# Antimicrobial and Antibiofilm Properties of Bioceramic Materials in Endodontics
## 3 Bioceramic Root Repair Material  
### Mta  
Mineral trioxide aggregate (MTA) (Dentsply-Tulsa Dental, Johnson City, TN, USA) is one of the most commonly used biomaterials in endodontics based on its excellent biological, chemical, and physiological properties (Figure 3a). Mineral trioxide aggregate contains a mixture of dicalcium silicate, tricalcium silicate, tricalcium aluminate, gypsum, tetracalcium aluminoiferrite, and bismuth oxide [11]. MTA has been widely used for vital pulp therapy, apical barrier formation, repair of root perforations, and root-end filling. The antibiofilm properties of MTA have been extensively evaluated using different strains of microbes/biofilms that present in the oral cavity and using different microbiological testing methods [11].  
Figure 1: Scanning electron microscope image of multi-species mature plaque biofilm grown on collagen-coated hydroxyapatite disk.  
Figure 2: FIB-SEM image of a milled mature plaque biofilm composed of bacterial cells (white arrows), extracellular polymeric substances (yellow arrows) and micro water channels (green arrows).  
The reason why a tricalcium silicate-based cement, such as MTA, has antib biofilm activity is mostly due to the pH increase during the setting process. The pH can increase from the formation of calcium hydroxide during the hydration reaction of MTA. [PERSON] et al. [26] showed that the pH of MTA is 10.5 at the time of mixing and can increase up to 12.9 after 3 h of setting. High pH affects the structure of the endodontic bacterial cells by causing DNA degradation and cellular protein damage, resulting in the decrease of cellular viability [27; 28].  
_Enterococcus faecalis_ biofilm has been claimed to be unable to survive if the pH values were set to higher than 11.5 [29]. MTA also exhibited antimicrobial activity on other types of bacterial biofilms, including _Staphylococcus aureus_, _Escherichia coli_, _Pseudomonas aeruginosa_, and _Porphyomonas gingivelis_[30]. As well, a recent study showed ProRoot MTA (Dentsply-Tulsa Dental, Johnson City, TX, USA) had antimicrobial activity against _Candida albicans_[31]. Similar antifungal effects were reported in previous studies [32; 33]. Dissimilar results from different studies on the antibofilm activities of MTA may be attributed to the composition of the biofilms and the amount of material applied [11].  
Recently, a \"tooth-on-a-chip\" model was developed to enable direct visualization and analyses of bioceramic cement interactions with oral biofilms [34]. ProRoot MTA was applied using _S. mutans_ biofilm to simulate microbial infection at the biomaterial-dentin interface. ProRoot MTA disrupted the integrity of the biofilm and over 90% of bacterial cells within the biofilms were killed both at the biofilm's outer and inner layers [35]. The antib Biofilm effect was likely due to the high pH microenvironment and calcium ions released from ProRoot MTA [35].  
In clinical reality, MTA commonly interacts with an environment of blood, tissue fluid, and dentin structure. A recent study showed ProRoot MTA killed more bacteria when it was in contact with water than when it was in contact with heparinized human blood [36]. Moreover, the antib Biofilm activity of MTA was significantly reduced after aging for 7 days in water and blood using a direct contact test and an intra-tubular infection test [36].