, 300 # , 26. 7% g N ac l 0. 4 g KC l g CaC l2 2H 2O g N a2s 2H 2O g N ah 2PO 4. . P indbo rg [4 ],

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1 23 1 V o l 23, N o TR IBOLO GY Jan, , 3, 2, 1, 3 (1., ; 2., ; 3., ) : 3 ph,,, ;,. : ph = 4. 0, ; ph = 4. 0 ; ph = ,,.,. : ; ; ; : TQ : A : (2003) ,,, , 26. 7%., [1, 2 ],. [3 ], 52% 5 6. P indbo rg [4 ], 3.,. 3, [5 ], ,,,, 300 # 500 # 800 # #, A l2o 3, ggl (m alic acid, M ) ( citric acid, C) ( lactic acid, L ), ph g N ac l 0. 4 g KC l g CaC l2 2H 2O g N a2s 2H 2O g N ah 2PO 4 2H 2O 1 g, ml, , 6 ( W ) 10 m in,. Op timo l SRV ;, 24 (, ) ; 2 ; 0. 5 mm, 10 H z, 20 N,, , : ; : g, e2m ail: qiuyinong@w est163. com. :,, 1971,,.

2 1 : 43 ; (SEM ), X t. 7, 7 10 m in, Everone M H 25, 10,.,, 2. 1, JSM 25600LV (EDA X) Ca P Table 1 Averaged wear volume loss of enamel and standard dev iation af ter treated with distilled water and var ious ac id solution s and the one way ANOVA result So lution Samp les tested X { ṡ d. gmm 3 F value P value M M C C P < L L W , M 2. 0 M 4. 0 C2. 0 C4. 0 L 2. 0 L 4. 0 W ph , F [6 ] : F = S A, S A = S A S E, S E= S E k- 1 n- k. (1) : S A ; S E ; k ; n, F = 4. 32, P ,. t, F 2, t : : t= S x - y 1 n x + 1 ny ; (2) : t= - x - y S 2 x + S 2 y n x ny. (3) t 2, P < 0. 05, 2 t ( ) Table 2 Compar ison of the wear volume loss of enamel by t- test So lution L 4. 0 L 2. 0 C4. 0 C2. 0 M 4. 0 M 2. 0 W M M C C L Refers to P < 0. 05, o therw ise P > P < 0. 05, P > ,. : ph = 4. 0, ; ph = 4. 0, ; ph = 2. 0, 3 ; ph, ph

3 44 23 (a) D ecreasing rate of hardness (b) Increasing rate of toughness F ig 1 V ariation of hardness and toughness of enam el treated w ith different so lutions 1. :, M 4. 0 ; 3 ; ph 3 > >, > > (, HA ) [7 ], : Ca10 (PO 4) 6 (OH ) 2 10Ca PO OH - PO H + H PO H + H 2PO H + H 3PO 4,,,. ph [8 ], ph H ughes [2 ] 3, ph ; ; 30 m in 10 Λm, ;., HA, R etziu s, [9, 10 ],, HA Ca 2+ PO 4 3- OH -,,,,. 2 SEM. : [ 2 (a b) ],,,, ph = 4. 0, ph = 2. 0 ;,, [ 2 (c d) ];,,, ph = 2. 0 [ 2 (e f) ];, [ 2 (g) ]. Ca P [9 ], Ca P,. 3 EDA X. : ph = 4. 0, Ca P ph = 2. 0 ; ph = 4. 0 Ca, Ca P.., ph,, Ca P.,.,,,, [11 ].,

4 1 : 45 (a) T reated w ith M 2. 0 (b) T reated w ith M 4. 0 (c) T reated w ith C2. 0 (d) T reated w ith C4. 0 (e) T reated w ith L 2. 0 (f) T reated w ith L 4. 0 (g) T reated (h) M agnified im age of (a), w ith W W refers to w o rn area, N to eroded area F ig 2 SEM mo rpho logies of w o rn surfaces of enam el treated w ith different so lutions 2 SEM [ 2 (h) ],. 3,,,..,, ph = 2. 0 ph = ph, [ 4 (a) ], [ 4 (b) ].,,

5 46 23 F ig 3 V ariation of Ca and P content w ith in and out of the enam el w ear scar treated w ith different so lutions 3 C r P (a) T reated w ith C4. 0 (b) T reated w ith L 4. 0 F ig 4 SEM mo rpho logies show ing w ear debris of the enam el treated w ith C4. 0 and L C4. 0 L 4. 0 SEM, ph = 4. 0 ;,. ph = 2. 0,,,,,. [12 ],. Dogan [13 ],,,.,,,,,. 3 a. 3,. 3. b. ph (2. 0),, ; ph (4. 0),,. : [ 1 ] W est N X, M axw ell A, H ughes J A, et al. A m ethod to m easure clinical ero sion: the effect of o range juice consump tion on ero sion of enam el [J ]. 1998, 26: Journal of D entistry, [ 2 ] H ughes J A,W est N X, Parker D M, et al. Effects of ph and concentration of citric, m alic and lactic acids on enam el, vitro [J ]. Journal of D entistry 2000, 28: [ 3 ] M O B rien. Ch ildren s dental health in the U nited Kingdom in

6 1 : [ R ]. O ffice of Population Censuses and Surveys, L ondon: HM SO, [ 4 ] P indbo rg J J. Patho logy of the dental hard tissues [M ]. Copenhagen: M unskgaard, [ 5 ] L i Hong ( ), Zhou Zhongrong ( ), Zhang J ie ( ), et a l. Comparative study of the friction and w ear behavio r of natural too th and several dental p ro sthetic m aterials ( ) [J ]. T ribo logy ( ), 2001, 21: [ 6 ] Zhou H uaiw u ( ). M athem atical statistics ( ) [M ]. J inan ( ) : Shandong Educational P ress ( ), [ 7 ] Do rozhk in J R. Surface reactions of apatite disso lution [J ]. J Co llo id interf Sci, 1997, 191: [ 8 ] M eurm an J H, H arkonen M, N averi H, et a l. Experim ental spo rts drinks w ith m inim al ero sive effect [ J ]. Scandinavian Journal of D ental Research, 1990, 98: [ 9 ] Yue Songling ( ). M odern caries ( ) [M ]. Beijing ( ) : Beijing M edical U niversity P ress ( ), [10 ] Johansson A K, So rvari R, B irkhed D, et al. D ental ero sion in deciduous teeth2an in vivo and in vitro study [J ]. Journal of D entistry, 2001, 29: [11 ] D ing Suidong ( ). F racture D ynam ics ( ) [M ]. Beijing ( ) : Ch ina M achanical Industry P ress ( ), [12 ] Kong Yongfa ( ), Gong J ianghong ( ), Yang Zhengfang ( ). W ear of structural ceram ic ( ) [J ]. J of Ch inese Ceram ic Society ( ), 1998, 17: [13 ] Dogan C P, H aw k J A. M icro structure and abrasive w ear in silicon nitride ceram ics[j ]. W ear, 2001, 250: Fr iction and W ear Behav ior of Human Enam el Eroded with D ifferen t Organ ic Ac ids Q IU Y i2nong 1, 3, L I Tong2sheng 2, L IU W ei2m in 1, L IU L an2zhong 3 (1. S tate K ey L aboratory of S olid L ubrication, L anz hou Institu te of Chem ical P hy sics, Ch inese A cad em y of S ciences, L anz hou , Ch ina; 2. T he K ey L aboratory of M olecu lar E ng ineering of P olym ers, M inistry of E d ucation, S hang hai , Ch ina; 3. D ep artm ent of S tom atology, L anz hou General H osp ital, L anz hou Comm and PL A, L anz hou , Ch ina) Abstract: T he friction and w ear behavio r of 56 hum an enam el samp les eroded w ith differen t o rgan ic acids w ere investigated by sliding again st artificial po rcelain teeth on an Op timo l SRV o scillating friction and w ear test rig, u sing a syn thetic saliva as the lub rican t m edium. T he w ear vo lum e lo ss data w ere analyzed statistically. T he w ear scars of the enam el of the hum an too th ob served w ith a scann ing electron m icro scope and the elem en t concen tration s of Ca and P w ith in and ou t of the w ear scars w ere determ ined w ith energy dispersion spectrom etry. T he co rrelation among the w ear behavio r and the hardness and toughness of the enam el samp les w as discu ssed as w ell. A s the resu lts, the samp les gave h igher w ear vo lum e lo ss after eroded w ith the acids than imm ersed w ith distilled w ater, excep t that the one eroded w ith m alic acid of ph 4. 0 had a sm aller w ear vo lum e lo ss. T he lactic acid resu lted in the largest enam el w ear vo lum e lo ss, fo llow ed w ith the citric acid and m alic acid at a ph value of 4. 0 (p < 0. 05), bu t they show ed no sign ifican t difference at a ph value of T he enam els eroded w ith the o rgan ic acids w ere m ain ly characterized by ab rasive w ear and m icro crack ing. T he difference of w ear data w as attribu ted to the differen t co rro sive ab ility of the acids w h ich led to differen t action s to the m echan ical strength of the enam els and had little difference w ith decreasing ph va lue. T hough the w ea r2resistance of the enam els w a s rela ted to the ha rdness and fractu re toughness, it m igh t depend on variou s o ther facto rs as w ell. Key words: hum an enam el; o rgan ic acid; ero sion; w ear behavio r Author: Q IU Y i2nong, m ale, bo rn in 1971, L ectu rer, e2m ail: qiuyinong@vip. sina. com.