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J Oral Maxillofac Surg68:2385-2390, 2010

Is Endodontic Treatment NecessaryDuring Coronectomy Procedure?

Metin Sencimen, DDS, PhD,* Kerim Ortakoglu, DDS, PhD,†

Cumhur Aydın, DDS, PhD,‡ Yavuz S. Aydintug, DDS, PhD,§

Aykut Ozyigit, DDS, PhD,� Tuncer Ozen, DDS, PhD,¶ and

Yilmaz Gunaydin, DDS, PhD#

Purpose: Close proximity of the inferior alveolar nerve (IAN) to the third molar roots can result innerve injuries during extraction of third molars. Consequently, it is necessary to determine the relation-ship of the nerve and roots to avoid damage to the IAN. Computed tomography scans are widely usedto determine the correct relationship between the IAN and lower third molars.

Patients and Methods: The study consisted of 10 patients with 16 lower third molars in closerelationship with the IAN who were divided into a study group and a control group. The patients in thestudy group were treated via coronectomies performed with endodontic treatments. The patients in thecontrol group underwent coronectomies without endodontic treatment. The patients were followed upfor at least 1 year.

Results: We had to extract 7 of the roots because of the infection in 8 patients belonging to the studygroup, which were treated endodontically. Moreover, there were 3 cases of IAN damage because of theextraction in the study group. However, in the control group, no infection was determined and IANdamage was absent.

Conclusion: Coronectomy appears to be a reliable technique to protect the IAN from damage. Thisprocedure has a low incidence of complications. Endodontic treatment does not affect the success of thismethod according to our results.© 2010 American Association of Oral and Maxillofacial Surgeons

J Oral Maxillofac Surg 68:2385-2390, 2010

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nferior alveolar nerve (IAN) injury encountered duringurgical operations can result in various levels of com-lications1 that mostly occur during impacted mandib-lar third molar removals.1-5 Mandibular posterior

mplant placements, bone graft harvesting, and orthog-athic surgeries are other operations that can give rise toAN damage.6,7 The reason for this complication during

eceived from Gülhane Military Medical Academy, Ankara, Turkey.

*Associate Professor, Department of Oral and Maxillofacial Surgery.

†Associate Professor, Department of Oral and Maxillofacial Surgery.

‡Associate Professor, Department of Endodontics.

§Professor, Department of Oral and Maxillofacial Surgery.

�Specialist, Department of Oral and Maxillofacial Surgery.

¶Professor, Department of Oral Diagnosis and Radiology.

#Professor, Department of Oral and Maxillofacial Surgery.

Address correspondence and reprint requests to Dr Sencimen:

epartment of Oral and Maxillofacial Surgery, Gülhane Military

edical Academy, GATA Dishekimligi Bilimleri Merkezi, Etlik, An-

ara, Turkey; e-mail: metinsencimen@yahoo.com

2010 American Association of Oral and Maxillofacial Surgeons

278-2391/10/6810-0004$36.00/0

oi:10.1016/j.joms.2010.02.024

2385

mpacted third molar removal is thought to be the closeelationship of the root tips with the IAN.1-12 This closeroximity may lead to temporary or permanent pares-hesia after the tooth removal. Permanent paresthesiasre generally induced by the deterioration of nerve in-egrity or degeneration under compressive stresses as aesult of excessive trauma. This condition usually occursn cases where the IAN is placed between the roots,

hich are fused at the tips.2,3,5 When the radiologicarkers of proximity of the IAN to the root of the thirdolars are present, the possibility of damage can be asigh as 35%.2

There are several articles in the literature indicatinghat the relationship between the IAN and the man-ibular third molar could be determined by conven-ional periapical and panoramic radiographs. Accord-ng to those articles, there are 3 radiographic featureseeded to make a decision regarding whether there isclose relationship. These are as follows:

1. Alteration in the trace of the mandibular canal.2. Radiolucency over the image of the root tips.3. Interruption of the continuity of the lamina dura

over the wall of the mandibular canal.3,4,6,8-10,12

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2386 ENDODONTIC TREATMENT DURING CORONECTOMY

Although it is known that the proximity of the IANnd mandibular third molars can be detected by con-entional imaging techniques, it can sometimes bempossible to determine in the absence of computedomography (CT) scanning images.13 The disadvan-age of CT is the relatively high radiation dose andost. However, the high radiation factor can be elim-nated with the use of cone-beam CT technology,

hich is currently available in a dental practice.14-16

To avoid the possibility of the IAN injury duringhird molar removal, coronectomy can be performed.oronectomy is the removal of the crown of a toothith the root being left in place.1-4 In the literature

he coronectomy technique has been widely used torotect the IAN from injuries occurring as a result of

mpacted mandibular third molar removals. Therown and one third of the coronal section of theoots are removed,2-5 and no procedure is performedn the section that is in close relation to the IAN.herefore IAN damage is out of consideration.The most common indication for impacted thirdolar removal is eruption difficulties leading to peri-

oronitis by the aid of coronectomy; the crown caus-ng the pericoronitis and the dental follicle, which arehe chief reasons for inflammation, are removed.herefore the problem is resolved.1-3 In the literature

he discussion on this subject is focused on the infectionr a similar complication caused by the root that was

eft and especially the partially resected pulp tis-ue.17,18

The aim of this study is to determine the efficacy ofhe endodontic treatment with the coronectomy pro-edure and to discuss the necessity for endodonticreatment during coronectomies.

atients and Methods

The study was performed on 16 impacted mandib-lar third molar teeth in 10 patients (4 male patientsith a mean age of 23 years and 6 female patientsith a mean age of 19 years) who were referred to theepartment of Oral Diagnosis and Radiology and De-artment of Oral and Maxillofacial Surgery, Gülhaneilitary Medical Academy, between the years of 2004

nd 2005 (Table 1). All patients were thoroughlynformed about the procedure and signed a writtenonsent form. In addition, local ethics approval was

Table 1. NUMBERS AND MEAN AGES OF PATIENTS

No. of Patients Mean Age (yr)

emale 6 19ale 4 23

mencimen et al. Endodontic Treatment During Coronectomy.Oral Maxillofac Surg 2010.

btained for the main study (GMMA 68/373; June 30,006).The inclusion criteria was the high risk of injury to

he IAN based on panoramic radiographs. The rela-ionship between the impacted tooth roots and theAN is detected by panoramic radiographs and evalu-ted with respect to the criteria of Howe and Poyton.8

here the panoramic images were insufficient toescribe the contact between the roots and the IAN,he spiral tomographic cross-sectional slices weresed to determine the exact relationship (Fig 1). Theatients enrolled in the study met the following in-lusion criteria: 1) cooperation with the study andostoperative follow-up and 2) absence of uncon-rolled medical conditions such as diabetes mellitus,mmune compromise, head and neck radiotherapy,alcium imbalance, and so on. Exclusion criteria were) the presence of active infection or tooth mobility;) uncontrolled systemic diseases (diabetes mellitus,

mmune compromise, head and neck radiotherapy,alcium imbalance, and so on); 3) radiation to theead and neck; and 4) local pathologic conditionselated to the roots of the impacted molars. Further-

IGURE 1. A, The relationship between the impacted lower thirdolar tooth roots and the IAN is detected on panoramic radio-raphs. B, Spiral tomographic cross-sectional slices verified theelationship between the same patient’s IAN and lower third molaroots.

encimen et al. Endodontic Treatment During Coronectomy.Oral Maxillofac Surg 2010.

ore, angulations of third molars were disregarded.

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The study consisted of 10 patients with 16 lowerhird molars in close relation with the IAN who un-erwent coronectomies and were divided into a studyroup and a control group. Eight teeth in 5 patients inhe study group were treated by coronectomies per-ormed with root canal treatment. Eight teeth in 5atients in the control group underwent coronecto-ies without endodontic treatment (Table 2). The

perations were performed with patients under localnesthesia. None of the cases were prescribed preop-rative prophylactic antibiotics; however, they wererescribed postoperative anti-biotherapy as a measuref surgical wound infection. The patients used a po-idone-iodine mouthwash before surgery. Coronec-omy was performed by use of the buccal approach inll cases. All coronectomies were performed by theame surgeon. In addition, all endodontic treatmentsere performed by the same endodontist.In the study group, pulpectomy and biomechanical

reparation were performed (Fig 2). The root canalsere irrigated with a saturated solution of calciumydroxide with the purpose of making the dentinlkaline. Thereafter the canals of the third molarsere filled with the aid of a Lentulo spiral (Dentsply,etropolis, Brazil). Finally, mineral trioxide aggregateMTA) cement (Anglinos, Londrina, Brazil) was used

Table 2. TREATMENT PROTOCOLS ACCORDING TO GEN

CoronectomyCorone

Can

emale (n � 6) 4 (n � 2)ale (n � 4) 4 (n � 2)otal (N � 10) 8 (n � 4)

encimen et al. Endodontic Treatment During Coronectomy. J O

IGURE 2. DEMO device for biomechanical preparationMaillefer Dentsply, X-Smart, Ballaigues, Switzerland).

encimen et al. Endodontic Treatment During Coronectomy.Oral Maxillofac Surg 2010.

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s a canal-filling material. The endodontic procedureas performed under aseptic conditions in the oper-

ting room.The buccal approach was preferred for access in all

ases, and the crown including the dental follicle wasemoved with one third of the root coronally. Inractice, while separating the crown from the root, alope is formed, the level of which decreases fromuccal to lingual (Fig 3). This inclination causes aharp edge form of the root at the buccal alveolarrest level while leaving 3 to 4 mm of the root downelow the lingual alveolar crest level. To overcomehis situation, after the separation of the crown, theuccal root surface was reduced to the lingual root

evel by the help of a carbide rose-head bur. Afterrrigation of the surgical area with copious salineolution, the wound edges were closed primarily. Inhe study group, after removal of the pulp and bio-echanical preparation, the canals were filled withTA (Fig 4). To prevent over- or underfilling of the

anals, control periapical radiographs were taken pe-iodically. All the root canals in the study group weredequately filled to the apices. Brand new sharp bursere used for every operation so as to excise the

rown without mobilizing the roots. In the controlroup the pulp was left in place (Fig 5).

Plus Rootatment Single Side Left and Right

4) 4 (n � 4) 2 (n � 2)2) — 4 (n � 4)6) 4 (n � 4) 12 (n � 6)

xillofac Surg 2010.

FIGURE 3. Technique for removal of lower third molar.

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2388 ENDODONTIC TREATMENT DURING CORONECTOMY

At the end of the first, third, and sixth months ofhe postoperative follow-up period, control panoramicadiographs were taken (Fig 6). Finally, 1 year afterhe operation, the last panoramic radiographs wereaken for assessment of the coronectomy sites.

esults

The results of both groups are shown in Table 3. Inhe study group, 7 roots of the third molars had to beemoved because of infection after the procedure.nfections appeared right after the coronectomy andoot canal treatment. However, in the control group,nly 1 root had to be removed because of opening ofhe surface. This open wound caused an infectionuring the healing period. In addition, 3 patients inhe study group with the need for extraction hademporary loss of sensation on their IANs after extrac-ion.

In the control group, we surprisingly determinedhat the roots had moved into the coronal direction at

IGURE 4. A, Removal of pulp and biomechanical preparation ofoots. B, Filling of canals with mineral trioxide aggregate.

encimen et al. Endodontic Treatment During Coronectomy.Oral Maxillofac Surg 2010.

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month after the procedure. In this way the closeelationship between the roots and IAN had disap-eared (Fig 7).

iscussion

Damage to the IAN can occur during routine ex-raction of impacted lower third molars.8,11,19 Neuralomplications in these situations are observed mostlyhen the apices of the wisdom teeth and IAN are in

lose anatomic proximity.1-5 Even though panoramic

FIGURE 5. The pulp was left in place in the control group.

encimen et al. Endodontic Treatment During Coronectomy.Oral Maxillofac Surg 2010.

IGURE 6. A, Panoramic radiograph taken 6 months after coro-ectomy. B, Panoramic radiograph taken 6 months after coronec-omy plus root canal treatment.

encimen et al. Endodontic Treatment During Coronectomy.Oral Maxillofac Surg 2010.

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SENCIMEN ET AL 2389

adiographs are able to show the properties of thategion,3,6,8,10,12 detailed observation of this relation-hip is possible only on cross-sectional spiral CTcans.4,20-22 The disadvantage of CT is exposure to areater amount of radiation in patients; however, newone-beam CT scanners offer reduced exposure timesith minimal radiation.14-16 In our study, we did notenefit from the CT scans directly in all cases. CTcans were used only in cases in which difficulty wasssessed with orthopantomography.

Ecuyer and Debien23 were the first to describe theoronectomy procedure, and after much research,his technique is considered very useful to preventny damage to the IAN during removal of impactedeeth adjacent to the inferior alveolar bundle.1-5 Theemaining pulp in the apex of a root, which wasubjected to necrosis over time after coronectomy,as the main target for serious discussions in the pastecause the necrotic pulp was considered the triggeror apical periodontitis or orofacial infections.17,24

ecause of the present dilemma and existing suspi-ions about the latter, we studied the efficacy ofemoving pulpal tissue and remnants during coronec-omy and assessed its contribution to the issue.

In this study the coronectomies were performedccording to Pogrel et al1 and the root fillings madeith MTA. Neither pathology nor infection was en-

ountered in the control group during the follow-uperiod; however, secondary surgery was performedo extract the remaining teeth in the study group withTA root fillings, where 7 of 8 teeth were infectedostoperatively. Complications observed after extrac-ions of impacted third molar teeth were estimated toccur in direct relation with the duration of surgery.25

rolongation of surgical time was considered to in-rease risk of infection. In our study, a similar resultas obtained because application of MTA root canallling caused considerable prolongation of the surgi-al time. The higher incidence of postoperative infec-ion of that group could be related to this phenome-on. It is known that MTA is an effective preparationor apexification and root canal–filling material.26 Be-ause of this, we preferred to use MTA in our study.herefore we decided that the abundance of postop-

Table 3. RESULTS

Complications No Complications

oronectomy 1 7oronectomy plus rootcanal treatment 7 1

otal 8 8

encimen et al. Endodontic Treatment During Coronectomy.Oral Maxillofac Surg 2010.

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nd root canal–filling material were applied did notriginate from the features of the root canal–fillingaterial.In the control group, only 1 tooth had to be ex-

racted because of postoperative infection after coro-ectomy, but that complication occurred almost 1ear later, and the remaining root moved in the coro-al direction by exposure through the mucosa. Wehink that the lack of successful primary wound clo-ure was responsible for this complication.

In the control group, the teeth remained vital, be-ause the pulp was left vital in the apices. However,xtra channel treatment adds invasiveness to theoronectomy procedure. The pulp is extirpated andhannels instrumented to some extent, which is re-ponsible for extra mobility of the roots. This wasonfirmed in our study during the second surgeries,uring which mobility was assessed in all extractedeeth. On the other hand, animal studies have shownhat vital roots remain vital with minimal degenerativehanges. Osteocementum usually extends to coverhe roots.27-29

Morphology of the roots is another factor contrib-ting to successful coronectomy. Small and conicaloots are prone to easier mobilization, and this coulde the reason for the occurrence of apical infection.enton et al3 reported postoperative failure in 36ases among 94 coronectomy patients. They corre-ated failure to the inappropriate morphology of themall and conical roots. We preferred to extract theeeth with similar morphology in our study instead ofrying to perform coronectomy. Nerve damage occur-ing after extraction of such teeth was considered toe transient; in addition, such a neural complicationould heal more quickly. Renton et al pointed out theise in apical infection in the remaining roots after 2ears of follow-up. We did not find any problems afterhe second postoperative year in all cases treated byoronectomy, and our follow-up continues.In this study we observed coronal movement of the

esected roots in accordance with most of the previ-us studies.1,3,4 In the control group, a root causing

IGURE 7. A, Panoramic radiograph taken immediately afteroronectomy procedure. B, Panoramic view in same patient takenyears after procedure, showing eruption of impacted roots.

encimen et al. Endodontic Treatment During Coronectomy.Oral Maxillofac Surg 2010.

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2390 ENDODONTIC TREATMENT DURING CORONECTOMY

nfection was extracted and the IAN was protected inhat way. The same eruption could not be observed inhe study group because of initiation of infection inhe early period. One root in the study group did notrupt; however, eruption occurred in the controlroup because vitality might be responsible for suchoot movement.

On the basis of the findings from this study, weonclude that coronectomy is a safe and reliableethod of avoiding injury to the IAN when removing

ppropriate third molars. In addition, carrying outntraoperative root canal therapy does not add any-hing to the procedure, considerably increases theomplication and infection rates, and is therefore notecommended. Furthermore, movement of the resid-al roots does occur, but the direction of movement

s away from the nerve when they are supposed toomplicate IAN, and thus it is possible to extract teethithout any neural complications during the some-

imes problematic postoperative period.

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