Physico-mechanical and antimicrobial properties of an elastomeric ligature coated with reduced nanographene oxide-nano curcumin subjected to dual-modal photodynamic and photothermal inactivation against Streptococcus mutans biofilms.

BACKGROUND: White spot lesions (WSLs) are a common side effect of fixed orthodontic treatment. Streptococcus mutans is the primary causative agent of WSLs and dental caries on the teeth during treatment. According to the unique features of reduced graphene oxide-nano curcumin (rGO-nCur), this study aimed to investigate the mechanical properties and antimicrobial potency of rGO-nCur coated orthodontic elastomeric ligatures as a novel coating composite following dual-modal photodynamic inactivation (PDI) and photothermal inactivation (PTI) against S. mutans biofilms. METHODS: After confirmation of rGO-nCur synthesis and coating elastomeric ligatures with different concentration levels of 1.25, 2.5, 5, 7.5, and 10 % of rGO-nCur, tensile strength, force decay, extension to tensile strength, and contact angle of the coated elastomeric ligatures were measured using universal testing machine and sessile drop method, respectively. To investigate the mechanism through which irradiated rGO-nCur can inhibit the formation of S. mutans biofilms, intracellular reactive oxygen species (ROS) generation, and increase in temperature of rGO-nCur solutions under the 450 and 980 nm laser irradiation, respectively, were measured. The anti-biofilm activity and inhibition of water-insoluble extracellular polysaccharide (EPS) production ability of irradiated rGO-nCur coated elastomeric ligatures using a 450 nm diode laser (195 J/cm2), a 980 nm diode laser (195 J/cm2), and a combination of both (78 J/cm2 of irradiation from each one) (i.e., PDI, PTI, and dual-modal PDI/PTI, respectively) were determined. Also, the expression of virulence genes involved in biofilm formation (comDE, gtfD, and smuT) was assessed by quantitative real-time polymerase chain reaction (RT-qPCR) following the mentioned treatment. One-way ANOVA test and Tukey post-hoc test at a p-value equal to/or less than 0.05 were used to analyze the obtained data. RESULTS: The synthesis of GO nano-sheets in a layered structure with a thickness of 0.76 nm was confirmed by AFM analysis. FESEM showed that the exfoliated sheet of synthesized GO had several micrometers in lateral size. DLS revealed that the mean particle size and density index of synthesized nCur were 57.47 ± 2.14 nm and 10 % respectively. In DLS analysis, rGO-nCur showed more positive surface charge (24 mV) than the nano-sheets of GO. FESEM confirmed the coating of rGO-nCur on elastomeric ligatures. ANOVA revealed that tensile strength of 1.25, 2.5, and 5 % rGO-nCur coated elastomeric ligatures were not decreased statistically significantly (P > 0.05). Mean tensile strength and recorded force of 7.5 and 10 % rGO-nCur coated elastomeric ligatures decreased significantly after 14 days' immersion in the artificial saliva (P < 0.05). On the 28th day of the study, the mean of the tensile strength of elastomeric ligatures coated with 10 % rGO-nCur (13.03 ± 0.10 N) was recorded as 55.90 % of the initial tensile strength (23.31 ± 0.41 N in uncoated elastomeric ligatures), while the mean tensile strength of elastomeric ligatures coated with 7.5 % rGO-nCur (16.01 ± 0.10 N) was measured as 68.94 % of the initial tensile strength (23.22 ± 0.09 N in uncoated elastomeric ligatures). When comparing the coated elastomeric ligatures at 7.5 % and 10 % to the original uncoated elastomeric ligatures at similar time intervals, statistically significant decreases in extension to tensile strength (0.42 to 0.71 mm or 3.02 to 5.05 %; all P < 0.05) were observed. The largest contact angle was measured in elastomeric ligatures coated by 10 % rGO-nCur followed by 7.5 and 5 % rGO-nCur (128 ± 2.19°, 117 ± 2.23°, and 99 ± 1.83°; respectively). The results revealed a rise of 6.4-fold in intracellular ROS and an 11.2 °C increase in the temperature of rGO-nCur solutions following the 450 nm and 980 nm laser irradiation, respectively. The 5 % rGO-nCur coated elastomeric ligature mediated dual-modal PDI/PTI showed the most inhibition of the biofilm formation of S. mutans by 83.62 % (P = 0.00). Significant reductions in water-insoluble EPS were detected in biofilm cultures of S. mutans on 1.25 % rGO-nCur coated elastomeric ligatures following irradiation with dual waves of the 450 nm and 980 nm diode lasers (i.e., dual-modal PDI/PTI; 96.17 %; P = 0.00). The expression levels of comDE, gtfD, and smuT virulence genes were significantly downregulated (7.52-, 13.92-, and 8.23-fold, respectively) in the biofilm cultures of S. mutans on 1.25 % rGO-nCur coated elastomeric ligatures following dual-modal PDI/PTI in comparison with biofilm cultures on non-coated elastomeric ligatures. CONCLUSION: 5 % rGO-nCur coated elastomeric ligatures following irradiation with dual waves of the 450 and 980 nm diode lasers (dual-modal PDI/PTI), without adverse effects on the physico-mechanical properties of elastomeric ligatures, can be used to inhibit the formation of S. mutans biofilms on the coated elastomeric ligatures around orthodontic brackets.

Effects of nano-micelles curcumin-based photodynamic therapy on expression of RUNX2 as an indicator of bone regeneration in orthodontic tooth movement.

OBJECTIVES: The aim was to evaluate the impact of nano-micelles curcumin (NMCur) based photodynamic therapy (PDT) during compressive force application on human PDL-derived fibroblasts (HPDFs) in vitro for up to 6 days on the expression of RUNX2 as an indicator of bone development and remodeling. MATERIALS AND METHODS: HPDFs viability during 2 g/cm2 compressive force application was investigated using membrane-impermeable DNA-binding stain propidium iodide (PI) in flow cytometry. Gene and protein expressions of RUNX2 were assessed by quantitative reverse transcription polymerase chain reaction (RT-qPCR) and flow cytometry, respectively, following NMCur-PDT at different concentrations of NMCur (25, 50, and 75 µM plus irradiation of 180 mW/cm2 diode laser at the wavelength of 450 ± 10 nm for 5 min) during the static compressive force of 2 g/cm2 on HPDFs via weight approach-based in-vitro loading model up to 6 days. One-way ANOVA and Tukey post hoc tests at a p-value equal to/or less than 0.05 were used to analyze the obtained data. RESULTS: After 6 days of application of compressive force, 99.21 ± 6.12% of HPDFs were PI negative and therefore considered alive, while only 0.89 ± 0.06% of the population were PI positive and considered dead. In comparison with controls (loaded HPDFs), expression of RUNX2 gene was dose-dependent and the highest expression (14.38-fold; P < 0.01) was observed at a concentration of 75 µM NMCur following 5 min of diode laser irradiation (i.e., 75 µM NMCur-PDT) during compressive force application on day 5. The greatest and lowest upregulations of RUNX2 protein were observed in 75 µM NMCur-PDT during compressive force application on HPDFs, on day 5 (3.19-fold; P < 0.01) and day 6 (2.09-fold; P < 0.05), respectively. CONCLUSION: NMCur-PDT during weight approach-based in-vitro loading model can promote orthodontic tooth movement by upregulating RUNX2 signaling pathway in HPDFs.

In vitro assessments of antimicrobial potential and cytotoxicity activity of an orthodontic adhesive doped with nano-graphene oxide.

INTRODUCTION: Formation of white spots and initial carious lesions are the most important complications of fixed orthodontic treatment. Preparation of orthodontic adhesives containing antimicrobial agents might be a practical solution for the prevention of the mentioned defects.

The synergistic effect of Nano-propolis and curcumin-based photodynamic therapy on remineralization of white spot lesions: An ex vivo study.

OBJECTIVE: One of the major problems in fixed orthodontic treatments is the control of enamel demineralization, white spots lesions (WSL), and dental caries around the brackets, which can be stopped by strengthening the remineralization process. The aim of this study was to investigate the synergistic effect of propolis nanoparticles (NPro) and nano-curcumin-based photodynamic therapy (NCur-PDT) in the remineralization of WSL ex vivo. MATERIALS AND METHODS: Experimental period was 5.5 months. After synthesis and characterization of NPro, the extracted bovine teeth were demineralized using a demineralization solution. They were divided into 7 groups (n=10) and treated in the following groups: 1) Negative control (artificial saliva), 2) Positive control or control of treatment (2% neutral sodium fluoride gel; NSF), 3) Nano-curcumin (NCur), 4) NPro, 5) Diode laser irradiation (light), 6) NCur with irradiation (NCur-PDT) and 7) NPro plus NCur-PDT (NPro+NCur-PDT). The treatment duration was 3 months and each treatment was conducted on T1 (the end of the third week), T2 (the end of the sixth week), T3 (the end of the ninth week), and T4 (the end of the twelfth week). Then, the microhardness, surface changes, and surface topography of the enamel were examined using digital hardness tester, DIAGNOdent Pen Reading, and scanning electron microscope (SEM), respectively. RESULTS: In all groups, after demineralization, the microhardness of tooth enamel decreased and after each of the treatments, the amount of microhardness significantly increased over time except light and artificial saliva groups. The earliest significant change in microhardness improvement was observed in the NPro+NCur-PDT group at T2 (P<0.05). Also, at T2, DIAGNODent Pen revealed the earliest significant improved change in the level of mineralization degree in the NPro+NCur-PDT group. NCur and light irradiation groups alone, like the control group (artificial saliva), did not lead to remineralization (P>0.05). Also, the NPro+NCur-PDT treatment results obtained from SEM after the last treatment in the twelfth week showed that remineralization in that group has significantly improved compared to other groups. CONCLUSION: The results of this study showed that combined use of NPro and NCur-PDT had more enamel remineralization efficacy in a shorter period. Simultaneous application of NPro and NCur-PDT had also a stronger therapeutic effect after 3 months.

The effects of bimodal action of photodynamic and photothermal therapy on antimicrobial and shear bond strength properties of orthodontic composite containing nano-graphene oxide.

BACKGROUND: White spot lesions are a common adverse effect of fixed orthodontic treatment and represent the main challenge to achieving esthetic appearance. The purpose of the current study was to evaluate physico-mechanical and antimicrobial potency of orthodontic composite (OC; Transbond XT) containing nano-structured graphene oxide (nGO) (OC-nGO) as a novel composite following photodynamic therapy (PDT) and photothermal therapy (PTT) against Streptococcus mutans. MATERIALS AND METHODS: Following preparation of OC-nGO, shear bond strength (SBS) and adhesive remnant index (ARI) of the test OC-nGO (containing 1, 2, 5, and 10% wt. nGO) were measured using a universal testing machine and stereomicroscope, respectively. The antimicrobial activities of test OC contained different concentrations of nGO were determined by disk agar diffusion (DAD), biofilm formation inhibition, and eluted components assays. After continuously rinsed in the aging process (up to 180 days), the antimicrobial activity of OC-nGO containing the highest concentration of nGO which had simultaneously the highest antimicrobial activity and SBS value were determined by DAD, biofilm formation, metabolic activity, and gtfB gene expression assays following photo-activation using diode laser irradiation against S. mutans. Data were analyzed using One-way Analysis of Variance (ANOVA). The Bonferroni post hoc test was used for comparison between the experimental groups. The significant difference was considered at P values < 0.05. RESULTS: OC with 5% wt. nGO showed simultaneously the highest SBS value (10.64 ± 2.76 MPa, P < 0.05) an antimicrobial and anti-biofilm activities. The OC-nGO in all test concentrations of nGO had ARI scores as same as control group (Transbond XT without the nGO) (P < 0.05). In microbial biofilm formation and gene expression assays, the reduction of photothermal disinfection and anti-virulence activities of the 5% wt. OC-nGO against test bacterium was associated with the time of aging process, so they were reduced significantly up to day 150. Diode laser irradiated 5% wt. OC-nGO suppressed 15.6 and 8.1-fold gtfB mRNA expressions in the biofilm growth of the S. mutans at days 120 and 150 of rinsing (P < 0.05). Microbial biofilm formation and gtfB gene expression in S. mutans at day 180 following PAD had a high level of similarity with OOC as the control group. 5% wt. OC-nGO following photo-activation was not colonized by the S. mutans at day 90 and significant suppressed 91.98% and 76.37% of S. mutans biofilm formation at day 120 and 150, respectively (both P < 0.05). From day 120 onwards, metabolic activity was progressively increased on laser-irradiated 5% wt. OC-nGO discs compared to the control group (OC alone). Photo-activated OC-nGO containing 5% wt. nGO suppressed 86.94% and 46.82% metabolic activity of the S. mutans at days 120 and 150 of rinsing (both P < 0.05). CONCLUSIONS: Our data support that the photo-activated 5% wt. OC-nGO can serve as an orthodontic composite/adhesive additive to control cariogenic bacterial biofilms.

An orthodontic acrylic resin containing seaweed Ulva lactuca as a photoactive phytocompound in antimicrobial photodynamic therapy: Assessment of anti-biofilm activities and mechanical properties.

BACKGROUND: Uncontrolled accumulation of microbial plaque and formation of biofilm on the surface orthodontic acrylic removable appliances increases the risk of enamel decalcification and periodontal diseases. The purpose of the present study was to evaluate antimicrobial activities, anti-virulence potencies, and mechanical properties of orthodontic acrylic resin containing different concentrations of Ulva lactuca (a green marine macroalga) following photo-activation against Streptococcus mutans. MATERIALS AND METHODS: Minimum inhibitory concentration (MIC) of U. lactuca was determined against S. mutans. Acrylic resin specimens with different concentrations of U. lactuca (0.2 %, 0.5 %, 1%, 2.5 %, 5%, and 10 % weight/weight) were fabricated. Flexural strength values, antimicrobial effects, and anti-biofilm activities of samples were assessed in comparison with original acrylic resin as the control group. Also, the expression of the virulence-associated genes was assessed by quantitative real-time polymerase chain reaction. RESULTS: U. lactuca at concentrations of 1-10% significantly reduced the S. mutans growth rate by 20.3%-63.3% in comparison to the control group (P < 0.05). Therefore, the concentration of 1% of U. lactuca was considered as a MIC. The highest and lowest flexural strength values were observed in the control group (43.5 ± 2.4 MPa) and the group with a 10 % concentration of U. lactuca (19.2 ± 1.8 MPa), respectively. Flexural strength values decreased in samples containing 2.5 %, 5%, and 10 % concentrations of U. lactuca in comparison to the control group significantly (P > 0.05). In the disc agar diffusion test, the growth inhabitation zones around samples containing different concentrations of photo-activated U. lactuca ranged from 13 mm to 25 mm in diameter. Interestingly, the anti-biofilm activity of U. lactuca-mediated aPDT against S. mutans was dose-dependent. Additionally, the sub-MIC dose of U. lactuca (0.5 %) following photo-activation could significantly decrease the expression levels of gtfB, gtfC, and gtfD to 4.1-, 5.3-, and 7.4-fold, respectively. CONCLUSIONS: Adding photo-activated U. lactuca to the orthodontic acrylic resin at a concentration of 1% increases its antibacterial and anti-biofilm activities besides not detrimentally affects its flexural strength.

Comparing the Clinical Success Rate of Self-Drilling and Self-Tapping Mini-screws in the Retraction of Maxillary Anterior Teeth

Objective: To compare the success of self-drilling and self-tapping methods in the retraction of maxillary anterior teeth. Material and Methods: The study was conducted in 57 subjects with Cl II malocclusion who needed to be treated with extraction of four maxillary teeth. The selftapping method was used on the left side and the self-drilling method was used on the right side. Then, the pain rate of each method was recorded by the numerical rating scale (NRS). Statistical analysis was done by t-test and Chi-square test. The significance level in this study was considered at p-value<0.05. Results: Considering the clinical mobility as the failure, the success of treatment was equal in both methods and was 93%. The inflammation around the mini-screws was 8.8%. A significant relationship was found between the variables inflammation and success (p<0.05). The mean pain was 2.47 but there was no significant difference between the two methods in terms of pain score (p>0.05). There was a significant difference between the groups (p=0.03). The pain was significantly higher in the female. Conclusion: There is no difference between self-drilling and self-tapping methods in terms of success. Comparison of the pain between two genders according to the replantation method showed a significant difference in pain sensation between two genders. The pain sensation mean in female group was greater than male group.

Physico-mechanical and antimicrobial properties of an orthodontic adhesive containing cationic curcumin doped zinc oxide nanoparticles subjected to photodynamic therapy.

BACKGROUND: Potential complications on the crown level during fixed orthodontic procedures are white spot, enamel demineralization and tooth decay. This study evaluated the antimicrobial properties of an orthodontic adhesive incorporating cationic curcumin doped zinc oxide nanoparticles (cCur/ZnONPs), which can have the highest concentration of cCur/ZnONPs and shear bond strength (SBS) value simultaneously, against cariogenic bacteria including Streptococcus mutans, Streptococcus sobrinus, and Lactobacillus acidophilus. MATERIALS AND METHODS: Following synthesis and confirmation of cCur/ZnONPs, SBS and adhesive remnant index (ARI) of the test adhesives containing cCur/ZnONPs (1.2, 2.5, 5, 7.5, and 10% wt.) were measured using universal testing machine and stereomicroscope, respectively. After continuously rinsed (up to 180 day), the residual antimicrobial ability of modified adhesives which can have the highest concentration of cCur/ZnONPs and SBS value simultaneously were determined by disc agar diffusion (DAD), biofilm formation inhibition, and metabolic activity assays following photo-activation using light-emitting diode (LED) for 5 min against multispecies cariogenic biofilm-producing bacteria. RESULTS: Adhesive with 7.5% wt. cCur/ZnONPs showed the highest concentration of cCur/ZnONPs and SBS value (14.89 ± 3.26 MPa, P < 0.05) simultaneously. No significant differences in ARI scores were found between the modified adhesive and control (Transbond XT without the cCur/ZnONPs). 7.5% wt. cCur/ZnONPs following photo-activation was not colonized by the test microorganisms and suppressed 100% metabolic activity of the test microorganisms up to 90 day compared to the control group (cCur/ZnONPs free LED irradiation; P < 0.05). In DAD assay, the reduction of photodynamic disinfection of the 7.5% wt. cCur/ZnONPs against test bacteria was positively associated to the time, in such a way that it was decreased significantly after 60 day. From days 120 onwards, microbial biofilm formation and metabolic activity was progressively increased on 7.5% wt. cCur/ZnONPs adhesive discs compared to the control group (cCur/ZnONPs free LED irradiation). CONCLUSIONS: Our findings highlight the photo-activated 7.5% wt. cCur/ZnONPs can serve as an orthodontic adhesive additive to control the cariogenic multispecies biofilm, and also to reduce their metabolic activity.