Fate of the Tissue in Lateral Canals and Apical Ramifications in Response to Pathologic

15 Pages·2009·4.35 MB·English

Review Article
Fate of the Tissue in Lateral Canals and Apical Ramifications
in Response to Pathologic Conditions and Treatment
Procedures
Domenico Ricucci, MD, DDS,* and Jose´ F. Siqueira Jr, DDS, MSc, PhD†
Abstract
Introduction: This article reviews and reports on the Lateralandapicalramificationsofthemainrootcanalareformedafteralocalized
histopathologicandhistobacteriologicstatusofthetissue fragmentationoftheepithelialrootsheathdevelops,leavingasmallgap,orwhen
in lateral canals and apical ramifications (LC/AR) in bloodvesselsrunningfromthedentalsacthroughthedentalpapillapersist.Dentino-
diverse clinical conditions as well as in response to genesisdoesnotoccurinthisspecificarea,givingrisetoacanalcontainingsmallblood
endodontictreatment.Methods:Intotal,serialsections vessels and sometimes nerves. Although ramifications contain connective tissue and
from493humantoothspecimensobtainedbyextraction bloodvessels,thisisnotusuallyregardedascollateralbloodsupplyandconsequently
orapicalsurgerywerescreenedforthepresenceofLC/ provideslittlecontribution,ifany,topulpfunction,exceptpossiblyfortheramifications
AR. Results: LC/AR were observed in about 75% of located in the apical 1–2 mm of the canal (1, 2). Ramifications can be observed
theteeth.Inclinicallyvitalteeth,vitaltissuewasconsis- anywherealongthelengthoftheroot,buttheyoccurmorecommonlyintheapical
tentlyfoundinLC/AR.Inteethwithperiodontaldisease, portionandinposteriorteeth(3).In73.5%ofthecases,ramificationsarefoundin
thewholepulpbecamenecroticonlywhenthesubgingi- theapicalthirdoftheroot,in11%inthemiddlethird,andin15%inthecoronalthird
val biofilm reached the main apical foramen. In teeth (4).Forconsistency,werefertoramificationsasfurcationcanals,lateralcanals,and
with pulp exposure by caries, the tissue in LC/AR re- apicalramifications.Thisarticledealswiththelattertwo.
mainedvitalasfarasthepulptissueinthemaincanal Ramificationscomprisepotentialpathwaysthroughwhichbacteriaand/ortheir
didso.WhenpulpnecrosisreachedtheleveloftheLC/ productsfromthenecroticrootcanalmightreachtheperiodontalligamentandcause
AR,thetissuethereinwaseitherpartiallyorcompletely disease,andlikewise,bacteriafromperiodontalpocketsmightreachthepulp.Lateral
necrotic. Chemomechanical preparation partially canalsandapicalramificationsarearguablydifficulttoreach,clean,disinfect,andfill
removed necrotic tissue from the entrance of LC/AR, duringtreatment.Theirpossibleclinicalsignificancehaslongcalledtheattentionof
whereastheadjacenttissueremainedinflamed,some- cliniciansandresearchersastohowandwhethertheseramificationsshouldbeap-
timesinfected,andassociatedwithperiradiculardisease. proachedandwhatisthefateofthetissuepresentthereinaftertreatment.Thepresent
VitaltissueinLC/ARwasnotremovedbypreparation.In studyreviewsandreportsonthehistopathologicandhistobacteriologicstatusofthe
casesinwhichlateralcanalsappearedradiographically tissueinlateralcanalsandapicalramificationsindiverseclinicalconditionsaswell
‘‘filled,’’ they were actually not obturated, and the re- asinresponsetoendodontictreatment.Inlightoftheseobservations,theinfluence
mainingtissueintheramificationwasinflamedanden- oflateralcanalsandapicalramificationsontreatmentoutcomeisdiscussed.
meshedwiththefillingmaterial.Conclusions:Overall,
thebeliefthatlateralcanalsmustbeinjectedwithfilling
To Fill or Not to Fill: Is This the Question?
material to enhance treatment outcome was not sup-
ported by literature review or by our histopathologic The actual need to fill lateral canals has been a bone of contention among
observations. It appears that strategies other than endodontists.Schilder(5–7)postulatedthatthemainobjectiveofendodontictreat-
finding a technique that better squeezes sealer or mentproceduresshouldbethecleaningandfillingoftherootcanalinitsentireextent,
gutta-perchawithinLC/ARshouldbepursuedtoeffec- alsoincludingalllateralcanalsandapicalramifications.Afterhim,someadvocatedthat
tivelydisinfecttheseregions.(JEndod2010;36:1–15) ‘‘thosewhodo3-Dobturationtechniqueshavehistoricallyclaimedtechnicalandeven
moralsuperiorityoverthosewhodotechniquesthatonlyfillprimarycanals’’(8).Thus,
KeyWords clinician’sskillorthetechnicalabilityoffillinglateralcanalshasbeenconsideredby
Apical periodontitis, apical ramification, endodontic manyasameasureofendodonticexcellence.Personalopinionsbasedonimpression
treatment,lateralcanal,periodontaldisease,pulpitis leftaside,ithasbeenreportedthat‘‘unfilledlateralcanals’’mightbeassociatedwith
post-treatmentdisease(9).Ithasalsobeenclaimedthatlateralcanalsharboringin-
flamedand/orinfectedmaterialmightcausepainduringendodontictreatment(10).
Onthebasisoftheseassumptions,theideathatlateralcanalsandapicalramifi-
From*Privatepractice,Rome,Italy;andthe†Departmentof cations should be filled for successful endodontic therapy has been accepted by
EndodonticsandMolecularMicrobiologyLaboratory,Facultyof
manycliniciansandresearchersinanalmostdogmaticmanner.Inthiscontext,amyriad
Dentistry,Esta´ciodeSa´ University,RiodeJaneiro,Brazil.
Address requests for reprints to Dr Domenico Ricucci, ofinvitrostudieshaveaimedatevaluatingtheabilityofdifferentobturationtechniques
PiazzaCalvario,7,87022Cetraro(CS),Italy.E-mailaddress: offillinglateralcanals(11–17).Curiously,mostofthesestudiesreportedthatnosignif-
[email protected]. icantdifferenceswereobservedfortheefficacyofdifferenttechniquesinforcingsealer
0099-2399/$0-seefrontmatter
intothelateralcanal,eventhoughthermoplasticizedtechniquesobviouslyalsotended
Copyright ª 2010 by the American Association of
toforcegutta-perchainmanyspecimens.Ithasalsobeenfoundthatlateralcanalsare
Endodontists.Allrightsreserved.
doi:10.1016/j.joen.2009.09.038 filledlessfrequentlyafteruseofcalciumhydroxidemedication(18).
JOE—Volume36,Number1,January2010 LateralCanals:AReview 1
Review Article
Figure1. (A)Maxillarylateralincisorwithnecroticpulpandalargeradiolucencyinvolvingtheapexandthemesialaspectoftheroot.Patientpresentedwith
spontaneouspain.Toothwastendertopercussion.Presenceoflateralcanals,althoughnotvisibleintheradiograph,islikelyunderthiscircumstance.(B)
Afterinstrumentationand1-weekcalciumhydroxidemedication,thecanalwasobturatedwithlaterallycompactedcoldgutta-perchaandasealer.Notethatno
lateralcanal/ramificationswereinjectedwithfillingmaterial.(C)Three-yearfollow-upradiograph.Thelaterallesionappearscompletelyhealed.(D)Thisis
a case in which the canal of a maxillary central incisor with necrotic pulp was instrumented and medicated with an iodoformic paste. After rubber dam
removal,somemedicamentpushedthroughthesinustractwasseenonthebuccalmucosa.(E)Thematerialpenetratedintoalaterallesionthroughalarge
lateralcanalandfollowedthecourseofthesinustract.Becauseofitshighradiopacity,itpermittedtoobtainsortofa‘‘fistulography’’.Thecanalwasthen
obturatedafter40days,whenthesinustractappearedclinicallyhealed,withchloroformmodifiedlateralcompactiontechniqueandsealer.Postoperative
radiograph revealed that the filling material penetrated into the large lateral canal (not shown). No symptoms emerged in the postoperative period. (F)
Eleven-year follow-up radiograph showing that the lateral lesion healed completely, with the radiographic image of a lamina dura following the entire
rootoutline.
Nevertheless,thereis noconsensusasto theneedto filllateral provide these bacteria with frank access to the periradicular tissues
canals to optimize the treatment outcome. Weine (10) admitted that (21–26).Therefore,disinfectionoflateralcanalsandapicalramifica-
althoughthefrequencyoflateralcanalshasbeendemonstratedtobe tionsincasesofpulpnecrosisandapicaland/orlateralperiodontitis
high, they are not so frequently revealed radiographically after root shouldbeconsideredanimportantgoalofthetreatment,althoughdiffi-
canal filling. Even so, failure to fill lateral canals has been assumed culttoachievewithcurrenttreatmentprocedures.Whatremainstobe
nottoleadtoendodontictreatmentfailurecharacterizedbyapost-treat- determined is whether forcing the filling material into ramifications
mentlaterallesioninthehugemajorityofcases. exertsanysignificant influenceontheoutcomebykillingbacteriain
Admittedly,fillingramificationswouldbeadesirableobjectiveof theseramificationsasaresultoftheantibacterialeffectsofthematerial
treatmentonlywhenthereisachanceforbacterialtrafficfromthecanal orbypromotinganeffectivelateralantibacterial(bacteria-tight)seal.It
totheperiodontalligament,ie,inpreviouslynecroticinfectedcasesin isimportanttopointoutthattheantibacterialeffectsoffillingmaterials
whichbacteriawereleftundisturbedinthemaincanalorintherami- are usuallyweak andonly transient,reachingapeakof effectiveness
fication.However,clinicalexperiencerevealsthatlaterallesionsmight beforesetting(27–33).Moreover,attainmentofapredictableantibac-
healafterendodontictreatment,evenwhenthelateralcanalsarenot terialsealprovidedbythematerialinjectedintothesmallandusually
filled(Fig.1A–C).Indeed,CampsandLambruschini(19)statedthat tortuousramificationishighlyunlikelyandhasnotbeendemonstrated.
fillingoflateralcanalsisnotalwaysnecessaryforasuccessfulrootcanal Asonecaninferfromthisdiscussion,althoughtheinfluenceof
treatment. A study examining root canal–treated teeth from human fillinglateralcanalsontreatmentoutcomehasbeensubjectofdebate
cadaversreportednorelationshipbetweenunfilledlateralcanalsand andpersonalopinion(34),thereisnoclearscientificevidenceasto
thestatusofinflammationattheperiradiculartissues(20). this matter. Because bacteria located in lateral canals and in apical
However,itmustbestatedthatlateralcanalsandapicalramifica- ramificationscancertainlyinfluencethetreatmentoutcome,itseems
tionshavebeenimplicatedwithendodontictreatmentfailurewhenthey advisable that efforts should be made to apply therapeutic strategies
aresufficientlylargetoharborsignificantnumbersofbacteriaandto to reach and incorporate these areas in the disinfection process.
2 RicucciandSiqueiraJr. JOE—Volume36,Number1,January2010
Review Article
Figure2. Maxillaryfirstmolarina35-year-oldpatient.Toothhadbeentreatedendodontically19yearsbeforeandhadremainedasymptomaticforthewhole
perioduntilseveresymptomsappeared.Clinicalexaminationrevealedanobliquefracture,andthetoothwasextracted.(A)Afterextractionpathologictissuewas
seenonthelateralaspectofthepalatalrootapex.Thiswasmoreevidentattheendofthedemineralizationprocedureafterclearingofthespecimenbefore
embeddinginparaffin.(B)Histologicserialsectionsrevealedalateralcanalconnectingthemaincanalandthelesion(Taylor’smodifiedBrown&Brenn;original
magnification,(cid:2)25).Insetshowsahighermagnificationoftheareaindicatedbythearrowin(B).Bacteriaareseenattheinterfacebetweentherootcanalwalland
thefillingmaterial(Taylor’smodifiedBrown&Brenn;originalmagnification,(cid:2)1000).(C)Sectiontakenapproximately30sectionsfromthatin(B),displaying
partofthelateralcanalcourse,andtheconnectionwiththemaincanal(Taylor’smodifiedBrown&Brenn;originalmagnification,(cid:2)100).(D)Highermagni-
ficationofthelateralcanalcontents.Inflammatorytissuecanbevisualized,butbacteriaareabsent(Taylor’smodifiedBrown&Brenn;originalmagnification,
(cid:2)1000).
Whetherthiscanbeachievedbyforcinggutta-perchaand/orsealerinto instead of filled when referring to the observation of filling material
theramificationishighlyquestionableandremainstobeproved. in ramifications. Thisis becauseactualfillingof lateralcanalsunder
in vivo conditions has not been consistently demonstrated. In fact,
Considerations Based on Clinical Observations
our histopathologic observations clearly demonstrated that lateral
Lateralcanals,withfewexceptions,arenotvisibleinthepreoper- canals and apical ramifications were never completely filled by
ative radiographs (Fig. 1A). The occurrence of lateral canals can be endodonticmaterials.
usuallysuspectedonlywhenthereisalocalizedthickeningoftheperi- Oneimportantquestionthatarisesastotheissueoflateralcanals
odontal ligament on the lateral surface of the root or when a frank is,giventheirhighfrequency,whylateralperiodontitislesionsassoci-
lateralperiodontitislesionispresent(Fig.1A).Afterrootcanalobtura- ated with these ramifications are not so frequent. There is no clear
tion,lateralcanalscanalsobevisualizedonradiographswhenaconsis- answertothisquestion,butitmightberelatedtothesizeandpatency
tent amount of filling material is forced into the ramifications by oftheramificationaswellasthehistologic/microbiologicconditionof
compaction(usuallysealerbutalsogutta-perchainthermoplasticized itscontentatacertainmomentofthediseaseprocess.Amorphologic
techniques)(Fig.1D–F). studyof100permanentmolarsrevealedthat79%hadlateral/accessory
Lateral canals and apical ramifications might be revealed by foraminawithdiametersrangingfrom10–200mm(35).Thelargest
avarietyoffillingtechniquesandareprobablymorefrequentlyindi- diameterwasnearlytwiceto3timessmallerthanthemeandiameters
cated in necrotic cases than in vital pulps; this supposition is based reported for the main apicalforamen (36–38). These differences in
onbothclinicalimpressionandtheallegeddegreeofresistanceoffered diameters between the main apical foramen and lateral/accessory
by the type of tissue present in the ramification (10). It is salient to foramina might help explain why apical periodontitis is observed far
emphasizeourusageofthetermsrevealed,indicated,andinjected morethanlateralperiodontitis.
JOE—Volume36,Number1,January2010 LateralCanals:AReview 3
Review Article
Figure3. (A)Maxillaryfirstpremolarin16-year-oldgirl.Toothappearstobetreatedendodonticallyandrestoredwithascrew-postandcomposite.Twolarge
separateradiolucencies,oneapicalandonelateral,arepresent.Toothisasymptomatic.(B)Nonsurgicalretreatmentwasperformed.Canalswereobturatedafter2
weeksofcalciumhydroxidemedication.Notethatnolateralcanalsappearedinjectedwithobturationmaterials.Toothwasrestoredwithacastpostandcoreand
aceramo-metalliccrown.(C)Eight-monthfollow-up.Considerableboneformationhastakenplace.(D)Patientpresented2yearsand3monthsaftertreatment
withtherestorationmissing.Radiographshowscompletehealingofthe2radiolucencies.
Large and patent lateral foramina might, however, allow larger Weine(40)reportedon3typesoflaterallesionsthatcanberadio-
numbersofbacteriaandbacterialproductstoreachandcontactalarger graphicallyobserved.Theseconditionsmightrepresentdifferentstages
areaofthelateralperiodontalligamenttocausedisease.Theamountof untiltheultimatethirdtypeofconditionemerges:
bacterialirritantsinsmallramifications,withsmallvolumecapacityand
(1) Lateral lesion with no apical lesion: as the infection progresses
smallexitingforaminalarea,mightbeinsufficienttoinducesignificant
apically, it might reach a sufficiently large lateral canal to allow
diseasetobediscernibleradiographically.Thus,adefinitelaterallesion
asubstantialamountofbacteriaandbacterialproductstoreach
oftenindicatesthepresenceofasignificantlylargelateralcanalwithsuffi-
the lateral periodontium to cause inflammation. In these cases,
cientinfectednecrotictissuetogiverisetoperiodontalinflammation.
itispossiblethatthepulptissueapicaltotheramificationisstill
Giventhedirectcommunicationtotheperiodontalligament,the
vital,butinsomecasesitisarguablyalreadynecroticandinfected,
tissue in lateral canals is nourished by the rich periodontal blood
andthedevelopmentofanapicallesionisjustamatteroftime,orit
supply, offering a significant resistance against necrosis and further
isalreadyestablishedbutstillcannotbevisibleonradiographs.
bacterialinvasion.Itappearsthatthetissueinlateralcanalsbecomes
(2) Separate lateral and apical lesions: if the pathologic process
necrotic and thoroughly colonized by bacteria only in cases with
advanceswithoutprofessionalintervention,anapicalperiodontitis
long-standingpulpnecrosis(24,25).Thepresenceofvital,albeitin-
lesioncanalsobevisibleradiographically.Thismeansthatsuffi-
flamed,tissueintotheramificationisalsotheexplanationwhyalateral
cientnumbersof bacteriaand theirproductsare concomitantly
lesion might heal without squeezing materials into any lateral canal.
egressing from the apical and lateral foramina to cause disease
Bacteriainthemaincanalelicitinflammationinthetissuewithinthe
(Fig.3).
lateralcanal.Inflammationmightextendtotheperiodontalligament,
(3) Coalescence of lateral and apical lesions: in some cases, the
beingsustainedbybacterialproducts(notnecessarilybacterialcells)
second condition can progress to this third one, also regarded
thatdiffusethroughthetissuetoreachtheperiodontalligament.For
asa‘‘wraparound’’lesion(40)(Fig.1A).
instance,low-molecular-weightbacterialproducts,suchaspolyamines,
hydrogensulfide,butyrate,propionate,andN-formyl-methionyl-leucyl- Inalltheseconditions,assumingthatthesizeofthelateralcanalis
phenylalaninepeptides,mightpromptlydiffusethroughtheconnective largeenoughandthatitmightfrequentlycontainnecroticpulptissue,
tissueandconceivablyevokeinflammationatacertaindistancefromthe thereisahighpossibilityforthesecanalstobeinjectedwithfillingmate-
placewherethebacterialcellsarelocated(39).Theseproductsmight rials,regardlessofthetechniqueused.Asaforementioned,thevalidity
be toxic to host cells and tissues, might stimulate the synthesis and offillingtheselateralcanalsandwhethertheyareactuallysealedare
releaseofproinflammatorycytokines,andmightactaschemoattrac- onlyconjectural.
tantstopolymorphonuclearleukocytes(PMNs)(39).Alltheseevents
Histopathologic and Histobacteriologic
mightgiverisetoalaterallesion,whichinturnisnotassociatedwith
Observations
infectednecrotictissueintheramification.Inthesecases,thelateral
lesionsimplyhealsbecauserootcanalprocedures,removingthebacte- There are no studies in the endodontic literature consistently
rialcontentofthemaincanal,interruptboththeaggressioncausedto showingthefateofthetissueinlateralcanalsandapicalramifications,
the tissue in the ramification and the egress of bacterial products as well as the tissue adjacent to these ramifications, in response to
throughthelateralcanalsuptotheperiodontalligament.Fig.2illus- different pathologic conditions or treatment approaches. This review
tratesthissituation.Alaterallesionisdiscernibleonthepalatalroot takesadvantageofthelargenumberofspecimenscomposingthehisto-
ofamaxillaryfirstmolar,andnobacteriaareseeninthelateralcanal, logiccollectionof oneof theauthors(D.R.).In total,serialsections
whichcontainsinflamedtissue.Bacteriaindeedoccurredinthemain from493humanteethsubjectedtoprevioushistopathologicanalysis
canalbetweentherootcanalwallandtheobturation. were screened for the presence of lateral canals and/or apical
4 RicucciandSiqueiraJr. JOE—Volume36,Number1,January2010
JO TABLE1. FrequencyofLateralCanalsand/orApicalRamifications(LC/AR)andDistributionof493ExaminedTeethAccordingtoClinicalConditions
E
— Rootcanal- Rootcanal-
Vo Untreatedteeth Untreatedteeth treatedteeth treatedteeth Teethextractedafter
lu
m withclinically withclinically classifiedas classifiedas chemomechanical
e
3 vitalpulp necroticpulp success failure procedures Total
6
,
Nu Toothtype*
m
b Maxillary
e
r Incisors 6(2,33%) 12(3,25%) 38(34,89.5%) 24(19,79%) 11(7,64%) 91(65,71%)
1
,Ja Canines 3(1,33%) 9(9,100%) 13(8,61.5%) 5(4,80%) 2(1,50%) 32(23,72%)
nu Premolars 12(8,67%) 28(21,75%) 37(33,89%) 17(13,76.5%) 4(4,100%) 98(79,81%)
a
ry Molars 12(11,92%) 41(32,78%) 7(4,57%) 7(6,86%) 2(2,100%) 69(55,80%)
20 Mandibular
1
0 Incisors 2(1,50%) 5(4,80%) 1(1,100%) 2(1,50%) - 10(7,70%)
Canines 4(3,75%) 2(1,50%) 3(2,67%) 3(1,50%) - 12(7,58%)
Premolars 8(6,75%) 16(12,80%) 39(17,44%) 5(4,80%) 1(1,100%) 69(40,58%)
Molars 34(28,82%) 55(48,87%) 10(8,80%) 12(8,67%) 1(1,100%) 112(93,83%)
Total* 81(60,74%) 168(130,77%) 148(107,72%) 75(56,75%) 21(16,76%) 493(369,75%)
Reasonsforextraction/biopsy
Nonrestorability(recurrent 22 125 117 32 — 296
cariesorrootfracture)
Periodontaldisease 13 20 3 — — 36
Orthodonticorprosthetic 13 — — — 21 34
treatmentplans
Patientacceptednotreatment 33 23 28 5 — 89
Needforapicalsurgery — — — 38 — 38
StatusoftissueinLC/AR
Vitaluninflamed 54 — 39 — 7 100
Vitalinflamed 6 29 9 12 2 58
Partiallynecrotic — 22 35 7 5 69
Necrotic — 79 24 37 2 142
Injectedwithfillingmaterial — — 31 7 — 38
Cementumformation — — 51 21 — 72
narrowingthelumen
Bacteriapresent — 59 — 34 1 94
*Numberofteethexamined(numberoftheseteethwithLC/AR-%)
L
ate R
ra e
l
C v
ana ie
ls: w
A
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i
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5 e
Review Article
Figure4. (A)Maxillarysecondpremolarwithcariespenetratingtothepulp.Patientcomplainedofseverepainanddidnotacceptanytreatmentbutextraction.
(B)Longitudinalserialsectionsshowalateralcanalatthemiddleportionoftheroot(hematoxylin-eosin;originalmagnification,(cid:2)50).(C)Vitaluninflamedpulp
tissuecanbeobservedinthemaincanalaswellasinthelateralcanal(hematoxylin-eosin;originalmagnification,(cid:2)100).
ramifications.Specimenswereobtainedbyextractionorapicalsurgery. logic and histobacteriologic analysesasreportedpreviously (23, 24,
ReasonsforextractionareshowninTable1.Whenpresent,apicalpe- 41–43).Serialsectionswereexaminedunderlightmicroscopy.
riodontitislesionswereremovedstillattachedandintheoriginalrela- Table1displaysdetailedinformationonthedistributionofteeth
tionship to the root tip. Specimens included clinically intact teeth; andstatusofthetissueinlateralcanalsand/orapicalramificationsac-
untreatedteethwithcariouslesionsofvaryingdegrees(fromshallow cordingtoseveralaspects,includingtoothtypeandclinicalconditions.
to deep caries, including caries penetrating to the pulp) or coronal Thefrequencyoflateralcanalsand/orapicalramificationsisalsoshown
restorationswithdiversematerials;untreatedteethaffectedbyvarying onthebasisofdiverseaspects.Oneshouldbeawarethatthesecalcu-
degreesofperiodontaldisease;untreatedteethextractedwithapicalpe- lationsmighthavebeenunderratedbecauseonly1rootwasexamined
riodontitislesionsattached;teethextractedafterrootcanalchemome- forsomemulti-rootedteeth,andonlytherootapexwasavailablefor
chanicalproceduresbyusingdifferenttechniques;rootcanal–treated analysisof cases subjected to apicoectomy. Discounting these limita-
teethafterlong-termfollow-upperiods;and rootcanal–treatedteeth tions,theoverallfrequencyoflateralcanalsand/orapicalramifications
submitted to apical surgery that presented post-treatment disease. wasabout75%.Higherfrequencies(80%ormore)wereobservedfor
Immediatelyafterremoval,specimenswereprocessedforhistopatho- molarsandmaxillarypremolars.
Figure5. Sixty-year-oldwomanpresentingwithanabscessinthemandibularleftquadrant.Clinicallythemandibularsecondmolarshowedabuccalamalgam
restorationandalargedistalcariouslesion.(A)Radiographically,thecariouslesionappearedproximaltothepulpchamber,whichshowsextensivecalcification.A
smallradiolucencyispresentonthemesialrootapex,andbonelossisvisibleonthemesialaspectofthedistalroot.Patientdidnotacceptanytreatmentaimedat
conservationandrequestedextraction.(B)Toothwasprocessedforroutinehistology,andsectionsweretakenonamesiodistalplane.Overviewshowsthepulp
stoneoccupyinglargepartofthepulpchamberandalargelateralcanalendingonthemesialaspectofthedistalrootatthetransitionbetweentheapicalandthe
middlethird(hematoxylin-eosin;originalmagnification,(cid:2)6).(C)Areawherethelateralcanaljoinsthemaincanal.Inflamedconnectivetissueispresentfromthis
pointtoanapicaldirection.Noteresorptivedefectsindentin.Emptyspacesinthepulptissueareshrinkageartifacts(hematoxylin-eosin;originalmagnification,
(cid:2)50).
6 RicucciandSiqueiraJr. JOE—Volume36,Number1,January2010
Review Article
JOE—Volume36,Number1,January2010 LateralCanals:AReview 7
Review Article
Figure7. (A)Sectionpassingthroughthemaincanalofamaxillaryincisorwithnecroticpulp.Lateralcanalispresent(Taylor’smodifiedBrown&Brenn;original
magnification,(cid:2)25).(B)Detailofthemaincanalwiththelateralcanalentrance.Thelumenofbothisfilledwithadensebacterialbiofilm(Taylor’smodifiedBrown
&Brenn;originalmagnification,(cid:2)100).Insetsshowhigherpowerviewofthebacterialbiofilmadheredtothewallsofbothmainandlateralcanals(Taylor’s
modifiedBrown&Brenn;originalmagnification,(cid:2)400).
Considerations Based on Histopathologic intissuepressure,whichmightbecriticaltosuchatissueencasedin
Observations alowcomplianceenvironment.Iftheaggressionissevere,tissuepres-
suremightexceedthatofthin-walledvenules,whicharecompressed
TeethwithDifferentPreoperativeConditions
and collapse. Consequently, drainage is impeded, and stagnation of
In teeth with clinically vital pulps, vital tissue was consistently
bloodflownotonlypromotesincreasedbloodviscositybutalsocauses
foundinlateralcanalsandapicalramifications.Incasesofcarious
impairedremovalofwasteproducts(47).Thismightleadtocelldeath
pulp exposure, the tissue in lateral canals and apical ramifications
andtissuenecrosis.Inaddition,severalbacterialproductsaredirectly
remained vital as far as the pulp tissue in the main canal did so
toxictohostcellsandmightcontributetonecrosisinthearea.PMNs
(Fig. 4).
that are attracted to the area might also contribute to tissue damage
Thepulptissuereactspromptlytocariesdisease,andaccumula-
byreleasingenzymesandoxygen-derivedproductsthatdegradetissue
tionsofinflammatorycellscanbeseeninhistologicsectionsassoonas
components.Theintensityanddurationoftheaggressionwillinfluence
theenamelispenetratedandbacteriareachtheperipheralendofthe
theseverityofthetissueresponse.
dentinal tubules. In fact,at an early stage when a carious lesion can
Allthissequenceofeventsoccursinthetissueareaadjacenttothe
hardlybediagnosedclinically,chronicinflammatorycellsaccumulate
infectionfrontandnotintheentireextentofthepulp.Tissuepressure
in the subodontoblastic pulp area subjacent to the affected dentinal
nearthesiteofinflammationisalmostnormalandshowsnosignsof
tubules, in response to bacterial products traveling the tubules the
severe inflammation, indicating that tissue pressure changes do not
wholewayfromthefrontofcarieslesiontothepulp.Theseearlyreac-
spread rapidly (47). The difference in pressure between inflamed
tions will intensify in severity with the progression of the carious
and uninflamed areas can be a result of several edema-preventing
process,oftenintheabsenceofclinicalsymptoms,andarereversible,
mechanisms. For instance, the increase in tissue pressure might, in
provided bacteria are confined to the dentin. If the carious lesion
turn,forcefluidbackintolymphaticsandcapillariesinthenearbyun-
remainsuntreated,invariablybacteriapenetratethepulp,andaminor
inflamed tissue, consequently lowering the tissue pressure (48–50).
area of necrosis with bacterial colonization is established in a pulp
Resilienceofthegroundsubstanceofthepulptissuemightalsohelp
horn.Itmustbestressedthatthesurroundingtissueremainsrelatively
preventspreadofthepressurethroughoutthepulp(51).
unaltered.Thetimeelapsedbetweenpulpexposureandinfectionofthe
Itiscurrentlyrecognizedthattotalpulpnecrosisisresultantofthe
entirecanalisunpredictable,butitisusuallyaslowprocessthatvery
gradualaccumulationoflocalnecrosis(2,47,52).Afternecrosisof
oftenoccursbytissueincrements(44–48)(Fig.5).
apulptissuecompartment,bacteriaadvanceinthefrontofinfection.
Exposureofthepulptobacteriaaggravatesinflammationinthe
Consequently, the tissue immediately adjacent to the infected region
area subjected to aggression. Typical vascular events take place,
willbeinsultedandrespondwiththesameinflammatoryvascularevents
including vasodilation and increased vascular permeability, resulting
discussed above. In brief, after pulp exposure to caries, pulp tissue
inexudation.Thisleadstoedemaformation,withconsequentincrease
compartments are sequentially subjected to bacterial aggression and
Figure6. (A,B)Distobuccalrootofamaxillarymolarextractedwithanapicalperiodontitislesionattached.Sectionpassingthroughalateralcanal(arrows)
(hematoxylin-eosin;originalmagnification,(cid:2)25and(cid:2)100,respectively).(C)Highermagnificationoftheareaindicatedbythelowerarrowin(B).Lateralcanal
displaysnecrotictissueatthislevel(hematoxylin-eosin;originalmagnification,(cid:2)1000).(D)Highermagnificationoftheareaindicatedbytheintermediatearrow
in(B).Transitionfromnecrotictovitaltissue(hematoxylin-eosin;originalmagnification,(cid:2)1000).(E)Highermagnificationoftheareaproximaltotheperi-
odontalligamentindicatedbytheupperarrowin(B).Vitaltissuefreefrominflammatorycells(hematoxylin-eosin;originalmagnification,(cid:2)1000).(F,G)Section
taken approximately 60sections distantfromthat shown in(A,B).Second ramification ispresent onthe opposite root canal wall(arrow),with the lumen
completelyfilledbyabacterialbiofilm(Taylor’smodifiedBrown&Brenn;originalmagnification,(cid:2)25and(cid:2)50,respectively).
8 RicucciandSiqueiraJr. JOE—Volume36,Number1,January2010
Review Article
Figure8. (A)Rootapexofamaxillarysecondpremolarextractedwithanapicalperiodontitislesion.Specimenisclearedbeforeembeddinginparaffin.(B)
Sectionpassingthroughthemaincanal.Notetheapicalrootcanalcloggedwithabacterialbiofilm(Taylor’smodifiedBrown&Brenn;originalmagnification,
(cid:2)16).(C)Sectiontakenapproximately80sectionsdistantfromthatshownin(A),displayingalateralcanalthatconnectsthemaincanalandthelesion(Taylor’s
modifiedBrown&Brenn;originalmagnification,(cid:2)16).(D)Magnificationshowingbacterialcontentofthelateralcanal(Taylor’smodifiedBrown&Brenn;orig-
inalmagnification,(cid:2)25).(E)Sectiontaken30sectionsafterthatshownin(D),passingthroughtheforamenofthelateralcanal,alsocloggedwithadensebacterial
biofilm.Emptyspacesareshrinkageartifacts(Taylor’smodifiedBrown&Brenn;originalmagnification,(cid:2)100).
becomeinflamed,necrotic,andeventuallyinfected.Theseeventsoccur Observations of our specimens demonstrated that when pulp
byincrementsthatcoalesceandmigrateapicallyuntiltheentirepulpis necrosisreachedtheleveloftheentranceoflateralcanalsandapical
necroticandinfected.Therefore,inagivenmoment,differentstagesof ramifications, the tissue therein was partially or completely necrotic
thediseaseprocesscanbeobservedthroughoutthepulp.Forinstance, (Fig. 5). In some necrotic cases associated with lateral lesions, the
necrosiscanbepresentattheareaofpulpexposure,thecoronalpulp tissue within ramifications was partially necrotic, bacteria were seen
canbeseverelyinflamedinresponsetobacterialinvasion,buttheradic- colonizingtheramification,andinflamedtissuewasalsoobservedadja-
ularpulpmightremainuninflamed(45). cent to bacteria. In other cases, the ramification lumen was virtually
Figure9. Mandibularsecondmolarwithnecroticpulpina45-year-oldwoman.Patientpresentedcomplainingofpainatchewing.Toothdidnotrespondto
sensitivitytestsandwastendertopercussion.Radiographshowedsmallapicalradiolucenciesonbothroots.Patientoptedfornotreatment,andthetoothwas
extracted.Toothwasprocessedforroutinehistology,andsectionswerecutonamesiodistalplane.(A)Overviewshowsalateralcanalinthedistalrootending
intheinterradicularareawherebonelossisvisible(hematoxylin-eosin;originalmagnification,(cid:2)6).(B)Detailoftheinterradiculararea(hematoxylin-eosin;
originalmagnification,(cid:2)25).(C)Magnificationfrom(B).Cavitiesoccupiedbynecroticdebrisinthecenter.Vitalinflamedtissueonthemesialaspectofthe
distalroot(hematoxylin-eosin;originalmagnification,(cid:2)50).
JOE—Volume36,Number1,January2010 LateralCanals:AReview 9
Review Article
Figure10. (A)Maxillarysecondmolarina38-year-oldwomancausingaperiodontalabscess.Pulpdidnotrespondtosensitivitytests.Toothwasdeemedun-
treatableandextracted.(B,C)Afterextraction,calculusisseencoveringtheentiredistalrootuptotheapex.(D)Histologicsectionsshowedawidelateralcanal
occupiedbyabiofilminthemesialrootatthefurcationarea(Taylor’smodifiedBrown&Brenn;originalmagnification,(cid:2)6).(E)Detailoflateralcanal(Taylor’s
modifiedBrown&Brenn;originalmagnification,(cid:2)100).(F)Highermagnificationofexitoflateralcanalinthefurcationarea.Wallsoftheramificationarecovered
byadensebacterialbiofilm(Taylor’smodifiedBrown&Brenn;originalmagnification,(cid:2)400).(G)Sectiontakenatacertaindistancefromthatin(D).Rami-
ficationsarepresentinthedistalroot(Taylor’smodifiedBrown&Brenn;originalmagnification,(cid:2)25).(H)Highermagnificationoflateralcanalindicatedby
arrowin(G),withitslumenfilledwithbacteria(Taylor’smodifiedBrown&Brenn;originalmagnification,(cid:2)400).(I)Sectionpassingthroughthemesialroot
apex.Contrarytowhatwasobservedinthedistalrootwheretheentirepulpwasnecrotic,thereappearstobesomevitalpulpintheapicalsegmentofthemesialroot
(Taylor’smodifiedBrown&Brenn;originalmagnification,(cid:2)25).(J)Magnificationofareaindicatedbyarrowin(I).Transitionfromnecrotictovitaltissue(Tay-
lor’smodifiedBrown&Brenn;originalmagnification,(cid:2)400).
cloggedwithbacteria,veryoftenarrangedinbiofilms.Thecaseillus- mained attached to the root apex of the distobuccal root. Serial
tratedinFig.6exemplifiesthese2differentsituations.Itisamaxillary sections demonstrated that the pulp in the main canal was necrotic,
molarwiththecrowntotallydestroyedbyacariousprocess,deemed andseveralramificationswerepresent.Inoneoftheseramifications,
nonrestorable. After extraction, the apical periodontitis lesion re- necrotic tissue was observed until approximately halfway of the
10 RicucciandSiqueiraJr. JOE—Volume36,Number1,January2010