The trends of dental biomaterials research and future directions: A mapping review

In Vitro Cytotoxicity Evaluation of Nanosized Hydroxyapatite and Fluorapatite on Cell Lines and Their Relevance to the Alveolar Augmentation Process

Background/Objectives: Materials with an apatite structure were investigated in vitro in dental bone augmentation procedures. This scientific study aimed to compare nanosized hydroxyapatite (nHAp) and fluorapatite (nFAp) materials in the form of tablets in in vitro studies, including cytotoxicity assessment and fluoride release. Methods: The nHAp and nFAp nanosized materials were obtained using the microwave hydrothermal method. Subsequently, the tablets were prepared from these nanosized powders as further studied materials. Cytotoxicity tests were conducted on Balb/3T3 fibroblast cells and L929 cells. Fluoride ion release was tested at 3, 24, 48, 72, and 168 h periods. Results: Both materials presented viability levels above 70%, indicating a lack of cytotoxic potential. The amount of fluoride (F-) ions released and accumulated from nFAp was greatly higher than from nHAp. The release of F- ions in both samples was the highest in the first 3 h of exposition. The accumulation of F- ions reached the highest values in the deionized water. The most significant differences in the released or cumulated fluoride ions were observed between deionized water and lower 4.5 pH AS (artificial saliva) samples. Conclusions: Both nanosized hydroxyapatite and fluorapatite materials are biocompatible, and their in vitro examination showed promising results for their future in vivo application.

Valorization of crop by-products into bio-based dental materials: advancements and prospects

The objective of this review is to deepen understanding and emphasize scientific and technological progress in the transformation of crop by-products into bio-based dental materials. Amid heightened environmental sustainability consciousness, various sectors including dentistry have achieved novel advancements by utilizing bio-based materials from crop by-products for dental restorations. This paper provides a thorough review of the extraction, processing, and application of natural polymers, biopolymers, and bio-based mixtures at both the macroscopic and nanoscopic scales, with a focus on their contextualization within dental practices. The performance and efficacy of bio-resins, bio-sourced monomers, and biopolymers derived from these resources were scrutinized and compared with traditional petroleum-based counterparts. This study addresses the recycling and industrial valorization of bio-based dental materials, emphasizing their potential to foster a circular economy in dentistry.

Streptococcus-mutans and Porphyromonas-gingivalis adhesion to glazed/polished surfaces of CAD/CAM restorations

Purpose

Dental restorations fabricated using CAD/CAM require modification/adjustment before cementation. Streptococcus mutans (S.mutans) and Porphyromonas gingivalis (P.gingivalis) are prevalent bacterial species that may adhere to these materials and can cause caries, gingivitis/periodontitis. The purpose of this in vitro study was to evaluate the bacterial adherence of S.mutans and P.gingivalis to five different kinds of modern CAD/CAM restorative materials with different compositions following chairside finishing/polishing and glazing.

Materials and methods

Specimens (N = 75) from five test materials (n = 15 each) "Tetric-CAD®; IPS-e.max-CAD®; IPS-e.max-ZirCAD®; CELTRA-Duo® and Vita-Enamic®" were prepared in disc shape (10 × 3 mm) using CAD/CAM. The specimens underwent glazing and finishing/polishing using established procedures. The surface roughness was measured in micrometers (μm) using a profilometer. Bacterial adherence to test materials' glazed and finished/polished surfaces was tested using bacterial culture growth over the test materials. Data obtained was tabulated and statistical analysis performed using Kruskal Wallis test, post-hoc Conover test, Mann-Whitney U test and Tukey post hoc test.

Results

With the exception of IPS-e.max-ZirCAD®, which showed the contrary, the adherence of S.mutans & P.gingivalis was less on glazed surfaces compared to finished/polished surfaces for four test materials: "Tetric-CAD®, IPS-e.max-CAD®, CELTRA-Duo®, and Vita-Enamic®". On the glazed surfaces, the adhesiveness of S.mutans and P.gingivalis was not significant (p = 0.099; p = 0.660); however, on the finished/polished surfaces, it was significant (p = 0.002; p = 0.004). With the exception of 'IPS-e.max-ZirCAD®', which showed the reverse behavior, the adhesion of S.mutans & P.gingivalis to finished/polished surfaces was greater for each of the four ceramics under investigation "Tetric-CAD®, IPS-e.max-CAD®, CELTRA-Duo®, and Vita-Enamic®".

Conclusion

Glazed surfaces for majority of test materials demonstrated decreased adhesion from S.mutans & P.gingivalis, hence prior to final placement of restoration, it is advised to adhere to the minimal glazing criteria. Regardless of the chemical composition of the materials, the surface texture of the tested materials significantly influenced bacterial adhesion.

Food-Oral Processing: Current Progress, Future Directions, and Challenges

Oral processing refers to the series of physical, chemical, and biological processes inside the oral cavity when we consume food. This process affects the taste, quality, and nutrient absorption of the body. In the human diet, oral processing plays a crucial role because it impacts not only the food flavor and texture but also the absorption and utilization of nutrients. With the progress of science and technology and the increasing demand for food, the study of oral processing has become increasingly important. This paper reviews the history and definition of oral processing, its current state of research, and its applications in food science and technology, focusing on personalized taste customization, protein structure modification, food intake and nutrition, and bionic devices. It also analyzes the impact of oral processing on different types of food products and explores its potential in the food industry and science research.

The Shear Bond Strength of Resin-Based Luting Cement to Zirconia Ceramics after Different Surface Treatments

Due to its unique properties, zirconia is increasingly being used in dentistry, but surface preparation for bonding is difficult because of its polycrystalline structure. This study aimed to determine the effect of a new etching technique (Zircos-E) on Ceramill Zi (Amann Girrbach). The effect of etching and the use of primers (Monobond Plus and MKZ Primer) on the bond strength of zirconia with resin cement (NX3) was assessed. Shear bond strength was evaluated after storage in water for 24 h and after thermal aging (5000 thermocycling at 5 °C/55 °C). A scanning electron microscope (Hitachi S-4700) was used to evaluate the surface structure before and after the Zircos-E system. The roughness parameters were assessed using an SJ-410 profilometer. The etched zirconia surface is more homogeneous over the entire surface, but some localized forms of erosion exist. The etching of zirconia ceramics caused changes in the surface structure of zirconia and a significant increase in the shear bond strength between zirconia and resin cement. The use of primers positively affects the adhesion between resin cement and zirconia. Aging with thermocycler significantly reduced the shear bond strength, with one exception-sandblasted samples with MKZ Primer. Standard ceramic surface preparation, involving only alumina sandblasting, does not provide a satisfactory bond. The use of etching with the Zircos-E system and primers had a positive effect on the strength of the zirconium-resin cement connection.

Bioactive Restorative Materials Applied over Coronal Dentine-A Bibliometric and Critical Review

The objective of the research was to examine the scientific literature concerning restorative materials with bioactive properties for the purpose of covering dentin. Searches were performed in various databases including MEDLINE, Scopus, Web of Science, Cochrane Library, Lilacs/BBO, and Embase. Inclusion criteria involved studies that utilized the terms "dentin" and "bioactive", along with "ion-releasing", "smart materials", "biomimetic materials" and "smart replacement for dentin". The information extracted included the title, authors, publication year, journal and the country of affiliation of the corresponding author. The studies were categorized based on their study design, type of material, substrate, analytical method, and bioactivity. A total of 7161 records were recovered and 159 were included for data extraction. Most of the publications were in vitro studies (n = 149), testing different types of materials in sound dentine (n = 115). Most studies were published in Dental Materials (n = 29), and an increase in publications could be observed after the year 2000. Most of the articles were from the USA (n = 34), followed by Brazil (n = 28). Interfacial analysis was the most investigated (n = 105), followed by bond strength (n = 86). Bioactivity potential was demonstrated for most tested materials (n = 148). This review presents insights into the current trends of bioactive materials development, clearly showing a severe lack of clinical studies.

Morphological Interface Between Restorative and Pulp-Capping Materials: A Systematic Review

Background

Bioceramic materials (BCMs) are widely used in vital pulp therapy (VPT) for their biocompatibility and bioactivity; however, their mechanical properties are equally important in the clinical outcome of the pulp-capped teeth.

Objective

To carry out an analysis of the research produced on the morphology of the interface between BM and restorative materials (RM) through a systematic review.

Methodology

An electronic search was performed in Scopus, PubMed, and Web of Science until December 9, 2022. The keywords used in combination with truncation and Boolean operators were: (morphology OR filtration OR porosity) AND (silicate OR composite) AND (cement) AND ("pulp capping" OR "vital pulp therapy" OR "vital pulp treatment").

Results

Of the 387 articles initially retrieved from the electronic search databases, 5 articles met the criteria for qualitative data collection. MTA and Biodentine were the most studied BCMs. All the articles used a scanning electron microscope as a method of evaluating the samples. Sample sizes and setting times of RM and BCMs differed between studies. Three out of 5 studies used similar conditions of recorded temperature and humidity of 37°C and 100%, respectively.

Conclusion

The different biomaterials used, the application of adhesive systems, humidity and restoration time affect the bonding performance and the ultrastructural interface between BCMs and RMs. The scarcity of research on this point makes it necessary to delve into it and study new materials to obtain more scientific evidence.

In Vitro Optical and Physical Stability of Resin Composite Materials with Different Filler Characteristics

The objective of this study was to compare the physical and optical stability of resin composite materials with different filler characteristics. Ninety-six resin composite blocks (6 mm × 6 mm × 2 mm) were prepared using four different types of resin composite, divided into four groups. Specimens from the same material were randomly divided into four groups (n = 6) and allocated for Vickers hardness (VH), water sorption, solubility (WS/SL), and staining and aging challenges tests. One-way ANOVA showed significant differences in microhardness (p = 0.0001), WS (p = 0.0001), and SL (p = 0.003) among the tested groups. Beautifil II LS recorded the highest hardness, and CharmFil^®Flow had the lowest value. Beautifil Injectable X and II LS showed negative WS, whereas the other groups had positive values. All groups showed positive SL. Repeated measures ANOVA showed significant color parameter alteration in the tested groups (p = 0.0001). All groups showed significant color shifting after one week of the staining challenge. Repeated measures ANOVA showed a significant color parameter (p = 0.0001) and weight (p = 0.001) alteration after the aging challenge. The optical and physical stability of resin composites may vary according to filler characteristics. Clinicians should choose the composite as per the desired outcome.

Sol-gel synthesis of lithium doped mesoporous bioactive glass nanoparticles and tricalcium silicate for restorative dentistry: Comparative investigation of physico-chemical structure, antibacterial susceptibility and biocompatibility

Introduction: The sol-gel method for production of mesoporous bioactive glass nanoparticles (MBGNs) has been adapted to synthesize tricalcium silicate (TCS) particles which, when formulated with other additives, form the gold standard for dentine-pulp complex regeneration. Comparison of TCS and MBGNs obtained by sol-gel method is critical considering the results of the first ever clinical trials of sol-gel BAG as pulpotomy materials in children. Moreover, although lithium (Li) based glass ceramics have been long used as dental prostheses materials, doping of Li ion into MBGNs for targeted dental applications is yet to be investigated. The fact that lithium chloride benefits pulp regeneration in vitro also makes this a worthwhile undertaking. Therefore, this study aimed to synthesize TCS and MBGNs doped with Li by sol-gel method, and perform comparative characterizations of the obtained particles.

Methods: TCS particles and MBGNs containing 0%, 5%, 10% and 20% Li were synthesized and particle morphology and chemical structure determined. Powder concentrations of 15mg/10 mL were incubated in artificial saliva (AS), Hank’s balanced saline solution (HBSS) and simulated body fluid (SBF), at 37°C for 28 days and pH evolution and apatite formation, monitored. Bactericidal effects against S. aureus and E. coli, as well as possible cytotoxicity against MG63 cells were also evaluated through turbidity measurements.

Results: MBGNs were confirmed to be mesoporous spheres ranging in size from 123 nm to 194 nm, while TCS formed irregular nano-structured agglomerates whose size was generally larger and variable. From ICP-OES data, extremely low Li ion incorporation into MBGNs was detected. All particles had an alkalinizing effect on all immersion media, but TCS elevated pH the most. SBF resulted in apatite formation for all particle types as early as 3 days, but TCS appears to be the only particle to form apatite in AS at a similar period. Although all particles had an effect on both bacteria, this was pronounced for undoped MBGNs. Whereas all particles are biocompatible, MBGNs showed better antimicrobial properties while TCS particles were associated with greater bioactivity.

Conclusion: Synergizing these effects in dental biomaterials may be a worthwhile undertaking and realistic data on bioactive compounds targeting dental application may be obtained by varying the immersion media.

Bioceramics in Endodontics: Updates and Future Perspectives

Bioceramics, with excellent bioactivity and biocompatibility, have been widely used in dentistry, particularly in endodontics. Mineral trioxide aggregate (MTA) is the most widely used bioceramic in endodontics. Recently, many new bioceramics have been developed, showing good potential for the treatment of endodontic diseases. This paper reviews the characteristics of bioceramics and their applications in various clinical endodontic situations, including root-end filling, root canal therapy, vital pulp therapy, apexification/regenerative endodontic treatment, perforation repair, and root defect repair. Relevant literature published from 1993 to 2023 was searched by keywords in PubMed and Web of Science. Current evidence supports the predictable outcome of MTA in the treatment of endodontic diseases. Although novel bioceramics such as Biodentine, EndoSequence, and calcium-enriched mixtures have shown promising clinical outcomes, more well-controlled clinical trials are still needed to provide high-level evidence for their application in endodontics. In addition, to better tackle the clinical challenges in endodontics, efforts are needed to improve the bioactivity of bioceramics, particularly to enhance their antimicrobial activity and mechanical properties and reduce their setting time and solubility.

Aspects and Principles of Material Connections in Restorative Dentistry-A Comprehensive Review

The combination of two dissimilar materials has always been a serious problem in dentistry. In order to meet this challenge, it is necessary to combine both chemical methods (treatment with silanes, (meth)acrylic functional monomers) and the development of the surface of the joined material in a physical way, e.g., by sandblasting with alumina, alumina with silica, acid etching, the use of lasers and other means. The purpose of this literature review is to present all methods of joining dental composites with other materials such as ceramics, metal, another composite material. This review covers articles published within the period 2012-2022 in journals indexed in the PubMed database, written in English and describing joining different dental materials to each other. All the critical steps of new joint preparation have been addressed, including proper cleaning of the joint surface, the application of appropriate primers capable of forming a chemical bond between ceramics, zirconium oxide or metals and alloys, and finally, the application of new composite materials.

Bioactive Inorganic Materials for Dental Applications: A Narrative Review

Over time, much attention has been given to the use of bioceramics for biomedical applications; however, the recent trend has been gaining traction to apply these materials for dental restorations. The bioceramics (mainly bioactive) are exceptionally biocompatible and possess excellent bioactive and biological properties due to their similar chemical composition to human hard tissues. However, concern has been noticed related to their mechanical properties. All dental materials based on bioactive materials must be biocompatible, long-lasting, mechanically strong enough to bear the masticatory and functional load, wear-resistant, easily manipulated, and implanted. This review article presents the basic structure, properties, and dental applications of different bioactive materials i.e., amorphous calcium phosphate, hydroxyapatite, tri-calcium phosphate, mono-calcium phosphate, calcium silicate, and bioactive glass. The advantageous properties and limitations of these materials are also discussed. In the end, future directions and proposals are given to improve the physical and mechanical properties of bioactive materials-based dental materials.

Fast self-curing α-tricalcium phosphate/β-dicalcium silicate composites beneficial for root canal sealing treatment

Objectives

α-tricalcium phosphate (α-TCP) and β-dicalcium silicate (β-C2S) have attracted much attention since these two types of self-curing Ca-phosphate and Ca-silicate are valuable biomaterials for bone defect or endodontic therapy. However, the injectable paste of their individual with high liquid/solid ratio is junior for root canal sealing due to very long self-setting time, low pH value and/or much volume shrinkage during paste-to-cement transformation.

Methods

Our studies evaluated the effect of biphasic ratio, liquid/solid ratio and pH condition of aqueous medium on setting time and mechanical strength of this biphasic composite cement, and also the hydroxyapatite re-mineralization potential and anti-microleakage level of the cements with different α-TCP/β-C2S ratio were explored in vitro. A control group free of paste filler was included in the extracted teeth model. Dentine re-mineralization and microleakage degree were observed by scanning electron microscopy and microCT reconstruction analysis.

Results

It indicated that the weak acidic solution with pH value of 6.0 may produce a significantly shorter initial setting time (from 90 min to less 20 min) and expected final setting time (<150 min) for the biphasic composite (2:1 or 1:2) in comparison with the pure β-C2S. Notably, the phasic composites exhibited limited microleakage and induced hydroxyapatite mineralization in the dentine tubules. These hydraulic pastes also produced strong alkaline feature and appreciable compressive resistance (12–18 MPa) after setting for a very short time stage. Moreover, a link between the addition of α-TCP leading to fast re-mineralization reaction was established.

Significance

Our findings suggest that the appreciable self-setting and physicochemical properties adaption to root canal sealability make α-TCP/β-C2S composites as preferential candidates for endodontic treatments.

An Insight into the Role of Marine Biopolymer Alginate in Endodontics: A Review

Alginate is a natural marine biopolymer that has been widely used in biomedical applications, but research on its use as an endodontic material is still sparse in the literature. This pioneer review aims to summarize the emerging roles of alginate and to outline its prospective applications as a core biomaterial in endodontics. Ten electronic databases and five textbooks were used to perform a search of English-language literature on the use of alginate in endodontics published between January 1980 and June 2022. The risk of bias (RoB) of each included study was assessed using the Office of Health Assessment and Translation (OHAT) tool. Subsequently, studies were categorized into three tiers to represent the overall risk. Qualitative analysis was performed, and the articles were sorted into different thematic categories. An initial search yielded a total of 1491 articles, but only 13 articles were chosen. For most domains, all the studies were rated with ‘probably low’ or ‘definitely low’ RoB, except for domains 2 and 6. All included studies fall in the Tier 1 category and were either in vitro, in vivo, or ex vivo. Four thematic categories were identified: endodontic regeneration, intracanal medicament, filing material, and chelating agent. Based on the available evidence, alginate has emerged as a cell carrier and scaffold in regenerative endodontics, a microcapsule delivery system for intracanal medicaments, a chelating agent reinforcing material, and a root canal sealer. More well-designed experiments and clinical trials are needed to warrant the promising advent of this hydrogel-based biomaterial.

PA-12-Zirconia-Alumina-Cenospheres 3D Printed Composites: Accelerated Ageing and Role of the Sterilisation Process for Physicochemical Properties

The aim of this study was to conduct artificial ageing tests on polymer-ceramic composites prepared from polyamide PA-12 polymer matrix for medical applications and three different variants of ceramic fillers: zirconia, alumina and cenospheres. Before ageing, the samples were subjected to ethyl oxide sterilization. The composite variants were prepared for 3D printing using the fused deposition modeling method. The control group consisted of unsterilized samples. Samples were subjected to artificial ageing in a high-pressure autoclave. Ageing conditions were calculated from the modified Hammerlich Arrhenius kinetic equation. Ageing was carried out in artificial saliva. After ageing the composites were subjected to mechanical (tensile strength, hardness, surface roughness) testing, chemical and structural (MS, FTIR) analysis, electron microscopy observations (SEM/EDS) and absorbability measurements.

Strategies of Bioceramics, Bioactive Glasses in Endodontics: Future Perspectives of Restorative Dentistry

Prevalently, there is a primary strategy to cure caries using restorative materials notably bioceramics. Existing synthetic materials stimulate natural tooth structure with acceptable interfacial bonding and esthetic and biomechanical qualities with better durability. Several bioceramics have been introduced and investigated for their potentialities as restorative materials. Biomineralization of tooth initiates repair and regeneration of natural dental tissue and reinstating the integrity of periodontium. In the evolution of bioceramics in the aspects of different essential composition for dental application, recent technology and modern strategies revolutionize the restorative dentistry. Bioglass is one among the important bioceramics as a restorative material, and by regulating the properties of the material, it is possible to construct improved formulation towards restoration. This article reviews the current revolution of endodontics, existing restorative materials, and technologies to be achieve for engineering materials with the better design.

Cenospheres-Reinforced PA-12 Composite: Preparation, Physicochemical Properties, and Soaking Tests

The main aim of this research was the preparation of a polymer–ceramic composite with PA-12 as the polymer matrix and modified aluminosilicate cenospheres (CSs) as the ceramic filler. The CSs were subjected to an early purification and cleaning process, which was also taken as a second objective. The CSs were surface modified by a two-step process: (1) etching in Piranha solution and (2) silanization in 3-aminopropyltriethoxysilane. The composite was made for 3D printing by FDM. Raw and modified CSs and a composite with PA-12 were subjected to the following tests: surface development including pores (BET), real density (HP), chemical composition and morphology (SEM/EDS, FTIR), grain analysis (PSD), phase composition (XRD), hardness (HV), and static tensile tests. The composites were subjected to soaking under simulated body fluid (SBF) conditions in artificial saliva for 14, 21, and 29 days. Compared to pure PA-12, PA-12_CS had generally better mechanical properties and was more resistant to SBF at elevated temperatures and soaking times. These results showed this material has potential for use in biomedical applications. These results also showed the necessity of developing a kinetic aging model for aging in different liquids to verify the true value of this material.

The First Step in Standardizing an Artificial Aging Protocol for Dental Composites—Evaluation of Basic Protocols

The clinical performance of a dental restoration is strongly influenced by the complex and dynamically-changing oral environment; however, no standard procedure exists to evaluate this lifetime. This research provides an in-depth analysis of the effect of different aging procedures on the flexural strength (FS), diametral tensile strength (DTS) and hardness (HV) of selected dental materials (Resin F, Flow-Art and Arkon). Material structure was evaluated by scanning electron microscopy. It was found that each aging protocol had some influence on the tested properties, with continual erosion and degradation being observed. Greater mechanical degradation was observed for Resin F (neat resin) after the applied aging protocols, suggesting that a resin matrix is more susceptible for degradation. The most aggressive aging protocol was Protocol 5: 0.1 M NaOH, seven days, 60 °C. Further studies on the effect of artificial aging on dental materials should include a study of the thermal and chemical factors. A standardized aging procedure is crucial for improving the resistance of dental resin composite to oral conditions and their clinical performance.

Sol-gel bioactive glass containing biomaterials for restorative dentistry: A review

OBJECTIVE

Bioactive glasses (BAGs) have been researched extensively for dentistry due to their favourable biocompatibility and hard tissue bonding ability. However, the specific application of BAGs produced through sol-gel synthesis in restorative dentistry has not been reviewed previously. This review provides a comprehensive account of the principles behind sol-gel derived BAGs and their investigation for dental tissue restoration materials.

METHODS

A search for in vitro and in vivo studies was performed using the databases Web of Science®, Medline®, Scopus® and Google Scholar®. Articles published over the past 20 years were selected and data on the BAG composition and morphology was extracted. Analysis of the effect of specific BAG additives on the properties of experimental dental materials was also performed.

RESULTS

A majority of BAG particles investigated were spheres ranging in size from 5 nm to ~650 µm. Sol-gel BAGs are mainly applied in the treatment of hypersensitive dentine and for pulp-dentine tissue engineering, while a handful have been used in target drug delivery. BAG fillers are promising additives that result in improved biological properties, antibacterial effects, hardness, acid buffering and remineralization. Unfortunately, some detrimental effects on optical properties have been observed with BAG addition. Additionally, in vivo data, investigations into radiopacity and standardization of test protocols are identified as areas for improvement and further studies.

SIGNIFICANCE

Future work should consider the pertinent issues raised in order to improve the quality of available data and expand knowledge in this area of dental biomaterials research and development.

Emergence of Nano-Dentistry as a Reality of Contemporary Dentistry

(1) Background. Nanotechnology offers significant alternative ways to solve scientific, medical, and human health issues. Dental biomaterials were improved by nanotechnology. It manufactures better materials or improves the existing ones and forms the basis of novel methods for disease diagnosis and prevention. Modern nanotechnology makes oral health care services more acceptable for patients. Nanotechnology is now important area of research, covering a broad range of applications in dentistry. (2) Methods. Relevant literature from Scopus published in English was selected using the keywords “nanoparticle” and “dentistry”. To the selected articles we applied the inclusion and exclusion criteria to choose the relevant ones. (3) Results. Based on the relevant articles, a literature review was prepared. This review provides an insight into the applications of nanotechnology in various branches of dentistry. We applied several regression models to fit number of papers versus time and chose the best one. We used it to construct the forecast and its 95%-confidence interval for the number of publications in 2022–2026. (4) Conclusions. It shows that a significant rise in papers is expected. This review familiarizes dentists with properties and benefits of nanomaterials and nanotechnology. Additionally, it can help scientists to consider the direction of their research and to plan prospective research projects.

Effects of Monomer Composition of Urethane Methacrylate Based Resins on the C=C Degree of Conversion, Residual Monomer Content and Mechanical Properties

(1) Background: This study investigated the influence of Bis-GMA, TEGDMA, UDMA, and two different polyethylene glycol (PEG)-containing, UDMO-based co-monomers on the Young’s modulus and flexural strength, degree of methacrylate C=C double bond conversion and residual monomer elution of experimental dental resins. (2) Methods: Urethane methacrylate-based monomer was synthesised via a radical chain growth polymerization mechanism using PEG in order to improve the mechanical properties. Dental resins were formulated using Bis-GMA, UDMA, or UDMO as base monomers combined with TEGDMA as a dilution monomer and DMAEM + CQ as the photo-initiator system. Degree of conversion (DC), mechanical properties, and residual monomer content of light-activated methacrylate resin formulations were evaluated and statistically analysed by ANOVA and a Tukey’s test. (3) Results: PEG-containing UDMO resins had lower Young’s modulus and elastic strength than UDMA-derived resin for all irradiation times. The highest DC (67,418%) was observed for the PEG-containing UDMO-based resin formulation when light cured for 40 s. For all samples, DC increased with the photo-polymerization time. The amount of residual monomer decreased after increasing the light-curing period from 20 to 40 s, resin with UDMO content 0.01 mol of PEG having the smallest amount of free eluted monomer. (4) Conclusions: A strong structure–property relationship exists in photo-cured dimethacrylate-based dental resins. The time and quantity of the photochemical initiation system can influence the physical–mechanical properties of the resins but also the monomers in their composition.

Evaluation of the Behavior of Two CAD/CAM Fiber-Reinforced Composite Dental Materials by Immersion Tests

Fiber-reinforced composites are used as restorative materials for prosthetic oral rehabilitation. Gastroesophageal reflux disease (GERD) is an accustomed affection with various oral manifestations. This study aimed to evaluate the behavior of two high-performance CAD/CAM milled reinforced composites (Trinia™, TriLor) in artificial saliva at different pH levels through immersion tests, and to determine if changes in mass or surface morphology at variable pH, specific for patients affected by GERD, appear. After investigating the elemental composition and surface morphology, the specimens were immersed in Carter Brugirard artificial saliva for 21 days at different pH values (5.7, 7.6, and varying the pH from 5.7 to 3). The values of the weighed masses during the immersion tests were statistically processed in terms of mean and standard deviation. Results suggested that irrespective of the medium pH, the two composites presented a similar mass variation in the range of -0.18 (±0.01)-1.82 (±0.02) mg after immersion, suggesting their stability when in contact with artificial saliva, an aspect which was also highlighted by scanning electron microscope (SEM) analysis performed on the immersed surfaces. Novel composite biomaterials can be a proper alternative for metal alloys used for prosthetic frameworks in patients suffering from GERD.

Five decades of the International Endodontic Journal: Bibliometric overview 1967-2020

AIM

The International Endodontic Journal (IEJ) has served as a platform for research and clinical practice in Endodontics since 1967. This study provides a bibliographic analysis and overview of the publications that have appeared in the IEJ from 1967 to 2020.

METHODOLOGY

A literature search was performed in Elsevier's Scopus database to locate all the publications of the International Endodontic Journal. Various bibliometric software packages including the open-source visualization software Gephi and Biblioshiny (version 2.0) were employed for data visualization and analysis.

RESULTS

A total of 3739 records with citation and bibliographic details were selected and retrieved to allow a bibliometric analysis to be performed. The bibliometric analysis indicates that the IEJ has grown both in terms of productivity and influence. Over time, the journal has been associated with an increase in the number of manuscripts published and the citations they have attracted, but with minor downward fluctuations in citations in the last few years. Bibliographic coupling of the IEJ articles revealed that the major research themes published in the journal include 'endodontics', 'root canal treatment', 'calcium hydroxide', 'apical periodontitis', 'mineral trioxide aggregate', 'microbiology', 'cyclic fatigue', 'cone-beam computed tomography' and 'micro-computed tomography'. Authors affiliated to institutions in the UK were the major contributors to the journal and were linked with other countries such as Brazil, USA and Malaysia. The largest number of publications were from the University of São Paulo, Brazil.

CONCLUSION

The IEJ is one of the leading journals in Endodontology and has been providing a platform for innovative research and clinical reports for more than 50 years. Publications have been associated with a wide range of authors, institutions and countries around the world.

An Evaluation of the Properties of Urethane Dimethacrylate-Based Dental Resins

Most of the dental materials available on the market are still based on traditional monomers such as bisphenol A-glycidyl methacrylate (Bis-GMA), urethane dimethacrylate (UDMA), triethyleneglycol dimethacrylate (TEGDMA), and ethoxylated bisphenol-A dimethacrylate (Bis-EMA). The interactions that arise in the monomer mixture and the characteristics of the resulting polymer network are the most important factors, which define the final properties of dental materials. The use of three different monomers in proper proportions may create a strong polymer matrix. In this paper, fourteen resin materials, based on urethane dimethacrylate with different co-monomers such as Bis-GMA or Bis-EMA, were evaluated. TEGDMA was used as the diluting monomer. The flexural strength (FS), diametral tensile strength (DTS), and hardness (HV) were determined. The impacts of material composition on the water absorption and dissolution were evaluated as well. The highest FS was 89.5 MPa, while the lowest was 69.7 MPa. The median DTS for the tested materials was found to range from 20 to 30 MPa. The hardness of the tested materials ranged from 14 to 16 HV. UDMA/TEGDMA matrices were characterized by the highest adsorption values. The overall results indicated that changes in the materials' properties are not strictly proportional to the material's compositional changes. The matrices showed good properties when the composite contained an equal mixture of Bis-GMA/Bis-EMA and UDMA or the content of the UDMA monomer was higher.