Young AEJ2007

2007 POSTGRADUATE CASE REPORT COMPETIT ION WINNER

Contemporary management of lateral root perforationdiagnosed with the aid of dental computed tomographyGeoffrey R. Young, BDS, DClinDent

School of Dental Science, University of Melbourne, Melbourne, Victoria, Australia

Keywordscone beam computed tomography, diagnostic

imaging, mineral trioxide aggregate,

perforation repair, root perforation.

CorrespondenceDr Geoffrey Young, School of Dental Science,

University of Melbourne, 720 Swanston St,

Melbourne, Vic. 3010, Australia. Email:

[email protected]

doi: 10.1111/j.1747-4477.2007.00098.x

Abstract

Lateral root perforation unnoticed during post-space preparation, and followedby post cementation, can subsequently be challenging to diagnose in thelabio-lingual plane due to the two-dimensional nature of conventional radi-ography. This paper demonstrates the application of a recently developedthree-dimensional imaging system, cone beam computed tomography, in thediagnosis of iatrogenic root perforation. A clinical case is reported where labialpost perforation in a maxillary central incisor occurring 15 years previouslypresented with a sinus tract and radiolucent lesion. Non-surgical retreatmentand perforation repair using mineral trioxide aggregate was performed withthe aid of an operating microscope. The sinus tract resolved with radiographicevidence of healing at 1-year recall.

Introduction

Root perforation refers to the creation of a communica-tion between the root canal system and the peri-radiculartissues (1). While this may occur due to root resorption, itis most commonly a result of iatrogenic damage sustainedduring preparation of endodontic access cavities, rootcanal shaping, and during post-space preparation (2).Such a communication creates the potential for aninflammatory lesion with destruction of the adjacentperiodontal tissues. The prognosis for teeth with rootperforation depends foremost on the prevention orcontrol of bacterial infection at the perforation site (1). Inaddition, use of a biocompatible repair material to providethe best possible seal against penetration of bacteria willlimit periodontal inflammation.

Lateral root perforations, caused accidentally andunnoticed during post-space preparation, typically showlateral bone defects on recall radiographs (3). Successfultreatment of such defects depends on elimination ofbacteria from the root canal system and perforation site.While post perforations can be repaired non-surgically,surgically or from both approaches (4), it is non-surgicalmanagement that has the greatest potential to achievemicrobial control. This requires removal of the post andthe potentially infected root canal filling, followed by

chemomechanical debridement and shaping of the rootcanal (3). Mineral trioxide aggregate (MTA) is a suitableperforation repair material due to its excellent bio-compatibility (5,6) and sealing ability (7,8), which is notaffected by blood contamination (9). This material has theunique ability to promote regeneration of cementum andperiodontal ligament (5,6,10).

Accurate preoperative determination of the presence ofa root perforation is important for evaluating prognosisand treatment planning. Radiographic detection towardthe labial or lingual root surface is challenging, becausethe image of the perforation is superimposed on thatof the root. Taking preoperative radiographs from twodifferent horizontal angles (tube shift technique) canfacilitate identification of a labio-lingually misdirectedpost (11). However, the greatest limitation of conven-tional radiography is the inability to fully describe thethree-dimensional (3-D) anatomy of teeth and theirrelated structures (12). In recent years, a new method,cone beam computed tomography (CBCT) has beenintroduced specifically for dental applications (13,14).CBCT is a 3-D imaging technique where a small cone-shaped X-ray beam is directed through the area of interestand onto an opposing X-ray detector while making a360-degree rotation about the patient’s head (12). Duringthe scan, a series of exposures or projections is acquired

Aust Endod J 2007; 33: 112–118

112 © 2007 The Author

Journal compilation © 2007 Australian Society of Endodontology

mailto:[email protected]

which provides the raw data for reconstruction of theexposed volume by computer algorithm. Multi-planarreconstruction of the primary data allows for both 3-Dimages and two-dimensional (2-D) images of any selectedplane to be made. At a radiation dose similar to that fromtwo to three intraoral radiographs (15), the CBCT methodprovides considerably more information for oral diagnos-tic purposes (12).

This case report demonstrates the use of CBCT as aneffective diagnostic tool for the assessment of post perfo-rations, and describes the non-surgical repair of a postperforation in the middle third of the root of a maxillarycentral incisor using MTA with the aid of an operatingmicroscope.

Case report

A healthy 51-year-old female patient was referred to theEndodontic Department of the Royal Dental Hospital ofMelbourne for consultation and treatment concerningtooth 21. The patient’s dental history indicated that tooth21 had been endodontically treated along with severalother teeth approximately 15 years previously. An exten-sive fixed prosthesis was then constructed, spanning fromtooth 15 to tooth 27, with all units fused together by themetal substructure (Fig. 1). Following this treatment, thepatient had been asymptomatic until mid-2005, when asinus tract was noticed labial to tooth 21.

On presentation, the patient reported no symptoms.Clinically, the dentition was heavily restored and thepatient’s oral hygiene was significantly hampered by themaxillary fixed prosthesis. The patient wore a mandibularremovable partial denture and there was a deep anterioroverbite. A sinus tract was present on the labial attachedgingiva adjacent to tooth 21 (Fig. 2), which traced with a

gutta-percha cone toward the lateral root surface of thistooth (Fig. 3). Tooth 21 was not tender to percussion;however, the labial mucosa related to the area was tenderto palpation. No abnormal probing depths were detected.Radiographic examination showed that tooth 21 con-tained a post, and a well-compacted root filling extendingclose to the radiographic apex (Fig. 3). There was loss oflamina dura with an associated radiolucent lesion on thedistal aspect of the root, corresponding to the apical levelof the post. A horizontal tube shift radiograph (Fig. 4)

Figure 1 Preoperative panoramic radiograph showing extensive fixed

prosthesis spanning from tooth 15 to tooth 27. All units were fused

together.

Figure 2 Preoperative photograph showing draining sinus tract on the

attached gingiva labial to tooth 21.

Figure 3 Preoperative radiograph showing gutta-percha cone tracing a

sinus tract to the lateral aspect of tooth 21.

G. Young Management of Lateral Root Perforation

113© 2007 The Author


demonstrated that the post did not follow the long axis ofthe root, but rather was misdirected labially. Also notedwere periapical radiolucent lesions associated with teeth12 and 42.

A diagnosis of suppurative periradicular abscess wasmade for tooth 21. Possible aetiologies included lateralroot perforation, root fracture or leaching of microbialirritants via a lateral canal. To ascertain more precisely the3-D relationship between post and root structure, CBCTimaging was performed using the 3D Accuitomo XYZSlice View Tomograph (3D Accuitomo, J. Morita Mfg.Corp, Kyoto, Japan). This imaging confirmed that tooth21 had a labial post perforation at mid-root level with anassociated bony defect (Fig. 5).

The overall dental status, including periodontal impli-cations of fused crowns, was discussed with the patient,and a recommendation was made to remove the existingfixed partial denture with a view to full-mouth rehabili-tation. As the patient declined to have the fixed prosthesisremoved, treatment options considered for tooth 21included: (i) root amputation with retention of the exist-ing fixed partial denture; (ii) surgical perforation repair;or (iii) internal perforation repair with MTA followed byconstruction of a new post-core and crown. The patientwas advised that an internal retreatment approach wasthe best option due to the greater ability to control intra-radicular infection. The patient accepted internal repair ofthe perforation with MTA.

After local anaesthesia and rubber dam isolation, thecrown on tooth 21 was sectioned from the adjacentcrowns using a high-speed diamond bur and removed.The post was loosened and removed with ultrasonicinstruments. Inspection with an operating micro-scope (Möller Denta 300, Möller-Wedel GmbH, Wedel,Germany) confirmed a labial root perforation (approxi-mately 0.5 ¥ 1 mm). There was no evidence of root frac-ture and the remaining tooth structure was restorable,with 2 mm of supragingival dentine available for a ferrule(16). The perforation was cleaned with a small pulp burin a slow-speed handpiece and rinsed gently with 1%sodium hypochlorite. Cavit (ESPE, Dental AG, Norris-town, PA, USA) was used to temporarily seal the perfo-ration prior to removal of the existing root filling withhand files and chloroform (Fig. 6). The perforation wassealed at this early stage to control bleeding into thecanal, to confine irrigation and infected root filling mate-rial, and to permit controlled compaction of the newroot filling. Definitive perforation repair with MTA wasdelayed due to the risk of disrupting the material duringcanal preparation and obturation procedures.

Working length was confirmed by using both a radio-graph and an electronic apex locator (Tri-Auto ZX,J. Morita Mfg. Corp). The root canal was cleaned andshaped using ProFile rotary instruments (Dentsply TulsaDental, Johnson City, TN, USA) under copious irrigationwith 1% sodium hypochlorite solution. The canal wasprepared to size #60 and dressed with calcium hydroxidepaste (Pulpdent Corp., Watertown, MA, USA) beforesealing the coronal access with Cavit and Fuji IX (Kerr

Figure 4 Horizontal (mesial) tube shift radiograph showing that the post

in tooth 21 was misdirected labially.

Figure 5 Coronal sectional image through tooth 21 obtained by the 3D

Accuitomo (slice thickness 1 mm). The post perforates the labial root

surface. Associated expansion of a periradicular lesion with discontinuity

of the labial cortical bone is evident.

Management of Lateral Root Perforation G. Young



Corp., Orange, CA, USA). A vacuum-formed removableprosthesis was issued as an interim measure (Fig. 7).

The patient returned 2 weeks later for completion ofendodontic retreatment, having remained free of anysymptoms. The sinus tract had resolved. After rubberdam isolation, the canal was irrigated with 1% sodiumhypochlorite to remove the calcium hydroxide dressingand dried with sterile paper points. The root canal wasfilled by lateral compaction of gutta-percha and AH-26sealer (DeTrey Dentsply, Konstanz, Germany), with the

root filling subsequently heated out to below the perfo-ration level with a System B (SybronEndo, Orange, CA,USA) heat source. Cavit was carefully removed fromthe perforation site using a DG16 endodontic explorer(Hu-Friedy, Chicago, IL, USA), and the perforationmargins re-cleaned with a small pulp bur. MTA (ProRootMTA, Dentsply Tulsa Dental) was mixed with sterilewater to a paste consistency, and carefully placed into theroot canal incrementally with a 5/7 endodontic handplugger (Dentsply Tulsa Dental) so as to seal the perfora-tion and re-create a smoothly tapered post space (Fig. 8).Direct observation of the perforation site through theoperating microscope was helpful to control correctplacement of the repair material and avoid inadvertentblockage of the post space. A moist cotton pellet was thenplaced in contact with the MTA to encourage setting andthe canal sealed with Cavit and Fuji IX.

The patient was recalled for construction of a cast post-core and crown. An acrylic crown was placed, with fab-rication of a metal-ceramic crown withheld until after asuitable observation period with evidence of healing. Toreduce the risk of vertical root fracture, the occlusion onthis tooth was constructed to provide light contact withprotection during excursive movements. Following treat-ment of tooth 21, a carious lesion on tooth 44 (Fig. 1) wasrestored, and tooth 34 extracted, prior to fabrication of anew mandibular removal partial denture in order toimprove posterior support. Tooth 42 was endodontically

Figure 6 Radiograph after temporary perforation repair with Cavit and

removal of the previous root filling.

Figure 7 Vacuum-formed removable prosthesis issued for use between

treatment visits.

Figure 8 Radiograph of tooth 21 immediately after root canal obturation

and definitive MTA perforation repair.




retreated, and was also found to have sustained a labialpost perforation. The patient declined to have the asymp-tomatic radiolucent lesion associated with tooth 12treated at this time.

At 1-year recall, the patient reported no symptoms.Tooth 21 was not tender to percussion and the labialmucosa related to the area was not tender to palpation.There was no sinus tract (Fig. 9), and probing depthswere within normal limits. The radiographs showedreduction in size of the lateral radiolucency (Fig. 10).Given the satisfactory outcome, the patient was advisedto have the acrylic crown replaced with a metal-ceramiccrown for improved durability. The patient will berecalled annually for long-term follow up.

Discussion

In endodontic practice, there are some cases whereconventional intraoral radiography does not provideadequate information on pathologic conditions andpositional relationships. With the recent introduction ofCBCT scanners for dental use, 3-D imaging has become apossibility. The 3D Accuitomo, known in some countriesas the 3DX Multi-Image Micro-CT, is of particular rel-evance to endodontics as it is specifically designed tocapture information from a small region of the maxillaor mandible. A high-resolution 3-D image of a column-shaped imaging area, 40 mm in diameter and 30 mm inheight, is produced, which is sufficient to analyse two tothree teeth in detail (17). The imaged area can be arbi-trarily sliced and observed from three different directions.CBCT technology is able to provide significantly higherresolution images than conventional medical CT at asmall fraction of the radiation dose (15,18). The dose perexposure to the 3D Accuitomo is similar to that frompanoramic radiography (15,17).

In this case, examination with the 3D Accuitomorevealed clear evidence of a post perforation through thelabial root surface of tooth 21. The presence and positionof the perforation and associated bone defect were con-firmed preoperatively, allowing the operator to be confi-dent in the diagnosis and treatment plan. In addition, thepatient found the CBCT images extremely helpful inunderstanding her endodontic problem. While CBCT hasbeen increasingly applied in treatment planning forperiapical surgery (19), as well as diagnosis of periapicallesions (20) and dento-alveolar trauma (21), this is thefirst reported use of this new technology for the diagnosisof lateral root perforation.

Three important factors relating to the potential tocontrol infection at the perforation site influence theprognosis for perforation repair procedures. These arethe time elapsed since creation of the perforation, thesize of the perforation, and the site of perforation inrelation to the level of crestal bone and epithelialattachment (1). The time factor relates to whether ornot the wound site has become infected, while largerdefects make it more difficult to create an effective sealand are associated with greater trauma to the adjacenttissues (22). Perforations occurring close to the ‘criticalcrestal zone’ may be complicated by periodontal break-down, with connection between the perforation defectand the oral cavity via a periodontal pocket (23). Oncea pocket has formed, management is problematicbecause persistent inflammation of the perforation sitewill be maintained by continuous ingress of bacteria viathe pocket. Such perforations have a poor prognosisfrom a periodontal standpoint, with endodontic treat-ment often unable to improve the condition (24). In thecase presented here, the perforation was located in themid-root region and there was no evidence of pocketingto the perforation site. As such, treatment of the defectwas deemed possible and dependent on control ofintraradicular infection.

Few clinical studies have drawn conclusions regardingthe influence of perforation on the outcome of endodon-tic treatment as this complication occurs infrequently.Most studies indicate that perforation will adversely affectprognosis (25–27); however, these studies were con-ducted prior to the introduction of the operating micro-scope and contemporary perforation repair materials.Farzaneh et al. found that the presence of a preoperativeperforation was the strongest predictor of a negativeoutcome following non-surgical retreatment: 42% ofteeth with perforation healed compared with 89%without (28). Importantly though, most perforations inthis study already had established infection and perfora-tions were repaired with resin-modified glass ionomercement.

Figure 9 Photograph 1 year after perforation repair, showing resolution

of the sinus tract.




Both MTA and SuperEBA have been recommended assuitable materials for repair of lateral root perforations(7,29). SuperEBA is a modified zinc-oxide eugenolcement that has been shown to produce a more effectiveperforation seal than either amalgam or glass ionomercement (29). While the tissue response to SuperEBA ismild (30), this material does not possess the same regen-erative properties as MTA (10). Main et al. reported on 16clinical cases in which perforations at various levels of theroot were repaired with MTA (2). Time from perforationto repair ranged from 12 to 45 months; seven of 16perforations had an associated radiolucency and nonewere associated with a periodontal pocket. All cases dem-onstrated complete healing after at least 1-year follow up.Comparison of the results of this study with the results ofreports on root perforations repaired with other materialsshows a marked improvement in the prognosis of teethrepaired with MTA. In the case reported here, healingwas achieved following MTA repair of a 15-year-old postperforation associated with a sinus tract and radiolucentlesion.

Conclusion

The presented case demonstrates that CBCT imagingtechnology is a useful addition to the endodontist’sarmamentarium for the diagnosis and management ofcomplex endodontic problems. Root perforation in themiddle third of a maxillary central incisor occurring15 years previously was treated with a non-surgicalapproach using MTA with the aid of an operating micro-scope. The repaired tooth demonstrated resolution of a

sinus tract, absence of symptoms and radiographichealing at 1-year recall.

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Young AEJ2007