Navigating the practical-knowledge gap in deep margin elevation: A step towards a structured case selection - a review.

The deep margin elevation (DME) technique has gained popularity because of numerous supporting case reports. However, some clinicians are cautious regarding using this technique owing to the lack of clear case selection criteria for DME application. This review aimed to analyze case reports and a series of DME cases to determine pre-/post-operative evaluation methods that could be used to suggest a pre-operative case selection checklist for DME. An electronic database search was conducted in June 2021 and updated by June 2023 using selected terms from PubMed, Cochrane Library, Google Scholar, EBSCO, and Scopus. The search was limited to English-language publications and was not restricted to the date. The inclusion criteria were case reports/series addressing periodontal and restorative outcomes of DME. The search identified 217 articles, 76 of which were pertinent. However, only six case reports and one case series satisfied the inclusion criteria. None of the selected studies followed any reporting guidelines, which led to significant information gaps. While the reviewed studies reported favorable outcomes, standardized protocols for evaluating pre-/post-operative restorative and periodontal status were lacking. The post-operative follow-up period varied from 3 months to 6 years. Designing and implementing pre-/post-operative guidelines hold the potential for ensuring the safe application of the DME technique. This may enhance our understanding of the suitability and efficacy of such non-invasive technique in future clinical trials. Clinical significance: Handling deep cavities and preparing crowns are challenging. However, a lack of understanding of when to perform DME can lead to missed opportunities for conservative treatment, thereby a disservice to the patient. Provision of safe guidelines should be employed by clinicians until further evidence either supports or contradicts this treatment method.

Predictors of procedural errors in class II resin composite restorations using bitewing radiographs.

Objective: To identify the potential factors that induce procedural errors during posterior proximal resin composite restorations placed by dental students. Materials and Methods: This retrospective study evaluated 803 bitewing radiographs of posterior proximal resin composite restorations placed by dental students at Imam Abdulrahman bin Faisal University. Atypical radiographic signs of failure were screened, and different patient-, operator-, and clinical-related factors were recorded. Chi-square test was used to examine the relationship between procedural errors and recorded factors. Stepwise adjusted logistic regression model was performed to identify predictors of procedural errors. Results: The most observed errors were internal gaps at the bonding interface and internal voids. Molars had 0.39 the risk of internal voids (odds ratio [OR] = 0.39; confidence interval [CI] = 0.25-0.60; P = <0.0001), 0.41 the risk of sharp angle (OR = 0.41; CI = 0.24-0.68; P = <0.001), and 0.57 the risk of open contact (OR = 0.57; CI = 0.34-0.97; P = 0.04) compared to premolars. Those who were >40 years of age had 1.79 the risk of overhang compared to younger patients (OR = 1.79; CI = 1.04-3.11; P = <0.04). First molars and premolars had 0.64 the risk of overhang compared to second molars and premolars (OR = 0.64; CI = 0.41-1.00; P = 0.04). Junior students had 1.97 the risk of internal gap compared to their senior counterparts (OR = 1.97; CI = 1.20-3.21; P = 0.008). Mesial restorations had 0.38 the risk of external gap compared to mesio-occluso-distal (MOD) restorations (OR = 0.38; CI = 0.19-0.78; P = 0.003). Restorations with a margin coronal to the cemento-enamel junction (CEJ) had 0.44 the risk of external gap compared to those restorations with a margin apical to the CEJ (OR = 0.44; CI = 0.29-0.66; P = <0.0001). Conclusion: Our findings suggested a higher incidence of procedural errors in restoring premolars and MOD cavity preparations. Therefore, it is crucial to enhance the comprehensiveness of laboratory training and expose students to diverse clinical scenarios and various techniques.

The demineralization resistance and mechanical assessments of different bioactive restorative materials for primary and permanent teeth: an in vitro study.

OBJECTIVES: This article examines the efficacy of two bioactive dental composites in preventing demineralization while preserving their mechanical and physical properties. MATERIALS AND METHODS: The study compares Beautifil Kids and Predicta® Bioactive Bulk-Fill (Predicta) composites with conventional dental composite. Flexural strength and elastic modulus were evaluated using a universal testing machine. A pH-cycling model assessed the composites' ability to prevent dentin demineralization. Color stability and surface roughness were measured using a spectrophotometer and non-contact profilometer, respectively, before and after pH-cycling, brushing simulation, and thermocycling aging. RESULTS: Beautifil Kids exhibited the highest flexural strength and elastic modulus among the materials (p < 0.05). Predicta demonstrated the highest increase in dentin surface microhardness following the pH-cycling model (p < 0.05). All groups showed clinically significant color changes after pH-cycling, with no significant differences between them (p > 0.05). Predicta exhibited greater color change after brushing and increased surface roughness after thermocycling aging (p < 0.05). While Beautifil Kids had higher surface roughness after pH-cycling (p < 0.05). DISCUSSION/CONCLUSION: Bioactive restorative materials with ion-releasing properties demonstrate excellent resistance to demineralization while maintaining mechanical and physical properties comparable to the control group.

Multifunctional Dental Adhesives Formulated with Silane-Coated Magnetic Fe3O4@m-SiO2 Core-Shell Particles to Counteract Adhesive Interfacial Breakdown.

The process of bonding to dentin is complex and dynamic, greatly impacting the longevity of dental restorations. The tooth/dental material interface is degraded by bacterial acids, matrix metalloproteinases (MMPs), and hydrolysis. As a result, bonded dental restorations face reduced longevity due to adhesive interfacial breakdown, leading to leakage, tooth pain, recurrent caries, and costly restoration replacements. To address this issue, we synthesized and characterized a multifunctional magnetic platform, CHX@SiQuac@Fe3O4@m-SiO2, to provide several beneficial functions. The platform comprises Fe3O4 microparticles and chlorhexidine (CHX) encapsulated within mesoporous silica, which was silanized by an antibacterial quaternary ammonium silane (SiQuac). This platform simultaneously targets bacterial inhibition, stability of the hybrid layer, and enhanced filler infiltration by magnetic motion. Comprehensive experiments include X-ray diffraction, FT-IR, VSM, EDS, N2 adsorption-desorption (BET), transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, and UV-vis spectroscopy. Then, CHX@SiQuac@Fe3O4@m-SiO2 was incorporated into an experimental adhesive resin for dental bonding restorations, followed by immediate and long-term antibacterial assessment, cytotoxicity evaluation, and mechanical and bonding performance. The results confirmed the multifunctional nature of CHX@SiQuac@Fe3O4@m-SiO2. This work outlined a roadmap for (1) designing and tuning an adhesive formulation containing the new platform CHX@SiQuac@Fe3O4@m-SiO2; (2) assessing microtensile bond strength to dentin using a clinically relevant model of simulated hydrostatic pulpal pressure; and (3) investigating the antibacterial outcome performance of the particles when embedded into the formulated adhesives over time. The results showed that at 4 wt % of CHX@SiQuac@Fe3O4@m-SiO2-doped adhesive under the guided magnetic field, the bond strength increased by 28%. CHX@SiQuac@Fe3O4@m-SiO2 enhanced dentin adhesion in the magnetic guide bonding process without altering adhesive properties or causing cytotoxicity. This finding presents a promising method for strengthening the tooth/dental material interface's stability and extending the bonded restorations' lifespan.

The Effect of Salbutamol and Budesonide Pediatric Doses on Dental Enamel and Packable and Flowable Composites: Microhardness, Surface Roughness and Color.

OBJECTIVE: To assess and compare the effects of two pediatric anti-asthmatic medication doses on the microhardness of enamel and microhardness, surface roughness and color of restorative materials. METHODS: Human enamel samples and packable and flowable composite restorations were used. The samples were exposed to Salbutamol (0.6 mL/6 mL saline) and Budesonide (2 mL/2 mL saline) via a custom-made chamber connected to a nebulizer. Medication administration was conducted for 10 days. The samples were brushed with an electronic brush in a continuous and circular mode for 10 s after 10 min of medication administration. Assessments of microhardness, surface roughness and color were carried out at three different time intervals: baseline (T0), 5 days (T1) and 10 days (T2). One-way analysis of variance (ANOVA), a two-sample t-test and a Bonferroni multiple comparison test were used to analyze the data and compare between the groups. RESULTS: Both medications significantly (p < 0.05) decreased the microhardness of the enamel and composite samples after 10 days. Both medications lowered the surface roughness of both types of composite with a greater effect observed after 10 days of Budesonide administration (p < 0.05). Both medications had comparable detectable color change on both types of composite with a greater effect observed after 10 days of Budesonide administration (p < 0.05). CONCLUSION: Salbutamol and Budesonide significantly decreased microhardness in the enamel samples. Both medications affected the properties of packable and flowable composites. The packable composite showed more resistance to microhardness changes. Both medications showed a clinically detectable change in the color of packable and flowable composites.

Novel Bioactive Nanocomposites Containing Calcium Fluoride and Calcium Phosphate with Antibacterial and Low-Shrinkage-Stress Capabilities to Inhibit Dental Caries.

OBJECTIVES: Composites are commonly used for tooth restorations, but recurrent caries often lead to restoration failures due to polymerization shrinkage-stress-induced marginal leakage. The aims of this research were to: (1) develop novel low-shrinkage-stress (L.S.S.) nanocomposites containing dimethylaminododecyl methacrylate (DMADDM) with nanoparticles of calcium fluoride (nCaF2) or amorphous calcium phosphate (NACP) for remineralization; (2) investigate antibacterial and cytocompatibility properties. METHODS: Nanocomposites were made by mixing triethylene glycol divinylbenzyl ether with urethane dimethacrylate containing 3% DMADDM, 20% nCaF2, and 20% NACP. Flexural strength, elastic modulus, antibacterial properties against Streptococcus mutans biofilms, and cytotoxicity against human gingival fibroblasts and dental pulp stem cells were tested. RESULTS: Nanocomposites with DMADDM and nCaF2 or NACP had flexural strengths matching commercial composite control without bioactivity. The new nanocomposite provided potent antibacterial properties, reducing biofilm CFU by 6 logs, and reducing lactic acid synthesis and metabolic function of biofilms by 90%, compared to controls (p < 0.05). The new nanocomposites produced excellent cell viability matching commercial control (p > 0.05). CONCLUSIONS: Bioactive L.S.S. antibacterial nanocomposites with nCaF2 and NACP had excellent bioactivity without compromising mechanical and cytocompatible properties. The new nanocomposites are promising for a wide range of dental restorations by improving marginal integrity by reducing shrinkage stress, defending tooth structures, and minimizing cariogenic biofilms.

Effect of eucalyptus oil on Streptococcus mutans and Enterococcus faecalis growth.

OBJECTIVES: There is a significant apprehension in medicine and dentistry concerning the emergence of antibiotic-resistant pathogens, as it composes a significant threat to global health, particularly oral health. The growing concern that oral pathogens may develop resistance against standard preventive measures raises the need for alternative measures to prevent these pathogens' growth without inducing microbial resistance. Therefore, this study aims to assess the antibacterial properties of eucalyptus oil (EO) against two main oral disease pathogens, Streptococcus mutans, and Enterococci faecalis. METHODS: S. mutans and E. faecalis biofilms were initiated using brain-heart infusion (BHI) broth supplemented with 2% sucrose with and without diluted EO. After 24 h of biofilm formation, total absorbance was measured via spectrophotometer; then, the biofilm was fixed, stained with crystal violet dye, and measured at 490 nm. An Independent t-test was used to compare the outcomes. RESULTS: Diluted EO revealed significant total absorbance reduction against S. mutans and E. faecalis compared to the control (p ≤ 0.001). For the biofilm measurement, S. mutans and E. faecalis biofilms were reduced by around 60- and 30-fold, respectively, compared to the group with no EO (p ≤ 0.001). CONCLUSION: Based on this study's results, using EO as an organic compound could be considered an adjunctive tool in preventing the growth of oral pathogens causing dental caries and endodontic infection.

Recurrent caries models to assess dental restorations: A scoping review.

OBJECTIVES: To review the literature on recurrent caries models used to evaluate restorative materials, compare reported methodology and parameters, and devise specific recommendations to be considered in future investigations. DATA: The following were extracted: study design, sample characteristics, source of teeth, name of restorations compared including controls, recurrent caries model type, type of demineralizing and remineralizing solutions, type of biofilm used, methods to detect recurrent caries. SOURCES: Literature searches were performed in OVID Medline, EMBASE, SCOPUS, and Cochrane Library. STUDY SELECTION: For a study to be included, it had to examine dental materials for tooth restoration purposes only with a valid control group and evaluate restorative dental materials regardless of the form of the teeth caries model used or nature of the tooth structure used. A total of 91 studies were included. Most of the studies presented were in vitro. Human teeth were the main source of specimens utilized. Around 88% of the studies used specimens without an artificial gap, and 44% used a chemical model. S. mutans was the main bacterial species used in microbial caries models. CONCLUSION: The findings of this review provided an insight into the performance of available dental materials assessed using different recurrent caries models, yet this review cannot be used as a guideline for material selection. Selecting the appropriate restorative material relies on several patient-related factors such as microbiota, occlusion, and diet that are not comprehensively taken into consideration in recurrent caries models and thus hinder reliable comparison. CLINICAL SIGNIFICANCE: Due to the heterogenicity of variables among studies on the performance of dental restorative materials, this scoping review aimed to provide insights for dental researchers concerning the available recurrent caries models, testing methods used, and aspects of comparison between these materials including their characteristics and limitations.

Inorganic Compounds as Remineralizing Fillers in Dental Restorative Materials: Narrative Review.

Secondary caries is one of the leading causes of resin-based dental restoration failure. It is initiated at the interface of an existing restoration and the restored tooth surface. It is mainly caused by an imbalance between two processes of mineral loss (demineralization) and mineral gain (remineralization). A plethora of evidence has explored incorporating several bioactive compounds into resin-based materials to prevent bacterial biofilm attachment and the onset of the disease. In this review, the most recent advances in the design of remineralizing compounds and their functionalization to different resin-based materials' formulations were overviewed. Inorganic compounds, such as nano-sized amorphous calcium phosphate (NACP), calcium fluoride (CaF2), bioactive glass (BAG), hydroxyapatite (HA), fluorapatite (FA), and boron nitride (BN), displayed promising results concerning remineralization, and direct and indirect impact on biofilm growth. The effects of these compounds varied based on these compounds' structure, the incorporated amount or percentage, and the intended clinical application. The remineralizing effects were presented as direct effects, such as an increase in the mineral content of the dental tissue, or indirect effects, such as an increase in the pH around the material. In some of the reported investigations, inorganic remineralizing compounds were combined with other bioactive agents, such as quaternary ammonium compounds (QACs), to maximize the remineralization outcomes and the antibacterial action against the cariogenic biofilms. The reviewed literature was mainly based on laboratory studies, highlighting the need to shift more toward testing the performance of these remineralizing compounds in clinical settings.

Three-dimensional (3D) printing in dental practice: Applications, areas of interest, and level of evidence.

OBJECTIVES: The aim of this review to overview three-dimensional (3D) printing technologies available for different dental disciplines, considering the applicability of such technologies and materials development. MATERIALS AND METHODS: Source Arksey and O'Malley's five stages framework using PubMed, EMBASE, and Scopus (Elsevier) databases managed this review. Papers focusing on 3D printing in dentistry and written in English were screened. Scientific productivity by the number of publications, areas of interest, and the focus of the investigations in each dental discipline were extracted. RESULTS: Nine hundred thirty-four studies using 3D printing in dentistry were assessed. Limited clinical trials were observed, especially in Restorative, endodontics, and pediatric dentistry. Laboratory or animal studies are not reliable for clinical success, suggesting that clinical trials are a good approach to validate the new methods' outcomes and ensure that the benefits outweigh the risk. The most common application for 3D printing technologies is to facilitate conventional dental procedures. CONCLUSIONS: The constantly improving quality of 3D printing applications has contributed to increasing the popularity of these technologies in dentistry; however, long-term clinical studies are necessary to assist in defining standards and endorsing the safe application of 3D printing in dental practice. CLINICAL RELEVANCE: The recent progress in 3D materials has improved dental practice capabilities over the last decade. Understanding the current status of 3D printing in dentistry is essential to facilitate translating its applications from laboratory to the clinical setting.

Benzyldimethyldodecyl Ammonium Chloride Doped Dental Adhesive: Impact on Core's Properties, Biosafety, and Antibacterial/Bonding Performance after Aging.

Current dental adhesives lack antibacterial properties. This study aimed to explore the effect of incorporating benzyldimethyldodecyl ammonium chloride (BDMDAC) on the degree of conversion, contact angle, ultimate tensile strength (UTS), microtensile bond strength (µTBS), cytotoxicity, antibacterial and bonding performance after artificial aging. A dental adhesive was doped with BDMDAC in the concentration range of 1-5 wt.%. For antibacterial assays, the BDMDAC compound was subject to planktonic cells of Streptococcus mutans. Then, after incorporation into the dental adhesive, an S. mutans biofilm model was used to grow 48 h-mature biofilms. The biofilms grown over the formulated materials were assessed by colony-forming unit (CFU) counting assay and fluorescence microscopy staining. In addition, the cytotoxicity was evaluated. Samples were subjected to 10,000 thermal cycles for aging and evaluated by UTS, µTBS, and CFU. Incorporating BDMDAC did not increase the cytotoxicity or change the physical properties when the mass fraction of the BDMDAC was 1-5 wt.%. The UTS of BDMDAC-doped adhesives was not impaired immediately or over time. A significant bacterial reduction was obtained for the mass fraction of the BDMDAC greater than 3 wt.%. However, the BDMDAC-doped adhesives did not offer an antibacterial effect after artificial aging. The overall results indicate that the BDMDAC strategy has the potential to control of microbial growth of cariogenic planktonic cells and biofilms. However, other new technological approaches are needed to overcome the deleterious effect of BDMDAC release over time such as those based on the principle of drug delivery systems whereby the BDMDAC is transported on microparticles or core shells, providing tangible benefits to oral health over time.

Novel rechargeable nano-calcium phosphate and nano-calcium fluoride resin cements.

OBJECTIVE: In most clinical circumstances, secondary caries at the margin of fixed dental restorations leads to restoration failure and replacement. Accordingly, the objectives of this study were to: (1) develop a novel rechargeable nano-calcium phosphate (NACP) and nano-calcium fluoride (nCaF2) resin-based cement; and (2) investigate their mechanical properties and calcium (Ca), phosphate (P), and fluoride (F) ion release, recharge, and re-release for the first time. METHODS: The cement matrix consisted of pyromellitic glycerol dimethacrylate (PMGDM), ethoxylated bisphenol-A-dimethacrylate (EBPADMA) was denoted PEHB. Four cements were fabricated: (1) PEHB+0%NACP+0%nCaF2 (experimental control); (2) PEHB+25%NACP+0%nCaF2, (3) PEHB+0%NACP+25%nCaF2; (4) PEHB+12.5%NACP+12.5% nCaF2. RelyX luting cement was used as a commercial control. Mechanical properties and long-term Ca, P, and F ion release, recharge, and re-release were evaluated. RESULTS: Adding 25% NACP, 25% nCaF2 and adding both 12.5% NACP and 12.5% nCaF2 to the cement matrix presented a significantly higher shear bond strength, flexural strength compared to the commercial control (p < 0.05) with a comparable outcome with no significant different (p > 0.05) compared to experimental control. The film thickness results of all cement groups met the ISO requirement (<50 µm). The resin cement group with both 12.5% NACP and 12.5% nCaF2 successfully released Ca, P, and F ions at 3.1 ± 0.01, 1.1 ± 0.05, and 0.51±0.01 mmol/L respectively. Moreover, it showed the ability to re-release Ca, P, and F ions at 0.62±0.01, 0.12±0.01, and 0.42±0.01 mmol/L respectively. CONCLUSIONS: The resin cement group with both 12.5% NACP and 12.5% nCaF2 demonstrated the advantages of both types of bio-interactive fillers as it could release a higher level of ions than the resin cement with 25%nCAF2 and exhibited a better rechargeability compared to the resin cement with 25%NACP. CLINICAL SIGNIFICANCE: The ability of this novel resin-based cement to release, recharge, and re-release Ca, P, and F ions could be one of the keys to lengthening the survivability of fixed dental restorations. These features could help to reduce the onset of secondary caries by enhancing the remineralization and preventing the demineralization of tooth structures.

Novel antibacterial low-shrinkage-stress resin-based cement.

OBJECTIVE: A low-shrinkage-stress resin-based cement with antibacterial properties could be beneficial to create a cement with lower stress at the tooth-restoration interface, which could help to enhance the longevity of the fixed dental restoration by reducing microleakage and recurrent caries. To date, there has been no report on the development of a low-shrinkage-stress and bio-interactive cement. Therefore, the objectives of this study were to develop a novel low-shrinkage-stress resin-based cement containing dimethylaminohexadecyl methacrylate (DMAHDM) and investigate the mechanical and antibacterial properties for the first time. METHODS: The monomers urethane dimethacrylate (UDMA) and triethylene glycol divinylbenzyl ether (TEG-DVBE) were combined and denoted as UV resin. Three cements were fabricated: (1) UV+ 0%DMAHDM (experimental control); (2) UV+ 3%DMAHDM, (3) UV+ %5DMAHDM. RelyX Ultimate cement was used as commercial control. Mechanical properties and Streptococcus mutans (S. mutans) biofilms growth on cement were evaluated. RESULTS: The novel bio-interactive cement demonstrated excellent antibacterial and mechanical properties. Compared to commercial and experimental controls, adding DMAHDM into the UV cement significantly reduced colony forming unit (CFU) counts by approximately 7 orders of magnitude, metabolic activities from 0.29 ± 0.03 A540/cm2 to 0.01 ± 0.01 A540/cm2, and lactic acid production from 22.3 ± 0.74 mmol/L to 1.2 ± 0.27 mmol/L (n = 6) (p < 0.05). The low-shrinkage-stress cement demonstrated a high degree of conversion of around 70 %, while reducing the shrinkage stress by approximately 60%, compared to a commercial control (p < 0.05). CONCLUSIONS: The new antibacterial low-shrinkage-stress resin-based cement provides strong antibacterial action and maintains excellent mechanical properties with reduced polymerization shrinkage stress. CLINICAL SIGNIFICANCE: A low-shrinkage-stress resin-based cement containing DMAHDM was developed with potent antibacterial effects and promising mechanical properties. This cement may potentially enhance the longevity of fixed dental restoration such as a dental crown, inlay, onlay, and veneers through its excellent mechanical properties, low shrinkage stress, and strong antibacterial properties.

Low-Shrinkage Resin Matrices in Restorative Dentistry-Narrative Review.

Dimethacrylate-based resin composites restorations have become widely-used intraoral materials in daily dental practice. The increasing use of composites has greatly enhanced modern preventive and conservative dentistry. They have many superior features, especially esthetic properties, bondability, and elimination of mercury and galvanic currents. However, polymeric materials are highly susceptible to polymerization shrinkage and stresses that lead to microleakage, biofilm formation, secondary caries, and restoration loss. Several techniques have been investigated to minimize the side effects of these shrinkage stresses. The primary approach is through fabrications and modification of the resin matrices. Therefore, this review article focuses on the methods for testing the shrinkage, as well as formulations of resinous matrices available to reduce polymerization shrinkage and its associated stress. Furthermore, this article reviews recent cutting-edge developments on bioactive low-shrinkage-stress nanocomposites to effectively inhibit the growth and activities of cariogenic pathogens and enhance the remineralization process.

In Vitro Analysis of the Fatigue Resistance of Four Single File Canal Preparation Instruments.

Instrument separation during root canal therapy is inevitable in endodontics with several unfavorable clinical consequences. Therefore, examining the cyclic flexural fatigue resistance of commonly used rotary endodontic files is crucial. This study aimed to determine the cyclic flexural fatigue resistance of four nickel-titanium (NiTi) rotary files used as a single canal preparation technique: WaveOne, Reciproc, Protaper F2, and Unicone medium instruments. According to the manufacturer's instructions, each file was rotated freely within a 1.3 mm deep and 1.3 mm wide V-shaped groove in a stainless-steel block with a 40° and 5 mm radius of curvature. Cyclic fatigue resistance was compared between the NiTi files by verifying the time needed to crack. The data were analyzed using one-way analysis of variance (ANOVA) followed by Scheffé post hoc with a significant level set at p < 0.05. Our results demonstrated that the WaveOne instrument had the highest cyclic flexural fatigue resistance among the tested groups (p ≤ 0.05), while Unicone had the lowest cyclic flexural fatigue resistance. This study concluded that WaveOne size 25/0.08 could illustrate a superior cyclic flexural fatigue resistance when instrumenting root canals with the lowest possibility to cause instrument separation.

Minimally-invasive dentistry via dual-function novel bioactive low-shrinkage-stress flowable nanocomposites.

The objectives of this in vitro study were to develop a novel low-shrinkage-stress flowable nanocomposite with antibacterial properties through the incorporation of dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP), and investigate the mechanical and oral biofilm properties, to be used in minimally-invasive techniques. METHODS: The light-cured low-shrinkage-stress flowable resin was formulated by mixing urethane dimethacrylate (UDMA) and triethylene glycol divinylbenzyl ether (TEG-DVBE) at a 1:1 mass ratio. Different mass fractions of glass, and either 5% DMAHDM or 20%NACP or both were incorporated. Paste flowability, ultimate micro tensile strength and surface roughness were evaluated. The antibacterial response of DMAHDM resin was assessed by using biofilms of human saliva-derived microcosm model. Virtuoso flowable composite was used as a control. RESULTS: (45% resin+5% DMAHDM+20% NACP+30% glass) formula yielded the needed outcomes. It had flow rate within the range of ISO requirement. The micro tensile strength was (39.1 ± 4.3) MPa, similar to (40.1 ± 4.0) MPa for commercial control (p > 0.05). The surface roughness values of the novel composite (0.079 ± 0.01) µm similar to commercial composite (0.09 ± 0.02) µm (p > 0.05). Salivary microcosm biofilm colony forming unit values were reduced by 5-6 logs (p < 0.05). Biofilm metabolic activity was also substantially reduced, compared to control composite (p < 0.05). SIGNIFICANCE: The novel bioactive flowable nanocomposite achieved strong antibacterial activities without compromising the mechanical properties. It is promising to be used as pit and fissure sealants, and as fillings in conservative cavities to inhibit recurrent caries and increase restoration longevity.

Prospects on Tuning Bioactive and Antimicrobial Denture Base Resin Materials: A Narrative Review.

Denture base resin (DBR) materials are used in dentistry in constructing removable dentures and implant-supported prostheses. A plethora of evidence has demonstrated that DBR materials are associated with a high risk of denture stomatitis, a clinical complication where the soft oral tissues underneath the resin-based material are inflamed. The prevalence of denture stomatitis among denture wearers is high worldwide. Plaque accumulation and the infiltration of oral microbes into DBRs are among the main risk factors for denture stomatitis. The attachment of fungal species, mainly Candida albicans, to DBRs can irritate the underneath soft tissues, leading to the onset of the disease. As a result, several attempts were achieved to functionalize antimicrobial compounds and particles into DBRs to prevent microbial attachment. This review article explored the advanced approaches in designing bioactive and antimicrobial DBR materials. It was reported that using monomer mixtures, quaternary ammonium compounds (QACs), and organic and inorganic particles can suppress the growth of denture stomatitis-related pathogens. This paper also highlighted the importance of characterizing bioactive DBRs to be mechanically and physically sustainable. Future directions may implement a clinical translational model to attempt these materials inside the oral cavity.

Magnetic-Responsive Photosensitizer Nanoplatform for Optimized Inactivation of Dental Caries-Related Biofilms: Technology Development and Proof of Principle.

Conventional antibiotic therapies for biofilm-trigged oral diseases are becoming less efficient due to the emergence of antibiotic-resistant bacterial strains. Antimicrobial photodynamic therapy (aPDT) is hampered by restricted access to bacterial communities embedded within the dense extracellular matrix of mature biofilms. Herein, a versatile photosensitizer nanoplatform (named MagTBO) was designed to overcome this obstacle by integrating toluidine-blue ortho (TBO) photosensitizer and superparamagnetic iron oxide nanoparticles (SPIONs) via a microemulsion method. In this study, we reported the preparation, characterization, and application of MagTBO for aPDT. In the presence of an external magnetic field, the MagTBO microemulsion can be driven and penetrate deep sites inside the biofilms, resulting in an improved photodynamic disinfection effect compared to using TBO alone. Besides, the obtained MagTBO microemulsions revealed excellent water solubility and stability over time, enhanced the aPDT performance against S. mutans and saliva-derived multispecies biofilms, and improved the TBO's biocompatibility. Such results demonstrate a proof-of-principle for using microemulsion as a delivery vehicle and magnetic field as a navigation approach to intensify the antibacterial action of currently available photosensitizers, leading to efficient modulation of pathogenic oral biofilms.

Antibacterial Activities of Methanol and Aqueous Extracts of Salvadora persica against Streptococcus mutans Biofilms: An In Vitro Study.

The use of herbal products in oral hygiene care has a long history, and their use is popular today. A tree stick, named Salvadora persica (S. persica), is commonly used to remove dental plaque and clean teeth in many countries. In addition, extracts of S. persica can be used as a mouthwash, as they demonstrate antimicrobial properties. This study aimed to investigate the antibacterial effect of S. persica methanol and aqueous extracts against Streptococcus mutans (S. mutans) biofilm. A S. mutans biofilm formation assay was conducted using different concentrations of S. persica methanol or water extracts in tryptic soy broth (TSB) supplemented with 1% sucrose. The biofilm was stained with crystal violet dye, and the absorbance was assessed to examine biofilm formation. One-way analysis of variance (ANOVA) and Tukey tests were used to analyze the results. The S. persica methanol extract displayed a significant inhibition (p ≤ 0.001) against the S. mutans biofilm. The 10 mg/mL concentration of the S. persica methanol extract was determined as the minimum biofilm inhibitory concentration (MBIC). The used methanol concentration, mixed with TSB supplemented with 1% sucrose and without the S. persica extract, did not inhibit the S. mutans biofilm. The S. persica aqueous extract did not demonstrate any biofilm inhibition at any concentration (p ≥ 0.05). The findings of this study suggest the potential of using S. persica methanol extract as a mouthwash or adjunctive to oral hygiene tools.