Title	In Mature Necrotic Teeth, Apical Preparation <0.5 mm Results in Favorable Outcomes for Regenerative Endodontic Procedures
Clinical Question	In mature necrotic teeth, does preparing the apex to <0.5 mm result in better outcomes following a regenerative endodontic procedure (REP)?
Clinical Bottom Line	For mature teeth with pulp necrosis, an apical size preparation <0.5 mm results in favorable outcomes for REP. This is supported by randomized controlled trials in which preparation of the apex to <0.5 mm resulted in successfully result in regression of clinical signs and symptoms, healing of periapical lesion, and regaining of the tooth sensibility.
Best Evidence
PubMed ID Author / Year Patient Group Study type (level of evidence) 32173020 El-Kateb/2020 18 mature maxillary anterior necrotic teeth with periapical lesions Randomized Controlled Trial Key results Mature teeth with pulp necrosis and periapical lesions undergoing REP showed healing of the lesion, reduction of clinical signs and symptoms associated with the pathology. They compared the outcomes with two apical preparation sizes: 0.30 mm (test group) and 0.50 mm (control group), both 0.5 mm or smaller, and they did not find any difference in these two groups. Additionally, the study demonstrated regeneration of pulp-like tissue, which was compared to the natural teeth using Signal Intensity (SI) obtained from an MRI scan. The SI of the teeth treated with REPs was similar to that of contralateral healthy teeth. The outcomes were compared in terms of attaining the primary, secondary and tertiary goals of regenerative endodontic procedures. 31155298 Arslan/2019 56 mature necrotic teeth with large periapical radiolucency Randomized Controlled Trial Key results In the study conducted by Arsalan et al (2019), the outcomes of REPs were compared with conventional root canal treatment. The study K-file (0.25mm at tip) was passed beyond the apex to induce bleeding inside the canal. It can be assumed that the file was passed maximum 3-4 mm beyond the apex which can lead to opening of the apex to 0.40mm to 0.45mm, which is still <0.5mm. The results of the study showed that teeth treated with REPs have a similar success rate as that of conventional root canal treatments.
Evidence Search	((necrotic teeth) AND (regenerative endodontic procedures)) AND (endodontics)
Comments on The Evidence	The study by El-Kateeb et al. was a prospective, parallel-design randomized controlled clinical trial. They recruited adult male and/or female patients 20–40 years of age and free from systemic diseases. Eighteen maxillary anterior necrotic mature teeth with single canals with periapical lesions were included in the study. In the test group (n = 9 teeth) the apex was prepared to ProTaper Next (Dentsply Sirona, York, PA) Size X3 (0.30mm) and the control group (n = 9 teeth) ProTaper Next (Dentsply Sirona, York, PA) Size X5 (0.50mm). The allocation ratio between the test and the control groups was 1:1. The participants, the radiographic specialists, and the statistician were blinded to the treatment group. Postoperative clinical follow-up was done for both groups after 1, 3, 6, 9, and 12 months. Postoperative radiographic follow-up included periapical digital radiographs for both groups after 3, 6, 9, and 12 months to assess periapical healing. In addition, MRI SI measurements of the regenerated pulplike tissue after 3, 6, and 12 months of follow-up were performed. The study by Arsalan et al. was another randomized controlled clinical trial and the researcher and patients were blinded to the treatment group. They included 49 patients in the age range of 18–30 years without systematic disease/allergic reactions and with nonvital single-rooted teeth with 1 root canal with mature roots (closed apices) and a periapical lesion. In the test group, regenerative endodontic procedures were performed and in the control group, the patients received a conventional root canal treatment. The operators followed a standardization protocol and were calibrated with the protocol for each experimental procedure. The patients were followed up to 1 year and assessed clinically and radiographically. The follow up rate was 73.4% of the total patients for 12 months. Perspective: The primary therapeutic goal of REPs is resolution of periapical pathosis while promoting the survival and function of the tooth, the secondary therapeutic goal is continued root development in immature teeth, and the tertiary goal is return of pulp vitality. Apical size has been previously shown to be critical for a successful REP outcome. However, majority of studies are limited to apical size in immature teeth. In mature teeth with closed apex, minimum apical preparation continues to be an important factor as it determines the ingress of stem cells within the canal system. The above articles provide evidence that apical size of >0.5 mm is sufficient to obtain clinically successful REP outcomes.
Applicability	REPs provide a unique advantage to conventional root canal treatments by regaining vitality and potentially gaining an immunocompetent pulp potentially lending greater longevity to teeth. These are desirable advantages and applicable to a wider patient population. However, the factors that might limit the applicability of REPs at the provider level is the technique sensitivity and the skills required to accomplish successful outcomes, as well as the use of CBCT for case selection, the surgical operating microscope for adequate disinfection and treatment, and patient reliability for frequent follow ups.
Specialty	(Endodontics) (General Dentistry)
Keywords	necrotic teeth; regenerative endodontic procedures; endodontics
ID#	3458
Date of submission	12/03/2020
E-mail	shirodkar@uthscsa.edu
Author	Gautam Shirodkar, BDS MS
Co-author(s)	Ryan Raouf, DMD
Co-author(s) e-mail	raoufr@uthscsa.edu
Faculty mentor	Dr. Nikita Ruparel, DDS PhD
Faculty mentor e-mail	ruparel@uthscsa.edu
Basic Science Rationale (Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?) None available
Comments and Evidence-Based Updates on the CAT (FOR PRACTICING DENTISTS', FACULTY, RESIDENTS and/or STUDENTS COMMENTS ON PUBLISHED CATs) None available