# Antimicrobials in Dentistry
## 2 Antimicrobials Used in Dentistry  
The oral cavity encounters a host of microorganisms that cause biofilms to form, leading to plaque formation that subsequently results in tooth decay. Dental caries is a highly prevalent non-communicable disease that occurs when plaque-associated bacteria generate acid that causes damage to tooth tissue. Active dental caries irreversibly damage and eventually kill teeth; hence, combatting this disease has been one of the priorities in improving global oral health. Despite significant measures being implemented that range from preventive to restorative procedures, this disease continues to affect approximately a third of the world's population [7]. To prevent dental caries, it is vital to control the formation of oral microbial biofilms, and for dental restorations specifically it is important that it not only resists biofilm formation but is able to maintain tooth mineral and/or promote mineralisation [8]. Advances in the field of biomaterials have led to excellent materials that are clinically used to repair and restore the function of tooth tissue due to loss or disease. Among others, natural polymers such as chitosan, peptides and some biobased polyesters show promising potential for the reconstruction of damaged or lost tissue, especially when infections impair their regenerative processes [9]. However, the propensity of the formation of biofilms in the oral environment necessitates designing synthetic materials with complex functionalities such as antimicrobial and remineralising capacities. Since dental caries have been recognized as a disease induced by cariogenic bacteria, significant research has focused on developing restorative systems possessing antibacterial properties in dental materials science. Thus, controlling bacterial contamination around and beneath restorations is expected to decrease the risk of further demineralisation and cavitation and help prevent forming secondary caries [10; 11]. Many different approaches have been investigated to minimise the burden of the effects of oral biofilms, such as preventive measures including antibacterial agents in restorative systems, polymeric materials with antibacterial properties and their release. Preventive measures to improve general oral health that are commercially available range from fluoride-containing toothpastes, dentifrices and mouthwashes with antibacterial agents [12]. However, there are many different polymeric systems used in dentistry for the restoration of teeth that are affected by caries; therefore, significant research has focused on rendering these with antibacterial properties. Dental resin composite restorations are the most widely used restorative materials and are bonded to teeth using adhesive systems. The tooth tissue is prepared using an acid that demineralises it to render a porous structure that enables the interlocking of the resin either in the enamel etched pits or the exposed collagen lattice in dentine. The adhesive systems typically comprise photopolymerisable methacrylate monomers that are used following the preparation of the tooth surface. One of the main reasons for failure is the breakdown of the tooth-restorative adhesive interface, which can occur due to the hydrolytic cleavage of the bond, collagenolytic activity that destabilises the bond and ingress of salivary enzymes and microorganisms in micro-gaps formed at the interface leading to the formation of secondary caries due to bacterial activity [13; 14; 15]. Hence, research and clinical applications have focused on developing dental composites and adhesive systems that can reduce both recurrent caries and degradation of the adhesive interface [16; 17]. However, if the curious lesion is left untreated or the restoration of choice is unable to provide an effective seal against further bacterial ingress, the infection can persist to involve the dental pulp and the tooth's root canal system.