Endodontic retreatment incisors previously treatedwith a conventional apexification protocol

CASE REPORT

Endodontic retreatment of maxillary incisors previously treatedwith a conventional apexification protocol: A case reportBill Kahler, DClinDent, PhD

University of Queensland Dental School, Brisbane, Queensland, Australia

Keywordsapexification, calcium hydroxide, endodontic

retreatment, mineral trioxide aggregate.

CorrespondenceDr Bill Kahler, University of Queensland Dental

School, 200 Turbot Street, Brisbane, Qld. 4000,

Australia. Email: [email protected]

doi:10.1111/j.1747-4477.2011.00294.x

Abstract

This case reports on the treatment of an immature tooth initially treated withcalcium hydroxide apexification techniques. When the patient subsequentlysought treatment for aesthetic concerns, the presence of apical periodontitisrequired revision of the endodontic procedure. Resolution of the periapicalradiolucency was evident at a 12-month review. The use of mineral trioxideaggregate as an apical filling material and restoration with chemically curedcomposite resin extending into the coronal third of the root may preventfurther contamination of the root canal system and strengthen the tooth.

Introduction

Apexification with calcium hydroxide of necrotic imma-ture teeth that have suffered a traumatic injury is a tra-ditional procedure that aims to induce a hard calcificbarrier at the apex so that a conventional root filling canbe achieved (1,2). More recently, mineral trioxide aggre-gate (MTA) is often used as an apical filling material as itexhibits comparable healing outcomes and treatment canoften be completed in one visit (3,4). An appropriaterestoration that provides a coronal seal is an importantconsideration on the outcome of endodontic treatment(5). In addition, the final restoration should maintain thestrength of the tooth so as to resist occlusal and parafunc-tional loads as well as compliment the aesthetics of thepatient’s smile. This case presentation reports on animmature tooth initially treated with calcium hydroxideapexification techniques where retreatment was under-taken with MTA and an effective coronal seal was integralto the final outcome. Internal bleaching was able toachieve a pleasing aesthetic appearance of the previouslydiscoloured tooth.

Case report

A 14-year-old female patient initially presented to herdentist as she was concerned with the appearance of

her maxillary central incisors (Fig. 1). The teeth wereaccessed by her general dentist preparatory to internalbleaching at which time significant voids were noted withthe root fill being poorly condensed. A periapical radio-graph was then taken which revealed wide canals and alarge periapical radiolucency associated with the rightmaxillary central incisor (Fig. 2). The diagnosis for theright maxillary central incisor was consistent with asymp-tomatic apical periodontitis. The patient was referred forspecialist management. On examination, both teeth wereasymptomatic. The presence of Class IV composite resto-rations as well as extensive enamel crazing revealed byillumination suggested a history of trauma. The patient’sfather explained that she had a fall at age 7 years and theteeth had been restored with composite resin. This injuryis consistent with uncomplicated crown fractures and thiswas confirmed when the patient’s records were acquiredfrom her prior dentist. At age 9 years, the teeth becamesymptomatic requiring endodontic intervention thatinvolved apexification techniques facilitated by long-termdressing with calcium hydroxide (Figs 3–5). Root fillingwas completed some 19 months after the initial endodon-tic treatment was instigated (Fig. 6). Voids along thelateral borders of the root of the right maxillary centralincisor as well as the apical third of the root in the leftmaxillary central incisor are evident. However, endodon-tic retreatment was required when the patient sought an

Aust Endod J 2011; 37: 31–35

31© 2011 The Author

Australian Endodontic Journal © 2011 Australian Society of Endodontology

aesthetic consultation of her discoloured teeth as coronalleakage was implicated in the pathosis for the right max-illary central incisor and for the known underfill in theleft maxillary central incisor (Fig. 2).

The teeth were accessed without anaesthesia andgutta-percha removed using Gates Glidden burs 2–4.Chloroform was used to assist in the removal of theoriginal root filling. The canals were prepared usingcopious irrigation with sodium hypochlorite and EDTA.The canal was dressed with calcium hydroxide and theaccess cavity closed with Cavit and glass ionomercement. One month later, the patient reported that theteeth remained asymptomatic. The teeth were accessedand 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

Surgical GmbH, Oberkochen, Germany). Then thermo-plasticised gutta-percha (System B, SybronEndo, Orange,CA, USA) and AH26 was backfilled into the canal(Fig. 8). Intra-canal bleaching was commenced andbleached according to a research protocol incorporatingacidified thiourea, a reductive bleaching agent withhydroxyl radical scavenging properties (6,7), followed by30% hydrogen peroxide sealed into the pulp chamber.After two appointments, the aesthetic colour of the toothwas considered satisfactory (Fig. 9). The coronal third ofthe root canal and the access cavity was restored with achemically cured composite resin (ParaCore, Coltene/Whaledent AG, Altstätten, Switzerland) incorporating

Figure 1 A photograph of the maxillary central incisor teeth that were

discoloured from prior trauma.

Figure 2 A periapical radiograph of the root-filled maxillary central inci-

sors. 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.

Figure 3 A preoperative periapical radiograph taken prior to apexifica-

tion techniques. The composite resin restorations placed to restore the

uncomplicated crown fractures are evident.

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.

Endodontic retreatment of maxillary incisors B. Kahler

32 © 2011 The Author


size 140 gutta-percha points in the canal (Fig. 10). Thegutta-percha points were places as the teeth were heavilyrestored and the patient was active in physical sportingpursuits; it was considered that post placement may berequired for future restorative options. A 12-monthreview revealed a favourable healing outcome with reso-lution 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 wererequired to complete apical closure at the apex over a19 month time period. Sheehy and Roberts reported anaverage length of time for the formation of a calcificapical barrier ranging from 5 to 20 months (8). The cal-cific barrier induced at the apex following placement oflong-term calcium hydroxide dressings consists of a layerof dense acellular cementum-like tissue surroundedby dense fibro-collagenous connective tissue containingforeign material and other calcific tissue (9). While clini-cal and radiographic evidence suggests this barrier is com-plete, histological analysis reveals that this barrier isporous (10). Yet, it is more likely that the apical periodon-titis (Fig. 2) originated from coronal leakage. While thiscould be because of an ineffective seal provided by theexisting composite resin restorations it may also have

Figure 5 A periapical radiograph showing calcium hydroxide in both

maxillary central incisors. The commencement of an apical calcific barrier

is visible.

Figure 6 A periapical radiograph of the root filling following the comple-

tion of the calcium hydroxide apexification technique. The aforemen-

tioned voids in the root canal are noticeable.

Figure 7 A periapical radiograph showing the 5 mm apical pugs with

mineral trioxide aggregate used as a root-filling material.

Figure 8 A periapical radiograph showing the thermoplasticised gutta-

percha placed over the mineral trioxide aggregate.

B. Kahler Endodontic retreatment of maxillary incisors



been from the many cracks and crazes evident in thecrown of the tooth. Love et al. demonstrated that enamel/dentine infractions can be pathways for bacterial invasionof the root canal system of traumatised teeth (11). Thiswould therefore suggest that placement of an effectivecoronal restoration should extend into the root canalsystem so as to prevent contamination from enamelinfractions often found in the crowns of teeth subjected toa traumatic injury. In this case, this was achieved with achemically cured composite resin as these materialsexhibit less polymerisation shrinkage than light-curedsystems (12). Barkhodor and Kempler also reportedless microleakage of endodontic access cavities withchemically cured composite resin compared to photo-polymerising materials (13).

MTA as a root canal filling material provides a signifi-cantly superior seal to gutta-percha in a saliva leakage

model (14). However, an apical plug of at least 4 mm isrequired for significant microleakage prevention (15). Inthis case the apical plug was 5 mm (Fig. 7). When MTA isplaced in direct contact with the apical tissues, it hasbio-inductive properties where hydroxyapatite forms onits surface to provide a biological seal (16). This is unlikelyto have occurred in this case as apexification had beenpreviously completed (Fig. 5). However, like calciumhydroxide, MTA creates an antibacterial environment byits alkaline pH which has a value of 10.2 after mixing andrising to 12.5 at 3 h (17). MTA has also been shown tomaintain a high pH between 11 and 12 for an extendedperiod of time of 78 days which is thought to be a con-sequence of ongoing low solubility of the material allow-ing continued formation of calcium hydroxide (18).While it is generally advocated that a moist cotton pelletbe placed on the MTA to facilitate the setting of thematerial over a mean time of 165 � 5 min (17), in thiscase obturation of the root canal was immediately com-pleted with thermo-plasticised gutta-percha (Fig. 8) tominimise the number of appointments. Other authorshave also reported that the use of a moistened cottonpellet is not required (19).

Prior to the commencement of treatment, the patientand her father were informed of the higher incidence ofroot fractures associated with traumatised anterior teethbecause of the cessation of root development (20). In thiscase, the roots were restored with dual cure compositeresin as this has been shown to strengthen thin dentinalwalls and reduce the fracture susceptibility of the roots(21,22). It is important that the patient be aware thateventual loss of the tooth may occur. A limitation ofapexification techniques is that no further growth of the

Figure 9 A photograph taken after the bleaching procedure revealing a

pleasing aesthetic result.

Figure 10 A periapical radiograph of the restoration of the access cavi-

ties 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 prosth-

odontic treatment is required.

Figure 11 A periapical radiograph taken at the 12 month review appoint-

ment. A favourable healing outcome with resolution of the periapical

radiolucency is evident.

Endodontic retreatment of maxillary incisors B. Kahler

34 © 2011 The Author


root usually occurs with the loss of pulp vitality. A para-digm shift in the treatment of immature non-vital teethhas occurred with new protocols that disinfect the rootcanal space with a tri-antibiotic paste followed by irrita-tion of the periapical tissues to create haemorrhage in thecanal. This regenerative endodontic technique allowscontinued root maturation which may mean that apexi-fication is no longer indicated as a clinical treatment(23,24).

Conclusion

This case reports on the treatment of an immature rootinitially treated with calcium hydroxide apexificationtechniques. When the patient sought treatment for aes-thetic concerns, the presence of apical periodontitisrequired revision of the endodontic procedure. The useof MTA as an apical filling material and restorationwith chemically cured composite resin extending intothe coronal third of the root may prevent further con-tamination of the root canal system and strengthen thetooth.

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B. Kahler Endodontic retreatment of maxillary incisors



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Endodontic retreatment incisors previously treatedwith a conventional apexification protocol