# Regenerative Endodontics as the Future Treatment of Immutative Permanent Teeth
## 2 Materials and Methods  
Permanent teeth with uncompleted root development and non-vital pulp are the main indications for REP. Teeth with inflammatory lesions of the periapical tissues may also qualify for it. It was demonstrated that the stage of root development and the width of the apical opening, and the age and general health status of the patient influence therapy outcome [1]. Due to the wide, apical opening, the thin root walls, and the high risk of failure of the apexification procedure, REP treatment is indicated primarily for teeth in stages 1 (<1/2 developed root), 2 (1/2 developed root), or 3 (>1/2 developed root) of root development, according to [PERSON] [20]. In an almost-developed root with an open apex (stage 4), apexification treatment or REP should be considered. Studies show that REP is possible if the diameter of the apical foramen is <1 mm [21; 22]. The prevailing view in the literature is that the minimum apical width at which REP can be performed is 0.5-1 mm [23].  
Since the expected treatment outcome is living tissue in the canal, restoration with root-crown posts is excluded. Therefore, REP should not be performed in cases of significant destruction of the hard tissues of the tooth [23].  
The highest probability of therapeutic success occurs in young patients between nine and 18 years of age; the younger the patient, the higher the chances of successful therapy [22; 23]. It is also vital to establish good cooperation with the patient and the caregivers so that they are adequately motivated to follow hygiene recommendations and attend the follow-up appointments [1].  
The relationship between the etiology of pulp necrosis (caries, trauma, malformation) and treatment outcome is yet to be conclusively proven [24].  
Many protocols for regenerative treatment can be found in the literature. In all of them, the following steps can be distinguished: disinfection of the canal, delivery of REP components, closure of the canal and cavity, and follow-up visits.  
This paper focuses on comparing the REP protocols available in the literature. The selected publications contain a thorough description of different approaches to the root canal disinfection procedure, scaffold type, final tooth restoration material, follow-up appointment frequency, and treatment results. Figure 1 presents a flowchart, which demonstrates the database search strategy used in this paper. We started scoping the available literature in PubMed.gov, using the keywords 'pulp revascularization' or'regenerative endodontics'. Another filter used was the year of publication--we selected papers written after 2007; then, the search was narrowed to the literature published in English, describing human species and with text availability: free full text or full text. Subsequently, we selected the papers in which the authors accurately describe the disinfection protocol, scaffold and restorative material as well as follow-up visit schemes. However, all of the selected papers describe successful cases. Unfortunately, very few reports on REP failures are available in the literature; thus, the correct choice of the REP protocol and the profound interpretation of its results are significantly hindered. Therefore, the authors of this paper also propose an original REP protocol based on the available literature.