Tuning Nano-Amorphous Calcium Phosphate Content in Novel Rechargeable Antibacterial Dental Sealant

Maria Ibrahim,Thomas Oates,Yousif Al-Dulaijan,Hockin Xu,Michael Weir,Faisal Alqarni,Mary Melo

doi:10.3390/ma11091544

Abstract

Dental sealants with antibacterial and remineralizing properties are promising for caries prevention among children and adolescents. The application of nanotechnology and polymer development have enabled nanoparticles of amorphous calcium phosphate (NACP) and dimethylaminohexadecyl methacrylate (DMAHDM) to emerge as anti-caries strategies via resin-based dental materials. Our objectives in this study were to (1) incorporate different mass fractions of NACP into a parental rechargeable and antibacterial sealant; (2) investigate the effects on mechanical performance, and (3) assess how the variations in NACP concentration would affect the calcium (Ca) and phosphate (PO4) ion release and re-chargeability over time. NACP were synthesized using a spray-drying technique and incorporated at mass fractions of 0, 10, 20 and 30%. Flexural strength, flexural modulus, and flowability were assessed for mechanical and physical performance. Ca and PO4 ion release were measured over 70 days, and three ion recharging cycles were performed for re-chargeability. The impact of the loading percentage of NACP upon the sealant’s performance was evaluated, and the optimized formulation was eventually selected. The experimental sealant at 20% NACP had flexural strength and flexural modulus of 79.5 ± 8.4 MPa and 4.2 ± 0.4 GPa, respectively, while the flexural strength and flexural modulus of a commercial sealant control were 70.7 ± 5.5 MPa (p > 0.05) and 3.3 ± 0.5 GPa (p < 0.05), respectively. A significant reduction in flow was observed in the experimental sealant at 30% NACP (p < 0.05). Increasing the NACP mass fraction increased the ion release. The sealant formulation with NACP at 20% displayed desirable mechanical performance and ideal flow and handling properties, and also showed high levels of long-term Ca and PO4 ion release and excellent recharge capabilities. The findings provide fundamental data for the development of a new generation of antibacterial and rechargeable Ca and PO4 dental sealants to promote remineralization and inhibit caries.

Highlights

Dental caries is still a highly prevalent oral disease worldwide despite the various approaches that have been used to prevent it [1,2]
The present study reports the development of new antibacterial resin-based sealants that include different fractions of nanoparticles of amorphous calcium phosphate (NACP)
Three recharge/re‐release cycles were performed, and cycle diagram displayed the ion re-release from the exhausted and recharged NACP-containing each re‐release was measured for days

Summary

Introduction

Dental caries is still a highly prevalent oral disease worldwide despite the various approaches that have been used to prevent it [1,2]. These approaches include fluoride exposure, sugar intake control, brushing and dental sealants [3]. Dental sealants help prevent caries in pits and fissures of primary and permanent teeth, acting as a physical barrier for food accumulation and bacterial growth [4]. Findings have shown an increase in dental resin-based sealants failures due to bacterial colonization under the restored fissures, thereby, initiating and progressing the carious lesion beneath the sealant [4]

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