Antibacterial and Bonding Properties of Universal Adhesive Dental Polymers Doped with Pyrogallol.

Naji Kharouf,Davide Mancino,Louis Hardan,Youri Arntz,Hamdi Jmal,Salvatore Sauro,Vincent Ball,Federico Foschi,Rim Bourgi,Ammar Eid,Youssef Haikel

doi:10.3390/polym13101538

Abstract

This study investigated the antibacterial activity, bond strength to dentin (SBS), and ultra-morphology of the polymer–dentin interface of experimental adhesive systems doped with pyrogallol (PY), which is a ubiquitous phenolic moiety that is present in flavonoids and polyphenols. A universal adhesive containing 4-META and 10-MDP was used in this study. PY behaves as an antioxidant and anti-cancerogenic agent and it was incorporated into the adhesive at different concentrations (0.5 and 1 wt.%). The antibacterial activity and SBS were analyzed and the results were statistically analyzed. The ultra-morphology of the polymer–dentin interface was assessed using scanning electron microscopy (SEM). At 24 h, a lower antibacterial activity was observed for the control adhesive compared to those with 0.5% and 1% PY. No difference was seen in SBS between the three groups at 24 h. After 6 months, the SBS of the 0.5% PY adhesive was significantly lower than the other tested adhesives. The specimens created with 1% PY adhesive presented a higher bond strength at six months compared with that found at 24 h. No morphological differences were found at the polymer–dentin interfaces of the tested adhesives. Pyrogallol may be incorporated into modern universal adhesive systems to preserve the polymer–dentin bonding interface and confer a certain degree of antibacterial activity.

Highlights

Despite novel technologies and constant developments in polymer chemistry, there is still a lack of information regarding the bonding performance of modern universal adhesive systems [1]
The agar diffusion tests showed a prominent antibacterial activity of the adhesive doped with 1% PY against S. mutans, with inhibition zones of 5 ± 1 mm after 24 h of incubation
The Direct Contact Test (DCT) showed that the adhesive doped with 1% PY killed 94% of S. mutans when compared with the control group (Figure 3b), whilst the adhesive loaded with 0.5% PY destroyed 85% of the S.mutans bacteria

Summary

Introduction

Despite novel technologies and constant developments in polymer chemistry, there is still a lack of information regarding the bonding performance of modern universal adhesive systems [1] These types of adhesive systems represent an advanced choice for dental practitioners, as they can be used in self-etch, etch-and-rinse, or a selective enamel-etching mode [2,3]. Adequate bond strength to dentin is generally immediately achieved, whereas issues of longevity related to nanoleakage at the polymer–dentin interface still characterize modern adhesive systems [7] Such a compromised long-term performance is the result of a complex adhesive composition that is characterized by hydrophilic and hydrophobic components that are all placed in a simplified single-bottle system [8,9]. The incorporation of the antibacterial agents, such as quaternary ammonium methacrylate [12], methacryloyloxydodecylpyridinium bromide (MDPB) [13], dimethylaminododecyl methacrylate (DMADDM) [14], chlorhexidine [15], or silver nanoparticles in dental adhesives [16] could provide a new perspective to combat such a recurring clinical challenge [17]

Methods

Results

Discussion

Conclusion