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Vol. 31 No. 1, March 2012 치조골이심하게흡수된환자의수복 : Mini-implant 를이용한증례보고 이양진, 김영균 1 분당서울대학교병원치과보철과, 1 구강악안면외과 Rehabilitation of the severely atrophied edentulous patient: a case report using mini-implants Yang-Jin Yi, Young-Kyun Kim 1 Departments of Prosthodontics, 1 Oral and Maxillofacial Surgery, Section of Dentistry, Seoul National University Bundang Hospital, Seongnam, Korea An old patient wearing complete dentures during 35 years, with severe atrophied bone, suffered from poor retention, instability and insufficient chewing of dentures. At first, maxilla was restored with new complete denture for regain of vertical dimension and 4 years later, mandible was planned with mini-implant-retained overdenture. Mini-implants of mandible were early loaded and fabrication procedure was compressed simply with closed mouth impression technique. Without any inconvenience of patient, chief complaint such as numbness of mandible and insufficiency of mastication was disappeared. Although risk of mandible fracture should be considered during follow-up period, mini-implant on the atrophied mandible was considered simple modality for successful function. (JOURNAL OF DENTAL IMPLANT RESEARCH 2012;31(1):15-19) Key Words: Atrophy, Early loading, Mini-implant, Overdenture 서론 치조골이심하게퇴축된무치악환자의경우일반적인의치로는의치불안정으로저작에어려움을겪는일이빈번할분아니라사회적으로나심리적으로만족감이매우떨어진다고알려져있다 1). 또한하악골의경우협소한치조골폭경과높이에의해임플란트수복시에도골절이빈번하게일어남이보고되고있다. One-piece mini-implant는악골이심하게퇴축된곳, 인접치사이에제한된공간만을허용하는하악전치부같은해부학적한계를가진부위에 flap을열거나열지않고도 1회로시술이가능한최소침습적 (minimally invasive) 인장점을가지고있어술자와환자모두에게불편감이최소화될수있다 2,3). 보철적인측면에서는 abutment가일체화되어 (integrated) 있어 screw loosening이나 hollow type의 weak point를가지고있지않은구조적특징을가진다. 따라서 mini-implant로피개의치수복을할경우의치의단점은개선되면서해부학적으로위험을줄일수있어장기적으로안정적인결과를얻을수 있으리라생각된다. Mini-implant의생존률 4,5), 골흡수량 4,6), 저작력 6-9) 등에관한외국의다양한보고에비하여국내의관련연구들은매우드문실정이다. 본증례에서는국내에서개발된 mini-implant 중무치악환자에서골폭이좁거나일반적인 implant를적용하기어려운경우에사용되는의치형 (denture type) 을사용하여무치악환자를수복하였다. 이번증례를통해퇴축이심한하악골환자에서생길수있는위험사항을고려하여비침습적이면서환자가가장편한방법을택하여수복하는방법을제시하고자하였다. 증례보고 2007년 67세남자환자가상, 하악총의치불편감을주소로내원하였다. 젊은시절발치후 35년간상하완전틀니를장착하고있으며, 저작효율이너무낮아다시치료를원한다고하였다. 현재사용한의치는 25년간사용하였다고하였다. 안모는고경상실환자에서흔히볼수있는합 Received January 31, 2012. Revised February 10, 2012. Accepted February 15, 2012. cc This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creative commons.org/ licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 교신저자 : 김영균, 463-707, 성남시분당구구미로 173 번길 82, 분당서울대병원치과구강악안면외과 Correspondence to: Young-Kyun Kim, D.D.S., Ph.D., Department of Oral and Maxillofacial Surgery, Section of Dentistry, Seoul National University Bundang Hospital, 82, Gumi-ro 173beon-gil, Bundang-gu, Seongnam 463-707, Korea. Tel: +82-31-787-7541, Fax: +82-31-787-4068, E-mail: kyk0505@snubh.org JOURNAL OF DENTAL IMPLANT RESEARCH www.kaidimplant.or.kr

16 이양진ㆍ김영균 : 미니임플란트를이용한퇴축치조골의수복 Fig. 1. Patient showed decrease of vertical dimension. Frontal view. Profile. Fig. 3. High flange of maxillary complete denture from severe bone resorption. Esthetic profile from gain of vertical dimension. Fig. 2. Panoramic X-ray showing severe bone resorption of both arches. Maxilla with flabby tissues and flat vault. 죽한외모를가지고있었다.(Fig. 1) Panoramic x-ray 상에서아주얇은치조골상태를보였는데특히상악전치부와하악구치부의흡수가심했다. 구강검사결과 class V stage의무치악상태였으며상악은치조골흡수와함께전방부에 flabby tissue가있었으며입천장이평평한 flat vault type 등의유지력저하요인을가지고있었다.(Fig. 2) 환자는상악총의치와하악 implant 피개의치를권유받았으나상대적으로더불편한상악의치재제작만을원하였다. 통법에따라고경을회복하여총의치를제작하고진료를마쳤다. 유지력, 저작효율과함께심미적인만족감이회복되었다.(Fig. 3) 2011년 7월이번에는하악의불편감으로내원하였다. 2년여전부터틀니를빼고있어도욱신욱신거리며틀니를끼면조이고저작시멍멍한기분이든다고하였다. 하악골의퇴축 ( 잔존치조골의높이 ; 전치부 10 12 mm, 구치부 10 mm 미만 ) 이매우심한상태에서노출된이신경으로인한이공부위압박의결과로판단되었다. 그러나심한치조골퇴축으로인해 implant 식립시하악골골절의위험성이있고전신건강상태가불량하여골유도재생술이나일반직경의 implant 식립은적절하지않다고판단되었다. 합병증을최소화할목적으로 mini-implant 2개를식립한후피개의치를장착하기로계획하였다. 2011년 8월국소마취하에 #32, 42 부위에최소절개를가한후 flap 을제끼지않은상태에서직경 2.5 mm, 길이 8.5 mm의 MS port implant (Osstem Implant Co., Busan, Korea) 2개를식립하였

Yi YJ, Kim YK: Atrophied bone restored with mini-implant 17 다.(Fig. 4) 약 10일후기존의의치를조절하여연질이장재를이장하고조기기능하였다. 골유착이확인된 3개월후교합고경을재평가하고 base record와 rim을조정하여악간관계채득준비를마쳤다. 연질이장재를혼합하여적절한점도가될때까지기다렸다가 closed mouth impression tachnique으로기능인상을채득하였다. 환자에게약간의기능운동을지시한후경화가완료된순간악간관계를동시에채득하였다.(Fig. 5) 2011년 11월통법의과정을거쳐최종피개의치를장착하였다.(Fig. 6) 현재이공의통증은사라졌으며저작기능은성공적으로회복되었다.(Fig. 7) 현재약 6개월간합병증없이성공적으로사용하고있으나저작력증가가예상되므로 implant 주위염예방과함께하악골절방지에주안점을두고계속관찰중이다. Fig. 4. Two mini-implants were inserted to atrophied mandible. Superior wall of inferior alveolar canal was resorbed and mental foramen was not certain. Fig. 6. Conventional overdenture procedures. Fig. 5. Osseointegrated mini-implants. One step procedure of functional impression and jaw relation with closed mouth impression technique. Fig. 7. Esthetic profile after restoration of implant overdenture in mandible.

18 이양진ㆍ김영균 : 미니임플란트를이용한퇴축치조골의수복 고찰 본증례에서저자는상악은침습적이지않은 complete denture로수복하고, 매우심한치조골흡수를보이는하악에서는 flap을제끼지않고최소한의절개만을이용하여 mini-implant를식립하였다. 또한조기하중을통하여무치악기간을최소로줄였다. 골유착의성공이확인된 3개월후에는 closed mouth impression technique으로내원횟수와합병증을줄이는등환자의불편감을최소로하면서이공의통증없이성공적인결과를이끌어냈다. 상악에서는골지지가좋은환자에서새로만족스러운총의치를제작할경우와비교했을때 implant overdenture의저작기능과심리적인측면의향상은그리크지않았다. de Albuquerque Júnior 등 10) 은상악 overdenture의 palatal coverage가저작기능과만족도에미치는영향을조사한결과둘은차이가없었다고하면서이결과를골지지가좋은새로제작한상악총의치와비교했을때유의성있게높지않았다고하였다. 저자들의결론은상악 implant 수복은환자의골지지가좋을경우일반적인선택방법이아니라는것이었다. 물론총의치를 fixed implant supported complete denture (FICD) 로수복했을경우에는상, 하악모두저작기능이향상된다. 그러나하악을 FICD로수복하고상악이총의치일때와상악이 FICD일때를비교했을때기능차이가없었다는결과에서상악의저작기능회복은제한적이라는보고도있다 11). 본증례에서는상악전방부의가동연조직이있고심한골흡수로치조제가평편하며입천장도평평한형태를가진상태로유지력과저작측면에서굉장히불리한상태였으나새의치장착후환자의적응과만족도는매우커서굳이침습적인 implant overdenture를제작할필요성을느끼지못하였다. 총의치의경우저작력이떨어지므로자연히관련저작기능도자연치에비해떨어진다고볼수있다. 그러나하악의경우 implant overdenture로수복하면저작력은 2배정도 (60 200% 증가 ) 늘어나게되고저작효율도좋아진다 7). 한문헌에따르면총의치의평균최대저작력은 70 N ( 여성 ) 에서 140 N ( 남성 ) 인반면하악 implant overdenture는 140 N ( 여성 ) 과 230 N ( 남성 ) 정도였다 8). 다른조사에서는총의치가 170 220 N, 하악 implant overdenture가 310 340 N 정도였다. 저자들은하악 implant 지지 overdenture의저작력은자연치에비교해볼때 2/3선에그친다고하면서이것은상악대합치가총의치인상태에서측정한영향도있었을것이라고하였다 9). 2개의미니 implant를이용한피개의치의저작력은 ball attachment의경우 247.5 N, bar의경우 203.2 N을기록하였는데 6) 이것은평균직경의 implant 피개의치의저작력과비슷한범위에속한다. 그러나저작력의측정은실험의조건에따라크게달라지기때문에단순비교는어렵다. 본증례의결과저작력의증가와더불어이공에대한압박이없어진것은가장큰효과라고할수있다. 본증례에사용된 mini-implant는 abutment가일체화된 onepiece mini-implant이며피개의치에서높은생존률이보고되고있 다. Elsyad 등 4) 은 4개의 mini-implant를이용한피개의치의 3년누적생존률이 96.4%, 누적성공률이 92.9% 라하였다. Shatkin 등 5) 은지름 1.8 2.4 mm의 mini-implant 2,514개를 531명의환자에서 5 년 ( 평균 2.9년 ) 동안관찰한결과총생존률은 94.2% 였다고하였다. 저자들은피개의치와고정성보철에모두사용하여피개의치에서더큰성공률을보였다고하였다. One-piece mini-implant의높은생존률은 microgap이없는일체화구조의특징으로설명될수있다. Fixture와 abutment 사이에 microgap이있으면세균의누출로염증을유발하므로, microgap이치조골에서떨어져야변연골소실이작다고알려져있다 12,13). 이것은 two-piece implant와 one-piece implant의식립깊이에따라골흡수와연조직변화에큰차이를보였으며 one-piece implant의생물학적폭경이자연치와가장가깝고주변치조골소실이적었다는동물실험결과에서증명된다 13,14). 그러나임상에서피개의치에사용된 one-piece mini-implant 골흡수량에대한정보는드문편이다. Jofré 등 6) 은 one-piece mini-implant를이용한 overdenture에서 15개월후 ball group 1.40 mm, bar group 0.84 mm의골흡수량을보고하였다. 이결과는 1년후 1.2 mm의수직골소실, 0.62 mm의수평골소실을보였다는다른 overdenture 연구와매우유사하다 4). Microgap이없는 one-piece 임플란트라하더라도골흡수량은제품별 fixture 디자인이나직경, 표면처리형식, 초기식립깊이에따라영향을받을수밖에없다. 게다가 One-piece implant의특성상 flapless surgery로 1회수술이가능하지만환자의불편감이줄고 flap elevation에따른 bone loss가방지되는대신 blind technique이므로주변골상태에따라성적이차이날수있다 15). 심하게퇴축된하악골의경우 implant 식립에따른골절이자주보고된다 16-19). Oh 등 16) 은퇴축된하악골에서짧은 implant의 anchorage를얻기위해 wide diameter implant로 bicortical penetration을시행한증례에서골절이일어났다고하면서퇴축된치조골에서 implant의직경과치조골의보존이골절에영향을미침을보고하였다. 따라서 mini-implant의작은직경에서오는파절과, microstrain 집중으로인한치조골소실같은우려만해결된다면 mini-implant의사용은퇴축골에서매우유용한비침습적방법임에틀림없다. Implant overdenture 수복에서 2개에의해유지되는증례가 4개에비해성공률이떨어진다는증거는없다 20-22). 그러나 mini- implant 에서의결과도같은개념의적용이가능할지는밝혀진바없다. 하지만식립개수를최소로하는것은골절방지에도움이된다고볼수있다. 퇴축골에서골절이일어나는경우치료과정이매우어려워지므로계획단계에서특히주의해야한다 17). 한편 implant에의한골절뿐아니라 implant 주위염에따른골절도보고되고있다 18). 따라서철저한위생관리와함께정기적인방사선사진촬영으로치조골소실에대비해야한다. 저자등은심한하악골퇴축을보이는환자에서최소침습적인수술을통해 mini-implant 2개를식립하고피개의치로수복하여짧은관

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