Polyvinyl Siloxane Impression Material Research Articles

Fracture resistance of endodontically treated root obturated with different root canal sealers( A comparative in vitro study)

Aim: The aim of this study is to evaluate and compare the fracture resistance of endodontically treated root obturated with four different root canal sealers.. Methods: Sixty extracted palatal root of upper molars were collected and sectioned to get a 11mm root length. All root canals were instrumented using edge endo X7 system rotary files and 35# size was the final size used to finish all the canals. After instrumentation the samples were divided into four groups of 15 samples in each according to the type of sealer used, a single cone obturation technique was used: Group 1: obturated with AH Plus sealer and gutta-percha. Group 2: obturated with Neosealer BC sealer and gutta-percha. Group 3: Obturated with MTA-Fillapex sealer and gutta-percha. Group 4: Obturated with OneFill BC sealer and gutta-percha. After incubation period of 7 days at 37°C and 100% humidity the samples covered with thin layer polyvinylsiloxane impression material to simulate a periodontal membrane and then molded in acrylic blocks so as to set the samples ready for fracture resistance test using universal testing machine at a cross head speed of 0.5mm/min., One-way ANOVA and Posthoc tests assessed the data statistically. Results: The results showed that fracture resistance was significantly higher in those canals that were filled with Neosealer BC sealer (69.90N) in comparison to the other different sealers used in the study (p≤0.05). Conclusion: Under the condition of this study, the following conclusions can be derived: The application of any root canal sealers resulted in an enhancement of the resistance to fractures in teeth that have undergone endodontic treatment. Neosealer Bioceramic sealer group showed the highest fracture resistance than other groups. Followed by Onefill bioceramic, MTA Fillapex and Ah plus.

In vitro evaluation of the impact of intraoral scanner, scanning aids, and the scanned arch on the scan accuracy of edentulous arches.

To assess the accuracy of complete maxillary and mandibular edentulous arch scans obtained using two different intraoral scanners (IOSs), with and without scanning aids, and to compare these results to those obtained using conventional impression methods. Two IOSs were used (TRIOS 4 [TRI] and Emerald S [EMR]) to scan maxillary and mandibular typodonts. The typodonts were scanned without scanning aids [TRI_WSA and EMR_WSA groups] (n = 10). The typodonts were then scanned under four scanning aid conditions (n = 10): composite markers [TRI_MRK and EMR_MRK groups], scanning spray [TRI_SPR and EMR_SPR groups], pressure indicating paste [TRI_PIP and EMR_PIP groups], and liquid-type scanning aid [TRI_LQD and EMR_LQD groups]. Conventional impressions of both arches were also made using irreversible hydrocolloids in stock trays [IHC] and using polyvinyl siloxane (PVS) impression material in custom trays (n = 10) which were digitized using a laboratory scanner. Using a metrology software program, all scans were compared to a reference scan in order to assess trueness and to each other to assess precision. Trueness and precision were expressed as the root mean square (RMS) of the absolute deviation values and the statistical analysis was modeled on a logarithmic scale using fixed-effects models to meet model assumptions (α = 0.05). The main effect of arch (p = 0.004), scanner (p < 0.001), scanning aid (p = 0.041), and the interaction between scanner and scanning aid (p = 0.027) had a significant effect on mean RMS values of trueness. The arch (p = 0.015) and scanner (p < 0.001) had a significant effect on the mean RMS values of precision. The maxillary arch had better accuracy compared to the mandible. The TRIOS 4 scanner had better accuracy than both the Emerald S scanner and conventional impressions. The Emerald S had better precision than conventional impressions. The scanning spray and liquid-type scanning aids produced the best trueness with the TRIOS 4 scanner, while the liquid-type scanning aid and composite markers produced the best trueness for the Emerald S scanner. The scanned arch and the type of scanner had a significant effect on the accuracy of digital scans of completely edentulous arches. The scanning aid had a significant effect on the trueness of digital scans of completely edentulous arches which varied depending on the scanner used.

Digital Evaluation of Trueness and Precision of Modern Impression Materials in Implant- Retained Mandibular Overdentures.

The purpose of this in vitro study was to evaluate the dimensional accuracy, trueness, and precision of vinyl siloxane ether (VSXE) and polyvinylsiloxane (PVS) impression materials using different impression techniques. A three-dimensional (3D) printed mandibular model with implants and metal rods served as the reference model. Impressions were taken in custom trays, resulting in four groups: PVS-closed-tray, VSXE-closed-tray, PVS-open-tray, and VSXE-open-tray. The reference model and impressions were scanned and analyzed using 3D analysis software to assess the trueness and precision within each group. There was significant difference in trueness between the groups, with PVS closed tray showing a higher deviation than VSXE-closed-tray and PVS-open-tray. VSXE-open-tray had the lowest deviation, which was statistically significant. In terms of precision, PVS-closed-tray showed the highest deviation, while no significant differences were found among the other groups. VSXE impression material with an open tray technique consistently demonstrated the highest levels of accuracy and precision. Conversely, PVS impression material with a closed tray technique yielded less favorable results. Better understanding of trueness and precision of new impression materials with new impression techniques will increase their clinical effectiveness.

Food impaction on three-dimensional printed models with periodontal ligament simulation.

This study aims to evaluate food impaction on three-dimensional (3D) printed models with periodontal ligament simulation. Based on a commercial typodont pair, 3D maxillary and mandibular models were created with no teeth and with tooth sockets that were 1 mm wider than the original ones from 24 to 27 or 34 to 37 for periodontal ligament simulation with vinyl polysiloxane impression material. In total, 35 pairs of 7 combinations, including maxillary/mandibular typodonts in occlusion with maxillary/mandibular 3D models with/without a distal gap of canines on 3D models (tooth 23 or 33) were mounted on hinge articulators and divided into seven groups (n = 5). Each sample experienced the same manual chewing simulation on a customized device. The proximal surfaces were photographed to measure the percentage of food impaction area using ImageJ software. Group with fixed maxillary and mandibular teeth showed more food impaction than other groups with significant differences in the average of maxilla and the average of all proximal areas. The flexibility of the periodontal ligament and the degree of freedom of the teeth in their sockets may contribute to the extent of food impaction in proximal spaces.

A Clinical Comparison of Dental impression accuracy between One-step and Two-step Dual phase impression technique by using Polyvinyl Siloxane Impression Material.

Objective:: The objective was to assess the number of visible defects within impression made by two different techniques. Methodology: This was comparative cross-sectional study was conducted between June 2019 to December 2019 at out patient department of Institue of dentistry, LUMHS Jamshoro. Two impressions were made from 53 crown preparation by using one step and two step dual phase impression techniques. Totaling to 106 impressions. Polyvinyl Siloxane impression material was used with each technique. Evaluation of impressions were made for tears, voids and bubbles and impression were compute as acceptable (A or B) and unacceptable (C or D). Result: There was no significant difference seen in proportion of overall evaluation of two impression technique, as compared by using “Chi-square test”. Conclusion: Insignificant difference was seen b/w one step and two step dual phase impression techniques. Keywords: One step impression technique, two step dual phase impression technique, dimensional accuracy.

A comparative in vitro analysis of various temporization materials with respect to pulp chamber temperature changes during polymerization.

(1) To compare the temperature rise in the pulp chamber with different resin materials used for making provisional fixed partial dentures in anterior and posterior region while using Polyvinylsiloxane impression materials as matrix. (2) To identify a superior provisionalization material based on the amount of heat dissipated suitable for anterior and posterior provisional fixed partial denture fabrication. Temporary crowns and bridges are integral to Fixed Prosthodontics. It has been observed that conventional fixed prosthesis temporisation materials release heat due to the exothermic polymerisation reaction. When such a provisional material is directly let to set on a vital tooth, the heat transfer causes irreversible changes in the pulp tissue depending of the degree of change. Hence, this study observes amount of heat generation in various materials during temporisation procedure, by simulating similar conditions. Two Models were fabricated, one simulating missing lateral incisor (Model A) and another simulating missing first molar (Model B). Intact maxillary central incisors and canine for Model A and intact mandibular Second Premolar and Second Molar were selected to act as abutments. These abutment teeth were fitted with the tip of a K-type Thermocouple inside their pulp chambers and these were connected to a digital thermometer. Five temporisation materials were chosen for fabrication of temporary crowns through Direct technique. (1) polymethy methacrylate (Self Cure acrylic), (2) bisacryl composite (Protemp 4), (3) visible light cure urethane dimethacrylate (Revotec LC), (4) barium glass and fumed silica infused methacrylate (Dentsply Integrity) and (5)nano-hybrid composite (VOCO Structur 3). Ten observations were made for each provisional material on each model. During each observation, temperature rise was recorded at 30s interval from the time of application, through the peak and till a decrease in temperature is observed. Polyvinyl siloxane was used as matrix for all except light cure resin, where polypropylene sheet was used. Anova test used for statistical. ANOVA test revealed that there was a significant difference in the temperature changes associated with the provisional restorative materials used. Among the five, polymethy methacrylate (self cure resin) showed the maximum rise in temperature, followed by bisacryl composite (Protemp 4), visible light cure urethane dimethacrylate (Revotec LC), barium glass and fumed silica infused methacrylate (Dentsply Integrity) and nano-hybrid composite (VOCO Structur 3). There was no comparable difference between Model A and B but an overall reduction of temperature rise was observed in model B. VOCO Structur 3 showed the least temperature rise in the pulp chamber, and overall temperature rise was less for model B which can be attributed to the residual dentin thickness.

Effectiveness of Microwave Sterilization on Surface Roughness of Polyvinyl Siloxane Impression Material

Effectiveness of Microwave Sterilization on Surface Roughness of Polyvinyl Siloxane 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.

A Comparative Evaluation of Three Methods of Disinfection of Gypsum Casts and the Changes in Surface Roughness and Dimensional Accuracy after Disinfection-An Ex Vivo Study.

One of the major problems of everyday dental practice is cross-contamination. It can place office personnel, dentists, and patients at risk of acquiring serious illness. Disinfection helps in controlling this cross-contamination to an extent. The evaluation was done to find the efficient disinfection method on gypsum casts. The aim of this study is to evaluate and compare the efficacy of three methods of disinfection of gypsum casts, namely, chemical disinfection by immersion, spray method, and microwave method, and also to evaluate and compare changes in surface roughness and dimensional accuracy between the three methods after disinfection. Ex vivo and experimental study. Thirty participants were selected, and impressions of the maxillary arch were made using polyvinyl siloxane impression material. Ninety type IV die stone gypsum casts were poured. It was divided into three groups and was subjected to chemical disinfection by immersion and spray methods, and microwave method. The disinfected casts were evaluated for microbial growth, surface roughness, and dimensional accuracy. It was performed by using the one-way analysis of variance test and paired t-test followed by the Kruskal - Wallis test and Wilcoxon signed rank test (α = 0.05). Microwave disinfection was more effective than both immersion and spray chemical disinfection methods (P < 0.010 and <0.001). The surface roughness of the microwave-irradiated casts had significantly increased after disinfection. However, there were no significant dimensional changes by any of the methods of disinfection. Within the limitations of the study, the microwave method of disinfection is more effective in eradicating microorganisms when compared to chemical methods of disinfection by immersion and spray methods.

Influence of the Crystallization Firing Process on Marginal and Internal Adaptation of Silicate-based Glass-ceramic Inlays Fabricated With a CAD/CAM Chairside System.

Computer-aided design/computer-aided manufacturing (CAD/CAM) systems are widely used in dental treatment. Clinicians can use chairside CAD/CAM technology, which has the advantage of being able to fabricate inlays on the same day. We aimed to evaluate the effects of crystallization firing processes, fabrication methods (one-step and two-step), and materials on marginal and internal adaptations of silicate-based glass-ceramic all-ceramic inlays fabricated with CAD/CAM chairside systems. Ten artificial mandibular left first molars were prepared with standardized ceramic class II mesial-occlusal (MO) inlay cavities. Optical impressions were obtained using CEREC Omnicam Ban. IPS e-max CAD (IE), (Ivoclar Vivadent, Schaan, Liechtenstein), Initial LiSi Block (LS) (Hongo, Bunkyoku, Tokyo, Japan), VITA Suprinity (SP), (Vita Zahnfabrick, Bad Säckingen, Germany), and Celtra Duo (CD) (Ivoclar Vivadent, Schaan, Liechtenstein) (n=10) were milled using CEREC MC XL (Bensheim, Germany). IE and SP were crystallization-fired using CEREC Speed Fire. The silicone replica technique was used for the measurement of internal (axial and pulpal walls) and marginal (cervical and occlusal edge) adaptations. The adaptations were measured using a thin layer of light-body polyvinyl siloxane impression material placed between the master tooth inlay preparation and restoration. Marginal and internal adaptations of IE, LS, SP, and CD were measured using a stereomicroscope (500×). For IE and SP, marginal and internal adaptations were measured before and after the crystallization firing process. Data analyses were conducted using one-way ANOVA and the Tukey test. For IE and SP, marginal and internal adaptations before and after the crystallization firing process were analyzed using the t-test. The significance level was set at α=0.05. One-way ANOVA revealed statistically significant differences in occlusal and cervical edge marginal adaptations among the material groups (p<0.001). The Tukey HSD test revealed a significant difference in marginal occlusal and cervical edge adaptations between LS and CD groups and IE and SP groups (p≤0.05). For IE and SP inlays, the t-test revealed a significant difference between occlusal and cervical edge adaptations before the crystallization firing process and those after the crystallization firing process, with the latter group showing a more significant discrepancy in adaptation than the former group (p≤0.05). Fabrication methods (one- and two-step) affected the marginal adaptation compatibility but not internal compatibility of MO inlays. The crystallization firing process affected the marginal adaptation of inlays using lithium silicate or lithium disilicate glass-ceramics. However, adaptation to the cavity was considered clinically acceptable for all materials.

Comparison of the elastic recovery and strain-in-compression of commercial and novel vinyl polysiloxane impression materials incorporating a novel crosslinking agent and a surfactant.

This study aims to formulate experimental vinylpolysiloxane (VPS) impression materials and compare their elastic recovery and strain-in-compressions with three commercial VPS materials (Aquasil, Elite, and Extrude). Five experimental materials (Exp), two hydrophobic (Exp-I and II) and three hydrophilic (Exp-III, IV and V) were developed. Exp 1 contained vinyl-terminated poly-dimethyl siloxane and a conventional cross-linking agent (poly methylhydrosiloxane), while Exp- II contained a novel cross-linking agent that is tetra-functional dimethyl-silyl-ortho-silicate (TFDMSOS). Exp III-V (hydrophilic materials) were formulated by incorporating different concentrations of non-ionic surfactant (Rhodasurf CET-2) into Exp II formulation. Measurement of elastic recovery and strain-in-compression for commercial and experimental materials were performed according to ISO4823 standard using the calibrated mechanical testing machine (Tinius Olsen). One-way analysis of variance (one-way ANOVA) and Tukey's post-hoc (HSD) test were used for statistical analysis and a p-value of ≤ 0.05 was considered significant. Exp-I has statistically similar values to commercial VPS. The Exp-II showed the highest elastic recovery, while % elastic recovery was reduced with the addition of the non-ionic surfactant (Rhodasurf CET-2). The % reduction was directly related to the concentration of Rhodasurf CET-2. In addition, Exp II had significantly higher strain-in-compression values compared to Exp-I and commercial materials. These values were further increased with the addition of a non-ionic surfactant (Rhodasurf CET-2) was added (Exp-III, IV and V).

Comparison of the accuracy between full-arch digital scans and scannable impression materials: an in vitro study.

In some clinical cases, full-arch impression could be difficult to take correctly with the digital way. Patients with high flow salivary rate or with difficulties in mouth opening can still benefit from a conventional impression with elastomer materials that can be directly or indirectly digitized. The aim of this study was to compare the accuracy and precision of two different intraoral scanners (IOSs) and an impression material with scannable properties, by means of three-dimensional analysis of a complete dental arch. An anatomical model of complete upper arch, modified with a Scan body placed in the retroincisive area, was used. It was firstly scanned by a desktop scanner to create a digital reference model. Then, 3 groups were created, each constituted by 5 samples. In the first group, 5 impressions were taken from the same master model with the scannable PVS material (Hydrorise Implant), 5 scans were taken using Trios4 (3Shape) and other 5 scans with iTero Element 5D (iTero). STL files obtained from IOSs, and scanned impressions were three-dimensionally superimposed on the STL file of the reference model using the Scan body geometry. The ANOVA Test (P<0.005) did not show any statistically significant difference between the accuracy and precision values of the groups. Each group shows clinically acceptable deviations from the reference model. Scannable polyvinylsiloxane impression materials are equally accurate and precise as the two IOSs tested in full-arch dentate impressions.

TIME DEPENDENT EVALUATION OF EFFICACY ON INHIBITION OF BACTERIAL AND FUNGAL GROWTH OF THREE DISINFECTANTS BY IMMERSION AND SPRAYING METHOD ON POLYVINYL SILOXANE IMPRESSION MATERIAL - AN IN-VITRO STUDY

Aim:To determine the efficacy of three disinfectants-2% Glutaraldehyde,0.2% Peracetic acid,70%Isopropyl alcohol with time(3 minutes and 7 minutes) on Staphylococcus Sp. and Candida Sp. on polyvinyl siloxane impression material. Settings and Design:This was an in vitro comparative study. Materials and Methods:A standard inoculum of 0.5 McFarlandwas applied on the prepared polyvinyl siloxane disc surface.Discs were disinfected by immersion and spraying method for 3 minutes and 7 minutes.After that discs were collected in nutrient broth,vortexed and a small volume of the broth was centrifuged.It was thentransferred to test tube containing neutralizing agents of the corresponding disinfectants.0.1 ml from the test tube was transferred to culture plate and incubated to study thesurvivality of Staphylococcus Sp. and Candida Sp. Statistical Analysis Used:One way ANOVAtest was performed to check the mean reduction of microorganism in each group after disinfection by immersion and spraying.Inter group comparison of disinfection efficacy within certain time(3 minutes or 7 minutes) span was done by Tukeys post hoc test. Results:Percentage(%) of mean reduction of staphylococcus and candidas growth obtained from this studywere 99.99% by immersion and spraying method within 3 minutes and 7 minutes. Significance:Both immersion and spraying methods had similar reduction efficacy(99.99%) when compared with control.

Adaptation of Relined Fiber Post Using Discontinuous Short Fiber-Reinforced Resin Composite to Restore Weakened Endodontically-Treated Premolars

Abstract Objective This study aimed to investigate the effect of relining prefabricated fiber-reinforced composite (FRC) posts using bulk-fill, flowable, discontinuous short fiber-reinforced composite (SFRC) on intracanal adaptation in weakened endodontically-treated premolar teeth. Materials and Methods Forty extracted human premolar teeth were selected and randomly allocated to five groups (n = 8) according to the canal preparation method and restorative technique after endodontic treatment: Group 1 (control): nonflared, closed apex root canals; group 2, 4: flared, open-apex root canals; group 3, 5: flared, closed apex root canals. Groups 1 to 3 were restored with standard RelyX fiber post size #1, while groups 4 and 5 were restored with customized RelyX fiber post size #1 and relined with bulk-fill flowable SFRC (everX Flow, GC, Tokyo, Japan). To evaluate intracanal adaptation, the empty root of each sample with the corresponding fiber post (standard or customized) inserted was measured twice using a micro-digital scale and the average value was calculated. The post was then removed, followed by the insertion of a light body polyvinyl siloxane (PVS) impression material into the canal, followed by reinsertion of the post and removal of excess material once the PVS was set. Finally, the sample weight was recorded, and the data were analyzed using one-way analysis of variance and the Bonferroni post hoc test (p-value = 0.05). Results A statistically significant difference (p &lt; 0.05) in PVS material weight was identified between the groups. Group 1 (control) had the lightest weight of PVS material, followed by groups restored with customized fiber posts (groups 4 and 5) and standard fiber posts (groups 2 and 3). Conclusion Anatomically-customized fiber posts with bulk-fill flowable SFRC provided better intracanal adaptation compared with standard fiber posts in teeth with compromised root canals.

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

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

Effect of Plastic Impression-Transfer Copings on the Dimensional Accuracy of Implant Impressions

Purpose: The purpose of this in vitro study was to evaluate the effect of plastic impression transfer copings on the dimensional accuracy of close tray implant impressions. Methods: A master model was constructed using autopolymerizing acrylic resin. Five parallel holes were drilled for implant analogs. Custom impression trays were made with autopolymerizing polymethyl methacrylate resin. The study consisted of 2 groups (n=5): (group 1) Impression was obtained with using plastic impression transfer coping (group 2) Impression was obtained without using plastic impression transfer coping. Vinylpolysiloxane impression material was used for both groups. After the impression were obtained, casts were made by type IV dental stone. Casts were scanned with the lab-type scanner and transferred to the measurement program. Measurements were made from a specific reference corner for each analog to ensure standardization. Data were saved as millimeters and pairwise comparisons were made with Welch's t-test analysis. Results: The effect of plastic caps was evaluated by applying the t-test to each distance. For all distances, the distortion seen in the measurements taken without the cap is higher than the measurements taken with the cap, but no significant differences were found (p&amp;gt;0.05). Conclusions: In the anterior-posterior distances, the distortions were found compression type, in the right-left distances the distortions were found as expansion-type. There is a dimensional change in the measurements taken without a cap, but no clinically significant differences were found.

Comparison accuracy of digital and analog method using milled occlusal splints.

This clinical trial aims to compare the accuracy of interocclusal registration in centric relation taken with polyvinyl siloxane and intraoral scanner (IOS) with the fabrication of occlusal devices. Thirty-one participants were included in the trial registered at ClinicalTrials.gov (NCT05317182) receiving two different occlusal devices from two different workflows. One workflow was performed using polyvinyl siloxane impression material and the other with IOS. Every splint was scanned before and after the occlusal adjustments to compare the volumetric changes using the Root Mean Square deviation (RMS). Furthermore, three evaluators assessed the 3D comparison using color maps in a Visual Analog Scale (VAS). The average values of RMS were higher for the analog approach (0.01 ± 0.067) than the digital approach (0.065 ± 0.035). However, the differences were not statistically significant (p < 0.063) between the two impression techniques. For the semiquantitative analysis performed by blinded evaluators, differences in VAS values between the impression for the digital (2.08 ± 2.4) and analog (3.80 ± 3.3) technique were statistically significant. The three evaluators agreed in more than 90% of the qualitative dichotomous evaluation. Digital impressions did not show inferior accuracy compared to conventional impressions when assessed using quantitative measurements. This clinical trial provided evidence on registering interocclusal relationship at increased vertical dimension with fully digital workflow for complete arch prosthesis.

A COMPARATIVE EVALUATION OF THE EFFECT OF CHEMICAL AND ULTRAVIOLET DISINFECTION ON DIMENSIONAL STABILITY OF POLYVINYL SILOXANE IMPRESSION MATERIAL: AN IN VITRO STUDY

Introduction: In recent advances, ultraviolet (U.V) radiation has proved to be efcacious in killing the microorganisms. Little is known about the effect of this radiation on dimensional stability of addition silicone impression materials, hence a study was conducted to evaluate and compare the effect of U.V disinfection with chemical agents on dimensional stability of polyvinyl siloxane impression material. A total of 60 Materials And Method: samples of PVS impression material were fabricated and divided into 4 groups based on different disinfecting agents i.e. 2% glutaraldehyde, 0.5% sodium hypochlorite and U.V radiation. The impression samples were infected with S.mutans strains , incubated, after which the samples were disinfected, colonies were counted and compared with the control and different disinfectant groups. Following this, the dimensional changes in the samples were evaluated using travelling microscope. Results : Highly signicant results were seen between the number of colonies obtained from control samples and the samples subjected to chemical and U.V disinfection. Whereas in terms of dimensional stability no statistically signicant difference was observed between 2% glutaraldehyde, U.V chamber and 0.5 % sodium hypochlorite. All the disinfect Conclusion: ants tested in this study they can be successfully used for disinfection purpose of Polyvinylsiloxane impression material as they were equally efcacious and did not cause any signicant change on the dimensional stability of PVS impression material.

Comparative Evaluation of Dimensional Accuracy of Autoclavable Polyvinyl Siloxane Impression Material Using Different Methods of Sterilization: An in-Vitro Study

Comparative Evaluation of Dimensional Accuracy of Autoclavable Polyvinyl Siloxane Impression Material Using Different Methods of Sterilization: An in-Vitro Study

Comparative Evaluation of Dimensional Accuracy of Autoclavable Polyvinyl Siloxane Impression Material Using Different Methods of Sterilization: An in-Vitro Study

Comparative Evaluation of Dimensional Accuracy of Autoclavable Polyvinyl Siloxane Impression Material Using Different Methods of Sterilization: An in-Vitro Study