Repair of incomplete horizontal mid-root fracture of maxillary central incisor with mineral trioxide aggregate: A follow up report.

Incomplete horizontal fractures occur in teeth with developing root as it cannot withstand traumatic force during injury. Diagnosis and management of such cases are difficult. Cone Beam Computed Tomography (CBCT) served as efficient diagnostic tool and follow up measure and the use of Mineral Trioxide Aggregate in treatment had shown a better prognostic importance. In present case, treatment outcome of one year is reported in incompletely fractured mid-root of central incisor and the clinical approach is discussed.

INTRODUCTION

Root fractures in permanent teeth are uncommon injuries, seen mostly in children and show complex healing patterns. Horizontal root fracture ranges from 0.5-7% in permanent teeth.[1] Mid-root fractures frequently occur in anterior teeth due to their position in the arch. These are transverse to oblique and single or multiple, complete or incomplete.[2] Diagnosis of incomplete root fracture is time consuming and complex.

Cone beam computed tomography (CBCT) or Cone beam volumetric tomography (CBVT) is proven adjunct to traditional intraoral radiograph in detection of fractured root. As compared to medical computed tomography (CT), CBVT provides scan-time prevention, radiation dose reduction, and affordability to patient.[3] Prognosis of management of fractured teeth depends on several factors, such as degree of dislocation, stage of root formation, location of fracture, time period between trauma, and treatment, type of dental trauma and displacement of the coronal fragment compared with no displacement of the coronal fragment.[4] Healing of fracture can take place by interposition of calcified tissue, interposition of connective tissue or interposition of bone tissue depending on the health of the pulp, dentine, cementum, and alveolar bone and the degree of dislocation of the fragments.[5]

Treatment of the root canal with calcium hydroxide followed by filling with gutta percha is one of the conservative ways to manage horizontally fractured root.[6] In case of pulpal necrosis, calcium hydroxide may provide a hard tissue barrier at the apical end of the coronal part of the fracture. But this procedure is time consuming, may require 7-8 months, for apical bridge formation.[7]

To overcome drawbacks, many alternative approaches have been suggested to develop a one-step procedure for the completion of the endodontic treatment. One of these alternatives is mineral trioxide aggregate (MTA). MTA has superior biocompatibility, sealing ability and less cytotoxicity than other materials used in pulpal therapy. It promotes the overgrowth of cementum and may facilitate the regeneration of the periodontal ligament because of its alkaline pH of 12.5 and the presence of several mineral oxides in its composition.[8] It sets fast to a hard consistency after mixing and insertion, thus allowing early completion of final treatment when acting as artificial barrier.

CASE REPORT

An 8-years-old female patient had reported with pain and slight swelling in anterior region of jaw. She had a history of trauma 4 months back during playing at school, with a fractured maxillary right central incisor. Clinical examination showed Ellis type 2 fracture with swelling and tenderness in the periapical region of maxillary right central incisor. Pulp vitality tests showed negative response. The adjacent teeth responded positive and within normal limits to cold stimulation. Radiograph revealed periapical radiolucency with incomplete apex formation in relation with maxillary right central incisor [Figure 1a]. On the basis of clinical and radiographic observations pulpal status was determined as non-vital due to trauma. The root canal treatment with MTA apexification was planned.

Figure 1

(a) preoperative radiograph (b) after placement of MTA (c) immediate post operative radiograph (d) one year follow up radiograph; (e and h) preoperative CBVT showing fracture line on buccal surface of root (f and i) immediate postoperative CBVT after obturation; (g and j) CBVT after one year showing healing of lesion and bone formation

Access cavity was prepared under rubber dam isolation. After extirpation of necrosed pulp, canal was instrumented and irrigated with 0.5% sodium hypochlorite. During determination of working length (WL), apex locator (Root ZX, J Morita, USA Inc.) indicated a very short WL as compared to radiographic WL. To rule out the possibility of mid- root fracture of maxillary right central incisor, CBVT was performed which revealed an unusual fracture of only buccal wall of root with almost complete resorption of buccal cortical bone. Radiolucency was seen adjacent to buccal part of root showing resorption of buccal cortical bone [Figure 1e and h].

After determination of WL, canal was completely instrumented and irrigated frequently with 0.5% sodium hypochlorite. Intracanal Calcium hydroxide (Metapex, Meta Biomed, South Korea) was placed in canal for two weeks. On the next visit, canal was irrigated with 3% sodium hypochlorite and MTA (MTA-Angelus, Londrina, PR, Brazil) was placed to seal fractured buccal portion and open apical end of maxillary right central incisor [Figure 1b]. The remaining root canal space was subsequently obturated with gutta percha [Figure 1c] and coronal sealing was done with core build up composite restorative material (Luxacore, DMG, Germany). Post-treatment CBVT was performed to confirm sealing [Figure 1f and i]. A follow-up radiograph and DVT was again performed after 12 months which showed intact sealing and complete healing of buccal defect with the bone formation [Figure 1d, g, j].

DISCUSSION

Root fractures heal differently depending on the degree of separation of the fragments, the severity of injury, and the ability of the pulp to heal. When the pulp-tissue vitality is preserved, the odontoblasts and the cells from the cementum are usually responsible for the healing process. If the dental pulp is necrotic, repair does not occur without root canal treatment.[9] Usually apical part of fractured tooth remains vital when pulp necrosis develops.[10] Hence, only coronal fragment is endodontically treated. But it is difficult to achieve the apical stop and seal the fractured fragment.

In present case, horizontal fracture was incomplete involving only buccal portion of immature root surface without any displacement of fractured fragment. Therefore, root canal treatment of entire root was planned with apexification.

Routinely, conventional intraoral periapical radiograph can reveal horizontal fracture line. But in present case as fracture was incomplete and on buccal aspect, therefore could not be detected on periapical radiograph. CBVT technology is appropriate option in such cases as it enables the clinician to observe an area in three different planes and acquire 3D information. It is observed that CBVT provides additional and clinically relevant information not found in the periapical radiographs. It has higher sensitivity, positive predictive value, and diagnostic accuracy than intraoral radiography. CBVT has major benefit of elimination of superimposition of anatomical structures which allows the clinician to analyze the fracture clearly.[11] Hence, CBVT was used in the present case as follow-up tool to observe treatment outcome.

The healing of horizontal root fractures seems to involve hard tissue deposition in and around the fracture site. Traditionally calcium hydroxide is used for achieving the calcified barrier. The most important problem with this material is the duration of the therapy, which is from 3-21 months.[12] Recently MTA is gaining more acceptance in alternative approaches. MTA shows less leakage, better antibacterial properties, high marginal adaptation, short setting time (~4 hours), a pH of 12.5 and is more biocompatible.[8] MTA can induce the release of growth factors such as bone morphogenetic proteins (BMPs), platelet derived growth factor (PDGF), fibroblast growth factor (FGF), transforming growth factor (TGF), insulin-like growth factor-1 (IGF-1), epidermal growth factor (EGF), cementum derived growth factor (CGF) from cementum matrix along with IGFs, TGF-β, BMPs, FGF, and PDFG from alveolar bone matrix and signal progenitor/stem cells in the periodontal ligament and alveolar bone marrow to differentiate into cementoblast-like cells and osteoblasts.[13] It reinforces and increases the fracture resistance of the thin dentinal wall. MTA can be used in teeth with pulp necrosis and inflamed periapical lesions because it may set in moist environments.[14] Hence, MTA was chosen as material of choice in this case. In MTA plug technique, root canals must be disinfected with temporary calcium hydroxide dressing before placing MTA for 2 weeks as chemo-mechanical preparation does not ensure complete elimination of microorganisms.[15] Hence, we used calcium hydroxide dressing for two weeks in this case. After this, MTA was placed sealing fracture line and closing the open apical end of canal. 1-year clinical and CBVT follow-up showed complete healing and regeneration of bone.

CONCLUSION

Mid-root fractures are complex injuries, often difficult to diagnose if it is incomplete. With the advent of new diagnostic tools and improved biomaterials, better prognosis can be expected. Though the long term follow up of patients with injuries is important to justify the prognosis, CBVT and MTA appears to be a viable and good option to diagnose and manage such cases.