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An amplifier-graphic recording method for measuring enamel permeability
RESEARCH .
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AMPLIFIER-GRAPHIC
ENAMEL
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RECORDING
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METHOD
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MEASURING
PERMF,ABILITY
withiu ~7 c~rmmel shell immersed in an electrolyte solution as ~7function of In order to increase the n.cc77l.ilcy ant1 the ntility 01’ this time of immersion. mcthoil. an :u~l])lific~l~-gt’;ll~hic rcaordvr has l~ten sulJstitutct1 for the c~ontlndThe ;llnl)lific~t.-1~c~(~(~~~~lit7g nl)l);lI*Rt77S ilnct! hridgcb used in t.he previous stutlg. has t.he il(l\r;l.l7tag(‘s of (1) allowing tlirect, ot)jcct,ive meas77rement oI’ conductmlcc~, iilltl thus of permeability changes ; (2) ]brovitli~7g ;1 cicmtinuons. pe7vnancM record of conduct:nlcc changes occurring tluring any tlesirctl interval of t,ime ; ant1 (3) good scasitivity to minute c~cnxluct ancv c2hanyc.s. In this article we will dcscrihe the apparatus anal denlonstr:7tr its utility ror tnc~asuring the chttngcs in enamel l)ernlei7l)ility brought nl~o77t 1)~ ilz(lnts known to nffect enamel permt~nhilit~. .\l’r’.\HATI-H
l’he ;11)1)arnt77sis shown in Fig. 1. The condncta7icc? cell (.I) is fahricatcvl two test tubchs of different diameters from which thv ldtoms have Iwell wrno\-ed. The tooth is cemented to the smaller test. tnlxl with Plicene ctwt+M. l’hc larger txst tube, when cemented to the sm:lllcr ()nv. scr~‘s as i7 dulml)er in which solutions are l)lac?cd so as t.o l)e in contact. with the cna~inel s77rface. TWO platinum wire (~lWtl"Od~lS~ il~~~~l’O~illlilt~~l~ :N 111111. IOllg. st~a.l)iliard 11y a plastic-c~ovclre(l cork, are l)laceil in tlic* smaller test tol)r ;ui(l heltl in plnnc with nnothcr plasticized cork. The conducta.ncc ~11 is mounted on an oscillating platform (73). 1’17~ elect,t*ic iiiot.or (r/l) causes the platform to 7aotate thv rond7lc+7nvr ~11 460 from
AMPLIFIER-GRAPHIC
RECORDING
METHOD
613
degrees end-over-end once every ten seconds. A4 mercury switch is attached t.o the platform, so that it connects the cell electrically for five seconds of each tt:n-second period. The oscillating platform thus serves to (1) provide a homogeuous solution around the electrodes, (2) minimize the generntion of heat within t.he smaller test tube since current flows bctwecn the electrodes only during the time the mercury switch is closed, and (3) provide for the tleflect.ion type of recording in which the magnitude of cat&h deflection iI)dicatcs directly the conductance of the system at that time. Idcads from the cdl clcctrodes are at.tachcd to the amplifier (Dj, and t.ho unit is powered from a 115 volt outlet. Transformer E reduces line volt.agc for the motor (C), and transformer F is in the amplifier power supply. The range and sensit.ivity of the amplifier are adjusted by potentiometers (C ant1 IT). A calibration source is indicated at. I. The amplifier output (Esterline-Angus graphic ammeter Model AW, Estcrlinc-Angus Co., Inc., Indianapolis, Indiana) activates the writing stylns (K) on the graphic recorder (J) . The graph paper moves through the recordrr at a constant speed. Each chart. contains sis deflections per minute of paper advance, eaeli rorrespondin g to a t.en-second period of the oscillating platform. The apparatus consistently detected and recorded conductance changes produced by as little as 3 s 1.0-Omolar sodium chloride solution. This was determined by measuring the relative conductance of twenty-four sodium chloride solutions ranging in concentration from 38 to 39,325 micromolar. The conductivity of t,he distilled water in which the electrodes were immersccl was determined, and then the conductances of progressively more concent rated sodium chloride solutions were measured. The relative conductance units (RCU), which vary from a value of 1.00 when a 38 pm sodium chloride solut,ion was used t.o a value of 3-l.50 when a 39,325 pm solution \Yils used. int1icat.c the ilttl~)litud(! of the writing stylus l~otlucc~l on the fifty-line rc-acot*Llin g pi1 per. It was shown previously’ that the cement (Cenco I’licene Ko. 114-21i used to attach the tooth to t.he conductance cell was impermeable to sodium and chloride ions during a sevent,v-minute period of immersion in a 25~1 sodium chloride solution. However, becauset.he physical qualit.& of t.he different batches of cetncnt, cspccially workability and flow, were found to differ and because the cement was to be esposcd to sodium chloritle solutions for longer time itltcrvnls, it. was necessary to re-evaluate certain properties of this cement. A cetncM shell was prepared and attached to the conductance cell. The conductancc of the distilled wat.er within the shell was recorded while the shrll was iattnersetl first in tlistilled water mtcl then in 2.531 sodium chloride solution for threcr houtx. These t~ccords show that the ccbttIcnt VJY~ISin~pernlc?;~l)l~~ to sodium and chloric‘lc ions and, in addition, tlt;lt ltclithcr the glass nscbdto const.t*uct: the contluc~attw ~11 nor the cement; itself was a sours of ions which would intcrfcre with permeability mcnsurenlcnls. 1Vhen the Iwic~tl of immersion was lengthenrtl to twelve hnurs, similar results were obt;linctl.
614
RREWER.
,4ND
MMUHLEX
F~PFRIYFsT A1 A A
Secl;ions of enamel prepared -from human teeth and from crowns of tlt~* ttta.ttdil~ular cuspids of dogs WWP usrd in testing thlx a,mplific~r-l,ecclrtlitt~ method of measuring ettitmei pet*trtcability. The htttnatt teeth were ~~lacrd in ilistillccl mater immrdiately i1ftPl’ l)Xt MCt,iOIl. One or si~vrral cti;umel s~(iCons werib prepared frcbttt it single tooth Ity s&iottittg with a diantontl disk during immersion in distilled water. The snt3nce of t.he enantel ws.s polishotl in a ruhhcr cup with flour 01’ ptttttice. ‘l’hc! t.hictkness of the tw:c!nt.y-fire diffcrrttt sections varied less l-halt 0.1 mm. Thlb sections wi’re cemental t.0 the cottductance cell. atttl t.hc perttt(~it!)ility of each section to ?.‘,M sotlittttt chloride was measured aftcr a cconirol t-(1st in distilled water. The duration of itnmersion in ckach solutiott was three hours. Manditn~1a.r c*nspitls W~I*C c~stt*act,ed itt toto ft~ttt tttongrcl clogs. The teeth were washed in distilled water and sectioned transversely ahont 2 mnt. l~low thtn cc~metttoc~ttattt(ll junction, ‘I’hlb CIWW~ISwere attachctl to the WIItlnctance Ccl1 n.s pt*e~ionsly clescrittetl il I’t.iht* heitig 1)olishcd with pumice 11) thla met.hod drscrihed for htttttittt treth. Thr permea.l)ility c>t’ ~otttt*aliti 01x1 tttitttdiltulitr cuspids ft’ortt four tl~g~ WRS ileterttiincd by ittttttet~siott itt 2.OM sotliattt ehloritlc solutiott for tight. hours. The tnandilmlat~ cusl)itls front three of thcne same animals and those f~*ont ;tnothet* dog WWP tt*citted with >I I l)(‘t* pchttt solution of sodium Auoritle or a 2 per ccttb stattttous fluoride solution antI then reimmersed in 2.031: sodium chloride for varying intervttls of timr itt order that the effect 01 fluorides on the 1tertne;tI)ility of the trcsth might, he studied.
The tlnta ott the permeability of t.wenty-fi\-cl se&ions of human t.ecth 1-o 2.5tiI sodium chloride show 11 marked \lariahility in ettatnel p~~rtttc~ahility of diffcrcnt teeth (Table 1’). Those findings ronfirttx onr previous data’ snpS&ions gesting aoitsidnt7thl~~ r:t ttclottt v;t.rialtility itt i!ttntttel pl~t*ltlcilltility. of etlattlel which cottt.aincd small (various dl!frcts are more prrtnealtle th:ttt Similnr findittgs hare lx~t other sections preparc~l front l-hc sHrtt(’ tooth. r~~portcd previously l)y l:c,ust,:L who fouttcl that curious t&h wore ntor(’ pertneahle than noncations leeth to alcoholic* ttasil~ fuchsitt. l!eust attrilmtetl the increased pcrmcbahility of the ca.t*ious Icsiott to “a loose ntolibc*ular struCture. ” Although thlb age OF the I);ttiettt ft~nt whom the teeth were ohtaittiLiI was not known in all instances. c~tt;t.tnc~lpl~rnteahility appcats I o ~WJWIW~ with age, as previously reported by At.kinsonq and ‘I’ish.S Mt~asurernertt of the thickttckss of the (attittttcl srations showed that this .fnct.or did not. es])laitt the variations olx~r~crl itt tt111pc~rtrtcAility of clifferc!ttt. sections. AetIlall~, some ()I’ the t.hittttcbst s&ions were completely irttperme;t.hle to sodium it,tt(l trhloridn ions. The results ol)taitlecl ftwn me;tsuring thlb pa~tmteability of codrtthtet’it 1 mandibular cuspids from the same dog show that the total conduct,atxe change is directly related to the time during which the tooth is immersed
Volume Numhr
I4 <
AMPLIFIER-GRAPIITC
RECOR~DING
XETFIOI,
615
the sodium chloride solution and int1icat.e that thcrc are wide variatiolis 1”0r c~s;I~~~~)Ic.t hr total ~otl(lu~tatl(?~~ in the permeabilities of different t.ceth. (!han~~ in hhc right m;lndilml;lr euq&l of (10g x1 WAS o~~IY 3.8 RC’I, wh(lr(bi,s the right I~li~~l(lil)ulilr cuspit Al’ (log ( ’ SIIOWHI il. (~~~lltI~l(*t~t~l(~~(*hilllg(l of the ~~el~rllc~ilI)ilitic~s Of ~Olltl*iI12.8 R,(‘I- for thth s;ime time pc~riotl. IIoWckvc~r, lateral cusl)itls frow the same ilog wew similar. 1‘11~ similarity ill thr I)t’rlnc~;lI)ility of co~ltralil.te~~ill treth has ~ISO II(v~~I r(‘l)orte(l 1)~ J-:&grrc~n.” \v110 ~~)~~~~~~~t~~d the p(‘r~tlc~;lhilit~ of ~~~~~~tralat~~t~~~l t10g cuspitls to dyes.
in
That the actual passage of ions through the tooth is measured 1)~ the amplifier-recorder was dcmonst.ra.ted ly immersing one OF the dog cwpids in three successive changes of distilled water following immersion in sodium ahloridc. Thtxc data. ase plotted in Fig. 2. It is interesting to notr that soluhlc ions Rrv present in the extracted tooth and that the movement of these hto the pulp chamber is of dctx~ctahle magnitude, as intlicatctl hy trial L4. Also of interest. is a comparison of t,he data from trials T3 ant1 (‘. ‘Pkl I: shows the effect on conductance of immersing the tooth ill sodium chloritl(b, and in this particular tooth increases in t.ime and c*ontluctancr ar(’ almost linearly related. The conductance changes in trial C ar( clucl to ions r(qnaitling in the tooth after immersion in sodium chloride, since the condnct.ance changes that occurred are greater in t.rial C than in trial A. The sipnificanccl of t.hc apparently grcatcr rate of conduct.ance change in t.riaI (!, wh(ln th,,
1.0 1.3 1.0
0.0 0.5 0.3 Il.5 I .3 0.5
19.0 -wJ 22.0 1'8.1) -5 Ti "2 2.2 :1:3 4.5 ti.i 2.3 2.0 1.3 I .o 1.1 0.6 0.x 03 0.0 0.11 2.II 3.10 " I.1 _-- .__.-. 1.L._. --.
.;,O.II 29.0 ," 2 ;::i !I.0 3 .'
2:;
‘I .:!
1.i) 1.0 xs I.-l .-.. -.
3.0 15.6 4.x .I 2 0 3:X 2.x , 0
1:; 1Sl 4.C I .5
22, A 8 C 0 E
Did. H,O 2M NaCl Did. H,O l ’ ’ l
8. 6-
2 4 6 8 IO I2 TIME OF IMMERSION OF TOOTH IN DIFFERENT SOLUTIONS( hrs.) Fig. P.-Graph illustrating the conductance changes within the pulp chamber of a doe’s cuspid when immersed successively in distilled water (A) : in 2M NaCl solution (B) ; and in thret? changes of distilled water (C. II. and E ).
7.2 I .i.O +.5 ::.s I .:1 I.3 1..i .i.T, 1.R
,4MPJ,IFIER--GRAPHIC
Volume 14 Number 5
FLUORIDEON PER~IE~BILITY OF MANDIBULAR CIXPIDS =-HALF-HOUR
INTERVALS
IMYER5ION
29.0 87.0
29.0 29.5
29.5 33.0
10.4 I 8.n
12.3 '0.5
15.8 22.8
20.0
“1.8
25.2
5.0 5.0
523 Ii.8 2.2
Il.0 10.0 3.4
,;.; 4:1
28.5 8.0 16.8 7.6
9.5 12.0 9.4
2.5
7.0
2.0
---_---
3.5
Ii.0
4.0 7.8
7.2 8.8
2.1
2..7
2.i
OF
IN ELECTROLYTE
29.0 24.0
'7.n 00 -.
---_
DURING
RECORDING
29.0 35.2
METHOD
DOGS
-..---.-. -..---._
29.0 40.2 25.5 34.0 9.5
09.0 43.0
15.0 19.0
21.0 11.2 20.5 25.0
25.0 15.0
10.8
11.7
“9.3 18.6 31.0 32.5 14.0
3.2
.--. .
SOLUTION
29.0 39.0 23.2 31.5 8.5
3.0
617
26.0
28.5 12.8 3.5
9.0 :x.0 10.;
4.0 ___.__
29.0 44.5 27.0 39.0 12.0
29.0 46.8 27.0 -IO.8 12.8
29.0 49.0 3.0 42.5 15.0
X3.2 “53
364 26.5
40.0 30.5
36.5
41.5
45.5
38.0 15.4
41.x Ii.2
Ji.0
4.4 ---_-.---
5.0
1x.5 ---..
6.N .-..
tooth W:IS immersed in distilled water, than in trial B, whew t.he tooth was itnmersctl in sodium chloride, is not clear. The data from trial D indicate continued movement of ions into the pulp chamber of the tooth, whereas it1 trial E the total mass of inns which entered the tooth during its immcarsion in sodium chloride has been wtuored. Tti order to d(lmonstratc the utility of the met.hocl and to prcwtlt data ol)tainc(l through the use of thwe tcchniquw which can be compared with Iwevious studies in which diffcrcnt techniques were employed, a comllarisotl of the sntisolubility cffectivcness of stannous fluoride was madr. Tn 21 previous article’ it wa.s report.cd that the topical treatment of cnnmel with statlnous fiuoridc resulted in a greater decrease in etlamcl permeability t.han similar ena.mel treat.ment with sodium fluoride. ln the earlier inr-cstigation thcb enam(4 was esposctl to the fluoride solution Pot* I'our minutes and then imnwrsed in sodium chloride fo7’ sewnty iiiiuutcs. 171 t.he present study the topical fluoride t.reatments lastecl for tw minutes for each tooth, after which the twth were immediately immersed in sodium chlorid(~ aud the conductance! \vas r~wrclecl for twelw hours. The data in Tab1.e II confirm the finclings of the prwious study and, more important! indicate (1.) t.hat the effcct.iveness of the fluoride solut.ion in decreasing enamel permeability is a function OI the time of csposnrc of the toot.h to the fluoride solution and (2) that, tllct pc?l.mea.bility-~etlucillg effect of stannous fluoride lasts for several houw.
,411 amplifier-graphic recorder for measuring (‘1lil771(‘1 ~~wnicahility 1la.s been described. Some characteristics of this apparatus have been demonstrated. Data obtained on the permeability of human and dog enamel havr been presented to indicate the method’s utility.
1. Brewer, H. IL, Muhler, J. C., anal Fischer, B. 13.: Effects of l*‘luoridcs on t.he Permeability of Human Dental Enamel to Inorganic Ions, J. D. Res. 35: 59, 1956. 2. The Esterlinc-Angus Co., Inc.: The Graphic Bulletin, No. ;?Wh, Indianapolis, 1955. TIII~ Esterline-Angus Company, Inc.
3. Bcust T B . Permea‘tdi1.y Tests on Teeth With Pulpal Involwment, .I. I). Res. 18: !C. . ‘I& .* An Investigation into the Permeability of Human Enamel l;nin:: 4. Atkinson, H. F.: Osmotic Methods, Brit. I). J. 83: ZOB, 1947. Age Changes in the Permeability of l)og Enamel, J. Physiol. 72: Xl, 5. J&h, 115.W.: 1991. of Enamel and Drntuw, 6. Rtvgrrt!ll, IT. : Experimental Studies OII 1111%Pernlwlditp HwtltliRh
Dent.
.T. 40:
So.
lK,
lW7.
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AN
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AMPLIFIER-GRAPHIC
ENAMEL
.
.
.
.
.
RECORDING
.
.
.
.
METHOD
.
.
FOR
.
.
.
.
.
MEASURING
PERMF,ABILITY
withiu ~7 c~rmmel shell immersed in an electrolyte solution as ~7function of In order to increase the n.cc77l.ilcy ant1 the ntility 01’ this time of immersion. mcthoil. an :u~l])lific~l~-gt’;ll~hic rcaordvr has l~ten sulJstitutct1 for the c~ontlndThe ;llnl)lific~t.-1~c~(~(~~~~lit7g nl)l);lI*Rt77S ilnct! hridgcb used in t.he previous stutlg. has t.he il(l\r;l.l7tag(‘s of (1) allowing tlirect, ot)jcct,ive meas77rement oI’ conductmlcc~, iilltl thus of permeability changes ; (2) ]brovitli~7g ;1 cicmtinuons. pe7vnancM record of conduct:nlcc changes occurring tluring any tlesirctl interval of t,ime ; ant1 (3) good scasitivity to minute c~cnxluct ancv c2hanyc.s. In this article we will dcscrihe the apparatus anal denlonstr:7tr its utility ror tnc~asuring the chttngcs in enamel l)ernlei7l)ility brought nl~o77t 1)~ ilz(lnts known to nffect enamel permt~nhilit~. .\l’r’.\HATI-H
l’he ;11)1)arnt77sis shown in Fig. 1. The condncta7icc? cell (.I) is fahricatcvl two test tubchs of different diameters from which thv ldtoms have Iwell wrno\-ed. The tooth is cemented to the smaller test. tnlxl with Plicene ctwt+M. l’hc larger txst tube, when cemented to the sm:lllcr ()nv. scr~‘s as i7 dulml)er in which solutions are l)lac?cd so as t.o l)e in contact. with the cna~inel s77rface. TWO platinum wire (~lWtl"Od~lS~ il~~~~l’O~illlilt~~l~ :N 111111. IOllg. st~a.l)iliard 11y a plastic-c~ovclre(l cork, are l)laceil in tlic* smaller test tol)r ;ui(l heltl in plnnc with nnothcr plasticized cork. The conducta.ncc ~11 is mounted on an oscillating platform (73). 1’17~ elect,t*ic iiiot.or (r/l) causes the platform to 7aotate thv rond7lc+7nvr ~11 460 from
AMPLIFIER-GRAPHIC
RECORDING
METHOD
613
degrees end-over-end once every ten seconds. A4 mercury switch is attached t.o the platform, so that it connects the cell electrically for five seconds of each tt:n-second period. The oscillating platform thus serves to (1) provide a homogeuous solution around the electrodes, (2) minimize the generntion of heat within t.he smaller test tube since current flows bctwecn the electrodes only during the time the mercury switch is closed, and (3) provide for the tleflect.ion type of recording in which the magnitude of cat&h deflection iI)dicatcs directly the conductance of the system at that time. Idcads from the cdl clcctrodes are at.tachcd to the amplifier (Dj, and t.ho unit is powered from a 115 volt outlet. Transformer E reduces line volt.agc for the motor (C), and transformer F is in the amplifier power supply. The range and sensit.ivity of the amplifier are adjusted by potentiometers (C ant1 IT). A calibration source is indicated at. I. The amplifier output (Esterline-Angus graphic ammeter Model AW, Estcrlinc-Angus Co., Inc., Indianapolis, Indiana) activates the writing stylns (K) on the graphic recorder (J) . The graph paper moves through the recordrr at a constant speed. Each chart. contains sis deflections per minute of paper advance, eaeli rorrespondin g to a t.en-second period of the oscillating platform. The apparatus consistently detected and recorded conductance changes produced by as little as 3 s 1.0-Omolar sodium chloride solution. This was determined by measuring the relative conductance of twenty-four sodium chloride solutions ranging in concentration from 38 to 39,325 micromolar. The conductivity of t,he distilled water in which the electrodes were immersccl was determined, and then the conductances of progressively more concent rated sodium chloride solutions were measured. The relative conductance units (RCU), which vary from a value of 1.00 when a 38 pm sodium chloride solut,ion was used t.o a value of 3-l.50 when a 39,325 pm solution \Yils used. int1icat.c the ilttl~)litud(! of the writing stylus l~otlucc~l on the fifty-line rc-acot*Llin g pi1 per. It was shown previously’ that the cement (Cenco I’licene Ko. 114-21i used to attach the tooth to t.he conductance cell was impermeable to sodium and chloride ions during a sevent,v-minute period of immersion in a 25~1 sodium chloride solution. However, becauset.he physical qualit.& of t.he different batches of cetncnt, cspccially workability and flow, were found to differ and because the cement was to be esposcd to sodium chloritle solutions for longer time itltcrvnls, it. was necessary to re-evaluate certain properties of this cement. A cetncM shell was prepared and attached to the conductance cell. The conductancc of the distilled wat.er within the shell was recorded while the shrll was iattnersetl first in tlistilled water mtcl then in 2.531 sodium chloride solution for threcr houtx. These t~ccords show that the ccbttIcnt VJY~ISin~pernlc?;~l)l~~ to sodium and chloric‘lc ions and, in addition, tlt;lt ltclithcr the glass nscbdto const.t*uct: the contluc~attw ~11 nor the cement; itself was a sours of ions which would intcrfcre with permeability mcnsurenlcnls. 1Vhen the Iwic~tl of immersion was lengthenrtl to twelve hnurs, similar results were obt;linctl.
614
RREWER.
,4ND
MMUHLEX
F~PFRIYFsT A1 A A
Secl;ions of enamel prepared -from human teeth and from crowns of tlt~* ttta.ttdil~ular cuspids of dogs WWP usrd in testing thlx a,mplific~r-l,ecclrtlitt~ method of measuring ettitmei pet*trtcability. The htttnatt teeth were ~~lacrd in ilistillccl mater immrdiately i1ftPl’ l)Xt MCt,iOIl. One or si~vrral cti;umel s~(iCons werib prepared frcbttt it single tooth Ity s&iottittg with a diantontl disk during immersion in distilled water. The snt3nce of t.he enantel ws.s polishotl in a ruhhcr cup with flour 01’ ptttttice. ‘l’hc! t.hictkness of the tw:c!nt.y-fire diffcrrttt sections varied less l-halt 0.1 mm. Thlb sections wi’re cemental t.0 the cottductance cell. atttl t.hc perttt(~it!)ility of each section to ?.‘,M sotlittttt chloride was measured aftcr a cconirol t-(1st in distilled water. The duration of itnmersion in ckach solutiott was three hours. Manditn~1a.r c*nspitls W~I*C c~stt*act,ed itt toto ft~ttt tttongrcl clogs. The teeth were washed in distilled water and sectioned transversely ahont 2 mnt. l~low thtn cc~metttoc~ttattt(ll junction, ‘I’hlb CIWW~ISwere attachctl to the WIItlnctance Ccl1 n.s pt*e~ionsly clescrittetl il I’t.iht* heitig 1)olishcd with pumice 11) thla met.hod drscrihed for htttttittt treth. Thr permea.l)ility c>t’ ~otttt*aliti 01x1 tttitttdiltulitr cuspids ft’ortt four tl~g~ WRS ileterttiincd by ittttttet~siott itt 2.OM sotliattt ehloritlc solutiott for tight. hours. The tnandilmlat~ cusl)itls front three of thcne same animals and those f~*ont ;tnothet* dog WWP tt*citted with >I I l)(‘t* pchttt solution of sodium Auoritle or a 2 per ccttb stattttous fluoride solution antI then reimmersed in 2.031: sodium chloride for varying intervttls of timr itt order that the effect 01 fluorides on the 1tertne;tI)ility of the trcsth might, he studied.
The tlnta ott the permeability of t.wenty-fi\-cl se&ions of human t.ecth 1-o 2.5tiI sodium chloride show 11 marked \lariahility in ettatnel p~~rtttc~ahility of diffcrcnt teeth (Table 1’). Those findings ronfirttx onr previous data’ snpS&ions gesting aoitsidnt7thl~~ r:t ttclottt v;t.rialtility itt i!ttntttel pl~t*ltlcilltility. of etlattlel which cottt.aincd small (various dl!frcts are more prrtnealtle th:ttt Similnr findittgs hare lx~t other sections preparc~l front l-hc sHrtt(’ tooth. r~~portcd previously l)y l:c,ust,:L who fouttcl that curious t&h wore ntor(’ pertneahle than noncations leeth to alcoholic* ttasil~ fuchsitt. l!eust attrilmtetl the increased pcrmcbahility of the ca.t*ious Icsiott to “a loose ntolibc*ular struCture. ” Although thlb age OF the I);ttiettt ft~nt whom the teeth were ohtaittiLiI was not known in all instances. c~tt;t.tnc~lpl~rnteahility appcats I o ~WJWIW~ with age, as previously reported by At.kinsonq and ‘I’ish.S Mt~asurernertt of the thickttckss of the (attittttcl srations showed that this .fnct.or did not. es])laitt the variations olx~r~crl itt tt111pc~rtrtcAility of clifferc!ttt. sections. AetIlall~, some ()I’ the t.hittttcbst s&ions were completely irttperme;t.hle to sodium it,tt(l trhloridn ions. The results ol)taitlecl ftwn me;tsuring thlb pa~tmteability of codrtthtet’it 1 mandibular cuspids from the same dog show that the total conduct,atxe change is directly related to the time during which the tooth is immersed
Volume Numhr
I4 <
AMPLIFIER-GRAPIITC
RECOR~DING
XETFIOI,
615
the sodium chloride solution and int1icat.e that thcrc are wide variatiolis 1”0r c~s;I~~~~)Ic.t hr total ~otl(lu~tatl(?~~ in the permeabilities of different t.ceth. (!han~~ in hhc right m;lndilml;lr euq&l of (10g x1 WAS o~~IY 3.8 RC’I, wh(lr(bi,s the right I~li~~l(lil)ulilr cuspit Al’ (log ( ’ SIIOWHI il. (~~~lltI~l(*t~t~l(~~(*hilllg(l of the ~~el~rllc~ilI)ilitic~s Of ~Olltl*iI12.8 R,(‘I- for thth s;ime time pc~riotl. IIoWckvc~r, lateral cusl)itls frow the same ilog wew similar. 1‘11~ similarity ill thr I)t’rlnc~;lI)ility of co~ltralil.te~~ill treth has ~ISO II(v~~I r(‘l)orte(l 1)~ J-:&grrc~n.” \v110 ~~)~~~~~~~t~~d the p(‘r~tlc~;lhilit~ of ~~~~~~tralat~~t~~~l t10g cuspitls to dyes.
in
That the actual passage of ions through the tooth is measured 1)~ the amplifier-recorder was dcmonst.ra.ted ly immersing one OF the dog cwpids in three successive changes of distilled water following immersion in sodium ahloridc. Thtxc data. ase plotted in Fig. 2. It is interesting to notr that soluhlc ions Rrv present in the extracted tooth and that the movement of these hto the pulp chamber is of dctx~ctahle magnitude, as intlicatctl hy trial L4. Also of interest. is a comparison of t,he data from trials T3 ant1 (‘. ‘Pkl I: shows the effect on conductance of immersing the tooth ill sodium chloritl(b, and in this particular tooth increases in t.ime and c*ontluctancr ar(’ almost linearly related. The conductance changes in trial C ar( clucl to ions r(qnaitling in the tooth after immersion in sodium chloride, since the condnct.ance changes that occurred are greater in t.rial C than in trial A. The sipnificanccl of t.hc apparently grcatcr rate of conduct.ance change in t.riaI (!, wh(ln th,,
1.0 1.3 1.0
0.0 0.5 0.3 Il.5 I .3 0.5
19.0 -wJ 22.0 1'8.1) -5 Ti "2 2.2 :1:3 4.5 ti.i 2.3 2.0 1.3 I .o 1.1 0.6 0.x 03 0.0 0.11 2.II 3.10 " I.1 _-- .__.-. 1.L._. --.
.;,O.II 29.0 ," 2 ;::i !I.0 3 .'
2:;
‘I .:!
1.i) 1.0 xs I.-l .-.. -.
3.0 15.6 4.x .I 2 0 3:X 2.x , 0
1:; 1Sl 4.C I .5
22, A 8 C 0 E
Did. H,O 2M NaCl Did. H,O l ’ ’ l
8. 6-
2 4 6 8 IO I2 TIME OF IMMERSION OF TOOTH IN DIFFERENT SOLUTIONS( hrs.) Fig. P.-Graph illustrating the conductance changes within the pulp chamber of a doe’s cuspid when immersed successively in distilled water (A) : in 2M NaCl solution (B) ; and in thret? changes of distilled water (C. II. and E ).
7.2 I .i.O +.5 ::.s I .:1 I.3 1..i .i.T, 1.R
,4MPJ,IFIER--GRAPHIC
Volume 14 Number 5
FLUORIDEON PER~IE~BILITY OF MANDIBULAR CIXPIDS =-HALF-HOUR
INTERVALS
IMYER5ION
29.0 87.0
29.0 29.5
29.5 33.0
10.4 I 8.n
12.3 '0.5
15.8 22.8
20.0
“1.8
25.2
5.0 5.0
523 Ii.8 2.2
Il.0 10.0 3.4
,;.; 4:1
28.5 8.0 16.8 7.6
9.5 12.0 9.4
2.5
7.0
2.0
---_---
3.5
Ii.0
4.0 7.8
7.2 8.8
2.1
2..7
2.i
OF
IN ELECTROLYTE
29.0 24.0
'7.n 00 -.
---_
DURING
RECORDING
29.0 35.2
METHOD
DOGS
-..---.-. -..---._
29.0 40.2 25.5 34.0 9.5
09.0 43.0
15.0 19.0
21.0 11.2 20.5 25.0
25.0 15.0
10.8
11.7
“9.3 18.6 31.0 32.5 14.0
3.2
.--. .
SOLUTION
29.0 39.0 23.2 31.5 8.5
3.0
617
26.0
28.5 12.8 3.5
9.0 :x.0 10.;
4.0 ___.__
29.0 44.5 27.0 39.0 12.0
29.0 46.8 27.0 -IO.8 12.8
29.0 49.0 3.0 42.5 15.0
X3.2 “53
364 26.5
40.0 30.5
36.5
41.5
45.5
38.0 15.4
41.x Ii.2
Ji.0
4.4 ---_-.---
5.0
1x.5 ---..
6.N .-..
tooth W:IS immersed in distilled water, than in trial B, whew t.he tooth was itnmersctl in sodium chloride, is not clear. The data from trial D indicate continued movement of ions into the pulp chamber of the tooth, whereas it1 trial E the total mass of inns which entered the tooth during its immcarsion in sodium chloride has been wtuored. Tti order to d(lmonstratc the utility of the met.hocl and to prcwtlt data ol)tainc(l through the use of thwe tcchniquw which can be compared with Iwevious studies in which diffcrcnt techniques were employed, a comllarisotl of the sntisolubility cffectivcness of stannous fluoride was madr. Tn 21 previous article’ it wa.s report.cd that the topical treatment of cnnmel with statlnous fiuoridc resulted in a greater decrease in etlamcl permeability t.han similar ena.mel treat.ment with sodium fluoride. ln the earlier inr-cstigation thcb enam(4 was esposctl to the fluoride solution Pot* I'our minutes and then imnwrsed in sodium chloride fo7’ sewnty iiiiuutcs. 171 t.he present study the topical fluoride t.reatments lastecl for tw minutes for each tooth, after which the twth were immediately immersed in sodium chlorid(~ aud the conductance! \vas r~wrclecl for twelw hours. The data in Tab1.e II confirm the finclings of the prwious study and, more important! indicate (1.) t.hat the effcct.iveness of the fluoride solut.ion in decreasing enamel permeability is a function OI the time of csposnrc of the toot.h to the fluoride solution and (2) that, tllct pc?l.mea.bility-~etlucillg effect of stannous fluoride lasts for several houw.
,411 amplifier-graphic recorder for measuring (‘1lil771(‘1 ~~wnicahility 1la.s been described. Some characteristics of this apparatus have been demonstrated. Data obtained on the permeability of human and dog enamel havr been presented to indicate the method’s utility.
1. Brewer, H. IL, Muhler, J. C., anal Fischer, B. 13.: Effects of l*‘luoridcs on t.he Permeability of Human Dental Enamel to Inorganic Ions, J. D. Res. 35: 59, 1956. 2. The Esterlinc-Angus Co., Inc.: The Graphic Bulletin, No. ;?Wh, Indianapolis, 1955. TIII~ Esterline-Angus Company, Inc.
3. Bcust T B . Permea‘tdi1.y Tests on Teeth With Pulpal Involwment, .I. I). Res. 18: !C. . ‘I& .* An Investigation into the Permeability of Human Enamel l;nin:: 4. Atkinson, H. F.: Osmotic Methods, Brit. I). J. 83: ZOB, 1947. Age Changes in the Permeability of l)og Enamel, J. Physiol. 72: Xl, 5. J&h, 115.W.: 1991. of Enamel and Drntuw, 6. Rtvgrrt!ll, IT. : Experimental Studies OII 1111%Pernlwlditp HwtltliRh
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