarify the effect of guide plane setting conditions on abutment displacement which arises when an Akers clasp is inserted. An experimental model with an artificial periodontal membrane made of hydrophilic vinyl polysiloxane impression material was created. Abutments given a guide plane with only a clasp body (G1), a guide plane whose span extended as far as the reciprocal clasp arm shoulder region diametrically opposite the retention area (G2), and a guide plane for the entire reciprocal clasp arm region (G3) were created, and an Akers clasp was made for each abutment. The amount of abutment displacement and the degree of rotation that arose in the abutment when the Akers clasp was inserted were detected with three laser displacement sensors for comparison. The amount of abutment displacement that arose when the clasp was inserted was higher with G1 than with G2 and G3 in the lingual and distal directions, and no difference was seen between G2 and G3. It was lower with G1 than with G2 and G3 in the buccal direction, and no difference was seen between G2 and G3. It was high with G1 in the mesial direction, and the abutment rotation was high, whereas they were low in the case of G3. A difference was seen between each condition. Differences in guide plane setting conditions affected the abutment displacement that arose when an Akers clasp was inserted, suggesting that a difference in reciprocal action is seen depending on the setting conditions of the guide plane.

High-Grade Disinfection Using High-Density Ozone Chemical and Structural Properties of Jordanian Diatomaceous Clay Supported Metal Oxides Chemical and Structural Properties of Jordanian Diatomaceous Clay Supported Metal Oxides Chemical and Structural Properties of Jordanian Diatomaceous Clay Supported Metal Oxides Chemical and Structural Properties of Jordanian Diatomaceous Clay Supported Metal Oxides

AbstractHigh-grade disinfection was investigated in high-density ozone excited by a dielectric barrier discharge. The experimental result indicated complete disinfections of Bacillus atrophaeus, a spore forming bacterium and Aspergillus niger, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Candida albicans have been achieved for the surface exposed high density ozone on metallic career with smooth surface or Exafine, a type of hydrophilic vinyl polysiloxane impression material with complex surface.

Dimensional accuracy and surface detail reproduction of two hydrophilic vinyl polysiloxane impression materials tested under dry, moist, and wet conditions

Statement of problem A major limitation of vinyl polysiloxane (VPS) impression materials is their hydrophobicity. There are 2 aspects to this problem, the wettability of the polymerized impression by dental gypsum materials and the ability of the unpolymerized material to wet intraoral tissues. To address this problem, manufacturers have added surfactants and labeled the new products as hydrophilic vinyl polysiloxane. Purpose The purpose of this investigation was to compare dimensional accuracy and surface detail reproduction of 2 hydrophilic VPS impression materials, when used under dry, moist, and wet conditions. Material and methods A total of 102 impressions were made of stainless steel metal dies similar to those described in American Dental Association (ADA) specification 19. The dies had 2 vertical and 3 horizontal lines inscribed on their superior surfaces. Impressions were made under dry, moist, and wet conditions. Dimensional accuracy was measured by comparing the average length of the middle horizontal line in each impression to the same line on the metal die, by use of a measuring microscope with an accuracy of 0.001 mm. A 2-way analysis of variance and least significant difference post hoc test were used to compare mean dimensional changes (α=.05). Surface detail reproduction was evaluated in 2 ways: (1) by use of criteria similar to ADA specification 19 for detail reproduction, continuous replication of at least 2 of the 3 horizontal lines, and (2) by use of a method developed for this study that categorized the impressions as satisfactory or unsatisfactory based on their surface characteristics: presence of pits, voids, or roughness. Pearson χ 2 (α=.05) was used to compare detail reproduction results. Results Conditions (dry, moist, and wet) did not cause significant adverse effects on the dimensional accuracy of either material. The mean dimensional change and SD were 0.005% ± 0.002% or less. With both surface detail analyses, dry, moist, and wet conditions had a significant effect on the detail reproduction of both materials ( P<.05). Only under dry conditions did both impression materials continuously replicate at least 2 of the 3 horizontal lines 100% of the time. Under moist conditions, 82% of the Aquasil impressions and 100% of the Reprosil impressions were judged satisfactory, while under wet conditions, only 47% Aquasil and 11% Reprosil impressions were satisfactory. With the additional surface detail characterization, only under dry conditions were impressions produced with clinically acceptable surface quality (Aquasil 77% and Reprosil 100% satisfactory). Conclusions Dimensional accuracy of both materials tested was well within ADA standards. Best surface detail results were obtained only under dry conditions for both materials.

Patello-femoral contact area and compressive force after anteromedial displacement of tibial tuberosity in amputated knees

Contact force and contact area in the patello-femoral joint was biomechanically analyzed using seven amputated legs. The knees were fixed firmly to the experimental apparatus and 300 N of tension was applied to the quadriceps tendon. Total contact force was measured using pressure-sensitive film, and the ratio of the contact area to the patellar joint surface (%) was measured using hydrophilic vinyl polysiloxane impression material. At a Q-angle of 0° with no advancement, 10 mm and 20 mm advancement of the tibial tuberosity, the total contact force on the patello-femoral joint at a knee flexion of 45° was 266±55 N, 191±58 N and 146±58 N, respectively. The total contact force became smaller as the advancement of the tibial tuberosity changed to 5, 10, 15 and 20 mm. Especially, the total contact force with Q-angle of 0° and anterior advancement of 15 and 20 mm was significantly smaller than that with no advancement. With a Q-angle of 0°, the contact area of the patello-femoral joint at 10 mm advancement was the greatest, occupying 30.1±9.9% of the whole patellar joint surface. The mean contact pressure with Q-angle of 0° and anterior advancement of 10 mm was smaller than that with all other positions, but there was no significant difference. In this experiment, combined anterior and medial displacement of the tibial tuberosity reduced the contact force in the patello-femoral joint of the amputated legs, and an advancement of 10 mm achieved optimal reduction of force and the greatest contact area.