Effect of fluoride iontophoresis on the microtensile bond strength between dentin and two adhesive systems

The effect of fluoride iontophoresis on seal ability of self-etch adhesive in human dentin in vitro

Background

Fluoride iontophoresis (FI) is a non-invasive method for the transfer of fluoride ions under electrical pressure into dental hard tissue. This study aimed to determine the effect of FI on the seal ability of self-etch adhesive in human dentin using dentin permeability test and scanning electron microscopy (SEM).

Methods

The experiments were divided into 2 series: series 1 was performed on 28 extracted intact third molars and series 2 was performed on 28 extracted carious third molars (ICDAS 4 and 5). In each series, 20 teeth were used for dentin permeability test and 8 teeth were used for SEM study. For dentin permeability test, the specimens were divided into dentin without FI (control) and dentin with FI (experimental) subgroups. Hydraulic conductance (HD) of dentin was measured before and after adhesive treatment, and calculated for the percentage decrease of HD in each subgroup. Two-way ANOVA and Tukey test were used for statistical analysis. SEM study was used to assess the seal ability of self-etch adhesive and penetration of fluoride ions into dentinal tubules.

Results

HD after self-etch adhesive treatment reduced by 57.75 ± 17.99% in intact dentin with FI, 46.60 ± 17.03% in intact dentin without FI, 45.00 ± 15.30% in caries affected dentin without FI, and 37.28 ± 14.72% in caries affected dentin with FI. There was no significant difference in percentage decrease of HD between dentin without FI and dentin with FI (P = 0.742); meanwhile, intact dentin with FI had significant greater percentage decrease than caries affected dentin with FI (P < 0.05). SEM findings showed FI produced more particle formation and deeper precipitation in intact dentin than those in caries affected dentin.

Conclusions

FI did not affect the seal ability of self-etch adhesive in human dentin when compared to without FI. However, FI could augment the seal ability of the self-etch adhesive in intact dentin better than that in caries affected dentin.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02146-w.

Onychomycosis: Current Understanding and Strategies for Enhancing Drug Delivery into Human Nail Tissue

BACKGROUND

Onychomycosis is by far the most common finger or toe nail fungal infectious disease caused by dermatophytes, non-dermatophytic molds or yeast. It accounts for 50% of the total nail disorders, and affects patients physically, socially, and psychologically and can seriously influence their quality of life.

OBJECTIVES

Oral antifungals are routinely used to treat the nail fungal disease; however oral therapy is associated with severe side effects and longer treatment times. In recent years, drug delivery directly into the nail or nail bed has gained attention and various topical products have been tested that can cure the disease when applied topically or transungually. Nevertheless, drug penetration into and through the nail is not straightforward and requires chemicals to improve its permeability or by applying physical stress to promote drug penetration into and through the nail. This lucid review presents an overview of various causes of onychomycosis, current therapeutic approaches, and efforts aimed at increasing the permeability of nails through various strategies such as chemical, physical and mechanical methods for permeation enhancement.

CONCLUSION

Various strategies have been proposed for the treatment of onychomycosis, however, much research into a more precise and effective therapy is still required.

Selected Medicines Used in Iontophoresis

Iontophoresis is a non-invasive method of systemic and local drug delivery using an electric field. Iontophoresis enables diffusion of the selected drug via skin, mucosa, enamel, dentin, and other tissues. The amount of delivered therapeutic molecules is about 10⁻2000 times greater than conventional forms of delivery. Among other fields, this method is used in dentistry, ophthalmology, otorhinolaryngology, and dermatology. According to related literature, the most important drugs studied or administered by iontophoresis are: Local anesthetics, opioids, steroids, non-steroidal anti-inflammatory drugs, antibacterial drugs, antifungal drugs, antiviral drugs, anticancer drugs, fluorides, and vitamins. The present review covers current available data regarding the selected medicines used in iontophoresis. Furthermore, indications and conditions of iontophoresis application are reviewed.

Onychomycosis: Potential of Nail Lacquers in Transungual Delivery of Antifungals

Onychomycosis constitutes the most common fungal infection of the nail (skin beneath the nail bed) that affects the finger as well as toe nails. It is an infection that is initiated by yeasts, dermatophytes, and nondermatophyte molds. Nail lacquers are topical solutions intended only for use on fingernails as well as toenails and have been found to be useful in the treatment of onychomycosis. Thus, in the present review an attempt has been made to focus on the treatment aspects of onychomycosis and the ungual delivery of antifungals via nail lacquer. Several patents issued on nail lacquer till date have also been discussed. Penetration efficiency was assessed by several researchers across the human nail plate to investigate the potentiality of nail lacquer based formulations. Various clinical trials have also been conducted in order to evaluate the safety and efficacy of nail lacquers in delivering antifungal agents. Thus, it can be concluded that nail lacquer based preparations are efficacious and stable formulations. These possess tremendous potential for clinical topical application to the nail bed in the treatment of onychomycosis.