Streptococcus mutans adhesion on nickel titanium (NiTi) and copper-NiTi archwires: A comparative prospective clinical study

Objectives:To compare the adhesion of Streptococcus mutans to nickel titanium (NiTi) and copper-NiTi (Cu-NiTi) archwires and to correlate the adhesion to surface characteristics (surface free energy and surface roughness) of these wires.Materials and Methods:A total of 16 patients undergoing orthodontic treatment with preadjusted edgewise appliances were included in the study. 0.016” and 0.016” × 0.022” NiTi and Cu-NiTi archwires in as-received condition and after 4 weeks of intraoral use were studied for S mutans adhesion using real-time polymerase chain reaction. Surface roughness and surface free energy were studied by three-dimensional surface profilometry and dynamic contact angle analysis, respectively.Results:S mutans adhesion was more in Cu-NiTi archwires. These wires exhibited rougher surface and higher surface free energy when compared to NiTi archwires.Conclusions:S mutans adhesion, surface roughness, and surface free energy were greater in Cu-NiTi than NiTi archwires. Surface roughness and surface free energy increased after 4 weeks of intraoral exposure for all of the archwires studied. A predominantly negative correlation was seen between the cycle threshold value of adherent bacteria and surface characteristics.     

Effect of the cross-linking silane concentration in a novel silane system on bonding resin-composite cement

Objective. Four experimental blends of an organo-functional silane monomer with a non-functional cross-linking silane monomer (a novel silane system) were evaluated as adhesion promoters in an experiment in which a resin-composite cement was bonded to silica-coated titanium. Material and Methods. 3-Acryloyloxypropyltrimethoxysilane (as constant 1.0 vol%) was blended with 1,2-bis-(triethoxysilyl)ethane, where its concentration was 0.1, 0.2, 0.3, or 0.5 vol%. Titanium slides (n=20) were grit-blasted, silica-coated, and silanized with four experimental silane solutions, with a pre-activated silane Cimara? (VOCO, Germany) as control. After silanization, resin-composite cement stubs (Bifix? QM; VOCO, Germany) were photo-polymerized. The shear bond strength was measured after dry storage (24 h) or after thermo-cycling (6000 cycles between 5°C and 55°C). The resin stub failure mode was determined. Results. Statistical analysis (ANOVA) showed that type of storage (p <0.05) and concentration of cross-linker silane (p<0.005) both significantly affected the shear bond strength. The highest shear bond strength was obtained with a blend of 1.0 vol% 3-acryloyloxypropyltrimethoxysilane+0.3 vol% 1,2-bis-(triethoxysilyl)ethane, 15.9 MPa (standard deviation SD 3.4 MPa) for both the thermo-cycled group and after dry storage (24 h), 14.3 MPa (SD 4.1 MPa) (n=8/group). The lowest values were obtained with Cimara? silane 7.3 MPa (SD 2.2 MPa) in dry storage and 7.9 MPa (SD 2.0 MPa) obtained with 1.0 vol% 3-acryloyloxypropyltrimethoxysilane+0.1 vol% 1,2-bis-(triethoxysilyl)ethane. The failure type was mainly cohesive. Conclusion. A novel silane system with an optimal concentration of the cross-linking silane may produce significantly higher shear bond strength between silica-coated titanium and resin-composite cement compared to a pre-activated silane product.     

In Vitro Bioactivity and Biocompatibility of Dicalcium Silicate Cements for Endodontic Use

IntroductionThe purpose of this study was to examine the in vitro bioactivity and biocompatibility of sol-gel–derived dicalcium silicate cements.MethodsThe morphology, phase composition, and compressive strength of the novel cement were investigated after immersion in a simulated body fluid for different periods of time. Cement biocompatibility was evaluated by incubating the cement specimens with MG63 human osteoblast-like cells.ResultsAfter immersion in a simulated body fluid as little as 1 hour, the cements were covered with clusters of bone-like apatite spherulites. The characteristic peaks of apatite at 2θ = 25.9 degrees and 31.8 ? 32.9 degrees appeared. The compressive strength of the cement was increased from the initial strength value of 12.3 MPa to 1-day strength value of 20.2 MPa; these values were significantly different (P < .05). The MG63 cell viability increased 15% and 23% on the cement surfaces when compared with the control on hour 6 and day 7 of incubation, respectively. The cells appeared flat and exhibited intact, well-defined morphology on the cement surface.ConclusionsBoth bioactivity and biocompatibility of the dicalcium silicate cement consistently make it a potential candidate for endodontic use.     

Evaluation of Streptococcus mutans adhesion to fluoride varnishes and subsequent change in biofilm accumulation and acidogenicity

Objectives

The aim of this study was to evaluate Streptococcus mutans adhesion to fluoride varnishes and subsequent change in biofilm accumulation and acidogenicity.

Methods

After producing fluoride varnish-coated hydroxyapatite discs using Fluor Protector (FP), Bifluorid 12 (BIF), Cavity Shield (CASH), or Flor-Opal Varnish White (FO), S. mutans biofilms were formed on the discs. To assess S. mutans adhesion to the discs, 4-h-old biofilms were analysed. To investigate the change in biofilm accumulation during subsequent biofilm formation, the biomass, colony forming units (CFU), and water-insoluble extracellular polysaccharides (EP) of 46-, 70-, and 94-h-old biofilms were analysed. To investigate the change in acidogenicity, pH values of the culture medium were determined during the experimental period. The amount of fluoride in the culture medium was also determined during the experimental period.

Results

BIF, CASH, and FO affected S. mutans adhesion (67–98% reduction) and subsequent biofilm accumulation in 46-, 70-, and 94-h-old biofilms. However, the reducing effect of the fluoride varnishes on the biomass, CFU count, water-insoluble EP amount, and acid production rate of the biofilms decreased as the biofilm age increased. These results may be related to the fluoride-release pattern of the fluoride varnishes. Of the fluoride varnishes tested, FO showed the highest reducing effect against the bacterial adhesion and subsequent biofilm accumulation.

Conclusions

Our findings suggest that if the results of these experiments are extrapolable to the in vivo situation, then reduced clinical benefit of using fluoride varnishes may occur with time.

Clinical significance

Fluoride varnish application can affect cariogenic biofilm formation but the anti-biofilm activity may be reduced with time.     

Effect of adhesion boosters on indirect bracket bonding

Objective:To determine the influence of two adhesion boosters on shear bond strength and on the bond failure location of indirectly bonded brackets.Materials and Methods:Sixty bovine incisors were randomly divided into three groups (n  =  20), and their buccal faces were etched using 37% phosphoric acid. In group 1 (control), brackets were indirectly bonded using only Sondhi adhesive. In groups 2 and 3, the adhesion boosters Enhance Adhesion Booster and Assure Universal Bonding Resin, respectively, were applied before bonding with Sondhi. Maximum bond strength was measured with a universal testing machine, and the location of bond failure was evaluated using the Adhesive Remnant Index (ARI). One-way analysis of variance followed by the Tukey test (P < .05) was used to compare the shear bond strength among groups, and the differences in ARI scores were evaluated using the Kruskal-Wallis test (P < .05). The Pearson correlation coefficient was calculated to determine whether there was any correlation between bond strength and ARI scores.Results:The mean shear bond strength in group 3 was significantly higher (P < .01) than in the other groups. Evaluation of the locations of bond failure revealed differences (P < .05) among the three groups. There was a moderate correlation between bond strength and ARI scores within group 3 (r  =  0.5860, P < .01).Conclusion:In vitro shear bond strength was acceptable in all groups. The use of the Assure adhesion booster significantly increased both the shear bond strength of indirectly bonded brackets and the amount of adhesive that remained on the enamel after bracket debonding.     

Inhibitory effects of β-caryophyllene on Streptococcus mutans biofilm

ObjectiveThe biofilm of Streptococcus mutans is associated with induction of dental caries. Also, they produce glucan as an extracellular polysaccharide through glucosyltransferases and help the formation of cariogenic biofilm. β-caryophyllene has been used for therapeutic agent in traditional medicine and has antimicrobial activity. The purpose of this study was to investigate the effect of β-caryophyllene on S. mutans biofilm and the expression of biofilm-related factor.DesignThe susceptibility assay of S. mutans for β-caryophyllene was performed to investigate inhibitory concentration for S. mutans growth. To evaluated the effect of β-caryophyllene on S. mutans biofilm, β-caryophyllene was treated on S. mutans in the various concentrations before or after the biofilm formation. Live S. mutans in the biofilm was counted by inoculating on Mitis-salivarius agar plate, and S. mutans biofilm was analyzed by confocal laser scanning microscope after staining bacterial live/dead staining kit. Finally, the expression of glucosyltransferases of S. mutans was investigated by real-time RT-PCR after treating with β-caryophyllene at the non-killing concentration of S. mutans.ResultsThe growth of S. mutans was inhibited by β-caryophyllene in above concentration of 0.078%, S. mutans biofilm was inhibited by β-caryophyllene in above 0.32%. Also, 2.5% of β-caryophyllene showed anti-biofilm activity for S. mutans biofilm. β-caryophyllene reduced the expression of gtf genes at a non-killing concentration for S. mutans. On the basis on these results, β-caryophyllene may have anti-biofilm activity and the inhibitory effect on biofilm related factor.Conclusionsβ-caryophyllene may inhibit cariogenic biofilm and may be a candidate agent for prevention of dental caries.     

Inhibitory effects of the phenolic fraction from the pomace of Vitis coignetiae on biofilm formation by Streptococcus mutans

ObjectivesThe anti-cariogenic properties of the phenolic fraction from the pomace of Vitis coignetiae (VcPP) were evaluated by in vitro assays and compared with fruit juices from V. coignetiae and common grapes and with other phenolic fractions. The effects of VcPP against the biofilm of Streptococcus mutans were investigated.DesignSucrose-dependent biofilm formation by S. mutans cultured in the presence of VcPP was measured by crystal violet dye uptake. Inhibition of adhesion to the saliva-coated hydroxyapatite (sHA) beads was quantified using fluorescent-labelled cells. The MIC for S. mutans was determined by colony counting on agar plates containing VcPP. The ability of VcPP to inhibit glucan synthesis by three distinct recombinant glucosyltransferases (Gtfs) was assessed by quantifying the production of water-soluble and -insoluble polysaccharides in bacterial cultures. In addition, the buffering effect of VcPP in cultures of S. mutans was evaluated.ResultsVcPP reduced adhesion of S. mutans to sHA and biofilm formation in a dose-dependent manner. The MIC of VcPP was 7.50 mg/ml. VcPP inhibited GtfB activity associated with the synthesis of water-insoluble glucans. It also inhibited GtfD activity associated with the synthesis of water-soluble glucans at a concentration which was lower than that used for inhibition of GtfB. VcPP had no effect on acidification associated with glucose utilization by S. mutans.ConclusionsThe current study supports the potential of VcPP as a food additive for reducing caries by inhibiting adhesion to the tooth surface and GtfD-mediated soluble glucan synthesis.     

Influence of orthodontic brackets design and surface properties on the cariogenic Streptococcus mutans adhesion

ObjectiveTo compare the surface properties of self-ligating metallic (SLM), ceramic esthetic, and conventional metallic (CM) brackets, and evaluate the adhesion of Streptococcus mutans biofilms to their surface, attempting to interpret the correlation between bracket type and enamel demineralization from a microbiological perspective.Materials and methodsTwenty-two brackets of each group were used. The brackets’ surface roughness was defined and the bacterial adhesion was performed using the strain S. mutans ATCC25175 with 8 h or 24 h of incubation time. The total bacterial adhesion (TBA) of biofilms was assessed using optical density (OD) methodology. To quantify bacteria viability (BV), the colony forming units (CFU) were counted. A scanning electron microscopy (SEM) observation of biofilms was also performed. Results: Ceramic brackets exhibited significantly higher roughness (0.304) compared to CM (0.090) and SLM (0.067) ones (C > CM = SLM). The data obtained with the TBA and BV tests showed that S. mutans biofilm formed on bracket groups exhibited similar results for both incubation periods. From the SEM images it is possible to observe that biofilm structure formed for 24 h was denser than that for 8 h of incubation with significantly more aggregates and cells for three groups.ConclusionThis in vitro study suggests that despite the higher surface roughness of ceramic brackets, this alone does not influence the adhesion of the S. mutans biofilms.Clinical relevanceFrom a microbiological perspective, the bracket's design may be more relevant than its surface roughness with respect to the adhesion of cariogenic bacteria biofilm with potential risk to dental enamel integrity.     

Proteomic analysis of the biological response of MG63 osteoblast-like cells to titanium implants

Understanding of the interaction between human MG63 osteoblast-like cells and surfaces is necessary in the field of tissue engineering and biomaterials. Various titanium surfaces are widely used as not only implant materials, but also as miniscrews in orthodontics. Our goal was to assess the proteomic response of MG63 osteoblast-like cells to different titanium surfaces. MG63 osteoblast-like cells were cultured on three different titanium surfaces: a smooth surface (S), a sandblasted with large grit and acid-etched surface (SLA), and a surface coated with a thin layer of hydroxyapatite (HA). Cells grown on the rougher surfaces (SLA and HA) exhibited downregulated cell proliferation and morphological changes. In the proteomic analysis, cells grown on the SLA surface showed upregulated expression of protocadherin-β3 precursor, kinase insert domain receptor, fibroblast growth factor receptor-3, and insulin-like growth factor I, while the expression levels of cell adhesion kinase, collagen α-1(I) chain precursor, collagen type XI α2, and cadherin-11 were upregulated in cells grown on the HA surface. These proteins are known to be involved in osteoblast adhesion, growth, and differentiation. Thus, the surface properties of dental materials can influence the expression of proteins involved in osseointegration-related processes. Proteomic analysis may reveal changes in novel proteins that explain why osseointegration varies depending on surface properties.     

Initial oral biofilm formation on titanium implants with different surface treatments: An in vivo study

ObjectiveThe aim of this study was to examine in vivo the initial bacterial adhesion on titanium implants with different surface treatments.DesignTen subjects wore oral splints containing machined pure titanium disks (Ti-M), acid-etched titanium (Ti-AE) and anodized and laser irradiated disks (Ti-AL) for 24 h. After this period, disks were removed from the splints and adherent bacteria were quantified by an enzymatic assay to assess total viable bacteria and by Real Time PCR to evaluate total bacteria and Streptococcus oralis levels. Additionally, the initial adherent microorganisms were visualized by scanning electron microscopy (SEM). Titanium surface morphology was verified using SEM, and roughness was evaluated by profilometer analysis.ResultsRegarding titanium surface roughness, Ti-AL (1.423 ± 0.397) showed significantly higher Ra values than did Ti-M (0.771 ± 0.182) and Ti-AE (0.735 ± 0.196) (p < 0.05, ANOVA – Tahame). Ti-AE and Ti-AL presented roughened micro-structure surfaces characterized by open pores, whereas Ti-M showed long grooves alternating with planed areas. Comparing the Ti-M, Ti-AE and Ti-AL groups for viable bacteria (MTT assay), total bacteria and S. oralis quantification (qPCR), no significant differences were observed among these three groups (p > 0.05, ANOVA – Tahame). SEM images showed similar bacterial adhesion on the three titanium surfaces, predominantly characterized by cocci and several bacilli, indicating an initial colonization of the oral biofilm.ConclusionIn conclusion, roughness and microtopography did not stimulate initial biofilm formation on titanium surfaces with different surface treatments.     

人成骨样细胞在糖交联胶原支架材料中的黏附和整合素表达

目的探讨人成骨样细胞在糖交联胶原支架材料中的黏附和整合素表达。方法将SAOS-2细胞接种于糖交联胶原支架表面,共培养3周后,采用扫描电子显微镜观测材料表面细胞形态,通过细胞示踪、整合素(Integrin-β1)免疫荧光染色后激光共聚焦显微镜观测细胞活性和在材料表面的黏附。结果人成骨样SAOS-2细胞可在糖交联胶原支架材料表面黏附,形成细胞膜片样结构,并表达细胞黏附因子Integrinβ1。结论糖交联胶原支架材料表现出良好的生物相容性,可在体外促进人成骨样SAOS-2细胞的黏附,并诱导整合素Integrinβ1表达,进一步调控细胞向成骨方向分化。     

Antimicrobial activity of nanoemulsion on cariogenic Streptococcus mutans

Objective

To assess antimicrobial activities of nanoemulsion (NE) to control the adhesion and biofilm formation by Streptococcus mutans by in vitro.

Design

In vitro antimicrobial susceptibility of nanoemulsion was determined as per National Committee for Clinical Laboratory Standards guidelines and agar diffusion, serial dilution technique for the determination of minimum inhibitory concentration and minimum bactericidal concentration (MIC/MBC). Efficacy was tested by kinetics of killing, biofilm assay and scanning electron microscopy.

Results

: NE concentrations ranging from 1:100 to 1:10,000 dilutions were effective against S. mutans as shown through MIC/MBC assays. NE showed antimicrobial activity against planktonic cells at high dilutions, confirmed by time kill studies. 4-day-old S. mutans biofilms were treated with NE; subsequent reductions of bacterial cell counts were noticed with decreasing dilutions. Staining of NE-treated biofilms with LIVE/DEAD BacLight resulted in dead cell areas of up to 48% in 1 min, 84% at 1 h and significant (<0.05) increases in dead cell counts at all time points. Damage to cell membranes and cell walls of S. mutans by NE was demonstrated using scanning electron microscopy (SEM).

Conclusion

These results suggest that nanoemulsion has effective antibacterial activity against S. mutans and may be a useful medication in the prevention of dental caries.     

Adhesion properties in systems of laminated pigmented polymers,carbon–graphite fiber composite framework and titanium surfaces in implant suprastructures

ObjectiveFor long-term stability the adhering interfaces of an implant-retained supraconstruction of titanium/carbon–graphite fiber-reinforced (CGFR) polymer/opaquer layer/denture base polymer/denture teeth must function as a unity. The aim was to evaluate adhesion of CGFR polymer to a titanium surface or CGFR polymer to two different opaquer layers/with two denture base polymers.Materials and methodsTitanium plates were surface-treated and silanized and combined with a bolt of CGFR polymer or denture base polymer (Probase Hot). Heat-polymerized plates of CGFR polymer (47 wt% fiber) based on poly(methyl methacrylate) and a copolymer matrix were treated with an opaquer (Sinfony or Ropak) before a denture base polymer bolt was attached (Probase Hot or Lucitone 199). All specimens were heat-polymerized, water saturated (200 days) and thermally cycled (5000 cycles, 5/55 °C) before shear bond testing.ResultsSilicatized titanium surfaces gave higher bond strength to CGFR polymer (16.2 ± 2.34 and 18.6 ± 1.32) MPa and cohesive fracture than a sandblasted surface (5.9 ± 2.11) MPa where the fracture was adhesive. The opaquer Sinfony gave higher adhesion values and mainly cohesive fractures than the opaquer Ropak. Different surface treatments (roughened or polished) of the CGFR polymer had no effect on bond strength.SignificanceThe fracture surfaces of silicatized titanium/CGFR polymer/opaquer layer (Sinfony)/denture base polymers were mainly cohesive. A combination of these materials in an implant-retained supraconstruction is promising for in vivo evaluation.     

Sandblasted-acid-etched titanium surface influences in vitro the biological behavior of SaOS-2 human osteoblast-like cells

Osseointegrated dental implants have been successfully used over the past several years, allowing functional replacement of missing teeth. Surface properties of titanium dental implants influence bone cell response. Implant topography appears to modulate cell growth and differentiation of osteoblasts thus affecting the bone healing process. Optimal roughness and superficial morphology are still controversial and need to be clearly defined. In the present study we evaluated in vitro the biological behavior of SaOS-2 cells, a human osteoblast-like cell line, cultured on two different titanium surfaces, smooth and sandblasted-acid-etched, by investigating cell morphology, adhesion, proliferation, expression of some bone differentiation markers and extracellular matrix components. Results showed that the surface topography may influence in vitro the phenotypical expression of human osteoblast-like cells. In particular the tested sandblasted-acid-etched titanium surface induced a significantly increased Co I deposition and α2-β1 receptor expression as compared to the relatively smooth surface, promoting a probable tendency of SaOS-2 cells to shift toward a mature osteoblastic phenotype. It is therefore likely that specific surface properties of sandblasted-acid-etched titanium implants may modulate the biological behavior of osteoblasts during bone tissue healing.     

Evaluation of five dental silanes on bonding a luting cement onto silica-coated titanium

OBJECTIVES: Five commercial dental silanes were evaluated in vitro as adhesion promoters bonding a luting cement to silica-coated titanium surfaces. METHODS: Titanium slides (n=20) were cleaned with alumina sand and then silica-coated with a special sand consisting of alumina particles coated with silica. The bonding of a resin composite cement (3M ESPE, Seefeld, Germany) to silica-coated and silanized titanium was evaluated by using the dental silane (RelyX Ceramic Primer) that belongs to the RelyX ARC cementing kit, and comparing it to four other dental silanes (Bisco Porcelain Primer, Cimara, ESPE Sil, and Pulpdent Silane Bond Enhancer). The resin composite cement stubs (n=8) were light-polymerized onto a silanized silica-coated titanium surface. The shear bond strength of the cement stubs was measured after dry storage and thermo-cycling 6000 times between 5 and 55 degrees C. The silanes and their reactions were chemically monitored by using Fourier transform infrared analysis. RESULTS: Statistical analysis using ANOVA revealed that the brand of silanes and the types of storage condition differ significantly (p<0.005). The highest shear bond strength was obtained with RelyX ceramic silane in dry conditions (19.5+/-4.3 MPa), and after thermo-cycling (16.6+/-3.5 MPa). The lowest results were obtained using Pulpdent Silane Bond Enhancer, in dry conditions (7.8+/-2.2 MPa), and after thermocycling (5.3+/-2.4 MPa). The analysis showed that silanes had different pH values. Some differences were detected between the silanes and their reactions. CONCLUSIONS: Dental silanes provide different bonding strengths and have differences in their pH, solvent system and silane concentration.     

Behavior of CAL72 osteoblast-like cells cultured on zirconia ceramics with different surface topographies

OBJECTIVES: Because of its inherent strength, biocompatibility, and tooth-like color, zirconia ceramics have the potential to become an alternative to titanium as dental implant material. This study aimed at investigating the osteoblastic response to yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) with different surface topographies. METHODS: CAL72 osteoblast-like cells were cultured on machined (TZP-m), airborne particle abraded (TZP-s), and airborne particle abraded and acid-etched Y-TZP (TZP-sa) surfaces. Polystyrene and airborne particle abraded with large grit and acid-etched (SLA) titanium served as a reference control. The surface topography was examined by scanning electron microscopy (SEM) and profilometry. At culture days 3, 6, and 12, cell proliferation, at day 12 cell morphology, and cell-covered surface area were determined. RESULTS: The surface roughness of Y-TZP was increased by airborne particle abrasion and additionally by acid etching. No statistically significant differences were found between average roughness (R(a)) and maximum peak-to-valley height (R(p-v)) values of airborne particle abraded and acid-etched Y-TZP and SLA titanium. Whereas the cell proliferation assay revealed statistically significant greater values at day 3 for surface-treated Y-TZP and polystyrene cultures as compared with machined Y-TZP, no differences between the Y-TZP groups, SLA titanium, and polystyrene were observed at culture days 6 and 12. CONCLUSIONS: Cell morphology and cell-covered surface area were not affected by the type of substrate. The results suggest that roughened Y-TZP is an appropriate substrate for the proliferation and spreading of osteoblastic cells.     

Anti-biofilm activity of silver nanoparticle-containing glass ionomer cements

ObjectiveTo develop a silver nanoparticle (AgNP) formulation for incorporation into glass ionomer cements (GICs) which minimises biofilm growth on restoration surfaces.MethodsGICs, Fuji IX, Ketac Molar, and Riva Selfcure were modified with 6, 10 and 24 μg per GIC capsule of α-lipoic acid-capped AgNPs. Monoculture biofilms of Streptococcus mutans were cultured (72 h) on GIC specimens (n = 3) and biofilm accumulation was quantified using a viability stain with confocal laser scanning microscopy. Compression strength and flexural strength (CS & FS) were measured according to ISO 9917-1:2007 (n = 8, n = 25). GIC colour was measured at 0, 1, and 14 days following AgNP incorporation using a digital spectrophotometer. Silver release from AgNP-modified GIC specimens was monitored at 1, 3, 7 and 14 days using inductively coupled plasma-mass spectrometry.ResultsAgNP-modified Fuji IX demonstrated the greatest reduction in biofilm accumulation, with 10 μg Ag/capsule inhibiting biofilm formation by 99%. Ketac Molar and Riva Selfcure required 24 μg Ag/capsule to achieve 78% biofilm reduction. AgNP-modified GICs demonstrated significantly higher CS and FS than sintered silver-containing GICs, and possessed equivalent or higher strength values when compared to unmodified GICs. The colour shades of AgNP-modified GICs were more comparable to VITA shades of non-modified GICs than were sintered silver-containing GICs. The silver (≥99.6%) remained within the GIC for at least two weeks following incorporation.SignificanceAgNP-modified GICs exhibited significant antibiofilm activity and retained mechanical properties equivalent or superior to non-modified GICs. AgNP-modified GICs could reduce bacterial colonisation on and around restorations thereby reducing restoration failure caused by secondary caries.     

Development of novel dental restorative composites with dibasic calcium phosphate loaded chitosan fillers

The incorporation of antimicrobial agents in restorative dental composites has the potential to slow the development of carious lesions.ObjectiveThe objectives of the present study were to develop experimental composite resins with chitosan or chitosan loaded with dibasic calcium phosphate anhydrous (DCPA) particles and to demonstrate their antimicrobial potential without loss of mechanical properties or biocompatibility.MethodsChitosan and chitosan/DCPA particles were synthetized by the electrospray method. Experimental composites were formulated by adding 0, 0.5, or 1.0 wt% particles into a resin matrix along with 60 wt% barium glass. The degree of conversion and mechanical properties were measured after 1 and 90 days of aging in water after photoactivation. Cytotoxicity and genotoxicity were evaluated using fibroblasts from dental pulp in conditioned medium. The antimicrobial activity against Streptococcus mutans was assessed by crystal violet biofilm assay.ResultsThe experimental restorative composites were not found to be cytotoxic or genotoxic, with cell viability of 93.1 ± 8.0% (p = 0.328) and 3.0 ± 0.8% micronucleus per group (p = 0.1078), respectively. The antimicrobial results showed that all composites with approximately 20% less biofilm (p < 0.001) relative to the control. No chitosan release was detected from the composites, suggesting direct contact of the bacteria with exposed chitosan particles on the surface was responsible for the observed antimicrobial effect. The addition of the chitosan and chitosan/DCPA submicrometer (<250 nm average diameter) particles to restorative composites did not change the degree of conversion, flexural strength, elastic modulus and fracture toughness compared to the control group after 90 days aging in water.SignificanceIt can be concluded that the addition of chitosan or chitosan/DCPA particles in the restorative composites induced antimicrobial activity without compromising the mechanical properties or biocompatibility of the composites.     

Cytotoxicity of novel fluoride solutions and their influence on mineral loss from enamel exposed to a Streptococcus mutans biofilm

ObjectiveThis study evaluated the cytotoxicity, antimicrobial activity and in vitro influence of new fluoridated nanocomplexes on dental demineralization.DesignThe nanocomplexes hydroxypropyl-β-cyclodextrin with 1% titanium tetrafluoride (TiF₄) and γ-cyclodextrin with TiF₄ were compared to a positive control (TiF₄), a blank control (without treatment) and negative controls (hydroxypropyl-β-cyclodextrin, γ-cyclodextrin, deionized water), following 12- and 72-hour complexation periods. The cytotoxicity was assessed using the neutral red dye uptake assay at T1–15 min, T2–30 min and T3–24 h. A minimum bactericidal concentration (MBC) against Streptococcus mutans (ATCC 25175) was performed. Enamel blocks were exposed to an S. mutans biofilm, and the percentage of surface microhardness loss was obtained. Biocompatibility and microhardness data were analysed using ANOVA/Tukey tests (p < 0.05).ResultsAt T1, the cell viability results of the nanocomplexes were similar to that of the blank control. At T2 and T3, the 72 h nanocomplexes demonstrated cell viability results similar to that of the blank, while the 12 h solutions showed results different from that of the blank (p < 0.05). All fluoridated nanocompounds inhibited S. mutans (MBC = 0.25%), while the MBC of TiF₄ alone was 0.13%. All fluoridated compounds presented a percentage of surface microhardness loss lower than that of deionized water (p < 0.05).ConclusionsThe new fluoridated nanocomplexes did not induce critical cytotoxic effects during the experimental periods, whilst they did show bactericidal potential against S. mutans and inhibited enamel mineral loss.