Glass ionomer cements with milled, dry chlorhexidine hexametaphosphate filler particles to provide long-term antimicrobial properties with recharge capacity

Characterization of polymethylmethacrylate microspheres loaded with silver and doxycycline for dental materials applications

OBJECTIVES

The manufacturing of polymethylmethacrylate(PMMA) microspheres loaded with doxycycline(DOX) and/or silver sulfate(Ag₂SO₄) to be incorporated into glass ionomer cement(GIC).

METHODS

PMMA microspheres were manufactured with Ag₂SO₄(1-5%) and/or DOX(5-15%). Particle size, encapsulation efficiency and drug release were measured by light microscope, ICP, and HPLC. Microspheres were added to a dental GIC(20%w/w). Drug release and DTS were investigated. Minimum inhibitory concentration and antibacterial effects of PMMA microspheres into GIC materials were tested.

RESULTS

The median diameter of 50 µm was obtained for microspheres. DOX was encapsulated at an efficiency of 8.3% using a theoretical loading of 15%DOX + 5%Ag₂SO₄. The Ag₂SO₄ encapsulation efficiency was 0.63% using a theoretical loading of 5%AgSO₄. All groups showed burst release within the first day and continued released up to 15 days, with 60-83% of DOX and approximately 30% of silver. For GIC, approximately 15% of DOX and 0.18% of silver were released in a 7-day period. Microbiological results showed an antimicrobial effect against S. mutans when the lead formulation of microspheres was added. The DTS was reduced by the inclusion of microspheres.

SIGNIFICANCE

PMMA microspheres containing DOX and Ag₂SO₄ offer a sustained antimicrobial activity for dental applications and promising potential for the biomedical field.

Alkali-Treated Alumina and Zirconia Powders Decorated with Hydroxyapatite for Prospective Biomedical Applications

The alumina and zirconia surfaces were pretreated with chemical etching using alkaline mixtures of ammonia, hydrogen peroxide and sodium hydroxide, and followed with application of the powder layer of Ca-deficient hydroxyapatite (CDH). The influence of etching bath conditions time and concentration on surface development, chemical composition and morphology of medicinal ceramic powders were studied. The following analyses were performed: morphology (scanning electron microscopy), phase composition (X-ray diffraction analysis), changes in binding interactions and chemical composition (FT-Infrared and Energy dispersive spectroscopies). Both types of etchants did not expose the original phase composition changes or newly created phases for both types of ceramics. Subsequent decoration of the surface with hydroxyapatite revealed differences in the morphological appearance of the layer on both ceramic surfaces. The treated zirconia surface accepted CDH as a flowing layer on the surface, while the alumina was decorated with individual CDH aggregates. The goal of this study was to focus further on the ceramic fillers for polymer-ceramic composites used as a biomaterial in dental prosthetics.

Antimicrobial Efficacy of Glass Ionomer Cement in Incorporation with Biogenic Zingiber officinale Capped Silver-Nanobiotic, Chlorhexidine Diacetate and Lyophilized Miswak

In the present study, Zingiber officinale is used for the synthesis of Zingiber officinale capped silver nanoparticles (ZOE-AgNPs) and compares the antimicrobial efficacy and compressive strength of conventional glass ionomer cement (GIC) combined with ZOE-AgNPs, lyophilized miswak, and chlorhexidine diacetate (CHX) against oral microbes. Five groups of the disc-shaped GIC specimens were prepared. Group A: lyophilized miswak and GIC combination, Group B: ZOE-AgNPs and GIC combinations, Group C: CHX and GIC combination, Group D: ZOE-AgNPs + CHX + GIC; Group E: Conventional GIC. Results confirmed the successful formation of ZOE-AgNPs that was monitored by UV-Vis sharp absorption spectra at 415 nm. The X-ray diffractometer (XRD) and transmission electron microscope (TEM) results revealed the formation of ZOE-AgNPs with a mean size 10.5-14.12 nm. The peaks of the Fourier transform infrared spectroscopy (FTIR) were appearing the involvement of ZOE components onto the surface of ZOE-AgNPs which played as bioreducing, and stabilizing agents. At a 24-h, one-week and three-week intervals, Group D showed the significantly highest mean inhibitory zones compared to Group A, Group B, and Group C. At microbe-level comparison, Streptococcus mutans and Staphylococcus aureus were inhibited significantly by all the specimens tested except group E when compared to Candida albicans. Group D specimens showed slightly higher (45.8 ± 5.4) mean compressive strength in comparison with other groups. The combination of GIC with ZOE-AgNPs and chlorhexidine together enhanced its antimicrobial efficacy and compressive strength compared to GIC with ZOE-AgNPs or lyophilized miswak or chlorhexidine combination alone. The present study revealed that The combination of GIC with active components of ZOE-AgNPs and chlorhexidine paves the way to lead its effective nano-dental materials applications.

A novel chlorhexidine-hexametaphosphate coating for titanium with antibiofilm efficacy and stem cell cytocompatibility

Dental implants are an increasingly popular way to replace missing teeth. Whilst implant survival rates are high, a small number fail soon after placement, with various factors, including bacterial contamination, capable of disrupting osseointegration. This work describes the development of chlorhexidine-hexametaphosphate coatings for titanium that hydrolyse to release the antiseptic agent chlorhexidine. The aim was to develop a coating for titanium that released sufficient chlorhexidine to prevent biofilm formation, whilst simultaneously maintaining cytocompatibility with cells involved in osseointegration. The coatings were characterised with respect to physical properties, after which antibiofilm efficacy was investigated using a multispecies biofilm model, and cytocompatibility determined using human mesenchymal stem cells. The coatings exhibited similar physicochemical properties to some implant surfaces in clinical use, and significantly reduced formation of multispecies biofilm biomass up to 72 h. One coating had superior cytocompatibility, with mesenchymal stem cells able to perform normal functions and commence osteoblastic differentiation, although at a slower rate than those grown on uncoated titanium. With further refinement, these coatings may have application in the prevention of bacterial contamination of dental implants at the time of surgery. This could aid a reduction in rates of early implant failure.

Comparative Evaluation of Antibacterial Effect of GIC Containing Chlorhexidine and Miswak on Streptococcus mutans and Streptococcus sobrinus in Early Childhood Caries Children: A PCR Study

Background and aim

The therapeutic procedures used in the treatment of caries do not always eliminate all the microorganisms. Persisting cariogenic bacteria can cause recurrent caries and failure of restoration. Incorporation of an antimicrobial agent in the restorative material may be of paramount significance. The purpose of this study was to evaluate and compare the antibacterial effect of glass ionomer cement (GIC) containing CHX and miswak extract on Streptococcus mutans and Streptococcus sobrinus in ECC children using polymerase chain reaction (PCR).

Materials and methods

Forty-five children with ECC in the age-group 3–6 years were selected. The children were randomly allocated into three groups. Supragingival plaque samples (S1) were collected from sound buccal or labial surfaces of primary teeth. Cavity preparation was done and the teeth were restored according to the group to which the child had been allotted. The second plaque sample (S2) was collected 1 month and the final sample after 3 months of restoring all the decayed teeth. All the samples were sent for PCR analysis.

Results

Intergroup analysis was done using Kruskal–Wallis test followed by Mann–Whitney post hoc test showed statistically significant difference in S. mutans and S. sobrinus count between group I (CHX) and group III (control) and group II (miswak) and group III (control) but no statistically significant difference between group I (CHX) and group II (miswak) in S. mutans and S. sobrinus count.

Conclusion

1% chlorhexidine digluconate and aqueous extract of miswak are equally effective against S. mutans and S. sobrinus. Miswak can be used as an alternative herbal antimicrobial that can be incorporated in anhydrous GIC.

How to cite this article

Kalpavriksha AJ, Siddaiah SB, Bilichodmath S, et al. Comparative Evaluation of Antibacterial Effect of GIC Containing Chlorhexidine and Miswak on Streptococcus mutans and Streptococcus sobrinus in Early Childhood Caries Children: A PCR Study. Int J Clin Pediatr Dent 2021;14(2):229–234.

Antibacterial, biological, and physicochemical properties of root canal sealers containing chlorhexidine-hexametaphosphate nanoparticles

OBJECTIVE

The aim of this study was to evaluate the influence of the incorporation of chlorhexidine-hexametaphosphate nanoparticles (CHX-HMP NPs) on antibacterial, cytotoxic and physicochemical properties of AH Plus (AH), MTA Fillapex (MTA) and Pulp Canal Sealer (PCS).

METHODS

The NPs were synthesized and characterized by Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), zeta potential, Atomic Force Microscopy (AFM) and Energy-Dispersive X-ray Spectroscopy (EDS). The incorporation was made by weight, 2% and 5% of NPs. The antimicrobial activity, cytotoxicity, flow, radiopacity, setting time, solubility and pH were evaluated. The statistical analysis was performed by two-way analysis of variance test and Tukey post hoc test (P < 0.05).

RESULTS

SEM analysis showed the tendency for CHX-HMP NPs to cluster, the effective mean diameter measured by DLS: 169.39 nm and the zeta potential: -10.18 mV. The NPs were individually measured by AFM: 22.99-52.75 nm. EDS analysis identified the presence of C, N, O, Na, P, Cl. After incorporation: The Direct Contact Test showed an increase in the antimicrobial action of AH, PCS and MTA; the sealers showed a decrease in flow and at 24 h of immersion also an increase in solubility, but did not affect the radiopacity of the samples; AH setting time increased and MTA did not reach setting under any of the conditions tested. All samples showed a decrease in pH value as the immersion time progressed.

SIGNIFICANCE

The incorporation of NPs can improve the antimicrobial performance of endodontic sealers without impairing other biological and physicochemical properties.

Alginate films augmented with chlorhexidine hexametaphosphate particles provide sustained antimicrobial properties for application in wound care

All chronic wounds are colonised by bacteria; for some, colonisation progresses to become infection. Alginate wound dressings are used for highly exuding chronic wounds as they are very absorbent, taking up large quantities of exudate while maintaining a moist wound bed to support healing. Some alginate dressings are doped with antimicrobials, most commonly silver, but evidence regarding the efficacy of these is largely inconclusive. This manuscript describes the development and in vitro assessment of alginate materials doped with chlorhexidine hexametaphosphate (CHX-HMP), a sparingly soluble salt which when exposed to aqueous environments provides sustained release of the common antiseptic chlorhexidine. Comparator materials were a commercial silver alginate dressing material and an alginate doped with chlorhexidine digluconate (CHXdg). CHX-HMP alginates provided a dose-dependent CHX release which was sustained for over 14 days, whereas CHXdg alginates released limited CHX and this ceased within 24 h. CHX-HMP and silver alginates were efficacious against 5 major wound pathogens (MRSA, E. coli, P. aeruginosa, K. pneumoniae, A. baumannii) in a total viable count (TVC) and an agar diffusion zone of inhibition (ZOI) model. At baseline the silver alginate was more effective than the CHX-HMP alginate in the TVC assay but the CHX-HMP alginate was the more effective in the ZOI assay. After 7 days' artificial aging the CHX-HMP alginate was more effective than the silver alginate for four of the five bacteria tested in both assays. These materials may ultimately find application in the development of wound dressings for chronic wounds that provide sustained antimicrobial protection.