Evaluating the Microshear Bond Strength and Microleakage of Flowable Composites Containing Zinc Oxide Nano-particles

Assessing the physico-mechanical, anti-bacterial, and anti-demineralization properties of orthodontic resin composite containing different concentrations of photoactivated zinc oxide nanoparticles on Streptococcus mutans biofilm around ceramic and metal orthodontic brackets: An ex vivo study

BACKGROUND AND PURPOSE

The aim of this study was to evaluate the physico-mechanical, anti-bacterial, and anti-demineralization properties of orthodontic resin composite containing photoactivated zinc oxide nanoparticles (ZnONPs) on Streptococcus mutans biofilm around ceramic and metal brackets.

MATERIAL AND METHODS

Following the minimum inhibitory concentration (MIC) determination for ZnONPs, shear bond strength (SBS) was tested for composites containing different concentrations of ZnONPs. The chosen concentration was used to evaluate the microleakage, anti-bacterial, and anti-demineralization properties.

RESULTS

Adding 50μg/mL of ZnONPs to the orthodontic composite did not negatively affect its physico-mechanical properties. ZnONPs (50μg/mL)-mediated aPDT and 0.2% chlorhexidine significantly (P=0.000) reduced S. mutans biofilms compared to the phosphate-buffered saline (PBS) groups (metal/PBS=7.47±0.7×106, and ceramic/PBS=7.47±0.7×106), with the lowest colony count observed in these groups (metal/chlorhexidine=1.06±0.4×105, ceramic/chlorhexidine=1±0.2×105, metal/ZnONPs-mediated aPDT=1.33±0.3×105, and ceramic/ZnONPs-mediated aPDT=1.2±0.3×105). Sodium fluoride varnish and ZnONPs-mediated aPDT showed the highest efficacy in anti-demineralization and significantly improving the enamel surface microhardness compared to the artificial saliva, especially in ceramic bracket groups (524.17±42.78N and 441.00±29.48N, 394.17±46.83N, P=0.000, and P=0.003, respectively).

CONCLUSION

ZnONPs (50μg/mL)-mediated aPDT effectively inhibited S. mutans biofilm and promoted anti-demineralization without adverse effects on the physico-mechanical properties of the composite resin. These results suggest the potential of this method in preventing white spot lesions during orthodontic treatment.

Evaluation and comparison of the effect of incorporating zinc oxide and titanium dioxide nanoparticles on the bond strength and microleakage of two orthodontic fixed retainer adhesives

BACKGROUND

An adhesive with both proper mechanical and antimicrobial properties seems to be beneficial. We aimed to investigate the effect of zinc oxide (ZnO) and titanium dioxide (TiO₂) nanoparticles (NPs) on bond strength and microleakage of two different fixed retainer adhesives.

METHODS

In this in vitro experimental study, 168 extracted human incisors were randomly divided into six groups of 28 (eight double-tooth specimens for the bond strength test and 12 specimens for the microleakage test). In three groups: Transbond XT (3M Unitek, Monrovia, CA) without NPs, with 1% ZnO NPs and with 1% TiO2 NPs were applied. The other three groups included Ortho Connect Flow (GC orthodontics, Tokyo, Japan) composite with the same order to bond a 0.175-inch multistrand wire to the lingual surfaces of the teeth. The bond strength was measured using the Universal Testing Machine, and the adhesive remnant index was reported using a stereomicroscope (Nikon, SMZ800, Tokyo, Japan). The dye-penetration method was used to determine the microleakage.

RESULTS

For bond strength, there was no significant difference among groups. For microleakage, there was no significant difference between GC and Transbond XT groups. However, in subgroups of Transbond XT, the addition of TiO₂ NPs increased the microleakage significantly in comparison with ZnO and control groups (P = 0.011). There was no significant statistical difference between the groups in terms of residual adhesives (P = 0.166).

CONCLUSIONS

Through the incorporation of 1% TiO₂ and ZnO NPs into the fixed retainer adhesive, the bond strength was maintained within the clinically acceptable range. The addition of TiO2 NPs to Transbond XT significantly increased the percentage of microleakage.

Zinc Oxide Nanoparticles: A Review on Its Applications in Dentistry

Nanotechnology in modern material science is a research hot spot due to its ability to provide novel applications in the field of dentistry. Zinc Oxide Nanoparticles (ZnO NPs) are metal oxide nanoparticles that open new opportunities for biomedical applications that range from diagnosis to treatment. The domains of these nanoparticles are wide and diverse and include the effects brought about due to the anti-microbial, regenerative, and mechanical properties. The applications include enhancing the anti-bacterial properties of existing restorative materials, as an anti-sensitivity agent in toothpastes, as an anti-microbial and anti-fungal agent against pathogenic oral microflora, as a dental implant coating, to improve the anti-fungal effect of denture bases in rehabilitative dentistry, remineralizing cervical dentinal lesions, increasing the stability of local drug delivery agents and other applications.

An overview of recent progress in dental applications of zinc oxide nanoparticles

Nanotechnology is an emerging field of science, engineering, and technology concerning the materials in nanoscale dimensions. Several materials are used in dentistry, which can be modified by applying nanotechnology. Nanotechnology has various applications in dentistry to achieve reliable treatment outcomes. The most common nanometals used in dental materials are gold, silver, copper oxide, magnesium oxide, iron oxide, cerium oxide, aluminum oxide, titanium dioxide, and zinc oxide (ZnO). ZnO nanoparticles (NPs), with their unparalleled properties such as high selectivity, enhanced cytotoxicity, biocompatibility, and easy synthesis as important materials were utilized in the field of dentistry. With this background, the present review aimed to discuss the current progress and gain an insight into applications of ZnO NPs in nanodentistry, including restorative, endodontic, implantology, periodontal, prosthodontics, and orthodontics fields.

Review of nano-technology applications in resin-based restorative materials

OBJECTIVE

Nanotechnology has progressed significantly and particles as small as 3 nm are being employed in resin-based restorative materials to improve clinical performance. The goal of this review is to report the progress of nanotechnology in Restorative Dentistry by reviewing the advantages, limitations, and applications of resin-based restorative materials with nanoparticles.

MATERIALS AND METHODS

A literature review was conducted using PubMed/Medline, Scopus and Embase databases. In vitro, in vivo and in situ research studies published in English between 1999 and 2020, and which focused on the analysis of resin-based restorative materials containing nanoparticles were included.

RESULTS

A total of 140 studies were included in this review. Studies reported the effect of incorporating different types of nanoparticles on adhesive systems or resin composites. Mechanical, physical, and anti-bacterial properties were described. The clinical performance of resin-based restorative materials with nanoparticles was also reported.

CONCLUSIONS

The high surface area of nanoparticles exponentially increases the bioactivity of materials using bioactive nanofillers. However, the tendency of nanoparticles to agglomerate, the chemical instability of the developed materials and the decline of rheological properties when high ratios of nanoparticles are employed are some of the obstacles to overcome in the near future.

CLINICAL SIGNIFICANCE

In spite of the recent advancements of nanotechnology in resin-based restorative materials, some challenges need to be overcome before new nano-based restorative materials are considered permanent solutions to clinical problems.

Nanometals in Dentistry: Applications and Toxicological Implications-a Systematic Review

Nanotechnology is a vital part of health care system, including the dentistry. This branch of technology has been incorporated into various fields of dentistry ranging from diagnosis to prevention and treatment. The latter involves application of numerous biomaterials that help in restoration of esthetic and functional dentition. Over the past decade, these materials were modified through the incorporation of metal nanoparticles (NP) like silver (Ag), gold (Au), titanium (Ti), zinc (Zn), copper (Cu), and zirconia (Zr). They enhanced antimicrobial, mechanical, and regenerative properties of these materials. However, lately, the toxicological implications of these nanometal particles have been realized. They were associated with cytotoxicity, genotoxicity altered inflammatory processes, and reticuloendothelial system toxicity. As dental biomaterials containing metal NPs remain functional in oral cavity over prolonged periods, it is important to know their toxicological effects in humans. With this background, the present systematic review is aimed to gain an insight into the plausible applications and toxic implications of nano-metal particles as related to dentistry.