1.POWDER-CAIR RASIO DAN SIFAT DUA restoratif.doc

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Acta Odontol. Latinoam. 2011 ISSN 0326-4815 Vol. 24 N 2 / 2011 / 200-204

RESUMEN

Las modificaciones en la relacin polvo-lquido de los cemen-

tos de ionmero vtreo podran afectar algunas de sus

propiedades fsicas y su erosin cida.

El objetivo de este trabajo fue evaluar las propiedades fsicas

y la erosin cida de dos cementos de ionmero vtreo para

restauracin, segn la orma !"# $$%&-%'())&, luego de mod-

ificar la relacin polvo-lquido alcan*ando una consistencia

adecuada para fijar restauraciones rgidas."e aplic la metodologa de la orma !"# con una relacin

polvo-lquido segn indica el fabricante y una relacin modifi-

cada. "e evalu espesor de pelcula, resistencia compresiva,

tiempo de fraguado y erosin cida en dos cementos de

ionmero vtreo para restauracin' +emil +/ 0entsply/,

!onofil 1lus !1/ 2oco/. El espesor de pelcula fue determinado

con un micrmetro digital 0igimatic 3itutoyo +orporation/.

El tama4o de la muestra fue de 5 unidades para cada cemento

o condicin e6perimental. La resistencia compresiva !nstron

%)%%, velocidad del cabe*al % mm7min/ fue evaluada luego de

la inmersin en agua destilada a 8&9+. n:5. El tiempo de

fraguado se evalu a 8&9+. n:8. "e utili*aron soportes de pro-

beta 8) 6 8) 6 5 mm/ con una perforacin central de 5 mm de

dimetro y ( mm de profundidad para los ensayos de erosin

cida. La lectura de la profundidad de erosin de las probetas

fue reali*ada con un calibre con ).))% mm de precisin, antes y

despu;s de la inmersin durante (< oras en una solucin de

cido lctico-lactato de sodio con p= (.&< en estufa a 8&9+.n:5. La prueba de "tudent fue reali*ada con un nivel de signif-

icancia de p> ).)5 para cada material y condicin.

3edia ?ritm;tica 0esviacion Estndar/ @elacin polvo-lquido

segn el fabricante' espesor de pelcula en Am/' + (()


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compresiva a las (< s en 31a/' +' D$.8 %


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Argentina#. Ten minutes later, the overall thickness ofthe plates and the cement was recorded !>eading ?#.

The difference between readings A and ? !difference

between the thickness of the plates with and without

the material between them# was considered as the final

combined film thickness for the specimen being test-

ed. 5ample si2e was five for each cement or condition.

or each cement, ( + mm cylinders were made in

stainless steel moulds. Compressive strength was

evaluated after %(h immersion in distilled water at

&/7C, with an )nstron $achine 1311, with a crosshead

speed of 1 mm@min. :alues for compressive strength

were obtained in $4a by relating the applicationforce !'# to the cylinder surface !mm #. 5ample si2e%

was five for each cement or condition.

5etting time was evaluated for Chemfil and )onofil

4lus at &/7C. ne tenth of a milliliter of the cement

was placed in a metal mould with a central perforation

of 13 mm. 'inety seconds after the end of miing,

a metallic indentor with a flat end 1 mm in diameter

was applied vertically onto the surface of the cement

for + seconds. The indentations were repeated at thir-

ty-second intervals !in the first case# and at ten-second

intervals in the others, until the needle failed to make

a complete circular indentation in the cement. The

time elapsed between the end of miing and the timewhen the needle failed to indent the material was con-

sidered as setting time for the material tested. 5ample

si2e was three for each cement or condition.

Acid erosion was determined using &3 &3 + mm

specimen moulds with a central perforation of + mm in

diameter and % mm depth. rosion depth was measured

with a micrometer gauge with a precision of 3.331 mm,

before and after %( hour immersion in a lactic acid-sodium lactate solution with p< %./( at &/7C. ?oth

materials were tested with a powder-li"uid ratio as indi-

cated by the manufacturer and a modified ratio. 5am-

ple si2e was five for each condition and eperimental

conditions were compared using 5tudent*s t test.

RESULTS

Table & shows means and standard deviations as

well their 0+9 confidence intervals for the film

thickness, compressive strength, setting time and

acid erosion of the glass ionomer cements tested,

with a powder-li"uid ratio as indicated by the man-ufacturers and a modified ratio.

5tudent*s t test was performed for each material and

condition with a level of significance of pB 3.3+. The

difference between each condition tested was statisti-

cally significant !pB3.31# for film thickness and com-

pressive strength as shown by the lack of overlap of the

confidence intervals. hen the powder-li"uid ratio of

)onofil 4lus was modified, it did not meet the minimum

re"uired compressive strength specification !+3 $4a#.

5etting time was studied at &/DC with a powder-li"-

uid ratio according to manufacturers and a modified

ratio. )onofil 4lus did not meet the )5 5pecifica-

tion re"uirements for a luting cement when the pow-der-li"uid ratio was modified, because it eceeded

the E minutes maimum epected !0.&E min#. 5tu-

dent*s t test showed that the difference between each

material and condition tested was statistically sig-

nificant !pB3.31#, and that there were statistical dif-

ferences for both materials because of the lack of

overlap in the confidence intervals.

202 Vi*ian N. +a,a Sio '. o,n "icado L. (acc,i


Table 1. Products and Powder-Liquid Ratio used.

Type of Cement

Restoati!e g"ass ionome

Restoati!e g"ass ionome

Trade Name

C#em$i"

Iono%i" P"&s

Code

C#

IP

Powder - Liquid Ratio

'an&%a(t&e:).4:1'o*i%ie*:+.):1

'an&%a(t&e:,.1,:1'o*i%ie*:2.,):1

Manufacturer

entsp"

o(o

Batc

4808,

P:11188L:0142

Table !. "#$ %%1&-1'!((& Requirements for )lass "onomer Cements.

Type of material

Restoati!e

L&ting

*ilm Tic+ness,m

ma/.

-

2,

Compressi0e strent,MPa

min.

100

,0

Net settin time,minutes

min. ma/.

1.,

1., 8

2cid erosion,mm

ma/.

0.1)

0.1)

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The depth of acid erosion !mean and standard devia-

tion in mm# was evaluated for both materials. 5tu-

dent*s t test showed that the difference between each

condition tested for Chemfil was statistically signifi-

cant !pB3.31#. Chemfil did not meet the re"uirements

of )5 001/-16%33/ when the powder-li"uid ratio

was modified. ata were not recorded for )onofil 4lus

specimens when the powder-li"uid ratio was modi-

fied because the samples disintegrated in the solution.

DISCUSSION

Conventional glass ionomer cements are fre"uently

used in dental practice to restore or lute restorations

of dental and other structures 1,( because of its

advantages, such as fluoride ion release, physico-

chemical bonding to tooth structure and a low coef-

ficient of thermal epansion ./

The correct choice of a luting agent is key to suc-

cess in indirect dentistry and dependent on the clin-ical situation, based on its physical, biological and

handling properties ./

Changes in the powder-li"uid ratio of conventional

glass ionomer cements may alter some physical prop-

erties. ne of them is the film thickness, which depends

on multiple factors 1,%,,E,0,including manipulation, tem-

perature of the mi, consistency, handling, working

and setting time and time elapsed after miing 1,&,- ,E.

Consistency is considered one of the principal features

affecting the film thickness of any luting material. )nE

this study, when the powder-li"uid ratio was modified

to ade"uate consistency for a luting cement, both mate-

rials tested, Chemfil and )onofil 4lus met the %+ =mmaimum re"uired by )5 001/, as shown by the lack

of overlap of the confidence intervals.

Compressive strength has been used as a predictor

of clinical performance. or a restoration to func-

tion correctly, the cement must have sufficient

strength to resist fracture .?oth materials tested met1

)5 specifications regarding compressive strength

when the powder-li"uid ratio was used according to

manufacturers. n the other hand, )onofil 4lus did

not fulfill the re"ueriments when the modified pow-

der-li"uid ratio was used because it did not reach the

minimum value of +3 $4a. ne study has shown

that the compressive strength of encapsulated glassionomer cements which have high viscosity produce

more favourable mechanical properties. The reason&

was the lower probability of air inclusions during

the mechanical miing . )n contrast, more fluid(

materials produced lower porosity by hand miing

than by mechanical miing. )t appears that the lower

viscosity material more readily causes air inclusions

Po;d-li


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and a type of froth is formed during the rapid mi-

ing process. The slower hand-miing process helps

to avoid these inclusions and may cause the collapse

of the air-bubbles .&

'et setting time was evaluated at &/7C. ?oth

Chemfil and )onofil 4lus took longer to set !dou-ble# when the powder-li"uid ratio was modified.

This was more noticeable in )onofil 4lus. The set-

ting time of luting agents is influenced by temper-

ature. As temperature increases, the working and

setting times of glass ionomer cements decrease . 1

Although at &/7C !according )5 001/# the net set-

ting time of any luting material is epected to be

shorter than E minutes, )onofil 4lus eceeded the

specification values.

ifferent strategies have been developed to obtain

success in cementation because it depends on mul-

tiple factors1,+,E,0

. The luting procedure has thepotential to adversely influence marginal adapta-

tion , so the ability of the cement to withstand epo-0

sure to different media in the mouth , to avoid13

water sorption and dissolution, is essential to clini-

cal success . Acid erosion tests were carried out for(

both materials and conditions, but the results did

not meet the 3.1/ mm maimum re"uired for luting

materials according )5 5pecifications. )onofil 4lus

specimens with the modified powder-li"uid ratio

disintegrated a few minutes after immersion in the

lactic acid-sodium lactate solution.

$oreover, the acidity of the storage medium is not

the only factor responsible for the degradation ofcements. The ability to resist dissolution has been

found to vary with the composition of the medium,

and not simply with its p< . The acid erosion tests13

provided an idea of the performance of the two

restorative glass ionomer cements selected at ade-

"uate consistencies for luting restorations.

There is not a single specific material that could be

used for the entire range of procedures, but the cor-

rect luting agent must be selected according to its

mechanical and physical properties in order to

ensure high clinical performance1,%,(,/,E.

CONCLUSION

)t can be concluded that, while changes introduced

in the powder-li"uid ratio of a restorative glass

ionomer cement can result in values for some prop-

erties that are not far from those re"uired for luting

cements, the re"uirements of )5 specifications for

acid erosion could not be met.

204 Vi*ian N. +a,a Sio '. o,n "icado L. (acc,i


ACKNOWLEDGEMENTS

inanced within 4roFect 330, 4roFect 311 and with a scholar-

ship granted to the first author by the Gniversity of ?uenos Aires,

Argentina.

The authors would like to thank entsply Argentina and espe-

cially $r. >aHl >ipoll !Country $anager# for the materials and

their profiles used in this paper, r. elia Takara for her sup-

port in carrying out acid erosion tests, r. AnalIa $os"uera for

her assistance with some tests and $r. Javier aig for his sup-

port with the tests done in this study.

CORRESPONDENCE

r. :ivian '. Kahra

epartment of ental $aterials, 5chool of entistry

$.T. de Alvear %1(%

!C11%%AAosenstiel 5, Mand $, Crispin ?J. ental luting agents6 A

review of the current literature. J 4rosthet ent 100ENE36

%E3-&31.

%. assell >, ?arker , 5teele J;. Crowns and other etra-

coronal restorations6 try-in and cementation of crowns. ?r

ent J %33%N 10&61/-%3, %&-%E.&. ?ehr $, >osentritt $, Moher . Crown behavior during cementation. >eview. Jent 100%N%361+-1%.

0. Tan O, )bbetson >. The effect of cement volume on crown

seating. )nt J 4rosthodont 100N06((+-(+1.

13. $cOen2ie $A, Minden >, 'icholson J. The physical

properties of conventional and resin-modified glass ionomer

dental cements stored in saliva, proprietary acid beverages,

saline and water. ?iomaterials. %33& ctN%(!%%#6(3&-(30.

11. )nternational rgani2ation of 5tandardi2ation. ental-

ater-?ased Cements )5 'o. 001/-16%33/N1-%%.

ACTA-2-2011-PELICULAS:2-2011 12/10/2011 08:40 p.m. Pgina 204

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1.POWDER-CAIR RASIO DAN SIFAT DUA restoratif.doc