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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.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.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 AThe new antibacterial low-shrinkage-stress resin-based cement provides strong antibacterial action and maintains excellent mechanical properties with reduced polymerization shrinkage stress.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.

Composite restorations with calcium fluoride nanoparticles (nCaFThree nCaFBT and BTM nCaFNovel nCaF

Recurrent caries is a primary reason for restoration failure caused by biofilm acids. The objectives of this study were to: (1) develop a novel multifunctional composite with antibacterial function and calcium (Ca) and phosphate (P) ion release, and (2) investigate the effects on enamel demineralization and hardness at the margins under biofilms.Dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP) were incorporated into composite. Four groups were tested: (1) Commercial control (Heliomolar), (2) Experimental control (0% DMAHDM + 0% NACP), (3) antibacterial group (3% DMAHDM + 0% NACP), (D) antibacterial and remineralizing group (3% DMAHDM + 30% NACP). Mechanical properties and Ca and P ion release were measured. Colony-forming units (CFU), lactic acid and polysaccharide of Streptococcus mutans (S. mutans) biofilms were evaluated. Demineralization of bovine enamel with restorations was induced via S. mutans, and enamel hardness was measured. Data were analyzed via one-way and two-way analyses of variance and Tukey's multiple comparison tests.Adding DMAHDM and NACP into composite did not compromise the mechanical properties (P0.05). Ca and P ion release of 3% DMAHDM + 30% NACP was increased at cariogenic low pH. Biofilm lactic acid and polysaccharides were greatly decreased via DMAHDM, and CFU was reduced by 4 logs (P0.05). Under biofilm acids, enamel hardness at the margins was decreased to about 0.5 GPa for control; it was about 1 GPa for antibacterial group, and 1.3 GPa for antibacterial and remineralizing group (P0.05).The novel 3% DMAHDM + 30% NACP composite had strong antibacterial effects. It substantially reduced enamel demineralization adjacent to restorations under biofilm acid attacks, yielding enamel hardness that was 2-fold greater than that of control composites. The novel multifunctional composite is promising to inhibit recurrent caries.

Objective Pit and fissure sealants with antibacterial and remineralization properties have broad application prospects in caries prevention. The objectives of this study were to: (1) develop a novel pit and fissure sealant containing CaF2 nanoparticles (nCaF2) and dimethylaminohexadecyl methacrylate (DMAHDM); and (2) investigate the effects of nCaF2 and DMAHDM on biofilm response and fluoride (F) ion release for the first time. Methods Helioseal F was used as a control. Bioactive sealants were formulated with DMAHDM and nCaF2. Flow properties, enamel shear bond strength, hardness and F ion releases were measured. Streptococcus mutans (S. mutans) biofilms were grown on sealants. Biofilm metabolic activity, lactic acid production, colony-forming units (CFU), and pH of biofilm culture medium were measured. Results Adding 5% DMAHDM and 20% nCaF2 did not reduce the paste flow and enamel bond strength, compared to control (p Significance The new bioactive pit and fissure sealant with nCaF2 and DMAHDM achieved high fluoride release and strong antibacterial performance. This novel fluoride-releasing and antibacterial sealant is promising to inhibit caries and promote the remineralizaton of enamel and dentin.

Millions of people worldwide suffer from a toothache due to tooth cavity, and often permanent tooth loss. Dental caries, also known as tooth decay, is a biofilm-dependent infectious disease that damages teeth by minerals loss and presents a high incidence of clinical restorative polymeric fillings (tooth colored fillings). Until now, restorative polymeric fillings present no bioactivity. The complexity of oral biofilms contributes to the difficulty in developing effective novel dental materials. Nanotechnology has been explored in the development of bioactive dental materials to reduce or modulate the activities of caries-related bacteria. Nano-structured platforms based on calcium phosphate and metallic particles have advanced to impart an anti-caries potential to restorative materials. The bioactivity of these platforms induces prevention of mineral loss of the hard tooth structure and antibacterial activities against carries-related pathogens. It has been suggested that this bioactivity could minimize the incidence of caries around restorations (CARS) and increase the longevity of such filling materials. The last few years witnessed growing numbers of studies on the preparation evaluations of these novel materials. Herein, the caries disease process and the role of pathogenic caries-related biofilm, the increasing incidence of CARS, and the recent efforts employed for incorporation of bioactive nanoparticles in restorative polymer materials as useful strategies for prevention and management of caries-related-bacteria are discussed. We highlight the status of the most advanced and widely explored interaction of nanoparticle-based platforms and calcium phosphate compounds with an eye toward translating the potential of these approaches to the dental clinical reality., Graphical abstract Image 1, Highlights • Current progress and future applications of functional nanoparticles and remineralizing compounds incorporated in dental direct restorative materials. • Overview of the antibacterial and remineralizing mechanisms presenting direct and indirect implications on the tooth mineral loss. • These investigations, although in the initial phase of evidence are necessary and their results are encouraging and open the doors to future clinical studies that will allow the therapeutic value of nanotechnology-based restorative materials to be established.

Objective Secondary caries and micro-cracks are the main limiting factors for dentin bond durability. The objectives of this study were to develop a self-healing adhesive containing dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP), and investigate the effects of water-aging for 12 months on self-healing, dentin bonding, and antibacterial properties for the first time. Methods Microcapsules were synthesized with poly (urea-formaldehyde) (PUF) shells containing triethylene glycol dimethacrylate (TEGDMA) and N,N -dihydroxyethyl- p -toluidine (DHEPT). The adhesive contained 7.5% microcapsules, 10% DMAHDM, and 20% NACP (all mass). Specimens were water-aged at 37 °C for 1 day to 12 months. Dentin bond strength was measured using extracted human teeth. A single-edge-V-notched-beam (SEVNB) method was used to measure fracture toughness K IC and self-healing efficiency. A dental plaque microcosm biofilm model was used with human saliva as inoculum. Results The microcapsules + DMAHDM + NACP group showed no decline in dentin bond strength after water-aging for 12 months, which was significantly higher than that of other groups without DMAHDM ( p IC was obtained even after 12 months of water immersion, indicating that the self-healing ability was not lost in water-aging ( p > 0.1). The bacteria-killing ability of this adhesive did not decline from 1 day to 12 months ( p > 0.1), with biofilm CFU reduction by 3–4 orders of magnitude after the resin was water-aged for 12 months, compared to control resin. Significance This novel adhesive with triple merits of self-healing, antibacterial and remineralization functions showed an excellent long-term durability in water-aging for 12 months. This multifunctional adhesive has the potential for dental applications to heal cracks, inhibit bacteria, provide ions for remineralization, and increase the restoration longevity.

Bulk fracture and secondary caries are the two main problems causing failures and shortening the lifetime of dental resinous restorations. This article reviews recent research on self-healing dental and biomedical materials. This includes the development of self-healing dental resin composites and adhesives, combining self-healing with calcium phosphate nanoparticles in the resins for tooth lesion remineralization, and adding antibacterial monomer into self-healing resins to suppress oral biofilm grows and acid production. Furthermore, since the oral environment experiences saliva and drinks, this paper also reviews research on the self-healing of dental resins while being submerged in an aqueous environment, and the effect of long-term water-aging time from 1 day to 6 months on the self-healing capability. The new class of materials have demonstrated excellent self-healing efficacy in various material systems including bonding agents, composites and cements. They could heal cracks, regain load-bearing ability, inhibit oral pathogens, reduce or eliminate biofilm acids, raise biofilm pH to protect the teeth, and regenerate lost tooth minerals. Furthermore, their effects were indicated to be durable and long-lasting. While most of the recent publications on self-healing dental resins are from our group, this article also reviews publications from other researchers. The novel class of dental materials with triple benefits of self-healing, antibacterial and remineralization capabilities offer the much-needed improvements to address the two main reasons for restoration failures: fracture and secondary caries. They are expected to have potential for a wide range of dental and biomedical applications to overcome the current challenges and prolong the restoration life.

Objectives (1) To develop a novel bioactive root canal sealer with antibiofilm and remineralization properties using dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP); (2) investigate the effects on E. faecalis biofilm inhibition, sealer flow and sealing ability, compared with an epoxy-resin-based sealer AH Plus; and (3) investigate the calcium (Ca) and phosphate (P) ion release from the sealers. Methods A series of dual-cure endodontic sealers were formulated with DMAHDM and NACP at 5% and 20% by mass, respectively. Flow properties and sealing ability of the sealers were measured. Colony-forming units (CFU), live/dead assay, and polysaccharide production of biofilms on sealers were determined. Ca and P ion releases from the sealers were measured. Results The new sealer containing 20% NACP and 5% DMAHDM yielded a paste flow of (28.99 ± 0.69) mm, within the range of ISO recommendations. The sealing properties of the sealer with 5% DMAHDM and 20% NACP were similar to a commercial control (p > 0.05). The sealer with DMAHDM decreased E. faecalis biofilm CFU by more than 4 orders of magnitude, compared to AH plus and experimental controls. The sealer with 20% NACP and 5% DMAHDM had relatively high levels of Ca and P ion release necessary for remineralization. Conclusions A new bioactive endodontic sealer was developed with strong antibiofilm activity against E. faecalis biofilms and high levels of Ca and P ion release for remineralization, without compromising the paste flow and sealing properties. Clinical significance The bioactive antibacterial and remineralizing root canal sealer is promising to inhibit E. faecalis biofilms to prevent endodontic treatment failure and secondary endodontic infections, while releasing high levels of Ca and P ions that could remineralize and strengthen the tooth structures and potentially prevent future root fractures and teeth extractions.

Resin cements with remineralizing and antibacterial properties are favorable for inhibition of caries. The objectives of this study were: (1) to investigate the capability of the novel dimethylaminohexadecyl-methacrylate (DMAHDM) and nano-sized amorphous calcium phosphate (NACP) containing cement to reduce saliva microcosm biofilm, and (2) to investigate the long-term ion release, recharge, and re-release of DMAHDM-NACP cement.Pyromellitic glycerol dimethacrylate (PMGDM) and ethoxylated bisphenol-A-dimethacrylate (EBPADMA) were used to make PEHB monomer. Five cements were fabricated: (1) PEHB+0%NACP+0%DMAHDM (experimental control); (2) PEHB+25%NACP+0%DMAHDM, (3) PEHB+25%NACP+0%DMAHDM; (4) PEHB+25%NACP+3%DMAHDM; (5) PEHB+25%NACP+5%DMAHDM. RelyX luting cement was used as commercial control. Colony-forming units (CFU), lactic acid production, metabolic activities, and minimum inhibitory concentration (MIC) were performed. Long-term Calcium (Ca) and phosphate (P) ion release, recharge, and re-release were assessed.Compared to experimental and commercial controls, the NACP-DMAHDM cement significantly reduced CFU biofilm by 2-3 orders of magnitude, metabolic activities from 0.24±0.06 AIncorporating DMAHDM and NACP into resin-based crown cement provides strong antibacterial action against saliva microcosm biofilm and presents a high level of Ca and P ion recharge abilities, exhibiting long-term Ca and P ion release and remineralization potential.Resin based cement containing NACP and DMAHDM were developed with remineralizing and potent antibacterial effects. This cement formulation showed ion release and remineralization potential and are promising formulations to inhibit the incidence of recurrent caries and could promote remineralization and be sustainable for the long term.

Recurrent caries often occurs and is a primary reason for the failure of dental composite restorations. The objectives of this study were to: (1) develop a bioactive composite containing dimethylaminohexadecyl methacrylate (DMAHDM), (2) investigate its antibacterial effects and suppression on biofilm growth, and (3) investigate its ability to modulate biofilm species composition for the first time. DMAHDM was incorporated into a composite at mass% of 0%, 0.75%, 1.5%, 2.25% and 3%. A commercial composite Heliomolar served as a comparative control. A biofilm model consisting of Streptococcus mutans (S. mutans), Streptococcus sanguinis (S. sanguinis) and Streptococcus gordonii (S. gordonii) was tested by growing biofilms for 48 h and 72 h on composites. Colony-forming units (CFUs), metabolic activity and live/dead staining were evaluated. Lactic acid and polysaccharide productions were measured to assess biofilm cariogenicity. TaqMan real-time polymerase chain reaction was used to determine the proportion of each species in the biofilm. DMAHDM-containing composite had a strong anti-biofilm function, reducing biofilm CFU by 2–3 orders of magnitude, compared to control composite. Biofilm metabolic activity, lactic acid and polysaccharides were decreased substantially, compared to control (p < 0.05). At 72 h, the cariogenic S. mutans proportion in the biofilm on the composite with 3% DMAHDM was 19.9%. In contrast, an overwhelming S. mutans proportion of 92.2% and 91.2% existed in biofilms on commercial control and 0% DMAHDM, respectively. In conclusion, incorporating DMAHDM into dental composite: (1) yielded potent anti-biofilm properties; (2) modulated the biofilm species composition toward a non-cariogenic tendency. The new DMAHDM composite is promising for applications in a wide range of tooth cavity restorations to modulate oral biofilm species and combat caries.

There has been no report on the effect of incorporating protein repellent 2-methacryloyloxyethyl phosphorylcholine (MPC) into a composite containing nanoparticles of amorphous calcium phosphate (NACP) on calcium (Ca) and phosphate (P) ion rechargeability. The objectives of this study were to develop a Ca and P ion-rechargeable and protein-repellent composite for the first time, and investigate the effects of MPC and NACP on mechanical properties, protein-repellency, anti-biofilm effects, and Ca and P ion recharge and re-release.NACP were synthesized using a spray-drying technique. The resin contained ethoxylated bisphenol A dimethacrylate (EBPADMA) and pyromellitic glycerol dimethacrylate (PMGDM). Three NACP composites were made with 0 (control), 1.5%, and 3% of MPC. NACP (20%) and glass particles (50%) were also added into the resin. Protein adsorption was measured using a micro-bicinchoninic acid (BCA) method. A human saliva microcosm biofilm model was used to determine biofilm metabolic activity, lactic acid, and colony-forming units (CFU). Ca and P ion recharge and re-release were measured using a spectrophotometric method.Flexural strengths and moduli of CaP-rechargeable composites matched those of a commercial composite without CaP rechargeability (p0.1). Adding 1.5% and 3% MPC reduced protein adsorption to 1/3 and 1/5, respectively, that of commercial composite (p0.05). Adding 3% MPC suppressed biofilm metabolic activity and lactic acid production, and reduced biofilm CFU by nearly 2 logs. All three NACP composites had excellent ion rechargeability and higher levels of ion re-releases. One recharge yielded continuous ion release for 21 days. The release was maintained at the same level with increasing number of recharge cycles, indicating long-term ion release. Incorporation of MPC did not compromise the CaP ion rechargeability.Incorporating 3% MPC into NACP nanocomposite greatly reduced protein adsorption, biofilm growth and lactic acid, decreasing biofilm CFU by nearly 2 logs, without compromising Ca and P recharge. This protein-repellent NACP-MPC rechargeable composite with long-term remineralization is promising for tooth restorations to inhibit secondary caries.

Objectives The objectives were to develop a calcium (Ca) and phosphate (P) ion-rechargeable and protein-repellent adhesive containing nanoparticles of amorphous calcium phosphate (NACP) and 2-methacryloyloxyethyl phosphorylcholine (MPC), and investigate the MPC effects on ion recharge and re-releases for the first time. Methods Pyromellitic glycerol dimethacrylate and ethoxylated bisphenol-A dimethacrylate were used to fabricate adhesive PEHB. Six adhesives were tested: (1) Scotchbond (SBMP); (2) PEHB, (3) PEHB + 20%NACP; (4) PEHB + 30%NACP; (5) PEHB + 20%NACP+3%MPC; (6) PEHB + 30%NACP+3%MPC. Dentin shear bond strength, Ca/P ion release, recharge and re-release, and protein adsorption were measured. A microcosm biofilm model was tested for lactic-acid production and colony-forming units (CFU). Results Adding NACP + MPC did not negatively affect dentin bond strength (p > 0.1). With increasing the number of recharge/re-release cycles, the Ca/P ion re-release reached similarly higher levels (p > 0.1), indicating long-term remineralization capability. One recharge enabled the adhesives to have continued re-releases for 21 days. Incorporation of 3% MPC yielded 10-fold decrease in protein adsorption, and 1–2 log decrease in biofilm CFU. Conclusions The new rechargeable adhesive with MPC + 30%NACP greatly reduced protein adsorption, biofilm growth and lactic acid. Incorporation of MPC did not compromise the excellent Ca/P ion release, rechargeability, and dentin bond strength. Clinical significance Novel bioactive adhesive containing MPC + NACP is promising to repel proteins and bacteria, and inhibit secondary caries at the restoration margins. The method of NACP + MPC to combine CaP-recharge and protein-repellency is applicable to the development of a new generation of materials including composites and cements to suppress oral biofilms and plaque formation and protect tooth structures.

The purpose of this study was to investigate the physical and antibacterial properties of a resin sealer mixed with a quaternary ammonium compound, dimethylaminododecyl methacrylate (DMAHDM) and nanosilver (NAg).A pilot study was completed to determine the highest concentrations of DMAHDM and NAg that did not significantly alter the physical properties (setting time, flow, solubility, and dimensional change) of AH Plus (Dentsply Sirona, York, PA) when added to the sealer. These concentrations were selected to create a modified resin sealer (mAH Plus). A modified direct contact test evaluated antibacterial properties of AH Plus, DMAHDM + AH Plus, NAg + AH Plus, and mAH Plus at days 1, 7, and 14 against Enterococcus faecalis.Concentrations of 2.5% DMAHDM and 0.15% NAg were added to AH Plus. The flow of mAH Plus was significantly decreased but still within American National Standards Institute/American Dental Association specifications. There were no significant differences in setting time, solubility, or dimensional change. On day 1, 0.15% NAg + AH Plus, 2.5% DMAHDM + AH Plus, and mAH Plus were significantly more effective against E. faecalis compared with AH Plus (P .05). On days 7 through 14, 2.5% DMAHDM + AH Plus and mAH Plus continued to be significantly more antibacterial than AH Plus (P .05).The addition of 0.15% NAg and 2.5% DMAHDM did not adversely affect the physical properties of AH Plus, and mAH Plus was significantly more antibacterial against E. faecalis.

Objective Composites with remineralizing and antibacterial properties are favorable for caries inhibition. The objectives of this study were to develop a new bioactive nanocomposite with remineralizing and antibiofilm properties by incorporating dimethylaminohexadecyl methacrylate (DMAHDM) and nano-calcium fluoride (nCaF2). Methods nCaF2 was produced via a spray-drying method and integrated at 15% mass fraction into composite. DMAHDM was added at 3% mass fraction. Mechanical properties and F and Ca ion releases were assessed. Colony-forming units (CFU), lactic acid and metabolic activity of biofilms on composites were performed. Results The new composites had flexural strengths of (95.28±6.32) MPa and (125.93±7.49) MPa, which were within the ISO recommendations. Biofilm CFU were reduced by 3–4 log (p Conclusions New nanocomposites were developed with good mechanical properties, potent antibacterial activity against salivary biofilms, and high F and Ca ion releases with potential for remineralization. Clinical Significance Novel nanocomposites using nCaF2 and DMAHDM were developed with potent antibacterial and remineralizing effects and high F and Ca ion releases. They are promising to inhibit recurrent caries, promote remineralization, and possess long-term sustainability.

Objectives The objectives of this study were to develop a self-healing dental composite containing poly(urea-formaldehyde) (PUF) shells with triethylene glycol dimethacrylate (TEGDMA) and N,N -dihydroxyethyl- p -toluidine (DHEPT) as healing liquid, and to investigate the mechanical properties of the composite and its self-healing efficacy after water-aging for 6 months. Methods PUF microspheres were synthesized encapsulating a TEGDMA–DHEPT healing liquid. Composite containing 30% of a resin matrix and 70% of glass fillers by mass was incorporated with 0%, 2.5%, 5%, 7.5% and 10% of microcapsules. A flexural test was used to measure flexural strength and elastic modulus. A single edge V-notched beam method was used to measure fracture toughness ( K IC ) and self-healing efficacy. Specimens were water-aged at 37 °C for 1 day to 6 months and then tested for self-healing. Fractured specimens were healed while being immersed in water to examine self-healing efficacy, in comparison with that in air. Results Incorporation of up to 7.5% of microcapsules into the resin composite achieved effective self-healing, without adverse effects on the virgin mechanical properties of the composite ( p > 0.1). An excellent self-healing efficacy of 64–77% recovery was obtained (mean ± sd; n = 6). Six months of water-aging did not decrease the self-healing efficacy compared to 1 day ( p > 0.1). Exposure to water did not decrease the healing efficacy, compared to that healed in air ( p > 0.1). Conclusions A composite was developed with excellent self-healing efficacy even while being immersed in water. The self-healing efficacy did not decrease with increasing water-aging time for 6 months. Clinical significance The novel self-healing composite may be promising for dental applications to heal cracks, resist fracture, and increase the durability and longevity.

Objectives To identify antibacterial additives and screening/assessment approaches used to evaluate the antibacterial activity of resin-based restorative dental materials containing these additives. Data In vitro studies that compared the antibacterial effects of resin-based restorative dental materials with and without antibacterial additives were screened. Risk bias was assessed, and the following data were extracted: antibacterial additive, parental dental material, curing mode, bacterial growth outcome assessment, samples used as a substrate for bacterial growth, inoculum complexity, and culture time as an indicator of biofilm maturity. Source Arksey and O’Malley’s five stages framework using Medline (OVID), EMBASE, and Scopus (Elsevier) databases guided this review. Study selection From 6503 studies initially identified, 348 studies were considered eligible for full-text screening, and 153 were included for data extraction. Almost all studies have a high sampling bias related to both sample size and blindness. Quaternary ammonium monomers were the most investigated additive (45 %), and the most prevailing parental material was resin composite (49 %). There was extensive methodological heterogeneity among the studies for outcome assessment with the majority using resin composite disks (78 %), mono-species Streptococcus mutans as the inoculum (54 %), and a relatively short period of biofilm growth (≤24 h). Conclusion The findings herein present the urgent need for improved biological efficacy studies in this important and exciting field. There is a need for efforts to improve study designs to mimic the oral environment in vivo and to develop standardized methods to help understand and optimize these materials. Clinical significance Most studies that incorporate antibacterial additives into resin-based materials claim promising results by bacterial reduction. However, these results should be interpreted with caution due to significant variation in the methods applied for quantifying bacterial growth, the frequent lack of complexity in the biofilms, and the often-short duration of biofilm growth.

The S.mutans biofilm formation is an ongoing challenge for the long-term survival of dental resins. In this study, we report a strategy to endow antibacterial ability to resin infiltrants, a new and conservative class of material for microinvasive treatments. Polyhexamethylene guanidine hydrochloride was added at 0.5 or 1 wt%. One group without PHMGH was used as control. The antimicrobial performance of biointeractive dental resin infiltrant was evaluated against Streptococcus mutans planktonic cells and direct exposure biofilm models. The quality of the polymer was assessed by the degree of monomer conversion using Fourier-transform infrared spectroscopy. Data were analyzed by one-way ANOVA and Tukey (α = 0.05). The complete eradication of S. mutans biofilm was achieved when in contact with the resin infiltrants containing PHMGH at 1 wt% employed bactericidal and biofilm inhibition activity through a “contact–kill and release” mode of action. More importantly, the polyhexamethylene guanidine hydrochloride conveys biofilm inhibition to resin infiltrants while not adversely affect the critical physical properties of this material. This work may provide a simple pathway to develop antibacterial dental resin infiltrants.

Dental caries (tooth decay) is a prevalent disease. Resin composites have become the most commonly used materials to restore caries due to their direct-filling capability, tooth-colored esthetics, and photo cure-on-demand property. However, it has been reported that the current generation of composite restorations has a relatively high failure rate due to secondary caries and bulk fracture. Therefore, efforts have been made to develop a new generation of antibacterial and therapeutic dental polymeric composites to suppress caries and increase the longevity of the restorations. These new materials have demonstrated the effects to inhibit the growth of oral biofilms and plaques, reduce bacterial acid production, regenerate the lost tooth minerals, and self-heal cracks to regain the load-bearing capabilities. This article reviews the cutting-edge development for this new generation of dental restorative materials.

Objective Bulk fracture is one of the primary reasons for resin-based dental restoration failures. To date, there has been no report on the use of polymerizable dental monomers with acceptable biocompatibility to develop a resin with substantial self-healing capability. The objectives of this study were to: (1) develop a self-healing resin containing microcapsules with triethylene glycol dimethacrylate (TEGDMA)- N , N -dihydroxyethyl- p -toluidine (DHEPT) healing liquid in poly(urea-formaldehyde) (PUF) shells for the first time, and (2) determine the physical and mechanical properties, self-healing efficiency, and fibroblast cytotoxicity. Methods Microcapsules of polymerizable TEGDMA-DHEPT in PUF were prepared via an in situ polymerization method. Microcapsules were added into a BisGMA-TEGDMA resin at microcapsule mass fractions of 0%, 5%, 10%, 15% and 20%. A flexural test was used to measure composite strength and elastic modulus. A single edge V-notched beam method was used to measure fracture toughness K IC and self-healing efficiency. Results Flexural strength and elastic modulus (mean ± sd; n = 6) of resin containing 5–15% microcapsules were similar to control without microcapsules ( p > 0.1). Adding microcapsules into the resin increased the virgin K IC , which was about 40% higher at 15% microcapsules than that with 0% microcapsules ( p IC . A self-healing efficiency of about 65% in K IC recovery was obtained with 10–20% microcapsules. All specimens with 0–20% microcapsules had fibroblast viability similar to control without resin eluents ( p > 0.1). Significance Self-healing dental resin containing microcapsules with polymerizable TEGDMA-DHEPT healing liquid in PUF shells were prepared for the first time with excellent self-healing capability. These microcapsules and self-healing resins containing them may be promising for dental restorations to heal cracks/damage and increase durability.

Background Ultraconservative removal of carious tissue is becoming increasingly highlighted for management of deep caries lesions, and combined with an antimicrobial photochemistry-based treatment modality (PACT), this approach can be enhanced favoring dental tissue repair and preservation. The aim was to investigate the effectiveness of PACT using a light emitting diode (LED) associated with a photosensitizer toluidine blue ortho (TBO) on deep caries lesions. Methods For that, a single blind, randomized, controlled, split-mouth clinical trial where 45 patients with at least two deep carious lesions on permanent posterior teeth was performed. The primary intervention was deep caries lesion management with disinfection of remaining dentin tissue using PACT. Bacterial counts were measured following treatments as the main outcome. The remaining dentinal samples of each lesion were treated with either non-PACT-control or PACT. The PACT procedure were characterized by 100 μg mL −1 TBO followed by 94 J cm −2 LED irradiation. Samples of dentin were collected before and immediately after treatments for microbiological analysis of total viable bacteria, mutans streptococci and Lactobacillus spp. counts. Microbial reduction was data were submitted to unpaired t test ( α = 5%). Results PACT led to statistically significant reductions in mutans streptococci (1.08 ± 1.20 log), Lactobacillus spp. (1.69 ± 1.37 log), and total viable bacteria (1.07 ± 1.01 log) compared to the control, which showed log reductions respectively of 0.05 ± 0.49, 0.52 ± 0.89, and 0.47 ± 0.77 for the same microorganisms. Conclusion Dentin from deep carious lesions treated with PACT showed a decrease in cariogenic microbial load.

Biofilm acids contribute to secondary caries, which is a main reason for dental restoration failures. The objectives of this study were to: (1) develop a protein-repellent and antibacterial composite, and (2) investigate the effects of combining 2-methacryloyloxyethyl phosphorylcholine (MPC) with quaternary ammonium dimethylaminohexadecyl methacrylate (DMAHDM) on composite mechanical properties and biofilm response for the first time.MPC, DMAHDM and glass particles were mixed into a dental resin composite. Mechanical properties were measured in three-point flexure. Protein adsorption onto the composites was measured by a micro bicinchoninic acid method. A human saliva microcosm model was used to grow biofilms on composites. Colony-forming unit (CFU) counts, live/dead assay, metabolic activity, and lactic acid production of biofilms were determined.Incorporation of 3% MPC and 1.5% DMAHDM into composite achieved protein-repellent and antibacterial capabilities without compromising the mechanical properties. Composite with 3% MPC+1.5% DMAHDM had protein adsorption that was 1/10 that of a commercial composite (p0.05). The composite with 3% MPC+1.5% DMAHDM had much greater reduction in biofilm growth than using MPC or DMAHDM alone (p0.05). Biofilm CFU counts on composite with 3% MPC+1.5% DMAHDM were more than three orders of magnitude lower than that of commercial control.Dental composite with a combination of strong protein-repellent and antibacterial capabilities was developed for the first time. Composite containing MPC and DMAHDM greatly reduced biofilm growth and lactic acid production, without compromising mechanical properties of the composite.Novel composite with MPC and DMAHDM greatly reduced biofilm activity and is promising to inhibit secondary caries. The dual agents of MPC plus DMAHDM may have wide applicability to other dental materials.

Objectives Biofilms at tooth-restoration margins can produce acids and cause secondary caries. A protein-repellent adhesive resin can potentially inhibit bacteria attachment and biofilm growth. However, there has been no report on protein-repellent dental resins. The objectives of this study were to develop a protein-repellent bonding agent incorporating 2-methacryloyloxyethyl phosphorylcholine (MPC), and to investigate its resistance to protein adsorption and biofilm growth for the first time. Methods MPC was incorporated into Scotchbond Multi-Purpose (SBMP) at 0%, 3.75%, 7.5%, 11.25%, and 15% by mass. Extracted human teeth were used to measure dentine shear bond strengths. Protein adsorption onto resins was determined by a micro bicinchoninic acid (BCA) method. A dental plaque microcosm biofilm model with human saliva as inoculum was used to measure biofilm metabolic activity and colony-forming unit (CFU) counts. Results Adding 7.5% MPC into primer and adhesive did not decrease the dentine bond strength, compared to control ( p > 0.1). Incorporation of 7.5% of MPC achieved the lowest protein adsorption, which was 20-fold less than that of control. Incorporation of 7.5% of MPC greatly reduced bacterial adhesion, yielding biofilm total microorganism, total streptococci, and mutans streptococci CFU that were an order of magnitude less than control. Conclusions A protein-repellent dental adhesive resin was developed for the first time. Incorporation of MPC into primer and adhesive at 7.5% by mass greatly reduced the protein adsorption and bacterial adhesion, without compromising the dentine bond strength. Clinical significance The novel protein-repellent primer and adhesive are promising to inhibit biofilm formation and acid production, to protect the tooth-restoration margins and prevent secondary caries.

Objectives Fluoride-containing orthodontic cements are used to combat white spot lesions (WSLs) in enamel. However, the fluoride (F) ion releases from these cements are relatively low and short-term. The objectives of this study were to develop a novel rechargeable orthodontic cement with nanoparticles of calcium fluoride (nCaF2) to provide long-term and high levels of F release, and to investigate F recharge and physical and cytotoxic properties. Methods The nCaF2 with a mean particle size of 58 nm were synthesized using a spray-drying method. Pyromellitic glycerol dimethacrylate (PMGDM), ethoxylated bisphenol A dimethacrylate (EBPADMA), 2-hydroxyethyl methacrylate (HEMA) and bisphenol A glycidyl dimethacrylate (BisGMA) were used to prepare the cements (denoted PE and PEHB resins). A resin-modified glass ionomer (RMGI) served as control. Enamel shear bond strength (SBS), cytotoxicity, and F ion recharge and re-release were evaluated. Results nCaF2 cements had good SBS and excellent biocompatibility that were comparable to RMGI (p > 0.1). After a recharge for 1 min, the F re-release from PEHB + 30%nCaF2 cement was 80% higher than RMGI (p 0.1). Conclusions A novel F ion-rechargeable orthodontic cement containing nCaF2 was developed with clinically acceptable enamel SBS, good biocompatibility, and sustained F ion recharge and re-release that were 1.8 folds that of a commercial RMGI. Clinical Significance Novel rechargeable nCaF2 orthodontic cement is promising to provide the needed long-term and high levels of F ion releases to inhibit WSLs in orthodontics.

Objectives The objectives of this study were to develop a resin-modified glass ionomer containing nanoparticles of calcium fluoride (nCaF 2 ) and dimethylaminohexadecyl methacrylate (DMAHDM) for the first time and investigate the antibacterial and remineralization properties. Methods nCaF 2 was synthesized using a spray-drying method and characterized using a transmission electron microscope. Twenty weight percentage (wt%) nCaF 2 and 3 wt% DMAHDM were incorporated into a RMGI (GC Ortho LC). Enamel shear bond strength (SBS) and cytotoxicity were determined. Fluoride (F) and calcium (Ca) ion releases were assessed. Biofilm live/dead staining, metabolic activity, polysaccharide and lactic production, and colony-forming units (CFU) were evaluated. The remineralization ability was determined by measuring the effects of cements on enamel surface hardness and lesion depth. Results Incorporating 20 wt% nCaF 2 and 3 wt% DMAHDM did not compromise the SBS (p > 0.1). The decrease of pH from 7.0 to 4.0 significantly increased the F and Ca ion releases. The new cement greatly reduced the metabolic activity, polysaccharide and lactic acid productions, and lowered the biofilm CFU by 3 log, compared to commercial control (p Conclusions The novel orthodontic cement containing nCaF 2 and DMAHDM achieved much stronger antibacterial and remineralization capabilities and greater enamel hardness than the commercial control did, without compromising the orthodontic bracket-enamel SBS and biocompatibility. Clinical Significance The novel bioactive and nanostructured orthodontic cement is promising to inhibit enamel demineralization, white spot lesions and caries in orthodontic treatments.

Objectives Insufficient radiant exposure (J/cm2) may provide an early trigger in a cascade of detrimental responses on incrementally-place composite, especially the bottom layer. This study aimed to assess the influence of poor radiant exposure, the degree of conversion (%DC), water sorption/ solubility and S. mutans biofilm formation on conventional, incrementally placed composites and to establish a relationship between these factors. Methods Two light units operating at 600 and 1000 mW/cm2 and four most common operator-dependent curing conditions had the radiant exposure (RE) recorded. All the specimens were subjected to S. mutans biofilm model for 14 days. The %DC, biofilm formation expressed by colony-forming units (CFU), water sorption/ solubility and surface roughness/ SEM were assessed. Data were submitted to two-way ANOVA and Tukey post-hoc test (α = 0.05). Pearson correlation was also determined. Results The influence of RE on S. mutans CFU values and DC are dependent on the curing conditions and irradiance (p Conclusion Poor, deficient curing procedures provide an early trigger in a negative pathway of events for incrementally-place dental composite including a biological response by increased biofilm formation by S. mutans, a relevant factor for secondary caries development. Significance The susceptibility to variation in the outcomes was RE -dependent. The optimization of the curing procedures ensures the maximum performance in the chain of events involved in the light curing process of resin-based materials and potentially reduce the risk factors of secondary caries development.

Nanotechnology has been applied to dental materials as an innovative concept for the development of materials with better properties and anticaries potential. In this review we discuss the current progress and future applications of functional nanoparticles incorporated in dental restorative materials as useful strategies to dental caries management. We also overview proposed antimicrobial and remineralizing mechanisms. Nanomaterials have great potential to decrease biofilm accumulation, inhibit the demineralization process, to be used for remineralizing tooth structure, and to combat caries-related bacteria. These results are encouraging and open the doors to future clinical studies that will allow the therapeutic value of nanotechnology-based restorative materials to be established.

Secondary caries is the main reason for restoration failure, and replacement of the failed restorations accounts for 50-70% of all restorations. Antibacterial adhesives could inhibit residual bacteria in tooth cavity and invading bacteria along the margins. Calcium (Ca) and phosphate (P) ion release could remineralize the lesions. The objectives of this study were to incorporate nanoparticles of silver (NAg) and nanoparticles of amorphous calcium phosphate (NACP) into adhesive for the first time, and to investigate the effects on dentin bond strength and plaque microcosm biofilms.Scotchbond multi-purpose adhesive was used as control. NAg were added into primer and adhesive at 0.1% by mass. NACP were mixed into adhesive at 10%, 20%, 30% and 40%. Microcosm biofilms were grown on disks with primer covering the adhesive on a composite. Biofilm metabolic activity, colony-forming units (CFU) and lactic acid were measured.Human dentin shear bond strengths (n=10) ranged from 26 to 34 MPa; adding NAg and NACP into adhesive did not decrease the bond strength (p0.1). SEM examination revealed resin tags from well-filled dentinal tubules. Numerous NACP infiltrated into the dentinal tubules. While NACP had little antibacterial effect, NAg in bonding agents greatly reduced the biofilm viability and metabolic activity, compared to the control (p0.05). CFU for total microorganisms, total streptococci, and mutans streptococci on bonding agents with NAg were an order of magnitude less than those of the control. Lactic acid production by biofilms for groups containing NAg was 1/4 of that of the control.Dental plaque microcosm biofilm viability and acid production were greatly reduced on bonding agents containing NAg and NACP, without compromising dentin bond strength. The novel method of incorporating dual agents (remineralizing agent NACP and antibacterial agent NAg) may have wide applicability to other dental bonding systems.