Management Of Crown Root Fracture Of Maxillary Central Incisors – A Multidisciplinary Approach: A Case Report And An Overview

INTRODUCTION

           Most dental trauma occurs primarily in the anterior region of the mouth, affecting the maxilla more commonly than the mandible. Therefore, management and consequences of these injuries are multifactorial. The incidence of complicated crown root fractures ranges from 2% to 13% of all dental injuries and the most commonly involved teeth are the maxillary central incisors. The difficulties of the restoration depend on the type of fracture, the type of occlusion and the prognosis.¹

           Complicated crown root fracture can be defined as a fracture involving enamel, dentin, root structure and involving the pulp. It is noted that while esthetics, function, and cost are the core of patient's motivation, these goals may conflict with the goal of self preservation. In the case of fractured anterior teeth, especially one with a complicated crown root fracture, it is not uncommon for a dentist to recommend sacrificing the tooth and placing an implant. Unfortunately, traumatic injuries to the alveolus or extractions can cause a loss of buccal alveolar bone.

           This clinical case report describes a multi disciplinary treatment approach for the management of complicated crown root fracture of maxillary central incisors.

CASE REPORT

           A 26 year-old female patient visited the Department of Conservative Dentistry and Endodontics, A.B. Shetty Memorial Institute of Dental Sciences, Mangalore, with a chief complaint of broken teeth in the upper front region of the mouth (Figure-1).

History revealed that the patient had met with a road traffic accident a week earlier following which fracture of maxillary right (11) and left central incisor (21) had occurred. The patient visited nearby medical practitioner immediately after trauma for treatment and then she was referred for the dental treatment, in A.B. Shetty Memorial Institute of Dental Sciences, Mangalore.

Extra oral examination revealed no significant findings. Face was symmetric with a straight profile.

Dental examination revealed that the mesial half of crown of maxillary right central incisor was fractured and maxillary left central incisor had an oblique fracture line extending distally involving mid portion of the tooth, with fractured fragment still in place. The fractured fragment of maxillary left central incisor was removed (Figure 2).

Periodontal examination revealed that the gingiva was firm and the papillae were intact around the fractured right and left central incisors. Both the teeth were not tender on percussion and no mobility was seen. Clinical examination revealed an adequate amount of attached gingiva. Full mouth intra oral radiographs indicated that the patient had not suffered alveolar fractures and the trauma was limited to the maxillary central incisors. Radiographic examination confirmed the findings of the clinical examination (Figure-3); the fracture line on palatal side could be traced 2mm below the alveolar crest, for both the central incisors. The periapical view showed closed apex in relation to maxillary right and left central incisors. Pulp vitality tests revealed that the adjacent teeth were unaffected. On the basis of clinical and radiographic findings, a diagnosis of complicated crown root fracture for tooth number 11 and 21 was made (N 873.64 – Andreasen modification of WHO classification).¹

Tooth fracture below the gingival attachment or alveolar bone crest presents restorative difficulties. As with periodontal probing it wasnoticed that the biologic width was violated by the crown root fracture of maxillary right and left central incisors; at the same time there was inadequate tooth structure to achieve a ferrule effect following reconstruction with a post-core and crown.

Different treatment options considered were,

1) Extraction of maxillary right and left central incisors, and placing an implant.

2) Extraction of maxillary right and left central incisors, and placing a fixed prosthesis and

3) Endodontic therapy, orthodontic extrusion, reconstruction with a post-core and fixed prosthesis.

           After reviewing the risks and potential outcomes, the patient opted for orthodontic extrusion of both the teeth and reconstruction with a post-core and fixed prosthesis.

           A definitive treatment plan was made as follows: endodontic therapy for both the teeth, orthodontic extrusion of 11 and 21 was planned, to move the fracture line 4mm above the alveolar crest, in order to regain the lost biologic width.

Root canal therapy was performed for both the teeth. The canals were obturated using lateral condensation technique and post space was prepared for maxillary right and left central incisors. The J shape hook was cemented in the root canal of both the central incisors with zinc phosphate cement (Figure-4). At the end of three weeks, both the teeth were extruded about 3mm (Figure-5). The teeth were stabilized for about four weeks by ligating the 'J' hook and the archwire with a ligature wire. After orthodontic extrusion, it was observed that the fracture line was still subgingival and also gingival margin moved coronally. Hence, periodontal therapy was performed during the stabilization period. A flap was raised with a crevicular and two vertical releasing incisions. Osseous recontouring was done for the purpose of increasing the crown length and maintaining the biologic width. Flap was apically displaced, repositioned at the level of crest of the alveolar bone and sutured.

           After 4 weeks, J hook and the arch wire was removed, wax pattern was prepared, a custom made gold post and core was cemented with glass ionomer luting cement (Figure-6 and 7). Finally both the teeth were restored with porcelain fused metal crowns with a metal mesh extending on to the adjacent teeth on the palatal surface in order to avoid any chances of intrusion of the teeth 11 and 21 (Figure-8).

DISCUSSION

           Crown-root fractures have immediate implications for endodontic, restorative and periodontal prognosis due to the line of fracture, which is subgingival. Treatment objective must, therefore, be aimed at exposing the fracture margins supragingivally, so that all clinical procedures can be managed successfully.³

           There are several options for the treatment of crown root fracture involving the biologic width which include: fragment removal only, fragment removal and gingivectomy, orthodontic extrusion, surgical extrusion of apical fragment or tooth extraction in severe cases.⁵

           Forced orthodontic extrusion is generally advocated for treating coronal and root fractures, root caries and endodontic perforations that are slightly above the crestal bone height.⁴However, if the loss of tooth structure is at the gingival margin or below the crest of the bone, exposure of sound tooth structure becomes paramount in order to achieve: restoration margins on sound tooth structure, maintenance of the biologic width, access for impression techniques, control of hemorrhage, control of moisture, restoration of function and esthetics.⁵

           After the tooth has erupted, it must be stabilized to prevent it from intruding back into the alveolus. The reason for reintrusion is the orientation of the principal fibres of the periodontium. During forced eruption, the periodontal fibres become oriented obliquely and stretched as the tooth root moves coronally. These fibres eventually will reorient themselves after about 6 months. Before this time, the tooth root can reintrude significantly. Therefore, if this type of treatment is performed, an adequate period of stabilization is necessary to avoid significant relapse and reintrusion of the root.⁴

           In some situations fracture may extend beneath the level of the alveolar ridge. In these cases the restoration of the fractured crown becomes difficult because the tooth preparation would extend to the level of bone.⁶This overextension could result in an invasion of the biologic width of the tooth and cause persistent inflammation of the marginal gingiva. In these situations, it may be beneficial to cause eruption of the fractured tooth and move the fractured margin coronally, so that it can be restored without causing gingival inflammation. However if the fracture is severe, it may be better to extract the tooth and replace it with an implant or fixed prosthesis. The orthodontists, restorative dentist and periodontist should evaluate six criteria to determine if the tooth should be extruded or extracted. The criteria's are, root length, root form, level of fracture, relative importance of the tooth, esthetics and endodontic or periodontal prognosis.⁴

           In case of a fractured anterior teeth, especially one with a complicated crown root fracture, it is not uncommon for a dentist to recommend sacrificing the tooth and placing an implant. Orthodontic extrusion provides both the dentist and the patient with another opportunity to use the natural root system and prevent premature sacrifice of tooth. It is a conservative approach that saves the root system, maintains periodontal architecture and esthetics.

CONCLUSION

           The expanding role of endodontics into more phases of dental treatment is illustrated by the awareness of relationships with other specialities. Restoration of traumatized teeth requires a close collaboration between different dental specialties.

           Adjunctive orthodontic root extrusion and root separation are essential clinical procedures that will enhance the integrated treatment planning process of tooth retention in endodonticorthodontic related cases. Extrusion of a fractured tooth has several advantages over extraction and prosthodontic replacement. It is a conservative approach that preserves the natural tooth and main tain s th e p er io d o n tal ar ch itectu r e. Disadvantage of the approach is the long treatment duration compared to extraction and replacement.

           The present case report is a multidisciplinary approach for the management of crown root fracture of maxillary central incisors, leading to conservation of teeth and its permanent restoration.