A Promising Potential of Brown Algae Sargassum polycystum as Irreversible Hydrocolloid Impression Material

This study aimed to investigate the potential use of brown algae Sargassum polycystum as irreversible hydrocolloid (alginate) impression material. Potassium alginate extracted from Sargassum polycystum was prepared in three different compositions (14%, 15%, and 16%) and mixed with other standard components to form an alginate impression material. Prior to that, the purity of potassium alginate was quantified with Fourier Transform Infrared Spectroscopy (FTIR) analysis. As a control material, the alginate impression material from a commercially available product was used. All alginate impression materials were then applied to a die stone model. Dimensional accuracy was measured by calculating the mesiodistal width of incisors in the generated dental cast using a digital caliper 0.01 accuracy (five replications). In addition, to evaluate the dimensional stability, the impression results were poured at four different periods (immediately, 5 min, 10 min, and 15 min). An independent t-test was performed to compare the measurement results with p < 0.05 considered significant. Analytical results confirm that the impression material containing 15% potassium alginate gives the best dimensional accuracy similar to control (p > 0.05). Meanwhile, the optimal dimensional stability was produced in the impression material containing 16% potassium alginate. Our study suggested that brown algae Sargassum polycystum has a promising potential to be used as an alginate impression material in clinical application.

Dimensional Stability of Elastomeric Impression Material After Disinfection Via Immersion and Microwave Irradiation

Aims: This study aimed to evaluate and compare the dimensional stability of two elastomeric impression materials, namely polyvinyl siloxane (PVS) and vinyl siloxanether (VSE), subjected to chemical immersion and microwave irradiation for disinfection. Materials and Methods: Sixty discs of PVS and VSE impression materials each were prepared using a stainless-steel test die and ring in accordance with ANSI/ADA Specification No. 19. Twenty discs of each impression material were disinfected by chemical immersion for 10 min; another 20 discs were subjected to dry microwave irradiation for 3 min. The other 20 discs served as a control group. Dimensional stability measurements were then performed using an image analyzer at 20× magnification. The data were analyzed by one-way analysis of variance (α=0.05) and Bonferroni (post hoc) test for multiple comparisons to detect significant differences between the groups. Results: When subjected to microwave irradiation, both PVS and VSE showed dimensional changes, but the changes were within the limit of 1.5% set by ANSI/ADA (P<0.00). VSE showed markedly better results than PVS for both disinfection methods. The immersion disinfection method resulted in a higher average percentage of linear dimensional changes than both the microwave irradiation and the control for VSE and PVS impression materials. Conclusion: VSE exhibited excellent dimensional stability than PVS under both chemical immersion and microwave irradiation. Microwave irradiation using conventional microwave ovens can be used in clinical settings as an alternative to other disinfection techniques because the dimensional changes of the elastomeric impression materials subjected to microwave irradiation have been observed to be within the clinically acceptable limit set by the ANSI/ADA standard.

THE EFFECT OF 25% BELT LEAVES AND 0.2% CHLORHEXIDINE AS DISINFECTANT MATERIALS ON THE DIMENSIONAL STABILITY OF ALGINATE MOLDS

ntroduction: Dental impression material is one of the agents of infection transmission in the dentist's work environment. Cross infection can occur through the interaction of microorganisms and impression material. To prevent cross infection, it is necessary to disinfect alginate impressions. One of the effective natural ingredients that can be used as a disinfectant is betel leaf. The effect of using disinfectant can affect the dimensional stability of the alginate mold. Purpose: This study aims to determine the effect of disin- fection by spraying a decoction of 25% betel leaf and 0.2% chlorhexidine on the dimensional stability of alginate molds. Materials and Methods: The research method used was an experimental laboratory with a post-test only control g roup design using 2 7 samples consisting of three treatments (negative control group, positive control group, and treatment group) which were measured using a digital caliper. The technique us ed in this study is the spraying technique on the sample with a st orage time of 10 minutes. Results and discussion: This 25% betel leaf de coction (infusion) can be used as an alternative to disinfecting alginate impressions because there is no difference in effect between spraying 25% betel leaf decoction (infusion) and 0.2% chlorhexidine on alginate molds on changes in model physiological dimen- sions. Conclusion: the dimensional changes that occur are still within tolera- ble limits in alginate molds which were disinfected by spraying 25% betel leaf decoction and 0.2% chlorhexidine solution so that both can be used as disinfection materials for alginate impression materials

Minimizing the risk of fracture of definitive casts for removable partial dentures: A dental technique

A technique is described to facilitate impression making and safely obtain the definitive cast for removable partial dentures with long, retentive, or lone-standing abutment teeth. Firstly, the individualized stock tray receives a coating of melted wax. Next, the prepared teeth are impressed with irreversible hydrocolloid, and the set impression is removed from mouth. The mold is then poured conventionally and, after the gypsum has set, is immersed in hot water to soften the wax and allow removal of the tray. The impression material is carefully cut away with a scalpel blade to expose the cast. With these straightforward and easily made changes compared with the conventional technique, the risk of fracturing the definitive cast is minimized, especially when reproducing long retentive teeth. A dental technique is presented that uses wax to coat the impression tray to facilitate the passive displacement of the cast. This results in a straightforward and precise definitive cast for removable partial dentures.

Accuracy of Impression Material During COVID-19 after Sterilization- In vitro Study

Aims: The goal of this research is to assess the effect of steam autoclave sterilization due to the impact of Covid-19 on the accuracy of the elastomer impression materials. Study Design: In vitro study. Place and Duration of Study: Department of oral and Maxillofacial Prosthodontics, King Abdul-Aziz University, Jeddah; Saudi Arabia, between June 2021 and November 2021. Methodology: The following materials were used in this study: fully dentate master cast, metal trays, elastomer impression material (addition silicon), type IV stone. Forte impressions made using the metal tray and elastomer impression materials. The impressions were separated equally into two groups: Control group (C.G), untreated impressions. Sterilized group (S.G): Impressions were sterilized by using the steam autoclave. To make stone castings for each group, they were poured with type IV stone. The traveling microscope was used to evaluate the impression material's dimensional accuracy and detail reproduction with and without autoclave sterilization. Results: The cross-arch distance (X) of the master model was measured (41.29 mm), While the cross arch distance (X) in the control group (C.G) of the untreated impressions had a mean and standard deviation of 41.492 ± 0.150 mm. In the tested group (S.G) : the sterilized impression, we found the cross-arch distance (X) had a mean and standard deviation of 41.628 ± 0.223 mm. The master model's Anteroposterior distance (A-P) was measured (21.12 mm). For the control group (C.G) : we found the mean and standard deviation value reading of the A-P distance were 20.899 ± 0.79 mm. For (S.G) group: we found the mean and standard deviation reading of the A-P distance were 19.992± 0.482 mm. Conclusion: Steam autoclave sterilization of the elastomer impression material should be considered carefully, especially when fabricating fixed partial dentures. If the impression material is to be used in making diagnostic castings, conventional steam autoclave sterilization of the elastomers impression material may be sufficient for patients.

Accuracy of the Intra- and Extra-Oral Scanning Technique for Transferring the Intaglio Surface of a Pontic of Provisional Restorations to Definitive Restorations

When taking the final impression for a three-unit fixed partial denture (FPD), the intaglio surface of the pontic of provisional restoration cannot be transferred accurately to that of definitive restoration. The intra- and extra-oral scanning (IEOS) technique, a method for accurately reproducing the submucosal morphology of the superstructure of an implant, has been reported using an intraoral scanner. In the present study, we evaluated the difference between the conventional impression method using impression material and the IEOS technique in reproducing the morphology of the surface of the pontic of a definitive FPD. There was a significant difference in the trueness of the intaglio surface morphology of the pontic between the conventional method and the IEOS technique; however, no significant difference in precision was observed. As a result, the intaglio surface of the pontic of the three-unit FPD could be transferred to definitive restorations more accurately with the IEOS technique than with the conventional method. These results suggest that the IEOS technique can duplicate the intaglio surface of the pontic more reproducibly to the definitive restorations compared with the conventional method.

Comparing the Dimensional Accuracy of Casts Obtained from Two Types of Silicone Impression Materials in Different Impression Techniques and Frequent Times of Cast Preparation

Introduction. The dimensional accuracy of casts is essential in the quality of fixed prosthesis treatment, whereby the impression method is a very crucial factor affecting it. The aim of this in vitro study is to compare the dimensional accuracy of casts resulting from two types of silicone impression materials in different impression techniques and frequent times of cast preparation. Materials and Methods. A metal model was made from two prepared abutments, and 10 casts were prepared from each material technique (n = 40). The impressions were made by condensation and addition silicone (one-stage and two-stage impressions). The casts were made from same impressions 1 h, 24 h, and 14 days. The diameter, height, and the distance between two dies were recorded. Data were analyzed by repeated measure ANOVA (P value <0.05). Results. The dimensional accuracy of all four materials techniques of impression (diameter, height, and the distance between dies) was the same in different times of impression. Dimensional accuracy of the die diameter and distance between dies in one-stage (Speedex) condensation silicon and one-stage (Panasil) addition silicone did not differ significantly, and their one-stage method developed more accurate casts compared to the two-stage method of the same impression material. The height of the casts prepared from the one-stage method through Speedex and Panasil did not differ significantly from the two-stage method of the same impression material. Conclusion. One-stage condensation silicone and one-stage addition silicone material techniques offered the maximum dimensional accuracy in the obtained casts. The time of impression did not have any significant effect in the accuracy of any of the four impression material techniques.

The effect of contact time between alginate impression material and type III dental stone on the surface properties of stone casts

Background: Alginate impression material is the irreversible hydrocolloid material that is widely used in dentistry. The contact time between alginate and gypsum cast could have a detrimental effect on the properties of the gypsum cast. The objective of this study is to evaluate the impact of various contact time intervals of Alginate impressions & type III dental stone on surface properties of stone cast. Materials and Methods: Time intervals tested were 1hour, 6 hours and 9 hours. Surface properties of stone cast evaluated were surface detail reproduction, hardness and roughness. Surface detail reproduction was determined using cylindrical brass test block in accordance with ISO 1563. Surface roughness was measured by profilometer and hardness was measured by Durometer (Shore D). Results: The detail reproduction showed significant difference (P<0.05), at 6 hr., and 9 hr. showed better results. While surface roughness significantly decreased (p<0.01) with prolonged contact time. However, surface hardness increased significantly (p<0.01) with increased contact time. Conclusions: Surface detail reproduction increased with increasing the contact time and this was noticed at (6, 9 hours). However, 1hour time interval showed decreased surface detailed reproduction. Roughness decreased when the contact time was increased between type III dental stone and alginate impression whereas, hardness was improved significantly with increasing contact time.

Influence of expiration date on detail reproduction of dental elastomers

Elastomers are synthetic rubber materials formed by polymers, which are joined by a small number of cross-links that form a three-dimensional network. The aim of the current study was to compare the surface detail reproduction of polyvinyl siloxane and polyether-based elastomeric impression materials (2 years after their expiration date) to the ones that have not exceeded this period-of-time. Four groups comprising 5 samples, each (n = 5), were divided based on material (polyvinyl siloxane – Express and polyether – Impregum Soft) and expiration date (expired, or not). The manipulated material was placed on a tray in a way to fully cover its inner part. Later on, it was placed on a metal matrix presenting 20-, 50- and 75-μm lines. Molds were removed after polymerization and surface detail reproduction was measured in comparator microscope (Stereozoom Microscope), along the 20 μm line (25 mm in length), at 4x-magnification, in compliance with ISO 4823. Surface detail reproduction values were subjected to descriptive analysis - results were expressed in percentage (%). All groups presented 100% of surface detail reproduction, regardless of impression material or expiration date. Surface detail reproduction of the investigated materials was not influenced by the evaluated elastomers’ expiration date.

Flabby Ridge, a Challenge for Making Complete Dentures

In the case of old mobile denture wearers, one of the main problems is related to the dentures’ retention and insufficient stability. Our goal was to improve support and stability using a different type of final impression, with different types of impression materials. In this study we chose a number of three complete edentulous patients who presented for complete oral rehabilitation. They were wearing full acrylic dentures with poor support and stability. Complete examination revealed the presence of the flabby ridge. The impression methods for the prosthetic fields with a flabby ridge differ from the classical method by using techniques that involve the use of at least two impression materials with fluid consistency to record all the details of the prosthetic fields in the final impression, this being done in two steps; the impression of the flabby ridge areas must be done without pressure, in its resting position. The impression methods we applied led to the expected results, and the dentures succeeded in offering the patient the desired functional comfort. Using fluid impression material for the flabby ridge in a resting position, and a fenestrated custom tray, offered a good quality in adaptation, maintenance and stability of the final dentures.