Pulp Revascularization of an Immature Permanent Tooth with Apical Periodontitis – A Case Report

The present case report analyzes the outcome of revascularization treatment 
 of an immature permanent tooth with necrotic pulp and apical periodontitis. 
 The canal was disinfected with copious irrigation and application of triple 
 antibiotic paste. After the disinfection protocol was completed, apical 
 bleeding was induced in the canal resulting in the formation of a blood clot. 
 An absorbable scaffold was placed over it followed by an adequate triple 
 coronal seal. After nine months follow-up, increased thickening of dentinal 
 walls with intact lamina dura and complete apical closure was reported 
 radiographically. Therefore, revascularization therapy could be recommended 
 as an alternative treatment option.


INTRODUCTION
Endodontic therapy is one of the most progressive as pects in modern dentistry.Significant advancements in debridement and obturation techniques have occurred in recent years.Consequently, successful treatment rates of 95% for teeth with irreversible pulpitis and 85% for necrotic teeth have been reported [1].
However, the treatment of an immature tooth with ne crotic pulp has always been a challenge in endodontics.It is difficult to obtain an appropriate apical seal in teeth with open apices using conventional endodontic treatment methods.Discontinued development of dentinal walls after pulp necrosis can also lead to weak root canal structure with thin dentinal walls which makes the tooth suscept ible to future fracture.Conventional technique such as multiplevisit apexification with calcium hydroxide and artificial barrier technique performed by placing Mineral Trioxide Aggregate (MTA) in the apical portion of the canal share the same disadvantage of not providing continuous root development which leads to fragile root structure [2].
Recently, there have been introduced better alternatives to conventional treatment of immature permanent teeth with periapical pathology.Procedures attempting to pre serve remained dental pulp and mesenchymal stem cells of apical papilla can result in canal revascularization and completion of root maturation [3,4].
Revascularization is regenerative treatment and bio logically based alternative approach to treat necrotic im mature teeth that in contrast to apexification and artificial barrier technique allows continuation of root develop ment [5].It is based on the concept that vital stem cells can differentiate into secondary odontoblasts, ultimately allowing dentin deposition [3].Survival of stem cells is aided by abundant blood supply to apical papilla, contrib uting to pulp revascularization [4].Even in luxated and avulsed tooth, revascularization is possible [6,7].Iwaya et al. [8] showed that a human immature permanent tooth with necrotic pulp and apical periodontitis/abscess after revascularization procedure can induce increased thick ness of the canal walls and continuous root development.
The current case report describes successful revascu larization treatment outcome of an immature permanent right maxillary central incisor with clinical and radio graphic signs of necrotic pulp and apical periodontitis.

CASE REPORT
A 17yearold boy was referred to the Department of Con servative Dentistry and Endodontics of the National Den tal College and Hospital, Dera Bassi for the evaluation of right maxillary central incisor with a history of trauma 8 years ago.Clinical examination revealed extensively carious right maxillary central incisor sensitive to percussion.Cold test and electric pulp test elicited no response (Figure 1).Periodontal status was normal (i.e probing depth < 3 mm) and the tooth showed no mobility.Radiographic evaluation revealed an immature open apex associated with radiolu cent periapical lesion (Figure 2).Right maxillary lateral in cisor was clinically sound and responded normally to cold and electric pulp test.No significant medical history was reported.Concluding diagnosis was pulpal necrosis with symptomatic chronic apical periodontitis and revascular ization was chosen as optimal treatment.
After obtaining an informed consent, a rubber dam was applied, remaining carious tooth structure removed and ac cess cavity prepared.No purulent exudates or hemorrhage was observed in the pulp chamber.The working length was determined.The canal was passively irrigated with 20 ml of 5.25 % NaOCl (Prime Dental Products Pvt.Ltd India).The apical opening was enlarged to 1.1 mm using 110 K instrument (Mani KFiles, Japan).After copious irrigation, the canal was dried with paper points and a creamy paste of equal proportion of ciprofloxacin, metronidazole and minocycline was prepared using sterile water as described by Windley et al. [11] and placed inside the canal with Kfile in anticlockwise motion.The access cavity was cleaned with sterile cotton pellet and restored temporarily with Cavit (3M ESPE, Deutschland GmbH, Germany) for a period of 2 weeks.The triple antibiotic paste was replaced again after 2 weeks for additional 2 weeks.
At the 5th week followup, the patient was asymptom atic, and no sensitivity to percussion and palpation was reported (Figure 3).The tooth was anesthetized with 2% lignocaine hydrochloride containing 1:200,000 adrena line (Astra Zeneca Pvt. Ltd.Bangalore, India).After rubber dam isolation, temporary restoration was removed.The canal was flushed with 10 ml of 5.25 % NaOCl and dried with paper points.Kfiles were used to induce bleeding in the canal by irritating periapical tissue.Bleeding was stopped at the level of 3 mm below cementenamel junc tion (CEJ) by applying pressure with a sterile saline soaked cotton pellet for 15 minutes so that the blood would clot at that level.After 15 minutes, an absorbable scaffold (Gel spon, Eucare Pharmaceuticals Pvt. Ltd.India) was gently placed over the blood clot.MTA (MTA Angelus Repara tive Cement, Angelus Ind. de.Prod.Odontologicos S/A, Brasil) was carefully placed against the scaffold followed by a wet cotton pellet and Cavit (Figure 4).
At the 6th week followup, the patient was asymptom atic, temporary restoration was removed and the tooth was restored with a glass ionomer base (GC Gold Label Glass    Ionomer, GC America Inc.) as a second sealing agent over MTA followed by a permanent bondedresin restoration (3M ESPE Adper Single Bond Adhesive, 3M ESPE Filtek Z250 XT Nanohybrid Universal Restorative 3M ESPE Dental Products, USA) in order to provide an adequate triple seal to prevent coronal leakage (Figures 5ab and 6).
The patient was scheduled for recall at 3 months, 6 months and 9 months and advised to call if he had pain or swelling.At the 3rd month recall, the patient was asymptomatic.The radiograph showed signs of healing with decreased size of periapical radiolucency and thickening of the root canal walls (Figure 7).At the 6th month recall, complete resolution of periapical radiolucency was evident radio graphically (Figure 8).Lamina dura was intact along the root surface.The pulp testing was inconclusive.At the 9th month recall, the patient was asymptomatic as well.Radiographically, increased thickening of dentinal walls with intact lamina dura and complete apical closure was reported (Figure 9).Pulp testing was still inconclusive.

DISCUSSION
The benefits of revascularization technique over conven tional methods include continuation of root development and strengthening of the remaining root structure.With an attempt to gain these benefits, in the present case re vascularization was chosen as a treatment option over other alternatives.Elimination of microorganisms and necrotic tissue from the root canal system is the key fac tor in successful revascularization.Studies have revealed that chlorhexidine irrigation might have cytotoxic effects on human cells [12] and interfere with the attachment of dental papilla stem cells to the root canal walls [13].Thus, in this case 5.25% sodium hypochlorite was used as irrigant.
Previous studies have pointed out different methods for disinfecting necrotic immature teeth in revascularization treatment including the use of triple antibiotic paste [6], calcium hydroxide [14] and formocresol [15].Hoshino et al. [16] and Sato et al. [17] in two separate in vitro studies used a mixture of metronidazole, ciprofloxacin and mino cycline against endodontic pathogens and were able to disinfect even deeper layers of dentin in infected teeth.An animal study done by Windley et al. [11] in 2005 revealed that triple antibiotic dressing placed in infected canals for 2 weeks resulted in bacteria free culture in 70% of cases.Based on these observations, triple antibiotic dressing was placed for 4 weeks in the root canal to achieve disinfection and encouraging results were obtained.
Instrumentation is contraindicated in revasculariza tion treatment because root dentin walls are extremely thin and any further instrumentation would make them weaker and more susceptible to future fractures.Also, the formation of smear layer could occlude dentinal tubules.The notion that successful regeneration depends on the race between new tissue and bacteria populating the pulp chamber is strengthened by the fact that the incidence of revascularization is enhanced if the apex shows radio graphic opening of more than 1.1 mm [6].Taking this into consideration, in the present case, apical opening was enlarged to more than 1.1 mm using 110 K instrument with the tip diameter of 1.1 mm to provide easy access of new tissue into the root canal system.
It is assumed that blood clot formed inside the disin fected empty space that contains platelet rich scaffold might be crucial for successful population and differentia tion of stem cells and ultimately root development [18].Thibodeau and Trope [19] demonstrated that root canals that had blood clot formation inside them after disinfec tion had better radiographic outcomes compared with those without blood clot.Therefore, in the present study, a blood clot was created in the canal after disinfection.One might assume that blood clot may break down and leave root canal space without scaffold where new tissue    should grow for regeneration [20].Therefore to avoid this loss of scaffold, an absorbable collagen scaffold was placed over the formed blood clot.This also provided a barrier against which MTA plug was condensed resulting in an effective triple coronal seal.The importance of bacteriatight coronal seal for suc cessful revascularization is welldocumented [6].Majority of reported studies have used double seal over the blood clot formed inside the canal, MTA and resinbonded res toration [6,19].Wang et al. [21] in an animal study on revascularization showed that a cemental bridge is formed beneath MTA in most cases, which might be the result of cementogenic and osteogenic properties of MTA.In addi tion, in the present case, glass ionomer base was placed as a second sealing agent over MTA, followed by a permanent coronal resinbonded restoration.Hence, successful out come may also be attributed to this effective coronal seal.
An interesting question is the nature of new tissue pro duced in the root canal space after this procedure.It has been shown that three types of tissue i.e. cementum like tissue along dentinal walls responsible for root cancel wall thickening, bone like tissue and periodontal ligament like tissue were generated after the treatment [21].We must acknowledge that vitality of pulp tissue was not known.In the present case blood supply was required for the root canal wall to become thicker and apex to close.New tissue within pulp space although not necessarily pulp, compris es not only blood vessels but also vital cells required to lay down new tissue.Since vital tissue inside the canal is not necessarily pulp tissue, the term regeneration may not be appropriate, therefore, preferred term is revascularization suggesting that blood supply in previously necrotic pulp space has been restored.
There has been a tremendous increase in our clinical tools (i.e.materials, instruments and medications) and knowledge in tissue engineering fields during the last dec ade.The question is no longer "Is regenerative endodontic procedure successful?"Instead, the important question we are facing is "What are the issues that must be addressed to develop safe and effective method to regenerate func tional pulpdentin complex?"Future research should focus on translational research models that emphasize keeping the tissue in its natural state instead of doing conventional endodontic treatment.However, more studies with long followups on this proposed technique will be valuable in finding reliable ways to successful treatment outcomes.

KRATAK SADRŽAJ
U ovom pri ka zu ana li zi ra na je me to da re va sku la ri za ci je u le če nju stal nih zu ba sa ne za vr še nim ra stom ko re na i api kal nim pe ri o donti ti som.Dez in fek ci ja ka na la po stig nu ta je obil nom iri ga ci jom i pri me nom in tra ka nal ne pa ste sa tri an ti bi o ti ka.Na kon dez in fek ci je iza zva no je api kal no kr va re nje ko je je do ve lo do stva ra nja krv nog ugru ška u ka na lu.Po tom je po sta vlje na re sorp tiv na mre ži ca pre ko ugru ška, kao i tro sloj ni is pun.Na kon de vet me se ci na rend gen skom snim ku uoče ni su za de blja nje den tin skih zi do va s in takt nom la mi nom du rom i kom plet no za tva ra nje apek sa.Te ra pi ja re va sku la ri za ci jom mo že se pre po ru či ti kao al ter na tiv no re še nje u le če nju stal nih zu ba sa ne za vr še nim ra stom ko re na i api kal nim pe ri o don ti ti som.Ključ ne re či: apek si fi ka ci ja; teh ni ka ve štač ke ba ri je re; re va sku la ri za ci ja; ma tič ne će li je; pa sta sa tri an ti bi o ti ka UVOD En do dont sko le če nje je jed no od naj na pred ni jih aspe ka ta sa vre me ne sto ma to lo gi je.Po sled njih ne ko li ko go di na do šlo je do zna čaj nog na pret ka u dez in fek ci ji i op tu ra ci ji ka na la ko re na zu ba.Ta ko je sa da pro ce nat uspe ha en do dont skog le če nja oko 95% za zu be sa ire ver zi bil nim pul pi ti som i 85% za zu be sa ne kro tič nom pul pom [1].
Te ra pi ja stal nih zu ba sa ne za vr še nim ra stom ko re na i ne kro tič nom pul pom je od u vek bi la iza zov u en do don ci ji.Kod zu ba s otvo re nim apek som ne do la zi uvek do uspe šnog za tva ra nja apek sa kon ven ci o nal nim me to da ma le če nja.Pre ki nut rast ko re na na kon ne kro ze pul pe mo že do ve sti do sla blje nja struk tu re zi da ka na la ko re na, gde tan ki den tin ski zi do vi či ne zub pod lo žan lo mlje nju.Kon ven ci o nal ne teh ni ke, kao što su apek si fi ka ci ja ko re na po mo ću kal ci jumhi drok si da ili teh ni ka ve štač ke ba ri je re po mo ću mi ne ral nog tri ok si da (MTA), ne pod sti ču na sta va k ra sta ko re na, što do vo di do sla blje nja nje go ve struk tu re [2].
Ne dav no su uve de ne no ve me to de kao al ter na ti ve kon ven ci o nal nom le če nju stal nih zu ba sa ne za vr še nim ra stom ko re na i pe ri a pi kal nom pa to lo gi jom.Ove me to de, či ji je cilj oču va nje pre o sta le zub ne pul pe i me zen hi mal nih ma tič nih će li ja iz api kal ne pa pi le, mo gu do ve sti do re va sku la ri za ci je ka na la i za vr šet ka ra sta ko re na zu ba [3,4].
Re va sku la ri za ci ja je re ge ne ra tiv na me to da ko ja ima bi o lo ški pri stup u le če nju stal nih zu ba sa ne za vr še nim ra stom ko re na i ne kro tič nom pul pom i, za raz li ku od apek si fi ka ci je ko re na i teh ni ke ve štač ke ba ri je re, omo gu ća va za vr še tak ra sta ko re na [5].Ona se te me lji na kon cep tu da se vi tal ne ma tič ne će li je mo gu tran sfor mi sa ti u se kun dar ne odon to bla ste i sin te ti sa ti den tin [3].Op sta nak ma tič nih će li ja pot po mog nut je do brom va sku la ri za ci jom api kal ne pa pi le ko ja do pri no si re va sku la ri za ci ji pul pe [4].Re va sku la ri za ci ja je mo gu ća čak i kod luk si ra nih ili avul zi ra nih zu ba [6,7].Iva ja (Iwaya) i sa rad ni ci [8] su po ka za li da je kod stal nih zu ba sa ne za vr še nim ra stom ko re na i ne kro tič nom pul pom i api kal nim pe ri o don ti ti som/ap sce som na kon po stup ka re va sku la ri za ci je do šlo do po ve ća nja de blji ne zi da ka na la i za vr šet ka ra sta ko re na.Dru gi auto ri su ta ko đe do šli do slič nih za klju ča ka [6,9,10].
Ovaj pri kaz slu ča ja opi su je us pe šan is hod re va sku la ri za ci je stal nog de snog mak si lar nog cen tral nog se ku ti ća sa ne za vr še nim ra stom ko re na i kli nič kim i ra di o lo škim zna ci ma ne kro tič ne pul pe i api kal nog pe ri o don ti ti sa.

PRIKAZ SLUČAJA
Se dam na e sto go di šnji mla dić je upu ćen na Kli ni ku za kon zer va tiv nu sto ma to lo gi ju i en do don ci ju Na ci o nal nog sto ma to lo škog fa kul te ta i bol ni ce u De ra Ba si zbog de snog mak si lar nog cen tral nog se ku ti ća ko ji je bio po vre đen osam go di na ra ni je.Kli nič kim pre gle dom je utvr đe na ve li ka ka ri je sna le zi ja na tom zu bu.Zub je bio ose tljiv na per ku si ju, dok na hlad no i na elek trič ni test vi ta li te ta ni je re a go vao (Sli ka 1).Pe ri o don tal ni sta tus zu ba bio je nor ma lan (du bi na gin gi val nog sul ku sa je bi la ma nja od 3 mm) i zub ni je bio po kre tljiv.Rend gen ski sni mak je po ka zao otvo re ni vrh ko re na po ve zan sa ra di o lu scent nom pe ri a pi kal nom le zi jom (Sli ka 2).De sni la te ral ni se ku tić je bio zdrav i po ka zao je nor mal nu re ak ci ju na hlad no i elek trič ni test vi ta li te ta.U op štoj anam ne zi ni je bi lo zna čaj nih po da ta ka.Ko nač na di jag no za je gla si la "ne kro za pul pe sa simp to mat skim hro nič nim api kal nim pe ri o don ti ti som", a me to da re va sku la ri za ci je je iza bra na kao op ti ma lan na čin te ra pi je.
Na kon pri stan ka pa ci jen ta na in ter ven ci ju, po sta vljen je ko fer dam, uklo njen ka ri jes zu ba i is pre pa ri san pri stup ni ka vi tet.U ko mo ri pul pe ni je bi lo gnoj nog ili he mo ra gič nog sa dr ža ja.Od re đe na je rad na du ži na.Ka nal je pa siv no is pran sa 20 ml 5,25% Na OCl (Pri me Den tal Pro ducts Pvt.Ltd, In di ja).Api kal ni otvor je pro ši ren do 1,1 mm po mo ću Ke ro vog (Ke rr) in stru men ta ve li či ne 110 (Ma ni K-Fi les, Ja pan).Na kon obil nog is pi ra nja ka nal je osu šen pa pir nim po e ni ma, a pri pre mlje na pa sta sa jed na kim od no som ci pro flok sa ci na, me tro ni da zo la i mi no ci kli na u ste ril noj vo di, kao što su opi sa li Vin dli (Win dley) i sa rad ni ci [11], une ta u ka nal po mo ću Ke ro vog in stru men ta ro ta ci jom u obr nu tom sme ru od sme ra kre ta nja ka zalj ki.Pri stup ni ka vi tet je oči šćen ste ril nom va ti com i za tvo ren pri vre me no Ca vitom (3M ESPE, De utschland GmbH, Ne mač ka) to kom dve ne de lje.An ti bi ot ska pa sta sa tri an ti bi o ti ka za me nje na je po sle dve ne de lje i osta vlje na u ka na lu još dve ne de lje.
Na pre gle du po sle pet ne de lja pa ci jent je bio bez simp to ma, a zub neo se tljiv na pal pa ci ju i per ku si ju (Sli ka 3).Na kon pri me ne ane ste zi je dvo pro cent nim lig no kainhi dro hlo ri dom s adre na li nom u od no su 1:200.000(Astra Ze ne ca Pvt. Ltd., Ban ga lor, In di ja), po sta vljen je ko fer dam i uklo njen pri vre me ni is pun.Ka nal je is pran sa 10 ml 5,25% Na OCl i osu šen pa pir nim po e ni ma.Ke ro vim in stru men ti ma je izi ri ti ran pe ri a peks, ko ji je do veo do kr va re nja u ka na lu.Kr va re nje je za u sta vlje no 3 mm is pod gleđ noce ment ne gra ni ce pri ti skom po mo ću ste ril ne va ti ce na to plje ne fi zi o lo škim ras tvo rom to kom 15 mi nu ta.Po sle 15 mi nu ta ap sorp tiv na mre ži ca (Gel spon, Euca re Pharma ce u ti cals Pvt. Ltd., In di ja) je po sta vlje na na krv ni ugru šak.Pre ko ugru ška su po sta vlje ni MTA (MTA-An ge lus Re pa ra ti ve Ce ment, An ge lus Ind. de.Prod.Odon to lo gi cos S/A, Bra zil), vla žna ste ril na ku gli ca va te i Ca vit (Sli ka 4).
Na pre gle du po sle šest ne de lja pa ci jent ni je imao simp to ma.Pri vre me ni is pun je uklo njen, a po sta vljen je gla sjo no merce ment (GC Gold La bel Glass Iono mer, GC Ame ri ca Inc., SAD) pre ko MTA, a po tom i is pun na ba zi smo le (3M ESPE Ad per Sin gle Bond Ad he si ve, 3M ESPE Fil tek Z250 XT Na nohybrid Uni ver sal Re sto ra ti ve -3M ESPE Den tal Pro ducts, SAD).Po mo ću ova kvog tro sloj nog is pu na po stig nu to je do bro ko ro nar no zap ti va nje (Sli ke 5ab i 6).Pa ci jen tu je za ka zan kon trol ni pre gled za tri me se ca, po tom za šest i de vet me se ci, a dat mu je sa vet da se ja vi ako u me đu vre me nu do đe do ne kih pro me na, bo la ili oto ka.
Na kon trol nom pre gle du po sle tri me se ca pa ci jent je i da lje bio bez simp to ma.Rend gen ski sni mak je po ka zao zna ko ve ozdra vlje nja sa sma nje nom ve li či nom pe ri a pi kal nog ra sve tlje nja, kao i za de blja nje zi do va ka na la ko re na (Sli ka 7).Po sle šest me se ci, do šlo je do pot pu nog ne sta ja nja pe ri a pi kal nog ra sve tlje nja (Sli ka 8).La mi na du ra je bi la in takt na oko či ta vog ko re na.Vi ta li tet pul pe je bio ne si gu ran.Po sle de vet me se ci ta ko đe ni je bi lo simp to ma.Ra di o lo ški na laz je po ka zao za de blja ne den tin ske zi do ve ka na la ko re na s in takt nom la mi nom du rom i pot pu no za tva ra nje apek sa (Sli ka 9).Test vi ta li te ta je i da lje bio ne si gu ran.

DISKUSIJA
Pred no sti me to de re va sku la ri za ci je nad kon ven ci o nal nim me to da ma uklju ču ju za vr še tak ra sta i oja ča nje struk tu re ko re na.Zbog to ga je u ovom pri ka zu slu ča ja do ne ta od lu ka da se pri me ni me to da re va sku la ri za ci je.Eli mi na ci ja mi kro or ga ni za ma i ne kro tič nog tki va iz ka na la ko re na je va žan uslov da bi se po sti gao uspeh re va sku la ri za ci je.S ob zi rom na to da je po ka za no da hlor hek si din mo že ima ti ci to tok sič ni efe kat na ljud ske će li je [12] i ome ta ti pri poj ma tič nih će li ja zub ne pa pi le na zi do ve ka na la ko re na [13], u ovom slu ča ju je za is pi ra nje ka na la ko ri šćen na tri jumhi po hlo rit od 5,25%.
U ra ni jim stu di ja ma su ana li zi ra ne raz li či te me to de za dez in fek ci ju ka na la ko re na stal nih zu ba sa ne za vr še nim ra stom ko re na i ne kro tič nom pul pom to kom pri me ne me to de re va sku la ri za ci je, kao što su pa sta sa tri an ti bi o ti ka [6], kal ci jumhi drok sid [14] i for mo kre zol [15].Ho ši no (Hos hi no) i sa rad ni ci [16] i Sa to (Sa to) i sa rad ni ci [17] su u dve ne za vi sne stu di je in vi tro ko ri sti li me ša vi nu me tro ni da zo la, ci pro flok sa ci na i mi no ci kli na pro tiv en do dont skih pa to ge na i us pe li da dez in fi ku ju i du blje slo je ve den ti na u in fi ci ra nim zu bi ma.Stu di ja na ži vo ti nja ma ko ju su spro ve li Vin dli i sa rad ni ci [11] 2005. go di ne po ka za la je da pri me na pa ste sa tri an ti bi o ti ka to kom dve ne de lje mo že do ve sti do eli mi na ci je bak te ri ja u 70% slu ča je va.Na osno vu te stu di je, pa sta sa tri an ti bi o ti ka je une se na u ka nal i po sle če ti ri ne de lje su do bi je ni do bri re zul ta ti.
Me ha nič ka ob ra da ka na la je kon tra in di ko va na to kom pri me ne me to de re va sku la ri za ci je, jer su den tin ski zi do vi ka na la ko re na iz u zet no tan ki, ta ko da bi do dat no me ha nič ko ukla nja nje den ti na osla bi lo zi do ve a zub po stao ose tljiv na lo mlje nje.Ta ko đe, raz ma zni sloj bi mo gao za tvo ri ti den tin ske ka na li će.Te o ri ja da uspeh re ge ne ra ci je za vi si od tr ke iz me đu no vog tki va i bak te ri ja u na se lja va nju ko mo re pul pe do ka za na je i či nje ni com da je mo gu će po sti ći bo lje re zul ta te ako je apeks ko re na otvo ren vi še od 1,1 mm [6].Uzi ma ju ći to u ob zir, u ovom slu ča ju api kal ni otvor je pro ši ren vi še od 1,1 mm po mo ću Ke ro vog in stru men ta ve li či ne 110, či ji vrh ima ve li či nu upra vo 1,1 mm, da bi se omo gu ći lo pro ra sta nje no vog tki va u ka nal ko re na.
Pret po sta vlja se da je krv ni ugru šak bo gat trom bo ci ti ma ko ji je for mi ran u dez in fi ko va nom pra znom pro sto ru osno va u ko joj do la zi do pro ra sta nja i di fe ren ci ra nja ma tič nih će li ja i ra sta ko re na [18].Ti bo do (Thi bo de au) i Trop (Tro pe) [19] su po ka za li da su ko re no vi u či jim je ka na li ma do šlo do for mi ra nja krv nih ugru ša ka na kon dez in fek ci je ima li bo lje re zul ta te (ra di o lo ški) u po re đe nju s oni ma bez krv nog ugru ška.Za to je u ovom pri ka zu slu ča ja na kon dez in fek ci je for mi ran krv ni ugru šak u ka na lu.Mo gu će je ta ko đe da do đe do ras pa da nja krv nog ugru ška i da osta ne pra zan pro stor ta mo gde bi tre ba lo do ći do pro ra sta nja no vog tki va [20].Da bi se iz be gao gu bi tak ove osno ve, pre ko krv nog ugru ška je po sta vljen re sorp tiv ni ko la gen.On je pred sta vljao i ba ri je ru pre ma MTA i do pri neo uspe šnom tro sloj nom ko ro nar nom zap ti va nju.
Zna čaj ko ro nar nog zap ti va nja i eli mi na ci ja bak te ri ja za us peh re va sku la ri za ci je su do bro pro u če ni [6].U ve ći ni stu di ja po sta vlje na su dva slo ja pre ko krv nog ugru ška for mi ra nog unu tar ka na la, MTA i is pun na ba zi smo le [6,19].Vang (Wang) i sa rad ni ci [21] su u stu di ji na ži vo ti nja ma po ka za li da u ve ći ni slu ča je va do la zi do for mi ra nja ce ment nog mo sta is pod MTA, što bi mo gao bi ti re zul tat ce men to ge nog i oste o ge nog svoj stva MTA.Kod pri ka za nog pa ci jen ta pre ko MTA je po sta vljen sloj gla sjo no merce men ta, a po tom i is pun na ba zi smo le.Ta ko se uspeh le če nja mo že pri pi sa ti i do brom ko ro nar nom zap ti va nju.
Za ni mlji vo pi ta nje je i pri ro da no vog tki va na sta log u ka na lu ko re na po sle pri me ne me to de re ge ne ra ci je.Po ka za ne su tri vr ste tki va: tki vo na lik ce men tu ko je je od go vor no za za de blja nje zi do va ko re na, tki vo na lik ko šta nom i tki vo na lik pe ri o don tal nom li ga men tu [21].Vi ta li tet pul pe se ni je mo gao sa si gur no šću utvr di ti.U sva kom slu ča ju, da bi do šlo do za de blja nja zi do va ko re na i za tva ra nja apek sa, bio je po tre ban do tok kr vi.No vo tki vo u ka na lu, iako ne nu žno pulp no tki vo, sa dr ži krv ne su do ve i će li je po treb ne za sin te zu no vog tki va.S ob zi rom na to da tki vo u ka na lu mo žda i ni je pulp no tki vo, ter min "re ge ne ra ci ja" ni je pot pu no ta čan.Bo lji iz raz bi bio "re va sku la ri za ci ja", ko ji uka zu je na to da je po no vo us po sta vljen do tok kr vi u pro stor ne kro tič ne pul pe.
U po sled njoj de ce ni ji do šlo je do ve li kog na pret ka u en do dont skim "ala ti ma" (ma te ri ja li, in stru men ti i le ko vi) i zna nju o in že nje rin gu tki va.Vi še se ne po sta vlja pi ta nje da li re ge ne ra tiv ni po stu pak mo že bi ti us pe šan.Ume sto to ga va žni je je pi ta ti ko ji su to pro ble mi ko ji se mo ra ju re ši ti da bi se po sti gla si gur na i efek tiv na re ge ne ra ci ja funk ci o nal nog pul poden tin skog kom plek sa.Bu du ća is tra ži va nja bi tre ba lo da se usme re na me to de či ji je cilj oču va nje tki va u svom pri rod nom sta nju ume sto kon ven ci o nal nog en do dont skog le če nja.Ta ko đe, vi še stu di ja ko je bi pri me nu ove pred lo že ne me to de pra ti le kod pa ci je na ta to kom du žeg pe ri o da do pri ne le bi pro na la sku po u zda nih na či na za po sti za nje do brog uspe ha le če nja.

Figure 5 .Figure 1 .
Figure 5. Placement of triple coronal seal of MTA, glass ionomer cement and bonded-resin restoration with respect to maxillary right central incisor (a -buccal view; b -palatal view) Sli ka 5. Po sta vljen tro stru ki is pun od MTA, gla sjo no mer-ce men ta i is pu na na ba zi smo le na gor njem de snom cen tral nom se ku ti ću (a -po gled sa la bi jal ne stra ne; b -po gled sa pa la ti nal ne stra ne)

Figure 2 .
Figure 2. Maxillary right central incisor with open apex.Large periapical radiolucency was associated with both maxillary right central and lateral incisor.Sli ka 2. Gor nji de sni cen tral ni se ku tić s otvo re nim apek som.Uočeno je ve li ko pe ri a pi kal no ra sve tlje nje po ve za no s gor njim de snim cen tral nim i la te ral nim se ku ti ćem.

Figure 3 .
Figure 3. Radiograph 30 days after the placement of triple antibiotic paste Sli ka 3. Rend gen ski na laz 30 da na na kon pri me ne pa ste sa tri an tibi o ti ka u ka nal ko re na

Figure 4 .
Figure 4. Radiograph confirming the placement of MTA approximately 3 mm below the CEJ Sli ka 4. Rend gen ska po tvr da posta vlje nog MTA ot pri li ke 3 mm is pod ce ment no gleđ ne gra ni ce

Figure 6 .
Figure 6.Radiograph showing effective triple coronal seal of MTA, glass ionomer cement and bonded-resin restoration with respect to maxillary right central incisor Sli ka 6. Rend gen ski sni mak po ka zu je tro stru ki is pun od MTA, gla sjo no mer-ce men ta i is pu na na ba zi smo le na gor njem de snom cen tral nom se ku ti ću.

Figure 7 .
Figure 7. Postoperative radiograph after 3 months.Decreased size of periapical radiolucency and thickening of the root canal walls was observed.Sli ka 7. Po sto pe ra ci o ni rend gen ski na laz na kon tri me se ca.Uočeni su sma nje nje ve li či ne pe ri a pi kal nog ra sve tlje nja i za de blja nje zi do va ka na la ko re na.

Figure 8 .
Figure 8. Postoperative radiograph after 6 months.Complete resolution of periapical radiolucency was noted.Sli ka 8. Po sto pe ra ci o ni rend gen ski na laz na kon šest me se ci.Pe ri api kal no ra sve tlje nje je pot pu no ne sta lo.

Figure 9 .
Figure 9. Postoperative radiograph after 9 months.Increased thickening of dentinal walls with intact lamina dura and complete apical closure was observed.Sli ka 9. Po sto pe ra ci o ni rend gen ski na laz na kon de vet me se ci.Uočeni su za de blja nje den tin skih zi do va, in takt na la mi na du ra i pot pu no za tva ra nje apek sa.