The development of drug-free therapy for prevention of dental caries

Abstract

Purpose: The purpose of this study was to develop a novel, drug-free therapy that can reduce the over-accumulation of cariogenic bacteria on dental surfaces.

Methods: We designed and synthesized a polyethylene glycol (PEG)-based hydrophilic copolymer functionalized with a pyrophosphate (PPi) tooth-binding anchor using "click" chemistry. The polymer was then evaluated for hydroxyapatite (HA) binding kinetics and capability of reducing bacteria adhesion to artificial tooth surface.

Results: The PPi-PEG copolymer can effectively inhibit salivary protein adsorption after rapid binding to an artificial tooth surface. As a result, the in vitro S. mutans adhesion study showed that the PPi-PEG copolymer can inhibit saliva protein-promoted S. mutans adhesion through the creation of a neutral, hydrophilic layer on the artificial tooth surface.

Conclusions: The results suggested the potential application of a PPi-PEG copolymer as a drug-free alternative to current antimicrobial therapy for caries prevention.

Figure 1

Synthesis of Dentotropic Click-PEG (PPi-PEG).

Figure 2

The binding kinetics of PPi-PEG copolymer to HA surface. HMLP, PPi-PEG copolymer with high MW and low pyrophosphate content; LMHP, PPi-PEG copolymer with low MW and high pyrophosphate content; HMHP, PPi-PEG copolymer with high MW and high pyrophosphate content; LMLP, PPi-PEG copolymer with low MW and low pyrophosphate content; Non-binding, control click-PEG copolymer which do not contain pyrophosphate. Data are presented as the mean ± SD, n=3. Asterisks indicate significant differences (P<0.05).

Figure 3

In vitro inhibition of salivary protein adsorption on HA disc surface by PPi-PEG copolymers. HMLP, PPi-PEG copolymer with high MW and low pyrophosphate content; LMHP, PPi-PEG copolymer with low MW and high pyrophosphate content; HMHP, PPi-PEG copolymer with high MW and high pyrophosphate content; LMLP, PPi-PEG copolymer with low MW and low pyrophosphate content; Non-binding, control click-PEG copolymer which do not contain pyrophosphate. Data are presented as the mean ± SD, n=3. Asterisks indicate significant differences (P<0.05).

Figure 4

In vitro inhibition of S. mutans adhesion on (A) clean HA disc surface; (B) saliva-coated HA disc surface. HMLP, PPi-PEG copolymer with high MW and low pyrophosphate content; LMHP, PPi-PEG copolymer with low MW and high pyrophosphate content; HMHP, PPi-PEG copolymer with high MW and high pyrophosphate content; LMLP, PPi-PEG copolymer with low MW and low pyrophosphate content; Non-binding, control click-PEG copolymer which do not contain pyrophosphate. Data are presented as the mean ± SD, n=3. Asterisks indicate significant differences (P<0.05).