Study aimed at assessing the clinical and radiographic success of pulp regeneration using injectable platelet-rich fibrin in mature permanent molars with apical periodontitis versus root canal treatment using Gutta Percha (GP) obturation.

Randomized pilot study, parallel groups design with 1:1 allocation ratio.

PICOT:

Population: Mature first permanent molar with apical periodontitis. Intervention: Regeneration using injectable platelet-rich fibrin. Control: Root canal treatment using GP obturation. outcomes: clinical and radiographic success. Source of patients: this study will be conducted in the outpatient postgraduate clinic of the Pediatric Dentistry and Dental Public Health Department - Faculty of Dentistry, Cairo University, Egypt.

Written Informed consent from participating children/parents. Baseline records photographs, clinical inspection, percussion test, periapical radiograph, and personal data collection will be conducted.

A diagnostic chart with personal, medical, and dental history will be filled Diagnosis and treatment of the cases will be performed according to the Treatment Standards of the American Association of Endodontists (AAE) 2020 of Non-Surgical Endodontics for the Uncomplicated Mature Permanent Teeth.

Allocation (concealed by withdrawing a sealed opaque envelope containing Four-folded numbered papers containing the type of treatment then writing the patient's name and I.D. on it and will be opened in the next visit).

The radiographic examination will be performed by taking a periapical X-ray using (a parallel technique) to assess the inclusion criteria. The preoperative radiograph will serve as a reference for the follow-up radiographs. Standardization of the technique to avoid any vertical dimension distortion and provide reproducible images using an X-ray holding device.

An individual XCP (Extension Cone Paralleling) index will be prepared for each patient by registering the bite to allow consistent comparisons of the radiographs.

Intra-operative procedure:

First appointment:

• Local anesthesia administration using 1.8-mL of articaine 4% with epinephrine 1:100000 using inferior alveolar nerve block.
• Rubber dam will be applied, then caries removal and access cavity preparation will be established using a sterile carbide bur no. 8, and Endo Z bur.
• Initial canal exploration will be performed with Endo Probe and no. 10 K-file to gauge canal size, shape, and configuration. Working length will be determined using an apex locator with no 15-hand K-file that will be kept 0.3 mm short of the radiographic apex and will be confirmed radiographically.
• Then, the root canal preparation will be done as follows:

Rotary instrumentation will be preceded by manual hand instrumentation using no 20 K-file to check the patency. Then, the rotary instrumentation will be done using rotary files.

EDTA gel will be used as a lubricating paste during canal preparation with rotary files.

Sodium hypochlorite (1.5%) and saline irrigation using a side vented needle into the apical third of the canal to remove debris with copious irrigation using ultrasonic irrigation.

Dryness will be done using paper points size 30. The root canal will be filled homogeneously to the working length with Calcium Hydroxide paste (Metapaste), then, a small Teflon will be applied above the orifices and the tooth will be temporarily restored with Glass Ionomer restorative material till the next appointment.

Second appointment:

All the patients will be recalled after 3 weeks, if the symptoms are suggestive of persistent infection, the root canals will be re-irrigated with sodium hypochlorite followed by saline, and reinjected with calcium hydroxide paste. If the symptoms are relieved, patients will proceed to the next step.

• A 1.8-mL of articaine 4% with epinephrine 1:100000 will be administered as inferior alveolar nerve block. The rubber dam will be placed, and the glass ionomer cement and Teflon will be removed. The root canals will be agitated with master apical K-file and re-irrigated using 17% EDTA solution followed by saline irrigation, then the canals will be dried using a paper point.
• For the intervention group, I-PRF Regeneration will be applied.
• For the control group, root canal treatment will be applied.

C) Follow up:

Clinical evaluation will be performed on 1, 3, 6, 9, and 12 months post-operatively.

Radiographic evaluation will be performed pre-operatively (baseline), and postoperative following the second appointment at 6, and 12 months using the individualized XCP (Extension Cone Paralleling) index and the Digital X-ray machine.

Inclusion Criteria:

1. Children aged between 10-15 years.
2. First Permanent molar diagnosed with apical periodontitis.
3. A cooperative and compliant patient/ parent.
4. Patients not allergic to medicaments necessary to complete the procedure.
5. Patients with no history of chronic systemic diseases.

Exclusion Criteria:

1. Teeth indicated for post and core.
2. Non-restorable tooth.
3. Previous root canal treatment.
4. Curved canal of more than 25°.
5. Periodontal pocket larger than 3 mm.
6. Teeth with developmental anomalies.