http://dx.doi.org/10.5933/jkapd.2015.42.2.197 ISSN (print) 1226-8496 ISSN (online) 2288-3819 The Scope of Regenerative Endodontics on Open-Apices in Young Permanent Teeth Yongbum Cho Department of Conservative Dentistry, School of Dentistry, Dankook University, Cheonan Korea Abstract Numerous challenges in treating permanent dentition are encountered, especially in treating immature teeth with pulp necrosis. Historically, calcium hydroxide application during long periods of time was used to induce the formation of a calcific barrier across the open apex. In 2004, a new treatment modality for the management of the open apex was introduced. This treatment was named as revascularization and gained acceptance among dentists. The protocol was different from the traditional apexification techniques in that the canal was irrigated and disinfected with a combination of three antibiotics (ciprofloxacin, metronidazole and minocycline). At the next appointment, bleeding was induced and the canal was sealed with MTA. Successful regenerative endodontic treatment of necrotic immature permanent teeth can provide continued root development, increased thickness in the dentinal walls and apical closure. These developments of a functional pulp-dentin complex have a promising impact on retaining the natural teeth, the goal of the dental health care. Key words : Apexification, Immature teeth, Regenerative Endodontics, Revascularization, Calcium hydroxide, MTA Ⅰ. 서론일반적으로치근첨형성이덜된미성숙영구치에치수침범이있다면, 기존의근관형성및근관충전법은한계가있기때문에, 치수의생활력에따라먼저 apexogenesis( 근첨유도술 ) 또는 apexification( 근첨형성술 ) 을시도하여인위적인치근첨형성을얻고자한다. 이와같이치근첨형성이되지않은치아가심한우식이나외상에의해치수감염또는괴사될수있으며, 예로 Dens Evaginatus의경우에도미성숙치근의치수괴사를흔히볼수있다. 개방성치근을갖는미완성치근에서의치수괴사는환자및치과의로하여금처치곤란한문제를종종야기하기도하는데, 그동안재료나방법에따라수산화칼슘을사용한근첨형성술, 또는 MTA(mineral trioxide aggregate) 를이용 한근첨형성술을시행하였다. 2004년, Banchs와 Trope은개방성치근을치료할때 revascularization 이라는새임상치료사례를발표하였다 1). 새로제시된방법이기존의근첨형성술과다른것은, 근관을 NaOCl과 CHX(Chlorhexidine), 그리고세가지항생제 (ciprofloxacin, metronidazole, minocycline) 를혼합한호제 (paste) 로근관을소독하며, 그다음약속때항생제호제를제거하고근관에인위적출혈을유도한다음, mineral trioxide aggregate(mta) 로봉하고 MTA가경화된후접착성수복물을적용한다는점이다. 이러한새로운패러다임은치근길이가짧고근관의상아질벽이얇으며치근단병소를갖고있어동시에여러문제를해결해야하는도전적인양상을지닌미성숙된치근에적합하다. Corresponding author : Yongbum Cho Department of Conservative Dentistry, School of Dentistry, Dankook University, 119 Dandae-ro, Dongnam-gu, Cheonan, 330-714, Korea Tel: +82-41-550-0242 / Fax: +82-41-550-0243 / E-mail: raindrop@dku.edu Received May 18, 2015 / Revised May 19, 2015 / Accepted May 19, 2015 197
Ⅱ. 본론주로외상이나심한우식으로인하여치수가감염될경우미성숙영구치 (immature permanent teeth) 가생활력을잃을 (non-vital) 수있다. 이경우근첨형성술 (apexification) 이오랫동안치아를유지, 보존하는가장일반적인수단으로애용되어왔으며, 이는개방된치근첨에걸쳐 calcific barrier를형성하게끔근관과치근단조직내에환경을조성해주는술식이다. 치수괴사를동반한미성숙치아의근첨형성을유도하기위해, 근관내에가타퍼차와같은충전재를적용하기전에수산화칼슘을이용하는치료가보편화되었는데 (Fig. 1), 1966년 Frank 가언급한것처럼수산화칼슘 [Calcium hydroxide; Ca(OH)2] 이미성숙된무수치 (pulpless tooth) 의생리적인폐쇄를유도할수있다고보고한이래, 가장널리애용되어왔던재료이자술식이었다 2). 수산화칼슘근첨형성술의성공률은약 95% 정도로알려져있지만아직몇가지문제가있는데 ; calcific barrier의형성을예측하기어렵고또한그기간이 3~24 개월로오래걸리며, 수산화칼슘을다시적용하기위해다수의내원이필요하다는것이다 3). Andreasen과 Rosenberg는수산화칼슘을근관내에수 개월이상적용할경우고유의흡습성과단백질을분해하는성질때문에상아질의기계적성질을취약하게할수있다고보고하였다 4). 이외에 calcific barrier가형성된다음, 수산화칼슘호제를제거하고근관을가타퍼차와같은영구충전재로충전후수복하여야하는데, 실제로근관에서이를완전히제거하는것은거의불가능하기때문에잔존호제가 ZOE 계통의실러와반응하여미세누출이나재료간의부실한결합을야기할수있다 5). 이와같은문제로인해기존의수산화칼슘을이용한근첨형성술에변화가있었는데, 그중하나가 MTA를인공적차폐로사용하는것이다 6). MTA 근첨형성술은수산화칼슘을이용한 apical barrier의형성을기다리지않고치근단부에직접 MTA를적용시켜직접적인경조직의형성을기대하기때문에치료시간을단축하며양호한치근단치유를보장한다고하였다 7,8). 미국근관치료학회 (AAE) 에서는언급한 revascularization 및 pulpal regeneration을 Regenerative Endodontics 라하여, 공식견해 (Position Statement) 는 상아질과치근, 그리고치수-상아복합체의세포를포함한손상된치아구조를생리적으로대체하려고고안된생물학적인술식 이라정의하고있다. 다시말하면이것은조직공학의개념에기초를두어근관을건강한상태로회복시켜치근및주위조직의지속적인발달을 A B C D Fig 1. (A) Panoramic radiograph showing an open apex with a periradicular radiolucency of a tooth #45. (B) The working length was measured, and the canal was cleaned and shaped with 5.25% NaOCl. (C) After calcium hydroxide paste was introduced, the apical lesion was resolved. (D) 4-months radiograph showing the formation of apical barrier across the open apex. The canal was filled with a warm gutta-percha injection technique. 198
A B Fig 2. (A) Immature root apex with a necrotic infected root canal with apical periodontitis. The canal was irrigated with 1.52% NaOCl and tri-antibiotic paste. After 3 weeks, the antibiotics was removed and the blood clot was brought in the canal and the canal was filled with MTA (B) At 15 months, the patient is asymptomatic and apical healing is obvious with remarkable lengthening of the root. 꾀하려는것이다 (Fig. 2). 이를근거로기존의근첨형성술또는 apical barrier를사용하는것과다르게괴사된미성숙영구치의재생근관치료를할때에는지속적인치근의발달, 상아질벽두께의증가및개방된치근첨의폐쇄를예견, 기대할수있다 9). 재혈관화치료 (Revascularization treatment) 는세균이없는근관내에적절한 3차원적 scaffold와 stem/progenitor cell 이존재하고세균이들어가지않게밀봉이되면 devitalized, uninfected, avulsed, immature permanent teeth에서조직의치유가일어날수있다는가정에근거하고있다 1,10). 이론적으로는 periodontal blood supply에근접해있는 stem cells of the apical papilla (SCAP) 이치근단감염에도살아남아상아질을형성하는세포인 odontoblast-like한세포를형성한다고여겨진다 11,19). 이를조직공학 (tissue engineering) 으로볼때, 정상적으로기능하는세포나조직또는기관을재생하기위해서는줄기세포 (stem cell), 조직공학용뼈대또는비계 (scaffolds), 성장인자 (growth factors) 와같은세가지의주된기본요소가있어야한다. 최근의 regenerative endodontic procedures(reps) 는근관내의비계를제공하기위해상아질이나혈병또는 platelet-rich plasma(prp) 을이용한다. REPs를시행하기위해 3가지의고려사항은 1) 근관계의철저한소독, 2) Scaffold의형성, 3) 치관부의밀폐이다. 1) 근관계의철저한소독근관계를소독할때가장널리사용되는것은 NaOCl(sodium hypochlorite; 차아염소산나트륨 ) 이며, chlorhexidine 또는수산화칼슘이나항생제의호제이다. NaOCl은배양세균의약 40-60% 까지감소시키는것으로알려져있으며 12) 첫내원에 20 ml/canal이추천되지만, 고농도의 NaOCl은상아질표면에 stem cell이부착하는것을막고또 SCAP에독성을나타내기에저농도를사용하기를권한다. 항생제를사용하여근관을소독하는경우, 2001년 Iwaya 등 은 metronidazole과 cirprofloxacin의혼합호제를사용하여성공적인 revascularization을처음으로보고하였고 10), ciprofloxacin, metronidazole, minocycline을 1:1:1로만든 triple antibiotic paste가성공적으로사용된이래 1) 널리사용되고있다. Minocycline이함유된 triple antibiotic paste는상아질전체에스며들수있어근관깊은부위까지효과적으로소독할수있음이알려졌다 13). 하지만 minocycline 사용과관련한치아의변색이보고되었으며, 이에대해호제를적용하기전에 dentin bonding agent를깔아최소화하기를주장하였다 14). 또한 Chuensombat에의하면 triple antibiotic paste를사용할때는 0.39 mg/ml의농도가가장좋다고하였는데이농도에서괴사된치아에서분리된세균을효과적으로제거할수있으면서도세포독성또한적기때문이라고하였다 15). 2) Scaffold 의형성 Scaffold는세포와혈관계의성장과발육에필요한 틀 (framework) 을제공해준다. Scaffold를재건, 축조하는것은보통 2차내원에시작하며근관내소독후약 2주와 4주사이에시행한다. 만일감염의증세가지속된다면항생제를이용한추가적인약속을고려할수있다. Scaffold를만드는법은미리구부려서소독한 #20 K-file을치근단공약 2 mm를넘게기구조작하여, 백악-법랑경계부까지혈액으로차게하는것이다 16). 3) 치관부의밀폐근관내에 scaffold가형성되고나면세균이들어가지못하게밀폐하는것이중요하며, MTA가현재로써는 REPs에서치관부를밀폐하는데가장신뢰할만한재료이다 1). MTA는혈액이있는상황에서도경화할수있는 bioceramic이며, 일단경화되면세균침투에대한강한저항성을나타낸다 17). MTA가과다하게충전되는것을방지하기위해 CollaPlug TM 나 CollaCote TM 와같은재료를사용할수도있다 18). 199
Ⅲ. 임상적고려사항 2015년에권고하는 REPs의임상적고려사항은다음과같다 9). 치료대상은치수가괴사되었으며, 미성숙치근첨을가진치아로, 환자의협조가좋고, 환자가이술식에필요한약제나항생제에과민반응이없을경우에해당한다. 첫째날, 1. 마취후러버댐으로격리한다음, 근관와동을형성한다. 2. 치근단조직으로세척액이유출되는것을최소화하기위해주사침의끝이막히고측벽이개방된 (closed end and side-vented needle) 주사침이나 EndoVac TM 을사용하여 NaOCl 용액 20 ml로세척한다. 이때치근단조직에남아있는 stem cell에대한세포독성을최소화하기위해, 근관당 1.5% NaOCl 용액약 20 ml를 5분간세척하고생리식염수나 EDTA 용액 20 ml를다시 5분에걸쳐사용하되, 세척할때주사침은치근첨에서 1 mm 떨어진곳에위치시킨다. 3. 근관을건조시킨다음, 수산화칼슘제재나, 저농도의 triple antibiotic 호제를적용한다. 3중항생제를사용할경우변색을최소화하기위해치수강을 dentin bonding agent로차단하는것을고려해야하며, ciprofloxacin; metronidazole; minocycline을 1:1:1의비율로혼합하되최종적으로 0.1 mg/ml의농도가되도록한다음, 주사기를이용하여근관에적용한다. 이때주의할것은치관부의변색을최소화하기위해, CEJ 하방에위치하게하는것이다. 4. Cavit TM, IRM TM, glass ionomer나다른재료로약 3-4 mm 정도가봉한다음, 약 1-4 주후재내원하게한다. 둘째날 ( 첫째약속 1-4 주후 ) 1. 지속적인감염의징후 (sign/symptom) 가있는지평가한다. 2. 혈관수축제가없는 3% mepivacaine으로마취한다음, 러버댐으로격리한다. 3. 20 ml의 EDTA로부드럽게세척한다음근관을건조시킨다. 4. 소독된 file 등으로치근단공약 2 mm 넘어 over-instrumentation을함으로써인위적인출혈을유도하여 CEJ까지차도록한다. 이때 PRP(platelet rich plasma), PRF(platelet rich fibrin) 또는 AFM(autologous fibrin matrix) 를사용하여혈병을형성하여도무방하다. 이때주의할것은상방에수복재가 3-4 mm 두께로적용될공간을확보하는것이다. 5. 필요하다면 Collaplug TM, Collacote TM, CollaTape TM 과같은흡수성 matrix를혈병위에적용하고복조제로 white MTA를적용한다. 6. 복조제위에 glass ionomer를 3-4 mm 적용후, 40초간광중합한다. MTA로인한변색의우려가있다면, RMGI 나 Biodentine 으로대체할수있다. 임상적 REPs 에서고려해야할사항들은다음과같다. 1. 청소년기환자가성공율이높다. 2. 미성숙근첨을가진치아의치수가괴사된경우를그대상으로한다. 3. 상아질벽에대한기구조작을최소화하거나하지않는다. 4. 근관내약제를적용하고 5. 근관내혈병또는단백질 scaffold( 비계 ) 를형성한다. 6. 치관부를효과적으로봉인하여야한다. 어떤치료를시행하든지실패를염두해두어야하기에, REPs를시작하기전에반드시환자에대한사전교육이있어야한다. 2회이상의내원이필요하며또한임상적인결과를평가하기위해 follow-up이필요하다는것을주지시킨다. 주기적인관찰에서중점을두고평가할사항은 1. 치아의증상이소실되고정상적기능을하여야하고, 2. 방사선사진상 6-12 개월사이에는치근단병소가소실되고치근의상아질벽의두께가증가하는것이보여야하며, 12-24 개월사이에는상아질벽두께와함께치근의길이가증가하여야한다. 만일동통이나연조직의종창또는방사선사진상에서치근단병소의크기가증가한다면이는실패로간주하고 MTA를이용한인공적인치근단 barrier를형성해주거나발치와같은다른치료를고려해야한다. Ⅳ. 결론일반적으로구강내에치관부의맹출은완료되었으나치근첨이미완성인경우, 다양한원인에의해치수감염및치수괴사를보이는경우가있다. 치아를발치하지않고구강내에잔존시키려는노력은쉽지않은데, 완성되지않은치근및근관은근관벽이얇아근관형성및세정이곤란하며, 치근첨또한완전히형성되지않고벌어져있는나팔총모양 (blunderbuss shape) 이기에근관충전이불가능하다. 또한치료후에도파절의위험이높기때문에이를보존, 유지하는것은임상가의높은치료가치를필요로한다. 일반적으로시행되고있는수산화칼슘을이용한치근첨형성술은높은성공율과함께임상가들에게널리알려진치료법이다. 이또한치수괴사및치근단병소를동반한미완성치근첨의치아를치료하는술식으로서이의가없으나, 최근 ciprofloxacin; metronidazole; minocycline을 1:1:1의비율로혼합한 triple antibiotic mixture를이용한 regenerative endodontic procedures(reps) 가주목을받고있다. 이는기존치료에비해더바람직한장점을가지고있어향후임상적으로각광을받을것으로사료되며, 이를위해서그적용범위나방법을숙지하여야양호한결과를도출할수있을것이다. References 1. Banchs F, Trope M : Revascularization of immature permanent teeth with apical periodontitis: new treatment protocol? J Endod, 30:196-200, 2004. 200
2. Frank AL : Therapy for the divergent pulpless tooth by continued apical formation. JADA, 72:87-93, 1966. 3. Abbot PV : Apexification with calcium hydroxidewhen should the dressing be changed? The case for regular dressing changes. Aust Endod J, 24:27-32, 1998. 4. Andreasen JO, Farik B, Munksgaard EC : Longterm calcium hydroxide as a root canal dressing may increase risk of root fracture. Dent Traumatol, 18: 134-7, 2002. 5. Margelos J, Eliades G, Verdelis C, et al. : Interaction of calcium hydroxide with zinc oxide eugenol type sealers: a potential clinical problem. J Endod, 23:43-8, 1997. 6. Torabinejad M, Chivian N : Clinical applications of mineral trioxide aggregate. J Endod, 25:197-205, 1999. 7. Sarris S, Tahmessebi JF, Duggal MS, et al. : A clinical evaluation of mineral trioxide aggregate for rootend closure of non-vital immature permanent incisors in children - a pilot study. Dent Traumatol, 24:79-85, 2008. 8. Witherspoon DE, Small JC, Regan JD : Retrospective analysis of open apex teeth obturated with mineral trioxide aggregate. J Endod, 34:1171-1176, 2008. 9. American Association of Endodontics. Clinical considerations for a regenerative procedure. Available at: www.aae.org. 10. Iwaya SI, Ikawa M, Kubota M : Revascularization of an immature permanent tooth with apical periodontitis and sinus tract. Dent Traumatol, 17:185-187, 2001. 11. Murray PE, Garcia-Godoy F, Hargreaves KM : Regenerative endodontics: a review of current status and a call for action. J Endod, 33:377-390, 2007. 12. Shuping GB, Orstavik D, Sigurdsson A, et al. : Reduction of intracanal bacteria using nickel-titanium rotary instrumentation and various medications. J Endod, 26:751-755, 2000. 13. Sato T, Hoshino E, Uematsu H, et al. : In vitro antimicrobial susceptibility to combinations of drugs on bacteria from carious and endodontic lesions of human deciduous teeth. Oral Microbiol Immun, 8: 172-176, 1993. 14. Kim JH, Kim Y, Shin SJ, et al. : Tooth discoloration of immature permanent incisor associated with triple antibiotic therapy: a case report. J Endod, 36:1086-1091, 2010. 15. Chuensombat S, Khemaleelakul S, Chattipakorn S, et al. : Cytotoxic effects and antibacterial efficacy of a 3-antibiotic combination: an in vitro study. J Endod; 39:813-819, 2013. 16. Haapasolo M, Shen Y, Qian W, et al. : Irrigation in endodontics. Dent Clin North Am, 54:291-312, 2010. 17. Parirokh M, Torabinejad M : Mineral trioxide aggregate: a comprehensive literature review-part I: chemical, physical and antibacterial properties. J Endod, 36:16-27, 2010. 18. Petrino JA, Boda KK, Shambarger S, et al. : Challenges in regenerative endodontics: a case series. J Endod, 36:536-541, 2010. 19. Hoshino E, Kurihara-Ando N, Sato I, et al. : In-vitro antibacterial susceptibility of bacteria taken from infected root dentine to a mixture of ciprofloxacin, metronidazole and minocycline. Int Endod J, 29: 125-130, 1996. 201
국문초록 영구치의개방성치근첨에대한재생근관치료적의견 조용범 단국대학교치과대학치과보존학교실 치수괴사가있는미성숙치아를치료할때많은도전을받는데, 역사적으로수산화칼슘을장기간적용하여석회차단벽의형성을유도하는것이사용되어왔다. 2004년개방성근첨을치료할수있는 재혈관화 라는새로운방법이소개되어널리인정받게되었다. 기존의근첨형성술과이방법이다른점은근관을세항생제 (ciprofloxacin, metronidazole and minocycline) 로소독하고인위적으로근관내출혈을유도한다음, MTA로밀폐한다. 괴사된미성숙영구치를재생근관치료를성공적으로하였을경우, 지속적인치근의성장과상아질벽두께의증가, 및치근첨의폐쇄를얻을수있다. 이는치수- 상아질복합체의기능적회복과발달이궁극적으로자연치의유지에기여하는점이다. 주요어 : 근첨형성술, 미완성치아, 재생근관치료, 재혈관화, 수산화칼슘, MTA 202