Originl Article Nickel nd Chromium Levels in the Sliv nd Serum of Ptients With Fixed Orthodontic Applinces Günseli Ağoğlu, DDS, PhD ;Tülin Arun, DDS, PhD b ; Belgin İzgü, MD c ;Ayşen Yrt, MD d Abstrct: The im of this study ws to evlute the concentrtions of nickel nd chromium ions in slivry nd serum smples from ptients treted with fixed orthodontic pplinces. A second im of this study ws to determine ny significnt chnges in these concentrtions during ny period of the tretment time. Sliv nd blood smples were collected from 100 ptients rnging in ge from 12 to 33 yers. Twenty smples from ech group were obtined. The groups were s follows: In the first group, sliv nd blood smples were collected before insertion of the fixed pplinces. In the second, third, fourth, nd fifth groups, smples were collected t 1 week, 1 month, 1 yer, nd 2 yers fter pplince insertion. The serum ws prepred by centrifuging the blood smples t 3000 rpm for 10 minutes. The fixed pplinces consisted of n verge of 4 bnds nd 20 bonded brckets. No pltl or lingul pplinces welded to bnds or extrorl uxiliry pplinces were used. The spectrophotometric determintions were crried out using electrotherml tomic bsorption spectrophotometry. The results indicted certin differences in the mounts of nickel nd chromium relesed from fixed orthodontic pplinces during different periods of tretment. The Mnn-Whitney U-test from the SPSS sttistics progrm ws used to nlyze the significnce of the differences between no-pplince smples nd those obtined with the pplinces present. In the serum, there were sttisticlly significnt increses in ion concentrtion in the second-yer groups. In sliv smples, nickel nd chromium reched their highest levels in the first month nd decresed to their initil level in the rest of the groups. It cn be concluded tht fixed orthodontic pplinces relese mesurble mount of nickel nd chromium when plced in the mouth, but this increse doesn t rech toxic levels for nickel nd chromium in the sliv nd serum. (Angle Orthod 2001;71:375 379.) Key Words: Trce elements; Nickel; Chromium; In vivo; Atomic bsorption spectrophotometry INTRODUCTION The stinless steel used for orthodontic brckets, bnds, nd wires contins pproximtely 18% chromium (Cr) nd 8% nickel (Ni). Nickel nd chromium hve dermtologicl, toxicologicl, nd possibly mutgenic effects. Nickel is the most common cuse of metl-induced llergic contct dermtitis. 1 6 Chromium llergy is estimted t 10% in mle subjects nd 3% in femle subjects. 7 Blnco-Dlmu et l 8 Resech Assistnt, Deprtment of Orthodontics, Fculty of Dentistry, Mrmr University, İstnbul, Turkey. b Associte Professor, Deprtment of Orthodontics, Fculty of Dentistry, Yeditepe University, İstnbul, Turkey. c Reserch Assistnt, Deprtment of Bsic Sciences, Fculty of Medicine, Uludğ University, Burs, Turkey. d Professor, Deprtment of Bsic Sciences, Fculty of Dentistry, Mrmr University, İstnbul, Turkey. Corresponding uthor: Tülin Arun, DDS, PhD, Yeditepe Üniversitesi, Dişhekimliği Fkültesi, Bğdt Cd. No. 238, Göztepe, İstnbul, Turkey. (e-mil: trun@mil.koc.net). Accepted: Jnury 2001. Submitted: November 2000. 2001 by The EH Angle Eduction nd Reserch Foundtion, Inc. found 31.9% of the women nd 20.7% of the men in popultion of 403 showed positive rection to ptch test with nickel sulfte. Jones et l 9 reported positive skin ptch test to nickel sulfte in 20% of the femle ptients nd 2% of the mle ptients in popultion of 100 dentl ptients. Therefore, there is the possibility tht nickel nd chromium relesed from stinless steel orthodontic bnds, brckets, nd wires might elicit n llergic rection. Nickel llergy rections to orthodontic pplinces hve been reported fter the use of fcebow nd neck strps 10,11 nd lso fter the insertion of orthodontic rch wires. 12,13 The most significnt humn exposure to nickel nd chromium occurs through the diet. The verge dietry intke for these metls hs been estimted to be 200 300 g/d for nickel 3 nd 50 200 g/d for chromium. 14 The known cncer risk presented by nickel, chromium, nd their compounds hs been documented in the literture. 3,7 In the orl environment, biodegrdtion of metls occurs usully by electrochemicl brekdown. 15 19 The in vitro relese rte from full-mouth orthodontic pplinces ws reported to be 40 g/d for nickel nd 36 g/d for chromium. 20 Kerousuo et l 2 found tht, during the first month of 375
376 AĞAOĞLU, ARUN, İZGÜ, YARAT tretment, fixed orthodontic pplinces did not significntly ffect nickel nd chromium concentrtions of sliv. The relese of nickel from fixed orthodontic pplinces ws reported to be relted to both the composition nd the method of mnufcture of the pplinces but not to be proportionl to the nickel content. 21 Brrett et l 22 concluded tht the relese rtes of nickel or chromium from stinless steel nd nickel-titnium rch wires were not significntly different. The purpose of this study ws to determine if there ws significnt increse in serum nd slivry levels of nickel nd chromium in ptients hving fixed orthodontic tretment nd to evlute the concentrtions of nickel nd chromium ions present following different durtions of orthodontic tretment time. MATERIALS AND METHODS The ptients in this study were treted in the Deprtment of Orthodontics, Fculty of Dentistry, University of Mrmr. Sliv nd blood smples were collected from 100 ptients (67 femles nd 33 mles) rnging from 12 to 33 yers of ge, with n verge ge of 19.5 yers. Slivry nd blood smples were tken from ptients who were treted using fixed orthodontic pplinces. Orthodontic pplinces consisted of n verge of 4 bnds nd 20 bonded brckets mnufctured by Unitek (Monrovi, Cliforni), nickel titnium wires mnufctured by Ormco (Glendor, Cliforni), nd stinless steel wires mnufctured by Unitek. Criteri of ptient inclusion were s follows: Ptients were in the permnent dentition period, Ptients did not hve ny mlgm fillings nd metl restortions, which could ny glvnic corrosion in the mouth, Ptients hd stndrd edgewise brckets on the incisors, cnines, nd premolrs nd stndrd edgewise bnds on the first molrs, Ptients did not hve ny pltl or lingul pplinces welded to the bnds (ie, rpid mxillry expnsion pplince) or extrorl uxiliry orthodontic pplinces (ie, hedger). In order to determine slivry nd serum nickel nd chromium levels during different periods of tretment, 20 smples from ech group were obtined. The groups were s follows: In the first group, sliv nd blood smples were collected before insertion of the fixed pplinces. In the second, third, fourth, nd fifth groups, smples were collected 1 week, 1 month, 1 yer, nd 2 yers fter pplince insertion, respectively. All sliv smples were collected in the morning before brekfst. The ptients rinsed their mouths thoroughly with deionized nd distilled wter before the collection. Sliv ws smpled for 5 minutes with the mouth closed without stimultion nd trnsferred to plstic test tubes. Blood ws TABLE 1. Slivry Cr nd Ni Levels in Different Periods of Fixed Tretment Time (ppb) Groups Men SD Cr 1 Cr 2 Cr 3 Cr 4 Cr 5 Ni 1 Ni 2 Ni 3 Ni 4 Ni 5 0.76 0.53 1.53 0.91 0.54 4.45 4.12 11.53 7.01 4.44 1.43 0.57 3.31 1.03 0.67 2.87 2.65 9.24 7.15 4.00 Cr 1 nd Ni 1, men collection before insertion of the pplince; C2 nd Ni 2, men collection t end of the first week; C3 nd Ni 3, men collection t end of the first month; C4 nd Ni 4, men collection t end of the first yer; nd C5 nd Ni 5, men collection t end of the second yer. obtined from the ntecubitl foss of the rm nd centrifuged t 3000 rpm for 10 minutes in order to prepre the serum. Acid-wshed plstic continers were used for storge of sliv nd serum smples. The smples were kept t 20 C until they were processed. The spectrophotometric determintions were crried out using n electrotherml tomic bsorption spectrophotometer in Uludğ University Fculty of Medicine (Unicm 90 Grphite Furnce, ATI Unicm 929 AAS). Before the nlysis, smples were centrifuged t 3000 rpm for 10 minutes to settle prticulte mtter. A clibrtion curve ws mde from the results obtined with stndrd solutions prepred with the sme regents s those used for the serum smples. Synthetic sliv ws used for the clibrtion curve mde for the slivry nlysis. Ech test ws nlyzed 3 times nd the verge ws used s the result. Before ech test, 1 distilled wter smple ws processed in order to prevent possible contmintion. The insoluble precipitte ws not included in the nlysis becuse of the problem of prticles cusing vrition in the results. The Mnn-Whitney U-test from the SPSS sttistics progrm ws used for sttisticl nlysis of the results. The sttisticlly significnt differences were nlyzed in 5 different periods of tretment time for the 4 min groups, which included chromium in sliv, nickel in sliv, chromium in serum, nd nickel in serum. RESULTS The results indicte certin differences in the mounts of nickel nd chromium in sliv nd serum of the ptients with fixed orthodontic pplinces during different periods of tretment time. In our study, relese of chromium in sliv ws 0.53 1.53 ppb nd nickel in sliv ws between 4.12 nd 11.53 ppb (Tble 1). Levels of nickel serum were found to be between 7.87 nd 10.27 ppb, while levels of chromium serum were found to be between 6.16 nd 10.98 ppb (Tble 2).
NICKEL AND CHROMIUM RELEASE FROM ORTHODONTIC APPLIANCES 377 TABLE 2. Serum Cr nd Ni Levels in Different Periods of Fixed Tretment Time (ppb) Groups Men SD Cr 1 Cr 2 Cr 3 Cr 4 Cr 5 Ni 1 Ni 2 Ni 3 Ni 4 Ni 5 6.21 6.23 7.02 6.16 10.98 8.36 9.03 8.53 7.87 10.27 21.30 21.62 21.43 20.76 29.28 11.20 10.45 10.81 12.08 14.17 Cr 1 nd Ni 1, men collection before insertion of the pplince; C2 nd Ni 2, men collection t end of the first week; C3 nd Ni 3, men collection t end of the first month; C4 nd Ni 4, men collection t end of the first yer; nd C5 nd Ni 5, men collection t end of the second yer. TABLE 4. Mnn-Whitney U-Test for Serum Cr nd Ni Levels Prmeter (Cr) Test (P) Prmeter (Ni) Test (P).1086.9514.8721.0071**.0414*.1889.0007***.8547.0327*.0138* * P.05, ** P.01, *** P.001..1563.8554.0432*.5634.1961.0018**.3367.0230*.7679.0093** TABLE 3. Mnn-Whitney U-Test for Slivry Cr nd Ni Levels Prmeter (Cr) Test (P ) Prmeter (Ni) Test (P ).7319.0220*.1423.2608.0356*.1416.5625.8085.0115*.0463* * P.05, ** P.01, *** P.001..8190.0531*.5400.5723.0564*.6336.5947.1760.0454*.3954 FIGURE 2. Cr nd Ni levels in sliv during different periods of tretment time. In slivry smples, Ni nd Cr vlues incresed in the first-month group compred with the initil nd the firstweek groups. The decrese in the vlues of the second-yer group ws lso sttisticlly significnt when compred with the first-month group (Tble 3, Figure 1). In serum smples, there ws sttisticlly significnt increse in the mount of chromium in the second-yer group in comprison with the other groups (Tble 4, Figure 2). There ws no reltionship between serum nd slivry nickel levels in different periods of fixed orthodontic tretment. In the first month of fixed orthodontic tretment, slivry nd serum Cr levels were found to be incresed in comprison with the vlues of the first-week group. FIGURE 1. Cr nd Ni levels in serum during different periods of tretment time. DISCUSSION Most of the metls used in the orl cvity cn be expected to undergo some type of corrosion. Severl previous studies hve reported on the corrosive behvior of orthodontic wires, brckets, bnds, or pplinces seprtely. In our study, we didn t seprte the pplince components under in vitro conditions becuse, in orthodontic tretment, wires, brckets, nd bnds re used together in the orl environment. In this investigtion, the im ws to determine the corrosion during different periods of stndrd fixed orthodontic tretment. The min reson for choosing crosssectionl mteril ws to nlyze mny ptients. The criteri would limit the mteril if the ptients were included longitudinlly.
378 AĞAOĞLU, ARUN, İZGÜ, YARAT Previous studies hve not investigted the corrosion cused by fixed orthodontic pplinces in the orl cvity over the long term. Most studies hve lso used rtificil slivry solutions. Sliv hs dynmic composition tht my be ffected by mny physiologic vribles such s diet, slivry ph, helth conditions, nd slivry flow rte. 23 In order to stndrdize the mteril, the sliv ws collected from ptients who did not hve ny helth problems or ny cries in the mouth. All the smples were tken in the morning before brekfst nd the ptients rinsed their mouths thoroughly with deionized nd distilled wter before the collection. In this study, we preferred to use sliv smples obtined from orthodontic ptients in order to nlyze the relese in the dynmic orl cvity environment. Artificil slivry solutions re not commonly used in long-term studies bsed on their precipittion disdvntge. Fixed orthodontic tretment generlly lsts bout 2 yers, so there ws necessity for long-term reserch of the relese from the fixed orthodontic pplinces. The purpose of this study ws to determine if there ws significnt increse in the mounts of nickel nd chromium in the serum nd sliv of ptients hving fixed orthodontic tretment over 5 different periods of tretment time. The spectrophotometric determintions were crried out using electrotherml tomic bsorption spectrophotometry with grphite furnce. This is common method used for trce element nlysis in the literture. 2,15,20 22,24 31 The concentrtions of slivry nickel nd chromium show lrge vritions in the literture. According to the different reports, the men concentrtion of chromium is between 1 nd 61 ppb 2,24,25 nd the men concentrtion of nickel is between 1 nd 55 ppb. 2,24,26 In our study, the relese of chromium in sliv ws between 0.53 nd 1.53 ppb nd the relese of nickel in sliv ws between 4.12 nd 11.53 ppb. These levels re within the norml rnges nd re fr below the verge dily dietry intke of 300 g nickel nd 50 200 g chromium. 3,14 In the literture, the levels of nickel nd chromium in serum were found to be pproximtely 0.2 ppb. 27 30 In our study, the levels of nickel in serum were between 7.87 nd 10.27 ppb nd the levels of chromium in serum were between 6.16 nd 10.98 ppb. The higher vlues found in serum might be the result of contmintion from the stinless steel venipuncture needle. In serum smples, there ws sttisticlly significnt increse of chromium vlues in the second-yer group in comprison with the other groups. No dt re vilble in the literture to compre with our results for long periods of tretment. Our short-term findings for serum vlues re in ccordnce with the study by Bishr et l, 31 who lso did not find ny differences of blood nickel mounts in 4 5 month periods of time. In the slivry smples, Ni nd Cr vlues were incresed in the first-month group in comprison with the initil nd the first-week groups. The decrese in the vlues of the second-yer group ws lso sttisticlly significnt when compred with the first-month group. Our findings for the first-week group re consistent with the findings reported by Kerousuo et l 2 but re in contrst with the first-month results of the sme study. There re no dt vilble with which to compre our results for long periods of tretment, s our dt relted to serum smples. CONCLUSION Our findings indicte tht mesurble mounts of nickel nd chromium cn be found in the serum nd sliv of the ptients wering fixed orthodontic pplinces but tht these vlues might chnge during different periods of orthodontic tretment. 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