Regenerative Endodontic Therapy of an Immature Permanent Molar With Necrotic Pulp and Symptomatic Apical Periodontitis Using Platelet-Rich Fibrin: A 52-Month Follow-Up Case Report.

Background: Regenerative endodontic therapy (RET) is a biologically based, conservative treatment approach for immature permanent teeth with necrotic pulp that aims to induce physiologic root closure and thickening of root dentin. This case report describes the 52-months clinical and radiographic outcome of RET using platelet-rich fibrin (PRF) as a scaffold in an immature permanent molar with necrotic pulp and apical periodontitis. Case Report: A healthy 7-year-old boy presented with pain and a decayed tooth in the lower left back region of the jaw of 3-4 months' duration. Swelling in the same region 15 days earlier had resolved spontaneously. Clinical examination revealed a deep carious lesion in tooth 36. Oral hygiene was poor, and the tooth failed to respond to cold and electric pulp testing (EPT), with mild tenderness to percussion and palpation. Radiographic examination showed open apices, thin dentinal walls, and a periapical radiolucency associated with the mesial root. After informed consent, local anesthesia was administered, and under rubber dam isolation, caries was removed and an access was cavity prepared. The canals were located, irrigated with sodium hypochlorite, and dressed with triple antibiotic paste for 4 weeks. At the second visit, intracanal bleeding could not be induced from the periapical region despite repeated attempts; therefore, approximately 5 mL of venous blood was collected from the left antecubital vein to prepare PRF, which was placed into the canals to approximately 1 mm beyond the apices using a hand plugger, with the coronal extent to the level of the cementoenamel junction. A 3-mm layer of white mineral trioxide aggregate (MTA) was placed over the PRF, and the tooth was restored the following day with glass ionomer cement and composite resin. Clinical and radiographic follow-ups were conducted at 9, 18, 24, 36, and 52 months. Progressive healing was observed, including resolution of the periapical lesion, increased root length, thickening of the root dentin, and continued apical closure. The tooth responded positively to cold testing at 18 months and to EPT at 24 months. Conclusion: In this case, RET using PRF as a scaffold was associated with favorable long-term clinical and radiographic outcomes, including resolution of periapical pathology, progressive apical closure, and thickening of the root dentinal walls, in an immature permanent molar with necrotic pulp and apical periodontitis. These findings suggest PRF may be a useful scaffold option for RET in immature molars; however, as a single case, this report cannot establish the efficacy or superiority of PRF over conventional blood clot or platelet-rich plasma (PRP) scaffolds, and prospective controlled studies are needed.