Clinical Research

A Prospective Study of the Extraction and RetentionIncidence of Endodontically Treated Teeth with UncertainPrognosis after Endodontic ReferralNestoras E. Tzimpoulas, DDS, Michalis G. Alisafis, DDS, MSc, Giorgos N. Tzanetakis, DDS, MSc,and Evangelos G. Kontakiotis, DDS, PhD

Abstract

Introduction: The present study was conducted withthe aim to assess the extraction and retention incidenceof endodontically treated teeth with an uncertain prog-nosis after endodontic referral and to evaluate thefactors related to the decision-making process.Methods: Two hundred seventy-five permanent teethwere clinically and radiographically evaluated by 3 expe-rienced endodontists. The type of tooth, age and sex ofthe patients, the motive of referral, and the main chiefcomplaint were the initial recorded data. The associa-tions between extraction reasons and the patients’age and sex or tooth type were analyzed using thechi-square test. Results: Of the 275 teeth examined,217 (79%) were finally extracted. The remaining 58(21%) teeth were endodontically retreated and restored.A questionable clinical status was the main motive forendodontic referral (57.1%). The teeth most extractedwere maxillary molars (36.2%) followed by mandibularmolars (32.9%). The most prevalent reason for extrac-tion was nonrestorable caries (37.1%). The majority ofthe teeth retained in the oral cavity needed surgical peri-odontal or endodontic management. Conclusions: Themost frequent reason responsible for the fate ofendodontically treated teeth is the pronounced loss ofdental tissues. Endodontic referral may aid in thesurvival of some carefully selected cases of endodonti-cally treated teeth. (J Endod 2012;38:1326–1329)

Key WordsEndodontically treated teeth, extraction, rationale,retention

From the Department of Endodontics, Dental School,University of Athens, Athens, Greece.

Address requests for reprints to Dr Evangelos G. Kontakio-tis, 2 Antheon Str, Patisia, 11143 Athens, Greece. E-mailaddress: ekontak@dent.uoa.gr0099-2399/$ - see front matter

Copyright ª 2012 American Association of Endodontists.http://dx.doi.org/10.1016/j.joen.2012.06.032

1326 Tzimpoulas et al.

The prevention and treatment of apical periodontitis is the main long-term purpose ofroot canal therapy (1). The optimal results of endodontic treatment are the healing

of periradicular tissues and the achievement of functionality of the treated teeth (1, 2).The progress and continuous development of endodontic operative techniques havesignificantly contributed to those purposes offering a lot of benefits to the cliniciantrying to achieve an appropriate treatment outcome (3–5).

Nevertheless, in everyday clinical practice, clinicians may decide to extract anendodontically treated tooth for a number of reasons. Extraction still retains its validityas a treatment option despite our improved knowledge about the biological and clinicalfactors that determine the prognosis of an endodontically treated tooth and the advance-ment of novel endodontic techniques and materials (6–8).

Despite the fact that many clinical studies have been performed dealing with thesuccess and failure of endodontic treatment, only a few have focused on the reasonsthat might cause the loss of endodontically treated teeth (9–12). The majority ofthese studies have retrospectively found that the major issue regarding the retentionof endodontically treated teeth was the questionable or poor expected restorativeoutcome. Periodontal disease and endodontic treatment failure were the other 2most prevalent reasons for extraction, whereas a significant proportion of teeth wereextracted because of the presence of a vertical root fracture (9–13).

A recent prospective study has analyzed this issue with a different and moredetailed approach, but the results were based on questionnaires answered by generaldentists (12). It is also noteworthy that none of these studies has taken into consider-ation patients’ wishes as an additional option for the decision-making process. Financialissues and patients’ related factors (ie, preference and autonomy) appear to be the 2main reasons that sometimes lead patients to decide to have teeth extracted rather thanundergoing endodontic retreatment or periradicular surgery. Moreover, in a study likethis, it is very important to collect data from endodontists in order to obtain moreprecise information about the clinical and radiographic status of the teeth and alsoto secure that all treatment options were exhausted before tooth extraction. The aimof the present study was prospectively 2-fold: first, to evaluate the extraction incidenceof endodontically treated teeth with an uncertain prognosis after endodontic referraland second to define all the related factors affecting the decision for extraction andretention of the same teeth.

Materials and MethodsData were gathered from 275 endodontically treated permanent teeth of 270

patients referred to 3 different endodontic offices for clinical and radiographic evalu-ation regarding the possibility of teeth retention. The study took place from September5, 2010, to July 29, 2011. For each patient, a special file was completed in order toobtain the required information. Among the data collected were patients’ sex andage, the main reason of referral, the type of the tooth, and the main chief complaint.

Each tooth was clinically and radiographically evaluated by 3 examiners(endodontists) who had been previously calibrated mainly for the determination ofthe clinical status of the teeth. The radiographic evaluation initially took place indepen-dently based on the clinical experience of each examiner. Only 1 diagnosis could be

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Figure 1. Distribution of the extracted teeth according to tooth type.

Clinical Research

noted for each examination. If more than 1 factor was documentedrelated to tooth extraction, the more untreatable condition was chosen(eg, vertical root fracture over iatrogenic perforation). Disagreementsand different opinions were discussed among the examiners a secondtime until a consensus was reached. The decision for teeth extractionor retention was made after clinical and radiographic evaluations anda consensus was reached among the 3 examiners regarding the radio-graphic appearance of the teeth. In the majority of the cases, the clinicalevaluation included the isolation of the teeth with a rubber dam, cariesremoval, access of the pulp chamber, and microscopic examination. Anadditional parameter (patients’ wishes) was taken into accountregarding the treatment options (ie, conventional or surgical manage-ment or extraction) of the examined teeth.

Clinical conditions related to the extraction of endodonticallytreated teeth were classified in 12 different categories (ie, vertical rootfracture, calcification plus patients’ wishes, cervical resorption pluspatients’ wishes, dental trauma, endoperiodontal lesion, endodonticfailure plus patients’ wishes, iatrogenic perforation, nonrestorablecaries, orthodontic reasons, periodontal disease, prosthetic reasons,and an unrestorable cusp fracture). Additionally, teeth planned forextraction were classified into 8 different categories according to thetype of tooth (ie, maxillary incisor, mandibular incisor, maxillary canine,mandibular canine, maxillary premolar, mandibular premolar, maxillarymolar, and mandibular molar).

Data were pooled and statistically evaluated by SAS version 9.0(SAS, Cary, NC). Ninety-five percent confidence intervals (CIs) werecalculated with the aim to estimate differences between proportions.The associations between extraction reasons (ie, nonrestorable caries,vertical root fracture, periodontal disease, perforation, and so on) andpatients’ age and sex or tooth type (eg, maxillary vs mandibular molarsand so on) were analyzed using the Pearson chi-square test. The level ofstatistical significance was set at 95% (P < .05).

ResultsOf the 275 endodontically treated teeth examined, 217 (79%)

were extracted. The remaining 58 (21%) teeth were endodontically re-treated, permanently restored, and programmed for recall examinationevery 6 months for at least 2 years. A questionable clinical status of teethwas the mainmotive for endodontic referral (57.1%) followed by a highsuspicion of the presence of a vertical root fracture (13.8%), iatrogenicperforation (10.9%), endodontic failure (9%), an endoperiodontallesion (4%), and calcification (2.9%). The remaining 2.2% includedother reasons for referral such as dental trauma, periodontal disease,and cervical resorption (Table 1).

The distribution of the extracted teeth is shown in Figure 1. Themost commonly extracted teeth were maxillary molars (36.2%) andmandibular molars (32.9%). Other categories of teeth followed withlower percentages such as maxillary premolars (12.7%), mandibularpremolars (11.3%), maxillary incisors (2.8%), mandibular incisors(2.8%), mandibular canines (0.9%), and maxillary canines (0.5%).

TABLE 1. Distribution of the Teeth According to the Main Motive forEndodontic Referral

Main motive (N = 275) n %

Questionable clinical status 157 57.1Possible presence of a vertical root fracture 38 13.8Iatrogenic perforation 30 10.9Endodontic failure 25 9Endoperiodontal lesion 11 4Extensive calcification 8 2.9Other 6 2.2

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The reasons for extraction of the teeth examined are diagrammat-ically presented in Figure 2. Nonrestorable caries was the most preva-lent reason (37.1%; 95% CI, 30.6%–43.6%). Other significant reasonswere nonrestorable cusp fracture (17.8%; 95% CI, 12.7%–23%) andthe presence of a vertical root fracture (10.3%; 95 CI, 6.2%–14.4%).Other reasons were periodontal disease (8.5%), iatrogenic perforation(6.6%) or the initial presence of a perforation (0.5%), endodonticfailure (5.6%), a prosthetic reason (4.2%), an endoperiodontal lesion(2.8%), dental trauma (2.3%), orthodontic reasons (1.9%), calcifica-tion (1.4%), and cervical resorption (0.9%).

No significant differences were found among the different groupages (P = .679) and sex (P = .422) regarding the prevalence of theclinical condition of ‘‘nonrestorable caries.’’ Nonrestorable carieswere significantly more prevalent in molars than in premolars (P <.001) but without differences between mandibular and maxillarymolars. The tendency for a decrease of the clinical condition of ‘‘unrest-orable cusp fracture’’ as patients’ ages increased (P = .063) was alsoevident.

Of the 58 teeth retained, 28 needed a surgically crown-lengtheningprocedure. All these teeth were endodontically retreated and restoredusing either a cast or a prefabricated post. Fifteen teeth were onlyconventionally retreated and permanently restored with a single crown.Ten teeth were surgically retreated using a microscope and mineraltrioxide aggregate (MTA) as retrofilling material. MTA was also usedas a repair perforation material in the remaining 5 teeth.

DiscussionThe present study was conducted with the aim to investigate more

precisely the reasons that determine the decision-making processregarding the retention or extraction of endodontically treated teethwith an uncertain prognosis. This was performed in 2 different ways.First, the procedure was completed using a prospective approach inorder to minimize the risks and limitations as a result of the interpre-tation of retrospective data. Second, the clinical and radiographic eval-uations of the teeth were performed by 3 experienced endodontists afterpatient referral to their private clinic. However, the calibration of clin-ical examiners remains a major difficulty and is a common limitation inthese types of studies (14). Another serious limitation is also that a greatnumber of endodontically treated teeth are probably extracted bygeneral dentists for various reasons without previous referral toendodontists. All these teeth are automatically excluded from a studylike this without the appropriate analysis of the extraction reasons.

The main motive for endodontic referral of endodontically treatedteeth with an uncertain prognosis was found to be their questionableclinical status. In the majority of cases, caries of the pulp chamber floorwere evident during clinical microscopic examination. This finding wasconsidered to be crucial in the decision of retention of the tooth in the

n and Retention of Endodontically Treated Teeth with Uncertain Prognosis 1327

Figure 2. A diagrammatic presentation of the extraction reasons of the endodontically treated teeth examined.

Clinical Research

oral cavity. The second most frequent reason was the possible presenceof vertical root fracture. In all cases in which a vertical fracture wasfinally diagnosed, a localized deep periodontal pocket was detectedalong the fracture line.

Maxillary molars were found to be the most commonly extractedteeth followed by mandibular molars, however, without statisticallysignificant differences. This finding is in contrast with the results ofprevious similar studies that have noted a significant predominanceof extraction for endodontically treated mandibular molars (11, 12).Despite these minor differences among the studies performed, it isvery important to notice the great tendency of molars to fracture,especially in cases in which an adequate prosthetic restoration isabsent. This observation has also been bibliographically documentedby previous similar studies showing the significance of full-crowncoverage for the survival of endodontically treated teeth (15–18).

Under the conditions of the present study, it was also shown thatthe key factor in the decision to extract or retain endodontically treatedteeth is the pronounced loss of dental tissues. This result is in contrastwith the findings of a recent prospective study that was based on a ques-tionnaire survey answered by general dentists (12). This study by Tour�eet al (12) concluded that themain reason for the extraction of endodon-tically treated teeth by general dentists is severe periodontal disease fol-lowed by endodontic failure and vertical root fracture. Thesecontradictory findings show the subjectivity that characterizes thismatter as well as the major dilemma that general dentists encounterwhen they have to decide about restorative issues of endodonticallytreated teeth. Another serious reason that possibly explains this findingis, as previously stated, that a number of endodontically treated teeth areextracted without previous referral to endodontists including severelyperiodontally involved teeth with a high degree of mobility.

Vertical root fractures steadily possess a high rate among theextraction reasons of endodontically treated teeth as revealed by theliterature (19). The present study showed that almost 1 out of 10endodontically treated teeth with a questionable prognosis is extractedbecause of the presence of a vertical root fracture. This result is intotal agreement with the results of the majority of previous similarstudies whose respective percentages range between 8.8% and13.4% (9–12). Only Sjogren et al (13) reported a significantly higherincidence (31%) of vertical root fractures among endodonticallytreated teeth (13).

It is also of great interest that a small number of teeth were onlyextracted because of endodontic treatment failure. This finding is in

1328 Tzimpoulas et al.

total agreement with the respective data provided by some importantand relevant large epidemiologic studies (18, 20, 21). In the presentstudy, endodontic failure was definitely diagnosed as post-treatmentapical periodontitis. Sinus tracts and clinical symptoms (spontaneouspain or pain to percussion) were also present in the majority of thecases. The quality of endodontic treatment and the coronal restorationplayed an important role concerning the treatment options proposed tothe patients. If the endodontic treatment was evaluated as insufficient,the first option was conventional retreatment. If the treatment was eval-uated as sufficient or a cast post was present, then the first option wasperiapical surgery. In the present study, all these teeth were finally ex-tracted because patients did not consent to any further treatment such asconventional retreatment or periradicular surgery. The patients’ wishesalso played an important role in the decision-making process in teethwith extensive calcification and cervical resorption. This parameter ispresented as an additional factor for the first time confirming howimportant patients’ consensus is during the treatment decision processand also the respect of the concept of ‘‘patient autonomy’’ (22, 23).

Additionally, it should be noted that patients’ wishes have only beenincluded in 3 of the 12 classifications. This is because it was initiallyconsidered that patients’ wishes could not play any role in verticalroot fractures, in severely periodontally involved teeth (ie, a severe en-doperiodontal lesion or periodontal disease), in large iatrogenic perfo-rations, or when unrestorability is diagnosed (ie, nonrestorable cariesand unrestorable cusp fracture). Dental trauma was also important in5 cases of severe horizontal midroot fractures in which the treatmentdecision was extraction and implant placement. Orthodontic and pros-thetic reasons represented 13 cases of endodontically treated teeth (4and 9, respectively) in which endodontic failure occurred. Endodonticretreatment or endodontic surgery was feasible, but the orthodontistand prosthodontist did not wish to take a risk using these teeth in theirtreatment planning, so the extraction was necessary independently ofpatients’ wishes.

Finally, the majority of the retained teeth needed surgical manage-ment of both soft and hard dental tissues. This fact shows the usefulnessof microsurgical endodontic and periodontal techniques toward theaim of survival of endodontically treated teeth with an uncertain prog-nosis. MTA was also the material of choice for all surgical endodontictechniques. The further improvement of the already existing techniquesand the development of novel techniques andmaterials will certainly aidin the efforts regarding the survival of more and more endodonticallytreated teeth with a questionable or uncertain prognosis.

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Clinical Research

AcknowledgmentsThe authors deny any conflicts of interest related to this study.

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