Enhanced Delivery of F⁻, Ca²⁺, K⁺, and Na⁺ Ions into Enamel by Electrokinetic Flows

Abstract

As the outermost layer of the tooth crown, dental enamel is the most mineralized tissue in mammals, consisting of hydroxyapatite crystallites separated by long and narrow nanochannels. A major challenge in dentistry is how various molecules can be infiltrated into these nanopores in an efficient and controlled way. Here we show a robust method to transport various ions of interest, such as fluoride (F −), potassium (K +), calcium (Ca ++), and sodium (Na +), into these nanopores by electrokinetic flows. It is verified by fluorescence microscopy, laser-scanning confocal microscopy, mass spectrometry, and ion selective electrode technique. Different ions are demonstrated to infiltrate through the entire depth of the enamel layer (~1 mm), which is significantly enhanced penetration compared with diffusion-based infiltration. Meanwhile, transport depth and speed can be controlled by infiltration time and applied voltage. This is the first demonstration of reliably delivering both anions and cations into the enamel nanopores. This technique opens opportunities in caries prevention, remineralization, tooth whitening, and nanomedicine delivery in clinical dentistry, as well as other delivery challenges into various biomaterials such as bones.

Drug Delivery (Nano)Platforms for Oral and Dental Applications: Tissue Regeneration, Infection Control, and Cancer Management

“…By applying an electric current, the ions are transferred from the left reservoir into the right reservoir by infiltrating into the enamel non‐channels. [ 122 ] In another study, CPP‐ACP nanocomplexes were coupled with stannous fluoride to increase the stability of the nanocomplexes and ion release efficiency for the treatment of dental caries (Figure 10B). [ 119 ]…”

“…Reproduced with permission. [ 122 ] Copyright 2019, Springer, B) CPP‐ACP nanocomplex coupled with SnF 2 . CPP: casein phosphopeptide, ACFP: amorphous calcium fluorophosphate, SnF 2 : stannous fluoride.…”

“…A) Nanofluidic transport by electrokinetic flow. Reproduced with permission [122]. Copyright 2019, Springer, B) CPP-ACP nanocomplex coupled with SnF 2 .…”

Biomimetic mineralisation systems for in situ enamel restoration inspired by amelogenesis

“…Rods and IR represent for enamel rod and inter-rod, respectively. E, F Enamel rods with different orientations can be repaired [7] drilling holes for the treatment of initial-stage and moderate caries lesions [77,[80][81][82] Reinomiva, a King's College London dental spinout company, formed a commercialised method that utilises iontophoresis, known as electrically accelerated and enhanced remineralisation (EAER) [82]. The basic steps of EAER are as follows.…”

“…Iontophoresis is beneficial for accelerating and enhancing the remineralisation of enamel after etching [ 78 , 79 ]. Compared with diffusion alone, electrically accelerated ions flow delivers CaP ions into enamel sections to significantly greater depths (~1 mm) and does not require drilling holes for the treatment of initial-stage and moderate caries lesions [ 77 , 80 – 82 ] Reinomiva, a King’s College London dental spinout company, formed a commercialised method that utilises iontophoresis, known as electrically accelerated and enhanced remineralisation (EAER) [ 82 ]. The basic steps of EAER are as follows.…”