Endodontic treatment of immature permanent teeth with necrotic pulp consistently challenges clinicians due to the weak root wall and divergent apical foramen. To date, the REPs has been widely used to treat the above cases because they allow further increases in root length and root wall thickness, leading to the closure of apical foramen [6, 16,17,18,19]. Although the literature has demonstrated the efficacy of REPs in apical lesion healing and continued root development, failed REPs and absence of root development after REPs are also reported [11, 12, 20, 21]. A few studies have investigated the prognostic factors affecting the outcomes of REPs to guide clinical work [10, 13, 14]. However, no definite conclusion has been drawn due to the different study designs and the limitation of sample sizes (50, 62, and 46 cases receiving REPs, respectively) in these studies [10, 13, 14]. To understand the possible prognostic factors influencing the outcome of REPs, we designed this retrospective study based on our REPs database with a relatively large sample size of 116 patients from 2013 to 2017. As we know, preoperative factors and treatment protocols may affect the outcomes of REPs. In the present study, we focused on the influence of preoperative factors on the root development of REPs due to the standard operative procedures for the included patients.

The REPs have achieved favorable outcomes with high success rates ranging from 83.3 to 100% for immature teeth with apical periodontitis [7,8,9,10]. However, growing evidences showed that failed REPs could be found with persistent infection, root resorption and fracture [17, 22,23,24]. The systematic analysis by Almutairi et al. found that 79% of failed RET cases were presented with persistent infection, and 22 out of 37 failed cases (56%) were caused by dental trauma, and 39% of failed RET cases were identified after more than 2 years of follow-up [25]. In present study, two cases caused by dental trauma failed because of the infection recurrence within 1 year and over 2 years after REPs, respectively. The possible reason for the failure may be associated with the etiology of dental trauma, which may damage the blood supply in the apical area and decrease the resistance to infection. For the failed REPs, Lee and Song have raised that all endodontic procedures, second REP, apexification, conventional RCT, surgical approaches, and extraction could be considered modalities according to treatability of the tooth, accessibility to the canal, and the presence of an apical seat [24]. Apexification in nonvital permanent immature teeth with corono-radicular adhesive restoration can successfully achieve a favorable long-term outcome and may be a conservative alternative for the failed REPs [26]. In our study, apexification was chosen for the failed case within 1 year due to the absence of an apical seat and extraction for the failed case over 2 years because of the persistent infection and patient’s requirement.

Dens evaginatus, trauma and dental caries are the major causes of immature permanent teeth with necrotic pulp and apical periodontitis. A meta-analysis reported that there was no evidence of a difference in aetiology for the outcomes of REPs, in which success was defined as teeth being asymptomatic and teeth not requiring any other endodontic treatment after REPs (primary goal of AAE) [27]. However, our previous prospective study found that REPs cases with dens evaginatus had significantly better outcomes than those with an aetiology of dental trauma in achieving root development with a simple size of 69 REPs cases [8]. Chrepa et al. also reported that aetiology was a significant predictor of failure as well as root development [10]. In our present study, all the cases were caused by dens evaginatus or trauma, and the results confirmed that dens evaginatus cases showed a better prognosis than trauma cases in terms of root development with a relatively large sample size of 116 REPs cases, which was also verified by multivariate logistic regression. This may be because dental trauma induces damage to the apical papilla and Hertwig epithelial root sheath, which might lead to failure of continued root maturation. Within the limitation of the present study, we may conclude that aetiology would affect root development rather after REPs.

The diagnosis was evaluated as a potential prognostic factor in this study. We used current AAE diagnostic terminology and divided the cases into four clinical categories according to periapical status: asymptomatic apical periodontitis, symptomatic apical periodontitis, chronic apical abscess, and acute apical abscess [28]. The retrospective study by Chrepa et al. stated that apical diagnosis based on AAE criteria was considered a significant predictor for radiographic root area (RRA) change after REPs, indicating that the status of infection/inflammation at the apical area could influence the regulation of root development [10]. In contrast, our results showed that the diagnosis did not significantly affect root development after REPs defined by our study, suggesting that the clinical diagnosis may not be used as case selection for REPs. The opposite outcomes may be due to the different variables and statistical approaches used in the studies. In our opinion, regardless of the diagnosis, microbial control is the foundation for regenerative endodontic treatment, and appropriate disinfection of the canal is needed to achieve apical healing. Once the infection is well controlled, root development would be possible.

It has been reported that younger patients have a better healing ability in terms of dental pulp regeneration [10]. Estefan et al. explored the influence of age (9–18 years old) on the success of REPs and found that compared to the older age group (14–18 years old), the younger age group (9–13 years old) showed a significant increase in length independent of the preoperative size of apical diameter [14]. Chrepa et al. conducted a San Antonio study, in which patient ages ranged from 7 to 26 years, and found age was one of the significant predictors of failure and RRA change with an increase in age being associated with less gain in RRA [10]. However, our results showed no significant difference between ages on root development of REPs. This could be because the age range of patients in present study was between 7 and 13 years old with great healing ability and stem cell regenerative potential. Including samples with a wider age range (> 13 years old) should be considered for future studies to achieve more specific outcomes.

Preoperative root status/root morphology has also been evaluated as a prognostic factor of REPs. The study from Estefan et al. found that teeth with wider diameters (≥ 1 mm) demonstrated greater increases in root thickness, length, and apical narrowing [14]. Fang et al. conducted a literature search and concluded that teeth with apical diameters < 1.0 mm achieved clinical success after REPs, and teeth with apical diameters of 0.5–1.0 mm attained the highest clinical success rate [15]. In our study, the initial apical foramen size in the trauma group impacted the root development of REPs. The larger apical foramen achieved more Type I outcomes after REPs, which may be due to the abundant blood supply provided via the large apex.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.


This article is autogenerated using RSS feeds and has not been created or edited by OA JF.

Click here for Source link (https://www.biomedcentral.com/)