## 1 Introduction  
A biofilm is a sessile community of microbial cells immersed in a matrix composed of extracellular polymeric substances (EPSs) attached to the surface. EPSs consist of exopolysaccharide, lipids, proteins, and nucleic acids (eDNA and eRNA) and offer a functional environment and structural stability. Tolerance to immune cells and antimicrobials is enhanced by EPSs [1]. Dental plaque is a complex biofilm whose formation begins with the formation of the salivary pellicle and changes progressively; therefore, we can differentiate early and mature plaque, as well as subgingival and supragingival plaque [2]. Supragingival biofilm bacteria like _S. mutans_, _Actinomyces_ spp., and _Lactobacillus_ have the greatest influence on enamel and dentin demineralisation and ultimately caries formation [3]. Somesubgingival biofilm bacteria include _Actinomyces_ spp., _Tamerella forysthia_, and _Fusobacterium nucleatum_, which are associated with gingivitis and periodontitis [4]. Malocclusion therapy in adolescents and adults commonly includes fixed orthodontic appliances containing wires, brackets, and ligatures [5]. Materials in these appliances are alloys such as stainless steel (SS), nickel-titanium (NiTi), titanium-molybdenum, and cobalt-chromium [6]. The difficulty in maintaining good oral hygiene is related to the additional retention places of the fixed appliance for plaque accumulation. Some studies suggest that plaque accumulation is especially increased in metal brackets with elastic ligatures in the maxilla, the maxillary amines, and lateral incisors [7], unlike in non-orthodontic patients, where the mandibula and maxillary molars are the primary sites of accumulation [8]. Areas around the brackets (mesial, distal, and gingival) accumulate more plaque than occlusal areas because they interfere most with archwires and ligatures; thus, natural self-cleaning is not possible [9]. Difficult and inadequate oral hygiene by brushing and a lower ability to use dental floss lead to plaque accumulation and oral flora changes [10]. It can cause gingivitis, enamel white spot lesions (WSL), and caries [11]. The progression of gingivitis can lead to periodontitis and ultimately cause irreversible damage, such as the loss of supporting tissue. Studies claim that some orthodontic patients do not complete treatment, because of poor oral hygiene. Orthodontic patients need to have proper oral hygiene because it is very challenging, and patient motivation is crucial [12]. Therefore, patients should be aware of the consequences of improper hygiene. The clinician may use tools other than informed consent to motivate the patient, such as animations, leaflets, and other verbal information [13]. Appliance placement alters the oral microbiota, and we can observe high concentrations of acidogenic bacteria such as _Streptococcus_ and _Lactobacillus_ which result in WSL progression and caries development in patients with fixed appliances within a month after placement [14], unlike caries development in the mouth without braces that can take up to 6 months [15]. Aetiological factors associated with periodontitis include an increase in Gram-positive supragingival bacteria, such as _Streptococcus_ and _Actinomyces_. Regarding gingivitis, aetiologies include an increase in Gram-negative _Fusobacterium_ and _Bacteroides_[16]. In addition to mechanical plaque control, such as brushing and flossing, chemical plaque control can be performed. The gold standard is chlorhexidine digluconate (CHX DG), which has side-effects such as staining and altered taste after long-term use [17; 18]. Short-term usage is recommended for people with difficulty in maintaining oral hygiene, such as those with fixed orthodontic appliances, mental and physical disabilities, intermaximillary fixations, and postsurgical or systematic diseases with oral manifestations [19].