Ketac Molar® for ARTmultimedia.3m.com/mws/media/219223O/ketac-molar-for-art-product... · Clinical Research 12/99 2 2. Introduction 2.1 Atraumatic Restorative Treatment The ART technique

Product Dossier

1Clinical Research 6/97

Ketac Molar® for ART

Clinical Research 12/99

Contents

1. Preface.................................................................................... 1

2. Introduction............................................................................ 2

2.1 Atraumatic Restorative Treatment........................................ 22.2 Clinical procedure with the ART technique.......................... 32.3 History of glass ionomers ..................................................... 32.4 Motivation............................................................................... 52.5 Indications.............................................................................. 5

3. Chemical Background......................................................... 6

3.1 General overview................................................................... 63.2 Chemical background ........................................................... 6

4. Product Composition........................................................... 9

4.1 Presentation........................................................................... 94.2 Constituents ......................................................................... 10

5. Test Results ......................................................................... 10

5.1 Material properties............................................................... 105.2 Physico-technical data ........................................................ 115.3 Abrasion tests...................................................................... 135.4 Adhesion tests ..................................................................... 155.5 Marginal behaviour............................................................... 165.6 Fluoride release................................................................... 17

6. In vivo studies on KETAC MOLAR for ART ................... 18

6.1 Multi-centre study in China: ................................................. 186.2 Clinical study in South Africa............................................... 216.3 Clinical study in Peking........................................................ 22

7. Conclusion........................................................................... 22

8. Literature .............................................................................. 23

8.1 Clinical studies with KETAC MOLAR for the ART technique ..................................................................... 238.2 Further literature................................................................... 24

Clinical Research 12/99 1

1. Preface

Espe Dental AG played a major role in developing glass ionomers. Pioneering

inventions such as KETAC-SILVER, a glass ionomer cement reinforced with

sintered particles of silver (McLean, Gasser) were developed by Espe Dental AG

through to market launch in collaboration with well-known universities.

The glass ionomers developed in the 1960s and 70s have been successfully

used in dentistry for about two decades now. This class of material is

characterised by easy handling and self-adhesion, even to untreated dentine.

Glass ionomers possess a translucency similar to that of ceramic materials. Its

biocompatibility is excellent. It is particularly suitable for conservative dentistry but

it is also very successfully used for the cementation of indirect restorations.

Quite recently so-called heavy-bodied, "packable" glass ionomer cements were

developed which are especially indicated as restorative materials for molars and

premolars. One of the best known products in this class of material is KETAC

MOLAR. The mechanical properties, which are better than those of conventional

glass ionomer cements, and its packable consistency make KETAC MOLAR

ideal as a restorative material for primary tooth restorations and in the non-

occluded field for cavity class I restorations. Other fields of indication are semi-

permanent class II restorations and cavity class V restorations.

Since the middle of the 1990s this type of glass ionomer has been increasingly

used for the so-called ART technique (Atraumatic Restorative Treatment). Clinical

studies on this type of therapy testify to the fact that KETAC MOLAR produces

excellent results over a period of at least three years.


2. Introduction

2.1 Atraumatic Restorative Treatment

The ART technique is a method of treatment with the aid of which caries can be

treated at an early stage. The aim of ART is to minimise loss of teeth caused by

caries. Only hand instruments are used. The ART technique is applied without the

need for electricity and without any other elaborate equipment so it can be used

anywhere. The method of treatment was presented by the World Health

Organization (WHO) for the first time in 1994. Areas of application are particularly

countries where it is not possible to ensure that the population has a general

supply of electricity and modern dental equipment is not available everywhere.

However, the ART technique also offers plenty of scope for use in more

developed countries, e.g. in treating the first primary teeth when they appear in

infants. Glass ionomers such as KETAC MOLAR FOR ART are ideal for use as

an ART restorative material on account of their excellent mechanical properties.

No other class of material is characterised by less sensitivity to technique or a

higher level of biocompatibility.

The ART technique already constitutes a form of therapy which has been

scientifically investigated in great detail. Clinical studies in Thailand, Zimbabwe

and China have demonstrated that particularly in the deciduous teeth excellent

results are achieved. In these studies, even after a wearing period of 3 years

retention rates of 90% can be observed in class I cavities.

Apart from the clinical success rates, patient satisfaction constitutes a further

elementary component contributing to the long-term success of the ART

technique. In projects conducted in Zimbabwe and Ghana the acceptance of this

type of therapy was surveyed among the children treated. It became evident that

between 80% and 90% were satisfied both with the treatment and the restoration.

As many as 96% of the patients said they were not afraid of undergoing further

treatment. This constitutes the basis for a long-term improvement in dental health.


2.2 Clinical procedure with the ART technique

For the ART technique only a small number of dental instruments are necessary:

Hand excavator to remove the caries

Mirror for checking purposes

Rubber gloves for the "press finger" technique

Cotton swab for removing Ketac Conditioner

Plastic spatula for mixing Ketac Molar for ART

Rotating instruments, water and electricity are not required but, if they are

available, they can be used at any time. Children to be treated can, for example,

be examined on a table or on their parents' lap. On account of the highly

conservative removal of caries with a hand instrument the use of local

anaesthetics is unnecessary in most cases. When the caries has been removed,

the cavity is conditioned with KETAC MOLAR FOR ART liquid. The conditioning

liquid is applied inside the cavity with a cotton swab and removed again after 10

seconds. Then the cavity is filled with the mixed KETAC MOLAR FOR ART. With

the so-called "press finger" technique KETAC MOLAR FOR ART is pressed into

the cavity. The final modelling of the restoration is performed with a hand

instrument.

2.3 History of glass ionomers

The glass ionomers developed by Wilson and Kent in 1969 have become an

integral part of every dental surgery. Over the years the glass ionomers have

been repeatedly modified and enhanced in order to meet the increasing

requirements expected of this class of material.

Scientific research into glass ionomers pursued two objectives: on the one hand,

the aim was to develop an aesthetically attractive material for anterior teeth

restorations. The other aim was to improve the material properties in order to

expand the fields of application to include anterior teeth. KETAC MOLAR FOR

ART constitutes the logical enhancement of the proven ESPE glass ionomers.



KETAC MOLAR FOR ART is a conventional, metal-free glass ionomer which was

specially developed as a restorative material for molars and premolars. The

improved mechanical properties and the packable consistency were achieved

with an optimised size of glass particles.

2.4 Motivation

As already mentioned heavy-bodied glass ionomers constitute an extremely

promising class of material.

Numerous scientific studies indicate that the strength of heavy-bodied glass

ionomers in comparison with conventional glass ionomers is in some cases

much greater. Particularly the resistance of the heavy-bodied glass ionomers to

abrasion has been increased.

Improved polishability and radiopacity were further aspects which were taken into

account when developing KETAC MOLAR FOR ART.

2.5 Indications

After many years of clinical application of KETAC MOLAR, including applications

as a restorative material in the ART technique, use of the material can be

recommended for the following indications:

• core build-ups

• class I restorations

• semi-permanent class II restorations

• primary tooth restorations


3. Chemical Background

3.1 General overview

Heavy-bodied glass ionomers are obtained not only by simply mixing glass

powder and a polycarbonic acid. As with conventional glass ionomers, the curing

takes place between the polycarbonic acids in the fluid and the reactive fluoro-

calcium-aluminium-silicate-glass of the glass powder. In contrast with

conventional glass ionomers these cements are characterised by a much higher

abrasive stability.

3.2 Chemical background

The curing of glass ionomers is a complex sequence of chemical reactions in

which water plays a major role. Whilst in the first curing phase the presence of

water as a solvent is crucial for starting the reaction between the powder and

polycarbonic acid, the glass ionomers are extremely sensitive to the ingress of

water in the subsequent curing phase. But excess drying should also be avoided.

The chemical processes in curing may be divided into different stages.

1) Decomposition of the glass structure:

A major requirement for the types of glass used is their solubility in acids. Whilst

cross-linked silicates are attacked by virtually no acid, calcium-aluminium-silicate

types of glass even react with a relatively weak polycarbonic acid. The reason for

this is the aluminium component in the glass. Aluminium is integrated into the

cross-linked silicate and ensures that the aluminosilicate acquires a formally

negative charge. As a result the glass turns alkaline and can therefore be attacked

by inorganic acids, but also by organic ones. These negative charges are

compensated for in the glass powder with alkaline ions or alkaline earth ions (see

Fig. 1).


Fig. 1: Structure of an aluminosilicate(Illustration: A. D. Wilson, J. W. McLean "Glass Ionomers", published by Quintessenz,1988, p. 26)

In the first step the calcium and sodium ions are replaced by protons. Then, in a

second step, all the aluminium-oxygen bonds are broken and orthosilicic acid

forms.

Acid attac

Glass structurewithout acid attack

First stage Second stage

[SiO4] Tetrahedron [AlO4]- Tetrahedron Si(OH)4 Orthosilicic acid


2) Curing

Fig. 2: Formation of the silica gel at the surface of the glass(Ill. A. D. Wilson, J. W McLean, "Glass Ionomers", published by Quintessenz, 1988, p. 45)

Acid attack takes place at the surface of the glass particles. It is a heterogeneous

reaction between a solid and a liquid. The resulting silicic acid reacts

spontaneously with other molecules of silicic acid causing polycondensation to

form a silica gel.

The ions which were originally firmly integrated into the glass are released and

migrate into the aqueous phase of the cement. This effect can be observed, for

example, during the release of fluoride ions from the glass ionomers. The cations

released react with the anions of the polycarbonic acids to form

polycarboxysilates which are insoluble in water.


3) Action of the tartaric acid

To ensure adequate working time, tartaric acid is used as a complexation reagent

for the dissolved metal ions. The complexation during the first setting period

causes metal ions to be temporarily withdrawn from cross-linking with the

polyanions. This reaction is a reversible process. At the subsequent setting stage

the previously complexed metal ions are again available for cross-linking. In this

way the setting process can be optimised for a practical procedure. Working time

is extended and setting time is reduced ("Snap set").

4. Product Composition

Glass ionomers (polyalkenoate cements) consist of the powder/liquid combination

characteristic of dental cements. Conventional glass ionomers use polycarbonic

acids. The powder component includes special reactive types of glass. The

curing mechanism is an acid-base reaction between these types of glass and the

polycarbonic acid from the liquid.

4.1 Presentation

KETAC MOLAR FOR ART is a two-component, chemically curing, glass ionomerbased restorative material. The product is available both as a capsule version(KETAC MOLAR APLICAP) with its user-friendly direct application feature and asthe successful hand-mix version (KETAC MOLAR FOR ART).


4.2 Constituents

The qualitative composition of the two components of KETAC MOLAR FOR ART

is listed in tables 1 and 2.

Table 1: Composition of the powder contained in KETAC MOLAR FOR ART

Ca, La, Al-fluorosilicate glass

Pigments

The mean size of glass particles contained in the powder of KETAC MOLAR FOR

ART is 2.7 µm. The grain size distribution indicates that 90% of all the particles

are smaller than 9 µm and 10% of all the particles are smaller than 1 µm.

Table 2: Composition of the liquid contained in KETAC MOLAR for ART

Polycarbonic acid

Tartaric acid

Water

The liquid is preserved with benzoic acid. The powder/liquid ratio is 2.9:1

5. Test Results

5.1 Material properties

The setting process for glass ionomers already described in the previous chapter

causes materials in this class to cure with virtually no contraction. Therefore there


are only minimal stresses in the material which can lead to marginal gap

formation at the cavity margins. For this reason, when using glass ionomers no

additional complex bonding agents have to be applied as is normally necessary

with polymerisation products. Consequently there is no need for a high strength of

bond to the enamel and dentine, which tends to counteract contraction due to

setting.

Furthermore, glass ionomers have a coefficient of thermal expansion which is

similar to that of the teeth. Additional stress on the adhesive bond between the

restorative material and the hard tooth substance caused by large temperature

differences thus does not arise. These two material properties ensure that an

optimised clinical marginal behaviour of glass ionomers can be achieved without

having to specify high bond strength.

Another important material property of glass ionomers is resistance to abrasion.

When using conventional glass ionomers the abrasion/erosion of the restoration,

particularly in the molars and premolars, is a defect which is frequently observed.

In the oral cavity, glass ionomers are subject to chemical and mechanical

degradation. At the point of contact between the restoration and the tooth the

result is formation of "negative ledges". Consequently, for an aesthetically and

clinically attractive restoration it is not only the above-mentioned properties which

are desirable but also high resistance to abrasion.

5.2 Physico-technical data

5.2.1 Internal tests

The physical properties of KETAC MOLAR for ART are listed in table 3. The

figures are based on specification test procedures issued by the International

Standards Organization (ISO) and the German Institute for Standards (DIN).


KETAC MOLAR is available both as a capsule version (KETAC MOLAR

APLICAP) with its user-friendly direct application feature, and as a tried and tested

hand-mix version (KETAC MOLAR for ART). The physico-technical

characteristics of

KETAC MOLAR APLICAP and KETAC MOLAR for ART are no different from one

another on account of the inaccuracy in measurement. Owing to this analogous

relationship the capsule version results listed in chapter 5 also apply to the hand-

mix version.

Table 3: Mechanical properties of KETAC MOLAR for ART

KETAC MOLAR for ARTKETAC MOLAR

APLICAPStandard

Setting time 3:30 (min:sec) 2:15 (min:sec) ISO 9917

Compressivestrength

210 MPa 230 MPa ISO 9917

Flexural strength 37 MPa 30 MPa ISO 4049

Surface hardness 420 MPa 450 MPa ISO 53456

Radiopacity 250% 270% ISO 4049

5.2.2 External tests at universities

The flexural strength of glass ionomers constitutes an important criterion in

assessing quality. High flexural strength has a major influence on the clinical

success of a restoration. Apart from the ISO method already described above for

measuring 3-point flexural strength, 4-point flexural strength also represents a

valid method for measuring this material property. It is evident that the individual

materials tested differ with regard to the mean flexural strength, considerably in

some cases.


0

2

4

6

8

10

12

14

16

18

20

[MP

a]

Ketac Molar Fuji IX HiDense

Fig. 3: 4-point flexural strength of different heavy-bodied glass ionomer cements andKetac-Fil Plus(unpublished results: Sindel et al., University of Erlangen)

5.3 Abrasion tests

The problem of resistance to the oral environment and of durability is of major

importance for all dental materials. The long-term success of conventional glass

ionomers can be influenced in various ways: by working the glass ionomer

restorative material, protecting the restoration against damaging influences in the

oral cavity which may cause the material to erode, and by adjusting the

mechanical properties of the material. Among the large number of mechanical

properties, resistance to abrasion is an important aspect for ensuring that the

restoration has a long life.


Since conventional glass ionomers can only have inadequate strength relative to

abrasion resistance, endeavours were made during development of KETAC

MOLAR for ART to achieve a considerable improvement in the mechanical

properties by optimising composition. By varying the powder/liquid ratio and the

grain size distribution it was possible to achieve higher levels of strength and keep

the setting behaviour user-friendly at the same time.

The behaviour of KETAC MOLAR (Aplicap) with regard to abrasion and that of the

main rival products was determined by means of a 3-media abrasion procedure

("ACTA method") (Fig. 4). It is evident from the results that for all heavy-bodied

glass ionomer cements, with the exception of Fuji IX, virtually identical abrasion

values can be obtained.

0

5

10

15

20

25

30

35

40

45

50

[µm

]

KetacMolar

Fuji IX HiDense IonofilMolar

Fig. 4: 3-media abrasion of heavy-bodied glass ionomers(Lohbauer et al., University of Erlangen)


5.4 Adhesion tests

A durable bond between the glass ionomer and the hard tooth substances is

indispensable to ensure the durability of a restoration. Good marginal adaptation

prevents leakages, secondary caries and pulpal irritation. By contrast with the

acid etching technique for composites the adhesion of glass ionomers to the hard

tooth substances is of a purely chemical nature. Micromechanical retention

plays no role whatsoever in the adhesion of glass ionomers. With the proposed

adhesive mechanism, complexation of the carboxylate groups from the glass

ionomer with the calcium ions from the hydroxyl apatite of enamel and dentine is

crucial. Adhesion to the enamel tends to be greater than adhesion to the dentine.

The reason for this is that approx. 98% of enamel and only 70% of dentine is

made of hydroxyl apatite. In the case of dentine, therefore, a glass ionomer chiefly

adheres to the apatite components. There is only minimal or no adhesion

whatsoever to the collagen.

0

1

2

3

4

5

6

[MP

a]

Ketac Molar Fuji IX

Fig. 5: Shear bond strength of KETAC MOLAR to the enamel(K.-H. Friedl et al., University of Regensburg)


5.5 Marginal behaviour

As already mentioned, good marginal behaviour is a crucial criterion in assessing

the quality of a restorative material.

In an in vitro investigation at the Okayama University Dental School the marginal

integrity of glass ionomer restorations was examined for KETAC MOLAR and Fuji

IX. As soon as the restoration had been placed and again after one day of

exposure to water, light microscopy was performed to investigate how wide the

gap which had formed was at the widest point. Fig. 6 shows that virtually identical

values can be obtained for both products.

0123456789

10

[µm

]

Ketac Molar Fuji IX

Sofort

1. Tag

Fig. 6: Marginal behaviour of KETAC MOLAR(M. Irie, Okayama University)


5.6 Fluoride release

Glass ionomers are generally characterised by a high release of fluoride. The

clinical relevance of this fluoride release has been discussed controversially for

many years now. Indications that glass ionomers have a cariostatic effect may,

inter alia, be found in a study by Mejàre and Mjör, in which glass ionomers were

used as fissure sealants. In none of the cases investigated was secondary caries

found, although over a total observation period of 5 years a loss rate of 61% in 6-

12 months and a loss rate of 84% in 30-36 months was established for glass

ionomer sealants. By comparison, the rate of caries in the resin sealant control

group was 5% over the same period.

A three-year study which was performed by Karlzén-Reuterving et al. resulted in a

similar picture. Whilst the retention of a resin-reinforced glass ionomer cement

was only 27.8% after three years, caries occurred in only 1.4% of the cases. By

comparison, the rate of caries for a resin sealant was 4.2%, although 79.2% of

the sealants were still present. The authors of that study maintain that the positive

effect of the glass ionomers was due to a cariostatic effect of glass ionomer

materials. Numerous other authors suggest a connection between the provable

fluoride release of glass ionomer cements and their action with regard to caries

prevention.


0

0,5

1

1,5

2

2,5

3

3,5

4

4,5

1. W

oche

2. W

oche

3. W

oche

4. W

oche

5. W

oche

6. W

oche

7. W

oche

8. W

oche

[pp

m]

Fig. 7: Fluoride release of KETAC MOLAR(internal measurements, ESPE Dental AG)

Figure 7 shows that KETAC MOLAR continuously releases fluoride ions over aperiod of two months.

6. In vivo studies on KETAC MOLAR for ART

Over the last few years many clinical studies have been performed for KETAC

MOLAR for ART. Below there is a summary of some of the results.

6.1 Multi-centre study in China:

In a long-term study conducted by Dr. Chris Holmgren and Dr. Edward Lo on

deciduous teeth, KETAC MOLAR for ART was used both in small and large class

I cavities and as a fissure sealant. All in all, 294 ART restorations and 191 fissure

sealants were placed in 140 schoolchildren at 4 different schools. The

restorations were checked once a year. For the 3-year investigation the

restorations were checked by an independent examiner in accordance with

USPHS criteria. The USPHS criteria are internationally recognised clinical quality

criteria, according to which restorations are normally assessed in clinical studies.


After three years 92% of all the small class I restoration and 77% of all the large

class I restorations were classified as clinically successful.

0

20

40

60

80

100

Bas

elin

e

1 Y

ea

r

2 Y

ea

rs

3 Y

ea

rs

Class I(small)

Class I(large)

Fig. 8: Retention rates for various ART restorations(C. Holmgren et al.)

Fig. 9: Baseline 1 year

Fig. 10: 2 years 3 years


Over the entire period of observation 72% of the fissure sealants were partially or

entirely present. In only 2% of sealed teeth had secondary caries occurred during

the period of observation.

Fig. 11: Baseline 3 years

0%

20%

40%

60%

80%

100%

3 M

onat

e

1 Ja

hr

2 Ja

hre

3 Ja

hre

Sek

undä

r-K

arie

s (3

Jah

re)

Loss

Intact/partial loss

Fig. 12: Retention of fissure sealants(C. Holmgren et al.)

The study demonstrated that KETAC MOLAR for ART very effectively helps in

treating existing cases of caries and reducing the occurrence of caries when

used as a sealant. Furthermore, the acceptance of ART therapy by children being

treated is very high. A survey conducted during the study showed that 92% of the

children were no longer afraid of a continuation of ART treatment.


6.2 Clinical study in South Africa

In a controlled "Split Mouth" design study with KETAC MOLAR for ART on

deciduous teeth, which was performed by Mickenautsch et al in South Africa, Fuji

IX served as the control group. The schoolchildren participating had no access to

dental treatment. In total, 1,325 children with an average age of 10.5 years were

examined at 16 primary schools. 63.8% of the children had no caries and the

mean DMFT value (index resulting from the total of carious, missing and restored

teeth) was 1.08. A total of 163 cavities were treated with KETAC MOLAR for ART

and Fuji IX. After one year 108 restorations were subjected to a check-up. Over

the observation period of 12 months the proportion of successful KETAC MOLAR

for ART restorations was 94%. For the Fuji IX control group the proportion of intact

restorations was 93.1%.

By comparison with previous data obtained by the team, which was recorded at a

time when the population observed still had no access to the ART technique, a

significant reduction in tooth extractions was observed both for permanent teeth

and deciduous teeth.

-40

-35

-30

-25

-20

-15

-10

-5

0

[%]

Molars andpremolars(deciduous)

Molars andpremolars(Permanent)

Fig.: 13: Reduction in the number of extractions after using the ART

technique (comparative data: 1.2.95 - 31.1.96)

In the authors' view the ART technique constitutes an attractive form of therapy for

treating caries defects in the population described. No statistically significant

differences were observed between KETAC MOLAR for ART and the control

group.


6.3 Clinical study in Peking

In a clinical study conducted by Smales, Yip et al. the clinical successes of

KETAC MOLAR for ART restorations were compared with those of Fuji IX after an

observation period of 12 months. The study also compared the ART technique

and the conventional method of treatment with rotary instruments. A total of 149

class I restorations were placed for baseline examination. After 12 months 98

restorations were checked. In the case of KETAC MOLAR for ART one

restoration and one fissure sealant were reported to have been lost over the

observation period. Despite the loss of the sealant no formation of caries was

found on the tooth involved. KETAC MOLAR for ART and Fuji IX produced virtually

identical results with regard to clinical success.

7. Conclusion

The glass ionomers developed in the 1960s and 1970s cover a wide field of

applications. Owing to the low abrasion resistance of conventional glass

ionomers heavy-bodied glass ionomers were developed. This class of material

manifests a number of positive properties compared with conventional glass

ionomers, which make it ideal for a large number of clinical applications, including

the ART technique.

The ART technique is a method with which caries can be treated at an early

stage. The aim of ART is to minimise tooth loss caused by caries. In many

laboratory investigations and clinical studies KETAC MOLAR for ART was found

to produce excellent results particularly when used with an ART technique.

Especially when used as a restorative material for class I cavities or as a fissure

sealant, KETAC MOLAR for ART has proved successful all over the world. A

study

in South Africa demonstrated that when KETAC MOLAR for ART was used the

chief aim of the ART technique, namely to minimise tooth loss, was achieved

convincingly. Undesirable tooth loss was reduced by over 35% in that study.


8. Literature

8.1 Clinical studies with KETAC MOLAR for the ARTtechnique

E. C. M. Lo, C.J. Holmgren"Eighteen-month evaluation of ART fillings placed in Chinese preschool children"J. Dent. Res. (IADR Abstract # 2101), 1999.

S. Mickenautsch, M.J. Rudolph, E. O. Ogunbodede"The impact of the ART approach on the treatment profile in a Mobile DentalSystem (MDS) in South Africa"Int. Dent. J. 49, 132-138, 1999.

E.C.M. Lo, C.J. Holmgren, H.C. Wan, D.Y. Hu"Provision of Atraumatic Restorative Treatment (ART) in Western China -one year results"J. Dent. Res. (IADR Abstract # 37), 1998.

W. Gao, D. Peng, R.J. Smales, M.S. Gale„Clinical trial of ART technique restorative Gl cements: initial findings"J. Dent. Res. (IADR Abstract # 40), 1998.

8.2 General literature on Ketac Molar

U. Lohbauer, M. Pelka, R. Frankenberger, N. Krämer"Influence of Mixing Procedures on Wear Resistance of Glass IonomerCements"J. Dent. Res. (IADR Abstract # 988), 1999.

R. Frankenberger, N. Krämer, A. Graf, A. Petschelt"Zyklische Ermüdung von Glasionomerzementen und Kompomeren"Dtsch. Zahnärztl. Z. 54, 269-271, 1999.

M. Pelka, J. Sindel, A. Petschelt"Lapping Abrasion Behavior of Condensable Glass-ionomers"J. Dent. Res. (IADR Abstract # 2739), 1999.

M. Irie, T. Yamada, H. Nakai"Marginal Adaptation of High-viscosity Glass lonomers in Enamel Margins"J. Dent. Res. (IADR Abstract # 1452), 1998.

C.C. France, M.R. Towler, R.W. Billington"Correlation between erosion and stress relaxation in maturing glass-ionomers"J. Dent. Res. (IADR Abstract # 463), 1998.


M.C.P. Nunes, D.F.G. Cefaly, L. Tenuta, J.R.P. Lauris, M.F.L. Navarro"Compressive and Diametral Tensile Strength of Two Restorative Glasslonomer Cements"J.J. Dent. Res. (IADR Abstract # 458), 1998.

K.-P. Stefan"Early solubility of glass ionomer cements"J. Dent. Res. (IADR Abstract # 454), 1998.

J. Ellacuria, R. Triana, N. Minguez, E. Guinea, F. Soler, F. Garcia-Godoy"Effects of Aging Time on Microhardness of Glass Ionomer Cements"J. Dent. Res. (IADR Abstract # 459), 1998.

T.F. Watson, M. Naasan, M. Sherriff"Maturation of Glass Ionomer Cements and Shear Bond Strength (SBS)J. Dent. Res. (IADR Abstract # 384) 1998.

A. Peutzfeldt, F. Garcia-Godoy, E. Asmussen"Surface hardness and wear of glass ionomers and compomers"Am. J. Dent. 10. 15-17, 1997.

K.-H. Friedl, G. Schmalz, K.-A. Hiller, A. Gottlieb"Bond Strength of resin modified glass ionomer cements and compomers"J. Dent. Res. (IADR Abstract # 2400), 1997.

A. Graf, J. Sindel, N. Krämer, A. Petschelt"Wear and Cyclic Fatigue of new Glass Ionomer Cements"J. Dent. Res. (IADR Abstract # 2427), 1997.

R. Frankenberger, J. Sindel, N. Krämer"Stopfbare Glasionomerzemente - eine neue Amalgamalternative imMilchgebiß?"Quintessenz 47, 1535-1549, 1996.

8.2 Further literature

l. Mejàre, I.A. Mjör"Glass ionomer and resin-based fissure sealants: a clinical study"Scand. J. Dent. Res. 98, 345-350, 1990.

G. KarIzén-Reuterving, J.W.V. van Dijken"A three-year follow-up of glass (ionomer cement and resin fissure sealants"Journal of dentistry for children, 108-110, 1995.

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