대한치주과학회지 : Vol. 36, No. 4, 2006 덮개나사조기노출이임플란트의생존율에미치는영향 김용건, 이재관, 장범석, 엄흥식 * 강릉대학교치과대학치주과학교실 I. 서론 치아의결손부를수복하는방법중하나인임플란트치료법은오랜기간동안성공적인결과를보여왔다 1-4). 임플란트수술법은 1회법과 2회법으로나눌수있는데, 이중 2회법에의해식립된임플란트는점막에의해덮히게되며 5) 임플란트고정체를식립하는 1차수술과임시지대주를연결하는 2차수술사이의기간동안골유착이일어나게된다. 이시기에성공적인골유착을이루기위해서는임플란트에외상과감염이없어야하며점막은임플란트를완전히덮은상태로유지되어야하고, 임플란트주위골의높이는변하지않아야한다 6). 1) 임플란트덮개나사의조기노출은임플란트표면과구강과의직접적인통로를만들어주게되는데이때노출된임플란트표면의치태축적은연조직의염증을유발하고임플란트주위염이나임플란트주위골소실을야기할수있다 5). Adell 등 7) 은 15년간의관찰연구에서주의깊은수술계획과술후관리에도불구하고, 치료받은환자의 4.6% 에서점막 의조기천공이나타났다고보고하였으며, 덮개나사의조기노출은초기치조정골소실을초래하는유해한요인이될수있으므로임플란트와구강과의교통을막는것이성공적인골유착을이루는데있어중요하다고하였다. 이들은술후 6주동안의관찰을통하여구강과의직접적인통로가형성된경우에는천공된부위에절개를가하여판막의이동, 재봉합, 적절한의치수정을해주었다. Tal 등 8,9) 은 2회법으로식립된 372 개의임플란트중 51 개 (13.7%) 에서조기노출이나타남을보고하였고, Toljanic 등 10) 은 275 개의임플란트를대상으로한연구에서식립된임플란트의 5%, 환자의 14% 에서조기노출을보고하였다. 이들은임플란트덮개나사의노출이 1개또는그이상이있는경우가없는경우에비해 3.9 배의변연골소실을보인다고하였다. 또한 Block 과 Kent 등 11) 은덮개나사의조기노출이초기치조정골소실을야기한다고하였다. 이와달리덮개나사의조기노출이초기치유단계동안유해한효과를주지않는다는임상결과도보고되었다. Barzilay 등 12-14) 은동물실험에서덮개 * 교신저자 : 엄흥식, 강원도강릉시강릉대학로 120 강릉대학교치과대학치주과학교실, 210-702 ( 전자우편 : hsum@kangnung.ac.kr) 879
나사의조기노출이나임플란트주위에누공이 19% 정도나타났지만골유착을방해하지는않는다고하였고, Ericsson 등 15) 은덮개나사의조기노출이임플란트의골유착을이루는데큰부작용이없음을보고하였고식립시지대주의연결을동시에시행했을경우에성공적인골유착이가능함을보고하였다. 이러한논란속에서도덮개나사의조기노출이임플란트에있어어떠한영향을미치는지에대한연구는많이이루어지지않았다. 이연구의목적은 2회법으로식립된임플란트에서덮개나사의조기노출빈도를조사하고그것이임플란트에미치는영향에대해후향적으로분석하는데있었다. II. 연구재료및방법 1. 연구대상 2000년 1월부터 2002 년 12 월까지강릉대학교치과병원에내원하여 2회법으로식립한임플란트를대상으로하였다. 주기적인내원일에내원하지않은환자에식립된임플란트는연구대상에서제외하였다. 총 77 명의환자에서 219 개의임플란트를식립하였다. 남자는 49 명, 여자는 28 명이고연령은평균 46세였다 (Table 1,2). 다양한직경을갖는 219 개의임플란트를식립하였다 (Table 3). 이중상악에식립된것이 69 개 (31.6%), Table 1. Distribution of patient gender Male Female No. of patients 49(63.6) 28(36.4) 77(100) No. of implants 130(59.4) 89(40.6) 219(100) Table 2. Distribution of patient age Age(years) Patient(n=77) Implant(n=219) 10~19 1(1.3) 1(0.5) 20~29 4(5.2) 6(2.7) 30~39 11(14.3) 30(13.7) 40~49 31(40.3) 97(44.3) 50~59 24(31.2) 69(31.5) 60~69 6(7.8) 16(7.3) Table 3. Distribution of inserted fixtures according to position Position No. of implants % Upper anterior 19 8.7 Upper premolar 26 11.9 Upper molar 24 11.0 Lower anterior 23 10.4 Lower premolar 24 11.0 Lower molar 103 47.0 219 100 880
하악에식립된것이 150 개 (68.5%) 였다 (Table 3). 직경은 3.75 mm (61.6%) 가가장많았고, 4 mm (26.0%), 5.0 mm (9.6%), 그리고 3.3 mm (2.7%) 순이었다 (Table 4). 사용된임플란트시스템은 93 개 (42.5%) 의 3i 임플란트 (Implant Innovations, Palm Beach Gardens, FL, USA), 20 개 (9.1%) 의 Br nemark 임플란트 (Nobel Biocare, Göteborg, Sweden), 83 개 (37.9%) 의 Neoplant 임플란트 (Neobiotech, Korea), 23 개 (10.5%) 의 Avana 임플란트 (Osstem, Korea) 였다 (Table 5). 전체환자에서흡연자는 24 명 (31.2%), 비흡연자는 53명 (68.8%) 이었다 (Table 6). 2. 연구방법환자의의무기록지를이용하여임플란트덮개나사의조기노출여부, 노출부위및노출시기를확인하였으며, 조기노출의원인을알아보기위해성별, 나이, 수술부위, 임플란트고정체직경, 사용된 임플란트시스템, 흡연여부를조사하였다. 덮개나사의노출여부는의무기록지의기록과구내치근단방사선사진및파노라마방사선사진의연조직음영으로확인하였다. 임플란트의생존율을분석하기위해서 Albrektsson 과 Sennerby 16) 의실패기준을이용하였는데, 이는임플란트에동요가있는경우, 임플란트주위에방사선투과상이관찰되는경우, 매식후동통, 감염, 신경장애, 감각이상, 하악관의침범등의증상이존재하는경우이다. 이러한기준으로조사한임플란트를보철전실패 ( 식립및 2차수술 ) 와보철후실패로나누었고, 생명표분석을사용하여기능후 6 년까지의누적생존율을조사하였다. 2차수술시의변연골흡수량, 보철물장착후첫일년동안의변연골흡수량을조사하기위해평행촬영법으로촬영한구내치근단방사선사진을계측하여평가하였다. 구내치근단방사선사진촬영은임플란트식립직후, 임시지대주연결후및주기적인내원일에시행하였다. 주기적인내원일의간 Table 4. Distribution of inserted fixtures according to Implant diameter Diameter ( mm ) 3.3 3.75 4.0 5.0 6 (2.7) 135 (61.6) 57 (26.0) 21 (9.6) 219 (100) Table 5. Distribution of inserted fixtures according to implant system Implant System 3i Br nemark Neoplant Avana 93 (42.5) 20 (9.1) 83 (37.9) 23 (10.5) 219 (100) Table 6. Distribution of patients according to smoking Yes Smoking No 24 (31.2) 53 (68.8) 77 (100) 881
격은보철물장착후첫일년동안은 3개월, 6개월, 12 개월로하였고, 그이후에는 12 개월간격으로하였다. 변연골흡수량은구내치근단방사선사진에서측정하였으며, 임플란트의근심면과원심면의골흡수를측정하여더많은흡수를보이는면을기준으로하였다. 3. 통계분석 교하였다. 성별, 나이, 임플란트고정체직경, 시스템, 흡연여부가덮개나사의조기노출에미치는영향을평가하기위해서 Pearson's Chi-square test 와 Logistic regression test 를사용하였다. III. 결과 1. 임플란트의생존율 덮개나사의조기노출을보인임플란트와조기노출을보이지않은임플란트에서 2차수술과기능후첫일년동안의변연골흡수량은독립표본 T 검정으로비교하였다. 덮개나사의조기노출을보인임플란트와조기노출을보이지않은임플란트의생존율은 Pearson's Chi-square test 를사용하여비 219 개의임플란트중 9개가실패하였다. 덮개나사의조기노출을보인임플란트는 25 개 (11.4%) 였고이중 22개 (88.0%) 가생존하였고 3개 (12.0%) 가실패하였다. 덮개나사의조기노출을보이지않은임플란트는 194 개 (88.6%) 였고이중 188 개 (96.9%) 가생존하였고 6개 (3.1%) 가실패하였다 (Table 7,8, Figure 1). Survival Failure CSE Implants 22(88.0) 3(12.0) 25(11.4) NCSE Implants 188(96.9) 6(3.1) 194(88.6) 210(95.9) 9(4.1) 219(100) Table 7. Number of the survival implants Table 8. Life table analysis of total implant Time No. of implants CSE Implants NCSE Implants Failure CSR No. of implants Failure CSR CSR Place/Stage Ⅱ Sx 25 1 96.0 194 3 98.5 98.2 Stage Ⅱ Sx /load 24 0 96.0 191 0 98.5 98.2 Load / 1 yr 24 0 96.0 191 0 98.5 98.2 1 to 2 yr 24 2 88.0 179 2 97.4 96.3 2 to 3 yr 16 0 88.0 123 1 96.9 95.9 3 to 4 yr 10 0 88.0 57 0 96.9 95.9 4 to 5 yr 7 0 88.0 28 0 96.9 95.9 5 to 6 yr - - 88.0 1-96.9 95.9 CSR = cumulative survival rate Stage Ⅱ Sx / load = stage Ⅱ surgery to time of loading Place / Stage Ⅱ Sx = placement of implant to time of stage Ⅱ surgery load / 1 yr = time of loading to 1 yr 882
Figure 1. Cumulative survival rate according to the cover screw exposure. CSR = cumulative survival rate place / load = placement of implant to time of load load / 1 yr = time of loading to 1 yr 덮개나사의조기노출에따른임플란트의생존율의차이는통계적으로유의성이없었다 (p >0.05). 2. 변연골소실량 2차수술시덮개나사의노출을보인임플란트와덮개나사의노출을보이지않은임플란트의평균 변연골소실량은각각 0.48±0.60 mm, 0.095±0.27 mm로통계적으로유의한차이가있었다 (p <0.05) (Table 9). 첫일년동안기능후덮개나사의노출을보인임플란트와덮개나사의노출을보이지않은임플란트주위의변연골소실량은각각 1.00±0.59 mm, 0.50±0.65 mm로통계적으로유의한차이가있었다 (p <0.05)(Table 9). 3. 직경및시스템에따른덮개나사의노출빈도 덮개나사의노출을보인 25 개의임플란트중직경 3.75 mm가 135 개중 17개, 4.0 mm가 57 개중 3개, 5.0 mm가 21개중 5개, 그리고 3.3 mm는 6개중 0개가나타나직경에따른덮개나사의노출빈도는통계적으로유의한차이가없었다 (p >0.05)(Table 10). 시스템별로볼때 3i 가 93 개중 8개, Neoplant 가 83개중 9개, Avana 가 23개중 8개, Br nemark이 20 개중 0개가나타나시스템에따른덮개나사의 Table 9. Marginal Bone loss at stage II surgery and 1 year after loading Marginal Bone Loss ( mm ) Stage II surgery { { Load 1Y CSE implants * 0.48±0.60 * 1.00±0.59 NCSE implants 0.095±0.27 0.50±0.65 *: indicates significant difference between CSE implants and NCSE implants Table 10. Frequency of the early exposure according to implant diameter Implant Diameter ( mm ) 3.3 3.75 4.0 5.0 CSE implants 0 (0) 17 (12.6) 3 (5.3) 5 (23.8) 25 (11.4) NCSE implants 6 (100) 118 (87.4) 54 (94.7) 16 (76.2) 194 (88.6) 883
노출빈도가 Br nemark 임플란트에서통계적으로유의한차이가있었다 (p <0.05)(Table 11). 4. 성별및흡연에따른덮개나사의노출빈도덮개나사의노출을보인 25 개의임플란트중남자에서는 130 개중 16 개, 여자에서는 89 개중 9개가나타나성별에따른덮개나사의노출빈도는통계적으로유의한차이가없었다 (p >0.05)(Table 12). 흡연자에서는 58 개중 4개, 비흡연자는 161 개중 21 개로나타나흡연에따른덮개나사의노출빈도는통계적으로유의한차이가없었다 (p >0.05)(Table 13). IV. 고안 임플란트수술방법중 2회법은오랜기간동안성공적인결과를보여왔다 17-20). 2회법으로식립한임플란트에서덮개나사의조기노출은임플란트식립후골유착과치유에영향을미칠수있다. 이번연구에서는모두 external hex type 의임플란트를식립하여 11.4% 의점막천공을관찰하였다. 이러한결과는 Tal 등 8) 이보고한 13.7% 와비슷한수치이나, Adell 등 7) 이보고한 4.6% 와는차이를보인다. 이러한결과는외과적수술기법과임플란트시스템의차이에서비롯되는것으로보인다. Adell 등 7) 은임 Table 11. Frequency of the early exposure according to implant system Implant System 3i Br nemark Neoplant Avana CSE implants 8 (8.6) 0* (0) 9 (10.8) 8 (34.8) 25 (11.4) NCSE implants 85 (91.4) 20 (100) 74 (89.2) 15 (65.2) 194 (88.6) *: indicates significant difference between CSE implants and NCSE implants Table 12. Frequency of the early exposure according to patient gender Male Female CSE implants 16(12.3) 9(10.1) 25(11.4) NCSE implants 114(87.7) 80(89.9) 194(88.6) Table 13. Frequency of the early exposure according to smoking Yes Smoking No CSE implants 4 (12.5) 21 (15.1) 25 (11.4) NCSE implants 54 (87.5) 140 (84.9) 194 (88.6) 884
플란트의 external hex 부위를치조골정과같은위치에놓이게하여임플란트고정체를골정하방으로위치시켰다. 이러한방법은연조직의피개를용이하게하므로덮개나사의조기노출을줄일수가있다. Tal 등 8) 은임플란트의디자인에관한비교는없었지만 372 개의임플란트에서 192 개 (51.6%) 는 external hex type 의임플란트였고 180 개 (48.4%) 는 internal hex type 이었다. 이중덮개나사의조기노출의빈도는 external hex type이 16.1%(31/192), internal hex type이 11%(20/180) 였다. 이는 internal hex type 의경우덮개나사를임플란트에연결할때주위골과거의같은수준으로위치시키지만 external hex type 의경우는덮개나사가 1.0 mm의높이를가지기때문에임플란트에연결할때치조골정보다상방에위치하게된다. 즉임플란트플랫폼을동일한높이에위치시켰을경우 external hex type 의임플란트가 internal hex type 의임플란트보다상대적으로골정상방에위치함으로인해임플란트가점막에더큰장력을가하여덮개나사의조기노출이발생하였을것으로생각된다. 이번연구의실패기준에의하면 219 개의임플란트중 9개가실패하였다. 이중 4개는보철물장착전에골유착실패로발거하였고기능후 1 2년사이에 4개, 2 3년에 1개의임플란트가실패로간주되어발거하였다. 또한덮개나사의조기노출을보인임플란트는 25 개중 22 개 (88.0%) 가생존하였고 3 개 (12.0%) 가실패하였다. 덮개나사의조기노출을보이지않은임플란트는 194 개 (88.6%) 중 188 개 (96.9%) 가생존하였고 6개 (3.1%) 가실패하여, 생존율에있어각각 88.0% 와 96.9% 로차이가나지만, 조기노출을보인임플란트중실패한임플란트의개체수가부족하여통계적유의성을갖는결론을내릴수가없는한계가있었다. 이번연구에서는 219 개의임플란트중덮개나사의노출을보인임플란트와노출을보이지않은임플란트의 2차수술과기능후첫일년동안의변연골소실량에서통계적으로유의한차이가있었다 (p <0.05). 이는 Tal 등 5,8,21) 의연구결과와유사하다. Tal 등 5,8) 은술후 8~10 주에덮개나사의노출을임상적으로관찰하여, 임플란트를덮는점막이완전한형태를유지하는경우를 Class 0으로, 점막의터짐이관찰되는경우를 Class 1로, 점막이천공되어덮개나사가관찰되지만천공된점막의변연이덮개나사의변연에도달하지않은경우를 Class 2로, 천공된점막의변연의일부가덮개나사의변연까지도달한경우를 Class 3으로, 덮개나사가완전히노출된경우를 Class 4로분류하였다. 이들의연구에서 Class 0의경우에는평균 0.12 mm의변연골소실을보였으며, 이중 68.1% 에서골의변화를관찰할수없었고, 29.7% 에서 1 mm이내의변연골소실을보였으며, 단지 2.2% 에서 1~1.99 mm의변연골소실을보였다. Class 1의경우에는평균 0.4 mm의변연골소실을보였으며 Class 2의경우와 Class 3의경우에는각각 0.86 mm와 0.78 mm의변연골소실을보여 Class 0, 1, 2, 그리고 3사이에는통계적유의성이있다고보고하였다 21). 그러나이번연구에서사용한변연골소실계측은표준화되지않은선형측정법을사용하였으므로골과임플란트의최상방을인지하기가어려우며임플란트의연간골소실측정단위인 0.1 mm의측정이어렵고방사선의조사각에따라오차가나타날수있는점과인접면의평가만가능하다는것이한계점이라할수있다 22). 이러한점을보완하기위해서협, 설측골의평가및골의밀도까지평가가능한디지털영상분석방법이제안되고있으며 23) 재현오차를감소시키는기구를이용한표준화작업도제시되고있다 24). 덮개나사의조기노출원인은첫째, 판막에장력이과도하게작용할때일차유합이일어나지못하여절개연으로상피의이동이일어나창상의봉쇄가실패하게되고절개된조직에충분한정도의기질침착이일어나지않게되는경우, 둘째, 초기치유기간동안기계적인외상이나지속적인압력이절개연을분리시켜덮개나사주위의조직위축이나괴사를유발하는경우, 셋째, 덮개나사가풀려덮고있는점막을거상시키고이로인해과도한장력이발 885
생하는경우, 넷째, 골절제나임플란트식립과정에서골잔사들이남아서분리되고탈락하는과정에서점막을관통시키는경우, 다섯째, 임플란트가골정상방에위치하여덮힌점막에장력을가하고자극을주게되어노출되는경우이다섯가지로생각할수있다 7,25-28). 이번연구에서는덮개나사의조기노출은대부분이 8주내에일어났으며 2개의임플란트에서조직의괴사로인해덮개나사가노출되었다. 덮개나사의풀림이관찰되거나골잔사가점막을관통한경우는없었다. 직경에따른덮개나사의노출빈도는통계적으로유의한차이를보이진않았지만덮개나사가노출된임플란트중 3.75 mm직경의임플란트는 135 개를식립하였으며, 그중 12.6% 가노출되었고 5.0 mm의직경을갖는임플란트의경우는 21 개중 5개가노출되어 23.8% 를보였다. 이러한결과는 Wide 임플란트를약간골정상방으로위치시켰을때 Regular 임플란트나 Narrow 임플란트에비해 Wide 임플란트가점막에더큰장력을가하게되어노출된것으로생각된다. 시스템에따른덮개나사의노출빈도는 Br nemark 시스템에서통계적으로유의한차이를보였지만임플란트수가 9개로적어한계가있었으며, 성별및흡연여부도덮개나사의조기노출과연관성이없는것으로나타났지만흡연은치유과정을지연시킨다는보고 29-31) 가있으므로부가적인조사가필요하리라생각된다. 이번연구에서는덮개나사의조기노출의원인중연조직의두께및저작능력에따른고려가충분히이뤄지지않은면이있으며, 대상이된임플란트는노출에따른생존율을평가하기에는노출된임플란트의수가적어통계적유의성을도출하지못한한계가있다. 그러나전체생존율보다덮개나사가노출된임플란트에서누적생존율이낮음을확인하였고, 덮개나사가노출된임플란트에서변연골소실이더많음을확인하였다. 그러므로임플란트의골유착기간동안일어나는덮개나사의조기노출이임플란트의생존율과변연골소실에어떠한영향을미치는지를보다정확하게알기위해서는더많 은임플란트를대상으로하여좀더오랜기간동안지속적인관찰이이뤄져야할것이다. V. 결론및요약 이번연구에서는 77 명의환자에 2회법으로식립한 219 개의임플란트를대상으로임플란트덮개나사의조기노출원인과노출부위및노출시기를조사하고덮개나사가노출된경우와노출되지않은경우에있어서 2차수술시의변연골흡수정도, 보철물장착후첫일년동안의변연골소실및누적생존율을연구하여다음과같은결론을얻었다. 1. 덮개나사의조기노출은전체 219 개의임플란트중 25 개에서나타났으며 11.4% 의빈도를보였다. 2. 덮개나사가노출된임플란트와덮개나사가노출되지않은임플란트의누적생존율은각각 88.0% 와 96.9% 였다. 3. 변연골소실량을이차수술시와기능후 1년에측정하여비교했을때덮개나사가노출된임플란트가노출되지않은임플란트에비해더많은양의변연골소실을보였다 (p <0.05). 4. 임플란트직경, 성별, 흡연에따른덮개나사의노출빈도는통계적으로유의한차이가없었다 (p >0.05). VI. 참고문헌 1. Adell R, Lekholm U, Br nemark P-I surgical procedures in tissue-integrated prostheses. Oseointegration in clinical dentistry. Chicago, Quintessence Publishing Co. 1985; 211-232. 2. Jemt T, Lekholm U. Oral implant treatment in posterior partially edentulous jaws: a 5-year follow-up report. Int J Oral Maxillofac Implants 1993;8:635-640. 886
3. Lekholm U, Gunne J, Henry P, et al. Survival of the Br nemark implant in partially edentulous jaws: a 10-year prospective multicenter study. Int J oral Maxillofac Implants 1999;14:639-645. 4. Noack N, Willer J, Hoffmann J. Long-term results after placement of dental implants: longitudinal study of 1,964 implants over 16 years. Int J Oral Maxillofac Implants 1999;14:748-755. 5. Tal H, Dayan D. Spontaneous early exposure of submerged implants: III. Histopathology of perforated mucosa covering submerged implants. J Periodontol 2000;71:1231-1235. 6. Berglundh T, Lindhe J. Dimension of the peri-implant mucosa. Biologic with revisited. J Clin Periodontol 1996;23:971-973. 7. Adell R, Lekholm U, Rockler B, Br nemark PI. A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg 1981;10:387-416. 8. Tal H. Spontaneous early exposure of submerged implants: I. Classification and clinical observations. J Periodontol 1999;70:213-219. 9. Tal H, Dayan D. Spontaneous early exposure of submerged implants: II. Histopathology and histomorphometry of non-perforated mucosa covering submerged implants. J Periodontol 2000;71:1224-1230. 10. Toljanic JA, Banakis ML, Willes LA, Graham L. Soft tissue exposure of endosseous implants between stage I and stage II surgery as a potential indicator of early crestal bone loss. Int J Oral Maxillofac Implants 1999;14:436-441. 11. Block MS, Kent JN. Factors associated with soft- and hard-tissue compromise of endosseous implants. J Oral Maxillofac Surg 1990;48:1153-1160. 12. Barzilay I, Graser GN, Iranpour B, Natiella JR. Immediate implantation of a pure titanium implant into an extraction socket: report of a pilot procedure. Int J Oral Maxillofac Implants 1991;6:277-284. 13. Barzilay I, Graser GN, Iranpour B, Natiella JR, Proskin HM. Immediate implantation of pure titanium implants into extraction sockets of Macaca fascicularis. Part II: Histologic observations. Int J Oral Maxillofac Implants 1996;11:489-497. 14. Barzilay I, Graser GN, Iranpour B, Proskin HM. Immediate implantation of pure titanium implants into extraction sockets of Macaca fascicularis. Part I: Clinical and radiographic assessment. Int J Oral Maxillofac Implants 1996;11:299-310. 15. Ericsson I, Randow K, Glantz PO, Lindhe J, Nilner K. Clinical and radiographical features of submerged and nonsubmerged titanium implants. Clin Oral Implants Res 1994;5:185-189. 16. Albrektsson, T., Sennerby, L. "State of the art in oral implants", J Clin Periodontol 1991;18:471-481. 17. Buser D, Weber HP, Bragger U, Balsiger C. Tissue integration of one-stage ITI implants: 3-year results of a longitudinal study with Hollow-Cylinder and Hollow- Screw implants. Int J Oral Maxillofac Implants 1991;6:405-412. 18. Ericsson I, Nilner K, Klinge B, Glantz PO. Radiographical and histological characteristics of submerged and nonsubmerged titanium implants. An experimental study in the Labrador dog. Clin Oral Implants Res 1996;7:20-26. 19. Weber HP, Buser D, Donath K, et al. 887
Williams RC. Comparison of healed tissues adjacent to submerged and non-submerged unloaded titanium dental implants. A histometric study in beagle dogs. Clin Oral Implants Res 1996;7:11-19. 20. Clarizio LF. One-stage implants: An overview of their usefulness and techniques for placement. Postgrad Dent. 1996;3:3-12. 21. Tal H, Zvi Artzi. Spontaneous early exposure of submerged endosseous implants resulting in crestal bone loss: A clinical evaluation between stage I and Stage II surgery. Int J Oral Maxillofac Implants 2001;16:514-521. 22. Wennstrom, J.L, Palmer, R.M: "Consensus report of Session C. In Proceedings of the 3rd European Workshop on Periodontology", Berlin: Quintessence Publishing Co. 1999. 23. Fourmousis I, Br gger U. "Radiologic interpretation of peri-implant structures. In Proceeding of the 3rd European Workshop on Periodontology", Berlin: Quintessence Publishing Co. 1999. 24. Larheim TA, Eggen S. Measurements of alveolar bone height at tooth and implant abutments on intraoral radiographs. a comparison of reproducibility of Eggen technique utilized with and without bite imression. J Clin Peiodontol 1982;9:184-192. 25. Ordman LJ, Gillman T. Studies in the healing of cutaneous wounds. I. The healing of incisions through the skin of pigs. Arch Surg 1966;93:857-882. 26. Odland G, Ross R. Human wound repair. I. Epidermal regeneration. J Cell Biol 1968;39: 135-151. 27. Croft CB, Tarin D. Ultrastructural studies of wound healing in mouse skin. I. Epithelial behaviour. J Anat 1970 Jan;106: 63-77. 28. Gilio JA, Abubaker AO, Diegelmann RF. Physiology of wound healing of skin and mucosa. Oral Maxillofac Surg Clin North Am 1996;8:457-465. 29. Jones J, Triplett R. The relationship of cigarette smoking to impaired intraoral wound healing: A review of evidence and implications for patient care. J Oral Maxillofac Surg 1992;50:237-239. 30. Miller PD Jr. Root coverage with the free gingival graft. Factors associated with incomplete coverage. J Periodontol 1987;58: 674-681. 31. Preber H, Bergstrom J. Effect of cigarette smoking on periodontal healing following surgical therapy. J Clin Periodontol 1990;17 :324-328. 888
Effect of the early exposure of cover screws on the survival rate of implants Yong-Gun Kim, Jae-Kwan Lee, Beom-Seok Chang, Heung-Sik Um Department of Periodontology, College of Dentistry, Kangnung National University The early exposure of cover screws is a common complication of 2-stage implant technique. The exposure of cover screws between stage Ⅰ and Ⅱ surgery may cause inflammation in the soft tissues surrounding the implants, and lead to peri-implantitis or marginal bone loss. The purpose of this study was to evaluate the effect of the early exposure of cover screws on implants placed using 2-stage technique. Two hundred and nineteen implants in 77 patients were examined for cumulative survival rate, radiographic marginal bone level change, cause and frequency of the early exposure. The results were as follows: 1. Twenty-five implants showed early exposure of cover screws with a frequency of 11.4%. 2. Cumulative survival rate of the implants with early cover screw exposure was 88.0%, and that of the implants without cover screw exposure was 96.9%. 3. At the time of stage Ⅱ surgery and 1 year after loading, the marginal bone loss was greater around the implants with early exposure of cover screws than around the implants without cover screw exposure(p <0.05). 4. There was no statistically significant difference in the frequency of the early exposure according to the implant diameter, gender, and smoking(p >0.05). 2) Key words : 2-stage implant technique, cumulative survival rate, marginal bone loss, frequency of the early exposure. 889