Table 2.

Nanoparticles used in nanocomposites for dental application.

Nanoparticle	Purpose of Use	Advantages	Toxicity	References
Carbon nanotubes	Coating of the teeth surface, teeth filling	Large surface area, adheres easily to the tooth surfaces and to the surfaces of dentin and cementum, bring active agents to live cells	Blocks potassium channels, accumulation in the hippocampus which induces oxidative stress, increased ROS factors, increased apoptosis factor	[29,117,123]
Graphene	Teeth coating, biofilm reduction, suitable for implantation	Treat bacterial biofilm, cost effectiveness, low dentistry form a uniform crystal lattice, fracture resistant	Toxicity depends on purity, shape, size and oxidative state,	[29,117,124]
Hydroxyapatite	Reduce dental hypersensitivity, retard auxiliary demineralisation, act as cavity filler, repairment of enamel surface, promotion osteoconduction	HA particles can easily integrate into the dental tubules, similar composition with teeth and bone, adsorbed to the enamel of the teeth, biocompatible, protect the teeth by making a film of artificial enamel around the tooth, reform periodontal shortcomings	Particles travelled to and dispersed into lungs, spleen and liver by blood, the inflammatory response, signalling pathway, induce oxidative stress,	[29,124,125]
Halloysite	Drug delivery, promotion attachment and proliferation of human dental stem cells, tissue engineering, scaffolds	Significant adsorption and loading capacities, improving mechanical properties, antibacterial, biocompatible, haemocompatible, sustained release of therapeutic agents, increased water adsorption and degradation rate	No toxic effects in recent studies	[126,127]
Zirconia	Reduces bacterial adhesion to the tooth surface, effective polishing agent, provide protection against dental carries	Similar mechanical properties and colour to those of a tooth, sensible biocompatibility, have low cytotoxicity, high fracture resistance	Significant DNA damage in human T-cells, induce apoptosis, inhibition of cell proliferation, nanoparticles can stop the cell cycle	[29,128]
Silica	Tooth polishing, an antibacterial agent, dental filling agent, prevents dental caries, to teat dental hypersensitivity	Biocompatible, low density, significant adsorption ability, low toxic effect, effective cost, reduces roughness of teeth surface (polishing agent)	Ability to induce silicosis, cytotoxicity, genotoxicity, possibility to induce oxidative stress, mediate apoptosis, g	[29]
Titania	Dental implants	Long-term effect on dental implants, surface modification—less bacterial adhesion, improved hardness, enhance the bone grow, protein adsorption and cell adhesion	Increased ROS factors, increased oxidative stress, genotoxicity, induce cellular apoptosis, increased inflammatory responses	[13,29,123,124,128]
Silver	Antimicrobial agent, dental implants, dental prosthetics, dental restorative material	Decrease bacterial colonisation, increases oral health, long-term antibacterial activity	Reduces mitochondrial viability, increased LDH release, increased ROS, up-regulated Bax protein expression, changes in astrocyte morphology, acute calcium response, induce apoptosis of lung cellular, increased cardiocyte deformity and lipid peroxidation, decreased levels of GSH, SOD and CAT, increased oxidative stress, increased release of inflammatory mediators in liver, inhibits mitochondrial ATP-ase in spleen	[13,29,117,123,124,128]