In both cases, the medical history was reviewed and considered non-contributory. An intra-oral examination was conducted to assess periodontal pocket depth and mobility, which were considered within physiological limits prior to the radiographic investigation. A pulpal and periapical diagnosis was made for both cases, combining the examination findings, pulpal tests (in case 1), and periapical radiographs. Endodontic therapy was recommended as a treatment plan to both patients, who accepted the plan and signed informed consent forms. The treatments were performed after local anesthesia with 1.8 mL of 4% articaine with 1:200.000 epinephrine (Artinibsa, Inibsa, Spain), and rubber dam placement. Prior to mechanical instrumentation of the canals, a manual glide path was established with an ISO size 10 K-file (K-File; Dentsply, Ballaigues, Switzerland). Full debridement was performed under copious irrigation with 5.25% sodium hypochlorite (Denta Flux; J. Ripoll SL, Murcia, Spain) using a 5 mL syringe and a 27G notched needle (CanalPro Slotted-End Tips, Coltene, Lezzenes, France). The working length was established using an electronic apex locator (miniRoot Zx; Morita, Irvine, CA, USA), with additional confirmation via periapical radiography. Mechanical instrumentation was performed using a VDW Silver motor (VDW, Munich, Germany). The final irrigation protocol also included 1 minute of irrigation with 10% citric acid prior to a final sodium hypochlorite rinse under sonic agitation with EndoActivator (Dentsply Maillefer, Ballaigues, Switzerland), after which the canals were dried with 4% tapered paper points (Zipperer; VDW) and obturated with gutta-percha and sealer (AH Plus Jet; Dentsply DeTrey, Konstanz, Germany) using the continuous-wave condensation technique performed with the B&L system (Biotech, Seoul, Korea). After canal obturation, the pulp chambers were rinsed with alcohol, the canal orifices were sealed with Ionoseal (VOCO GmbH, Cuxhaven, Germany), and the access cavities were temporarily filled with Cavit (Cavit W; 3M ESPE, Seefeld, Germany). The patients were referred for a restorative appointment for definitive restoration of the endodontic accesses.

A 43-year-old female patient was referred to an endodontic appointment at a private practice after an incidental radiographic finding of a periapical radiolucency associated with the maxillary left lateral incisor (tooth #22), which presented with a sound crown (no caries or restorations) (Figure 1A). The patient reported a history of dental trauma with an impact to the upper anterior teeth about 20 years earlier. There was pain to buccal palpation over tooth #22, and vertical percussion also elicited a painful response. There was no response to cold (Endo cold spray; Henry Schein, Hessen, Germany), with normal responses on both adjacent teeth. A diagnosis of necrotic pulp, probably of traumatic origin, and symptomatic apical periodontitis was established. The endodontic access was prepared using a round diamond bur (Komet Medical, Lemgo, Germany) and refined using an Endo Z bur (Dentsply Maillefer). After determining the working length (Figure 1B), the Reciproc (R25 and R40; VDW) system was chosen for instrumentation. Due to time limitations, the root canal treatment was not concluded at the first appointment. A dressing of calcium hydroxide (UltraCal; Ultradent, South Jordan, UT, USA) was applied as an intracanal medication between appointments. At the second visit 2 weeks later, the tooth was asymptomatic, and the root canal treatment was completed (Figure 1C). At 3 months post-treatment, the patient developed an acute apical abscess. An additional periodontal examination was done, and cone-beam computed tomography (CBCT) was performed to fully ascertain the dimensions and extension of the periapical lesion (Figure 1D-1F) in order to establish a proper treatment plan. EMS was then recommended and accepted, and the patient signed a written consent form. After the EMS procedure (Figure 1G-1K), with the details of the general procedures explained below, a follow-up radiographic examination was performed at 6 months (Figure 1L), showing good progression of osseous healing. At 12 months (Figure 1M) there was complete resolution of the periapical lesion.

A 32-year-old female patient was sent for an appointment at the endodontics post-graduate clinic at the University of Lisbon, with a previously initiated root canal treatment on the maxillary left lateral incisor (tooth #22). The referring clinician reported an inability to dry the canal after several rounds of intracanal medication. The tooth presented with mesial and distal composite restorations and a provisional filling over the palatal access. There was pain on palpation and percussion, while the periodontal probing was normal. A CBCT scan was requested, and it revealed an extensive lesion involving both buccal and palatal cortical plates. Considering the clinical and imaging data (Figure 2A-2E), root canal retreatment was advised. The treatment was performed under magnification through a dental operating microscope (M320; Leica, Wetzlar, Germany). After removing the provisional filling, the endodontic access was refined with Start-X 3 ultrasonic tip (Dentsply Maillefer USA, Los Angeles, CA, USA). The intracanal dressing was rinsed with copious irrigation (Figure 2F) and the working length was determined (Figure 2G). The WaveOne Gold system (Primary, Medium and Large; Dentsply Maillefer) was chosen for instrumentation and the treatment was completed in a single session (Figure 2H). Two months after the appointment, the patient reported spontaneous, continuous dull pain over the periapical area of the treated tooth. After clinical observation, EMS was advised, and the patient signed a consent form. The microsurgical procedures (Figure 2I-2L) are described below. Radiographic examinations at 2, 4 and 6 months (Figure 2M-2O) showed a gradual increase in bone trabeculation. At a 1-year follow-up (Figure 2P) there was considerable ossification of the periapical area with an apparent residual scar tissue area.

The L-PRF was obtained using the IntraSpin system (BioHorizons, Birmingham, AL, USA). The patient’s blood was drawn by a nurse practitioner on-site immediately before surgery into 9 mL plastic tubes without anticoagulant agents. The collected blood samples were immediately centrifuged for 15 minutes at 2,700 rpm. The produced clots were extracted from the container using thin sterile forceps and placed in a specially designed kit to compress L-PRF clots into L-PRF membranes with a consistent thickness of 1 mm.

The surgical procedures were done under magnification through a dental operating microscope (M320; Leica) at the university clinic. Local anesthesia was achieved with buccal and palatal infiltrations of 4% articaine with 1:100,000 epinephrine. A full-thickness mucoperiosteal flap was raised with a microblade scalpel (SybronEndo, Orange, CA, USA) through a papilla-based incision extending from the mesial aspect of tooth 21 to the distal aspect of tooth 23 and supported by 2 vertical releasing incisions (Figures 1G and 2I). The cortical buccal plates over the intended osteotomy sites were very thin, and access to the apices of both teeth was gained with the aid of a surgical curette (Hu-Friedy, Chicago, IL, USA). High-speed osteotomy tungsten carbide round burs (Dentsply Sirona, Philadelphia, PA, USA) were used under irrigation to refine the bony margins. All granulomatous tissues were removed by manual curettage and hemostasis was obtained with the aid of Telfa pads (Covidien, Cascais, Portugal). Apical root resection (3 mm) was performed with a Zekrya (Dentsply Sirona) surgical bur, and the retrograde preparation was accomplished with JT-2B ultrasonic tip (Biotech). After drying the root-end preparation with paper points, an apical plug of MTA (ProRoot MTA; Dentsply Tulsa Dental, Tulsa, OK, USA) was placed (Figures 1H and 2J). L-PRF was used to fill the bone defect in both cases and also cover the cortical bone as a membrane (Figures 1I and 2K). The flap was repositioned with the aid of non-resorbable sutures with 5.0 silk (Braun, Tuttlingen, Germany) (Figure 1J and 2K) and 0.2% chlorhexidine gel (Elugel; Pierre Fabre Oral Care, Castres, France) was applied with a sterile cotton gauze pad over the area that received the intervention. The patients were medicated with systemic antibiotics (875 mg of amoxicillin + 125 mg of clavulanic acid, 1 pill every 12 hours for 8 days), a non-steroidal anti-inflammatory drug (600 mg of ibuprofen, 1 pill every 8–12 hours for 3 to 5 days) and pain medication (300 mg of clonixin, up to 2 pills a day to manage symptoms) along with dedicated post-surgical instructions. Sutures were removed 5 days after the procedure, with good tissue healing and no major discomfort.