Pediatric Dentistry. Silvia José Chedid* Jaime Aparecido Cury**

Transcription

1 Brz Orl Res 2004;18(1):18-22 Peditric Dentistry Effect of 0.02% NF solution on enmel deminerliztion nd fluoride uptke y deciduous teeth in vitro Efeito d solução de NF 0,02% n desminerlizção e incorporção de fluoreto pelo esmlte de dentes decíduos in vitro Silvi José Chedid* Jime Aprecido Cury** ABSTRACT: The ppliction of 0.02% NF solution on teeth with cotton sw insted of rushing with fluoride dentifrice hs een suggested for young children to reduce the risk of dentl fluorosis, ut its nticriogenic effect hs not een evluted. Thus, we studied the in vitro effect of 0.02% NF solution on enmel deminerliztion nd fluoride uptke in deciduous teeth; non-fluoride dentifrice nd fluoride dentifrice (1,100 µg F/g) were used, respectively, s negtive nd positive controls. The tretment with fluoride dentifrice ws more effective in reducing enmel deminerliztion (p < 0.05) nd on fluoride uptke y the enmel (p < 0.05) thn the non-fluoride dentifrice nd the 0.02% NF solution. Dt suggest tht the lterntive use of 0.02% NF solution insted of fluoride dentifrice should e reevluted especilly if dentl cries re to e controlled. DESCRIPTORS: Fluorides; Dentifrices; Dentl enmel; Tooth, deciduous; Fluorosis, dentl. RESUMO: A plicção d solução de NF 0,02%, no lugr de dentifrício fluoretdo, tem sido sugerid pr ser plicd com cotonete nos dentes de eês pr reduzir o risco de fluorose dentl. Como o efeito nticriogênico dess recomendção não tem sido estuddo, vliou-se in vitro seu efeito n redução d desminerlizção e incorporção de fluoreto no esmlte de dentes decíduos; dentifrício não fluoretdo e fluoretdo (1.100 µg F/g) form utilizdos como controles negtivo e positivo, respectivmente. O dentifrício fluoretdo foi mis efetivo que solução de NF 0,02% n redução de desminerlizção e n incorporção de fluoreto no esmlte (p < 0,05). Os ddos sugerem que uso lterntivo de NF 0,02% o invés de dentifrício fluoretdo pr reduzir o risco de fluorose dentl deve ser revlido, especilmente se cárie dentl precis ser controld. DESCRITORES: Fluoretos; Dentifrícios; Esmlte dentário; Dente decíduo; Fluorose dentári. INTRODUCTION Fluoride dentifrice is considered n importnt fctor in explining the decline in dentl cries oserved either in developed or in developing countries t the end of the lst century 3,14. However, fluoride dentifrice is lso risk fctor with respect to dentl fluorosis 13 ecuse young children ingest lrge mount of toothpste during rushing 16. In ddition, there is evidence tht dentl fluorosis is incresing in developed countries irrespective of whether the res concerned hve wter fluoridtion or not 12. These findings in developed countries re n lert to developing countries tht hve cries control progrms sed on fluoride use 17. In order to reduce the risk of dentl fluorosis some recommendtions hve een mde for young children: (i) do not use dentifrice, or use non-fluoride dentifrice 7 ; however, the presence of fluoride during toothrushing is considered indispensle 21 ; (ii) use dentifrice with low fluoride concentrtion 9 ; however, the nticries effect of dentifrice with less thn 1,100 µg F/g is not well-estlished 15,19 ; (iii) use smll mount of dentifrice 18 ; however, the nticries effect of this procedure hs not yet een estlished. In ddition to these interntionl recommendtions, the use of 0.02% NF solution for children under 3 yers of ge in Brzil hs een suggested, insted of fluoride dentifrice 23. Prents or gurdins should pply this solution to the children s teeth dily, using cotton sw. This lterntive is sfer thn the use of fluoride dentifrice with regrd to dentl fluorosis ecuse the child is sujected dily to low mount of fluoride (pproximtely 0.01 mg F/cotton sw). However, its nti-cries potentil is unknown. Thus, the im of this study ws to evlute * Associte Professor, Peditric Dentistry, São Leopoldo Mndic Centre of Reserch in Dentistry. ** Professor, Biochemistry, School of Dentistry of Pircic, Stte University of Cmpins. 18

2 Chedid SJ, Cury JA. Effect of 0.02% NF solution on enmel deminerliztion nd fluoride uptke y deciduous teeth in vitro. Brz Orl Res 2004;18(1): the in vitro effect of 0.02% NF solution on enmel deminerliztion nd fluoride uptke in deciduous teeth. MATERIAL AND METHODS Experimentl design Seventy-five enmel locks (3 x 3 mm) were prepred from humn upper incisor deciduous teeth provided y the Humn Tooth Bnk, School of Dentistry, University of São Pulo (USP). The enmel surfce of the locks ws then sequentilly polished nd those with hrdness of 43 ± 3 KHN (knoop hrdness numer) units were rndomized into three groups of 15 specimens ech. The groups of locks, presenting known seline enmel surfce microhrdness, were sumitted to ph-cycling model simulting high criogenic chllenge. During ph-cycling, one group ws treted with non-fluoride dentifrice (negtive control); the experimentl group ws treted with 0.02% NF solution nd the positive control with fluoride dentifrice (1,100 µg F/g, w/w). After ph-cycling, surfce enmel microhrdness ws gin determined in the locks to evlute its loss. Enmel cross-sectionl microhrdness ws lso determined to evlute the cries lesion. In ddition, fluoride in enmel ws ssessed to evlute fluoride uptke in ech tretment. The use of humn teeth ws ethiclly conducted ccording to the Brzilin guidelines (Resolution No. 196 of the Ntionl Helth Council, Helth Ministry, Brsíli, DF, 10/03/1996). ph-cycling The enmel locks were sumitted to phcycling model for 10 dys, simulting high cries chllenge, essentilly ccording to Fetherstone et l. 5. The locks were kept in deminerlizing solution (2.0 mm clcium, 2.0 mm phosphte in M cette uffer, ph 4.3) t 37 o C for 3 h (60 ml per lock), nd in reminerlizing solution (1.5 mm clcium, 0.9 mm phosphte, 150 mm of KCl in 0.1 M Tris uffer, ph 7.0) for 21 h (30 ml per lock). During the weekend, the enmel locks were stored in the reminerlizing solution nd oth solutions were chnged efore strting nother cycle of 5 dys. During ph-cycling, twice dy, the enmel locks were treted with the dentifrices or the 0.02% NF solution. Fluoride tretment The tretments were pplied to the enmel locks efore nd fter the time tht these were immersed in the deminerlizing solution. The negtive control group ws treted with non-fluoride dentifrice (plceo) nd the positive one with fluoride dentifrice (Tndy, Colgte-Plmolive Ind. Com. Ltd., São Bernrdo do Cmpo, SP, Brzil) contining 1,100 µg F/g (w/w s NF). Both dentifrices were silic-sed. The dentifrices were pplied to the enmel surfce for 20 s, using toothrush, ut without pressure. The mount of dentifrice pplied ws 0.1 ± 0.02 g nd it ws stndrdized y collecting the dentifrice set in the tip-top cp of the dentifrice tue. In the experimentl group of enmel locks, 0.02% NF solution (w/v) ws pplied to the enmel surfce with cotton sw for 20 s. After the tretments the locks were immersed in rtificil sliv 2 (1.5 mm C, 3.0 mm P, 20.0 mm NHCO 3, ph 7.0, 1.0 ml per lock). The locks were riefly wshed with deionized wter nd the rtificil sliv ws chnged for fresh mount every time tretment ws pplied. After the ph-cycling, the enmel of the locks ws evluted. Microhrdness determintion After ph-cycling, the surfce microhrdness of the enmel lock ws mesured gin. Five indenttions spced 100 µm from ech other nd from the seline ones were mde. A Shimdzu HMV-2000 (Shimdzu Corp., Kyoto, Jpn) microhrdness tester with Knoop dimond with 50 g lod ws used for 5 s. The percentge of surfce microhrdness chnge (%SMC) ws clculted (%SMHC = hrdness fter ph-cycling seline 100/seline). Surfce microhrdness (SMH) ws evluted ecuse this method is highly sensitive nd reproducile to evlute enmel deminerliztion 24. After surfce microhrdness nlysis, the locks were longitudinlly sectioned in the centre. Hlf of ech lock ws used for crosssectionl microhrdness determintion nd the other hlf for fluoride enmel nlysis. To perform cross-sectionl microhrdness (CSMH) tests, one of the hlves of ech lock ws emedded in crylic resin so tht the cut section ws exposed nd could e polished. The indenttions were mde t 20 µm from the outer enmel surfce up to 100 µm. Three lnes of indenttions were mde, one in the centrl region of the dentl lock nd the other two 100 µm elow nd ove it, using Knoop dimond with 25 g lod for 5 s. The men vlues t ll mesuring points, t ech distnce from the surfce were then verged. CSMH ws used to evlute deminerliztion con- 19

3 Chedid SJ, Cury JA. Effect of 0.02% NF solution on enmel deminerliztion nd fluoride uptke y deciduous teeth in vitro. Brz Orl Res 2004;18(1): sidering tht there is high correltion (r = 0.91) etween enmel microhrdness nd percentge of minerl in cries lesions, nd the vlues of Knoop hrdness numer (KHN) were converted to minerl contents (%vol) using the reltion: minerl content = 4.3 ( KHN ) , ccording to Fetherstone et l. 6. Fluoride concentrtion in enmel Five enmel lyers were sequentilly removed from hlf of ech lock y immersion in 0.25 ml of 0.5 M HCl for 30, 30, 30, 60 nd 60 s under gittion 10. An equl volume of TISAB II ph 5.0 modified with 20 g NOH/l ws dded to ech solution contining the dissolved enmel lyer. Fluoride mesurements were performed using n ion-selective electrode Orion nd n ion nlyzer Orion EA-940 (Orion Reserch Inc., Boston, MA, USA), previously clirted with vrious stndrd fluoride solutions from 0.1 to 5.0 µg F/ml. The thickness of enmel lyer removed during the cid iopsy ws clculted from the inorgnic phosphorus concentrtion, determined colorimetriclly 8. Phosphorus content in enmel of 17.4% ws estimted to clculte the mount of enmel removed nd enmel density of 2.92 ws considered to clculte the depth of ech enmel lyer 11. Sttisticl nlysis The SMH nd fluoride uptke dt were nlyzed y ANOVA, fter trnsformtion y exponentil nd squre root respectively. The difference mong the tretments ws nlyzed y Newmn- Keuls test. The results of cross-sectionl microhrdness were nlyzed y the non-prmetric Kruskl-Wllis test. The softwre BioEstt 2.0 ws used 1 for ll the nlyses, nd the significnce level ws estlished t 5%. RESULTS None of the tretments were le to prevent the reduction of surfce microhrdness (Tle 1), ecuse the difference (seline vlues vs. fter tretment) ws sttisticlly significnt (p < ). However, the effect of the tretments ws found (p < ) y ANOVA regrding the percentge of SMH chnge (%SMC). The tretment with fluoride dentifrice ws more effective thn those with plceo dentifrice nd with 0.02% NF regrding reduction of the percentge of SMC (p < 0.01). The effect of 0.02% NF tretment ws not sttisticlly significnt in comprison with plceo dentifrice (p > 0.05). Grph 1 shows tht only the tretment with fluoride dentifrice (FD) ws sttisticlly more effective thn the plceo (PD) in reducing the loss of minerl t ll the distnces from the enmel surfce (p < 0.05). The results oserved with the 0.02% NF solution were not sttisticlly different to those oserved with the non-fluoride dentifrice tretment (PD) regrding cries lesions. With regrd to fluoride uptke (Grph 2), dt collected from the first lyer of enmel nlyzed show tht the 0.02% NF solution ws le to increse concentrtions of F in enmel in comprison with the non-fluoride dentifrice (PD). However, the fluoride dentifrice (FD) ws more effective thn the other two tretments (p < 0.05). DISCUSSION AND CONCLUSION Some recommendtions hve een mde to reduce the risks of dentl fluorosis, considering tht pre-school children involuntrily swllow considerle mount of dentifrice during toothrushing. However, the effect of these recommendtions on the nticriogenic properties of fluoride hs not een evluted. In the present study we evluted the in vitro use of 0.02% NF solution, in terms of its effect on the nticriogenic potentil of fluoride. In this in vitro study we tried to simulte clinicl situtions regrding toothrushing y children nd cries: (i) s sustrte we used deciduous TABLE 1 - Surfce microhrdness nlysis of enmel locks ccording to the tretments (mens ± SD; n = 15). Tretments Bseline SMH After tretment %SMC Plceo dentifrice ± 17.7 A 64.8 ± 59.7 B 82.0 ± % NF ± 13.2 A 63.2 ± 27.8 B 82.4 ± 7.4 Fluoride dentifrice ± 18.1 A ± 50.2 B 54.1 ± 13.2 Mens followed y different letters re sttisticlly significnt (p < 0.05). Cpitl letters show difference etween seline nd fter tretment, SMH for ech tretment nd lower cse mong the tretments. SMH = surfce microhrdness; SMC = surfce microhrdness chnge. SD = stndrd devition. 20

4 Chedid SJ, Cury JA. Effect of 0.02% NF solution on enmel deminerliztion nd fluoride uptke y deciduous teeth in vitro. Brz Orl Res 2004;18(1): %vol minerl c GRAPH 1 - Enmel volume minerl percentge ccording to the tretments nd the distnce (µm) from the surfce. Different letters show significnt difference (p < 0.05) mong tretments t ech distnce from the enmel surfce; rs denote stndrd errors (n = 15). PD: non-fluoride dentifrice; FD: fluoride dentifrice., Depth ( m) PD FD 0.02% NF Fluoride concentrtion in enmel (mgf/kg) 3,000 2,500 2,000 1,500 1,000 c Depth ( m) PD FD 0.02% NF GRAPH 2 - Fluoride concentrtion in enmel (mg/kg) ccording to the groups/tretments nd the distnce (µm) from the surfce. Different letters show significnt difference (p < 0.05) mong groups/tretments t ech distnce from the enmel surfce; rs denote stndrd errors (n = 15). PD: non-fluoride dentifrice; FD: fluoride dentifrice. teeth, (ii) wy to use smll mount of dentifrice ws idelized, (iii) ph-cycling model ws used to mimic cries lesion development. The results clerly showed tht the use of smll mount of fluoride dentifrice ws s effective in reducing enmel deminerliztion (Tle 1 nd Grph 1) s in forming fluoride in enmel (Grph 2). However, the findings with the use of 0.02% NF solution were not conclusive ecuse it did not show etter effects thn the negtive control used (non-fluoride dentifrice) for ll the evlutions mde. The positive effect of fluoride dentifrice nd the lck of effect of 0.02% NF solution re comprehensile ecuse the concentrtion of fluoride in dentifrice (1,100 µg F/g) is 12 times higher thn tht in the 0.02% NF solution (90 µg F/ml). It is recognized tht loosely-ound fluoride, like CF 2, is the product formed in the enmel, which is responsile for the nticriogenic effect of topicl fluoride 22. Considering tht the formtion of CF 2 -like product is dependent on the concentrtion of fluoride pplied to the enmel 20, the result found is not surprising. However, some effects of the 0.02% NF solution were expected, ecuse 90 µg F/ml of fluoride is recting on the enmel surfce twice dy. We did not find ny effect of this fluoride solution in reducing enmel surfce deminerliztion (Tle 1), nd very smll effect ws oserved in the reduction of minerl loss in the cries lesion (Grph 1) nd in fluoride uptke (Grph 2). These findings suggest tht 0.02% NF solution pplied with cotton sw in enmel hs doutful nticriogenic potentil. Thus, this lterntive to fluoride dentifrice cn e sfer with regrd to dentl fluorosis risk, ut it must not e chosen, especilly for child with cries risk or ctivity. The use of smll mount of dentifrice would e etter solution considering the enefits nd risks of fluoride use 17. With regrd to the effect of fluoride dentifrice, during toothrushing we did not simulte the dilution of the dentifrice y sliv, which is pproximtely 3-4 times. We tried to simulte the dilution fter toothrushing, y immersing the enmel locks in rtificil sliv for 30 min. The dilution of the dentifrice y sliv is importnt, s shown y DenBesten, Ko 4 (1996).The uthors suggest tht the reduction in the mount of fluoride toothpste to pe-sized mount should e limited only to young children, who re t risk of ingesting toothpste. However, these uthors did the study with 4-5 yer old children nd the risk of dentl fluorosis occurs t n erlier ge. In conclusion, the results of this lortory study suggest tht the use of 0.02% NF solution in clinicl sis hs very little nticriogenic potentil, nd the recommendtion to use it insted of fluoride dentifrice should e reevluted. ACKNOWLEDGEMENTS The uthors thnk Professor Rosn C. Prente, University of Amzons, for ssistnce in sttisticl nlysis; Miss Mriz de Jesus Crlos Sores 21

5 Chedid SJ, Cury JA. Effect of 0.02% NF solution on enmel deminerliztion nd fluoride uptke y deciduous teeth in vitro. Brz Orl Res 2004;18(1): nd Mr. Wldomiro Vieir Filho, School of Dentistry of Pircic, Stte University of Cmpins, for technicl ssistnce; Miss Adrin Frnco Pes Leme, Doctorte Student in Criology, School of Dentistry of Pircic, Stte University of Cmpins, for helping with the grphs. REFERENCES 1. Ayres M, Ayres Jr M, Ayres DL, Sntos AS. BioEstt 2.0: sttisticl pplictions in iologicl sciences nd medicine. Belém, Sociedde Civil Mmiruá, Brsíli, CNPq; Birkelnd JM. The effect of ph on the interction of fluoride nd slivry ions. Cries Res 1973;7: Clrkson JJ. Interntionl collortive reserch on fluoride. J Dent Res 2000;79: DenBesten P, Ko HS. Fluoride levels in whole sliv of preschool children fter rushing with 0.25 g (pe-sized) s compred to 1.0 g (full-rush) of fluoride dentifrice. Peditr Dent 1996;18: Fetherstone JDB, O Reilly MM, Shriti M, Brugler S. Enhncement of reminerliztion in vitro nd in vivo. In: Lech SA (editor). Fctors relting to deminerliztion nd reminerliztion of the teeth. Oxford: IRL Press; p Fetherstone JDB, ten Cte JM, Shriti M, Arends J. Comprison of rtificil cries-like lesions y quntittive micrordiogrphy nd microhrdness profiles. Cries Res 1983;17: Feigl RJ. Recent modifictions in the use of fluorides for children. Northwest Dent 1983;62: Fiske CH, Surrow Y. The colorimetric determintion of phosphorous. J Biol Chem 1925;66: Horowitz HS. The need for toothpstes with lower thn conventionl fluoride concentrtions for preschool-ged children. J Pulic Helth Dent 1992;52: Koo H, Cury JA. Solule clcium/smfp dentifrice: effect on enmel fluoride uptke nd reminerliztion. Am J Dent 1998;11: Lzzri EP. Dentl iochemistry. 2 nd ed. London: Le & Feiger; Levy SM, Kohout FJ, Kiritsy MC, Heilmn JR, Wefel JS. Infnts fluoride ingestion from wter, supplements nd dentifrice. J Am Dent Assoc 1995;126: Mscrenhs AK. Risk fctors for dentl fluorosis: review of the recent literture. Peditr Dent 2000;22: Nrvi PC, Frzão P, Cstellnos RA. Decline in cries experience in permnent teeth of Brzilin scholrs t the end of the twentieth century. Odontol Soc 1999;1: Newrun E. Current regultions nd recommendtions concerning wter fluoridtion, fluoride supplements nd topicl fluoride gents. J Dent Res 1992;71: Piv SM, Cury JA. Fluoride dentifrice nd risk of dentl fluorosis. RPG Rev Pós Grd 2001;8: Piv SM, Lim YBO, Cury JA. Fluoride intke y Brzilin children from two communities with fluoridted wter. Community Dent Orl Epidemiol 2003;31: Png DT, Vnn WF Jr. The use of fluoride-contining toothpstes in young children: the scientific evidence for recommending smll quntity. Peditr Dent 1992;14: Richrds A, Bnting DW. Fluoride toothpstes. In: Fejerskov O, Ekstrnd J, Burt BA. Fluoride in dentistry. 2 nd ed. Copenhgen: Munksgrd; p Sxegrd E, Röll G. Fluoride cquisition on nd in humn enmel during topicl ppliction in vitro. Scnd J Dent Res 1988;96: Scheie AA. Dentifrices in the control of dentl cries. In: Emery G, Roll G (editors). Clinicl nd iologicl spects of dentifrices. New York: Oxford University Press; ten Cte JM. Review on fluoride, with specil emphsis on clcium fluoride mechnisms in cries prevention. Eur J Orl Sci 1997;105: Wlter LRF. Dentistry for toddler. São Pulo: Artes Médics; Zero DT. In situ cries models. Adv Dent Res 1995;9: Received for puliction on My 05, 2003 Sent for ltertions on Jn 27, 2004 Accepted for puliction on Fe 06,