Fluoride-amorphous calcium phosphate and biomimetic nano-hydroxyapatite for enamel remineralization: An in-vitro study of surface microhardness and composition.

AIM: Fluoride-Amorphous Calcium Phosphate and Biomimetic Nano-Hydroxyapatite for Enamel Remineralization; An In-Vitro Study of Surface Microhardness and Composition. MATERIAL AND METHODS: Ninety-six extracted human premolars with sound buccal surface were divided using a randomization computer-generating software into four groups; Group I (control) sound untreated enamel, Group II (demineralized) demineralized to create white spot lesions, Group III (biom-n-HA) demineralized and then treated with biomimetic nanohydroxyapatite cream, and Group IV (F-ACP) demineralized and then treated using Fluoride-Amorphous Calcium Phosphate varnish. Each group was divided into two subgroups; subgroup "A" evaluated for mineral content using energy dispersive x-ray spectroscopy (EDX) and for surface microhardness using the Vickers microhardness test and Subgroup "B" evaluated for white spot lesion depth using a polarized light microscope (PLM). RESULTS: The highest microhardness (VHN) was found in the (F-ACP) group (mean=428.61±54.43) and then in the (Biom-n-HA) group (mean=408.11±70.16) followed by the (Control) group (mean=402.13±53.40) with no significant difference between them and finally in the significantly different (Demineralized) group (mean=256.99±45.83). The weight percentage of Ca (30.29±1.04 and 33.44±1.07) and Ca/P ratio (1.87±0.06 and 2.03±0.05) were significantly different between Group III and Group IV respectively. PLM measurements in Group II (198.83µm), Group III (60.17µm), and Group IV (26.33µm) were significantly different. CONCLUSIONS: Both the (Biom-n-HA) cream and the (F-ACP) varnish showed promising results for enamel remineralization. The increased enamel surface microhardness was consistent with the mineral content and the changes in the birefringence.

Static friction, surface roughness, and antibacterial activity of orthodontic brackets coated with silver and silver chitosan nanoparticles.

BACKGROUND: To determine the effect of silver and silver chitosan nanocoatings on monocrystalline ceramic, polycrystalline ceramic, and metallic brackets regarding friction, roughness, and antibacterial effect against Streptococcus mutans. METHODS: A total of 99 upper right premolar brackets with a 0.022 × 0.025 -inch slot were divided into three groups, each 33 according to coating material; the non-coated group, silver nanoparticles (AgNPs), and silver chitosan nanoparticles (Ag-CsNPs) groups. Each group was equally subdivided into the following three subgroups regarding bracket materials: monocrystalline ceramic, polycrystalline ceramic, and metallic brackets. A universal testing machine determined static friction on a custom-made acrylic jig. Then a profilometer machine was used to collect roughness data, and finally, the anti-cariogenic effect was measured with the disc diffusion technique's "minimum zone of inhibition" against Streptococcus mutans. Two-way ANOVA was used to compare data between groups and subgroups, followed by the Bonferroni test for multiple pair-wise comparisons. RESULTS: The nanocoating effect on ceramic brackets' static friction was non-significant. The AgNPs and Ag-CsNPs coated metallic group revealed a significant increase in static friction-a significant effect of the nanocoating in the surface roughness of monocrystalline and polycrystalline ceramic brackets. A significant favorable effect of AgNPs and Ag-CsNPs against Streptococcus mutans was observed. CONCLUSIONS: AgNPs and Ag-CsNPs coats are unsuitable for decreasing friction in metallic brackets or improving roughness in polycrystalline ceramic brackets. Nano coating can improve roughness in monocrystalline ceramic brackets. Coating brackets with AgNPs and Ag-CsNPs has a tremendous antibacterial effect on Streptococcus mutans, a substantial factor in the incidence of dental caries.

Effect of self-assembling peptide and other remineralizing agents on preventing initial enamel lesions around orthodontic brackets: An in vitro comparative study.

OBJECTIVE: To investigate and compare the effect of self-assembling peptide SAP (P11-4), casein phosphopeptide-amorphous calcium phosphate fluoride paste (CPP-ACPF), and fluoride varnish (FV) on preventing enamel demineralization around orthodontic brackets. MATERIAL AND METHODS: Orthodontic brackets were bonded to the buccal surfaces of 80 freshly extracted human maxillary premolars. Teeth were randomly assigned to four groups (n=20) according to the remineralizing agent used as follows: SAP (P11-4) group (Curodont™ Protect/Credentis), CPP-ACPF group (MI Paste Plus®/Recaldent™), fluoride varnish group (Profluoride varnish®/VOCO), and control group. All products were applied according to the manufacturer's instructions. Specimens were cycled in daily refreshed demineralizing and remineralizing solutions for 8h and 16h, respectively, for 28 days. The calcium/phosphorus ratio (Ca/P) and surface microhardness (SMH) were evaluated at baseline and at two and four weeks. Two-way ANOVA (analysis of variance), one-way ANOVA and repeated measures ANOVA were used for statistical analysis. RESULTS: Two-way ANOVA demonstrated significant differences between remineralizing agents and time points. After 4 weeks, the SAP (P11-4) group had had significantly higher Ca/P ratio and SMH (1.68±0.11 and 346.47±55.38) compared to other groups, followed by CPP-ACPF (1.52±0.19 and 283.53±64.75), FV (1.37±0.14 and 262.80±82.98), and the control group (1.31±0.10 and 213.00±41.95). Significantly higher Ca/P ratio and SMH were observed at 2 weeks in the control group (1.44±0.10 and 269.63±57.37) and FV group (1.52±0.09 and 321.17±55.24) compared to 4 weeks. No significant differences were found regarding Ca/P ratio and SMH at 2 weeks in the CPP-ACPF (1.55±0.15 and 295.14±53.88) and SAP P11-4 groups (1.64±0.10 and 320.18±58.04) compared to 4 weeks. CONCLUSION: SAP (P11-4) had the greatest remineralizing efficacy compared to FV and CPP-ACPF. Moreover, extended period of time improved the preventive efficacy of SAP (P11-4) compared to the other regimens.

Effects of food-simulating solutions on the surface properties of two CAD/CAM resin composites.

Background: During clinical service, dental materials could experience chemical degradation due to exposure to different diet components which could affect their functions and longevity. So, the objective of this study was to investigate the effect of food simulating solutions on surface properties of two CAD/CAM dental resin composites. Material and Methods: Two CAD/CAM composites; a nano-hybrid and a resin nano-ceramic were machined into 2 mm plates then assessed at baseline for their surface roughness and microhardness. Each group was immersed into distilled water, ethanol and methyl ethyl ketone (MEK) for 15 days at 37oC. The surface properties were evaluated after one day, 10 and 15 days of immersion by a surface profilometer and Vickers microhardness tester, and finally the surface morphology was studied using scanning electron microscopy. Results: At baseline, there was no significant difference in roughness between Teric CAD and Lava Ultimate, however, Lava Ultimate was significantly harder than Tetric CAD. Aging in ethanol had no significant effect on roughness and hardness of both the materials. Yet, Lava Ultimate showed significantly higher roughness and hardness compared to Tetric CAD. Immersion in MEK resulted in a significant increase in roughness of Lava Ultimate at 10 and 15 days. Neverthless, it caused a significant decrease in hardness of Tetric CAD at 10 and 15 days and Lava Ultimate at 10 days. Finally, water immersion caused a significant increase of roughness Tetric CAD. Conclusions: Exposure to different storage media variably affected the surface properties of CAD/CAM machinable composites. Both materials showed greater stability in surface properties when being immersed in ethanol than MEK. Hence, the surface deterioration suggests the advisability of more research involving increased immersion periods and involvement of thermocycling changes. Key words:Food simulating solutions, chemical degradation, nano-hybrid CAD/CAM composite, resin nano-ceramic CAD/CAM material, surface roughness, micro-hardness, surface morphology.

Depth of cure of dual- and light-cure bulk-fill resin composites.

PURPOSE: To evaluate the degree of conversion (DC), Vickers microhardness (VMH), and depth of cure of dual-cure and light-cure bulk-fill resin composites (BFRCs). METHODS: One dual-cure (Fill-Up) and two light-cure (QuiXfil and Tetric N-Ceram Bulk Fill) BFRCs were investigated. For each tested BFRC, 11 cylindrical specimens (5 mm diameter, 4 mm height) were prepared, and light cured for 10 seconds (n= 11). DC was obtained by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and VMH was obtained using a VMH tester. The specimens were measured for DC and VMH at top and bottom surfaces. Statistical analysis was performed using two-way ANOVA, Tukey's post-hoc, and Pearson correlation tests (P< 0.05). RESULTS: Fill-Up and Tetric N-Ceram Bulk Fill revealed significantly higher DC and VMH values on the top surfaces than that on the bottom surfaces, whereas QuiXfil revealed no significant difference between top and bottom surfaces for DC and VMH. All tested BFRCs showed bottom/top ratios >80% for both DC and VMH. Each tested BFRC showed a significant positive correlation between DC and VMH. All tested BFRCs had adequate depth of cure, but only QuiXfil had a uniform depth of cure. Both DC and VMH bottom/top ratios were effective for depth of cure evaluation. CLINICAL SIGNIFICANCE: QuiXfil, Tetric N-Ceram Bulk Fill, and Fill-Up BFRCs were well cured up to a 4 mm depth. Although Fill-Up (dual-cure) can be used with its chemical-curing mode, light curing improved DC and VMH values of the top layer. Distinct variance in DC and VMH among the three tested BFRCs may affect their clinical performance.

Evaluation of zinc-oxide nanocoating on the characteristics and antibacterial behavior of nickel-titanium alloy.

OBJECTIVE: To investigate the effect of ZnO nanocoating on mechanical properties of NiTi orthodontic wires and antibacterial activity. METHODS: 0.016 x 0.022-in NiTi orthodontic wires were coated with ZnO nanoparticles using an electrochemical deposition method with three electrodes system in 0.1M Zn(NO3)2. Mechanical properties and frictional resistance of the coated wires were investigated using an universal testing machine. Antibacterial effect of ZnO coating was also investigated. RESULTS: A stable adhered ZnO nanocoating on NiTi wires was obtained. The coated wires have a significant antibacterial activity against S. aureus, S. pyogens and E. coli, and a reduction of frictional forces by 34%. CONCLUSION: ZnO nanocoating may improve the antibacterial effects of NiTi wires and reduce the frictional resistance. Coating may be implanted in orthodontic practice for faster and safer treatment.

Evaluation of zinc-oxide nanocoating on the characteristics and antibacterial behavior of nickel-titanium alloy

ABSTRACT Objective: To investigate the effect of ZnO nanocoating on mechanical properties of NiTi orthodontic wires and antibacterial activity. Methods: 0.016 x 0.022-in NiTi orthodontic wires were coated with ZnO nanoparticles using an electrochemical deposition method with three electrodes system in 0.1M Zn(NO3)2. Mechanical properties and frictional resistance of the coated wires were investigated using an universal testing machine. Antibacterial effect of ZnO coating was also investigated. Results: A stable adhered ZnO nanocoating on NiTi wires was obtained. The coated wires have a significant antibacterial activity against S. aureus, S. pyogens and E. coli, and a reduction of frictional forces by 34%. Conclusion: ZnO nanocoating may improve the antibacterial effects of NiTi wires and reduce the frictional resistance. Coating may be implanted in orthodontic practice for faster and safer treatment.

RESUMO Objetivos: Avaliar o efeito do nanorrevestimento de óxido de zinco (ZnO) sobre as propriedades mecânicas e propriedades antibacterianas de fios ortodônticos de NiTi. Métodos: Fios 0,016" x 0,022" de NiTi foram revestidos com nanopartículas de ZnO por meio de um método de deposição eletroquímica com um sistema de três eletrodos a 0,1M Zn(NO3)2. Uma máquina universal de testes foi utilizada para avaliar as propriedades mecânicas e a resistência friccional dos fios revestidos. Além disso, também foram analisadas as propriedades antibacterianas do revestimento de ZnO. Resultados: Obteve-se uma aderência estável das nanopartículas de ZnO sobre os fios NiTi. Os fios revestidos apresentaram atividade antibacteriana significativa contra S. aureus, S. pyogens e E. coli, e apresentaram uma redução de 34% na força de atrito. Conclusão: O revestimento com nanopartículas de óxido de zinco pode melhorar as propriedades antibacterianas e reduzir a resistência friccional dos fios de NiTi. Assim, o revestimento dos fios pode ser utilizado na Ortodontia visando tratamentos mais rápidos e seguros.

Evaluation of color changes of white spot lesions treated with three different treatment approaches: an in-vitro study.

OBJECTIVE: To qualitatively and quantitatively assess the color changes effect and the color stability of the resin infiltrant on white spot lesions (WSLs), in comparison with nano-hydroxyapatite (nano-HA) toothpaste and microabrasion. METHODS: WSLs were artificially created on sixty human premolars enamel surfaces and randomly assigned to equal four groups (n = 15 each): nano-HA toothpaste, microabrasion (Opalusture), resin infiltrant (Icon) treatment, or artificial saliva (control group). The color change (ΔE) of each specimen was measured by dental spectrophotometer (Vita Easyshade) at different time points: baseline, after WSLs' creation, after application of treatments, one month, three and six months after treatments application. RESULTS: The ΔE value did not differ significantly for the four groups at baseline measurement before treatment (p> 0.05). Icon resin infiltrant improved the color of WSLs significantly immediately after its application, giving the lowest ΔE value (3.00 ± 0.59), when compared to other treatments (p< 0.001). There were no significant changes in ΔE (p> 0.05) for all groups during the follow up intervals (one month, three and six months after treatments application). CONCLUSION: Resin infiltrant can improve the color of WSLs and restore the natural appearance of enamel better than nano-HA toothpaste and microabrasion.

Evaluation of color changes of white spot lesions treated with three different treatment approaches: an in-vitro study

ABSTRACT Objective: To qualitatively and quantitatively assess the color changes effect and the color stability of the resin infiltrant on white spot lesions (WSLs), in comparison with nano-hydroxyapatite (nano-HA) toothpaste and microabrasion. Methods: WSLs were artificially created on sixty human premolars enamel surfaces and randomly assigned to equal four groups (n = 15 each): nano-HA toothpaste, microabrasion (Opalusture), resin infiltrant (Icon) treatment, or artificial saliva (control group). The color change (ΔE) of each specimen was measured by dental spectrophotometer (Vita Easyshade) at different time points: baseline, after WSLs' creation, after application of treatments, one month, three and six months after treatments application. Results: The ΔE value did not differ significantly for the four groups at baseline measurement before treatment (p> 0.05). Icon resin infiltrant improved the color of WSLs significantly immediately after its application, giving the lowest ΔE value (3.00 ± 0.59), when compared to other treatments (p< 0.001). There were no significant changes in ΔE (p> 0.05) for all groups during the follow up intervals (one month, three and six months after treatments application). Conclusion: Resin infiltrant can improve the color of WSLs and restore the natural appearance of enamel better than nano-HA toothpaste and microabrasion.

RESUMO Objetivo: avaliar qualitativamente e quantitativamente os efeitos nas mudanças e estabilidade da cor de lesões de mancha branca (LMBs), após tratamento com infiltração de resina, em comparação aos tratamentos com pasta de dentes com nanopartículas de hidroxiapatita (Nano-HA) e com microabrasão. Métodos: As LMBs foram criadas artificialmente em 60 superfícies de esmalte dentário de pré-molares humanos e aleatoriamente divididas em quatro grupos (n=15, cada): pasta de dentes Nano-HA, microabrasão (Opalusture), tratamento com infiltração de resina (Icon) e saliva artificial (grupo controle). A mudança de cor (ΔE) de cada espécime foi aferida com um espectrofotômetro odontológico (Vita Easyshade) em diferentes tempos: início do estudo, após a criação das LMBs, após a aplicação dos tratamentos, um mês, três meses e seis meses após a aplicação dos tratamentos. Resultados: Os valores de ΔE não diferiram significativamente entre os quatro grupos ao início do estudo (p > 0,05). A infiltração com resina Icon melhorou significativamente a coloração das LMBs imediatamente após a sua aplicação, com o menor valor de ΔE (3,00 ± 0,59), quando comparada às outras modalidades de tratamento (p < 0,001). Não houve mudanças significativas nos valores de ΔE (p > 0,05) em qualquer um dos grupos durante os intervalos de acompanhamento (um mês, três meses e seis meses após a aplicação do tratamento). Conclusão: A infiltração de resina é capaz de melhorar a coloração das LMBs e restaurar a aparência natural do esmalte de forma superior à pasta de dentes com Nano-HA e à microabrasão.

The impact of silver nanoparticles integration on biofilm formation and mechanical properties of glass ionomer cement.

OBJECTIVES: To study the effect of silver nanoparticles incorporation to glass ionomer cement (GIC) on the Staphylococcus aureus biofilm in terms of bacterial growth and evaluate the incorporating effect on hardness and compressive strength. METHODS: Silver nanopowder was added in concentration 0, 1, 3, and 5 wt% to the conventional powder of GIC Fuji IX GP and then the powder is added to the liquid and mixed together with the recommended Powder/liquid ratio of 3.6:1 g. One hundred and twenty disc and cylindrical-shaped specimens were prepared using teflon molds. The specimens were put in tissue culture plate wells contained S. aureus in brain-heart infusion broth. The plate was incubated at 37°C for 24 h. Specimens were then washed, fixed, dehydrated, and air dried. The spatial distribution of biofilm was examined via scanning electron microscope. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were also evaluated. After setting, the specimens were stored in distilled water for 24 h before testing for microhardness and compressive strength. RESULTS: Scanning electron photomicrographs of biofilm formed on the control GIC, showed a consistent biofilm with a thick sheet of cells, whereas those formed were less dense at 3 wt% and below the detection limit at 5 wt% silver nanoparticles. MIC and MBC of S. aureus were 25 and 50 µg/mL, respectively. The microhardness and compressive strength values of tested groups showed a nonsignificant decrease from the control group, P = .58 and .82, respectively. CONCLUSION: Incorporation of silver nanoparticles with GIC can limit S. aureus biofilm formation with an insignificant effect on mechanical properties and noticeable influence on its coloration, which restrict its usage in areas where esthetic is not of major concern. CLINICAL SIGNIFICANCE: As the modification of GIC with silver nanoparticles improved the antibiofilm properties without altering its mechanical properties, it could be used as a restoration of root carious lesion mainly in nonesthetic areas, a base under composite restorations in deep posterior cavities and as a core material in caries susceptible patients.

Remineralizing effect of cold plasma and/or bioglass on demineralized enamel.

This study investigated the combining effect of cold plasma and bioglass-phosphoric acid paste on demineralized enamel. Fifty bovine incisors' enamel specimens were challenged by a demineralization solution of pH 4.47 for 72 h. Specimens were divided into five groups: (I) Control, demineralized enamel (C); (II) Demineralized enamel treated with fluoride varnish (F); (III) Cold plasma application to demineralized enamel (P); (IV) Demineralized enamel treated with bioglass paste (B); (V) Application of bioglass paste to cold plasma-treated demineralized enamel (PB). Specimens were then immersed in remineralizing solution for 24 h, before being examined with micro-computed tomography (micro-CT), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and cross-sectional micro-hardness measurement. The results showed that; treating demineralized enamel with cold plasmas before bioglass application ensued a significant high mineral volume recovery and micro-hardness of demineralized region. It can be concluded that cold plasmas may improve the remineralization of bioglass on demineralized enamel.

In vitro study of the potential protection of sound enamel against demineralization.

BACKGROUND: The objective of this study was to study the potential protection effect of different treatments against sound enamel demineralization around orthodontic brackets. METHODS: This is an in vitro randomized controlled study; artificial enamel demineralization of human premolars was created and compared with reference to control. The three materials used for enamel treatment were resin infiltrate (ICON), fluoridated varnish (Clinpro), and the self-etch primer system (Transbond Plus Self-Etch Primer). Fifty premolars divided equally into five groups were included in the study for quantitative surface micro-hardness assessment using a micro-hardness tester (MHT). Qualitative assessment of the enamel demineralization with a polarized light microscope (PLM) was also used. Enamel was demineralized by subjecting the specimens to cycling between artificial saliva solution and a demineralizing solution for 21 days. RESULTS: The mean Vickers hardness in kgf/mm(2) was as follows: intact enamel = 352.5 ± 13.8, demineralized enamel = 301.6 ± 34.0, enamel treated with Clinpro = 333.6 ± 18.0, enamel treated with SEP = 370.7 ± 38.8, and enamel treated with ICON = 380.5 ± 53.8. CONCLUSIONS: ICON, Clinpro, and Transbond Plus Self-Etch Primer (TPSEP) increased enamel resistance to demineralization. Attempting to protect the enamel around the orthodontic brackets could be done by applying a preventive material before bonding, if not compromising the bond strength, the orthodontic brackets.

Assessment of anodized titanium implants bioactivity.

OBJECTIVES: This study was conducted to create nanostructured surface titanium implants by anodic oxidation process aiming to bring out bioactivity and to assess the resultant bioactivity both in vitro and in vivo. MATERIALS AND METHODS: An economic protocol was used to apply anodic spark discharge and create surface nanoporosities on grade II commercially pure titanium (cpTi). The in vitro investigation included morphology, surface chemical analysis, roughness and crystalline structure of titanium oxide (TiO2) film prepared. Assessment of the bioactivity was carried out by immersing the specimens in simulate body fluid (SBF) and investigating the surface-deposited layer. The in vivo investigation was conducted by surgically placing the anodized implants into rabbits tibia for different healing periods. Then biomechanical evaluation was performed to verify the effect of treatments on the interface resistance to shear force. Routine histological analysis was performed to evaluate the bone tissue reactions to anodized implants. RESULTS: Anodization of titanium implants produced morphological changes, raised the percentage of oxygen in the TiO2 layer, increased surface area and roughness of implants remarkably, and modified the crystallinity of the film. The in vitro assessments of bioactivity showed that a layer of calcium phosphate was precipitated on the titanium surfaces 7 days after soaking into SBF. The implant-bone interface resistance to shear force was enhanced at 2-week healing period. This was confirmed by histological findings. CONCLUSION: Nanostructured surface titanium implants could be prepared by anodic oxidation with resultant accelerated bioactivity that may be recommended for early loading.