# Evaluation of Biodentine Tricalcium Silicate-Based Cement after Chlorhexidine Irrigation
## 1 Introduction  
According to the European Society of Endodontology, calcium silicate-based cements are currently the most recommended group of bioactive materials for specialistic endodontic regenerative treatment, such as for the management of deep caries and the exposed pulp [1]. The main advantage of these materials is their ability to stimulate the amelobal activity to create a mineralized barrier between the cavity and the pulp [2]. Their curative properties, biocompatibility, and antimicrobial activity facilitate biological therapy of pulpal and periodontal tissues [3, 4]. Research has also shown a lack of toxic, mutagenic, or carcinogenic effects on the pulp and periapical tissues [5]. Calcium silicate-based cements are hydraulic. This means, that they can be applied in a humid environment without a significant risk of losing their properties, as they set in a process of hydration [6]. The key product of the setting reaction is calcium hydroxide, which is responsible for, among others, the antibacterial activity of biocements [7]. In 2009, Septodont (Saint-Maur-des-Fosses, France) presented a promising product named Biodentine, defining it as a bioactive dentin substitute [8]. It is a synthetic tricalciumsilicate-based cement of high biocompatibility [7; 9]. It has been proven that in contact with the exposed pulp, Biodentine creates optimal conditions for maintaining its vitality. It releases calcium ions much faster than other cements from this group, inducing the formation of a dentin bridge [10]. Thanks to its properties, Biodentine is a material with a wide range of applications. These include: the replacement of the lost dentin structure with immediate or nonimmediate composite enamel reconstruction [11], pulp coverage--direct or indirect [12], pulpotomy of primary or permanent teeth in cases of reversible and irreversible pulp inflammation [13], treatment of teeth with incomplete apical development or open apex--apexogenesis and apexification [14; 15], repair of perforations or perforating internal resorptions [16], and root canal filling during conventional endodontic treatment or retrograde filling during endodontic microsurgery procedures [17]. Root or chamber wall perforation was a clinical scenario taken into account by the authors when designing this research study. It is a communication between the internal root canal system and the external surface of the tooth caused by pathological (resorption, caries) or iatrogenic mechanisms [18; 19; 20]. This nonphysiological connection can lead to the transfer of bacterial infection from the tooth cavity towards the periodontium and vice versa, which, in the absence of appropriate treatment, may result in tooth extraction. Therapeutic success depends largely on early diagnosis and immediate implementation of appropriate treatment [21]. Therefore, any perforation should be treated as soon as discovered to prevent further complications. This may pose a technical problem in the chemo-mechanical preparation of the root canal system, where the cleaning and shaping has to be performed after closing the perforation. When the perforation is closed prior to completing the root canal preparation procedures, the material has to withstand the forces and factors arising from the continuation of treatment [22]. In this paper, the authors researched the influence of irrigation with 2% chlorheximide digluconate on the Biodentine dicalcium silicate-based cement surface. Chlorhexidine (CHX) is a strong base, currently used in endodontics as an irrigant in the form of 2% chlorheximide digluconate solution. It is bacteriostatic and bactericidal, with a strong effect on Gram-positive bacteria and a slightly weaker effect on Gram-negative bacteria [23]. This effect is prolonged due to the ability to bind to the hydroxyapatite of enamel and dentin [24]. It also has some fungicidal and virucidal properties.