Search Results (7)

Background/Objectives: This study tested a method for evaluating the internal fit of indirect resin-based composite (RBC) restorations, as well as the influence of different combinations of impression and die materials on the reproducibility of the topography of teeth prepared for indirect RBC restoration. Methods: Bovine incisors received flattened and cavitated areas at the cervical and middle thirds of the buccal surface, respectively. The samples were randomly assigned to two groups according to the material used for impression taking (n = 5): irreversible hydrocolloid and polyvinyl siloxane (PVS). Die replicas were obtained with Type IV gypsum or elastomeric material. RBC restorations were fabricated through an indirect technique (test) and a direct-indirect technique as the control. The internal fit of restorations was assessed by measuring the cementation line thickness with a digital caliper (simulated cementation protocol with ultra-light PVS) and validated using scanning electron microscopy (SEM). Surface topography (Sa, Sq, and Sz) was analyzed via optical profilometry, and wettability was assessed through the water contact angle method. The data were analyzed using t-test, ANOVA, and Pearson correlation tests (α = 5%). Results: The simulated cementation resulted in internal gap values positively correlated to the values from SEM (R² = 0.958; p = 0.0102). The internal gap of restorations was not significantly correlated with the discrepancies between the topography of the die and tooth substrate (p ≥ 0.067). The combination of irreversible hydrocolloid and gypsum resulted in restorations with the lowest cementation line thickness, although in terms of roughness, this combination was the only one that resulted in significant differences from the control (p ≤ 0.028). The internal mean gap values of restorations were significantly correlated to the cumulative wettability difference of materials used during impression taking, fabrication of die replica, and restoration build-up (R² = 0.981; p = 0.003). Conclusions: The reproducibility of topographical characteristics of the tooth in the die replica did not affect the internal adaptation of indirect RBC restorations, whereas surface wettability of materials presented a more relevant effect on the overall gap formation. The simulated cementation technique tested in the study shows potential as a simpler, cost-effective, and non-destructive method for evaluating the adaptation of indirect RBC restorations. Full article

Objectives: The study addresses the challenge of cross-infection in dentistry, focusing on improving disinfection protocols for dental hydrocolloid gel materials. This research aimed to incorporate chlorhexidine, natural plant extracts, and green-synthesized silver nanoparticles (AgNPs) into dental alginate to enhance safety and hygiene standards in dental practices. Methods: Conventional dental alginate served as the control, with experimental groups including alginate modified with 0.2% chlorhexidine (CHX-group) and alginate incorporating AgNPs synthesized from Syzygium aromaticum (SA) and Zingiber officinale (ZO) extracts (SA + AgNPs and ZO + AgNPs groups). Plant extracts were analyzed via GC/MS to confirm their composition. UV–visible spectroscopy, SEM, and EDX characterized the synthesized AgNPs. Antimicrobial efficacy against Candida albicans, Streptococcus mutans, and methicillin-resistant and methicillin-sensitive Staphylococcus aureus was evaluated using agar well diffusion assays. The dimensional accuracy of alginate impressions was assessed according to ISO 21563:2021 standards. Results: Chemical analysis of SA and ZO extracts identified 60 and 43 active compounds, respectively, supporting their use in AgNP synthesis. UV–visible spectroscopy, SEM, and EDX confirmed the formation of spherical AgNPs using SA and ZO extracts. Modified groups showed inhibitory activity against Streptococcus mutans and methicillin-resistant (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA), in contrast to the unmodified control. Both AgNP-modified groups demonstrated efficacy comparable to the CHX-group against MRSA and MSSA, with SA + AgNP showing superior performance against C. albicans. The dimensional accuracy of all groups was within clinically acceptable ranges as reported in the literature (0.027–0.083 mm). Discussion: CHX, silver nitrate, and green-synthesized AgNPs present promising options for developing self-disinfecting alginate impression materials. Utilizing plant extracts in AgNP synthesis offers a safe, efficient, and synergistic approach between metal ions and phytotherapeutic agents. This approach could potentially enhance disinfection efficacy without compromising material performance, improving dental safety and hygiene. Full article

Objectives: Impression materials could be a source of cross-contamination due to the presence of microorganisms from blood and saliva inside the oral cavity. Nevertheless, routinely performed post-setting disinfection could compromise the dimensional accuracy and other mechanical properties of alginates. Thus, this study aimed to evaluate detail reproduction, dimensional accuracy, tear strength, and elastic recovery of new experimentally prepared self-disinfecting dental alginates. Methods: Two antimicrobial-modified dental alginate groups were prepared by mixing alginate powder with 0.2% silver nitrate (AgNO₃ group) and a 0.2% chlorohexidine solution (CHX group) instead of pure water. Moreover, a third modified group was examined by the extraction of Boswellia sacra (BS) oleoresin using water. The extract was used to reduce silver nitrate to form silver nanoparticles (AgNPs), and the mixture was used as well in dental alginate preparation (BS + AgNP group). Dimensional accuracy and detail reproduction were examined as per the ISO 1563 standard guidelines. Specimens were prepared using a metallic mold engraved with three parallel vertical lines 20, 50, and 75 µm wide. Detail reproduction was evaluated by checking the reproducibility of the 50 µm line using a light microscope. Dimensional accuracy was assessed by measuring the change in length between defined reference points. Elastic recovery was measured according to ISO 1563:1990, in which specimens were gradually loaded and then the load was released to allow for recovery from the deformation. Tear strength was evaluated using a material testing machine until failure at a crosshead speed of 500 mm/min. Results: The recorded dimensional changes between all tested groups were insignificantly different and within the reported acceptable values (between 0.037–0.067 mm). For tear strength, there were statistically significant differences between all tested groups. Groups modified with CHX (1.17 ± 0.26 N/mm) and BS + AgNPs (1.11 ± 0.24 N/mm) showed higher tear strength values compared to the control (0.86 ± 0.23 N/mm) but were insignificant from AgNO₃ (0.94 ± 0.17 N/mm). All tested groups showed elastic recovery values that met both the ISO standard and ADA specifications for elastic impression materials and tear strength values within the acceptable documented ranges. Discussion: The CHX, silver nitrate, and green-synthesized silver nanoparticles could be promising, inexpensive alternatives for the preparation of a self-disinfecting alginate impression material without affecting its performance. Green synthesis of metal nanoparticles could be a very safe, efficient, and nontoxic method, with the advantage of having a synergistic effect between metal ions and active chemical constituents of plant extracts. Full article

Hydrocolloids are known as natural hydrophilic biopolymers that can contribute viscosity and gelation in solution, as well as nutritional benefits, thus, they are widely used in the food industry. In our work, hydrocolloid was isolated by aqueous extraction of Sesamum indicum seed at 80 °C and pH 8.0. The chemical composition and functional properties of Sesamum indicum seed hydrocolloid (SISH) were characterized, and the effects of concentration including 1%, 2%, and 3% as well as heating/cooling rate (1, 5, and 10 °C/min) on the rheological behavior of SISH dispersions in aqueous solution were investigated. The viscoelastic properties of SISH dispersions were characterized by small-amplitude oscillatory shear measurement. The resultant SISH consisted of 60.95% carbohydrate and 23.32% protein, and was thus endowed with a relatively high water-holding capacity, solubility, appropriate emulsifying and foaming properties. Rheological results revealed that the aqueous dispersion of SISH exhibited a non-Newtonian shear-thinning flow behavior. The viscoelastic moduli changes were found to be dependent on SISH concentration, temperature, and heating/cooling rate. Increasing SISH concentrations from 1% to 3% promoted the development of stronger cross-link network. The mechanical spectra derived from strain and frequency sweep measurements showed that the storage moduli were always higher than the loss moduli, and the loss tangent was calculated to be above 0.1 and below 1.0. Furthermore, both moduli had slight frequency dependency, and the complex viscosity exhibited an almost linear reduction with the increase of frequency. Therefore, SISH dispersion behaved as a weak gel-like system. The hysteresis of viscoelastic moduli during heating and cooling reduced with decreasing the heating-cooling rates from 10 to 1 °C/min, suggesting that SISH molecules had enough time to develop a stable and thermally irreversible network. Overall, SISH can be regarded as an acceptable hydrocolloid for generating natural food components with intriguing functional and rheological qualities in the formulation of microstructured goods. Full article

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. Full article

Hydrocolloids were the first elastic materials to be used in the dental field. Elastic impression materials include reversible (agar-agar), irreversible (alginate) hydrocolloids and synthetic elastomers (polysulfides, polyethers, silicones). They reproduce an imprint faithfully, providing details of a high definition despite the presence of undercuts. With the removal of the impression, being particularly rich in water, the imprints can deform but later adapt to the original shape due to the elastic properties they possess. The advantages of using alginate include the low cost, a better tolerability on the part of the patient, the ease of manipulation, the short time needed for execution, the instrumentation and the very simple execution technique and possibility of detecting a detailed impression (even in the presence of undercuts) in a single step. A comprehensive review of the current literature was conducted according to the PRISMA guidelines by accessing the NCBI PubMed database. Authors conducted a search of articles in written in English published from 2008 to 2018. All the relevant studies were included in the search with respect to the characteristics and evolution of new marine derived materials. Much progress has been made in the search for new marine derived materials. Conventional impression materials are different, and especially with the advent of digital technology, they have been suffering from a decline in research attention over the last few years. However, this type of impression material, alginates (derived from marine algae), have the advantage of being among the most used in the dental medical field. Full article

Irreversible hydrocolloids (IR) is a dental impression material commonly used in Brazilian and European dental practice because it is inexpensive, easy to handle, has good reproductive detail and is comfortable for the patient. This research aimed to analyze the chemical composition of eight different IRs for dental use. A sample of 0.2 g was weighed and transferred to a Teflon beaker moistened with drops of distilled or deionized water; 5 mL of nitric acid was added until total solubility of the sample; the solution was transferred to a 100 mL volumetric flask, the volume was filled with distilled or deionized water and homogenized. Thirty-five chemical elements were found: Lithium, Beryllium, Boron, Sodium, Magnesium, Aluminum, Silicon, Phosphorus, Potassium, Titanium, Manganese, Cobalt, Nickel, Vanadium, Zinc, Rubidium, Arsenic, Iron, Copper, Strontium, Yttrium, Zirconium, Niobium, Molybdenum, Ruthenium, Cadmium, Tin, Antimony, Barium, Lanthanum, Cerium, Mercury, Lead, Thorium and Uranium. Only one of the samples contained no Nickel, Antimony and Lead; and Arsenic and Uranium were found in 2 samples. This study provided evidence of high toxicity of the IR brands, pointing out the need for better quality control of this product, in order to prevent health damage in dentists, prosthesis technicians and patients. Full article