# Regenerative Endodontics as the Future Treatment of Immutative Permanent Teeth
## 3 Results  
### Root Canal Disinfection  
One of the main conditions for successful REP is disinfection of the root canal [25]. Leaving microorganisms on the canal walls or in the dentimal tubules prevents the development of new tissue and creates a risk of periapical tissue inflammation [26]. The fundamental way to remove necrotic mass and microorganisms from the canal is to irrigate it with disinfectants [27]. In addition, other methods of disinfection are proposed. Mechanical instrumentation is generally contraindicated to prevent the further weakening of thin canal walls [28]; however, according to some authors, careful preparation of the canal with hand instruments may be necessary to remove bacterial biofilm altogether [29]. During rinsing, gentle manipulation with an endodontic needle (with side holes and a blunt tip) is recommended; it should be loosely placed in the canal lumen, approximately 1-2 mm from the root apex. Careful irrigation with plenty of fluids is required. The primary agent is sodium hypochlorite (NaOCI) of which the concentration used by various authors  
Figure 1: Flowchart presenting database search strategy. varies between 1% and 6% [30]. According to some researchers, high concentrations are not advisable, due to the potential risk of damaging stem cells in the periapical region [11; 31]. It was shown that an increase in the concentration of sodium hypochlorite improves the bactericidal effect but at the same time hinders cell proliferation [32; 33; 34]. According to the American Association of Endodontists, NaOCl at a 1.5-3% concentration is a reasonable compromise between the antibacterial efficacy of the preparation and stem-cell protection [35]. Heating 2.5% NaOCl to 37 \({}^{\circ}\)C results in its disinfecting potential reaching the same level as the 5.25% solution [36]. Alternatively, 0.12% or 2% chlorexidine (CHX) is used [9], but there is a risk of stem-cell damage, even in this case. Therefore, [PERSON] et al. [37] suggested shortening the irrigation time. After the application of disinfectants, it is suggested to use a 0.9% saline solution (NaCl) to remove the remains of previously used agents, or 17% ethylenediaminetetraacetic acid (EDTA) [38]. The use of EDTA is justified because of its ability to remove the smear layer, resulting in better penetration of the topically applied therapeutic agents. In addition, the chelating effect after EDTA application promotes the release of growth factors from dentinal tubules, migration and differentiation of stem cells, and adhesion of newly forming tissue to the root canal walls [11; 29; 39]. In addition to rinsing fluids for disinfection, the use of intracanal medications is recommended between visits, for instance, standard triple antibiotic paste (TAP) or calcium hydroxide. TAP consists of minocycline, ciprofloxacin, and metronidazoleze in a 1:1:1 ratio and an appropriate carrier (propylene glycol, macrogl, saline solution). The choice of antibiotics is dictated by the spectrum and mechanism of action. It was proven that such a combination of drugs guarantees effective antibacterial activity against microorganisms present in the root canal [40; 41]. However, several disadvantages were also reported when TAP was used, such as cytotoxicity against stem cells, risk of tooth discoloration, development of drug resistance, and difficult removal from the canal [42; 43]. The American Association of Endodontists (AAE) recommends a paste concentration of no more than 1-5 mg/mL, arguing that this would minimize any possible toxic effect on stem cells [35]. A different view is presented by the European Society of Endodontology (ESE) [44; 45]. Considering the reported disadvantages of TAP, ESE suggests the use of calcium hydroxide, whose antibacterial efficacy is comparable to TAP, while its toxicity to stem cells is significantly lower [46]. Consensus is yet to be reached among researchers on disinfectants used in REP, and conflicting views can be found in the literature. [PERSON] et al.