Endodontic Treatment of Lower Anterior Teeth with Multiple Canals

The failure of endodontic treatment may be the result of “forgotten”, non­detected canals, inadequate biomechan­ ical instrumentation and irrigation or incomplete obtura­ tion. Variations in the number of roots and canals (posi­ tion, direction and morphology), and the presence of lateral or accessory canals and branches are often described in the literature [1]. In addition to good knowledge of canal morphology, it is necessary to realize the treatment complex­ ity, particularly if prosthetic reconstruction is required after endodontic treatment completion. Numerous researchers have studied morphology of the canal system of lower anterior teeth. Mandibular canine is usually described to have one root and one canal [2]. Vertucci [1], Pineda and Kuttler [3], Green [4] and D’Arcangelo et al. [5], in their studies, have indi­ cated the presence of two canals with one or two sepa­ rate openings in 15% of samples. Laurichesse et al. [6] have described the presence of one root and two canals in 2% of samples and two roots and two canals in 1% of cases. If two canals are present, they usually join into one opening [7]. D’Arcangelo et al. [5] have reported mandib­ ular canine with two roots and two canals. Holtzman [8] and Orguneser and Kartal [9] have described endodon­ tic treatment of a lower canine with three canals and one root. Heiling et al. [10] have shown an extremely rare case of a mandibular canine with two roots and three canals. Mandibular incisors have two canals in 11­58% accord­ ing to the literature, and they are in most cases joined into one single canal in the apical third at about 1­3 mm to the apex [1, 11, 12]. Miyashita et al. [13] have recorded two canals with one opening at the apex in 12.4% of the tested samples, while two canals with two separate openings at the apex have been found in only 3%. Ingle and Bakland [2] have found two canals in 23.4% of mandibular central and 14.7% of lateral incisors. A study by Indian authors [11] on 480 extracted mandibular incisors reported one canal present in 63.75%, two canals with one opening in 36.5% and two canals with two openings in 6.25% of cases. The presence of two roots and two canals have also been noted [14]. The presence of lateral canals, which were more common in middle third than in apical third, has also been described [11, 12]. A great problem is the fact that during endodontic treatment of these teeth, in a small percentage all canals are found and treated [11, 15]. This results in failure of endodontic treatment, with visible changes radiographi­ cally which are often surgically treated, even though the reason for failure is “forgotten” or non­instrumented canal. During access cavity preparation lingual axial angu­ lation of crowns for about 20 degrees, and mesial axial SUMMARY Introduction Knowledge of root canal morphology is one of the main prerequisites for successful endodontic treatment. We present the case of a patient with multiple canals in lower anterior teeth which were treated endodontically. Case Report To a 45-year-old patient endodontic treatment was applied on lower left lateral incisor, lower right central and lateral incisor and lower right canine. These teeth were previously prepared for prosthetic crowns. All involved teeth had two canals which were not visible on the primary radiographs. Gracility of remaining tooth structure and canals and the presence of two canals in each tooth required additional radiographs for verification of multiple canals. Careful biomechanical instrumentation and irrigation with use of lubrication due to narrow canals was performed. The canals were obturated with gutta-percha using lateral compaction technique and Acroseal (Septodont) paste. On the control checkup after eight months, the patient was asymptomatic, while clinical finding was normal. Conclusion Complexity of presented case was even more significant because these teeth were prepared to support prosthetic superstructure and crowns, and every “forgotten” canal is an iatrogenic error.


INTRODUCTION
The failure of endodontic treatment may be the result of "forgotten", nondetected canals, inadequate biomechan ical instrumentation and irrigation or incomplete obtura tion.Variations in the number of roots and canals (posi tion, direction and morphology), and the presence of lateral or accessory canals and branches are often described in the literature [1].In addition to good knowledge of canal morphology, it is necessary to realize the treatment complex ity, particularly if prosthetic reconstruction is required after endodontic treatment completion.
Numerous researchers have studied morphology of the canal system of lower anterior teeth.Mandibular canine is usually described to have one root and one canal [2].Vertucci [1], Pineda and Kuttler [3], Green [4] and D' Arcangelo et al. [5], in their studies, have indi cated the presence of two canals with one or two sepa rate openings in 15% of samples.Laurichesse et al. [6] have described the presence of one root and two canals in 2% of samples and two roots and two canals in 1% of cases.If two canals are present, they usually join into one opening [7].D' Arcangelo et al. [5] have reported mandib ular canine with two roots and two canals.Holtzman [8] and Orguneser and Kartal [9] have described endodon tic treatment of a lower canine with three canals and one root.Heiling et al. [10] have shown an extremely rare case of a mandibular canine with two roots and three canals.
Mandibular incisors have two canals in 1158% accord ing to the literature, and they are in most cases joined into one single canal in the apical third at about 13 mm to the apex [1,11,12].Miyashita et al. [13] have recorded two canals with one opening at the apex in 12.4% of the tested samples, while two canals with two separate openings at the apex have been found in only 3%.Ingle and Bakland [2] have found two canals in 23.4% of mandibular central and 14.7% of lateral incisors.A study by Indian authors [11] on 480 extracted mandibular incisors reported one canal present in 63.75%, two canals with one opening in 36.5% and two canals with two openings in 6.25% of cases.The presence of two roots and two canals have also been noted [14].The presence of lateral canals, which were more common in middle third than in apical third, has also been described [11,12].
A great problem is the fact that during endodontic treatment of these teeth, in a small percentage all canals are found and treated [11,15].This results in failure of endodontic treatment, with visible changes radiographi cally which are often surgically treated, even though the reason for failure is "forgotten" or noninstrumented canal.During access cavity preparation lingual axial angu lation of crowns for about 20 degrees, and mesial axial angulation for about 17 degrees should be considered.In order to detect lingual canal it is necessary to extend access cavity in incisogingival direction.

CASE REPORT
A 45yearold woman showed up at the Clinic for restor ative Dentistry and endodontics, School of Dentistry in Belgrade for endodontic treatment of the lower anterior teeth, previously prepared for prosthetic crowns.Lower left lateral incisor, lower right central and lateral incisor and lower right canine were proposed for endodontic treat ment.Teeth were vital and percussion test was negative.Analysis of preoperative diagnostic radiograph revealed one canal in the lower left lateral incisor (Figure 1), one canal in right central and lateral incisor and two separate canals in lower right canine were clearly visible on the radiograph (Figure 2).
After obtaining dry field and local anaesthesia, access cavity was prepared on the lower left lateral incisor.It was desirable to preserve the coronal part of the tooth as much as possible, without compromising the principles of endodontic treatment.By probing the bottom of the access cavity the entrance of the root canal was located.When a thin instrument #810 was placed in the canal, buccal inclination of the instrument was visible but the instrument could not be moved either in central or lingual direction.There was assumption about the existence of the lingual canal even though it was not visible on the radiograph.By careful exploration, lingual entrance was detected, two instruments were placed in the canals and another radiograph was taken (Figure 3).The entrance of the canal was instrumented by Gates Glidden bur #2.Working length was determined using apex locator Root ZX (Morita, Europe GmbH, Frakfurt, Germany).The canals were instrumented using flexible hand canal instru ments and Canal+ (Septodont) as lubricant.
Step back technique and irrigation with 0.5% NaOCl solution were applied for canal instrumentation.The canals were obtu rated using Acroseal (Septodont) paste and guttapercha and additional radiograph was taken (Figure 4).
Three lower right anterior teeth were endodontically treated in the next appointment.Preoperative diagnos tic images of the lower right central and lateral incisor showed that both of them had one canal, while in the right canine two separate canals were visible (Figure 2).Having experience with multiple canals in the lower left lateral incisor and visible two canals in the lower right canine, there was an assumption that all three teeth may have two canals.Endodontic treatment was conducted as described for the lower left lateral incisor.By inserting thin instruments in the canals, two canals were validated in the three lower right anterior teeth (Figure 5).Canals were instrumented, irrigated and obturated with gutta percha using lateral compaction technique and Acroseal paste.Radiography was performed from two different angles to be able to register two canals (Figures 6 and 7).Control checkup after eight months was performed and patient had no subjective problems.

DISCUSSION
Detecting two canals in clinical situations can be compli cated because of the superposition of canals on the radio graph.Careful analysis can reveal direction of a root canal where sometimes sudden disappearance of the canal may indicate a possible doubling the canal [16,17].In this case, at the same time, advantage and disadvantage was that the teeth were prepared for prosthetic crowns.It was difficult to prepare adequate access cavity because of pres ervation of the crown on one hand and not compromis ing endodontic treatment on the other hand.Instrument position during the initial exploration of the canal clearly indicated first slope of the canal to the buccal and second slope to the lingual.As few teeth were already shown to have two canals, including the canine, to verify the canal and obtain working length, several radiographs were taken from different angles.On some radiographs, it seemed as superposition, but on some the presence of two sepa rate canals was obvious.The presence of two canals in mandibular incisors is quite often [1,2,3] as shown in in vitro studies on extracted teeth, whereas in clinical prac tice one of the canals is often forgotten leading to the fail ure of endodontic therapy.
Two canals are more common for lower incisors than lower canine.It should be pointed out that the complexity of canal system in one tooth usually requires better anal ysis of remaining teeth and their root canals.

UVOD
Ne u speh en do dont skog le če nja mo že bi ti re zul tat tzv.za bo ra vlje nih (neo t kri ve nih) ka na la ko re na zu ba, ne do volj nog či šće nja i ob ra de i ne pot pu ne op tu ra ci je ka na la ko re na.Opi sa ne su broj ne va ri ja ci je bro ja ko re no va i ka na la zu ba (po lo žaj, pra vac pru ža nja, mor fo lo ški iz gled), bro ja la te ral nih i tran sver zal nih ka na li ća i ana sto mo za [1].Osim do brog po zna va nja mor fo lo ških oso bi na, neo p hod no je upo zna ti se i sa slo že no šću ka nal nog si ste ma, po seb no uko li ko je po treb na en do dont ska te ra pi ja i po tom pro te tič ka re kon struk ci ja zu ba.
Mno ge stu di je su opi sa le mor fo lo ške od li ke ka nal nog si ste ma do njih fron tal nih zu ba.Man di bu lar ni oč njak obič no ima je dan ko ren i je dan ka nal [2].Ver tu či (Ver tuc ci) [1], Pi ne da (Pi ne da) i Ka tler (Kut tler) [3], Grin (Green) [4] i D' Ar kan đe lo (D' Ar can gelo) i sa rad ni ci [5] u svo jim stu di ja ma usta no vi li su dva ka na la s jed nim ili dva odvo je na otvo ra u 15% is pi ti va nih uzo ra ka zu ba.Lo ri še so va (La u ric hes se) i sa rad ni ci [6] opi sa li su u 2% is pi ti va nih uzo ra ka dva ka na la u jed nom ko re nu, a u 1% uzo ra ka dva ko re na i dva ka na la.Ako po sto je dva ka na la, ona se obič no spa ja ju u je dan s jed nim otvo rom na vr hu ko re na [7].D' Ar kan đe lo i sa rad ni ci [5] na vo de pri mer dvo ko re nog man di bu lar nog oč nja ka sa dva ka na la.Holc man (Hol tzman) [8] i Or gu ne ser (Orgu ne ser) i Kar tal (Kar tal) [9] pri ka za li su slu čaj en do dont skog le če nja do njeg oč nja ka sa tri ka na la u jed nom ko re nu.Haj ling (He i ling) i sa rad ni ci [10] opi sa li su iz u zet no re dak slu čaj dvo ko re nog man di bu lar nog oč nja ka sa tri ka na la.
U li te ra tu ri se na vo di da 1158% man di bu lar nih se ku ti ća ima dva ka na la i da se u ve ći ni slu ča je va spa ja ju u je dan ka nal u apek snoj tre ći ni, na 13 mm od apek sa [1,11,12].Mi ja ši ta (Miyas hi ta) i sa rad ni ci [13] su u 12,4% is pi ti va nog uzor ka usta no vi li dva ka na la ko ja ima ju je dan otvor u vr hu ko re na, a u sve ga 3% uzo ra ka dva ka na la ko ja se otva ra ju sa dva odvo je na otvo ra

KRATAK SADRŽAJ
Uvod Po zna va nje mor fo lo ških oso bi na ka na la ko re na zu ba je dan je od osnov nih pred u slo va uspe šne en do dont ske te ra pi je.Pri kazujemo slu čaj pa ci jen ta sa vi še ka nal nim si ste mi ma do njih fron tal nih zu ba ko je je bi lo neo p hod no en do dont ski le či ti.Pri kaz slu ča ja Kod že ne sta re 45 go di na ura đe na je en do dont ska te ra pi ja na do njem le vom la te ral nom se ku ti ću, do njem de snom cen tral nom i la te ral nom se ku ti ću i do njem de snom oč nja ku.Zu bi su pret hod no bi li pri pre mlje ni za pro te tič ke kru ni ce.Svi uključe ni zu bi su ima li po dva ka na la ko ja ni su bi la vi dlji va na pri mar nom ra di o gra mu.Gra cil nost pre o sta le kru ni ce zu ba, gra cil nost kana la i za stu plje nost po dva ka na la u sva kom zu bu zah te va li su do dat na sni ma nja ra di po tvr de udvo je no sti.Bi la je neo p hod na pažlji va bi o me ha nič ka ob ra da uz pri me nu lu bri kan ta i iri gan sa zbog ote ža ne pro hod no sti ka na la.Ka na li su na pu nje ni la te ral nom kom pak ta žom gu ta per ke uz pri me nu pa ste Ac ro seal (Sep to dont).Na kon trol nom pre gle du osam me se ci ka sni je pa ci jent ki nja nije ima la su bjek tiv nih te go ba, a kli nič ki na laz je bio nor ma lan.Za klju čak Sa gle da va nje kom plek sno sti ova kvog slu ča ja ra di en do dont skog le če nja je zna ča jno, jer su ovi zu bi bi li da lje op te re ćeni pro te tič kim na do grad nja ma i kru ni ca ma, pa bi sva ki "za bo ra vlje ni" ka nal bio lekarska gre ška u okvi ru prepro te tič ke pripreme.
Ve li ki pro blem pred sta vlja či nje ni ca da se to kom en do dont ske te ra pi je na ovim zu bi ma u ret kim pri li ka ma pro na la ze i en do dont ski le če dva ka na la [11,15].To do vo di do broj nih ne u spe ha en do dont ske te ra pi je, ko ji su pra će ni ra di o graf ski vi dlji vim pro me na ma na periapeksu zu ba i če sto se hi rur ški re ša va ju, iako u osno vi sto ji tzv.za bo ra vlje ni neo bra đe ni ka nal.Pri li kom for mi ra nja pri stup nog ka vi te ta tre ba ima ti u vi du lin gvoak si jal nu an gu la ci ju kru ni ce od 20 ste pe ni, kao i me zioak si jal nu an gu la ci ju kru ni ce zu ba od 17 ste pe ni.Da bi se ot krio lin gval ni ka nal, neo p hod na je eks ten zi ja ka vi te ta u in ci zogin gi val nom sme ru.

PRIKAZ SLUČAJA
Že na stara 45 godina ja vi la se na Kli ni ku za bo le sti zu ba Sto ma to lo škog fa kul te ta u Be o gra du ra di en do dont skog le če nja do njih fron tal nih zu ba ko ji su pret hod no bi li is pre pa ri sa ni za pro te tič ke kru ni ce.Tre ba lo je en do dont ski zbri nu ti do nji le vi la te ral ni se ku tić, do nji de sni cen tral ni i la te ral ni se ku tić i do nji de sni oč njak.Vi ta li tet zu ba je bio oču van i ni je bi lo per ku tor ne ose tlji vo sti.Ana li zom pre o pe ra ci o nog di jag no stič kog ra di o graf skog snim ka u okviru prepro te tič ke pri pre me na do njem le vom la te ral nom se ku ti ću uočen je ja sno vi dljiv je dan ka nal (Sli ka 1).
Na snim ku do nje de sne stra ne usta no vlje ni su je dan ka nal cen tral nog i la te ral nog se ku ti ća i dva raz dvo je na ka na la do njeg oč nja ka (Sli ka 2).
Na kon pri pre me po lja ra da i pri me ne ane ste zi je pri stu pi lo se for mi ra nju pri stup nog ka vi te ta na donjem le vom la te ral nom se ku ti ću.Bi lo je po želj no oču va ti kru nič ni deo zu ba ko li ko je to mo gu će, da se ne ugro ze prin ci pi en do dont skog le če nja.Son di ra njem dna pristupnog ka vi te ta, gra cil nih is pre pa ri sa nih kru ni ca zu ba, po zi ci o ni rao se ulaz u ka nal.To kom po sta vlja nja tan kog ka nal nog in stru men ta #810 bi le su vi dlji ve in kli na ci ja in stru men ta ka bu kal noj po vr ši ni i gra cil nost ka na la, pri če mu in stru ment ni je mo gao da se po me ra cen tral no i lin gval no.Pret po stav ka je bi la da po sto ji i lin gval ni ka nal, iako se na snim ku on ni je vi deo.Pa žlji vim is pi ti va njem uočen je ulaz u lin gval ni ka nal, uba če na su dva ka nal na in stru men ta, što je re gi stro va no ra di o gra mom (Sli ka 3).Ulaz u ka nal je ob ra đen GejtsGli de no vim (Ga tes-Gli den) bo re rom #2.Rad na du ži na je od re đe na pri me nom apeks lo ka to ra Ro ot ZX (Mo rita, Euro pe GmbH, Frank furt, Ne mač ka).Po tom su za ob ra du ka na la ko ri šćeni flek si bil ni ka nal ni in stru men ti uz pri me nu lu bri kan ta Ca nal+ (Sep to dont).Pri me nom tzv.step back teh ni ke, bi o me ha nič ka ob ra da je upot pu nje na iri ga ci jom ras tvo rom Na OCl od 0,5%.Ka na li su po tom na pu nje ni pa stom Ac ro seal (Sep to dont), na kon če ga je na či njen ra di o gram ko nač nog ka nal nog pu nje nja (Sli ka 4).
U sle de ćoj se an si ra đe na su tri do nja de sna fron tal na zu ba.Na pre o pe ra ci o nom di jag no stič kom snim ku do nji de sni cen tral ni i la te ral ni se ku tić ima li su po je dan vi dljiv ka nal, dok je oč njak imao dva ja sno odvo je na ka na la (Sli ka 2).S ob zi rom na to da smo bi li upo zna ti sa si tu a ci jom na le voj stra ni i da su bi la vi dlji va dva ka na la kod oč nja ka na ra di o gra mu, po šlo se od pret po stav ke da sva tri zu ba ima ju po dva ka na la.En do dont sko le če nje je iz ve de no na isti na čin kao i kod pret hod nog zu ba.Uba ci va njem tan kih ka nal nih in stru me na ta po tvr đe na su po dva ka na la u sva tri do nja fron tal na zu ba sa de sne stra ne (Sli ka 5).Ka na li su ob ra đe ni i na pu nje ni ta ko đe la te ral nom kom pak ta žom gu ta per ke i pa stom Ac ro seal, te su na či njeni ra di o graf ski sni mci iz dva ugla, na ko ji ma su re gi stro va na po dva ka na la (Sli ke 6 i 7).Na kon trol nom pre gle du osam me se ci ka sni je pa ci jent ki nja ni je ima la ni ka kvih su bjek tiv nih tegoba.

DISKUSIJA
Pro blem u di jag no sti ko va nju dva ka na la u kli nič kim uslo vi ma obič no pred sta vlja su per po zi ci ja ka na la na ra di o gra mu.Pa žlji vom ana li zom ra di o gra ma, iz me đu osta log, pra ti se i pra vac pru ža nja ka na la ko re na, pri če mu se po ne kad mo že uoči ti pre kid kon ti nu i te ta, što mo že da uka že na even tu al no udva ja nje ka na la [16,17].U ovom slu ča ju isto vre me no ote ža va ju ća ali i olak ša va ju ća okol nost bi lo je to što su zu bi pre de vi ta li za ci je bi li is pre pa ri sa ni za pro te tič ke kru ni ce.Ti me je mo guć nost eks ten zi je pri stup nog ka vi te ta bi la ote ža na, jer je tre ba lo sa ču va ti kru nič nu sup stan cu, a da se pri tom ne ugro zi is hod en do dont skog le če nja.S dru ge stra ne, po zi ci o ni ra nje ka nal nog in stru men ta pri pr vom is pi ti va nju ka na la vid no je uka zi va lo na bu kal ni, a po tom i na lin gval ni na gib ka nal nog in stru men ta.Ka ko su u pi ta nju bi li dvo ka nal ni do nji zu bi, uklju ču ju ći i oč njak, tre ba lo je, ra di po tvr de ka na la i ra di o graf ske odon to me tri je, na pra vi ti ne ko li ko sni ma ka iz raz li či tih uglo va, što je u jed nom slu ča ju uka zi va lo na su per po zi ci ju, a u dru gom na po sto ja nje dva raz dvo je na ka na la.Po sto ja nje dva ka na la kod man di bu lar nih se ku ti ća se re la tiv no če sto ja vlja [1,2,3], što po tvr đu ju stu di je in vi tro na eks tra ho va nim zu bi ma, dok se u kli nič koj prak si če sto de ša va da se je dan od ka na la za bo ra vi, što do vo di do ne u spe ha en do dont ske te ra pi je.
Za raz li ku od man di bu lar nih in ci zi va, mno go se re đe ot kri va ju dva ka na la u do njem oč nja ku.Tre ba na gla si ti da slo že nost ka nal nog si ste ma kod jed nog zu ba obič no zah te va bo lju ana li zu pre o sta lih zu ba i even tu al no ot kri va nje slič nih.

Fi gu re 1 .
One ca nal in the to oth 32 as shown on pre o pe ra ti ve ra di o graph Sli ka 1. Na ra di o gra mu se vi di je dan ka nal do njeg le vog la te ral nog se ku ti ća Fi gu re 2. One ro ot ca nal in the te eth 41, 42 and two ro ot ca nals in the to oth 43 (pre o pe ra ti ve ra di o graph) Sli ka 2. Na pre o pe ra ci o nom ra di o gra mu se vi de po je dan ka nal zu ba 41 i 42 i dva ka na la zu ba 43

Fi gu re 5 .Fi gu re 6 .1
En do don tic fi les pla ced in two ca nals of the te eth 41, 42 and 43 Sli ka 5. Po sta vlja nje ka nal nih in stru me na ta u dva ka na la zu ba 41, 42 i 43 ra di di jag no sti ke Fi gu re 3. En do don tic fi les pla ced in two ca nals Sli ka 3. Po sta vlja nje ka nal nih in stru me na ta u dva ka na la ra di di jag no sti ke Fi gu re 4. Fi nal ob tu ra tion of two ro ot ca nals Sli ka 4. Ko nač no pu nje nje oba ka na la ko re na Fi nal ob tu ra tion of two ca nals in the lo wer right cen tral and la te ral in ci sors Sli ka 6. Ko nač no pu nje nje oba ka na la ko re na do njeg de snog cen tralnog i la te ral nog se ku ti ćaEndodontsko lečenje donjih frontalnih zuba sa višekanalnim sistemom Mirjana Vujašković 1 , Nikola Stojanović 2 , Goran Vujašković 3 Klinika za bolesti zuba i endodonciju, Stomatološki fakultet, Univerzitet u Beogradu, Beograd, Srbija; 2 Katedra za bolesti zuba i endodonciju, Medicinski fakultet, Univerzitet u Istočnom Sarajevu, Foča, Bosna i Hercegovina; 3 Institut za anatomiju, Stomatološki fakultet, Univerzitet u Beogradu, Beograd, Srbija