Endodontic retreatment incisors previously treatedwith a conventional apexification protocol by Miguel Pizango

Aust Endod J 2011; 37: 31–35

C A S E R E P O RT

Endodontic retreatment of maxillary incisors previously treated with a conventional apexiﬁcation protocol: A case report Bill Kahler, DClinDent, PhD University of Queensland Dental School, Brisbane, Queensland, Australia

Keywords apexiﬁcation, calcium hydroxide, endodontic retreatment, mineral trioxide aggregate. Correspondence Dr Bill Kahler, University of Queensland Dental School, 200 Turbot Street, Brisbane, Qld. 4000, Australia. Email: w.kahler@uq.edu.au doi:10.1111/j.1747-4477.2011.00294.x

Abstract This case reports on the treatment of an immature tooth initially treated with calcium hydroxide apexification techniques. When the patient subsequently sought treatment for aesthetic concerns, the presence of apical periodontitis required revision of the endodontic procedure. Resolution of the periapical radiolucency was evident at a 12-month review. The use of mineral trioxide aggregate as an apical filling material and restoration with chemically cured composite resin extending into the coronal third of the root may prevent further contamination of the root canal system and strengthen the tooth.

Introduction Apexification with calcium hydroxide of necrotic immature teeth that have suffered a traumatic injury is a traditional procedure that aims to induce a hard calcific barrier at the apex so that a conventional root filling can be achieved (1,2). More recently, mineral trioxide aggregate (MTA) is often used as an apical filling material as it exhibits comparable healing outcomes and treatment can often be completed in one visit (3,4). An appropriate restoration that provides a coronal seal is an important consideration on the outcome of endodontic treatment (5). In addition, the final restoration should maintain the strength of the tooth so as to resist occlusal and parafunctional loads as well as compliment the aesthetics of the patient’s smile. This case presentation reports on an immature tooth initially treated with calcium hydroxide apexification techniques where retreatment was undertaken with MTA and an effective coronal seal was integral to the final outcome. Internal bleaching was able to achieve a pleasing aesthetic appearance of the previously discoloured tooth.

Case report A 14-year-old female patient initially presented to her dentist as she was concerned with the appearance of

her maxillary central incisors (Fig. 1). The teeth were accessed by her general dentist preparatory to internal bleaching at which time significant voids were noted with the root fill being poorly condensed. A periapical radiograph was then taken which revealed wide canals and a large periapical radiolucency associated with the right maxillary central incisor (Fig. 2). The diagnosis for the right maxillary central incisor was consistent with asymptomatic apical periodontitis. The patient was referred for specialist management. On examination, both teeth were asymptomatic. The presence of Class IV composite restorations as well as extensive enamel crazing revealed by illumination suggested a history of trauma. The patient’s father explained that she had a fall at age 7 years and the teeth had been restored with composite resin. This injury is consistent with uncomplicated crown fractures and this was confirmed when the patient’s records were acquired from her prior dentist. At age 9 years, the teeth became symptomatic requiring endodontic intervention that involved apexification techniques facilitated by long-term dressing with calcium hydroxide (Figs 3–5). Root filling was completed some 19 months after the initial endodontic treatment was instigated (Fig. 6). Voids along the lateral borders of the root of the right maxillary central incisor as well as the apical third of the root in the left maxillary central incisor are evident. However, endodontic retreatment was required when the patient sought an 31

Endodontic retreatment of maxillary incisors

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Figure 1 A photograph of the maxillary central incisor teeth that were discoloured from prior trauma.

Figure 3 A preoperative periapical radiograph taken prior to apexiﬁcation techniques. The composite resin restorations placed to restore the uncomplicated crown fractures are evident.

Figure 2 A periapical radiograph of the root-ﬁlled maxillary central incisors. A periapical radiolucency associated with the right maxillary central incisor is evident. Voids along the lateral borders of the root canal as well in the apical third of the left central incisor are present.

aesthetic consultation of her discoloured teeth as coronal leakage was implicated in the pathosis for the right maxillary central incisor and for the known underfill in the left maxillary central incisor (Fig. 2). The teeth were accessed without anaesthesia and gutta-percha removed using Gates Glidden burs 2–4. Chloroform was used to assist in the removal of the original root filling. The canals were prepared using copious irrigation with sodium hypochlorite and EDTA. The canal was dressed with calcium hydroxide and the access cavity closed with Cavit and glass ionomer cement. One month later, the patient reported that the teeth remained asymptomatic. The teeth were accessed and again irrigated with sodium hypochlorite. MTA (ProRoot; Dentsply Tulsa Dental, Johnson City, TN, USA) was placed in the apical 5 mm of the root canal (Fig. 7) using an operating microscope (OPMI Pico; Carl Zeiss 32

Figure 4 A periapical radiograph showing calcium hydroxide in the right maxillary central incisor. The presence of an open apex is noted for both maxillary incisors.

Surgical GmbH, Oberkochen, Germany). Then thermoplasticised gutta-percha (System B, SybronEndo, Orange, CA, USA) and AH26 was backfilled into the canal (Fig. 8). Intra-canal bleaching was commenced and bleached according to a research protocol incorporating acidified thiourea, a reductive bleaching agent with hydroxyl radical scavenging properties (6,7), followed by 30% hydrogen peroxide sealed into the pulp chamber. After two appointments, the aesthetic colour of the tooth was considered satisfactory (Fig. 9). The coronal third of the root canal and the access cavity was restored with a chemically cured composite resin (ParaCore, Coltene/ Whaledent AG, Altstätten, Switzerland) incorporating

B. Kahler

Endodontic retreatment of maxillary incisors

Figure 7 A periapical radiograph showing the 5 mm apical pugs with mineral trioxide aggregate used as a root-ﬁlling material. Figure 5 A periapical radiograph showing calcium hydroxide in both maxillary central incisors. The commencement of an apical calciﬁc barrier is visible.

Figure 8 A periapical radiograph showing the thermoplasticised guttapercha placed over the mineral trioxide aggregate.

Figure 6 A periapical radiograph of the root ﬁlling following the completion of the calcium hydroxide apexiﬁcation technique. The aforementioned voids in the root canal are noticeable.

size 140 gutta-percha points in the canal (Fig. 10). The gutta-percha points were places as the teeth were heavily restored and the patient was active in physical sporting pursuits; it was considered that post placement may be required for future restorative options. A 12-month review revealed a favourable healing outcome with resolution of the periapical radiolucency (Fig. 11).

Discussion The original apexification procedure had been successful (Fig. 5) with the formation of an apical calcific barrier

and root fill (Fig. 6). Multiple appointments were required to complete apical closure at the apex over a 19 month time period. Sheehy and Roberts reported an average length of time for the formation of a calcific apical barrier ranging from 5 to 20 months (8). The calcific barrier induced at the apex following placement of long-term calcium hydroxide dressings consists of a layer of dense acellular cementum-like tissue surrounded by dense fibro-collagenous connective tissue containing foreign material and other calcific tissue (9). While clinical and radiographic evidence suggests this barrier is complete, histological analysis reveals that this barrier is porous (10). Yet, it is more likely that the apical periodontitis (Fig. 2) originated from coronal leakage. While this could be because of an ineffective seal provided by the existing composite resin restorations it may also have 33

Endodontic retreatment of maxillary incisors

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Figure 9 A photograph taken after the bleaching procedure revealing a pleasing aesthetic result.

Figure 11 A periapical radiograph taken at the 12 month review appointment. A favourable healing outcome with resolution of the periapical radiolucency is evident.

Figure 10 A periapical radiograph of the restoration of the access cavities with dual cured composite resin in the coronal third of the root canal to strengthen the root. Size 140 gutta-percha points have been placed centrally in the canal in case post placement is required if further prosthodontic treatment is required.

been from the many cracks and crazes evident in the crown of the tooth. Love et al. demonstrated that enamel/ dentine infractions can be pathways for bacterial invasion of the root canal system of traumatised teeth (11). This would therefore suggest that placement of an effective coronal restoration should extend into the root canal system so as to prevent contamination from enamel infractions often found in the crowns of teeth subjected to a traumatic injury. In this case, this was achieved with a chemically cured composite resin as these materials exhibit less polymerisation shrinkage than light-cured systems (12). Barkhodor and Kempler also reported less microleakage of endodontic access cavities with chemically cured composite resin compared to photopolymerising materials (13). MTA as a root canal filling material provides a significantly superior seal to gutta-percha in a saliva leakage 34

model (14). However, an apical plug of at least 4 mm is required for significant microleakage prevention (15). In this case the apical plug was 5 mm (Fig. 7). When MTA is placed in direct contact with the apical tissues, it has bio-inductive properties where hydroxyapatite forms on its surface to provide a biological seal (16). This is unlikely to have occurred in this case as apexification had been previously completed (Fig. 5). However, like calcium hydroxide, MTA creates an antibacterial environment by its alkaline pH which has a value of 10.2 after mixing and rising to 12.5 at 3 h (17). MTA has also been shown to maintain a high pH between 11 and 12 for an extended period of time of 78 days which is thought to be a consequence of ongoing low solubility of the material allowing continued formation of calcium hydroxide (18). While it is generally advocated that a moist cotton pellet be placed on the MTA to facilitate the setting of the material over a mean time of 165 âŤž 5 min (17), in this case obturation of the root canal was immediately completed with thermo-plasticised gutta-percha (Fig. 8) to minimise the number of appointments. Other authors have also reported that the use of a moistened cotton pellet is not required (19). Prior to the commencement of treatment, the patient and her father were informed of the higher incidence of root fractures associated with traumatised anterior teeth because of the cessation of root development (20). In this case, the roots were restored with dual cure composite resin as this has been shown to strengthen thin dentinal walls and reduce the fracture susceptibility of the roots (21,22). It is important that the patient be aware that eventual loss of the tooth may occur. A limitation of apexification techniques is that no further growth of the

ÂŠ 2011 The Author Australian Endodontic Journal ÂŠ 2011 Australian Society of Endodontology

B. Kahler

root usually occurs with the loss of pulp vitality. A paradigm shift in the treatment of immature non-vital teeth has occurred with new protocols that disinfect the root canal space with a tri-antibiotic paste followed by irritation of the periapical tissues to create haemorrhage in the canal. This regenerative endodontic technique allows continued root maturation which may mean that apexification is no longer indicated as a clinical treatment (23,24).

Conclusion This case reports on the treatment of an immature root initially treated with calcium hydroxide apexification techniques. When the patient sought treatment for aesthetic concerns, the presence of apical periodontitis required revision of the endodontic procedure. The use of MTA as an apical filling material and restoration with chemically cured composite resin extending into the coronal third of the root may prevent further contamination of the root canal system and strengthen the tooth.

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Endodontic retreatment of maxillary incisors

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