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Recurrent caries remain a persistent concern, often linked to microleakage and a lack of bioactivity in contemporary dental composites. Our study aims to address this issue by developing a low-shrinkage-stress nanocomposite with antibiofilm and remineralization capabilities, thus countering the progression of recurrent caries. In the present study, we formulated low-shrinkage-stress nanocomposites by combining triethylene glycol divinylbenzyl ether and urethane dimethacrylate, incorporating dimethylaminododecyl methacrylate (DMADDM), along with nanoparticles of calcium fluoride (nCaF2) and nanoparticles of amorphous calcium phosphate (NACP). The biofilm viability, biofilm metabolic activity, lactic acid production, and ion release were evaluated. The novel formulations containing 3% DMADDM exhibited a potent antibiofilm activity, exhibiting a 4-log reduction in the human salivary biofilm CFUs compared to controls (p < 0.001). Additionally, significant reductions were observed in biofilm biomass and lactic acid (p < 0.05). By integrating both 10% NACP and 10% nCaF2 into one formulation, efficient ion release was achieved, yielding concentrations of 3.02 ± 0.21 mmol/L for Ca, 0.5 ± 0.05 mmol/L for P, and 0.37 ± 0.01 mmol/L for F ions. The innovative mixture of DMADDM, NACP, and nCaF2 displayed strong antibiofilm effects on salivary biofilm while concomitantly releasing a significant amount of remineralizing ions. This nanocomposite is a promising dental material with antibiofilm and remineralization capacities, with the potential to reduce polymerization-related microleakage and recurrent caries. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A common reason for dental composite restoration failure is recurrent caries at the margins. Our objectives were to: (1) develop a novel low-shrinkage-stress, antibacterial and remineralizing resin composite; (2) evaluate the effects of dimethylaminohexadecyl methacrylate (DMAHDM) on mechanical properties, biofilm inhibition, calcium (Ca) and phosphate (P) ion release, degree of conversion, and shrinkage stress on the new low-shrinkage-stress resin composite for the first time. The resin consisted of urethane dimethacrylate (UDMA) and triethylene glycol divinylbenzyl ether (TEG-DVBE) with high resistance to salivary hydrolytic degradation. Composites were made with 0%–8% of DMAHDM for antibacterial activity, and 20% of nanoparticles of amorphous calcium phosphate (NACP) for remineralization. Mechanical properties and Streptococcus mutans biofilm growth on composites were assessed. Ca and P ion releases, degree of conversion and shrinkage stress were evaluated. Adding 2–5% DMAHDM and 20% NACP into the low-shrinkage-stress composite did not compromise the mechanical properties (p > 0.05). The incorporation of DMAHDM greatly reduced S. mutans biofilm colony-forming units by 2–5 log and lactic acid production by 7 folds, compared to a commercial composite (p < 0.05). Adding 5% DMAHDM did not compromise the Ca and P ion release. The low-shrinkage-stress composite maintained a high degree of conversion of approximately 70%, while reducing the shrinkage stress by 37%, compared to a commercial control (p < 0.05). The bioactive low-shrinkage-stress composite reduced the polymerization shrinkage stress, without compromising other properties. Increasing the DMAHDM content increased the antibacterial effect in a dose-dependent manner. [ABSTRACT FROM AUTHOR]

Objectives: A previous study showed that the combination of poly(amido amine) (PAMAM) and rechargeable composites with nanoparticles of amorphous calcium phosphate (NACP) induced dentin remineralization in an acidic solution with no initial calcium (Ca) and phosphate (P) ions, mimicking the oral condition of individuals with dry mouths. However, the frequent fluid challenge in the oral cavity may decrease the remineralization capacity. Therefore, the objective of the present study was to investigate the remineralization efficacy on dentin in an acid solution via PAMAM + NACP after fluid challenges for the first time. Methods: The NACP nanocomposite was stored in a pH 4 solution for 77 days to exhaust its Ca and P ions and then recharged. Demineralized dentin samples were divided into four groups: (1) control dentin, (2) dentin coated with PAMAM, (3) dentin with recharged NACP composite, and (4) dentin with PAMAM + recharged NACP. PAMAM-coated dentin was shaken in phosphate-buffered saline for 77 days to desorb PAMAM from dentin. Samples were treated in pH 4 lactic acid with no initial Ca and P ions for 42 days. Results: After 77 days of fluid challenge, PAMAM failed to prevent dentin demineralization in lactic acid. The recharged NACP nanocomposite raised the pH to above 6.5 and re-released more than 6.0 and 4.0 mmol/L Ca and P ions daily, respectively, which inhibited further demineralization. In contrast, the PAMAM + NACP combined method induced great dentin remineralization and restored the dentin microhardness to 0.54 ± 0.04 GPa, which approached that of sound dentin (P = 0.426, P > 0.05). Conclusions: The PAMAM + NACP combination achieved dentin remineralization in an acid solution with no initial Ca and P ions, even after severe fluid challenges. Clinical relevance: The novel PAMAM + NACP has a strong and sustained remineralization capability to inhibit secondary caries, even for individuals with dry mouths. [ABSTRACT FROM AUTHOR]

Objectives: Dental caries is closely associated with acid-producing bacteria, and Streptococcus mutans is one of the primary etiological agents. Bacterial accumulation and dental demineralization lead to destruction of bonding interface, thus limiting the longevity of composite. The present study investigated remineralization effectiveness of adhesive containing nanoparticles of amorphous calcium phosphate (NACP) in a stimulated oral biofilm environment. Methods: The enamel blocks were immersed in demineralization solution for 72 h to imitate artificial initial carious lesion and then subjected to a Streptococcus mutans biofilm for 24 h. All the samples then underwent 4-h demineralization in brain heart infusion broth with sucrose (BHIS) and 20-h remineralization in artificial saliva (AS) for 7 days. The daily pH of BHIS after 4-h incubation, lactic acid production, colony-forming unit (CFU) count, and content of calcium (Ca) and phosphate (P) in biofilm were evaluated. Meanwhile, the remineralization effectiveness of enamel was analyzed by X-ray diffraction (XRD), surface microhardness testing, transverse microradiography (TMR) and scanning electron microscopy (SEM). Results: The NACP adhesive released abundant Ca and P, achieved acid neutralization, reduced lactic acid production, and lowered CFU count (P < 0.05). Enamel treated with NACP adhesive demonstrated the best remineralization effectiveness with remineralization value of 52.29 ± 4.79% according to TMR. Better microhardness recovery of cross sections and ample mineral deposits were also observed in NACP group. Conclusions: The NACP adhesive exhibited good performance in remineralizing initial enamel lesion with cariogenic biofilm. Significance: The NACP adhesive is promising to be applied for the protection of bonding interface, prevention of secondary caries, and longevity prolonging of the restoration. [ABSTRACT FROM AUTHOR]

The aims are: (a) To develop the first low‐shrinkage‐stress nanocomposite with antibacterial and remineralization capabilities through the incorporation of dimethylaminododecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP); (b) to investigate the effects of the new composite on biofilm inhibition, mechanical properties, shrinkage stress, and calcium (Ca) and phosphate (P) ion releases. The low‐shrinkage‐stress resin consisted of urethane dimethacrylate and triethylene glycol divinylbenzyl ether. Composite was formulated with 3% DMAHDM and 20% NACP. Mechanical properties, shrinkage stress, and degree of conversion were evaluated. Streptococcus mutans biofilm growth on composites was assessed. Ca and P ion releases were measured. The shrinkage stress of the low‐shrinkage‐stress composite containing 3% DMAHDM and 20% NACP was 36% lower than that of traditional composite control (p < 0.05), with similar degrees of conversion of 73.9%. The new composite decreased the biofilm colony‐forming unit by 4 log orders and substantially reduced biofilm lactic acid production compared to control composite (p < 0.05). Incorporating DMAHDM to the low‐shrinkage‐stress composite did not adversely affect the Ca and P ion release. A novel bioactive nanocomposite was developed with low shrinkage stress, strong antibiofilm activity, and high levels of ion release for remineralization, without undermining the mechanical properties and degree of conversion. [ABSTRACT FROM AUTHOR]

Human induced pluripotent stem cells (hiPSCs) are exciting for regenerative medicine due to their multi-potent differentiation. SB431542 bioactive molecule can activate bone morphogenetic protein-signalling in osteoblasts. The objectives were to: (1) develop a novel injectable calcium phosphate cement (CPC)-SB431542 scaffold for dental/craniofacial bone engineering; and (2) investigate cell proliferation and osteo-differentiation of hiPSC-derived mesenchymal stem cells (hiPSC-MSCs) on CPC-SB431542 scaffold. Three groups were tested: CPC control; CPC with SB431542 inside CPC (CPCSM); CPC with SB431542 in osteogenic medium (CPC+SMM). SB431542 in CPC promoted stem cell proliferation and viability. hiPSC-MSCs differentiated into osteogenic lineage and synthesized bone minerals. CPC with SB431542 showed much greater osteo-expressions and more bone minerals than those without SB431542. In conclusion, hiPSC-MSCs on CPC scaffold containing SB431542 showed excellent osteo-differentiation and bone mineral synthesis for the first time. CPC was a suitable scaffold for delivering stem cells and SB431542 to promote bone regeneration in dental/craniofacial applications. [ABSTRACT FROM AUTHOR]

A low-shrinkage-stress (LSS), antibacterial and remineralizing nanocomposite was recently developed; however, validation of its long-term antibacterial potency in modulating human salivary-derived biofilm is an unmet need. This study aimed to evaluate the antibacterial effect of the bioactive LSS composite before and after aging in acidic solution for 90 days using a multi-species biofilm model, and to evaluate its cytotoxicity. The LSS composite consisted of urethane dimethacrylate (UDMA) and triethylene glycol divinylbenzyl ether (TEG-DVBE), 3% dimethylaminohexadecyl methacrylate (DMAHDM) and 20% nanoparticles of amorphous calcium phosphate (NACP). Biofilm colony-forming units (CFU), lactic acid production, and confocal laser scanning microscopy (3D biofilm) were evaluated before and after three months of aging. Cytotoxicity was assessed against human gingival fibroblasts (HGF). The new LSS composite presented the lowest biofilm CFU, lactic acid and biofilm biomass, compared to controls (n = 6, p < 0.05). Importantly, the new composite exhibited no significant difference in antibacterial performance before and after 90-day-aging, demonstrating long-term antibacterial activity (p > 0.1). The LSS antibacterial and remineralizing composite presented a low cell viability at original extract that has increased with further dilutions. In conclusion, this study spotlighted that the new bioactive composite not only had a low shrinkage stress, but also down-regulated the growth of oral biofilms, reduced acid production, maintained antibacterial activity after the 90-day-aging, and did not compromise the cytocompatibility. [ABSTRACT FROM AUTHOR]

Herein, we investigated a biointeractive tooth sealing material consisted of dimethylaminohexadecyl methacrylate (DMAHDM) and amorphous calcium phosphate nanoparticles (NACPs) to address the above issues simultaneously. Of note, 5% DMAHDM was incorporated into the resin blend, and 20% NACP was added to inorganic filler content of dental formulations intended as dental sealants. The sealing materials were used to seal human extracted teeth. The sealed teeth were subjected to an early childhood caries (ECC) key pathogen (Candida albicans and Streptococcus mutans) biofilm model using a dynamic caries tooth model (CDC reactor). The biofilm growth over the sealed teeth was assessed via colony‐forming unit counting metabolic activity assays. The enamel surface hardness loss, degree of conversion, shear bond strength (SBS), and cytotoxicity were also investigated. Formulations having DMAHDM displayed antibacterial efficiency of 2.8–3.5 and 1.4–4.0 log inhibition for Streptococcus mutans and Candida albicans, respectively. Furthermore, the metabolic activity was reduced on the top of the sealed tooth with the biointeractive sealing materials (p <.05). The degree of conversion values was acceptable. The enamel surface hardness loss decreases (36 ± 9.8%) when in contact with the biointeractive tooth sealing material. The SBS of the combined formulation (5% DMAHDM + 20% NACP) was lower than commercial sealant but similar to experimental control. The investigated sealing material holds valuable dual antibacterial and antifungal activities associated with a reduced mineral loss against the cariogenic challenge promoted by ECC key pathogens. [ABSTRACT FROM AUTHOR]

Short-term studies on calcium-phosphate (CaP) ion-rechargeable composites were reported. The long-term rechargeability is important but unknown. The objectives of this study were to investigate nanocomposite with strong antibacterial and ion-recharge capabilities containing dimethylaminododecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP), and evaluate long-term ion-recharge by testing for 12 cycles (taking 6 months to complete) for the first time. Three groups were tested: (1) Heliomolar control; (2) Resin+20%NACP+50%glass; (3) Resin+3%DMAHDM+20%NACP+50%glass. Biofilm acid and colony-forming units (CFU) were measured. Ion-recharge was tested for 12 cycles. NACP-DMAHDM composite reduced biofilm acid, and reduced CFU by 4 logs. High levels of ion releases were maintained throughout 12 cycles of recharge, maintaining steady-state releases without reduction in 6 months (p>0.1), representing long-term remineralization potential. Bioactive nanocomposite demonstrated long-term ion-rechargeability for the first time, showed remineralization and potent anti-biofilm functions, with promise for tooth restorations to combat caries. [ABSTRACT FROM AUTHOR]

The objectives were to develop a novel rechargeable cement containing amorphous calcium-phosphate nanoparticles (nanoACP) to suppress tooth decay. Five cements were made with: (1) 60% glass particles (experimental control); (2) 40% glass+20% nanoACP; (3) 30% glass+30% nanoACP; (4) 20% glass+40% nanoACP; (5) 10% glass+50% nanoACP. Groups 1-4 had enamel bond strengths similar to Transbond XT (3M) and Vitremer (3M) (p>0.1). The nanoACP cement had calcium and phosphate ion release which increased with increasing nanoACP fillers. The recharged cement had substantial ion re-release continuously for 14 days after a single recharge. Ion re-release did not decrease with increasing recharge/re-release cycles. Groups 3-5 maintained a safe pH of medium (>5.5); however, control cements had cariogenic pH of medium (<4.5) due to biofilm acid. Therefore, nanoACP cement (1) had good bond strength to enamel, (2) possessed calcium and phosphate ion recharge/re-release capability, and (3) raised biofilm pH to a safe level to inhibit caries. [ABSTRACT FROM AUTHOR]

Abstract Objective 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. Methods 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. Results Flexural strengths and moduli of CaP-rechargeable composites matched those of a commercial composite without CaP rechargeability (p > 0.1). Adding 1.5% and 3% MPC reduced protein adsorption to 1/3 and 1/5, respectively, that of commercial composite (p < 0.05). 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. Significance 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. [ABSTRACT FROM AUTHOR]

Metformin is an old and widely accepted first-line drug for treating type 2 diabetes. Our previous studies demonstrate that metformin can stimulate the osteo/odontogenic differentiation of human-induced pluripotent stem cell-derived mesenchymal stem cells and human dental pulp cells (DPCs). Due to the rapid dilution of metformin from the defect area, the aim of this study was to develop a drug delivery system with controlled release of metformin to promote cell viability and odontogenic differentiation of DPCs favoring dentin regeneration. Calcium phosphate cement (CPC) containing chitosan and metformin as a scaffold was synthesized. DPCs were seeded onto the scaffold, and the viability and proliferation were evaluated at several time points. For osteogenic differentiation analysis, alkaline phosphatase (ALP) activity was tested, cells were stained with Alizarin Red, and the expression of odontogenic markers was evaluated by real-time polymerase chain reaction. DPCs remained viable and attached well to the CPC-chitosan composite scaffold. Moreover, the addition of metformin to the CPC-chitosan composite did not adversely affect cell proliferation, compared to that of CPC control. Our data further revealed that the novel CPC-chitosan-metformin composite enhanced the odontogenic differentiation of DPCs, as evidenced by higher ALP activity, elevated expression of odontoblastic markers, and strong mineral deposition. These results suggest that the new CPC-chitosan-metformin composite is a highly promising scaffold with the potential for tissue engineering applications including dentin regeneration. [ABSTRACT FROM AUTHOR]

In this study, a novel calcium phosphate cement containing gold nanoparticles (GNP-CPC) was developed. Its osteogenic induction ability on human dental pulp stem cells (hDPSCs) was investigated for the first time. The incorporation of GNPs improved hDPSCs behavior on CPC, including better cell adhesion (about 2-fold increase in cell spreading) and proliferation, and enhanced osteogenic differentiation (about 2–3-fold increase at 14 days). GNPs endow CPC with micro-nano-structure, thus improving surface properties for cell adhesion and subsequent behaviors. In addition, GNPs released from GNP-CPC were internalized by hDPSCs, as verified by transmission electron microscopy (TEM), thus enhancing cell functions. The culture media containing GNPs enhanced the cellular activities of hDPSCs. This result was consistent with and supported the osteogenic induction results of GNP-CPC. In conclusion, GNP-CPC significantly enhanced the osteogenic functions of hDPSCs. GNPs are promising to modify CPC with nanotopography and work as bioactive additives thus enhance bone regeneration. [ABSTRACT FROM AUTHOR]

Enamel demineralization is destructive, esthetically compromised, and costly complications for orthodontic patients. Nano-sized amorphous calcium phosphate (NACP) has been explored to address this challenge. The 20% NACP-loaded ortho-cement notably exhibited favorable behavior on reducing demineralization of enamel around brackets in a caries model designed to simulate the carious attack. The 20% NACP-loaded ortho-cement markedly promotes higher calcium and phosphate release at a low pH, and the mineral loss was almost two fold lower and carious lesion depth decreased the by 1/3. This novel approach is promising co-adjuvant route for prevention of dental caries dissemination in millions of patients under orthodontic treatment. [ABSTRACT FROM PUBLISHER]

Objective Secondary caries is a primary reason for dental restoration failures. The objective of this study was to investigate the remineralization of human dentin lesions in vitro via restorations using nanocomposites containing nanoparticles of amorphous calcium phosphate (NACP) or NACP and tetracalcium phosphate (TTCP) for the first time. Methods NACP was synthesized by a spray-drying technique and incorporated into a resin consisting of ethoxylated bisphenol A dimethacrylate (EBPADMA) and pyromellitic glycerol dimethacrylate (PMGDM). After restoring the dentin lesions with nanocomposites as well as a non-releasing commercial composite control, the specimens were treated with cyclic demineralization (pH 4, 1 h per day) and remineralization (pH 7, 23 h per day) for 4 or 8 weeks. Calcium (Ca) and phosphate (P) ion releases from composites were measured. Dentin lesion remineralization was measured at 4 and 8 weeks by transverse microradiography (TMR). Results Lowering the pH increased ion release of NACP and NACP-TTCP composites. At 56 days, the released Ca concentration in mmol/L (mean ± SD; n = 3) was (13.39 ± 0.72) at pH 4, much higher than (1.19 ± 0.06) at pH 7 (p < 0.05). At 56 days, P ion concentration was (5.59 ± 0.28) at pH 4, much higher than (0.26 ± 0.01) at pH 7 (p < 0.05). Quantitative microradiography showed typical subsurface dentin lesions prior to the cyclic demineralization/remineralization treatment, and dentin remineralization via NACP and NACP-TTCP composites after 4 and 8 weeks of treatment. At 8 weeks, NACP nanocomposite achieved dentin lesion remineralization (mean ± SD; n = 15) of (48.2 ± 11.0)%, much higher than (5.0 ± 7.2)% for dentin in commercial composite group after the same cyclic demineralization/remineralization regimen (p < 0.05). Significance Novel NACP-based nanocomposites were demonstrated to achieve dentin lesion remineralization for the first time. These results, coupled with acid-neutralization and good mechanical properties shown previously, indicate that the NACP-based nanocomposites are promising for restorations to inhibit caries and protect tooth structures. [ABSTRACT FROM AUTHOR]

The objectives of this study were to develop a novel method to remineralize dentin lesions, and investigate the remineralization effects of poly (amido amine) (PAMAM) dendrimer plus a bonding agent with nanoparticles of amorphous calcium phosphate (NACP) in a cyclic artificial saliva/lactic acid environment for the first time. Dentin lesions were produced via phosphoric acid. Four groups were tested: (1) dentin control, (2) dentin with PAMAM, (3) dentin with NACP bonding agent, and (4) dentin with PAMAM plus NACP bonding agent. Specimens were treated with cyclic artificial saliva/lactic acid. The remineralized dentin was examined using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), hardness and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). NACP bonding agent yielded a dentin shear bond strength similar to commercial controls (Prime & Bond NT, Dentsply; Scotchbond Multi-purpose, 3M) ( p > 0.1). Increasing NACP in bonding agent from 0 to 40% did not affect bond strength. NACP bonding agent neutralized the acid and released Ca ions with concentrations of 4 to 20 mmol/L, and P ions of 2 to 9 mmol/L. PAMAM or NACP bonding agent alone achieved slight remineralization. The PAMAM + NACP group achieved the greatest dentin remineralization p < 0.05). At 20 days, PAMAM + NACP increased the hardness of pre-demineralized dentin to reach the normal dentin hardness ( p > 0.1). In conclusion, superior remineralization of PAMAM + NACP bonding agent was demonstrated for the first time. PAMAM + NACP bonding agent induced dentin remineralization under acid challenge, when conventional remineralization methods such as PAMAM alone did not work well. The novel PAMAM + NACP bonding agent method is promising to improve the longevity of resin-dentin bonds, inhibit caries, and protect teeth. [ABSTRACT FROM AUTHOR]

Objectives. The objectives of this study were to: (1) develop a bioactive multifunctional composite (BMC) via nanoparticles of amorphous calcium phosphate (NACP), 2-methacryloyloxyethyl phosphorylcholine (MPC), dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of silver (NAg); and (2) investigate the effects of combined BMC + poly (amido amine) (PAMAM) on remineralization of demineralized root dentin in a cyclic artificial saliva/lactic acid environment for the first time. Methods. Root dentin specimens were prepared and demineralized with 37% phosphoric acid for 15 s. Four groups were prepared: (1) root dentin control; (2) root dentin with BMC; (3) root dentin with PAMAM; (4) root dentin with BMC + PAMAM. Specimens were treated with a cyclic artificial saliva/lactic acid regimen for 21 days. Calcium (Ca) and phosphate (P) ion concentrations and acid neutralization were determined. The remineralized root dentin specimens were examined via hardness testing and scanning electron microscopy (SEM). Results. Mechanical properties of BMC were similar to commercial control composites (p = 0.913). BMC had excellent Ca and P ion release and acid-neutralization capability. BMC or PAMAM alone each achieved slight mineral regeneration in demineralized root dentin. The combined BMC + PAMAM induced the greatest root dentin remineralization, and increased the hardness of pre-demineralized root dentin to match that of healthy root dentin (p = 0.521). Significance. The excellent root dentin remineralization effects of BMC + PAMAM were demonstrated for the first time. BMC + PAMAM induced effective and complete root dentin remineralization in an acid challenge environment. The novel BMC + PAMAM method is promising for Class V and other restorations to remineralize and protect tooth structures. [ABSTRACT FROM AUTHOR]

Objectives The objective of this study was to investigate the effects of poly (amido amine) (PAMAM), composite with nanoparticles of amorphous calcium phosphate (NACP), and the combined PAMAM + NACP nanocomposite treatment, on remineralization of demineralized dentin in a cyclic artificial saliva/lactic acid environment for the first time. Methods Dentin specimens were prepared and demineralized with 37% phosphoric acid for 15 s. Four groups were prepared: (1) dentin control, (2) dentin coated with PAMAM, (3) dentin with NACP composite, (4) dentin with PAMAM + NACP. Specimens were treated with a cyclic artificial saliva/lactic acid regimen for 21 days. Acid neutralization and calcium (Ca) and phosphate (P) ion concentrations were measured. The remineralized dentin specimens were examined by scanning electron microscopy (SEM) and hardness testing. Results NACP nanocomposite had mechanical properties similar to commercial control composites (p > 0.1). NACP composite had acid-neutralization and Ca and P ion release capability. PAMAM or NACP composite each alone achieved remineralization and increased the hardness of demineralized dentin (p < 0.05). PAMAM + NACP nanocomposite achieved the greatest mineral regeneration in demineralized dentin and the greatest hardness increase in demineralized dentin, which approached the hardness of healthy dentin (p > 0.1). Significance The superior remineralization efficacy of PAMAM + NACP was demonstrated for the first time. PAMAM + NACP induced remineralization in demineralized dentin in an acid challenge environment, when conventional remineralization methods such as PAMAM did not work well. The novel PAMAM + NACP composite approach is promising for a wide range of dental applications to inhibit caries and protect tooth structures. [ABSTRACT FROM AUTHOR]

Objectives Calcium phosphate (CaP) composites with Ca and P ion release can remineralize tooth lesions and inhibit caries. But the ion release lasts only a few months. The objectives of this study were to develop rechargeable CaP dental composite for the first time, and investigate the Ca and P recharge and re-release of composites with nanoparticles of amorphous calcium phosphate (NACP) to achieve long-term inhibition of caries. Methods Three NACP nanocomposites were fabricated with resin matrix of: (1) bisphenol A glycidyl dimethacrylate (BisGMA) and triethylene glycol dimethacrylate (TEGDMA) at 1:1 mass ratio (referred to as BT group); (2) pyromellitic glycerol dimethacrylate (PMGDM) and ethoxylated bisphenol A dimethacrylate (EBPADMA) at 1:1 ratio (PE group); (3) BisGMA, TEGDMA, and Bis[2-(methacryloyloxy)ethyl] phosphate (BisMEP) at 2:1:1 ratio (BTM group). Each resin was filled with 20% NACP and 50% glass particles, and the composite was photo-cured. Specimens were tested for flexural strength and elastic modulus, Ca and P ion release, and Ca and P ion recharge and re-release. Results NACP nanocomposites had strengths 3-fold of, and elastic moduli similar to, commercial resin-modified glass ionomer controls. CaP ion recharge capability was the greatest for PE group, followed by BTM group, with BT group being the lowest ( p < 0.05). For each recharge cycle, CaP re-release reached similarly high levels, showing that CaP re-release did not decrease with more recharge cycles. After six recharge/re-release cycles, NACP nanocomposites without further recharge had continuous CaP ion release for 42 d. Significance Novel rechargeable CaP composites achieved long-term and sustained Ca and P ion release. Rechargeable NACP nanocomposite is promising for caries-inhibiting restorations, and the Ca and P ion recharge and re-release method has wide applicability to dental composites, adhesives, cements and sealants to achieve long-term caries-inhibition. [ABSTRACT FROM AUTHOR]

Objectives: Fracture and secondary caries are the primary reasons for dental restoration failure. The objective of this study was to develop a self-healing composite to heal cracks, while containing dimethylaminohexadecyl methacrylate (DMAHDM) for antibacterial function and nanoparticles of amorphous calcium phosphate (NACP) for remineralization. Methods: Microcapsules were synthesized with poly(urea-formaldehyde) (PUF) shells containing triethylene glycol dimethacrylate (TEGDMA) and N,N-dihydroxyethyl-p-toluidine (DHEPT) as healing liquid. Composite contained 20 mass% of NACP and 35% glass fillers. In addition, composite contained 0%, 2.5%, 5%, 7.5%, or 10% of microcapsules. A single edge Vnotched beam method measured fracture toughness (KIC) and self-healing efficiency. A dental plaque microcosm biofilm model was used to test the antibacterial properties. Results: Incorporation of microcapsules up to 7.5% into the composite did not adversely affect the mechanical properties (p > 0.1). Successful self-healing was achieved, with KIC recovery of 65-81% (mean ± sd; n = 6) to regain the load-bearing capability after composite fracture. The self-healing DMAHDM-NACP composite displayed a strong antibacterial potency, inhibiting biofilm viability and lactic acid production, and reducing colony-forming units by 3-4 orders of magnitude, compared to control composite without DMAHDM. Conclusions: A dental composite was developed with triple benefits of self-healing after fracture, antibacterial activity, and remineralization capability for the first time. Clinical significance: The self-healing, antibacterial and remineralizing composite may be promising for tooth cavity restorations to combat bulk fracture and secondary caries. The method of using triple agents (self-healing microcapsules, DMAHDM, and NACP) may have wide applicability to other dental composites, adhesives, sealants and cements. [ABSTRACT FROM AUTHOR]

Human embryonic stem cells (hESCs) are an exciting cell source as they offer an unlimited supply of cells that can differentiate into all cell types for regenerative medicine applications. To date, there has been no report on hESCs with calcium phosphate cement (CPC) scaffolds for bone regeneration in vivo. The objectives of this study were to: (i) investigate hESCs for bone regeneration in vivo in critical-sized cranial defects in rats; and (ii) determine the effects of cell seeding and platelets in macroporous CPC on new bone and blood vessel formation. hESCs were cultured to yield mesenchymal stem cells (MSCs), which underwent osteogenic differentiation. Four groups were tested in rats: (i) CPC control without cells; (ii) CPC with hESC-derived MSCs (CPC + hESC-MSC); (iii) CPC with hESC-MSCs and 30% human platelet concentrate (hPC) (CPC + hESC-MSC + 30% hPC); and (iv) CPC + hESC-MSC + 50% hPC. In vitro, MSCs were derived from embryoid bodies of hESCs. Cells on CPC were differentiated into the osteogenic lineage, with highly elevated alkaline phosphatase and osteocalcin expressions, as well as mineralization. At 12 weeks in vivo, the groups with hESC-MSCs and hPC had three times as much new bone as, and twice the blood vessel density of, the CPC control. The new bone in the defects contained osteocytes and blood vessels, and the new bone front was lined with osteoblasts. The group with 30% hPC and hESC-MSCs had a blood vessel density that was 49% greater than the hESC-MSC group without hPC, likely due to the various growth factors in the platelets enhancing both new bone and blood vessel formation. In conclusion, hESCs are promising for bone tissue engineering, and hPC can enhance new bone and blood vessel formation. Macroporous CPC with hESC-MSCs and hPC may be useful for bone regeneration in craniofacial and orthopedic applications. [ABSTRACT FROM AUTHOR]

Objective Recurrent caries at the margins is a primary reason for restoration failure. The objectives of this study were to develop bonding agent with the double benefits of antibacterial and remineralizing capabilities, to investigate the effects of NACP filler level and solution pH on Ca and P ion release from adhesive, and to examine the antibacterial and dentin bond properties. Methods Nanoparticles of amorphous calcium phosphate (NACP) and a quaternary ammonium monomer (dimethylaminododecyl methacrylate, DMADDM) were synthesized. Scotchbond Multi-Purpose (SBMP) primer and adhesive served as control. DMADDM was incorporated into primer and adhesive at 5% by mass. NACP was incorporated into adhesive at filler mass fractions of 10%, 20%, 30% and 40%. A dental plaque microcosm biofilm model was used to test the antibacterial bonding agents. Calcium (Ca) and phosphate (P) ion releases from the cured adhesive samples were measured vs. filler level and solution pH of 7, 5.5 and 4. Results Adding 5% DMADDM and 10-40% NACP into bonding agent, and water-aging for 28 days, did not affect dentin bond strength, compared to SBMP control at 1 day (p>0.1). Adding DMADDM into bonding agent substantially decreased the biofilm metabolic activity and lactic acid production. Total microorganisms, total streptococci, and mutans streptococci were greatly reduced for bonding agents containing DMADDM. Increasing NACP filler level from 10% to 40% in adhesive increased the Ca and P ion release by an order of magnitude. Decreasing solution pH from 7 to 4 increased the ion release from adhesive by 6-10 folds. Significance Bonding agents containing antibacterial DMADDM and remineralizer NACP were formulated to have Ca and P ion release, which increased with NACP filler level from 10% to 40% in adhesive. NACP adhesive was "smart" and dramatically increased the ion release at cariogenic pH 4, when these ions would be most-needed to inhibit caries. Therefore, bonding agent containing DMADDM and NACP may be promising to inhibit biofilms and remineralize tooth lesions thereby increasing the restoration longevity. [ABSTRACT FROM AUTHOR]

(1) Background: Vascularization remains a critical challenge in bone tissue engineering. The objective of this study was to prevascularize calcium phosphate cement (CPC) scaffold by co-culturing human periodontal ligament stem cells (hPDLSCs) and human umbilical vein endothelial cells (hUVECs) for the first time; (2) Methods: hPDLSCs and/or hUVECs were seeded on CPC scaffolds. Three groups were tested: (i) hUVEC group (hUVECs on CPC); (ii) hPDLSC group (hPDLSCs on CPC); (iii) co-culture group (hPDLSCs + hUVECs on CPC). Osteogenic differentiation, bone mineral synthesis, and microcapillary-like structures were evaluated; (3) Results: Angiogenic gene expressions of co-culture group were 6–9 fold those of monoculture. vWF expression of co-culture group was 3 times lower than hUVEC-monoculture group. Osteogenic expressions of co-culture group were 2–3 folds those of the hPDLSC-monoculture group. ALP activity and bone mineral synthesis of co-culture were much higher than hPDLSC-monoculture group. Co-culture group formed capillary-like structures at 14–21 days. Vessel length and junction numbers increased with time; (4) Conclusions: The hUVECs + hPDLSCs co-culture on CPC scaffold achieved excellent osteogenic and angiogenic capability in vitro for the first time, generating prevascularized networks. The hPDLSCs + hUVECs co-culture had much better osteogenesis and angiogenesis than monoculture. CPC scaffolds prevacularized via hPDLSCs + hUVECs are promising for dental, craniofacial, and orthopedic applications. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: Secondary caries at the restoration margins remains the main reason for failure. Although calcium phosphate (CaP) composites are promising for caries inhibition, there has been no report of CaP composite to inhibit caries in situ. The objectives of this study were to investigate the caries-inhibition effect of nanocomposite containing nanoparticles of amorphous calcium phosphate (NACP) in a human in situ model for the first time, and to determine colony-forming units (CFU) and Ca and P ion concentrations of biofilms on the composite restorations. Methods: NACP with a mean particle size of 116nm were synthesized via a spray-drying technique. Two composites were fabricated: NACP nanocomposite, and control composite filled with glass particles. Twenty-five volunteers wore palatal devices containing bovine enamel slabs with cavities restored with NACP or control composite. After 14 days, the adherent biofilms were collected for analyses. Transverse microradiography determined the enamel mineral profiles at the margins, and the enamel mineral loss ΔZ was measured. Results: NACP nanocomposite released Ca and P ions and the release significantly increased at cariogenic low pH (p <0.05). Biofilms on NACP nanocomposite contained higher Ca (p =0.007) and P ions (p =0.005) than those of control (n =25). There was no significant difference in biofilm CFU between the two composites (p >0.1). Microradiographs showed typical subsurface lesions in enamel next to control composite, but much less lesion around NACP nanocomposite. Enamel mineral loss ΔZ (mean±sd; n =25) around NACP nanocomposite was 13.8±9.3μm, much less than 33.5±19.0μm of the control (p =0.001). Significance: Novel NACP nanocomposite substantially reduced caries formation in a human in situ model for the first time. Enamel mineral loss at the margins around NACP nanocomposite was less than half of the mineral loss around control composite. Therefore, the Ca and P ion-releasing NACP nanocomposite is promising for caries-inhibiting restorations. [Copyright &y& Elsevier]

Abstract: The need for bone repair has increased as the population ages. The objectives of this study were to (1) develop a novel biofunctionalized and macroporous calcium phosphate cement (CPC) containing alginate–fibrin microbeads encapsulating human umbilical cord mesenchymal stem cells (hUCMSC) and, for the first time, (2) investigate hUCMSC proliferation and osteogenic differentiation inside the CPC. A macroporous CPC was developed using calcium phosphate powder, chitosan, and a gas-foaming porogen. Five types of CPC were fabricated: a CPC control, CPC+0.05% fibronectin (Fn), CPC+0.1% Fn, CPC+0.1% arginine–glycine–aspartate (RGD), and CPC+0.1% Fn+0.1% RGD. Alginate–fibrin microbeads containing 106 hUCMSC per ml were encapsulated in the CPC paste. After the CPC had set, the degradable microbeads released hUCMSC within it. The hUCMSC proliferated inside the CPC, with the cell density after 21days being 4-fold that on day1. CPC+0.1% RGD had the highest cell density, which was 4-fold that of the CPC control. The released cells differentiated along the osteogenic lineage and synthesized bone mineral. The hUCMSC inside the CPC+0.1% RGD construct expressed the genes alkaline phosphatase, osteocalcin and collagen I, at twice the level of the CPC control. Mineral synthesis by hUCMSC inside the CPC+0.1% RGD construct was 2-fold that in the CPC control. RGD and Fn incorporation in the CPC did not compromise its strength, which matched the reported strength of cancellous bone. In conclusion, degradable microbeads released hUCMSC which proliferated, differentiated and synthesized minerals inside the macroporous CPC. The CPC with RGD greatly enhanced cell function. The novel biofunctionalized and macroporous CPC–microbead–hUCMSC construct is promising for bone tissue engineering applications. [Copyright &y& Elsevier]

Abstract: Objectives: Previous studies have developed calcium phosphate and fluoride releasing composites. Other studies have incorporated chlorhexidine (CHX) particles into dental composites. However, CHX has not been incorporated in calcium phosphate and fluoride composites. The objectives of this study were to develop nanocomposites containing amorphous calcium phosphate (ACP) or calcium fluoride (CaF2) nanoparticles and CHX particles, and investigate Streptococcus mutans biofilm formation and lactic acid production for the first time. Methods: Chlorhexidine was frozen via liquid nitrogen and ground to obtain a particle size of 0.62μm. Four nanocomposites were fabricated with fillers of: nano ACP; nano ACP+10% CHX; nano CaF2; nano CaF2 +10% CHX. Three commercial materials were tested as controls: a resin-modified glass ionomer, and two composites. S. mutans live/dead assay, colony-forming unit (CFU) counts, biofilm metabolic activity, and lactic acid were measured. Results: Adding CHX fillers to ACP and CaF2 nanocomposites greatly increased their antimicrobial capability. ACP and CaF2 nanocomposites with CHX that were inoculated with S. mutans had a growth medium pH>6.5 after 3 d, while the control commercial composites had a cariogenic pH of 4.2. Nanocomposites with CHX reduced the biofilm metabolic activity by 10–20 folds and reduced the acid production, compared to the controls. CFU on nanocomposites with CHX were three orders of magnitude less than that on commercial composite. Mechanical properties of nanocomposites with CHX matched a commercial composite without fluoride. Significance: The novel calcium phosphate and fluoride nanocomposites could be rendered antibacterial with CHX to greatly reduce biofilm formation, acid production, CFU and metabolic activity. The antimicrobial and remineralizing nanocomposites with good mechanical properties may be promising for a wide range of tooth restorations with anti-caries capabilities. [Copyright &y& Elsevier]

Abstract: Objectives: Calcium and phosphate ion-releasing resin composites are promising for remineralization. However, there has been no report on incorporating antibacterial agents to these composites. The objective of this study was to develop antibacterial and mechanically strong nanocomposites incorporating a quaternary ammonium dimethacrylate (QADM), nanoparticles of silver (NAg), and nanoparticles of amorphous calcium phosphate (NACP). Methods: The QADM, bis(2-methacryloyloxyethyl) dimethylammonium bromide (ionic dimethacrylate-1), was synthesized from 2-(N,N-dimethylamino)ethyl methacrylate and 2-bromoethyl methacrylate. NAg was synthesized by dissolving Ag 2-ethylhexanoate salt in 2-(tert-butylamino)ethyl methacrylate. Mechanical properties were measured in three-point flexure with bars of 2mm×2mm×25mm (n =6). Composite disks (diameter=9mm, thickness=2mm) were inoculated with Streptococcus mutans. The metabolic activity and lactic acid production of biofilms were measured (n =6). Two commercial composites were used as controls. Results: Flexural strength and elastic modulus of NACP+QADM, NACP+NAg, and NACP+QADM+NAg matched those of commercial composites with no antibacterial property (p >0.1). The NACP+QADM+NAg composite decreased the titer counts of adherent S. mutans biofilms by an order of magnitude, compared to the commercial composites (p <0.05). The metabolic activity and lactic acid production of biofilms on NACP+QADM+NAg composite were much less than those on commercial composites (p <0.05). Combining QADM and NAg rendered the nanocomposite more strongly antibacterial than either agent alone (p <0.05). Significance: QADM and NAg were incorporated into calcium phosphate composite for the first time. NACP+QADM+NAg was strongly antibacterial and greatly reduced the titer counts, metabolic activity, and acid production of S. mutans biofilms, while possessing mechanical properties similar to commercial composites. These nanocomposites are promising to have the double benefits of remineralization and antibacterial capabilities to inhibit dental caries. [Copyright &y& Elsevier]

Abstract: Fibrous scaffolds are promising for tissue engineering because of the high surface area and fibrous features mimicking the extracellular matrix in vivo. Calcium phosphate cements (CPCs) can be injected and self-set in the bone defect. A literature search revealed that there have been no reports on stem cell seeding on CPC containing electrospun submicron fibers. The objective of this study was to investigate for the first time the effects of electrospun fibers in CPC on mechanical properties and human umbilical cord mesenchymal stem cell (hUCMSC) proliferation, osteogenic differentiation and mineralization. Poly(d,l-lactide-co-glycolide) fibers were made via an electrospinning technique to yield an average fiber diameter of 650nm. The fibers were incorporated into CPC consisting of tetracalcium phosphate, dicalcium phosphate anhydrous and chitosan lactate. Fiber volume fractions were 0%, 2.5%, 5% and 10%. CPC with 10% fibers had a flexural strength that was twice that of CPC without fibers, and a work-of-fracture (toughness) that was an order of magnitude larger than that of CPC without fibers. hUCMSCs proliferated rapidly and synthesized bone minerals when attached to the electrospun fiber–CPC scaffolds. Alkaline phosphatase, osteocalcin and collagen I expressions of hUCMSCs were doubled, while mineralization was increased by 40%, when fiber volume fraction in CPC was increased from 0% to 10%. The enhanced cell function was attributed to the high surface area and biomimetic features of the fiber–CPC scaffold. In conclusion, incorporating submicron fibers into CPC greatly improved the strength and toughness of the CPC. Creating submicron fibrous features in CPC was a useful method for enhancing the osteogenic differentiation and mineralization of stem cells. The novel electrospun fiber–CPC–hUCMSC construct is promising for stem cell delivery and bone tissue engineering. [Copyright &y& Elsevier]

Abstract: Due to its injectability and excellent osteoconductivity, calcium phosphate cement (CPC) is highly promising for orthopedic applications. However, a literature search revealed no report on human bone marrow mesenchymal stem cell (hBMSC) encapsulation in CPC for bone tissue engineering. The aim of this study was to encapsulate hBMSCs in alginate hydrogel beads and then incorporate them into CPC, CPC–chitosan and CPC–chitosan–fiber scaffolds. Chitosan and degradable fibers were used to mechanically reinforce the scaffolds. After 21days, that the percentage of live cells and the cell density of hBMSCs inside CPC-based constructs matched those in alginate without CPC, indicating that the CPC setting reaction did not harm the hBMSCs. Alkaline phosphate activity increased by 8-fold after 14days. Mineral staining, scanning electron microscopy and X-ray diffraction confirmed that apatitic mineral was deposited by the cells. The amount of hBMSC-synthesized mineral in CPC–chitosan–fiber matched that in CPC without chitosan and fibers. Hence, adding chitosan and fibers, which reinforced the CPC, did not compromise hBMSC osteodifferentiation and mineral synthesis. In conclusion, hBMSCs were encapsulated in CPC and CPC–chitosan–fiber scaffolds for the first time. The encapsulated cells remained viable, osteodifferentiated and synthesized bone minerals. These self-setting, hBMSC-encapsulating CPC-based constructs may be promising for bone tissue engineering applications. [ABSTRACT FROM AUTHOR]

Abstract: The need for bone repair has increased as the population ages. Stem cell-scaffold approaches hold immense promise for bone tissue engineering. However, currently, preformed scaffolds for cell delivery have drawbacks including the difficulty to seed cells deep into the scaffold, and inability for injection in minimally-invasive surgeries. Current injectable polymeric carriers and hydrogels are too weak for load-bearing orthopedic applications. The objective of this study was to develop an injectable and mechanically-strong stem cell construct for bone tissue engineering. Calcium phosphate cement (CPC) paste was combined with hydrogel microbeads encapsulating human umbilical cord mesenchymal stem cells (hUCMSCs). The hUCMSC-encapsulating composite paste was fully injectable under small injection forces. Cell viability after injection matched that in hydrogel without CPC and without injection. Mechanical properties of the construct matched the reported values of cancellous bone, and were much higher than previous injectable polymeric and hydrogel carriers. hUCMSCs in the injectable constructs osteodifferentiated, yielding high alkaline phosphatase, osteocalcin, collagen type I, and osterix gene expressions at 7 d, which were 50–70 fold higher than those at 1 d. Mineralization by the hUCMSCs at 14 d was 100-fold that at 1 d. In conclusion, a fully injectable, mechanically-strong, stem cell–CPC scaffold construct was developed. The encapsulated hUCMSCs remained viable, osteodifferentiated, and synthesized bone minerals. The new injectable stem cell construct with load-bearing capability may enhance bone regeneration in minimally-invasive and other orthopedic surgeries. [Copyright &y& Elsevier]

Abstract: Human bone marrow mesenchymal stem cells (hBMSCs) require an invasive procedure to harvest, and have lower self-renewal potential with aging. Umbilical cord mesenchymal stem cells (hUCMSCs) are a relatively new stem cell source; this study reveals a self-setting and load-bearing calcium phosphate construct that encapsulates these stem cells. The flexural strength (mean±sd; n =5) of the hUCMSC-encapsulating calcium phosphate cement (CPC) increased from (3.5±1.1) MPa without polyglactin fibers, to (11.7±2.1) MPa with 20% of polyglactin fibers (p <0.05). hUCMSCs attached to the bone mineral-mimicking scaffold in the osteogenic media and differentiated down the osteogenic lineage, yielding elevated alkaline phosphatase (ALP) and osteocalcin (OC) gene expressions. ALP and OC on the CPC-fiber scaffold was 2-fold those on CPC control without fibers. hUCMSCs encapsulated inside the scaffolds retained excellent viability and cell density. The encapsulated hUCMSCs inside four different constructs successfully differentiated down the osteogenic lineage and synthesized bone minerals, as confirmed by mineral staining, SEM, and XRD. The percentage of mineral area synthesized by the encapsulated hUCMSCs increased from about 3% at day-7, to 12% at day-21 (p <0.05). In conclusion, this study demonstrated that hUCMSCs encapsulated in the bioengineered scaffolds osteo-differentiated and synthesized bone minerals. The self-setting CPC–chitosan–fiber scaffold supported the viability and osteogenic differentiation of the encapsulated hUCMSCs, and had mechanical strength matching that of cancellous bone. [Copyright &y& Elsevier]

Because of its moldability and excellent osteoconductivity, calcium phosphate cement (CPC) is highly promising for craniofacial and orthopedic applications. The objectives of this study were to investigate the response of human mesenchymal stem cells (hMSCs) to a high‐strength CPC‐chitosan scaffold and to examine cell proliferation and osteogenic differentiation. hMSCs were seeded onto CPC‐chitosan composite, CPC control, and tissue culture polystyrene (TCPS). Alkaline phosphatase activity (ALP) and mineralization of hMSCs were measured. CPC‐chitosan had a flexural strength (mean ± SD; n = 5) of (19.5 ± 1.4) MPa, higher than (8.0 ± 1.4) MPa of CPC control (p < 0.05). The percentage of live hMSCs on CPC‐chitosan was (90.5 ± 1.3)% at 8 days, matching (90.7 ± 3.8)% of CPC control (p > 0.1). The CPC‐chitosan surface area covered by the attached hMSCs increased from (51 ± 11)% at 1 day to (90 ± 4)% at 8 days (p < 0.05), matching those of CPC control (p > 0.1). Hence, the CPC strength was significantly increased via chitosan without compromising the hMSC response. At 8 days, there was a significant increase in ALP of cells in osteogenic media (10.99 ± 0.93) [(mM pNpp/min)/(μg DNA)] versus control media (3.62 ± 0.40) (p < 0.05). hMSCs in osteogenic media exhibited greater mineralization area of (47.5 ± 19.7)% compared with (6.1 ± 2.3)% in control medium on TCPS (p < 0.05). In conclusion, hMSCs showed excellent attachment and viability on the strong and tough CPC‐chitosan scaffold, matching the hMSC response on CPC control. hMSCs were successfully differentiated down the osteogenic lineage. Hence, the strong, in situ hardening CPC‐chitosan scaffold may be useful as a moderate load‐bearing vehicle to deliver hMSCs for maxillofacial and orthopedic bone tissue engineering. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010 [ABSTRACT FROM AUTHOR]

Abstract: Calcium phosphate cement (CPC) can be molded and self-hardens in vivo to form resorbable hydroxyapatite with excellent osteoconductivity. The objective of this study was to develop an injectable, macroporous and strong CPC, and to investigate the effects of porogen and absorbable fibers. Water-soluble mannitol was used as porogen and mixed with CPC at mass fractions from 0% to 50%. CPC with 0–40% mannitol was fully extruded under a syringe force of 10 n. The paste with 50% mannitol required a 100-N force which extruded only 66% of the paste. At fiber volume fraction of 0–5%, the paste was completely extruded. However, at 6% and 7.5% fibers, some fibers were left in the syringe after the paste was extruded. The injectable CPC scaffold had a flexural strength (mean±sd; ) of (3.2±1.0) MPa, which approached the reported strengths for sintered porous hydroxyapatite implants and cancellous bone. In summary, the injectability of a ceramic scaffold, a macroporous CPC, was studies for the first time. Processing parameters were tailored to achieve high injectability, macroporosity, and strength. The injectable and strong CPC scaffold may be useful in surgical sites that are not freely accessible by open surgery or when using minimally invasive techniques. [Copyright &y& Elsevier]

Oral biofilm accumulation at the tooth–restoration interface often leads to recurrent dental caries and restoration failure. The objectives of this study were to: (1) develop a novel bioactive crown cement containing dimethylaminohexadecyl methacrylate (DMAHDM) and nano-sized amorphous calcium phosphate (NACP), and (2) investigate the mechanical properties, anti-biofilm activity, and calcium (Ca2+) and phosphate (PO43−) ion release of the crown cement for the first time. The cement matrix consisted of pyromellitic glycerol dimethacrylate and ethoxylated bisphenol-A dimethacrylate monomers and was denoted PEHB resin matrix. The following cements were tested: (1) RelyX luting cement (commercial control); (2) 55% PEHB + 45% glass fillers (experimental control); (3) 55% PEHB + 20% glass + 25% NACP + 0% DMAHDM; (4) 52% PEHB + 20% glass + 25% NACP + 3% DMAHDM; (5) 51% PEHB + 20% glass + 25% NACP + 4% DMAHDM; (6) 50% PEHB + 20% glass + 25% NACP + 5% DMAHDM. Mechanical properties and ion release were measured. Streptococcusmutans (S. mutans) biofilms were grown on cements, and colony-forming units (CFUs) and other biofilm properties were measured. The novel bioactive cement demonstrated strong antibacterial properties and high levels of Ca2+ and PO43− ion release to remineralize tooth lesions. Adding NACP and DMAHDM into the cement did not adversely affect the mechanical properties and dentin bonding strength. In conclusion, the novel NACP + DMAHDM crown cement has excellent potential for restoration cementation to inhibit caries by suppressing oral biofilm growth and increasing remineralization via Ca2+ and PO43− ions. The NACP + DMAHDM composition may have wide applicability to other biomaterials to promote hard-tissue formation and combat bacterial infection. [ABSTRACT FROM AUTHOR]

Secondary caries often occurs at the tooth-composite margins. This study developed a novel bioactive composite containing DMAHDM (dimethylaminohexadecyl methacrylate) and NACP (nanoparticles of amorphous calcium phosphate), inhibiting caries at the enamel restoration margins in an in vitro saliva-derived biofilm secondary caries model for the first time. Four composites were tested: (1) Heliomolar nanocomposite, (2) 0% DMAHDM + 0% NACP, (3) 3% DMAHDM + 0% NACP, (D) 3% DMAHDM + 30% NACP. Saliva-derived biofilms were tested for antibacterial effects of the composites. Bovine enamel restorations were cultured with biofilms, Ca and P ion release of nanocomposite and enamel hardness at the enamel restoration margins was measured. Incorporation of DMAHDM and NACP into composite did not affect the mechanical properties (p > 0.05). The biofilms' CFU (colony-forming units) were reduced by 2 logs via DMAHDM (p < 0.05). Ca and P ion release of the nanocomposite was increased at cariogenic low pH. Enamel hardness at the margins for DMAHDM group was 25% higher than control (p < 0.05). With DMAHDM + NACP, the enamel hardness was the greatest and about 50% higher than control (p < 0.05). Therefore, the novel composite containing DMAHDM and NACP was strongly antibacterial and inhibited enamel demineralization, resulting in enamel hardness at the margins under biofilms that approached the hardness of healthy enamel. [ABSTRACT FROM AUTHOR]

The objectives of this study were to incorporate iron oxide nanoparticles (IONPs) into calcium phosphate cement (CPC) to enhance bone engineering, and to investigate the effects of IONPs as a liquid or powder on stem cells using IONP-CPC scaffold for the first time. IONP-CPCs were prepared by adding 1% IONPs as liquid or powder. Human dental pulp stem cells (hDPSCs) were seeded. Subcutaneous implantation in mice was investigated. IONP-CPCs had better cell spreading, and greater ALP activity and bone mineral synthesis, than CPC control. Subcutaneous implantation for 6 weeks showed good biocompatibility for all groups. In conclusion, incorporating IONPs in liquid or powder form both substantially enhanced hDPSCs on IONP-CPC scaffold and exhibited excellent biocompatibility. IONP incorporation as a liquid was better than IONP powder in promoting osteogenic differentiation of hDPSCs. Incorporating IONPs and chitosan lactate together in CPC enhanced osteogenesis of hDPSCs more than using either alone. Iron oxide nanoparticles (IONPs) which can be incorporated as liquid or powder can enhance the bioactivity of calcium phosphate cements (CPCs). However, incorporation methods can affect the bioactivity of the final IONP-CPC. Although both methods can result in substantially enhancement of CPCs, incorporation as liquid seemed better than powder in promoting bioactivity. And incorporating IONPs and chitosan lactate together enhanced CPCs better than using either alone. The effects were attributed to the chemical composition, the distribution of IONPs, the scaffold surface properties, and the magnetism effects. Therefore, incorporation methods can affect the bioactivity of IONP-CPC. Suitable incorporation method is promising to achieve better osteogenesis effects. Unlabelled Image [ABSTRACT FROM AUTHOR]

Dental sealants with antibacterial and remineralizing properties are promising for caries prevention among children and adolescents. The application of nanotechnology and polymer development have enabled nanoparticles of amorphous calcium phosphate (NACP) and dimethylaminohexadecyl methacrylate (DMAHDM) to emerge as anti-caries strategies via resin-based dental materials. Our objectives in this study were to (1) incorporate different mass fractions of NACP into a parental rechargeable and antibacterial sealant; (2) investigate the effects on mechanical performance, and (3) assess how the variations in NACP concentration would affect the calcium (Ca) and phosphate (PO4) ion release and re-chargeability over time. NACP were synthesized using a spray-drying technique and incorporated at mass fractions of 0, 10, 20 and 30%. Flexural strength, flexural modulus, and flowability were assessed for mechanical and physical performance. Ca and PO4 ion release were measured over 70 days, and three ion recharging cycles were performed for re-chargeability. The impact of the loading percentage of NACP upon the sealant's performance was evaluated, and the optimized formulation was eventually selected. The experimental sealant at 20% NACP had flexural strength and flexural modulus of 79.5 ± 8.4 MPa and 4.2 ± 0.4 GPa, respectively, while the flexural strength and flexural modulus of a commercial sealant control were 70.7 ± 5.5 MPa (p > 0.05) and 3.3 ± 0.5 GPa (p < 0.05), respectively. A significant reduction in flow was observed in the experimental sealant at 30% NACP (p < 0.05). Increasing the NACP mass fraction increased the ion release. The sealant formulation with NACP at 20% displayed desirable mechanical performance and ideal flow and handling properties, and also showed high levels of long-term Ca and PO4 ion release and excellent recharge capabilities. The findings provide fundamental data for the development of a new generation of antibacterial and rechargeable Ca and PO4 dental sealants to promote remineralization and inhibit caries. [ABSTRACT FROM AUTHOR]

Injectable and self-setting calcium phosphate cement scaffold (CPC) capable of encapsulating and delivering stem cells and bioactive agents would be highly beneficial for dental and craniofacial repairs. The objectives of this study were to: (1) develop a novel injectable CPC scaffold encapsulating human periodontal ligament stem cells (hPDLSCs) and metformin (Met) for bone engineering; (2) test bone regeneration efficacy in vitro and in vivo. hPDLSCs were encapsulated in degradable alginate fibers, which were then mixed into CPC paste. Five groups were tested: (1) CPC control; (2) CPC + hPDLSC-fibers + 0% Met (CPC + hPDLSCs + 0%Met); (3) CPC + hPDLSC-fibers + 0.1% Met (CPC + hPDLSCs + 0.1%Met); (4) CPC + hPDLSC-fibers + 0.2% Met (CPC + hPDLSCs + 0.2%Met); (5) CPC + hPDLSC-fibers + 0.4% Met (CPC + hPDLSCs + 0.4%Met). The injectability, mechanical properties, metformin release, and hPDLSC osteogenic differentiation and bone mineral were determined in vitro. A rat cranial defect model was used to evaluate new bone formation. The novel construct had good injectability and physical properties. Alginate fibers degraded in 7 days and released hPDLSCs, with 5-fold increase of proliferation (p＜0.05). The ALP activity and mineral synthesis of hPDLSCs were increased by Met delivery (p＜0.05). Among all groups, CPC+hPDLSCs+ 0.1%Met showed the greatest cell mineralization and osteogenesis, which were 1.5–10 folds those without Met (p＜0.05). Compared to CPC control, CPC+hPDLSCs+ 0.1%Met enhanced bone regeneration in rats by 9 folds, and increased vascularization by 3 folds (p＜0.05). The novel injectable construct with hPDLSC and Met encapsulation demonstrated excellent efficacy for bone regeneration and vascularization in vivo in an animal model. CPC+hPDLSCs+ 0.1%Met is highly promising for dental and craniofacial applications. • We developed a novel injectable and mechanically strong CPC-alginate hydrogel-hPDLSC scaffold with different dosages of metformin for bone tissue engineering. • The novel construct had much greater bone regeneration and vascularization potency than control in vitro and in vivo. [ABSTRACT FROM AUTHOR]

Objectives: Calcium phosphate cement (CPC) is promising for dental and craniofacial applications due to its ability to be injected or filled into complex-shaped bone defects and molded for esthetics, and its resorbability and replacement by new bone. The objective of this study was to investigate bone regeneration via novel macroporous CPC containing absorbable fibers, hydrogel microbeads and growth factors in critical-sized cranial defects in rats. Methods: Mannitol porogen and alginate hydrogel microbeads were incorporated into CPC. Absorbable fibers were used to provide mechanical reinforcement to CPC scaffolds. Six CPC groups were tested in rats: (1) control CPC without macropores and microbeads; (2) macroporous CPC+large fiber; (3) macroporous CPC+large fiber+nanofiber; (4) same as (3), but with rhBMP2 in CPC matrix; (5) same as (3), but with rhBMP2 in CPC matrix+rhTGF-β1 in microbeads; (6) same as (3), but with rhBMP2 in CPC matrix+VEGF in microbeads. Rats were sacrificed at 4 and 24 weeks for histological and micro-CT analyses. Results: The macroporous CPC scaffolds containing porogen, absorbable fibers and hydrogel microbeads had mechanical properties similar to cancellous bone. At 4 weeks, the new bone area fraction (mean±sd; n =5) in CPC control group was the lowest at (14.8±3.3)%, and that of group 6 (rhBMP2+VEGF) was (31.0±13.8)% (p <0.05). At 24 weeks, group 4 (rhBMP2) had the most new bone of (38.8±15.6)%, higher than (12.7±5.3)% of CPC control (p <0.05). Micro-CT revealed nearly complete bridging of the critical-sized defects with new bone for several macroporous CPC groups, compared to much less new bone formation for CPC control. Significance: Macroporous CPC scaffolds containing porogen, fibers and microbeads with growth factors were investigated in rat cranial defects for the first time. Macroporous CPCs had new bone up to 2-fold that of traditional CPC control at 4 weeks, and 3-fold that of traditional CPC at 24 weeks, and hence may be useful for dental, craniofacial and orthopedic applications. [ABSTRACT FROM AUTHOR]

Objective Patients with dry mouth often have an acidic oral environment lacking saliva that provides calcium (Ca) and phosphate (P) ions. However, there has been no study on dentin remineralization by placing samples in an acidic solution without Ca and P ions. Previous studies used saliva-like solutions with neutral pH and Ca and P ions. Therefore, the objective of this study was to investigate a novel method of combining poly(amido amine) (PAMAM) with a composite of nanoparticles of amorphous calcium phosphate (NACP) on dentin remineralization in an acidic solution without Ca and P ions for the first time. Methods Demineralized dentin specimens were tested into four groups: (1) dentin control, (2) dentin coated with PAMAM, (3) dentin with NACP nanocomposite, (4) dentin with PAMAM plus NACP composite. Specimens were treated with lactic acid at pH 4 without initial Ca and P ions for 21 days. Acid neutralization and Ca and P ion concentrations were measured. Dentin specimens were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and hardness testing vs. remineralization efficacy. Results NACP composite had mechanical properties similar to commercial control composites (p > 0.1). NACP composite neutralized acid and released Ca and P ions. PAMAM alone failed to induce dentin remineralization. NACP alone achieved mild remineralization and slightly increased dentin hardness at 21 days (p > 0.1). In contrast, the PAMAM + NACP nanocomposite method in acid solution without initial Ca and P ions greatly remineralized the pre-demineralized dentin, restoring its hardness to approach that of healthy dentin (p > 0.1). Significance Dentin remineralization via PAMAM + NACP in pH 4 acid without initial Ca and P ions was demonstrated for the first time, when conventional methods such as PAMAM did not work. The novel PAMAM + NACP nanocomposite method is promising to protect tooth structures, especially for patients with reduced saliva to inhibit caries. [ABSTRACT FROM AUTHOR]

The cariogenic biofilm on enamel, restoration, and bonding interface is closely related to dental caries and composite restoration failure. Enamel remineralization at adhesive interface is conducive to protecting bonding interface and inhibiting secondary caries. This study intended to assess the remineralization efficiency of adhesive with dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP) on initial caries lesion of biofilm-coated enamel. Artificial initial carious lesion was created via 72-hour immersion in demineralization solution and cariogenic biofilm was formed after 24-hour culture of Streptococcus mutans (S. mutans). Specimens were then divided into 4 groups: enamel control, enamel treated with NACP, DMAHDM and NACP+DMAHDM respectively. Samples next underwent 7-day cycling, 4 h in BHIS (brain heart infusion broth containing 1 % sucrose) and 20 h in AS (artificial saliva) per day. The pH of BHIS was tested daily. So did the concentration of calcium and phosphate in BHIS and AS. Live/dead staining, colony-forming unit (CFU) count, and lactic acid production of biofilms were measured 7 days later. The enamel remineralization efficiency was evaluated by microhardness testing and transverse microradiography (TMR) quantitatively. Enamel of NACP+DMAHDM group demonstrated excellent remineralization effectiveness. And the NACP+DMAHDM adhesive released a great number of Ca2+ and PO 4 3- ions, increased pH to 5.81 via acid neutralization, decreased production of lactic acid, and reduced CFU count of S. mutans (P < 0.05). The NACP+DMAHDM adhesive would be applicable to preventing secondary caries, strengthening enamel-adhesive interface, and extending the lifespan of composite restoration. [ABSTRACT FROM AUTHOR]

Objectives Calcium phosphate cements (CPCs) are promising for dental and craniofacial repairs. The objectives of this study were to: (1) develop an injectable cell delivery system based on encapsulation of induced pluripotent stem cell-derived mesenchymal stem cells (iPSMSCs) in microbeads; (2) develop a novel tissue engineered construct by dispersing iPSMSC-microbeads in CPC to investigate bone regeneration in an animal model for the first time. Methods iPSMSCs were pre-osteoinduced for 2 weeks (OS-iPSMSCs), or transduced with bone morphogenetic protein-2 (BMP2-iPSMSCs). Cells were encapsulated in fast-degradable alginate microbeads. Microbeads were mixed with CPC paste and filled into cranial defects in nude rats. Four groups were tested: (1) CPC-microbeads without cells (CPC control); (2) CPC-microbeads-iPSMSCs (CPC-iPSMSCs); (3) CPC-microbeads-OS-iPSMSCs (CPC-OS-iPSMSCs); (4) CPC-microbeads-BMP2-iPSMSCs (CPC-BMP2-iPSMSCs). Results Cells maintained good viability inside microbeads after injection. The microbeads were able to release the cells which had more than 10-fold increase in live cell density from 1 to 14 days. The cells exhibited up-regulation of osteogenic markers and deposition of minerals. In vivo , new bone area fraction (mean ± SD; n = 5) for CPC-iPSMSCs group was (22.5 ± 7.6)%. New bone area fractions were (38.9 ± 18.4)% and (44.7 ± 22.8)% for CPC-OS-iPSMSCs group and CPC-BMP2-iPSMSCs group, respectively, 2–3 times the (15.6 ± 11.2)% in CPC control at 12 weeks ( p < 0.05). Cell-CPC constructs accelerated scaffold resorption, with CPC-BMP2-iPSMSCs having remaining scaffold material that was 7-fold less than CPC control. Significance Novel injectable CPC-microbead-cell constructs promoted bone regeneration, with OS-iPSMSCs and BMP2-iPSMSCs having 2–3 fold the new bone of CPC control. Cell delivery accelerated scaffold resorption, with CPC-BMP2-iPSMSC having remaining scaffold material that was 7-fold less than CPC control. Therefore, CPC-microbead-iPSMSC is a promising injectable material for orthopedic, dental and craniofacial bone regenerations. [ABSTRACT FROM AUTHOR]

The objectives of this study were to: (1) develop a multifunctional adhesive via dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP); and (2) investigate its ability to provide metalloproteinases (MMPs) deactivation and remineralization for long-term dentin bonding durability. DMAHDM and NACP were incorporated into Adper™ Single Bond 2 Adhesive (SB2) at mass fractions of 5% and 20%, respectively. Degree of conversion and contact angle were measured. Endogenous MMP activity of the demineralized dentin beams, Masson's trichrome staining, nano-indentation, microtensile bond strength and interfacial nanoleakage analyses were investigated after 24 h and 3 months of storage aging in artificial saliva. Adding DMAHDM and NACP did not compromise the degree of conversion and contact angle of SB2 (p > 0.05). DMAHDM and NACP incorporation reduced the endogenous MMP activity by 53 %, facilitated remineralization, and increased the Young's modulus of hybrid layer by 49 % after 3 months of aging in artificial saliva, compared to control. For SB2 Control, the dentin bond strength decreased by 38 %, with greater nanoleakage expression, after 3 months of aging (p < 0.05). However, DMAHDM+NACP group showed no loss in bond strength, with much less nanoleakage, after 3 months of aging (p > 0.05). DMAHDM+NACP adhesive greatly reduced MMP-degradation activity in demineralized dentin, induced remineralization at adhesive-dentin interface, and maintained the dentin bond strength after aging, without adversely affecting polymerization and dentin wettability. This new adhesive has great potential to help eliminate secondary caries, prevent hybrid layer degradation, and increase the resin-dentin bond longevity. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: Calcium phosphate cement (CPC) is promising for dental and craniofacial repairs. Vascularization in bone tissue engineering constructs is currently a major challenge. The objectives of this study were to investigate the prevascularization of macroporous CPC via coculturing human umbilical vein endothelial cells (HUVEC) and human osteoblasts (HOB), and determine the effect of RGD in CPC on microcapillary formation for the first time. Methods: Macroporous CPC scaffold was prepared using CPC powder, chitosan liquid and gas-foaming porogen. Chitosan was grafted with Arg-Gly-Asp (RGD) to biofunctionalize the CPC. HUVEC and HOB were cocultured on macroporous CPC-RGD and CPC control without RGD for up to 42d. The osteogenic and angiogenic differentiation, bone matrix mineral synthesis, and formation of microcapillary-like structures were measured. Results: RGD-grafting in CPC increased the gene expressions of osteogenic and angiogenic differentiation markers than those of CPC control without RGD. Cell-synthesized bone mineral content also increased on CPC-RGD, compared to CPC control (p <0.05). Immunostaining with endothelial marker showed that the amount of microcapillary-like structures on CPC scaffolds increased with time. At 42d, the cumulative vessel length for CPC-RGD scaffold was 1.69-fold that of CPC control. SEM examination confirmed the morphology of self-assembled microcapillary-like structures on CPC scaffolds. Significance: HUVEC+HOB coculture on macroporous CPC scaffold successfully achieved prevascularization. RGD incorporation in CPC enhanced osteogenic differentiation, bone mineral synthesis, and microcapillary-like structure formation. The novel prevascularized CPC-RGD constructs are promising for dental, craniofacial and orthopedic applications. [Copyright &y& Elsevier]

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 (P > 0.05). 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 (P < 0.05). 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 (P < 0.05). 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. [ABSTRACT FROM AUTHOR]

Calcium phosphate cements (CPCs) mimic nanostructured bone minerals and are promising for dental, craniofacial and orthopedic applications. Vascularization plays a critical role in bone regeneration. This article represents the first review on cutting-edge research on prevascularization of CPC scaffolds to enhance bone regeneration. This article first presented the prevascularization of CPC scaffolds. Then the co-culture of two cell types in CPC scaffolds was discussed. Subsequently, to further enhance the prevascularization efficacy, tri-culture of three different cell types in CPC scaffolds was presented. (1) Arg–Gly–Asp (RGD) incorporation in CPC bone cement scaffold greatly enhanced cell affinity and bone prevascularization; (2) By introducing endothelial cells into the culture of osteogenic cells (co-culture of two different cell types, or bi-culture) in CPC scaffold, the bone defect area underwent much better angiogenic and osteogenic processes when compared to mono-culture; (3) Tri-culture with an additional cell type of perivascular cells (such as pericytes) resulted in a substantially enhanced prevascularization of CPC scaffolds in vitro and more new bone and blood vessels in vivo, compared to bi-culture. Furthermore, biological cell crosstalk and capillary-like structure formation made critical contributions to the bi-culture system. In addition, the pericytes in the tri-culture system substantially promoted stability and maturation of the primary vascular network. The novel approach of CPC scaffolds with stem cell bi-culture and tri-culture is of great significance in the regeneration of dental, craniofacial and orthopedic defects in clinical practice. [ABSTRACT FROM AUTHOR]

The objectives of this studywere to: (1) develop a novel bioactive nanocomposite for Class V restorations with subgingival margins to inhibit periodontal pathogens; and (2) investigate if the bioactive nanocomposite could inhibit multi-species periodontal biofilms with a potency as strong as that against single species biofilms. Nanocomposite was fabricated using dimethylaminohexadecyl methacrylate (DMAHDM), 2-methacryloyloxyethyl phosphorylcholine (MPC) and nanoparticles of amorphous calcium phosphate (NACP). Biofilms with 1, 3, 6 and 9 species of periodontal pathogens were grown on the composites and tested for live/dead staining, colony-forming units (CFU), metabolic activity, and biofilm matrix polysaccharide production. The bioactive composite reduced protein adsorption by an order of magnitude (p < 0.05) and greatly reduced biofilm viability. It decreased the biofilm CFU by more than 3 orders of magnitude for all four types of periodontal biofilms, compared to control composite. With increasing the biofilm species from 1 to 9, the antibacterial efficacy of DMAHDM composite decreased; the CFU reduction folds decreased from 947 folds to 44 folds. In contrast, the MPC + DMAHDM composite maintained a CFU reduction folds of greater than 3000, showing a similar antibacterial potency from 1 to 9 species in the biofilms (p > 0.1). Dual agents MPC + DMAHDM achieved the greatest inhibition in biofilm, without decreasing its antibacterial potency when the biofilm species was increased from 1 to 9. A single agent became less effective when the biofilm species was increased from 1 to 9. The multifunctional MPC + DMAHDM composite is promising for root caries treatment and Class V restorations with subgingival margins to effectively inhibit multispecies periodontal biofilms, combat periodontitis and protect the periodontium. [ABSTRACT FROM AUTHOR]