Journal of Korean Academy of Oral Health 2014 March 38(1): Original Article QLF-D 와 OCT 를이용한초기인공우식병

Journal of Korean Academy of Oral Health 2014 March 38(1):10-16 http://dx.doi.org/10.11149/jkaoh.2014.38.1.10 Original Article QLF-D 와 OCT 를이용한초기인공우식병소의변화탐지 구혜민 1,2,3, 김보라 1,2,3, 강시묵 1,2,3, 정중호 4, 권호근 1, 김백일 1,2,3 1 연세대학교치과대학예방치과학교실, 2 BK21 플러스통합구강생명과학사업단, 3 구강과학연구소, 4 LG 전자미래 IT 융합연구소 Detection of early changes in caries lesion using QLF-D and OCT Hye-Min Ku 1,2,3, Bo-Ra Kim 1,2,3, Si-Mook Kang 1,2,3, Jung-Ho Chung 4, Ho-Keun Kwon 1, Baek-Il Kim 1,2,3 1 Department of Preventive Dentistry & Public Oral Health, 2 BK21 PLUS Project, 3 Oral Science Research Center, Yonsei University College of Dentistry, 4 Future IT R&D Laboratory, LG Electronics, Seoul, Korea Received: March 19, 2014 Revised: March 19, 2014 Accepted: March 26, 2014 Corresponding Author: Baek-Il Kim Department of Preventive Dentistry & Public Oral Health, Yonsei University College of Dentistry, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752, Korea Tel: +82-2-2228-3070 Fax: +82-2-392-2926 E-mail: drkbi@yuhs.ac * 이연구는 LG 전자의지원을받아수행되었음 (No. C2013014770). Objectives: We aimed to compare the differences in caries lesion changes when measured by QLF-D as fluorescence loss and by SS-OCT as lesion depth with respect to demineralized time, during formation of artificial early caries lesion. We also demonstrated that QLF-D and SS-OCT can be used effectively in monitoring the longitudinal progression of simulated caries lesions. Methods: Ten bovine incisors were sectioned (5 4 mm) and embedded in epoxy resin. An acidresistant nail varnish was applied to a part of the tooth surfaces to protect sound enamel (2 4 mm). To generate lesions, each specimen was immersed in 40 ml of a demineralizing gel for 20 days at 37 o C. To measure mineral loss of the demineralized specimens, fluorescence loss ( F, %) was measured by QLF-D and lesion depth (μm) was determined by SS-OCT from the captured cross-sectional image. All the specimens were analyzed daily by QLF-D image analysis software and SS-OCT image analysis program for 20 days. The repeated measures analysis of F and lesion depth was used. The paired t-test was used to assess differences between each day. The correlation between F and lesion depth was determined using the Pearson s correlation coefficient. Results: On the 5th, 10th, and 15th day, compared to baseline values, F decreased in 12.7%, 25.0%, and 33.6% of the specimens, respectively, and the lesion depth increased in 9.9%, 16.0%, and 22.6% of the specimens, respectively. However, after 15 days, there was no change in the F and lesion depth. High significant correlation was identified between the resultant values of F obtained by QLF-D and those of lesion depth obtained by SS-OCT (r = 0.811, P<0.0001). Conclusions: The QLF-D and SS-OCT could detect subtle changes in mineral loss and lesion depth with respect to demineralized time. Furthermore, these devices were useful for monitoring changes in mineral amount and lesion depth. Key Words: Early dental caries, Longitudinal study, Optical coherence tomography, Quantitative light-induced fluorescence-digital 서론 우리나라는국민의 DMFT 지수감소, 소득수준증가및 Dental IQ 상승등다양한요인에따라예방적치과치료에대한 환자의요구가증가하기시작했다. 일반적인만성질환과마찬가지로치아우식증의성공적인예방을위해서는초기의미세한변화를탐지하여적절한치료를제공하는것이중요하다 1). X-ray는시진과함께현재가장널리쓰이고있는우식탐지 Copyright 2014 by Journal of Korean Academy of Oral Health This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.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. JKAOH is available at http://www.jkaoh.org pissn 1225-388X / eissn 2093-7784

11 구혜민외 QLF-D와 OCT를이용한초기인공우식병소의변화탐지 방법으로현재대다수임상가는방사선사진상에서나타난우식의진행정도로개인의치아우식증을진단하고있다 2). 그러나방사선사진은법랑질의 1/2 이상우식이진행되어야비로소확인이가능하므로민감도가낮고실제병소의깊이보다과소평가될가능성이높아초기단계의우식을탐지하기에는많은제한점이있다고알려져있다 3). 이처럼기존의우식탐지방법은주로진행된우식병소탐지에초점이맞춰져있으므로초기우식병소를탐지하기가매우어렵다 4). 최근몇년간새로운우식탐지장비에대한관심이증가하여초기에탈회된치아의미세한변화를측정할수있는우식탐지기기들이새롭게개발되고있다. 새로운우식탐지장비는주로 X-ray, 빛, 전류, 초음파및표면의거칠기등의다양한물리적성질을대리변수로이용하며치아구조의미세변화를이들대리변수의변화로반영하여나타내고있다 5). 이처럼물리적성질을이용하는탐지장비는우식이진행된상태와정상상태를비교하여미세한변화를탐지할수있고임상가의진단에유용한정보를제공할수있다 5). 치아에서발생하는초기무기질변화를탐지하는장비로잘알려진 Quantitative light-induced fluorescence (QLF) 는 405 nm 파장의푸른색가시광선에의해유도되는치아의자가형광성을이용하여탈회가발생한부위의형광소실도를정량적으로분석이가능한소프트웨어가탑재된구내카메라장비로처음소개되었다. 초기우식진단장비에대한체계적문헌고찰을통해다른우식진단기기와비교했을때 QLF는민감도 0.83, 특이도 0.92로초기우식을탐지하는데효과적임이보고된바있다 6-10). 또한많은선행연구를통하여비침습적인이장비가장기간초기우식증의변화양상추적에유용함이밝혀졌다 7,11). QLF는최근에전악촬영이가능한디지털카메라와특수필터를사용한새로운형태인 Quantitative light-induced fluorescence-digital (QLF- D) 로발전되었다 (Fig. 1). QLF-D 는기존의 QLF와같이우식의 진행정도를형광소실의변화로분석하는원리는동일하지만필터를개선하여치아본연의색에보다가깝게보인다는장점이있어임상에서유용하게활용될수있다 7). 한편비파괴적으로인체조직의단층영상을얻을수있는광결맞음영상장치 (Optical coherence tomography, OCT) 라는새로운기술이개발되었고현재치의학분야에서초기우식증의진단장비로서의활용가능성이연구되고있다 12-15). OCT는안과영역의망막검사에활발히이용되고있던기술로근적외선영역파장대 (1260-1360 nm) 의광원을사용하여생체조직에산란현상이적게일어나고깊은투과깊이를얻을수있다. 최근에는치의학분야에서이러한 OCT의원리를이용하여치아조직표면에빛을조사함으로써횡단면의영상을비침습적으로얻고자노력하고있다. 선행연구결과에따르면 OCT의횡단면영상을이용했을때치아의평활면우식진행단계를평가하기에시진보다높은민감도와특이도를나타냈으며숙련된검사자간일치도가 0.78로높게보고된바있다 16). 이에따라 OCT는치아우식증의진행정도를결정하는또하나의탐지도구로써활용가능성이높을것으로예상된다. 현재사용되고있는 OCT는물체의스캐닝방법에따라시간영역의 OCT (time domain OCT) 와스펙트럼영역의 OCT (spectral domain OCT) 로나눌수있다. 스펙트럼영역의 OCT 는시간영역의 OCT보다조직의횡단면이미지를획득하는데있어서측정시간이빠를뿐만아니라신호대잡음비가높은장점을가지고있다 17,18). 또한스펙트럼영역 OCT는스캐닝방법에따라분광형광결맞음영상장치 (spectral domain OCT, SD-OCT) 와이것이변형된고속의파장변환광원을이용한파장변환광결맞음영상장치 (swept-source OCT, SS-OCT, Fig. 2) 로분류될수있다. 법랑질의무기질소실량을 OCT로측정한대부분의연구들은시간영역스캐닝방식인 OCT (time domain OCT) 나 SD-OCT 연구에국한되어있고 SS-OCT를이용한우식병소변 Fig. 1. An image showing analysis of specimen and QLF-D device a (A). Fig. 2. An image showing scanned specimen and SS-OCT device a (B).

12 J Korean Acad Oral Health 2014;38:10-16 화추적에대한연구는거의없다 19). 따라서시간에따른초기우식병소의변화양상을비파괴적진단장비인 SS-OCT로탐지하고이를추적할수있는지확인하는것이필요하다. 이를통해, 우식와동의형성전단계인초기우식병소의발생과미세한변화과정을탐지할수있는지여부를확인한다면예방적치료계획수립의근거를마련하는데도움이될것이다. 이에본연구에서는탈회시간에따른우식병소의미세변화를형광소실량의변화로나타내는 QLF-D 와광간섭변화를영상화할수있는 SS-OCT의비교를통해비파괴적으로우식병소의탐지및추적이가능한지확인하고자하였다. (Prototype, LG electronics, Seoul, South Korea) 를사용하여 20일동안매일횡단면의이미지를스캐닝한후사진을촬영하였다. 병소의깊이는 SS-OCT로스캔한횡단면이미지를이미지분석프로그램 (Image Pro-Plus 6.0; Media cybernetics, Washington, D.C., USA) 을이용하여탈회로인해빛이산란되어건전치질과다른색을나타내는부분을우식병소로제한하여병소의깊이 (μm) 를측정하였다. QLF-D 와 OCT를이용하여이미지를촬영및분석하는것은한명의검사자가실행하였으며, 한시편의탈회부위에서세부위의깊이를측정하였다. 연구대상및방법 1. 시편준비및인공우식병소형성건전한우전치법랑질순면을 5 4 mm 크기로다이아몬드 디스크 (Superflex 358; NTI-Kahla GmbH, Kahla, Germany) 가장착된저속핸드피스 (Lasungmedice, Seoul, South Korea) 를이용하여절단하였다. 10 개의절단된우치를법랑질표면이 노출되도록 20 11 7 mm 크기의아크릴몰드에레진 (Jet TM Tooth Shade; Lang Dental MFG. Inc., Wheeling, IL, USA) 으로매몰한후 P800, P1500, P2400 의연마지 (Sic sand paper, R&B Inc., South Korea) 를이용하여단계적으로편평하게연마 하였다. 연마된법랑질시편표면의 2 4 mm 면적에내산성의 바니쉬를도포하여정상법랑질을보호하였고, 나머지 3 4 mm 는탈회용액에노출하여인공우식병소가형성되도록준비하였 다. 인공우식병소형성을위해 1 M lactic acid 에 Carbopol 2050 (Carbopol ETD 2050 polymer; Noveon, Ohio, USA) 이 1% 포함된 ph 4.8 의탈회용액을제조한후, 각시편 1 개당 40 ml 의 탈회용액에개별로침적시켜 37 o C 에서 20 일동안탈회시켰다. 2. 인공우식병소의형광소실량및병소깊이평가 2.1. QLF-D 를이용한탈회병소의형광소실량측정본연구에서는 Digital full-sensor SLR camera (Model 550D, Canon, Tokyo, Japan) 에청색광과백색광의 LED 가카메 라본체앞에장착된 QLF-D system (Biluminator TM, Inspektor research systems BV, Amsterdam, The Netherlands) 을사용 하였다. 촬영조건은 shutter speed 1/20 s, aperture value 7.1, ISO speed 1600 으로고정하여 Live view 방식으로 20 일동안 탈회된시편표면의형광사진을매일반복촬영하였다. 탈회된시 편의형광소실량은청색광원에서촬영한형광이미지에서건전치 면대비형광소실량을나타내는 F(%) 를 QLF-D 전용분석프로 그램 (QA2 v 1.23; Inspektor research systems BV, The Netherlands) 을이용하여측정하였다. 2.2. SS-OCT 를이용한탈회병소의깊이측정우식병소의깊이를측정하기위하여중앙파장 1310 nm, 대 역폭 100 nm, 파장변환속도 50-kHz 의광원을이용한 SS-OCT 3. 통계분석시간에따른병소의변화양상의유의성은반복측정분산분석 으로검정하였고, 각탈회시간에따른형광소실량과병소깊이 가나타내는전후차이는대응표본 t- 검정으로분석하였다. 우식 병소의변화를탐지하는 QLF-D 와 SS-OCT 간의관련성은피어 슨상관분석 (Pearson correlation coefficient) 으로확인하였다. 모든통계분석은 PASW 18.0 통계패키지프로그램 (SPSS Inc., Chicago, IL, USA) 을이용하여유의수준 0.05 에서수행하였다. 연구성적 1. QLF-D 를이용한인공우식병소의형광소실량변화평가 QLF 를이용하여인공우식병소의형광소실량 ( F) 을 20 일 동안추적관찰한결과, F 은 1 일차인 0.5% 부터 20 일차인 33.6% 까지감소함을나타내었다 (P<0.0001, Table 1). F 는탈회 2 일차에 9.2% 로가장큰감소율을나타내었다. 또한, 1 일차측정값과비교하면 5 일, 10 일, 15 일, 20 일차형광소실 률은각각 12.3%, 48.2%, 60.0%, 65.0% 로점차증가하였다 (P<0.0001). 전체적으로탈회시간이증가함에따라우식병소 에서 F 가감소하는변화양상을볼수있었으나, 15 일이후부터 F 값이거의일정하게유지되는것을볼수있었으며형광이미지 상에서크게변화되지않음을보였다 (Fig. 3). 2. SS-OCT 를이용한인공우식병소의깊이변화평가탈회시간이증가함에따라우식병소깊이는 1 일차부 터 20 일차까지 65.7 μm 에서 289.1 μm 로점차증가하였다 (P<0.0001, Table 1). 1 일차측정값보다 5 일, 10 일, 15 일, 20 일 차병소깊이는각각 2.5 배, 3.5 배, 4.4 배, 4.4 배증가하는것으로 나타났다 (P<0.0001). 인공탈회병소의깊이는탈회용액에침적 시킨후 1 일차에 65.7% 로가장큰변화를나타냈고탈회 15 일차 까지는증가하는양상을보이다가, 16 일이후에는불규칙적인변 화를나타냈으며횡단면이미지에서도병소깊이의뚜렷한변화 가나타나지않았다 (Fig. 4).

13 구혜민외 QLF-D와 OCT를이용한초기인공우식병소의변화탐지 Table 1. Changes in fluorescence and lesion depth by demineralization time Days 1 st 2 nd 3 th 4 th 5 th 6 th 7 th 8 th 9 th 10 th 11 th 12 th 13 th 14 th 15 th 16 th 17 th 18 th 19 th 20 th P-value* <0.0001 289.1 (23.1) 288.2 (22.4) 295.2 (23.5) 300.6 (23.8) 311.3 (29.2) 291.2 (22.4) 263.7 (11.1) 268.7 (11.1) 250.0 (23.9) 241.0 (15.4) 232.4 (23.8) 239.9 (15.5) 202.9 (23.0) 203.0 (27.4) 181.2 (29.3) 164.9 (25.3) 139.0 (17.4) 117.8 (21.0) 97.0 (17.9) LD 65.7 (17.2) P-value 0.001 0.006 0.002 <0.001 0.019 <0.001 0.992 0.003 0.501 0.200 0.201 0.040 0.685 0.001 0.036 0.268 0.493 0.288 0.923 <0.0001 33.6 (4.5) 32.6 31.6 (6.6) 31.6 (4.4) 29.9 (4.2) 31.1 (4.5) 30.7 29.7 (5.0) 28.3 26.8 (4.0) 25.1 (5.2) 23.7 22.6 (4.4) 21.0 (4.4) 16.7 (3.3) 12.8 (2.3) 10.1 (2.5) 7.4 (1.4) 5.2 (1.9) F 0.5 (1.6) P-value <0.001 0.003 0.001 <0.001 <0.001 <0.001 0.001 <0.001 0.007 0.009 0.004 <0.001 0.025 0.198 0.009 0.001 0.983 0.277 0.008 All values are the mean (standard deviation). F means the loss of fluorescence in demineralized enamel part compared to sound part (%). LD means the lesion depth measured in images taken by SS-OCT (mm). *P-values denote statistically significant differences within rows by repeated measures analysis. P-values denote statistically significant differences by paired t-test. 3. QLF-D 로측정한형광소실량과 SS-OCT 로측정한병소깊이와의관련성 20 일탈회시키는동안시간에따른인공우식병소의변화를 SS-OCT 로측정한병소깊이와 QLF-D 로측정한형광소실량은 높은음의상관성을나타냈고이는통계적으로유의미하였다 (r = 0.811, P<0.0001). 고안 본연구에서는 QLF-D 와 SS-OCT 를이용하여인공우식병소 를형성하는과정중에탈회시간에따라치아에서나타나는미세 한변화를탐지및추적할수있는지를평가하고자하였다. 본연 구에서 QLF-D 로관찰한탈회병소의 F 값은 14 일차까지통계 적으로유의하게감소하였고, 푸른광원하에촬영한이미지를육 안으로보아도인공우식병소를형성한시간에따라형광이소실 된정도가증가함을확인할수있었다 (P<0.0001, Table 1, Fig. 3). 반면 SS-OCT 로측정한병소깊이는전체적으로 20 일까지 는증가하는추세를보였으나, 탈회 9 일차까지만매일약 21.8% 씩통계적으로유의하게증가하는양상을보였고그이후에는증 가율이점차감소하였으며통계적으로도유의하지않았다 (Table 1). 이결과에따르면 SS-OCT 를이용한병소깊이변화만으로 초기병소의진행정도를판단하는데어느정도의한계가있으며, 이대신병소에서발생한무기질의변화를 QLF-D 를이용하여형 광소실정도로측정하는것이조금더민감하게병소의변화를탐 지하고추적해낼수있는것으로사료된다. 다만, 15 일이후에형 성된인공우식병소에서 QLF-D 에의한형광소실량과 SS-OCT 에의한병소깊이모두크게변화하지않았다. 이는탈회 20 일까 지제한된용량의탈회용액을사용하여지속적으로법랑질을탈 회시켰기때문에법랑질과탈회용액간의산이온의움직임이더 이상진행되지않고포화되어더이상탈회가진행되지않아두장 비모두에서변화를탐지하기어려웠던것으로사료된다. 본연구에서사용한 QLF-D 는기존의 QLF 와형광을이용한 다는기본원리는동일하다. QLF 는파괴적인방법으로치질의무 기질변화를평가하는대신에비파괴적인평가방법인형광소실 량으로치질의미세변화를나타내는탐지능력에대한민감도는 0.98, 특이도 0.95 으로타당성이우수한장비임은이미입증되었 다 20). QLF 를이용하여우식병소진행과정을장기적으로추적 한선행연구결과들은 QLF 가탐지장비로서타당한지증명하기 위해파괴적으로절단하여무기질소실량을정량적으로측정하는 transverse microradiography (TMR) 와비교하였고그결과 0.8 이상으로높은상관성을나타내었다 6,21). 그러나본연구에서는동 일한시편을 TMR 로측정하지않았기때문에 QLF-D 의형광소 실량과직접적으로비교할수는없었지만, QLF 와동일한원리이 므로실제무기질소실량을유사하게반영했을것으로예상된다. 이에따라 QLF-D 도초기미세한변화를민감하게탐지할수있 을것으로사료된다. 또한 QLF 의타당성이입증되면서초기교합 면우식병소의 F 값에따라적절한치료방법을분류한선행연

14 J Korean Acad Oral Health 2014;38:10-16 Fig. 3. Images taken by blue light of QLF-D over demineralization time. (A) base line, (B) day 1, (C) day 5, (D) day 10, (E) day 15, and (F) day 20. In the image, a left arrow indicates the sound area and a right arrow shows the demineralized area of the photographed specimen. Fig. 4. Images taken by SS-OCT over demineralization time. (A) base line, (B) day 1, (C) day 5, (D) day 10, (E) day 15, and (F) day 20. In the image, a left arrow indicates the sound area and a right arrow shows the demineralized area of the scanned specimen. 구결과에따르면임상가가수복치료를행하기모호한환자의우식을진단할경우정량적인수치인 F 값을제시할수있다 22). 이를통해진단과정에도움을줄수있을뿐만아니라환자를위한최소한의침습적인처치를제공할수있을것으로예상된다. 또한, QLF-D 는장기적으로초기의탈회를정량화하고추적할수있어환자가정기적으로치과에내원했을때육안으로보이지않고증상이없는초기우식치아의변화양상을 QLF-D 로촬영하여환자에게보여줄수있다. 따라서초기우식증환자에서형광이소실되어밝기가감소된치아의사진과분석을통해우식진전도에따른예방적처치를받아더는우식이진행되지않도록관리할수있을것이다. 한편본연구에서는 SS-OCT를이용하여건전부분에대비한상대적인병소깊이의변화를측정하였다. SS-OCT는반사되거나투과된광자와산란된광자의차이를이용하여조직내부구조의횡단면이미지를획득할수있다. 선행연구에따르면 SS-OCT 는광원의특성상투과깊이에제한을받기때문에깊은생체조직의영상을획득할수없다는단점이있다고보고되었다 23). 이와유사하게본연구에서도 9일이상탈회된병소의경우무기질소실에따른변화를민감하게확인할수없었다. 하지만치아조직의 Dentine-enamel junction (DEJ) 까지는확인이가능하였고상아질의일부분도탐지가가능하기때문에수복치료의상태확인에도이용가능할것으로예상된다. SS-OCT를이용하여촬영한이미지를정확하게분석하기위해서는치아경조직의광학적특성을이해할필요가있다 16,23). 선행연구에따르면 QLF-D 와 SS-OCT는빛을이용하여치아구조의변화를탐지하는장비이기때문에탈회된조직내에남아있는타액으로인하여굴절률이증가할경우건전법랑질과탈회법랑질간의경계가모호해질수있다고보고된바있다 24). 공기의굴절률이 1.00일때물은 1.33, 건전법랑질의굴절률은 1.63이지만 탈회로인한병소본체의무기질소실때문에법랑질조직내에 2 개의다른굴절지수가나타날수있다. 이를통해탈회된무기질결정체와 pore 내액체간의미세계면에서높은반사가나타날가능성이크다 24). 따라서건전치면과탈회된치면을 QLF-D 와 SS- OCT로촬영했을때이미지의밝기강도가다르게나타난다. 그러나실제구강내환경은항상타액에젖어있는상태이므로치아를완전하게건조시키지않는다면정확한탐지가어려울수있다. 그러므로임상현장에서두탐지기기를이용해정확한진단을하기위해서는치아를완전히건조시킨후촬영해야할것으로예상된다. SS-OCT로측정한병소깊이는 1일차탈회이미지에서밝기가확연히다르게나타나는부분을볼수있었으며이때의병소깊이는 65.7 μm로측정되었다. 본연구와동일한방법으로인공우식병소를형성한선행연구에따르면 1일동안탈회된병소를절단하여편광현미경으로측정한실제병소의깊이는약 40 μm 를나타낸것으로보고되었다 25). 이와비교하였을때본연구에서 SS-OCT로측정한병소깊이는실제깊이보다과대측정된것으로보인다. 조직의굴절지수에관한 OCT 연구에따르면 OCT의단층영상은표면과조직을통과하는광학거리에영향을받기때문에화면상의 OCT 이미지에서보이는치아의깊이는실제깊이보다 1.63배확대되어보인다고보고된바있다 23). 따라서본연구에서도 1일차에상대적인탈회깊이측정시실제보다확대되어보였던것으로사료된다. 이렇게확대되어보여지는 SS-OCT 이미지를해석할때검사자의주관적인기준점이크게영향을미칠수있으므로과대평가하지않도록주의할필요가있다. 한편일반적으로편광현미경이나공초점레이저현미경을이용한병소의깊이측정시, 한명의검사자가병소의변화부위를확인하고동일한기준으로병소깊이를측정한다 25). 또한측정상의오차를최소화하기위해임의로세지점이상을측정하여이들의평균값을

15 구혜민외 QLF-D와 OCT를이용한초기인공우식병소의변화탐지 병소깊이로제시한다. 이에따라본연구에서도 OCT 로촬영한 이미지내에서색이변화된지점을정하였고한시편당세부위의 깊이를측정하였다. 그러나 SS-OCT 를이용하여관찰하는상은 물질의굴절률에따라변할수있기때문에병소의정확한깊이를 반영하지못하는한계가있으므로무기질소실에따른굴절률을 고려해야한다. 따라서추후연구를통해인공우식병소를형성하 는시간에따라매번시편을절단하여병소의실제깊이를측정하 고이와 SS-OCT 로측정한상의깊이와의관련성을파악할필요 가있다. 이와더불어본연구에서이용한 SS-OCT 는아직상품 화되지않은시제품 (prototype) 이므로치질의미세한변화를정 확히탐지하는것에대한여부는다시검증해야할필요가있다. 본연구에서는 SS-OCT 로획득한횡단면이미지를치아의무 기질이소실된부위와건전부위를비교함으로써상대적인병소 깊이를측정하고변화양상을확인할수있었다. 따라서 SS-OCT 를통해탈회초기의미세한변화를실시간으로탐지및추적할수 있음을확인하였다. 본연구를통해두탐지장비가초기의미세한변화를탐지할 수있고이를정량적으로수치화할수있다는점은객관적인근거 중심에기반을둔진단과정이라고말할수있다. 향후임상현장에 서탐지도구로서사용할 QLF-D 와 SS-OCT 는실시간으로촬영 이가능하므로임상에서초기우식병소를탐지하고지속적으로 추적관찰하는데유용할것이다. 결론 탈회시간에따른인공우식병소형성을 QLF-D 와 SS-OCT 를 이용하여탐지및추적할수있는지평가한결과다음과같은결론 을얻었다. 1. QLF-D 로측정한탈회병소의 F 값은 14 일차까지감소하 였고 (P<0.0001), 푸른광원하에촬영한이미지를육안으로보 아도인공우식병소를형성한시간에따라형광이소실된정도가 증가함을확인할수있었다. 2. SS-OCT 로측정한병소깊이는전체적으로 20 일까지는증 가하는추세를보였으나, 탈회 9 일차까지만매일약 21.8% 씩통 계적으로유의하게증가하였다. 또한 SS-OCT 로촬영한이미지 를육안으로보아도시간에따른변화양상이점차증가함을확인 할수있었다. QLF-D 를통한형광소실량과 SS-OCT 를이용한병소깊이 모두인공우식병소형성초기에법랑질의미세한변화를측정할 수있었다. 참고문헌 1. Kim CS, Han SY, Kim CW. The relationship between regional socioeconomic position and oral health behavior: A multilevel approach analysis. J Korean Acad Oral Health 2013; 37:208-215. 2. Ricketts DN, Kidd EA, Smith BG, Wilson RF. Clinical and radiographic diagnosis of occlusal caries: a study in vitro. J Oral Rehabil 1995;22:15-20. 3. Haak R, Wicht MJ, Hellmich M, Gossmann A, Noack MJ. The validity of proximal caries detection using magnifying visual aids. Caries Res 2002;36:249-255. 4. Bader JD, Shugars DA, Bonito AJ. Systematic reviews of selected dental caries diagnostic and management methods. J Dent Educ 2001;65:960-968. 5. Pretty IA. Caries detection and diagnosis: novel technologies. J Dent 2006;34:727-739. 6. Gmur R, Giertsen E, van der Veen MH, de Josselin de Jong E, ten Cate JM, Guggenheim B. In vitro quantitative light-induced fluorescence to measure changes in enamel mineralization. Clin Oral Investig 2006;10:187-195. 7. Stookey GK. Quantitative light fluorescence: a technology for early monitoring of the caries process. Dent Clin North Am 2005;49: 753-770, vi. 8. Pretty IA, Pender N, Edgar WM, Higham SM. The in vitro detection of early enamel de- and re-mineralization adjacent to bonded orthodontic cleats using quantitative light-induced fluorescence. Eur J Orthod 2003;25:217-223. 9. Ando M, Hall AF, Eckert GJ, Schemehorn BR, Analoui M, Stookey GK. Relative ability of laser fluorescence techniques to quantitate early mineral loss in vitro. Caries Res 1997;31:125-131. 10. Gomez J, Tellez M, Pretty I, Ellwood R, Ismail A. Non-cavitated carious lesions detection methods: a systematic review. Community Dent Oral Epidemiol 2013;41:55-66. 11. Chew HP, Zakian CM, Pretty IA, Ellwood RP. Measuring initial enamel erosion with quantitative light-induced fluorescence and optical coherence tomography: an in vitro validation study. Caries Res 2014;48:254-262. 12. Natsume Y, Nakashima S, Sadr A, Shimada Y, Tagami J, Sumi Y. Estimation of lesion progress in artificial root caries by swept source optical coherence tomography in comparison to transverse microradiography. J Biomed Opt 2011;16:071408. 13. Amaechi BT, Podoleanu A, Higham SM, Jackson DA. Correlation of quantitative light-induced fluorescence and optical coherence tomography applied for detection and quantification of early dental caries. J Biomed Opt 2003;8:642-647. 14. Jones RS, Darling CL, Featherstone JD, Fried D. Imaging artificial caries on the occlusal surfaces with polarization-sensitive optical coherence tomography. Caries Res 2006;40:81-89. 15. Shimada Y, Sadr A, Burrow MF, Tagami J, Ozawa N, Sumi Y. Validation of swept-source optical coherence tomography (SS-OCT) for the diagnosis of occlusal caries. J Dent 2010;38:655-665. 16. Nakagawa H, Sadr A, Shimada Y, Tagami J, Sumi Y. Validation of swept source optical coherence tomography (SS-OCT) for the diagnosis of smooth surface caries in vitro. J Dent 2013;41:80-89. 17. Lim H, de Boer JF, Park BH, Lee EC, Yelin R, Yun SH. Optical frequency domain imaging with a rapidly swept laser in the 815-870 nm range. Opt Express 2006;14:5937-5944. 18. Chinn SR, Swanson EA, Fujimoto JG. Optical coherence tomography using a frequency-tunable optical source. Opt Lett 1997;22: 340-342. 19. Fried D, Xie J, Shafi S, Featherstone JD, Breunig TM, Le C. Imaging caries lesions and lesion progression with polarization sensitive optical coherence tomography. J Biomed Opt 2002;7:618-627. 20. Gomez J, Zakian C, Salsone S, Pinto SC, Taylor A, Pretty IA, et al. In vitro performance of different methods in detecting occlusal caries lesions. J Dent 2013;41:180-186. 21. Pretty IA, Ingram GS, Agalamanyi EA, Edgar WM, Higham SM. The use of fluorescein-enhanced quantitative light-induced fluorescence to monitor de- and re-mineralization of in vitro root caries. J Oral Rehabil 2003;30:1151-1156.

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