Journal of Dental Hygiene Science Vol. 11, No. 5, pp. 445~453 (2011) 불소함유교정용레진시멘트의불소유리및법랑질탈회저항성에대한효과 김명은 강재경 1 김수화 2 이민영 3 이주혜 4 김형식 4 김광만 4 대원대학치위생과, 1 신구대학교치위생과, 2 한양여자대학치위생과, 3 영동대학교치위생학과, 4 연세대학교치과대학치과생체재료공학교실 The Effect of Orthodontic Resin Cements Containing Fluoride on Fluoride-releasing and the Resistance to Enamel Decalcification Myung-Eun Kim, Jae-Kyoung Kang 1, Soo-Wha Kim 2, Min-Young Lee 3, Joo-Hye Lee 4, Hyoung-Sik Kim 4 and Kwang-Mahn Kim 4 Department of Dental hygiene, Daewon University College, Jecheon 390-702, Korea 1 Department of Dental hygiene, Shingu University, Sungnam 462-743, Korea 2 Department of Dental hygiene, Hanyang Women's University, Seoul 133-793, Korea 3 Department of Dental hygiene, Youngdong University, Yongdong-gun 370-701, Korea 4 Department and Research Institute of Dental Biomaterials and Bioengineering, Yonsei University College of Dentistry, Seoul 120-752, Korea Abstract Objectives : The purpose of this study was to determine of fluoride-releasing of orthodontic resin cements containing fluoride and compare of tooth attached fluoride and non-fluoride resin cements. Methods : Total eighty premolar tooth were used in this study. Forty tooth were used for fluoride releasing measurement and forty tooth were used for measurement. Each forty tooth were randomly divided into four groups, and brackets were attached on tooth surface with Blugloo, Light Bond, Orthofolw(experimental groups) and Transbond cement(control group). After brackets were attached on tooth surface, forty tooth were immersed in artificial salival and then the quantity of fluoride releasing was measured ever day for 8days and then three-days intervals for 3 weeks. Forty tooth were immersed in solution for 48hours and then degree of was measured as lesion area, F, and Q using QLF. The data were analysed by one-way ANOVA and Pearson's correlation coefficient using SPSS 12.0 program. Results : Fluoride release of experimental groups was higher than control group(p<0.05). Cumulative fluoride release of experimental groups was also higher than control group(p<0.05). There were the highest release during first day. F, and Q was high TB > BG > OF > LB (p<0.05). Change of F, and Q was also high TB > BG > OF > LB (p<0.05). As for correlation between fluoride release and lesion area, F, and Q showed negative correlation but there was no significant difference. Conclusions : This study shows that orthodontic reins cements containing fluoride release fluoride and prevent initial enamel caused by orthodontic treatment. Key words Decalcification, Fluoride releasing, Orthodontic resin cement 서 론 치아우식증은치아의경조직에서발생되는질환이다. 일반적으로소아나청소년층에서우식유발식품의섭취빈도가높고구강위생관리능력이낮아우식발생률이높은것으로알려져있다. 또한치아교정을위해장기간 Corresponding author Tel: 02-2228-3082 Fax: 02-364-9961 E-mail: kmkim@yuhs.ac 교정장치를장착하게되는경우에도치아우식증의발생률이증가하는데, 특히가철성교정장치보다고정성장치의경우치아의평활면탈회에영향을줄수있다 1,2). 이에고정성교정장치를장착하는동안브라켓주변에서발생하는치아탈회정도를낮추고자하는노력으로불소로양치하는방법 3) 이나국소적으로불소를도포하는방법들이제시되어왔고 4) 불소를유리하는시멘트를개발하여임상적으로사용해왔다 5,6). Basdra 등 7) 은불소를포함한시멘트와불소를포함하지않은시멘트를이용하여브라켓을장착한후불소의유리정도와법랑질의탈회를 445
446 The Effect of Orthodontic Resin Cements Containing Fluoride on Fluoride-releasing and... 평가하고, 법랑질표면의변화를관찰하였다. 실험결과불소를포함한시멘트를사용하여부착한브라켓주변의법랑질탈회가더낮았으며법랑질표면에는불화칼슘이미세구모양으로침착되었다고보고하였다. Sonis 와 Shell 8) 도불소를포함한교정용접착제와그렇지않은접착제의탈회유병율을측정한결과불소를포함한교정용접착제에서탈회유병율이낮았다고보고하였다. Pascotto 등 9) 은글래스아이오노머를이용하여브라켓을부착한후, 대조군과비교한결과법랑질탈회에있어서글래스아이오노머를이용한실험군이좀더효과적이었다고보고하면서글래스아이오노머가교정용브라켓주변의치아우식발생을감소시킬것이라고주장하였다. 이와더불어교정용복합레진에불소를첨가하는노력도이루어졌는데 10,11), Wiltshire 와 van Rensburg 12) 는불소를유리하는교정용레진의불소유리정도를측정하였고, 브라켓부착후 85 주까지계속해서불소가유리되었음을보고하였다. Cohen 등 13) 은개량형재료들인레진강화형글래스아이오노머와콤포머의불소유리를 30 개월동안측정한결과불소를포함하지않은레진에비하여많은양의불소를유리하였고, 백색병소의형성을줄일수있을만큼의장기간불소를유리한다고보고하였다. Wilson 과 Donly 14) 도불소를포함한복합레진과레진강화형글래스아이오노머의불소유리와브라켓주변의법랑질탈회를측정한연구에서두재료에서모두불소가유리되었고, 불소를포함한그룹이포함하지않은그룹에비해법랑질탈회가적었다고하였으며, 불소를포함한복합레진과레진강화형글래스아이오노머간의차이는없다고보고하였다. 그러나 Ghani 등 15) 은불소함유레진은장기간의불소유리를나타내지못하며단기간에서도극소량의불소가유리된다고하였으며, Fox 16) 도불소함유레진은매우소량의불소를유리하며이는항우식효과를갖지않는다고하였다. 이는 Moura 등 17) 의연구결과와일치하는데, 레진강화형글래스아이오노머이장재와복합레진이장재에서방출되는불소의양에는통계적으로유의한차이를보였으나치질의탈회저항성에서는유의한차이를나타내지 않았다고하였다. 이에본연구는불소를포함한교정용레진시멘트와불소를포함하지않은교정용레진시멘트의불소유리량과이에따른치아의탈회정도를 QLF TM (Inspektor dental care bv, Netherlands) 장비를사용하여측정해보고자하였다. 연구재료및방법 1. 연구재료 1) 교정용레진시멘트본연구에서는 4가지군으로나누어실험을진행하였다. 실험군으로는불소를포함하고있는광중합형교정용레진시멘트인 Blugloo TM (Ormco Co., U.S.A), Light Bond (Relience Ortho Prod. Inc., U.S.A), Orthoflow(Vericom Co., LTD., Korea) 를선정하였고, 대조군으로는불소를포함하지않은광중합형교정용레진시멘트인 Transbond TM (3M Unitek, U.S.A.) 를선정하였다 (Table 1). 2) 브라켓실험에사용된브라켓은 Archist metal bracket 소구치용 (edgewise bracket.018, Daeseung Medical IND. Korea) 으로 80 개를이용하였다. 2. 연구방법 1) 시편의준비및창제작교정치료를위해최근에발거된소구치가운데형태적으로이상이없고손상이없으며치아우식에이환되지않은건전치아 45 개를선정하였다. 선정된치아는치아주변에붙어있는이물질을제거하여시편제작전까지증류수에보관하였다. 시편제작을위해치아의법랑백악경계부까지절제하여치관만을이용하였고, 치관을다시근원심방향으로절제하여협면과설면으로나누었다. 분할된치아는초음파세척기에넣어표면세척을하였으며이후거즈를깔고증류수에적셔브라켓부착전까지습윤을유지하였다. 본 Table 1. Materials used in this study Product Composition Type Code Manufacturer Lot No. DenFil Etchant-37 Etchant 37% Phosphoric acid gel Vericom, Korea Et950337 Control group Transbond Transbond TM XT paste LC, non F TB 3M, Unitek, USA N111537 Transbond TM MIP primer LC, non F 9LB Experimental Blugloo Blugloo LC, non F BG Ormco, USA 3277468 group Ortho solo contain F 2985250 Light bond Light bond adhesive paste LC, contain F LB Reliance, USA 0904707 Light bond sealant resin LC, contain F 0904661 Ortho flow Ortho flow LC, contain F OF Vericom, Korea FR940510S BC plus Non F BP951
Journal of Dental Hygiene Science Vol. 11, No. 5, pp. 445~453 (2011) 447 실험에서는 45 개의치아를근원심으로절제하여사용하였으며, 절제시파절등의손상이발생한치아를제외하고최종적으로 80 개의치아시편을준비하였다. 증류수에보관된치아를오일이첨가되지않은퍼미스 (Dentsply, USA) 로 30 초동안연마한후초음파로세척하고압축공기로건조시켰다. 이후불소의작용이브라켓주변부에만한정되도록시편의표면에창을제작하였다. 창의크기는실험에사용된브라켓사이즈 (3.7 mm 3.5 mm) 보다상하좌우로 1mm 씩더크게하였다 (5.7 mm 5.5 mm). 창의위치는치아의협설면중앙으로하였으며, 창을제외한나머지시편의표면에바니쉬를 2 회도포하고건조하여일정한측정면적을얻도록하였다. 준비된치아는불소유리량측정실험용 40 개와탈회저항성측정실험용 40 개로무작위분류하였고, 각 40 개의시편은다시레진시멘트별로 10 개씩으로무작위분류하였다. 2) 브라켓접착산부식에서건조과정까지는제조회사의지침에따라시행하였다. 이후브라켓위에레진을도포하여치면에부착하였다. 브라켓부착시브라켓중앙에 450 g 의균일한힘을 10 초간가하였다. 브라켓주변의잉여레진은탐침으로제거하였고, 광조사기 (S-Denti Co., Ltd., Korea) 를이용하여브라켓의근심과원심에각각 10 초씩총 20 초동안중합하였다. 3) 불소유리량측정불소유리량을측정하기위해개별적으로뚜껑이있는플라스틱시험관에 2 ml의인공타액 (Table 2) 을채우고브라켓이부착된시편을넣어뚜껑을닫고실온에보관하여시편속의불소가인공타액에유리용해되도록하였다. 시험관내인공타액은측정할때마다교환해주었다. Fluoride standard 100 ppm F - (940907, Thermo Fisher Scientific, Massachusetts, USA) 를 1ppm, 10 ppm으로희석하여표준을잡았다. 교정용레진시멘트에서의불소유리량을알아보기위해플라스틱시험관에 2 ml의인공타액을채우고시편을넣고실온에서보관하였다. 불소유리량의측정은시험을시작한다음날부터일주일동안 은매일측정하고, 이후로는 3 일간격으로 7 회측정하였다. 이온측정시인공타액 2 ml 와측정전시편의표면을세척한인공타액 1 ml 를혼합하고, 0.3 ml 의 TISAB (Thermo Fisher Scientific, Massachusetts, USA) 를혼합한다음불소이온전극봉 (Model 710A ph/ion meter, Thermo Fisher Scientific, Massachusetts, USA) 를이용하여불소이온농도를측정하였다. 불소이온농도측정후에는새로운인공타액으로교체해주었다. 4) 탈회저항성측정인위적으로초기우식병소를형성하기위해뚜껑이있는플라스틱시험관안에 2 ml의탈회용액 (ph 4.8)(Table 3) 을넣고, 브라켓을부착한시편을침적한후 37 o C의온도에서 48시간동안 100 rpm으로교반하였다. 이후시편을꺼내어수돗물로 3분세척하고, 증류수로 3분동안세척하였다. 탈회정도는 QLF TM (Inspektor dental care bv, Netherlands) 를이용하여 Q값 ( 무기질감소량 ), F값 ( 형광감소량 ), lesion area( 병소면적 ) 값으로측정되었다. QLF(Quantitative Light-induced Fluorescence) 촬영은브라켓부착전과탈회실험후각각시행하였다. 촬영전각시편은압축공기를이용하여 5초동안건조하였고, 촬영대중앙에위치시킨후촬영하였으며, 암실에서이루어졌다. 측정범위를브라켓주변으로한정시키기위해창의값과브라켓값의차를통계분석에이용하였다 (Fig. 1). 불소유리량과탈회저항성간의상관관계를알아보기위해, 2일째에해당하는누적불소량의값과탈회저항성측정실험의결과값 (lesion area, F, Q) 을이용하였다. Table 3. Composition of solution Composition Density(g/L) Ca(NO 3 ) 2 4H 2 O 0.4723 KH 2 PO 4 0.2722 CH 3 COOH 4.5083 Distilled water 1000 ml Table 2. Composition of artificial saliva 18,19) Composition Density(g/L) NaCl 0.40 KCl 0.40 CaCl 2 2H 2 0 0.795 NaH 2 PO 4 2H 2 0 0.780 Na 2 S 9H 2 0 0.005 CO(NH 2 ) 2 (Urea) 1.0 Distilled water 1000 ml Fig. 1. Windows area on tooth surface.
448 The Effect of Orthodontic Resin Cements Containing Fluoride on Fluoride-releasing and... 5. 통계처리각그룹별불소유리량과탈회저항성에대한그룹간의차이는 one-way ANOVA 와 Turkey's test 사후검정을시행하였으며, 불소유리량과탈회간의상관관계는 Pearson's correlation coefficient 로분석하였다. SPSS 12.0 통계프로그램을이용하였고, 모든통계적유의수준은 0.05 이다. 결 과 Fig. 2. Daily fluoride release. 1. 불소유리량본실험에사용된교정용레진의일별불소유리량과누적유리양은 Table 4, 5 와같다. 불소를포함한레진시멘트는불소를포함하지않은레진시멘트에비해불소유리량이통계적으로유의하게높았다 (p<0.05) BG 는측정첫날불소유리량이적었으나 (p<0.05) 3 일째부터증가하기시작하여 (p>0.05), 7 일째까지는다른그룹에비해유의하게많은양의불소를유리시켰으며 (p<0.05), 그이후에도꾸준하게불소를유리시켰다 (Table 4, Fig 2). 누적불소유리량역시불소를포함한레진시멘트가불소를포함하지않은레진시멘트에비해높은불소유리량을보였으나 (p<0.05), 불소를포함한레진시멘트군간에는유의한차이를보이지않았다 (Table 5, Fig. 3). 불소유리량의양상을보면측정첫날에가장많은불소를유리하였다 (p<0.05)(table 4, Fig. 2). 2. 탈회저항성측정 QLF 를이용하여교정용브라켓의부착전과부착후 Fig. 3. Cumulative fluoride release. 탈회과정을거친시편의 lesion area, F값, Q값은 Table 6과같다. 브라켓을부착하기전에측정한초기 lesion area, F값, Q값은그룹간의유의한차이가없었다 (p>0.05) (Table 6). 브라켓을부착한후 48시간동안탈회용액에침적한다음측정한각군의 lesion area, F값, Q값을측정한결 Table 4. Daily fluoride release (ppm) Day BG(Mean±SD) LB(Mean±SD) OF(Mean±SD) TB(Mean±SD) p-value 1 1.12±0.08 b1 1.40±0.35 a1 1.65±0.27 a1 0.44±0.02 c1 * 2 0.80±0.06 ab2 0.93±0.22 a2 0.78±0.66 b2 0.17±0.00 c2 * 3 0.70±0.11 a3 0.62±0.05 a3 0.64±0.06 a23 0.06±0.00 b3 * 4 0.69±0.06 a3 0.54±0.04 b34 0.51±0.08 b34 0.03±0.00 c4 * 5 0.68±0.07 a3 0.46±0.02 b34 0.36±0.02 c45 0.00±0.00 d5 * 6 0.59±0.06 a4 0.41±0.22 b45 0.35±0.02 c456 0.00±0.00 d5 * 7 0.44±0.05 a5 0.38±0.02 b45 0.32±0.04 c456 0.00±0.00 d5 * 8 0.37±0.02 a5 0.37±0.01 a45 0.29±0.02 b56 0.00±0.00 c5 * 11 0.37±0.05 a5 0.25±0.03 a56 0.58±0.29 b3 0.00±0.00 c5 * 14 0.26±0.02 a6 0.26±0.02 a56 0.18±0.02 b67 0.00±0.00 c5 * 17 0.13±0.01 a7 0.14±0.01 a67 0.10±0.02 b78 0.00±0.00 c5 * 20 0.10±0.02 a78 0.13±0.02 b67 0.06±0.01 c78 0.00±0.00 d5 * 23 0.04±0.01 a8 0.10±0.01 a67 0.03±0.01 b78 0.00±0.00 c5 * 26 0.00±0.00 a9 0.00±0.00 a8 0.00±0.00 a9 0.00±0.00 a5 29 0.00±0.00 a9 0.00±0.00 a8 0.00±0.00 a9 0.00±0.00 a5 p-value * * * * *p < 0.05 a-d The same letters in the same row indicate no significant different at α = 0.05 by Tukey's test 1-8 The same letters in the same column indicate no significant different at α = 0.05 by Tukey's test
Journal of Dental Hygiene Science Vol. 11, No. 5, pp. 445~453 (2011) 449 Table 5. Cumulative fluoride release (ppm) Day BG(Mean±SD) LB(Mean±SD) OF(Mean±SD) TB(Mean±SD) p-value 1 1.12±0.08 b 1.40±0.35 a 1.65±0.27 a 0.44±0.03 c * 2 1.92±0.12 b 2.33±0.34 a 2.43±0.26 a 0.61±0.03 c * 3 2.61±0.20 b 2.95±0.38 a 3.07±0.21 a 0.66±0.03 c * 4 3.31±0.24 a 3.49±0.39 a 3.58±0.20 a 0.69±0.03 c * 5 3.99±0.28 a 3.94±0.39 a 3.94±0.20 a 0.69±0.03 c * 6 4.58±0.33 a 4.36±0.39 a 4.29±0.21 a 0.69±0.03 c * 7 5.03±0.56 a 4.74±0.39 ab 4.61±0.22 b 0.69±0.03 c * 8 5.40±0.37 a 5.11±0.39 ab 4.90±0.23 b 0.69±0.03 c * 11 6.50±0.37 ab 5.87±0.36 a 6.64±0.95 b 0.69±0.03 c * 14 7.29±0.38 a 6.66±0.35 a 7.18±0.95 a 0.69±0.03 c * 17 7.68±0.39 a 7.08±0.36 a 7.48±0.93 a 0.69±0.03 c * 20 7.97±0.43 a 7.46±0.36 a 7.66±0.92 a 0.69±0.03 c * 23 8.09±0.45 a 7.75±0.37 a 7.76±0.91 a 0.69±0.03 c * 26 8.09±0.45 a 7.75±0.37 a 7.76±0.91 a 0.69±0.03 c * 29 8.09±0.45 a 7.75±0.37 a 7.76±0.91 a 0.69±0.03 c * *p< 0.05 a-c The same letters in the same row indicate no significant different at α = 0.05 by Tukey's test Table 6. The value of lesion area, F, and Q Lesion area(mm 2 ) F(%) Q(mm 2.%) Before After Before After Before After BG 0.03±0.02 5.97±1.14-10.39±5.75-21.52±5.04 a -0.82±1.08-436.40±72.05 a LB 0.04±0.02 5.15±1.21-10.14±8.75-20.28±5.49 a -1.17±1.20-379.43±66.30 a OF 0.03±0.02 5.78±0.70-9.94±4.61-20.64±4.17 a -0.79±0.52-421.80±47.60 a TB 0.04±0.02 6.12±1.18-8.00±3.79-27.82±3.46 b -0.75±0.49-540.90±69.71 b a-b The same letters in the same column indicate no significant different at α = 0.05 by Tukey's test 과 lesion area 값은그룹간의통계적유의차가없었으나 (p>0.05), F 값, Q 값에서불소를함유한레진군이불소를함유하지않은레진군보다통계적으로유의하게낮았다 (p<0.05)(table 6). 초기값과비교한 lesion area, F 값, Q 값의변화량역시 lesion area 값에서는각군간의통계적차이가없었으나 (p>0.05), F 값, Q 값의변화량에있어서불소를포함한레진이불소를포함하지않은레진보다통계적으로유의하게작은변화량을보임으로써 (p<0.05) 탈회저항성이있음을보여주었다 (Table 7). Table 7. The value of difference between before and after Difference of lesion area(mm 2 ) Difference of F(%) Difference of Q(mm 2 %) BG 5.94±1.14-11.14±7.51 ab -435.58±71.86 a LB 5.11±1.21-10.14±12.20 a -378.26±66.93 a OF 5.74±0.69-10.7±6.03 ab -421.01±47.42 a TB 6.07±1.17-19.82±4.10 b -540.15±69.52 b a-b The same letters in the same column indicate no significant different at α = 0.05 by Tukey's test Table 8. Correlation between fluoride releasing and Lesion area F Q Fluoride releasing -0.177-0.211-0.163 3. 불소유리량과탈회와의상관관계불소유리량과 Lesion area, Q, F 와의상관관계를분석한결과, 불소유리량과각값은미약한음의상관관계를보였다 (Table 8). 고 찰 불소가치아에도포될경우, 치아의주요구성성분인수산화인회석 (hydroxyapatite) 에작용하여수산화이온이불소로치환되고그결과불화인회석 (fluoroapatite) 이형성된다. 이는수산화인회석에비해원자배열이더욱치밀하여법랑질의산에대한용해도를감소시키며 20), 미세경도를증가시키고탈회된법랑질에도포할경우표층하부의재석회화를촉진하여우식활동의정지또는병소의감소를일으킴으로써항우식효과를나타낸다. 이로인해현재
450 The Effect of Orthodontic Resin Cements Containing Fluoride on Fluoride-releasing and... 까지다양한치과수복재료에불소가포함되어져왔다 21-24). 정등 25) 은시판중인불소포함레진을사용하여실험을한결과불소가포함되지않은레진에비해우수한재석회화효과가있었음을보고한바있다. 복합레진에다양한방법으로불소를첨가하여이온교환및가수분해기전에의해지속적으로불소가유리됨으로써이차우식의억제를도모하려는노력들이있었음에도불소첨가로인한물성의저하와기대이하의미미한불소유리량으로인해임상적으로각광받지못하였다 26). 그러나실제로치질에대한불소의재석회화효과는높은불소농도보다는낮은농도라도지속적으로불소가유리될때훨씬우수한것으로보고된바있다 27). Hicks 등 28) 에의하면어느정도의불소농도에서부터우식예방혹은재석회화의촉진이일어나는지정확히알기어려우나, 불소의농도보다는얼마나자주불소를적용하는지가중요하다고하였다. 이런관점에서볼때, 본실험에서사용한불소함유레진의불소유리양은하루에 0.5~1.5 ppm 으로낮은농도이기는하나일정기간불소가유리되므로법랑질탈회의예방, 그리고탈회된법랑질의재석회화에효과가있으리라생각된다. 이는 Underwood 등 29) 의실험결과와유사한데, 불소유리량이 0.5~1.5 mg/gm/day 밖에되지않는미량이었음에도재석회화효과를나타낸결과는불소가유리되는양이나농도보다는그지속성이우식예방에더큰영향을미친다고하였다. 이는 Hicks 등 28) 의보고와도일치한다. 불소방출량과그양상을실험한연구에의하면실험첫째날하루동안가장많은양의불소를유리한다고보고하였는데 30-32), 이를 burst effect 라고하였다 33). 본실험역시모든종류의레진이실험첫째날하루동안많은양의불소가유리되었고이후급격한감소를나타내선행연구들과같은 burst effect 를관찰할수있었다. 실험재료를보관하는용액에따라서도불소유리양상이상이하게나타날수있다고알려져있는데, 주로증류수와인공타액이가장보편적으로사용되어왔다. 문헌에따라약간의논란이있으나, 두용액에서모두시간경과에따른전반적인불소유리양상은유사하지만증류수에서더많은유리량을나타낸다고보고되었다 34). 본실험에서는구강내환경을재현하기위하여인공타액으로실험하였으므로, 증류수로실험한결과와는불소유리량에서차이가나타날수있을것으로사료된다. 불소농도를측정하는여러가지방법중 35) 불소이온전극을사용하는것이최근널리사용되고있다 36,37). 비록불소이온전극이 Hydroxide 이온이외에는직접적인간섭이없기는하지만, 농도자체에반응하는것이아니라활성도에대해반응하기때문에전체적인이온의세기를맞추고용액내에존재하는것보다많은양의이온을더해줌으로써 Hydroxide 이온의간섭을피할수있는범위로용액을완충시켜주며, Fe 3+ 나 Al 3+ 와결합되어있을수 도있는불소를유리시키기위해 TISAB 를첨가한다 38). 본연구에서는불소를포함한레진과불소를포함하지않은레진을각각 10 개씩실험군과대조군으로하여탈회용액에침전후 QLF 를이용하여초기탈회정도를측정하였다. 임상적으로법랑질탈회는브라켓주변에백색병소로나타나고, 확실한경계를띤초기우식이된다 39). 이를규명할수있는방법은여러가지가있는데, 보통은인공병소를이용하고, 편광현미경, 횡단미세방사선촬영 (TMR), 입체현미경그리고전자현미경으로분석한다 40). 그러나이러한방법들은체외에서진행되어임상적용이어렵고 41), 정량화하기어려운 42) 한계를지닌다. 특히 TMR 은민감도와특이도가뛰어나 gold standard 로알려져있으나 43) 시간과노력이필요하고시편을파괴하는단점이있어장기적으로감시하기에는부적합하다 44). 따라서생체내에서법랑질탈회를감지하고수량화하며장기적으로감시할수있는방법이요구되는데, QLF 는그런방법을제공할수있다. QLF 는인간의법랑질초기탈회를평가할수있는광학적이고가시적인빛을기본으로한감지및정량화시스템이다. 이방법의기술적기초는인간의법랑질은자가형광을띠게되는데, 탈회된법랑질은이러한형광량이줄어들게된다는것이다. 형광량강도의차이가탈회정도를정량화할수있게하고, 병소의활동성을평가하기위해장기적으로모니터링을할수있게한다 40). 송등 44) 은초기침식관찰에주로이용하는미세경도와 Q 가강한양의상관관계를보였다고보고하면서 QLF 가적은양의초기침식을관찰하는데유용하다고주장하였다. 또한 Aljehani 등 45) 은치아탈회를평가하는방법중 gold standard 로알려진 TMR 이 QLF 와높은상관계수를나타냈다고함에따라탈회정도를측정하는데에 QLF 가적절하다고생각된다. 이에교정용브라켓을부착하여브라켓주위의탈회정도를측정하는본실험에서는비침습적으로탈회에대한정량적인평가를하기위해 QLF 를이용하였다. 본연구에서는불소를포함한교정용레진과불소를포함하지않은교정용레진모두에서탈회가진행되었다. 그러나불소를포함한교정용레진이불소를포함하지않은레진에비해높은탈회저항성을나타냈는데 (Table 6, 7), 이는선행연구와유사한결과이다. 권등 46) 은불소가유리되는수복물에서우수한탈회저항성이보였다고보고하였다. Basdra 등 7) 또한불소를유리한접착제에서접착제의가장자리와탈회된부위의경계사이의거리가유의하게멀었다고하면서불소를유리한접착제가치아의탈회를억제한다고보고하였다. 양등 47) 은편광현미경을이용하여인공우식병소의깊이를측정하였는데, 그결과불소가함유된전색제에서법랑질탈회에예방효과가있다고보고하였다. 불소유리량에있어서 BG 군이다른군들에비하여다
Journal of Dental Hygiene Science Vol. 11, No. 5, pp. 445~453 (2011) 451 소높은불소유리량을보였으나, 탈회저항성에있어서는다소낮은저항성을보였다. 이는 BG 군이 LB 군과 OF 군에비해 2 일째까지낮은불소유리량을보였고, 탈회저항성측정은탈회용액에침전한 48 시간후에시행하였기때문으로사료된다. 불소유리량과탈회저항성의상관관계에대해 Donly 48), Glasspoole 등 49), Dubroc 등 50) 은불소유리량이높을수록탈회저항성이크다고하였다. Donly 48) 는불소를유리하는복합레진이법랑질경계부에서치아우식을억제한다고하였고 Glasspoole 등 49) 역시불소를포함하고있는모든재료에서통계적으로유의하게법랑질의탈회를막는다고하였다. 쥐를가지고실험한 Dubroc 등 50) 도불소를유리하는레진이탈회와치아우식을감소시킨다고하였다. 비록본실험에서그상관관계가유의하지않았지만, 불소유리량과 lesion area, F, Q 의관계가음의상관관계를나타내어, 불소유리량이증가할수록탈회저항성이높게나타났다 (Table 8). 탈회실험을하기전, 시편은 24 시간동안증류수에보관하였는데, 이는불소유리를억제하는방해요인을제거하고재광화를억제함으로써탈회정도를정확하게측정할수있도록하기위함이다 51). Bell 등 52) 은증류수와인공타액내에서불소유리량을측정하였는데, 인공타액이증류수에비해불소가더적게유리되었고, 10 분간인공타액내에침전한경우시편의 13% 가, 1 시간동안침전한경우에는시편의 17% 가감소되어시간에따라서도감소량이다르게나타났다. 이는인공타액이나재광화용액에침적시킬경우, 용액내무기질이풍부하여재광화에도움을주고, 수복물과무기질농도차이가줄어들기때문이라고하였다. QLF 측정시시편을건조시키는것은탈회정도를측정하는데보다도움을준다. Heinrich-Weltzien 등 53) 은표면의건조와청결이최적의 QLF 를촬영하는데에필수적이라고하였고, 병소를감지하고정량화하기위해표면건조가효과적이라고하였다. 또한병소감지의실패를피하기위해서는각표면마다 5 초이상의표면건조가필요하다고하였다. 이에본실험에서는 QLF 를촬영하기전, 압축공기를이용하여 5 초동안각시편을건조시킨후촬영하였다. 이상을종합해볼때불소를유리하는교정용레진은법랑질의탈회를방지하는효과가있다. 특히불소의국소적인적용이나불소세치제와함께병용할경우더좋은효과를나타낸다. Donly 48) 는불소를유리하는글래스아이오노머와복합레진과함께불소양치또는불소세치제를함께사용하면상승작용을가지며, 법랑질의초기우식에재광화효과를나타낸다고하였는데, 이는재료가불소를전달하는시스템으로써작용하기때문이라고하였다. 본연구는구강내를재현한실험으로실제구강내모든환경에서일어날수있는상황에따른변수를제어할 수없다. 또한실험에사용된치아가과거불소를도포한치아인지를확인할수없는제한점을가지고있다. 따라서향후이를보완할수있는연구가필요하며보다탈회에대한효과적인교정용재료의개발과연구가진행되어야한다고사료된다. 요 약 본연구에서는 4종류의교정용레진시멘트의불소유리량을측정해보고탈회정도를비교해본결과다음과같은결과을얻었다. 1. 불소유리량은불소를포함한실험군이불소를포함하지않은대조군에비해통계적으로유의하게높은불소유리량을보였다 (p<0.05). 2. 누적불소유리량은불소를포함한실험군이불소를포함하지않은대조군에비해통계적으로유의하게높은불소유리량을보였다 (p<0.05). 3. 불소의유리양상은모든시편에서실험첫째날하루동안가장많은양의불소를유리하였다 (p<0.05). 4. 탈회후의 F값과 Q값의절대값은군간에통계적으로유의하지않았으나, 대조군에비해작았다 (p< 0.05). 5. 탈회실험전 후의 F값과 Q값의변화량의절대값은실험군이대조군에비해작았다 (p<0.05). 이상의결과을통해불소를포함한교정용레진시멘트는일정기간불소를유리하고, 법랑질탈회를예방함으로써교정치료시발생할수있는초기우식발생을예방할수있다고사료된다. 참고문헌 1. Gorelick L, Geiger AM, Gwinnett AJ: Incidence of white spot formation after bonding and banding. Am J Orthod Dentofacial Orthop 81(2): 93-98, 1982. 2. Øgaard B, Rølla G, Arends J: Orthodontic appliances and enamel demineralization. Part 1. Lesion development. Am J Orthod Dentofacail Orthop 94(1): 68-73, 1988. 3. Staley RN et al.: Effect of brushing on fluoride release from 3bracket adhesives. Am J Orthod Dentofacial Orthop 126(3): 331-336, 2004. 4. Bishara SE, Chan DCN, Abadir EA: The effects on the bonding strength of fluoride application after etching. Am J Orthod Dentofacial Orthop 95(3): 259-260, 1989. 5. Valk JW, Davidson CL: The relevance of controlled fluoride release with bonded orthodontic appliances. J Dent 15(6): 257-260, 1987. 6. Sadowsky PL, Retief DH, Bradley EL Jr: Enamel fluoride uptake from orthodontic cement and its effect on demineralization. Am J Orthod 79(5): 523-534, 1981. 7. Basdra DK, Huber H, Komposch G: Fluoride released from orthodontic bonding agents alters the enamel surface and inhibits enamel demineralization in vitro. Am J Orthod Dentofacial Orthop 109(5): 466-472, 1996.
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