Dental Cement Physical and Mechanical Properties by In Vivo

Approach

Prihartini Widiyanti

1,2

, Siswanto

and Idha Sa’Ada

Biomedical Engineering Study Program, Department of Physics, Faculty of Science and Technology, Universitas

Airlangga, Indonesia

Physics Study Program, Department of Physics, Faculty of Science and Technology, Universitas Airlangga, Indonesia

Keywords: Dental Cements, Tensile Strength, Compressive Strength, Morphological Feature, In Vivo Approach.

Abstract: The current production technology of dental cement material is growing rapidly compared to 50 years ago.

Cement as dental restoration material must be elastic and have a low conductivity property. There are four

kinds of dental cement commonly used in dentistry, namely zinc phosphate cement, polycarboxylate

cement, glass ionomer cement, and zinc oxide and eugenol cement. There is no study about physical and

mechanical properties based on in-vivo condition. This study aims to know the physical and mechanical

properties of dental cement, by the in-vivo approach and using rabbit as an experimental object. Dental

cements used in this research were zinc phosphate cement (ZPC), polycarboxylate cement (PC), glass

ionomer cement (GIC), and zinc oxide and eugenol cement (ZOEC). The method of this study was the

preparation of tools, materials and experimental animals. We used six male - 5 months in age - rabbits.

Before being treated (fill-teeth material insertion), the rabbits were anesthetized by an anaesthetist from the

Animal Hospital, Faculty of Veterinary Medicine, Universitas Airlangga. Then the rabbit teeth were drilled

and formed to become box cavity. Information which can be obtained from this in-vivo experiment is its

physical and mechanical properties i.e. compressive strength, tensile strength, and microstructure of dental

cement. Based on the physical and mechanical characterization value, the best compressive strength was

101.888 MPa and refers to zinc phosphate cement and the best tensile strength value was glass ionomer

cement with 6.555 MPa. The morphological features, mainly surface structure of dental cement, showed

less well sealed for zinc phosphate cement, strongly bonded with teeth for polycarboxylate cement, there

were lumps of unreacted powder particles for glass ionomer cement and there was a very hard lump formed

for zinc oxide and eugenol cement.

1 INTRODUCTION

The technology of dental cement nowadays is

emerging compared to 50 years ago. This condition

facilitates the dentists to have more choice to restore

the broken teeth or even the loose teeth. One of the

dental cement alternatives is by using polymer.

Some scientists have developed the polymer-based

material to be close to the characteristics and

appearance of the natural teeth (Wagh, 2016;

Manappallil JJ, 2016)

The polymer is a long chain molecule consisting

of several repetitions of units (Combe, 2013). Most

of the polymer was used in the industry or medical

area. One example of polymer used in the medical

area is teeth filling material (dental cement). Cement

as a teeth filler should be elastic (low strength

materials). This cement could be synthesized by

mixing the powder material with some liquid. The

cement composition varies in chemical composition,

characteristics, or the usage. This material also has

low conductivity compared to the metal filling

material.

Four types of dental cement are normally used in

dentistry, zinc-phosphate cement, polycarboxylate

cement, glass ionomer cement, and zinc oxide and

eugenol cement (Noort, 2002).

There was a study that synthesized the zinc

phosphate dental cement zinc oxide and phosphate

acid (Wagh AS, 2016). This study results showed

that the mechanical properties on the zinc phosphate

dental cement increased with the increase of

powder-liquid ratio until their mass was the same.

But, it would decrease if the liquid ratio increased in

the composition ratio. The best composition ratio in

274

Widiyanti, P., Siswanto, . and Sa’Ada, I.

Dental Cement Physical and Mechanical Properties by In Vivo Approach.

DOI: 10.5220/0007541302740280

In Proceedings of the 2nd International Conference Postgraduate School (ICPS 2018), pages 274-280

ISBN: 978-989-758-348-3

the zinc phosphate dental cement was at 60:40

respective to powder and liquid.

The study of the addition of polystyrene as an

additive substance in the dental cement based on

zinc oxide eugenol has been performed. Polystyrene

is a linear polymer that has thermoplastic property.

This material would be melted at a temperature

around 95°C and become viscous solution at 120-

180°C and become liquid above 250°C, then

degraded above 320-350°C. This study concluded

that the addition of polystyrene to the eugenol, as

much as 10%, could give the best mechanical

properties. Fourier Transform Infrared (FT-IR)

spectrophotometer is a device to make a chemical-

physical identification, especially in the qualitative

analysis on the functional group of organic or an-

organic materials based on the absorbance towards

infrared. FTIR test showed that the mixing of

polystyrene and eugenol is a simple mixture.

From that study, there was a lack in the physical

and mechanical properties testing which was no in-

vivo test using living organism yet. This study

would use the rabbit as a living organism for an in-

vivo test. The teeth of the rabbit would be recessed

as in the class III caries. This type of caries usually

occurs on the anterior teeth and could occur on the

medial or distal surface of the incisor or canine.

From the in-vivo test, the information about the

physical and mechanical properties could be

obtained comprising compressive strength, tensile

strength, and microstructure from several types of

dental cements.

2 MATERIALS AND METHODS

2.1 Materials

The first step of this study was the preparation of the

tools to drill and patch the teeth. They were round

bur, fissure bur and tapered bur for class III cavity

preparation, cement spatula for mixing and taking

the dental cement materials, straight probe for

detecting the cavity, dental tweezers for helping to

take the bur eye, debris and cotton, plastic filling

instrument for inserting the dental cement materials

in the cavity, the glass plate and mixing paper for

mixing the materials, and cotton roll for blocking the

saliva.

The materials for dental patching were zinc

phosphate cement, polycarboxylate cement, glass

ionomer cement, zinc oxide and eugenol cement.

Those four types of dental cements were a package

of powder and liquid that could be obtained in the

market.

The preparation of the animal trial started with

six male rabbits with age of five months. Before the

treatment, the rabbit was anesthetized first to know

their condition. To ease the preparation of the cavity

on the rabbit’s teeth, the rabbits were stunned. The

anesthesia was performed by the vet of Universitas

Airlangga as shown in Table 1.

Table 1: Anesthesia of the animal

F1 F2 F3 F4 F5 F6

Weight (kg) 1.8 2 1.5 1.9 1.6 1.7

Xylazine (ml) 0.5 0.5 0.4 0.5 0.4 0.5

Antrophine

(ml)

0.4 0.4 0.3 0.4 0.3 0.4

Ketamine (ml) 0.9 1 0.8 0.9 0.8 0.9

2.2 Testing Sample Preparation

After the preparation of the tools and materials, the

animal trial sample was prepared. Two incisors of

the rabbit were drilled as shown in Figure 1. The

preparation of class III cavity used round bur, fissure

bur and tapered bur. The preparation was only at the

dentin. After the preparation, the cavity was cleaned

with alcohol-dipped cotton. The caries was detected

by using tweezers.

Figure 1: Class III Cavity based on the position of Caries

After the cavity was dry and clean, the patching

process was performed. The patching area was

isolated by cotton roll to prevent the saliva from

inserting the cavity. The patching materials were

prepared in the glass plate based on the usual

procedure and stirred with cement spatula. Specific

to glass ionomer cement, the patching material was

stirred on the mixing paper with plastic cement

Dental Cement Physical and Mechanical Properties by In Vivo Approach

275

spatula. The patching materials were then inserted in

the cavity by using the plastic filling instrument.

After one or two minutes, the patching was pressed

with amalgam stopper and formed.

On the Rabbit I, the cavity was patched by

using zinc phosphate cement. On the Rabbit II, the

cavity was patched by using polycarboxylate

cement. On the Rabbit III, the cavity was patched by

using glass ionomer cement and on the Rabbit IV,

the cavity was patched by using zinc oxide and

eugenol cement. On the Rabbit V, the right cavity

was patched by using zinc phosphate cement and the

left cavity was patched by using polycarboxylate

cement. On the Rabbit VI, the right cavity was

patched by using glass ionomer cement and the left

cavity was patched by using zinc oxide and eugenol

cement. The total of the overall samples were 12

pieces as shown in Table 2.

Table 2: In-Vivo Test Sample

No. Sample

Amount

(tail)

Dental Cement

1. A 3 zinc phosphate

cement

2. B 3 polycarboxylate

cement

3. C 3 glass ionomer

cement

4. D 3 zinc oxide and

eugenol cement

The categorization of A, B, C, D was based

on the type of cements applied in the tooth cavity

After the patching process, the sample caring

was performed for 21 days to observe the strength of

the patch after patched to the teeth through in-vivo

test. After that, the teeth were alienated using incisor

teeth alienating pliers and characterized.

2.3 The Sample Characterization

The aim of this characterization was to know the

compressive strength, tensile strength and

microstructure of the dental cement.

2.3.1 Compressive Strength

Compressive strength testing was using Autograph.

The load used in this test was 100 kN. From this test,

the compressive strength given to the sample until it

breaks of fractures was obtained. By using equation

(1), the compressive strength could be determined.

(1)

τ is the compressive strength (Pa),

the load on

the sample (N), and

is area (m

2.3.2 Tensile Strength

For knowing the stickiness of the dental cement,

tensile strength testing was used by giving a tensile

load directly to the sample. To ensure the sample

held firmly, the tip of the sample was made bigger

than the middle part of the sample. The tensile

strength measurement was using Autograph. By

using equation (2), the tensile strength was

determined.

TS =

(2)

TS is the tensile strength (Pa), F is the load

(N), and A is the area (m

2.3.3 Microstructure

To know the microstructure, a Scanning Electron

Microscope (SEM) was used. The sample was

prepared first by coating with a specific material

(gold) in the stub from metal with a diameter of 9

mm. The sample was then inserted into the specimen

chamber and illuminated with the electron beam (20

kV). The reflected electron was detected by the

scintillator detector amplified by an electrical circuit

that could produce a figure from a Cathode Ray

Tube (CRT). The capturing process was performed

after choosing a specific part of the sample with the

correct magnification so that a good and clear image

was obtained. To print the film of the capturing

result, a vacuum evaporator JEOL JEE-4X was used.

3 RESULT

This study performed an in-vivo test by using a

living organism. The in-vivo test gained the

information of the physical and mechanical

properties, such as compressive strength, tensile

strength, and microstructure from zinc phosphate

cement, polycarboxylate cement, glass ionomer

cement), and zinc oxide and eugenol cement.

ICPS 2018 - 2nd International Conference Postgraduate School

276

3.1 Sample Testing Result

This study was performed experimentally by

measuring the mechanical properties, which were

compressive strength and tensile strength. The

sample characterization result is shown in Table 3.

Table 3: The Result of Sample Characterization

No. Sample

Type

Compressive

Strength (MPa)

Tensile

Strength

(MPa)

1. A 101.888 5.777

2. B 56.555 6.111

3. C 70.777 6.555

4. D 46.111 3.111

Description :

A = zinc phosphate cement

B = polycarboxylate cement

C = glass ionomer cement

D = zinc oxide and eugenol cement

From the result of sample characterization, there

was a relation between the type of dental cement and

their mechanical properties. The graphs of

compressive strength and tensile strength are shown

in Figures 2 and 3.

100

120

ABCD

C o m press ive St reng th

(MPa)

Type of Dental Cement

Graph of Compressive Strength Dental

Cement

Figure 2: The Compressive Strength of Several Dental

Cements

Figure 3: The Tensile Strength of Several

Dental Cements

The microstructure of the dental cement could

be observed from the result of SEM. The

microstructure of the dental cement is shown in

Figure 4.

Dental Cement Physical and Mechanical Properties by In Vivo Approach

277

Figure 4: (a) The microstructure of zinc phosphate cement.

(b) The microstructure of polycarboxylate cement. (c) The

microstructure of glass ionomer cement. (d) The

microstructure of zinc oxide and eugenol cement

4 DISCUSSION

The results on the mechanical properties of the

dental cement show that the best compressive

strength was the zinc phosphate cement at 101.888

MPa and the best tensile strength was glass ionomer

at 6.555 MPa. If manipulated correctly, the zinc

phosphate cement could have the compressive

strength of 104 MPa and tensile strength of 5.5 MPa

(Anusavice, 2003).

The compressive strength and tensile strength

were various based on the ratio of the powder and

liquid. The increase in the strength was obtained by

adding more powder than was recommended and it

was obvious compared to the decrease of the

strength caused by the decrease of the powder in the

mixture. The decrease of the ratio of powder and

liquid would produce a weak cement. The lack or

increase of water content from the liquid would

decrease the tensile strength and compressive

strength of the cement. Like zinc phosphate cement,

glass ionomer cement would be easy to break when

hardening. After that, the recess of the cement could

be thrown away by gouging or breaking the cement

away from the restoration side. This cement is

sensitive to water contamination in the hardening

process. Thus, the restoration side should be coated

to protect the cement from early contact with a

liquid.

The compressive strength from polycarboxylate

cement was lower than the zinc phosphate cement

but had a slightly higher tensile strength. This

cement was not as brittle as zinc phosphate cement,

so that it was more difficult to eliminate the recess

of the cement after the cement hardened.

The mechanical properties of the zinc oxide and

eugenol cement were lower than the other cements.

This cement was hard to manipulate in the mouth

cavity. The thickness of its layer tended to be higher

and the recess of the hardened cement was hard to

remove.

The difference in compressive strength and

tensile strength was caused by the speed of mixing

between the powder and the liquid, the mixture plate

and the temperature of the mixing tools. The speed

of the mixing between powder and liquid could

affect the hardness of the dental cement because the

powder that was mixed with the liquid gradually

with a small amount would increase the working

time and hardness so that it could decrease the heat

produced and allow more powder to be added to the

mixture.

The mixture plate and the temperature of the

mixing tools could also affect the mechanical

properties of the dental cement. The high

temperature on the mixing tools could increase the

hardening reaction from the dental cement. On the

other hand, if the temperature of the mixing tools

was low, then the hardening reaction of the dental

cement could be longer so that the matrix formation

could be slowed down. Besides that, what needs to

be taken into account is the technique of mixing the

powder and liquid. The inappropriate mixing could

cause a crack in the dental cement so that it would

complicate the mechanical properties measurement.

The microstructure of the zinc phosphate cement

in Figure 4(a) showed that the dental cement and the

teeth were not stuck together. When the powder was

mixed with the liquid, the phosphoric acid had

contact with the particle surface and released zinc

ions to the liquid. The aluminium, which has been

bonded to the phosphoric acid, reacts to the zinc and

produces zinc gel as aluminophosphate on the

surface of the residual particles. This hardened

cement is the main structure and consisted of

unreacted zinc oxide particles, coated with a solid

matrix that has not been formed from the zinc

aluminophosphate. Because water affects the acid-

ICPS 2018 - 2nd International Conference Postgraduate School

278

base reaction, the composition of the liquid should

be maintained to ensure a consistent reaction. The

change in composition and reaction speed could

occur due to the evaporation of the water. So, the

change in composition could affect the reaction.

The microstructure of the polycarboxylate

cement in Figure 4(b) showed that the cement was

bonded tightly to the tooth structure. The hardening

reaction of this cement involved the dissolution of

the particle surface by the acid that released the zinc,

magnesium, and tin ions and merged to the polymer

chain though carboxyl group. These ions react to the

carboxyl group and polyacid chain near them and

form a salt with crosslink while the cement was

hardening. The hardenend cement consisted of non-

uniform matrix gel with a spread of unreacted

particles inside. The microstructure image was

similar to the zinc phosphate cement.

The microstructure of the glass ionomer cement

in Figure 4(c) showed that there was a lump of

powder particles that did not react. When the powder

and the liquid were mixed to form a paste, the glass

particle surface would be dissolved in the acid. The

calcium, aluminium, sodium, and fluorine ions were

released to the watery media. The polyacrylic acid

chain would crosslink with the calcium ions and

form a solid mass. For the next 24 hours, a new

phase was formed in which aluminium ions bond in

the cement mixture and form a brittle cement.

Sodium and fluorine ions did not have a part in the

crosslinking of the cement. Some of the sodium ions

could replace hydrogen ions from the carboxylic

group, and the rest would join the fluorine to form

natrium fluoride that spread evenly in the hardened

cement. Along the hardening process, the

crosslinking phase was also hydrated by the same

water as the medium. The parts that did not react

with the glass particles would be coated by the silica

gels that have been formed during the cation release

from the particles surface. Thus, the hardened

cement consisted of lumps of powder particles that

have not reacted and been surrounded by the silica

gels in the amorphous matrix of calcium hydrate and

a mixture of aluminium salt.

The microstructure of the zinc oxide and eugenol

cement in Figure 4(d) showed that there was a hard

lump. In the right condition, the reaction between

zinc oxide and eugenol resulted in a hard relative

mass. The hardening mechanism of the zinc oxide

eugenol materials consisted of hydrolysis of zinc

oxide and eugenol to form lumps. Zinc acetic

dihydrate accelerated it, that was more soluble than

zinc hydroxide and could give zinc ions faster. The

high temperature could increase the hardening

speed.

The main property of the dental cement is that it

should last in the solubility and disintegration in the

mouth cavity. The cement had continuous contact

with several types of acid produced by the

microorganism and food processing. Some of them

were carried to the mouth as food and beverages. pH

and temperature in the mouth cavity were always

changing. So, no cement could fulfill all desired

ideal characteristics. A cement system is maybe

suitable for one use compared to the other system.

Every condition must be evaluated based on the

environment and biological and mechanical factors.

5 CONCLUSIONS

Based on the in-vivo test, the physical and

mechanical properties were obtained from four types

of dental cements. The mechanical properties were

determined through compressive strength and tensile

strength. The best compressive strength was shown

by zinc phosphate dental cement at 101.888 MPa

and tensile strength from glass ionomer cement at

6.555 MPa. The dental cement from zinc oxide and

eugenol had the lowest physical properties compared

to the other dental cements.

ACKNOWLEDGEMENTS

I would like to acknowledge with appreciation to the

Faculty of Veterinary and Animal Hospital Universitas

Airlangga for the facilitation and support on the in vivo

study of this research.

REFERENCES

Anusavice J.K., Shen C, Rawis HR, 2013. Phillips of

Science of Dental Materials, 12

, Saunders Elsevier,

Missouri, 3-16; 48- 68; 307- 339.

Combe E, Trevor Burke FJ, Douglas W. Bernard, 2013.

Dental Biomaterials, Springer US, 222-276

Chung DDL, 2004. Use of polymers for cement-based

structural materials, Journal of Material Science 39,

2973 – 2978

Manappallil JJ,2016. Basic Dental Material, Jaypee

Brothers Medical Publishers, Ltd, Nepal, 3-61; 84-

167.

Noort, R.V.,2002, Introduction to Dental Material, 2nd

ed, Mosby, London, 6-12

Nugroho, Dr. Pramono, 2007, Pembuatan Semen Tambal

Gigi dengan Bahan Dasar Polimer, LIPI, Bandung

Dental Cement Physical and Mechanical Properties by In Vivo Approach

279

Wagh AS, 2016. Chemically Bonded Phosphate ceramics,

Twenty – First Century Materials with Diverse

Applications, 2

edition, Elsevier, Cambridge, 133-

138

ICPS 2018 - 2nd International Conference Postgraduate School

280