Pulp Revascularization in a primary Necrotic Central Incisor

Case description

An 8-year-old male patient presented to the pédiatrie dental clinic at Miami Children's Hospital, Miami, Fla., USA. The parent reported that the patient suffered dental trauma 7 months prior, fracturing his permanent maxillary right and left central incisors at the mesial-incisal angle. The pulp was not exposed at the time of injury. Six months after the injury, the patient went to a general dentist with a complaint of spontaneous pain and was prescribed amoxicillin every 8 hours for 2 weeks. One month later, the patient developed an acute apical abscess with swelling buccal to the permanent maxillary left central incisor and was again prescribed the same course of antibiotics. The patient had a regular dental home prior to the injury and had no significant medical history. Upon our examination (2 weeks after the second course of antibiotics), 

(Figure 1) Periapical radiograph sequence of revascularization and apexogenesis. 

(a) Permanent maxillary left central incisor prior to pulp regeneration therapy 

showing an open apex (immature root), restored mesial incisai angle, and periapical radiolucency at the apex of the permanent maxillary left central incisor.

(b) Mineral trioxide aggregate placement at the cervical level after the blood clot 

was formed

(c) Three-month follow-up showing the early stages of apexogenesis

and healing of the periapical radiolucency, and (d-e) Continued healing of the 

periapical area and apexogenesis at 6- and 11 -month follow-ups, respectively.

the permanent maxillary left central incisor still presented an acute apical abscess with buccal swelling. Radiographie examination revealed an open apex and periapical radiolucency (Figure la). The following day, the patient received an endodontic consultation, resulting in a decision to attempt pulp regenerative techniques. At the first treatment appointment, the tooth was nonresponsive to vitality testing with Endo Ice (Coltene Whaledent, Mahwah, N.J., USA) and Vitality Scanner (SybronEndo, Orange, Calif, USA). The patient reported to be sensitive to palpation and had no mobility or discomfort upon percussion. His probing depths were within normal limits on the permanent left maxillary central incisor. The permanent left lateral incisor responded within normal limits to the pulp vitality tests. After administration of local anesthesia with 1.8 ml 2% lidocaine and 1:100,000 epinephrine (Novocol, Cambridge, Ontario, Canada) and rubber dam isolation, the pulp chamber  was accessed from the palatal surface and confirmed necrotic. The canal was irrigated with 6% sodium hypochlorite (Clorox, Oakland, Calif, USA) and dried with sterile paper points (Dentsply, Tulsa, Okla., USA). No instrumentation of the canal was performed. A triple antibiotic medicament in a 1:1:1 ratio—comprised of metronidazole (Pleva Pharmaceutical, Zagreb, Croatia), ciprofloxaein (Teva Pharmaeeutieals, Sellersville, Pa., USA), and minoeycline (Global Pharmaceutical, Philadelphia, Pa., USA)— Figure 2.

(Figure 2) .  Periapical radiograph of the permatient maxillary left central incisot at 2 weeks after initial treatment with triple antibiotic paste, with guttapercha tracing the sinus tract

was used to ease manipulation, the thickening agent carboxymethylcellulose (Spectrum, New Brunswick, N.J., USA) was added and mixed into the triple antibiotic paste with a number 24 spatula (Hu-Friedy, Chicago, 111., USA). This mixture was placed into the root canal with a Centrix syringe and standard syringe tips (Centrix Dental, Shelton, Conn., USA), covered with a sterile cotton pellet, and temporarily restored with CavitG (ESPE, Seefeld, Germany). (ESPE, Seefeld, Germany). Fourteen days after treatment was initiated, the patient returned to the clinic having lost the temporary restoration. At this visit, the patient was re-examined and found to now have a draining sinus tract apical to the permanent maxillary left central incisor (Figure 2). After the local anesthetic was administered and isolation achieved with the rubber dam, the canal was again irrigated with 6% sodium hypochlorite, treated with the same TAP, and covered with a sterile cotton pellet. The access was closed and the tooth was temporarily restored with Gavit-G. The patient was asymptomatic at the 21-day follow-up after the second TAP treatment. After local anesthesia and isolation were obtained, the temporary restoration, eotton pellet, and TAP were removed. The eanal was then irrigated with 6% sodium hypoehlorite and dried with sterile paper points. A number 20 sterile K type endodontie file (Dentsply) was introdueed into the apical area to stimulate bleeding into the eanal spaee. The blood was allowed to reaeh the level of the eementoenamel junetion (CEJ), where a blood clot was formed (Figure lb). Mineral trioxide aggregate (MTA, Dentsply) was mixed with 2% lidocaine and 1:100,000 epinephrine and placed over the clot. A thin layer of cavity liner (Lime-Lite, Pulpdent, Watertown, Mass., USA) was placed over the MTA, cured, and etched, and the access opening was restored with TPH Composite (Dentsply Caulk, Milford, Del, USA). Three months after the regeneration procedure, the patient was still asymptomatic and the sinus traet had healed eompletely. Coverage over the aeeess was intaet and radiographie examination revealed the healing of the periapieal area and the appearanee of the apex elosing (Figure le). Six months after the regeneration proeedure, the patient was asymptomatie but the permanent maxillary left eentral ineisor presented with a slight grayish diseoloration (Figure 3). 

(Figure 3). Patient's anterior teeth at -11 month follow-up follow-up showing

a slight grayish discoloration in the permanent maxillary left central incisor.

The tooth had no mobility, no pain on pereussion or palpation, and no positive reaetion to the eold test. The lamina dura and periodontal ligament were within normal limits, and continued root development was noted (Figure Id). Eight months after the regeneration procedure, the tooth was restored with TPH composite. The patient was asymptomatic, and the grayish discoloration was still present. At the following recall exam, 11 months after treatment, root development appeared complete and dentinal wall thickening was noted, particularly in the root's apical third (Figure le).

Discussion

The resulting closure of the root apex and thickening of the root walls demonstrated successful revascularization and maturogenesis after applying triple antibiotic therapy and MTA' seal of a necrotic immature permanent ineisor. Vitality testing would not be viable sinee the eoronal plug does not allow aeeess to the dentinal tubules where new pulp tissue has been regenerated below the CEJ level. Other studies report similar findings on inconclusive pulp vitality tests after regeneration procedures." Discoloration of the newly vascularized incisor correlates with previous studies using tetracyclines in their antibiotic medicament. In out study, white MTA vs gray MTA was used to minimize the possibility of discoloration. Bonding techniques have been attempted to reduce the negative esthetic effect, but no treatment has yet proven effective for improving discoloration.Pediatrie dentists and endodontists alike agree that regenerative techniques will be viable treatment modalities in the future. Half of the endodontists in one study already used some type of regenerative therapy in their practice. Current technology, including laser Doppler flowmetry, allows us to

effectively evaluate whether revascularization has occurred and whether regenerative techniques need to be initiated.Revascularization has even been successfully attempted in primary teeth.'"'With an increasing breadth of clinical evidence and practitioner acceptance, regenerative techniques may become a standard technique in treating immature necrotic permanent teeth.

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