One-step apexification in immature tooth using grey mineral trioxide aggregate as an apical barrier and autologus platelet rich fibrin membrane as an internal matrix.

Immature teeth with necrotic pulp and periapical lesion are difficult to treat via conventional endodontic therapy. Numerous procedures and materials have been utilized to induce root-end barrier formation. Traditionally, calcium hydroxide has been the material of choice for the apexification of immature permanent teeth; however, Mineral Trioxide Aggregate holds significant promise as an alternative to multiple treatments with calcium hydroxide. One of the technical problems associated with the placement of the restorative materials used as artificial barrier is to prevent overfill and underfill. Using a matrix avoids the extrusion of the material into the periodontal tissues. This case report presents the successful healing and apexification with combined use of Mineral Trioxide Aggregate as an apical barrier, and autologus platelet rich fibrin membrane as an internal matrix.

INTRODUCTION

Endodontic management of non-vital young permanent tooth with a wide-open blunder-buss apex has long presented a challenge. In the past, techniques for management of the open apex in non-vital teeth were confined to custom fitting the filling material, paste fills and apical surgery.[1] However, the limited success enjoyed by these procedures resulted in significant interest in the phenomenon of continued apical development, or establishment of an apical barrier referred to as “Apexification”.[2] Several procedures utilizing different materials have been recommended to induce root end barrier formation. Apexification with calcium hydroxide [Ca(OH)2] is the most commonly advocated therapy for immature teeth with non-vital pulp. Whilst the advantages of calcium hydroxide lie in the fact that it has been widely studied and has shown success,[3-5] the disadvantages are its prolonged treatment time, the need for multiple visits and radiographs.[6] In some cases, root resorption possibly caused by trauma, and increased risk of root fracture due to dressing the root canal for an extended time with calcium hydroxide has been reported in teeth undergoing apexification.[7] One alternative to calcium hydroxide apexification is a single-step technique using an artificial apical barrier. The one-step apexification has been described as the non-surgical compaction of a biocompatible material into the apical end of the root canal, thus, creating an artificial apical stop and enabling immediate filling of the root canal.[8] Advantages of this technique include shorter treatment time, and development of a good apical seal.

A number of materials have been proposed for this purpose including tricalcium phosphate,[9] calcium hydroxide,[10] freeze dried bone,[11] freeze-dried dentin,[12] collagen calcium phosphate,[13] proplast (a polytetrafluor-ethylene and carbon felt-like porous material).[14] Antibacterial pastes like metronidazole, ciprofloxacin, and cefactor have effectively encouraged apexification.[15] Deliberate over-instrumentation of the periapical area to produce a blood clot that will induce apical closure has also been described.[16] Over the last decade, mineral trioxide aggregate (MTA) has been researched extensively and reported as a possible answer to many clinical endodontic challenges. Various studies involving MTA in apexification procedures have shown promising results. One of the technical problems associated with the placement of the restorative material used as artificial barrier is to prevent an overfill and underfill. Lemon (1992) introduced the “internal matrix concept” for treatment of root perforations. He recommended the use of amalgam for sealing the perforation, which would be condensed against an external matrix of hydroxyapatite, carefully pushed through the perforation thus serving as an external barrier and matrix.[17] The modified internal matrix concept introduced by Bargohlz uses in contrast to other treatment concepts, collagen as a completely resorbable barrier material and MTA for sealing of the perforation.[18] Repair of perforations requires a matrix to control the repair material. The same concept holds true for placement of the apical barrier in immature tooth.

Platelet Rich Fibrin (PRF) was first described by Choukran et al. in France. PRF belongs to a new generation of platelet concentrates, which has been shown to have several advantages like ease of preparation, lack of biochemical handling of blood which makes this preparation strictly autologus, promotion of wound healing, bone growth, bone maturation, and hemostasis.[19] PRF can be obtained in the form of a membrane by squeezing out the fluids in the fibrin clot. This case report presents the management of an immature tooth (with an open apex) with a single step apical barrier placement using MTA and autologus PRF membrane as an internal matrix.

CASE REPORT

A 20 year-old female patient presented to the department of Conservative dentistry and Endodontics, with pain in the right mandibular posterior region. Patient had experienced continuous dull pain for 3 weeks. Previous dental history included endodontic root canal therapy of #46. No history of swelling was given by the patient. On clinical examination, the right mandibular 2nd premolar was rotated from buccolingual to mesiodistal direction, with the buccal and lingual cusps placed distally and mesially respectively. The tooth showed no signs of caries or fracture [Figure 1a]. Examination of the head and neck region revealed no palpable lymph nodes. Medical history was non-contributory. All vital signs were found to be within normal limits. Oral examination revealed no soft tissue or bony abnormalities. The tooth was not sensitive to palpation or percussion, and was not mobile as well. Radiographic examination (Intraoral periapical radiograph) revealed an incompletely formed apex of mandibular right 2nd premolar that tested non-vital in response to thermal and electric pulp vitality testing, and with a diffuse radiolucency of about 0.5 × 0.5 cm around the apex [Figure 1b]. Occlusal trauma was considered as the possible etiology for the resulting periapical lesion of the tooth #45. Obturation with tooth #46 was not acceptable upon radiographic appearance (obturation was short and IOPA showed some amount of periapical rarefaction). Retreatment with tooth #46 was advised; however, the patient did not give consent for the same.

Figure 1

(a) Pre-operative photograph of the patient in the case study, (b) Pre-operative radiograph of the patient in the case study revealing an incompletely formed apex of mandibular right 2nd premolar, and with a diffuse radiolucency of about 0.5 × 0.5 cm around the apex. Obturation of #46 is also noted here, and not is not meeting acceptable standards, (c) Mineral Trioxide Aggregate apical plug placed in the root canal such that an apical stop approximately 3-4 mm thick is created, (d) Platelet Rich Fibrin Membrane obtained from the patient in the study, (e): Two month follow-up radiograph the patient in the study showing satisfactory healing, (f): One year follow-up radiograph the patient in the study showing satisfactory healing

MANAGEMENT

Local anaesthesia was administered and a rubber dam was applied. Endodontic access cavity was done on the occlusal surface using a No. 2 round bur and EX 24 bur (non end cutting tapered fissure; Mani, Tochigi, Japan). The canal was instrumented lightly with K files (Mani, Japan) with the aim of cleaning the root canal walls of debris. The canal was thoroughly debrided with a copious irrigation of sodium hypochlorite (1%) and saline (0.9%), coupled with ultrasonic agitation (Irrisafe, Satellec, France) to ensure complete removal of the necrotic pulp tissue. The canal was dried with sterile paper points, and Calcium hydroxide (Ultracal XS, Ultradent, South Jordan, and UT) was placed as an intracanal medicament and the access cavity was temporized with Cavit G (3M ESPE; Germany). The patient was recalled after 1 week.

After 1 week, the tooth was asymptomatic. At this appointment, it was decided to use PRF membrane as an internal matrix against which MTA would be placed as an apical barrier. Informed consent of the patient was obtained in writing after thoroughly explaining the clinical procedures, risks involved and clarifying all questions raised by the patient. The root canal was flushed with 1% sodium hypochlorite followed by normal saline. The canal was dried with absorbent paper points (DENTSPLY, Tulsa Dental).

PRF membrane preparation was performed by using the procedure described by Dohan D M et al. 30 minutes before the clinical procedure. 8.5 ml of whole blood was drawn by venipuncture of the antecubital vein. Blood was collected in a 10 ml sterile glass tube without anticoagulant and immediately centrifuged at 3000 revolutions per minute (rpm) for 10 minutes. The resultant product consisted of three layers: topmost layer consisting of acellular platelet poor plasma, PRF clot in the middle and Red Blood Cell's at the bottom. The PRF clot was retrieved and fluids were squeezed out to obtain a PRF membrane [Figure 1d]. PRF membrane was gently compacted using hand pluggers to produce a barrier at the level of the apex with the use of operating microscope (Carl Zeiss). MTA was introduced into the canal and compacted using schilders pluggers (DENTSPLY Caulk, Milford, DE) against the PRF membrane. A radiograph was exposed to confirm adequate placement of MTA to form an apical stop approximately 3-4 mm thick [Figure 1c]. The blunt end of a large paper point was moistened with water and left in the canal to promote setting. A cotton pellet was placed in the chamber and the access cavity was sealed with temporary filling material Intermediate Restorative Material (IRM) (Caulk/DENTSPLY, Milford, DE).

After 1 week, the patient remained asymptomatic and the tooth was isolated and accessed as before. A hand plugger was lightly tapped against the MTA plug to confirm a hardened set. The canal was obturated using AH Plus sealer (Dentsply DeTrey, Konztanz, Germany) and injectable thermoplasticized gutta percha (E and Q plus Meta Biomed Co ltd-Korea). The tooth was restored with resin composite. Teeth # 45 and 46 were both rehabilitated with crowns after 2 months post-operatively. The patient was recalled 2 months postoperatively, and after 1 year. Follow-up radiographs at 2 month interval showed reduction in sizeof radiolucency and at 1 year interval showed further healing with calcifc barrier at the apex. [Figure 1e and 1f].

DISCUSSION

Calcium hydroxide has been the first choice material for apexification, with repeated changes over the course of 5-20 months to induce the formation of a calcific barrier.[20] The unpredictable and often lengthy course of this treatment modality presents challenges, including the vulnerability of the temporary coronal restoration to re-infection.[21] Moreover, the treatment requires a high level of patient compliance. For these reasons, one visit apexification has been suggested.[22] MTA introduced by Torabinejad and colleagues at Loma Linda University has shown promising results.[23] MTA has demonstrated minimal leakage of dye and bacteria in comparison with other restorative materials.[24] MTA, a bio-compatible material, can be used to create a physical barrier that also helps in formation of bone and periodontium around its interface.[25] With the use of MTA, the potential for fractures of immature teeth with thin roots is reduced, because a bonded core can be placed immediately within the root canal.

The major problem in cases of a wide open apex is the need to limit the material to the apex, thus avoiding the extrusion of a large amount of material into the periodontal tissue. A large volume of the extruded material may set before it disintegrates and gets resorbed. This might result in the persistence of the inflammatory process, which may complicate or even prevent repair of the tissue.[26-28] Using a matrix avoids the extrusion of the material into the periodontal tissues, reduces leakage in the sealing material, and allows favourable response of the periodontal tissues. Various materials have been used for the formation of matrix like calcium hydroxide, hydroxyapatite, resorbable collagen and calcium sulphate.[182930] For the application of MTA, no pressure-resistant support is necessary. Freshly mixed MTA has a soft consistency and may be applied without pressure. Moreover, MTA does not require a moisture-free environment as it sets in the presence of moisture. Some studies mention the use of small pieces of collagen membranes that are packed within the bone space to create a matrix against which MTA can be packed.[31]

Platelets are known to contain a variety of growth factors, including transforming growth factor β, vascular endothelial growth factor, and platelet-derived growth factor. These growth factors are released from the platelets when they are activated, secreted, or aggregated by collagen or epinephrine. PRF is an immune platelet concentrate, collecting on a single fibrin membrane all the constituents of a blood sample favourable to healing and immunity. PRF has been considered as a fibrin biomaterial. Its molecular structure with low thrombin concentration is an optimal matrix for migration of endothelial cells and fibroblasts. It permits a rapid angiogenesis and an easier remodelling of fibrin. It features all the necessary parameters permitting optimal healing. These consist of a fibrin matrix polymerized in a tetra molecular structure, the incorporation of platelets, leukocyte and cytokines, and the presence of circulating stem cells.[32] PRF stimulates osteoblasts, gingival fibroblasts, and periodontal ligament cells proliferation as a mitogen. Many growth factors such as platelet derived growth factors and transforming growth factors, are released from PRF. The properties of this natural fibrin biomaterial thus offer great potential during wound healing.[33] Moreover, PRF is totally autologus and will definitely be more biocompatible than any other material.

The combination of PRF as a matrix and MTA as an apical barrier could be considered as a good option for creating artificial root-end barriers. However, controlled clinical trials are necessary to investigate the predictability of the outcome of the technique.