Conte, Raffaele (2018) ANTIMICROBIAL EFFECT OF NEW RESTORATIVE DENTAL MATERIAL INCORPORATING SILVER NANOPARTICLES. [Tesi di dottorato]

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Item Type: Tesi di dottorato
Lingua: English
Title: ANTIMICROBIAL EFFECT OF NEW RESTORATIVE DENTAL MATERIAL INCORPORATING SILVER NANOPARTICLES
Creators:
CreatorsEmail
Conte, Raffaeleraffaele.conte86@tiscali.it
Date: 9 December 2018
Number of Pages: 131
Institution: Università degli Studi di Napoli Federico II
Department: Neuroscienze e Scienze Riproduttive ed Odontostomatologiche
Dottorato: Medicina clinica e sperimentale
Ciclo di dottorato: 31
Coordinatore del Corso di dottorato:
nomeemail
Beguinot, Francescobeguino@unina.it
Tutor:
nomeemail
Rengo, SandroUNSPECIFIED
Date: 9 December 2018
Number of Pages: 131
Uncontrolled Keywords: Secondary Caries, LDH, Antimicrobial action
Settori scientifico-disciplinari del MIUR: Area 06 - Scienze mediche > MED/28 - Malattie odontostomatologiche
Date Deposited: 19 Dec 2018 15:22
Last Modified: 26 Jun 2020 20:29
URI: http://www.fedoa.unina.it/id/eprint/12528

Abstract

Secondary or recurrent caries are dental lesions originated at the margins of an existing restoration, and are considered the most common reason for restoration failure. Usually, these lesions are histologically similar to the primary caries and can be difficult to detect unless somewhat advanced, resulting in a considerable loss of tooth structure. Over the past decades, resin-based dental materials have been used in restorative dentistry for their excellent esthetics and improved mechanical performance. However, they represent potential sources of carbon and energy for microorganisms including oral bacteria and fungi residual in the dental cavity. In addition, cariogenic bacteria can infiltrate the restoration-tooth margins compromise the restoration’s longevity. Because caries at the restoration margins is a main reason for restoration failures, it would be highly desirable for the composite and bonding agent to possess antibacterial capabilities. Novel antibacterial dental materials were developed by introducing quaternary ammonium monomers, including 12-methacryloyloxydodecylpyridinium bromide (MDPB), dimethylaminohexadecyl methacrylate (DMAHDM), and dimethylaminododecyl methacrylate (DMADDM). These monomers can form covalent bonds with the polymer matrix and be immobilized in the resin-based materials, representing a non-released, contact-killing agent. Several other antimicrobial formulations were also developed, including a methacryloxylethylcetyl dimethyl ammonium chloride (DMAE-CB) containing adhesive, quaternary ammonium polyethylenimine (PEI) nanoparticles for antimicrobial dental composites, antibacterial glass ionomer cements, and antibacterial nanocomposites and bonding agents incorporating a quaternary ammonium dimethacrylate (QADM). Quaternary ammonium acrylate (QAM) resins possess positively-charged quaternary amine N+ which can interact with the negatively-charged membrane of bacteria, leading to membrane disruption and cytoplasm leakage. It is postulated that long-chained quaternary ammonium compounds can be especially effective by inserting into the bacterial membrane, resulting in physical disruption and bacteria death. Aside from the antibacterial monomers added to the resin matrix, an alternative approach is to add silver nanoparticles. Indeed, silver (Ag) is known for its antimicrobial activity against a diverse group of bacteria and has been used for many years as an antimicrobial substance in the medical field. Composite containing Ag particles with long-lasting antibacterial activity have been manufactured and observed to inhibit S. mutans growth . In addition, resins containing Ag nanoparticles were able to inhibit biofilm viability. Although the restorative materials had significant evolvement in the past few decades, the high rates of treatment failure suggest that the current restorative approaches are not yet optimized and have a potential for improvement. The aim of this work is to synthesize and evaluate new bioactive and antibacterial composite materials based on photo-activated Bis-GMA/TEGDMA matrix, containing an hydrotalcite-like compound intercalated with Ag nanoparticles as filler. We have obtained a dental resin with improved physical and biological properties and, in addition, able to release low amount of silver in a controlled and tunable way for a long period of time. In contrast to the conventional and resin-modified glass-ionomers, our CR-Agx were able to release silver ions when intraoral pH values drop below the critical pH of 5.5, counteracting the demineralization process of the tooth surface. The caries protective effect of these materials may be related to the material’s ability to release adequate amounts of silver ions for sustained periods of time and during acidic attack.

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