Clinical Research

The Dynamics of Periapical Lesions in EndodonticallyTreated Teeth That Are Left without Intervention:A Longitudinal StudyIgor Tsesis, DMD,* Tomer Goldberger, DMD,* Silvio Taschieri, MD, DDS,

†Mottie Seifan, DMD,

‡

Aviad Tamse, DMD,* and Eyal Rosen, DMD*

Abstract

Introduction: The long-term dynamics of periapicallesions in endodontically treated teeth is not fully eluci-dated, thus presenting a clinical dilemma regarding theneed for an intervention. The aim of the studywas to retro-spectively evaluate the long-term dynamics of periapicallesions that were left without intervention in endodonti-cally treated teeth. Methods: Periapical status surveysof patients treated in a public dental clinic were retrospec-tively evaluated for the presence of periapical lesions inendodontically treated coronally restored teeth. Thedynamics of the included periapical lesions was evaluatedbased on the periapical index (PAI) score changes between2 consecutiveperiapical surveys of at least a4-year interval.The influence of various factors on lesion dynamics wasstatistically evaluated. Results: The study cohort consistedof 74 patients with a total of 200 endodontically treatedteeth having periapical lesions that fulfilled the inclusioncriteria. Fifty-seven (28.5%) lesions remained unchanged,103 (51.5%) lesions worsened (PAI score increased), and40 (20%) lesions improved (PAI score decreased). Poorroot canal filling and poor restoration were found toadversely affect the long-term dynamics of the periapicallesions (P < .05). Age, sex, and the presence of a posthad no statistically significant influence on lesion dynamics(P > .05). Conclusions: Poor root canal filling and poorrestoration may adversely affect the long-term dynamicsof periapical lesions that are left without intervention inendodontically treated teeth. Therefore, in cases of poorroot canal filling or poor restoration, further interventionmay be indicated. (J Endod 2013;39:1510–1515)

Key WordsEndodontically treated teeth, periapical lesion, persis-tent apical periodontits

From the *Department of Endodontology, Maurice and Ga-briela Goldschleger School of Dental Medicine, Tel Aviv Univer-sity, Tel Aviv, Israel; †Center for Research in Oral Health,Department of Biomedical, Surgical, and Dental Sciences, Uni-versit�a degli Studi di Milano, IRCCS Istituto, Ortopedico Ga-leazzi, Milan, Italy; and ‡MaccabiDent, Tel Aviv, Israel.

Address requests for reprints to Dr Igor Tsesis, Departmentof Endodontology, Tel Aviv University Dental School, RamatGan, Israel. E-mail address: dr.tsesis@gmail.com0099-2399/$ - see front matter

Copyright ª 2013 American Association of Endodontists.http://dx.doi.org/10.1016/j.joen.2013.09.010

1510 Tsesis et al.

The main goal of endodontic treatment is either to prevent or to treat periapical pa-thology (1). However, a relatively high prevalence of persistent apical periodontitis

(AP) in endodontically treated teeth, ranging from 40%–61%, has been identified incross-sectional studies (2–4). The main reason for the persistence of AP afterendodontic treatment is bacteria remaining in the root canal system or penetratingthe root canal system as a result of coronal leakage (5–10). Additional possibleetiologies include the presence of true cysts, extraradicular infection, or foreignbody reactions (11–14).

The treatment alternatives for persistent AP include nonsurgical endodontic re-treatment, surgical endodontic treatment, or tooth extraction (15, 16). Anotheralternative for certain cases is to leave the tooth without intervention and adopt along-term follow-up protocol (17). What may be the consequences of treating or nottreating an existing pathology is a crucial question, which constitutes the core of theclinical decision-making process (18). However, the long-term dynamics of periapicallesions in endodontically treated teeth and possible influencing factors are not fullyelucidated, thus presenting a real clinical dilemma regarding the need for an interven-tion. The aim of this study was to retrospectively evaluate the long-term dynamics ofperiapical lesions that were left without intervention in endodontically treated coronallyrestored teeth and the effects of possible influencing factors.

Materials and MethodsAll records of patients treated in a public dental clinic between 2007 and 2009

were retrospectively collected. Approval for the project was obtained from the institu-tional review board. Only records with 2 consecutive full periapical status surveys withan interval of at least 4 years were further evaluated. The teeth included in the study wereteeth with root canal treatment (RCT) and coronal restoration that had been completedat least 1 year before the first survey and with a periapical lesion present at the firstsurvey. Only teeth that were presented in the periapical status surveys in at least 2 peri-apical x-rays with different angulations were included.

Teeth excluded from the study were teeth that were extracted, endodonticallyretreated, or with coronal restoration replaced before the second survey. Teeth witha radiographic lesion not located in the periapical area and/or with a discernibleroot perforation (19) or a vertical root fracture (20) were also excluded.

All relevant radiographs were digitized into JPEG format using Nikon CoolPics 950digital camera (Nikon, Tokyo, Japan) at a resolution of 1600� 1200 pixels; brightnessand contrast were automatically adjusted for all images using Adobe Photoshop 7.0 soft-ware (Adobe, San Jose, CA), and the images were then evaluated in a dark room using a15-inch computer screen and a 1280� 800 pixel resolution. Images of the initial peri-apical status surveys were evaluated for relevancy based on the inclusion and exclusioncriteria separately by 2 observers (T.G. and I.T.). Later, only for the included cases, theconsecutive periapical status surveys were evaluated separately by the 2 observers (T.G.and I.T.). In cases of disagreement, the images were evaluated jointly by the observersuntil an agreement was achieved.

The periapical status of the involved teeth was evaluated during the inclusionprocess and at each time point using the periapical index (PAI) score (21). A set of

JOE — Volume 39, Number 12, December 2013

TABLE 1. Distribution of the Initial and Final Periapical Index (PAI) Scores(median = 6-year interval)

PAIscore

No. of teeth oninitial observation (%)

No. of teeth onfinal observation (%)

1 0 17 (8.5)2 88 (44) 37 (18.5)3 88 (44) 69 (34.5)4 22 (11) 63 (31.5)5 2 (1) 14 (7)Total 200 (100) 200 (100)

PAI, periapical index.

analTreatmentQuality,CoronalRestorationQuality,andPostPresence

forEach

ToothLocation

alnumber

ofteeth

Inad

equaterootcanal

trea

tmen

t*(%

)Adeq

uaterootcanal

trea

tmen

t*(%

)Inad

equatecoronal

restoration*(%

)Adeq

uatecoronal

restoration*(%

)Post

(%)

19

8(42)

11(58)

9(47)

10(53)

16(84)

33

21(63)

12(37)

10(30)

23(70)

30(90)

41

22(53)

19(47)

22(53)

19(47)

9(21)

32(66)

1(37)

1(33)

2(67)

2(66)

21

11(52)

10(48)

7(33)

14(67)

18(85)

83

57(68)

26(32)

48(58)

35(42)

38(45)

200

121

79

97

103

113

entrestorationappeared

radiographicallyintact;inadequatecoronalrestoration=thepermanentrestorationhaddetectableradiographicsignsofoverhangsoropen

marginsorcasesofrecurrentcaries;adequaterootcanalfilling

=allcanals

oids

werepresent,andtherootcanalfillingendedbetween0and2mmshortoftheradiographicapex.Rootfillings

thatdidnotfulfillthesecriteriaweredefined

asinadequate.

Clinical Research

100 radiographs numbered consecutively were used for calibration bythe observers. A scoring sheet was used with a corresponding radio-graph.

Only cases with a PAI score $2 determined based on the initialperiapical status survey were included. In multirooted teeth, the PAIscore was determined based on the root with the worst score. For casesin doubt, a higher score was assigned. The dynamics in the periapicalstatus between the 2 consecutive status surveys was defined as‘‘improved’’ when the PAI score decreased, ‘‘unchanged’’ when thePAI score remained unchanged, or ‘‘worse’’ when the PAI scoreincreased. For cases that presented with a PAI score of 5 both at theinitial and the consecutive status surveys, the dynamics in the periapicalstatus between the 2 consecutive status surveys was defined as following:‘‘improved’’ when the size of the periapical lesion decreased, ‘‘un-changed’’ when the size of the periapical lesion was unchanged, or‘‘worse’’ when the size of the periapical lesion increased.

Data for the following variables of interest were collected from thepatients’ medical records: age, sex, follow-up period, presence of apost, and tooth location. The quality of the root canal filling was radio-graphically evaluated and was defined as ‘‘adequate’’ in case all canalswere obturated, no voids were present, and the root canal filling endedbetween 0 and 2 mm short of the radiographic apex. Root fillings thatdid not fulfill these criteria were defined as ‘‘inadequate’’ (22).

The quality of the coronal restoration (23, 24) wasradiographically evaluated and was defined as ‘‘adequate’’ when apermanent restoration appeared intact radiographically. The coronalrestoration was defined as ‘‘inadequate’’ in cases in which thepermanent restoration had detectable signs of overhangs or openmargins and in cases of recurrent caries.

The influence of the variables of interest on the difference in theperiapical status between the 2 consecutive status surveys was statisti-cally evaluated using logistic regression. To estimate the effect ofpossible variables of interest on periapical change, a multiple linearregression model was constructed with combination of the generalizedestimation equation method. This technique allowed us to take into ac-counts the clustering effect of several teeth within the same patient. Clas-sification of lesions to ‘‘worsening of lesion’’ (yes/no) had beenperformed. Logistic regression with the generalized estimation equationmethod was used in order to model this binary variable. Statistical sig-nificance was set to P < .05.

TABLE2.

DistributionofRootC

Tooth

location

Tot

Maxillary

incisor

Maxillary

premolar

Maxillary

molar

Mandibularincisor

Mandibularpremolar

Mandibularmolar

Total

*Adequatecoronalrestoration=aperman

appeared

radiographicallyobturated,no

v

ResultsA total of 720 periapical status surveys were initially identified; 74

that had a consecutive periapical status survey were further analyzed. Inthese periapical status surveys, 398 teeth had been endodonticallytreated; 200 of these teeth with periapical lesions present at the first sur-vey fulfilled the inclusion criteria.

Thus, the final study cohort consisted of 74 patients (38 [51.45%]women and 36 [48.6%] men) with 200 evaluated teeth (Table 1).

JOE — Volume 39, Number 12, December 2013 Dynamics of Periapical Lesions 1511

Figure 1. Periapical status unchanged in a left maxillary premolar: (A) initial periapical status survey and (B) at the 5-year follow-up.

Clinical Research

Patients’ age ranged between 27 and 70 years (median = 48 years). Thetime interval between the 2 surveys ranged between 4 and 8 years (me-dian = 6 years). The distribution of post presence, RCT quality, and cor-onal restoration quality for each tooth location is shown in Table 2.

From a total of 200 evaluated teeth, the dynamics of the periapicalstatus between the 2 consecutive status surveys was observed as ‘‘un-changed’’ in 57 (28.5%) teeth (Fig. 1A and B), ‘‘worse’’ in 103(51.5%) teeth (Fig. 2A and B), and ‘‘improved’’ in 40 (20%) teeth(Fig. 3A and B). The PAI change between the 2 consecutive status sur-veys is shown in Figure 4 (P > .05).

Poor root canal filling (n = 123, 61%), or poor restoration(n = 97, 48%) adversely affected the dynamics of the periapical status(P < .05) (Fig. 5). Age, sex, tooth location, and post presence had nostatistically significant influence on the dynamics of the periapicalstatus (P > .05).

DiscussionThe relationship between AP and bacterial infections in the root

canal system is well established (25–27), and it is generally acceptedthat AP usually does not heal without intervention (1, 28, 29). Afterendodontic treatments, a clinical and radiographic follow-up is indi-

Figure 2. Periapical status worsened in a left maxillary molar: (A) initial periapi

1512 Tsesis et al.

cated to determine the treatment outcome (17). In case of persistentAP after endodontic treatment, additional endodontic treatment or toothextraction are usually the treatments of choice (16). In certain cases,especially in asymptomatic teeth, when the clinical and radiographichistory of the tooth is unknown, a long-term follow-up protocol maybe considered. However, because the long-term prognosis of teethwith persistent AP that are left without intervention is not fully eluci-dated, rational clinical decision making is difficult. Fristad et al (30) re-ported that some teeth deemed to be failures based on radiographicevaluation 10–17 years after treatment were judged as healed afteran additional 10-year follow-up. Thus, they showed the potential forlate healing of failed endodontic treatments left without interventionin an extended follow-up period. The present study was aimed to retro-spectively evaluate the long-term dynamics of periapical lesions inendodontically treated teeth left without intervention based on fullradiographic status surveys.

A full mouth series of periapical radiographs and not panoramicradiographs were chosen for evaluation because the latter are consid-ered less sensitive than periapical radiographs in detecting periapicalosteolytic lesions, especially in the anterior region (31). Eckerbomand Magnusson (32) showed that the reliability of only 1 orthoradialintraoral radiograph was poor when evaluating the lateral seal of an

cal status survey and (B) at the 4-year follow-up.

JOE — Volume 39, Number 12, December 2013

Figure 3. Periapical status improved in a right mandibular molar: (A) initial periapical status survey and (B) at the 7-year follow-up.

Clinical Research

endodontic treatment. The absolute diagnostic value of a single periap-ical view of a root-filled tooth was proven to be limited (33). Thus, in thepresent study, the use of full periapical status surveys enabled diagnosesbased on at least 2 periapical x-rays with different angulations.

An assessment of the long-term outcome of endodontic treatmentsbased on a radiographic evaluation at a single time point after the treat-ment is limited because it provides only a static image on the course of adynamic process. However, in the current study, the data were collectedat 2 different time points, thus enabling the evaluation of the dynamics ofthe periapical status. In the present study, the time periods between the2 PA surveys ranged from 4–8 years. Orstavik (17) found that in somecases, healing of AP after RCT required 4 years for completion. Strind-berg (1) showed that the healing process of teeth with AP undergoingRCT stabilized at 4 years after the RCT.

In the present study, not only the presence but also the degree ofapical periodontitis was assessed. The PAI score was used for quanti-fying the periapical status of the included teeth. The PAI system is anexample of a set of criteria that fulfills the requirements for use in epide-miologic research (measurable, mutually exclusive, meaningful relatedto the condition under investigation, reproducible, and communicable)(34). The PAI score is based on the study of Brynolf (35) that comparedhistological and radiographic appearances of periapical changes in hu-man autopsy materials in order to disclose to what extent histological

Figure 4. Periapical index (PAI) change between the 2 consecutive statussurveys.

JOE — Volume 39, Number 12, December 2013

changes are reflected radiographically. The PAI score consists of 5 cat-egories, each representing a step on an ordinal scale ranging fromnormal periapical bone to severe AP. Radiographs from Brynolf’s orig-inal material represented each of the 5 groups and were used as visualreferences in the development of the PAI score (21). The cases includedin the current study were assigned to PAI score categories using the vi-sual references for the 5 categories within the PAI scale. If there was anydoubt about the appropriate score to assign to a tooth, the higher scorewas chosen. This rule was based on the finding that histological exam-ination usually reveals a more advanced lesion than the radiographicexamination (35).

In the present study, about one half of the RCT teeth exhibited AP.This finding is consistent with several epidemiologic studies from

Figure 5. Periapical index (PAI) change in relation to root canal filling qual-ity and coronal restoration quality. Adequate coronal restoration = a perma-nent restoration appeared radiographically intact. Inadequate coronalrestoration = the permanent restoration had detectable radiographic signsof overhangs, open margins, or in case of recurrent caries. Adequate root ca-nal filling = all canals appeared radiographically obturated, no voids were pre-sent, and the root canal filling ended between 0 and 2 mm short of theradiographic apex. Root fillings that did not fulfill these criteria were definedas inadequate.

Dynamics of Periapical Lesions 1513

Clinical Research

various countries in Europe, America, and Asia that found AP in 39%–64.5% of RCT teeth (2–4, 36–47).

In the current study, age, sex, and tooth location had no influenceon the dynamics of the PAI score between the periapical status surveys.This observation is consistent with previous reports that found that thepreviously mentioned factors had no effect on treatment outcomes (13,48, 49).

In this study, there was no correlation between the presence of apost and the periapical status. Although some studies reported anincreased prevalence of AP in teeth restored with posts (36, 42),several other studies found no effect of post presence on theperiapical status of endodontically treated teeth (13, 50, 51).

In the present study, worsening of the periapical status was mostlyrelated to inadequate endodontic treatment. This is consistent withseveral other studies (23, 24). Bergstrom et al (52) reported that ho-mogenic root filling had a more significant effect on lower AP frequencythan the length of obturation. Petersson et al (41) found that incom-pletely obturated root-filled teeth developed AP significantly more oftenthan completely obturated root canals. Ray and Trope (23) and Tron-stad et al (24) stressed the importance of root canal filling and coronalrestoration quality in connection with AP.

Another important factor in the development of AP in root canal–treated teeth is coronal leakage (8, 23, 53). Although some studiesshowed that well-prepared and filled root canals can resist bacterialpenetration even without intact coronal restoration (54), other studiesstressed the importance of adequate coronal restoration for periapicalhealing (23, 24). Future large-scale studies are necessary to elucidatethe effect of other potentially influencing factors, such as the combina-tion of poor restoration and good root canal filling.

The primary goal of endodontic treatments is the retention of teethby the prevention or treatment of periapical pathology (1, 22). Adecision of intervention for an endodontically treated tooth withperiapical radiolucency should be based on the technical feasibilityof the treatment, systemic factors, and patient values and preferences(16, 28, 34, 55, 56). The results of the current study indicate that aclinical decision regarding the treatment of asymptomatic teeth withperiapical radiolucency should be based on the evaluation of therestoration and root canal filling quality. In this study, it was shownthat teeth with unsatisfactory root canal fillings and/or restorationshave a high potential for continuous deterioration of their periapicalcondition. However, for functioning teeth with good root canal fillingand restoration, when an endodontic treatment is not feasible, theoption of continuing follow-up may be considered.

ConclusionPoor root canal filling and poor restoration adversely affect the

long-term dynamics of periapical lesions left without intervention inendodontically treated teeth. In such cases, there may be a strongerargument in favor of an intervention.

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

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