대한치주과학회지 : Vol. 37, No. 4, 2007 방사선조사망상골이외방형골형성에미치는영향 정미현, 허익 *, 권영혁, 박준봉, 정종혁 경희대학교치의학전문대학원치주과학교실, 구강생물학연구소 I. 서론 임플란트를원활하게식립하고심미적인보철치료를하기위하여골이식재나차폐막을이용한치조제증대술이널리이용되어왔다. 1) Dahlin 등 1) 은차폐막하방에신생골이형성될수있는골증강술이라는용어를제안하였으며, Buser 등 2) 은차폐막을적용하여골의형성을유도하는골유도재생술이라는용어를제안하였다. 이들은외과적골결손부를형성한동물실험에서차폐막의사용여부에따라골결손부의치유양상이다른것을발견하였는데차폐막을사용하지않는골결손부는상부의결합조직에서유래하는세포의증식에의하여대부분결합조직으로채워졌고, 차폐막을사용한골결손부는결합조직세포의차단및선택적골세포의증식으로골조직으로치유된결과를얻을수있었다. 골유도재생술에사용되는차폐막은여러가지재료로만들어지며, 주로많이사용되는비흡수성차폐막인 e-ptfe(expanded-polytetrafluoroethylene) 나흡수성재료인교원질차폐막은견고성 이부족하여골결손부내로막의붕괴를일으켜서골재생을위한공간의부족을초래할수있다. 이를보완하기위하여티타늄강화 e-ptfe(titanium-reinforced expanded-polytetrafluoroethylene) 막 3) 을사용하거나, 작은스크류나핀을이용하여막을고정할수있고, 막하방에여러가지골이식재를충전하여공간을유지시킬수도있다. Jovanovic 등 4) 은 5마리성견을이용한연구에서티타늄강화 e-ptfe 막을사용시 6개월의치유기간후 4mm정도의외방형골재생을보고하였고, 티타늄강화 e-ptfe 막이부가적인골이식재의충전없이도공간을유지할수있으며이전의 e-ptfe 막과비교시더많은양의골을형성할수있다고제안하였다. 차폐막에의하여형성된하방의재생공간을보다견고하게유지하고골재생효과를증가시키기위하여여러가지골이식재를충전하기도한다 5). 골유도재생술에사용되는골이식재의역할은막의붕괴를방지하여골형성세포의성장을위한공간을유지하며, 다공성의구조를형성하여골전도성을 * 교신저자 : 허익, 서울시동대문구회기동 1번지경희대학교치과대학치주과학교실, 130-702 ( 전자우편 : yherr@khu.ac.kr) * 본연구는보건복지부보건의료기술진흥사업 (03-PJI-PG1-CH08-0001) 의지원에의하여이루어진것임. 791
증가시키고, 혈병을고정하여치유조직이수축되는것을방지한다고하였다 6). 이러한골이식재가차폐막하방에서골형성을촉진시킨다고보고한연구들 7-10) 이있는반면골이식재를사용하지않아도차폐막만견고하게유지된다면골형성이가능하다는보고도있다 10-15). 자가골은생체적합성이가장우수하며, 막하방의재생공간을충분한기간동안유지할수있고, 신생골로대체될수있고 2,16) 주변의골형성세포를자극하여골형성을촉진하고유도할수있어서 17,18) 가장좋은골이식재료이나구강내에서자가골을충분히채득하기어렵고타부위의수술이필요하다는단점이있다. 따라서이를대체할골이식재에대한연구가계속이루어지고있다 19,20). 탈회동결건조골은이러한자가골의한계를극복할수있다고하였으며 7,14), 골유도성을가지고있으나 21-23), 흡수가너무빨라서장기간차폐막의공간을유지하는효과는감소하였다 11). 반면동결건조골은흡수속도가느려서장기간동안공간을유지할수있는장점이있다 7,10,11,24). 동종골의소독은크게동결건조와방사선조사로분류할수있다. Grieb 등 25) 은방사선조사망상골이골이식재로서안전하고충분한물리적강도를가지고있다고보고하였다 26,27). Lundgren 등 28) 은티타늄막을이용한수직골증대술을시행한연구에서골재생효과를극대화시키기위해서는충분한변연부폐쇄를통한결합조직의침투를막아야한다고주장하였으며, Schmid 29) 와 Linde 30) 의차폐막을이용한골증대술연구에서도완전한골재생을얻지못했던이유가변연부를통한연조직의침투에의한것이라고결론지었다. 그이후핀이나스크류등을이용하여차폐막을골표면에밀착시키며, 차폐막의고정을강조한연구들이발표되었다 31,32). 김등 33) 은토끼두개관실험모델에서차폐막만을사용한실험군에서보다차폐막과골이식재를동시에사용한실험군에서보다많은외방형골형성 (Exophytic bone formation) 이일어났다고보고하였다. 이번연구에서는구강외모델에서 이루어진외방형골형성의성공적인결과가구강내모델에서적용가능한지를평가하고, 티타늄강화 e-ptfe 막을이용하여단독으로사용할경우의골재생효과와임상에서널리이용되는방사선조사망상골을같이사용할경우골재생이증가하는지에관하여조직학적및조직계측학적으로비교분석하기위하여실험적으로형성한수평골결손부에실험이이루어졌다. 또한주변이골로둘러싸인인레이형태의골결손부는주위골로부터활발한골재생이일어나골이식재자체의골형성능력을구별하기어렵기때문에이번실험에서는기존골의외부로외방형골형성을유도하는실험디자인을하여골재생에관여하는인접골의영향을배재한상태에서골이식재가골재생에미치는효과를살펴보고자하였다. II. 연구재료및방법 1. 연구재료차폐막으로는티타늄강화 e-ptfe 막 (TR9W, W. L. Gore & Associates INC., U.S.A) 을길이 10 mm, 폭 5mm, 높이 4mm되는직육면체의형태로만들어서 ethylene oxide로소독하여사용하였고, 골이식재로는방사선조사망상골 (Irradiated cancellous human bone(icb), Rocky Mountain Tissue Bank, U.S.A) 을사용하였다. 2. 실험동물생후 1.5 년, 평균체중 12Kg 인웅성비글견 12 마리를사용하였으며, 전실험기간동안창상을보호하기위하여유동식을공급하였으며, 치태조절을위하여클로르헥시딘을사용하였다. 3. 연구방법 1) 대조군과실험군설정 792
실험동물중티타늄강화 e-ptfe 막만을사용한비글견을대조군으로, 티타늄강화 e-ptfe 막과방사선조사망상골을함께사용한비글견을실험군으로설정하였으며, 12 마리의비글견중전실험기간동안차폐막이구강내노출되지않은 4마리씩을대조군과실험군의결과로분석하였다. 2) 수술과정케타민 ( 유한양행, 한국 ) 과럼푼 ( 바리엘코리아, 한국 ) 을 1:1 로섞은후 5ml를근육주사하여전신마취를시행하고, 수술부위는 2% 염산리도카인 (1:100,000 epinephrine 함유, 광명, 한국 ) 으로국소마취를한다음전층판막을거상하고모든소구치치근을절제하여각각의치근을발거하였다. 이후기저골까지수평골결손부를높이가 5mm가될때까지치조골을삭제한후 (Figure 1) 판막을제위치시켜봉합하였다. 발치및수평골결손부형성 8주후하악소구치부위에서치조정절개후전층판막을거상하였다. 주수하에 round carbide bur(hp Long #6) 를이용하여피질골을제거하였다. 골내출혈을확인한후길이 10 mm, 폭 5mm, 높이 4mm의형태로미리제작된티타늄강화 e-ptfe 막내부에생리식염수에 30 분간침적한방사선조사망상골을채우고핀으로고정하였다 (Figure 2). 이를실험군으로하였고, 대조군의경우방사선조사망상골의사용없이티타늄강화 e-ptfe 막만을사용하였다. 비흡수성봉합사 (e-ptfe suture material, TR9W, W.L. Gore & Associate Inc., U.S.A) 로전층판막을봉합하고술후 3일까지겐타마이신 ( 동화약품, 한국 ) 2ml와케토프로펜 ( 유니바이오테크, 한국 ) 를근육주사하였고, 전실험기간동안클로르헥시딘으로치태조절을하였다. 3) 조직준비및분석재생수술 8, 16 주후에두군의실험동물 4마리씩을각각과량의졸레틸 (Virbac, France) 을근육주사하고경동맥을통한 4% 파라포름알데하이드고정액으로관류고정하여희생시켰다. 차폐막을포함하여치조골일부를절제하여조직절편을채득하였다. 4% 파라포름알데하이드로한달이상고정한후통법에따라비탈회조직표본을제작하였다. 비탈회조직표본은시편을흐르는물에세척한후 70% 에탄올에 1일간담가둔후, Villanueva bone stain 용액에 3일간담궈염색시킨다음 4, 70%, 90%, 95%, 100% 에탄올에각각 1일씩담구어탈수시키고 methyl methacrylate monomer, MMA polymer(wako, Japan) 와 benzoyl peroxide 를섞어만든레진으로포매하였다. 시편은경조직절단기 (Maruto Co., Japan) 률이용하여 500 μm두께로절단한후경조직연마기 (Maruto Co., Japan) 로 80 μm의절편을얻었다. 조직슬라이드를 BX51 Olympus 현미경으로조직관찰후에 DP71 현미경용카메라로 40 배에서디지털사진촬영후 Tomoro Scope Eye(Techsan, Korea) 프로그램을이용하여조직계 Figure 1. Buccal clinical view to show the horizontal defect after tooth extraction and ostectomy Figure 2. Buccal clinical view to show the barrier membrane on the residual ridge 793
측학적분석을시행하였다. 4. 신생골형성의조직학적계측 1. 조직학적소견 III. 연구성적 차폐막의내면과골면으로이루어지는면적과막하방에새로형성된골조직의면적을계산한후 (Figure 3) 아래의공식에대입하여신생골형성의백분율계산하고표시하였다. 1) 대조군 8주티타늄강화 e-ptfe 막은실험기간동안변형없이공간을잘유지하고있으나막내부에빈공간이존재하며, 기존골표면으로부터약간의소주골형성을관찰할수있고, 형성된소주골상방으로결합조직층이보이며막변연부위의연조직침투는관찰되지않았다 (Figure 4). 2) 대조군 16 주 8주소견에비해서소주골의형성이증가되었고, 재생공간내부에빈공간이감소하였다. 기존골표면에흡수가관찰되고, 형성된소주골상방으로결합조직층이관찰되나그양이 8주군에비하여감소되었다 (Figure 5). Figure 3. schematic diagram used in histomorphologic analysis 신생골형성의백분율 Sum of areas of newly formed bone( mm2 ) Area of space created by the TR e-ptfe membrane( mm2 ) 100 3) 실험군 8주방사선조사망상골입자가연조직에둘러싸여있으며일부에서는기존골표면으로부터많은양의소주골이형성되어골이식재와연결되어있었다 (Figure 6A). 100 배로검경시, 형성된일차골원이관찰되었다 (Figure 6B). Figure 4. Control site 8weeks. Newly formed bone, connective tissue and empty space were shown. (Villanueva bone stain, Original magnification 20) Figure 5. Control site 16weeks. Newly formed bone and empty cavity were shown. (Villanueva bone stain, Original magnification 20) 794
Figure 6A. Test site 8weeks. Tissues filled in the space. (Villanueva bone stain, Original magnification 20) Figure 6B. Inset of Fig. 6. Primary osteon was shown. (Villanueva bone stain, Original magnification 100) Figure 7A. Test site 16weeks. Newly formed bone almost filled in the space. (Villanueva bone stain, Original magnification 20) Figure 7B. Inset of Figure 7. Haversian canals and osteocytes were shown. (Villanueva bone stain, Original magnification 100) Figure 7C. Inset of Figure 7. Lamellar bone were shown. (Villanueva bone stain, Original magnification 100) 4) 실험군 16 주이식재입자는소량만이관찰되었고, 재생공간의대부분이새로형성된소주골로채워져있었다. 이식재와소주골의경계가불명확하였다. 막변연부위로부터연조직유입은관찰되지않았다 (Figure 7A). 고배율로확대하여관찰시, 신생골과기저골사이의 Figure 7D. Inset of Figure 7. Remaining graft particle was shown. (Villanueva bone stain, Original magnification 100) 경계부위에서다수의골세포 (Figure 7B) 가보였으며, 기저골상방부에서도성숙된신생골이관찰되었다 (Figure 7C). 하지만차폐막의직하방부위에는연조직으로채우져있으며골이식재의입자가관찰되었다 (Figure 7D). 795
2. 조직계측학적분석 1) 실험기간에따른골형성변화 차폐막에의하여형성된공간내에형성된신생 골조직의평균면적비율의경우대조군 8주, 대조군 16 주, 실험군 8주, 실험군 16 주에서각각 23.40%, 46.26%, 40.23%, 47.11% 이었다. 실험기간에따른신생골의형성양은 8주에비하여 16 주에서 Table 1. Newly-formed bone in the space created by the TR-ePTFE membrane at 8weeks after surgery Table 2. Newly-formed bone in the space created by the TR-ePTFE membrane at 16weeks after surgery Dog New bone(%) Dog New bone(%) 1 (Rt) 23.37 3 (Rt) 47.59 1 (Lt) 24.34 3 (Lt) 46.99 2 (Rt) 23.59 4 (Rt) 45.01 2 (Lt) 22.31 4 (Lt) 45.44 Mean 23.40 Mean 46.26 Standard Deviation 0.84 Standard Deviation 1.23 Table 3. Newly-formed bone in the space created by the TR-ePTFE membane and filled with ICB at 8weeks after surgery Table 4. Newly-formed bone in the space created by the TR-ePTFE membane and filled with ICB at 16weeks after surgery. Dog New bone(%) Dog New bone(%) 5 (Rt) 40.85 7 (Rt) 48.19 5 (Lt) 38.73 7 (Lt) 47.30 6 (Rt) 41.73 8 (Rt) 47.03 6 (Lt) 39.59 8 (Lt) 45.92 Mean 40.23 Mean 47.11 Standard Deviation 1.33 Standard Deviation 0.93 ICB : Irradiated Cancellous Bone ICB : Irradiated Cancellous Bone Table 5. Histomorphometric analysis Group Period Newly-formed bone(%) (mean ± S.D.) 8 weeks (n=4) 16 weeks(n=4) Control 23.40±0.84 46.26±1.23* Test 40.23±1.33 47.11±0.93* * statistically significant difference between two experimental time periods (p<0.05) statistically significant difference between two experimental groups (p<0.05) The statistical significance was analyzed by Mann Whitney U test. 대조군및실험군공히통계학적으로유의하게증가하였다 (p<0.05)(table 1~5). 2) 두군간의골형성변화재생수술 8주후에실험군에선 40.23%, 대조군에선 23.40% 로실험군이대조군에비하여통계학적으로유의하게골형성이많았고 (p<0.05), 16 주후에실험군에서 47.11%, 대조군에서 46.26% 로대조군에비하여실험군에서많은골형성이있었으나통계학적유의성은없었다. 796
IV. 총괄및고찰 비글견에서외과적으로형성한구내위축치조제에서외방형골재생을유도하고자티타늄강화 e-ptfe 막과방사선조사망상골을함께사용하여골유도재생술을시행하였을때, 골이식재의사용이외방형골재생에부가적효과가있는지여부를알아보고자하였다. 티타늄강화 e-ptfe 막은티타늄으로차폐막을강화하였기때문에다른차폐막에비하여견고한기계적성질을가지며원하는형태로쉽게구부릴수있어서재생공간의붕괴없이골재생을얻을수있고, 광범위하게치주및임플란트영역에서사용되고있어서이번실험에사용하였다. 또한막을치조제에고정하기위하여핀을사용함으로써막의변연부로부터연조직의침투를방지하려하였다. 주변의잔존골조직으로부터골형성세포의이주에의한골재생을배제하고자인레이형태의골내결손부가아닌외방형골증식모델을사용함으로써티타늄강화 e-ptfe 막과방사선조사망상골의재생공간확보및유지능력및수직골재생에미치는효과를알아보고자하였다. 외방형골재생능력을알아보고자비글견의구강내잔존치조제를이용한실험모델이라고할수있다. 이번연구에서는총 12 마리의비글견을사용하여구강내잔존치조제에 4mm높이의차폐막을사용하였으나이들중 4마리의비글견에서차폐막이노출되어차폐막이노출되지않은 8마리에서만얻어진결과를분석하였다. 차폐막의조기노출을방지하기위하여장력없는봉합을하고, 1주에 5일간클로르헥시딘을사용하여치태조절을하였지만, 습관성이갈이와개장을씹어차폐막이조기에노출되는경우가있었다. 또한외방형실험모델자체도차폐막의조기노출을일으킬수있는소인이라고사료된다. 임상에서도수직치조제증대술후치유과정중에연조직의창상열개에의한차폐막의조기노출이가장큰문제이며, 그원인으로는판막봉합시지나친장력을가하여혈액공급이감소되는것과특히너무많은양의수직골증대를시도하는경우라고할수있다. 다행히차폐막이노출되지않은 8마리의개중 4마리에서대조군을나머지 4마리에서실험군의결과를얻을수있었다. 골유도재생술을시행하는경우재생공간내로골아세포의분화및이주를돕고, 혈액공급을증가시키기위하여치조제표면의피질골을천공하거나제거한다. 피질골천공이골형성을촉진한다는보고가있는반면 34-37), Lundgren 등 28) 은피질골을천공하거나제거하지않아도신생골형성이가능하다고보고하였다. 이번연구에서는골아세포의이주및혈액공급목적으로피질골을제거하였으나그효과에대한검증은판단하기어려웠다. Simion 등 38) 은 4mm높이이상의수직치조제증대술시완전하게골로채워지지않는이유를다음과같이제안하였다. 첫째, 차폐막을입체적인해부학적구조에적용할때막의변연부를밀착시킬수없기때문에연조직이이곳을통하여침투하여골의재생을방해한다. 이번연구에서는차폐막변연부하방으로침투되는결합조직은관찰되지않았다. 이는고정핀으로차폐막을고정하여움직이지않게하였고, 외부의압력에저항할수있게하였으며, 차폐막의변연부를치조제표면과밀착시킴으로써효과적으로결합조직의침투를차단할수있었기때문이었다. 둘째, 차폐막하방에혈병이가득채워져도초기치유단계에서수축이일어나골의형성양을감소시킬수있다. 이를최소화하기위하여골이식재의사용을추천하였다. 이번연구에서도방사선조사망상골을차폐막내부에충전한실험군에서대조군에비하여실험 8주에각각 23.40%, 40.23% 로약 2배정도의신생골형성증가를보였다. 세번째, 차폐막에의하여형성된공간상층부는혈액공급이부족하여골형성이감소한다. 네번째, 완전한골재생을얻기위해서는보다오랜치유기간이필요하다. 즉골재생을얻기위하여 9개월정도의치유기간이필요하다고하였다. 이번연구에서도 8주에비하여 16 주에대조군에서는신생골의형성이 23.40% 에서 46.26% 로증가하였으며, 실험군에서도 40.23% 에서 47.11% 로증가하였다. 16 주에대조군과실험군의신 797
생골형성은 46.26% 와 47.11% 로대조군보다많았으나통계학적유의성도없었다. 그이유는대조군에서시간경과에따라골광화가증가하였기때문인것같다. 이번연구에서는전실험기간동안티타늄강화 e-ptfe 막에서함몰이나변형이없는것으로관찰되어재생공간의유지에충분한강도를가지고있었으며염증반응이없었던것으로보아조직친화성이우수하였다. Piattelli 등 6) 은사람을이용한조직학적검사에서동결건조골의경우기저골에서멀리떨어져있어도골아세포가활발하게신생골을형성하며이식편들이신생골에의하여둘러싸여있는소견을관찰하여, 골전도성은있으나골유도성은없다고결론지었다. Shanman 39) 은이식재를사용하지않는것이좋으나공간유지를위하여사용해야한다면흡수속도가느린동결건조골이유리하다고하였다. Tatum 등 40) 은상악동내에골이식재를사용한후장기간에걸쳐관찰한실험에서가장효과적인골이식재는자가골이나채취량에한계가있어서대체이식재로서방사선조사망상골이가장우수하였다고보고하였다. 이번연구는티타늄강화 e-ptfe 막이충분한강도를가지고있어재생공간을유지할수있음을보여주었고방사선조사망상골을함께사용할경우차폐막에의하여형성된공간내에채워지는혈병을안정화시키고, 혈병의수축을감소시켜신생골형성을증가시켰으며, 고정핀에의한차폐막의변연부봉쇄가잘이루어져서비교적많은양의신생골형성을관찰할수있었다. 앞으로는수직골재생을검증하기위한구강내실험모델에서창상치유에미치는여러가지요소및골이식재를대체할수있는약제에대한연구가이루어져야하며, 수직골재생의한계를알아보는연구가이루어져야할것으로사료된다. V. 결론 이번연구의목적은실험적으로형성한구강내 위축치조제에서외방형골재생을유도하고자티타늄강화 e-ptfe 차폐막에부가적으로방사선조사망상골을사용하여골유도재생술을시행하였을때신생골형성에효과가있는지를알아보고자하였다. 생후 1.5 년, 평균체중 12kg 인웅성비글견 12 마리를사용하였고, 하악의모든소구치를발치하고기저골까지외과적으로수평골결손부를형성한후전층판막을봉합하였다. 8주후전층판막을거상하고하악소구치부위치조제의피질골을제거한후그상방에길이 10 mm, 폭 5mm, 높이 4mm의직육면체형태로만든티타늄강화 e-ptfe 막을핀으로고정하여수직치조제증대술을시행하였다. 대조군은티타늄강화 e-ptfe 막만을사용하였고, 실험군은티타늄강화 e-ptfe 막과방사선조사망상골을함께사용하였다. 재생수술 8, 16 주후에구강내차폐막이노출되지않은대조군 4마리, 실험군 4마리씩을각각희생시켜, 차폐막을포함한일부의조직절편을채취하여통법에따라비탈회조직절편을제작하여조직학적및조직계측학적으로분석하여다음과같은결론을얻었다. 1. 재생수술후 8주에비하여 16 주에대조군은 23.40% 에서 46.26% 로, 실험군은 40.23% 에서 47.11% 로각각외방형신생골의형성이증가하였다 (p<0.05). 2. 재생수술 8주후에실험군에선 40.23%, 대조군에선 23.40% 로실험군이대조군에비하여통계학적으로유의하게외방형신생골이많이형성되었고 (p<0.05), 16 주후에실험군에서 47.11%, 대조군에서 46.26% 로대조군에비하여실험군에서많은골형성이있었으나통계학적유의성은없었다. 3. 고정핀은차폐막을치조제와밀착시켜서막의이동을방지함과동시에결합조직의내부유입을차단하였다. 이상의결과를미루어보면, 골이식재의효과를검증하기위한외방형골형성구강내모델은효과적 798
이었으며, 차폐막을단독으로사용하는것보다, 방사선조사망상골을함께사용하는것이외방형골형성에도움을줄수있다는것을제시하고있다. VI. 참고문헌 1. Dahlin C, Sennerby L, Lekholm U. Generation of new bone around titanium implants using a membrane technique: An experimental study in rabbits. Int J Oral Maxillofac Implants 1989;4:19-25. 2. Buser D, Dula K, Belser U, Hirt HP, Berthold H. Localized ridge augmentation using guided bone regeneration. I. Surgical procedure in the maxilla. Int J Perio Rest Dent 1993;13:29-45. 3. Jovanovic SA, Nevins M. Bone formation utilizing titanium-reinforced barrier membranes. Int J Perio Rest Dent 1995;15: 57-69. 4. Jovanovic SA, Schenk RK, Orsini M, Kenney Eb. Supracrestal bone formation around dental implants: An experimental dog study. Int. J Oral Maxillofac Implants 1995;10:23-31. 5. von Arx T, Cochran DL, Hermann JS, Schenk RK, Buser D. Lateral ridge augmentation using different bone fillers and barrier membrane application. A histologic and histomorphometric pilot study in the mandible. Clin Oral Impl Res 2001;12:260-269. 6. Slott C, Lundgren D. Augmentation of calvarial tissue using nonpermeable silicone domes and bovine bone mineral. An experimental study in the rat. Clin Oral Impl Res 1999;10:468-476. 7. Piattelli A, Scarano M, Piattelli M. Comparison of bone regeneration with the use of mineralized and demineralized freeze-dried bone allografts: A histologic and histochemical study in man. Biomaterials 1996;17:1127-1131. 8. Nevins M, Mellonig JT. Enhancement of the damaged edentulous ridge to receive dental implants: A combination of allograft and the GORE-TEX membrane. Int J Perio Rest Dent 1992;12:97-111. 9. Nevins M, Mellonig JT, Clem DSC III, Reiser GM, Buser DA. Implants in regenerated bone: Long term survival. Int J Perio Rest Dent 1998;18:35-45. 10. Feuille F, Knapp CI, Brunsuold MA, Mellonig JT. Clinical and histologic evaluation of bone replacement grafts in the treatment of localized alveolar ridge defects. Int J Perio Rest Dent 2003;23: 29-35. 11. von Steenberghe D, Johansson C, Quirynen M et al. Bone augmentation by means of a stiff occlusive titanium barrier. A study in rabbits and humans. Clin Oral Impl Res 2003;14:63-71. 12. Schenk RK, Hardwick WR, Dahlin C. Healing pattern of bone regeneration in membrane protected defects. A histologic study in the canine mandible. Int J Oral Maxillofac Impl 1994;9:13-29. 13. Becker W, Dahlin C, Lekholm U. The use of e-ptfe barrier membranes for bone promotion around titanium implants placed into extraction socker: A prospective multicenter study. Int J Oral Maxillofac Implants 1995;9:31-40. 14. Cortellini P. Localized ridge augmentation using guided tissue regeneration in humans. Clin Oral Impl Res 1993;4:203-209. 15. Scantlebury TV. A decade of technology 799
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The effect of irradiated cancellous human bone on exophytic bone formation in residual ridge of the beagle dog Mi-Hyun Chung, Yeek Herr *, Young-Hyuk Kwon, Joon-Bong Park, Jong-Hyuk Chung Deparment of Periodontology and Institute of Oral Biology, School of Dentistry, Kyung Hee University The purpose of this study was to evaluate exophytically vertical bone formation in residual ridge of the beagle dog by the concept of guided bone regeneration with a titanium reinforced e-ptfe membrane combined with irradiated cancellous human bone. Twelve male beagle dogs(mean age 1.5 years and mean weight 12kg) were used for this study. The alveolar ridges after extraction of all mandibular premolars were surgically and horizontally removed. At 8 weeks after extractions, full-thickness flap was reflected and cortical bone was removed with round bur and copious irrigation. Rectangular parallelepiped(10 mm in length, 5mm in width, and 4mm in height) bended with titanium-reinforced e-ptfe(tr e-ptfe) membrane was placed on the decorticated alveolar ridge, fixed with metal pins and covered with full-thickness flap and assigned as a control group. Test groups were treated with TR e-ptfe membrane filled with irradiated cancellous human bone. Of twelve beagle dogs, four control dogs and four test dogs without membrane exposure to oral cavity were sacrificed at 8 and 16 weeks respectively. The surgical sites were dissected out, fixed in 4% buffered formaldehyde, dyed using a Villanueva staining technique, and processed for embedding in plastic resin. The cutting and grinding methods were routinely processed for histologic and histomophometric analyis of exophytic bone formation as well as statistical analysis. The results of this study were as follows: 1. Exophytic bone formation in the both of experimental groups was increased respectively after surgery from 23.40% at 8 weeks to 46.26% at 16 weeks in the control groups, from 40.23% at 8 weeks to 47.11% at 16 weeks in the test groups(p<0.05). 2. At 8 weeks after surgery, exophytic bone formation was made 40.23% in the test groups and 33.40% in the control groups. Exophytic bone formation was significantly made in the test group more than in the control group. At 16 weeks after surgery, exophytic bone formation was made 44.11% in the test groups and 46.26% in the control groups. Exophytic bone formation was made in the test groups more than in the control groups, but there was no statistically significant differences. 802
3. The membrane was fixed with metal pins to closely contact it to the bone surface. So, collapse and deviation of the membrane could be prevented and in growth of connective tissue also could be blocked from the periphery of the membrane. On the basis of these findings, we suggest that intraoral experimental model for exophytic bone formation may be effective to evaluate the effect of bone graft material. And it indicates that combined use of membrane and ICB graft material is more effective than use of membrane only for exophytic bone formation. 2) Key words : irradiated cancellous bone, exophytic bone formation 803
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