Search Results (32)

Background/Objectives: Maxillary defects, whether congenital or acquired, can compromise chewing, speech, and aesthetics. This systematic review aimed to evaluate the application and characteristics of definitive palatal obturators in the rehabilitation of such defects, analyzing techniques of fabrication, materials, outcomes of the fabrication, and limitations reported in the literature. Methods: The review was conducted in accordance with PRISMA 2020 guidelines and was registered in PROSPERO (ID: 1011648). A comprehensive search was performed in PubMed, Scopus, Lilacs, and Google Scholar for studies published from 1 January 2014 to 1 January 2025. Inclusion criteria comprised adult patients treated with definitive palatal obturators and with reported follow-up. Exclusion criteria included studies on children, animals, or lacking patient data. Two reviewers independently screened studies and assessed eligibility. Bias was evaluated qualitatively across five domains. No meta-analysis was conducted; data were synthesized descriptively using charts and tables. The study was funded by the Italian Ministry of Health—Current Research IRCCS. Results: A total of 59 studies involving 83 patients (46 males, 37 females; mean age 54.6 ± 13.8 years) were included. Mucormycosis and squamous cell carcinoma were the primary causes of defects. Conventional impressions using alginate and silicone were most common, while digital techniques were reported in only 6.6% of cases. All definitive obturators were fabricated using acrylic resin, with some featuring hollow bulbs, velopharyngeal extensions, or magnetic retention. Multiple sources of bias were observed. Conclusions: Definitive palatal obturators provide effective functional and aesthetic rehabilitation for maxillary defects. However, evidence is limited by methodological weaknesses, lack of standardization, and underutilization of digital technologies. Future studies should focus on improving reporting quality, adopting innovative fabrication protocols, and generating higher-level clinical evidence to support best practices. Full article

Background/Objectives: Alginate dental impressions are often among the most anxiety-inducing procedures for pediatric patients due to discomfort caused by nausea, gagging, and the vomiting reflex. This technique frequently raises anxiety levels in children. In contrast, intraoral scanners are increasingly used in clinical practice and offer a more comfortable alternative. Physiological parameters such as heart rate (HR) and oxygen saturation (SpO₂) are useful, objective indicators of anxiety. This study aimed to evaluate significant changes in HR and SpO₂ during dental impression procedures using two techniques—an analog (alginate) and a digital (intraoral scanner) one—in both dental arches, to determine the method inducing the least anxiety. Methods: A non-interventional clinical study was conducted on a sample of 30 children. A fingertip pulse oximeter was used to measure HR and SpO₂ during impression taking with alginate and with an intraoral scanner. Statistical analysis was performed using SPSS^® (Version 30.0. Amonk, NY, USA: IBM Corp). Descriptive statistics (mean and standard deviation) were calculated, and the Friedman and Wilcoxon tests with Bonferroni correction were applied, using a 5% significance level. The study was approved by the Ethics Committee of the University of Murcia. Results: Alginate impressions produced a statistically significant increase in HR in both the upper [(19 ± 11) bpm] and lower [(18 ± 9) bpm] arches compared to the scanner [(7 ± 5) bpm and (7 ± 4) bpm, respectively] (χ² = 49.30; p < 0.001). SpO₂ levels also dropped more when using alginate for both the upper and lower arches [(−2 ± 2)% and (−2 ± 3)%, respectively] than when using the scanner [(−1 ± 1)% in both arches] (χ² = 21.41; p < 0.001). Conclusions: Alginate impressions triggered a significant anxiety response, as evidenced by significant changes in HR and SpO₂. Intraoral scanners were less invasive, as indicated by the greater proximity of the physiological parameters to the baseline values, making them a promising alternative in pediatric dentistry. Full article

Alginate, a polysaccharide found in brown seaweeds, has regularly gained attention for its potential use as a source of bioactive compounds. However, it is structurally complex with a high molecular weight, limiting its application. Alginate oligosaccharides (AOS) are small, soluble fragments, making them more bioavailable. Alginate hydrolysis by enzymes is the preferred method for AOS production. Commercially available alginate lyases are limited, expensive, and sometimes exhibit unsatisfactory activity, making the search for novel alginate lyases with improved activity indispensable. The aims of this study were to codon-optimise, synthesise, express, purify, and characterise a recombinant alginate lyase, AL2, from Flammeovirga sp. strain MY04 and to compare it to a commercial alginate lyase. Expression was successfully performed using Escherichia coli ArcticExpress (DE3) RP cells, and the protein was purified through affinity chromatography. The recombinant enzyme was characterised by pH optimum studies, and temperature optimum and stability experiments. The optimal reaction conditions for AL2 were pH 9.0 and 37 °C, while for the commercial enzyme, the optimal conditions were pH 8.0 and 37 °C. At optimal reaction conditions, the specific activity of AL2 was 151.6 ± 12.8 µmol h⁻¹ mg⁻¹ protein and 96.9 ± 13.1 µmol h⁻¹ mg⁻¹ protein for the commercial alginate lyase. Moreover, AL2 displayed impressive activity in breaking down alginate into AOS. Hence, AL2 shows potential for use as an industrial enzyme for the hydrolysis of alginate into alginate oligosaccharides. Additional studies should be carried out to further characterise this enzyme, improve its purity, and optimise its activity. 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

Cleft lip and palate (CL/P) are a common congenital craniofacial anomaly requiring precise impressions for effective treatment. Conventional impressions (CIs) pose challenges in neonates with CL/P due to their delicate oral anatomy. While digital impressions (DIs) are increasingly recognised for their potential benefits over conventional methods in dentistry, their accuracy and application in neonates with cleft lip and palate (CL/P) remain underexplored. This study aimed to assess the accuracy of DIs compared to CIs in neonates with CL/P, using alginate and putty materials as references. A laboratory-based case–control study was conducted, utilising soft acrylic models resembling neonatal mouths with CL/P. Alginate and putty impressions were obtained conventionally, while digital impressions were captured using an intraoral scanner (IOS). A total of 42 models were analysed, divided evenly into three groups, with each group comprising 14 models. Superimposition and surface discrepancy analyses were performed to evaluate impression accuracy. The results revealed no statistically significant differences between the digital and conventional impressions in their intra-arch measurements and surface discrepancies. The mean measurement values did not significantly differ among groups, with p values indicating no significant variations (p > 0.05), confirmed by an analysis of variance. High intra-examiner reliability with Intra Class Coefficient (ICC) values close to 1 indicated consistent measurements over time. The current study demonstrates that DIs are equally accurate as conventional alginate and putty impressions in neonates with cleft lip and palate, offering a viable and less invasive alternative for clinical practise. This advancement holds promise for improving the treatment planning process and enhancing patient comfort, particularly in vulnerable neonatal populations. Further research is warranted to explore the clinical implications and factors affecting DI accuracy in this population. Full article

Sustainable anode materials, including natural silica and biomass-derived carbon materials, are gaining increasing attention in emerging energy storage applications. In this research, we highlighted a silica/carbon (SiO₂/C) derived from Streblus asper leaf wastes using a simple method. Dried Streblus asper leaves, which have plenty of biomass in Thailand, have a unique leaf texture due to their high SiO₂ content. We can convert these worthless leaves into SiO₂/C nanocomposites in one step, producing eco-materials with distinctive microstructures that influence electrochemical energy storage performance. Through nanostructured design, SiO₂/C is thoroughly covered by a well-connected framework of conductive hybrid polymers based on the sodium alginate–polypyrrole (SA-PPy) network, exhibiting impressive morphology and performance. In addition, an excellent electrically conductive SA-PPy network binds to the SiO₂/C particle surface through crosslinker bonding, creating a flexible porous space that effectively facilitates the SiO₂ large volume expansion. At a current density of 0.3 C, this synthesized SA-PPy@Nano-SiO₂/C anode provides a high specific capacity of 756 mAh g⁻¹ over 350 cycles, accounting for 99.7% of the theoretical specific capacity. At the high current of 1 C (758 mA g⁻¹), a superior sustained cycle life of over 500 cycles was evidenced, with over 93% capacity retention. The research also highlighted the potential for this approach to be scaled up for commercial production, which could have a significant impact on the sustainability of the lithium-ion battery industry. Overall, the development of green nanocomposites along with polymers having a distinctive structure is an exciting area of research that has the potential to address some of the key challenges associated with lithium-ion batteries, such as capacity degradation and safety concerns, while also promoting sustainability and reducing environmental impact. Full article

The aim of the study was to determine potential deviation in measurements of commonly used orthodontic variables, including intermolar width (IMW), intercanine width (ICW), and arch perimeter (AP), when measured on three-dimensional images compared to measurements performed on plaster models obtained from alginate impressions using a hand-held digital vernier caliper. A total of 120 sets of models were divided into four groups: plaster models made from an alginate impression, digitized plaster models made from an alginate and silicone impression, and digital models obtained via intraoral scan. The repeated measurements analysis of variance (ANOVA) with Sidak post-hoc test was applied to test differences in measurements between the four methods. The results show better agreement for intermolar and intercanine width (r = 0.468–0.967) and smaller measurement error (ME = 0.53–1.07) compared to arch length (r = 0.422–0.477; ME = 2.04–2.89). Better agreement levels were more frequently observed between plaster models with intraoral scans than between digitized plaster models. The deviations in intermolar and intercanine width measurements between the hand-held digital vernier caliper and digital analyses were found to be clinically insignificant. The observed difference in arch perimeter suggests that curved measurements may not be clinically acceptable. Full article

The impression materials utilized today in dental medicine offer a good reproducibility and are easily accepted by patients. However, because they are polymer-based, they have issues regarding their dimensional stability. In this respect, the present work proposes a new type of dental impression, which is reinforced with rigid mouthguards. The aim of the study is to test the performances of such new impressions by comparing them to conventional ones—from this critical point of view, of the dimensional stability. Three types of polymeric materials were considered for both types of impressions: alginate, condensation silicone, and addition silicone. In order to obtain the new type of impressions, a manufacturing technique was developed, comprising the following phases: (i) conventional impressions were made; (ii) a plaster model was duplicated, and 15 rigid mouthguards were obtained; (iii) they were inserted in the impression technique, with each mouthguard positioned on the cast before the high-consistency material was inserted in the tray and the practitioner took the impression; (iv) the mouthguard remained in the tray and the low-viscosity material was inserted over the mouthguard; (v) the impression was positioned on the model, and after the material hardened, the mouthguard-reinforced impression was analyzed. In the evaluation of the dimensional stability, rigorous statistical analysis was essential to discern the performance differences between conventional and mouthguard-reinforced dental impressions. Statistical analyses employed non-parametric Mann–Whitney U tests because of the non-normal distribution of the data. They indicated a statistically significant improvement in the dimensional stability of addition silicone impressions when reinforced with mouthguards (p < 0.05), showcasing superior performance over conventional methods. Conversely, alginate and condensation silicone reinforced impressions did not exhibit the same level of stability improvement, suggesting the need for further optimization of these materials. In conclusion, from the three considered elastomers, addition silicone was found to be the prime candidate for high-precision dental impressions, with the potential to improve their quality from conventional impressions by utilizing the proposed reinforcing technique. Full article

The aim of this study was to evaluate the comfort of children and adolescents with conventional full-arch dental impression methods compared to two intraoral scanners (iTero^TM and Primescan^TM). Methods: A monocentric, analytical, controlled crossover study was designed to compare conventional impression and digital impression with two intraoral scanners (iTero^TM and Primescan^TM) in children and teenagers. Patient comfort was evaluated using a 100 mm VAS scale adapted to Spanish and for children. A descriptive and analytical statistical method was conducted with a confidence level of 95% (p ≤ 0.05) and asymptotic or bilateral significance. Results: A total of 51 subjects were enrolled in the study (mean age = 12.35 years). Although the group of 10–14-year-olds was the most numerous, gender was equally distributed among the age groups. None of the variables on the VAS scale showed differences between the gender categories (p > 0.05). There were differences (p < 0.05) with respect to the age categories, as the middle adolescent group showed the worst general perception and total comfort during the conventional impression. Statistically significant differences were found between all VAS scale items and the three impression methods (p < 0.05). Conclusions: The digital impression technique is superior in terms of total comfort to the conventional alginate impression in children and adolescents. Full article

(1) Background: The objective of this study was to assess which digitization method produces the biggest deviation in the 3D images of tooth size from plaster models made using alginate impressions, which are considered the gold standard in orthodontics. (2) Methods: The sample used in this study included 30 subjects (10 males and 20 females). Measurements were made on four types of models: (1) digital models obtained through intraoral scanning and digitized models of plaster cast made from (2) alginate impressions, (3) silicone impressions, and (4) conventional plaster models. Mesio-distal (MD) and buccal/labial–lingual/palatal (BL) dimensions were measured on the reference teeth of the right side of the jaw (central incisor, canine, first premolar, and first molar). Comparisons of tooth size between the methods were conducted using a repeated measurement analysis of variance and the Friedman test, while the intraclass correlation coefficient was used to determine agreement between the different methods. (3) Results: The results showed a similar level of agreement between the conventional and digital models in both jaws and the anterior, middle, and posterior segments. Better agreement was found for the MD measurements (r = 0.337–0.798; p ≤ 0.05) compared to the BL measurements (r = 0.016–0.542), with a smaller mean difference for MD (0.001–0.50 mm) compared to BL (0.02–1.48 mm) and a smaller measurement error for MD (0.20–0.39) compared to BL (0.38–0.89). There was more frequently a better level of agreement between 3D images than measurements made using a digital caliper on the plaster models with 3D images. (4) Conclusions: The differences in measurements between the digital models and conventional plaster models were small and clinically acceptable. Full article

Disinfection of alginate impressions used in dental prosthetics is a very problematic procedure, during which the dimensions of the obtained model can change, and it can be easily mechanically damaged. Therefore, it would be beneficial to create a material with bacteriostatic properties for this application. In this work, we investigated alginate materials with the addition of 0.25–1.0 wt% of zirconium phosphate-based ion exchange resin containing silver and compared them with commercial alginate impression products. The obtained materials passed the normative requirements of ISO 21563:2021 (setting time, elastic recovery, strain in compression, compatibility with gypsum, detail reproduction, tearing strength, and linear dimensional change) as well as bacteriostatic properties in relation to Streptococcus mutans. The newly developed alginate materials met all the properties required by the standards. Their setting time was comparable to the commercial materials, and their 24 h contraction did not exceed 1.3%. Furthermore, the tearing strength was 0.42–0.48 MPa, less than that of the comparative commercial materials (0.52–0.56 MPa). From the point of view of clinical practice, it will be possible to create an alginate material with bacteriostatic properties that will prevent the transmission of cross-infections. 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

This study aimed to investigate the transfer accuracy and required time for digital full-arch impressions obtained from intraoral scanners (IOSs) versus conventional alginate impressions (CAIs) in patients with multibracket appliances (MBA). Thirty patients with buccal MBAs (metal brackets, archwire removed) were examined using an established reference aid method. Impression-taking using four IOSs (Primescan, Trios 4, Medit i700, Emerald S) and one CAI with subsequent plaster casting were conducted. One-hundred-twenty (n = 30 × 4) scans were analyzed with 3D software (GOM Inspect) and 30 (n = 30 × 1) casts were assessed using a coordinate measurement machine. Six distances and six angles were measured and compared to the reference aid values (ANOVA; p < 0.05). Except for the intermolar distance, transfer accuracy was significantly higher with IOSs than with CAIs (p < 0.05). No such difference was found regarding the six angles. In patients with MBAs, digital impression-taking using IOSs can be recommended. For all measured variables except one, the transfer accuracy of IOSs was better than or at least equivalent to the data from CAIs. In addition, significantly (p < 0.001) less time was necessary for all IOSs in comparison to CAIs plus plaster casting. Full article

During impressions, bacteria, viruses, and fungi remain on the impression material, representing a significant risk for the medical team (dentists, dental assistants, and laboratory technicians). Impression disinfectants have been introduced into dentistry to reduce the risk of cross-infection. This study was performed by examining the surface disinfection of five commonly used impression materials in prosthodontics: alginate-Tropicalgin (Zhermack^®), condensation silicone-Zetaplus (Zhermack^®), Oranwash L (Zhermack^®); and addition silicone-Elite HD + Putty Soft (Zhermack^®), Elite + Light Body (Zhermack^®) after the disinfection with three disinfectants: Zeta 3 Soft (Zhermack^®), Zeta 7 Spray (Zhermack^®) and Zeta 7 Solution (Zhermack^®). Before disinfection, the impression materials were contaminated with Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10213. Our results demonstrate the efficacy of the two examined specific disinfectants in reducing cross-infection risk. The surface disinfectant-spray is not adequate for impression disinfection. A high number of bacterial colonies were found on the surface of all impressions disinfected with this spray. The immersion-disinfection method effectively eliminates the risk of cross-infections (Kruskal–Wallis test showed a p < 0.001). Full article

Impression materials are used to record and reproduce the exact morphology of the patient’s oral cavity. The dimensional stability of a material is its ability to maintain the accuracy of recording the details of the oral cavity for a longer period of time, including the time during imprinting and immediately after. The aim of this study was to evaluate the accuracy of three different impression materials commonly used in the dental practice with the aid of an extra-oral three-dimensional (3D) scanner using an in vitro analysis. A typodont tooth model of the maxillary dental arch and mandibular dental arch, containing 16 permanent teeth, was used for evaluation. With the aid of three different impression materials, this model was imprinted fifteen times, resulting in fifteen different plaster models. A capsule extra-oral scanner device was used to digitalize the models and the same device was later used to align, compare, and measure scanned model surfaces. After performing the Kruskal–Wallis test for each measurement category (model), only two out of the fifteen measurements showed statistically significant differences between the material groups: vestibular-oral and mesial-distal width. Post hoc analysis showed that the alginate model (mean range = 29.13) had significantly higher bias scores than the addition silicone model (mean range = 16.75) (z = 2.501, p = 0.037). The difference between the average values of the model bias made from condensation-based silicone and addition-based silicone was initially significant, but after applying the Bonferroni correction for further comparisons, this relationship did not remain significant (z = 2.197, p = 0.084). Addition-based silicone models had the highest accuracy in terms of fidelity, followed by condensation-based silicones, and then by alginate models. Silicone-based impression materials improved over time, being highly used in all areas of dentistry. Alginate impressions had the lowest pattern of accuracy among those studied. Full article