ijhbr.comijhbr.com/word_file/october 2015 abstract 2.docx · Web viewThis test was conducted as per ASTM ... 88. 67. 96 ** Indicate the ... plastic teeth was significantly greater

International J. of Healthcare and Biomedical Research, Volume: 04, Issue: 01, October 2015, Pages 17-25

Original article:

A Comparative evaluation of shear bond strengths of denture base to cross linked

acrylic resin maxillary anterior teeth with and without retentive grooves - An in-

vitro study

Dr.D.Sudha Madhuri 1*, Dr.B.Sreeramulu2

1Associate Professor & Incharge, Dept.of Prosthodontics,Govt,Dental College & Hospital, Vijayawada Andhra

Pradesh, India.2Associate Professor & Incharge, Dept.of Prosthodontics,Govt,Dental College & Hospital, Afzalgunj,

Hyderabad ,Telangana, India

Corresponding author: Dr.B.Sreeramulu

Abstract:In our experimental study, the aim was to measure the shear bond strength exhibited by Denture base to cross linked

acrylic resin maxillary anterior teeth with and without retentive grooves on their ridge lap surfaces and to compare the bond

strengths of each maxillary anterior tooth type as the adequacy of shear bond strength of each Maxillary anterior resin teeth

to the acrylic denture base is questionable. Success rate of approximately 90% was obtained with vertical retentive grooves

on canines and central incisors. We believe that this method can be used to improve the bond strength of the teeth with the

denture base material and prevent their dislodgement from the denture base1,2

Key words : Shear bond strength, cross-linked acrylic resin teeth ,retentive grooves.

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Introduction:

During the past few decades, several scientific

developments were carried in the fields of Dental

materials and Prosthodontics to produce denture

base materials that exhibited excellent fit,

dimensional stability ,strength, tissue tolerance,

ease of fabrication ,esthetics and are economical.

Though many types of denture base materials were

developed, acrylic polymers remained as the most

commonly used ones since their introduction by

Harold Veron in 1937.Ever since then, there has

been constant evolvement of the material to

achieve best results.Acrylic resin teeth are

preferred as functional portions with acrylic resin

denture base material as they became integral part

of the denture by their chemical bonding resulting

in an overall stronger one unit denture.

However there are several factors which resulted in

poor bonding of acrylic resin teeth to the denture

base like faulty boil out procedures, residual wax

on ridge lap surfaces of teeth, careless application

of tin foil substitutes and other separating medium

like sodium alginate to teeth leading to

contamination of their ridge lap surfaces.

The resistance to fracture of acrylic resin teeth from

denture base depends on SHEAR BOND

STRENGTH which gives an indication of material

performance under conditions of static loading.3,4

Attempts to increase the strength of the bond

between acrylic resin teeth and heat cured denture

base resin include

1. Grinding the glossy ridge lap surface of resin

teeth.

2. Painting the ridge lap surfaces of teeth with

monomer polymer solution.

3. Cutting retentive groves in the ridge lap

surface of teeth.

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Retentive grooves placed in the ridge laps of

denture teeth, increase the area available for

physical and chemical bonding and secure the teeth

to the base firmly.5,6

Considering the developments in heat cure acrylic

denture base resins and improvements in cross-

linked acrylic resin material teeth, the hypothesis

for this study were

1.The shear bond strength of cross-linked acrylic

resin teeth with grooves cut on their ridge-lap

surface would be higher than those without

grooves.

2.The shear bond strengths of all three types of

cross linked acrylic resin maxillary anterior

teeth used in this study would be similar

The Aims of this study were

1.To compare the shear bond strengths of denture

base to acrylic resin teeth with and without

retentive grooves cut on their ridge lap surface.

2. To determine whether central incisor or lateral

incisor or canine acrylic resin teeth used in this

study, has higher bond strength to denture base.

Materials and methods:

The glossy ridge-lap surface of 90 cross-linked

acrylic resin maxillary anterior teeth of which, 30

were central incisors,30 were lateral incisors and 30

were canines.The specimens were divided into

three similar groups,

Group A: No further tooth preparation was carried

out.

Group B:A mesio-distal groove 2mm deep and

2mm wide was cut into the ridge-lap surface of

tooth.

Group C:A vertical groove 2mm deep and 2mm

wide was cut into the center of the

ridge-lap surface of tooth extending

half way up the lingual surface.

Similar teeth were mounted in numbers of ten on

triangular shaped wax molds to produce nine wax

mold specimens and then flasked.The wax was

removed by flushing away with hot boiling water.

After the process of dewaxing, the specimens were

allowed to cool. At this stage plastic surfaces of

teeth were painted with one coat of separating

medium. Six acrylic mold specimens containing 10

acrylic resin teeth each were then prepared by

conventional curing method of which three

specimens were cured with DPI brand resin

material and other three with TREVALON brand

resin material.

The monomer to polymer ratio was maintained at

1:3 by volume for all the samples. A pipette was

used to transfer the required volume of monomer to

a clean, dry, air tight porcelain mixing jar.

Thepolymer was measured with a measuring

cylinder and transferred to the jar containing

monomer. Thorough mixing was done with a clean

stainless steel spatula and the jar was closed till the

mix reached dough stage. The resin was removed

from mixing container and rolled into a rope like

form and placed into upper half of the mold. The

flask was re-assembled and was bench pressed by

applying pressure incrementally. Pressure was

applied until the major portions of the edges of the

flask closely approximate one another. The flask

with acrylic resin was allowed to bench cure for

15min.

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We are now with

IC Value 5.99

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Acrylic Resin Teeth With Horizontal Groove,No Groove And Vertical Retentive Groove

Shear Bond Strength Testing:

The specimens were subjected to testing on a

universal testing machine INSTRON (model 6025).

The test was initiated by applying load to the

specimen at a specified cross head speed of

5mm/min at an angle of 130° to the long axis of

the tooth until fracture occurred. The deflection

was measured either by the gauge under the

specimen in contact with it in the centre of support

pan or by measurement of the motion of loading

hose relative to the support. This test was

conducted as per ASTM-D790. The site of

fracture of tooth from resin model was recorded

as through the tooth, through acrylic resin and at

the tooth acrylic interface of all the teeth fractured

at tooth acrylic interface.

Instron

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Instron Machine 3 Point Bend Test


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FORCE (Kg / cm2) REQUIRED TO SEPARATE

CENTRAL INCISORS FROM CAST

Name of the

Denture

Base Resin

Group –

A

No

Groove

Group – B

Horizontal

Groove

Group

– C

Vertical

Groove

DPI

16

10

15

8

19

28

33

16

25

13

19

20

22

24

20

32

38

35

31

29

25

44

38

33

27

45

46

37

39

43

Group –

A

Group – B Group –

C

TREVALON

22

26

18

27

23

20

33

40

42

39

39

29

19

30

48

52

32

40

35

24

46

38

42

53

45

51

36

44

52

47


Statistical analysis:

The results were subjected to a statistical analysis

using a one way analysis of variance (ANOVA)

and were appropriate.

Results:

Shear bond tests:

The results were given in table.

Table I:

The maximum bond strength obtained among the

specimens of group A for Central incisor teeth is 42

kg/cm2 while the minimum is 8 kg/cm2. (Mean and

SD 22.1765 ± 8.5676)


specimens of group B is 52kg/cm2 while the

minimum is 19kg/cm2. (Mean and SD 31.8889 ±

9.3676)


specimens of group C is 53kg/cm2 while the

mFORCE (Kg / cm2) REQUIRED TO SEPARATE

CENTRAL INCISORS FROM CAST

Table II:


specimens of group A for lateral

Incisor teeth is 24kg/cm while the minimum is

6kg/cm2. (Mean and SD 13.7059 ± 4.32123)


specimens of group B is 32kg/cm2 while the

minimum is 9kg/cm2. (Mean and SD 17.0556 ±

6.8382)


specimens of group C is 55kg/cm2 (Mean and SD

29.5556 ± 11.6023)


20

21

21

FORCE (Kg / cm2) REQUIRED TO

SEPARATE LATERAL INCISORS FROM

CAST

Name of the

Denture

Base Resin

Group –

A

No

Groove

Group – B

Horizontal

Groove

Group –

C

Vertical

Groove

DPI

8

13

7

12

11

6

15

13

9

11

10

12

9

15

10

18

8

11

12

13

15

25

27

23

19

13

18

15

24

26

Group –

A

Group – B Group –

C

TREVALO

N

23

15

13

16

14

17

16

21

23

24

24

23

32

24

16

24

21

23

14

28

34

29

33

42

37

28

31

53

55

46


Table III:


specimens of group A for Canine teeth is 51 kg/cm2

while the minimum is 13 kg/cm2. (Mean and SD

26.8824 ± 11.0277).


specimens of group B for Canine teeth is 60kg/cm2

while the minimum is 15kg/cm2. (Mean and SD

33.8333 ± 13.7595).


specimens of group C for Canine teeth is 118kg/cm2

while the minimum is 21 kg/cm2.

TABLE III

FORCE (Kg / cm2) REQUIRED TO SEPARATE

CANINE

TEETH FROM CAST

Name of

the

Denture

Base Resin

Group – A

No Groove

Group –

B

Horizont

al Groove

Group –

C

Vertical

Groove

DPI

17

14

**

24

19

15

13

25

20

18

35

**

24

15

20

17

23

27

26

19

39

26

28

34

33

27

21

**

42

56

Group – A Group – B Group –

C

TREVALO

N

27

31

29

38

40

51

39

37

**

55

43

54

42

38

60

33

35

41

68

88

102

118

121

132

88

67

96

** Indicate the teeth fractured during deflasking

Discussion: Acrylic resin has become almost universal since its

introduction in 1937 as a denture base material as


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well as the component of the resin cross-linked

teeth.7,8This study was conducted to compare the

shear bond strengths exhibited by denture base to

maxillary anterior resin teeth with and without

retentive grooves made on their ridge-lap surfaces.

This study also concentrated on the comparison

of shear bond strengths exhibited by cross linked

acrylic resin maxillary central incisors, lateral

incisors and canines used in this study.

The results showed that the mean bond

strength exhibited by those specimens without

retentive grooves was 21.231Kg/sqcm , for those

with horizontal grooves was 27.503Kg/sqcm and

for those with vertical retentive grooves was

45.648Kg/sqcm .This indicated that specimens

with vertical retentive grooves showed

significantly higher bond strength than those with

horizontal grooves and without grooves. The mean

bond strengths obtained for central incisor was

31.928Kg/sqcm, for lateral incisor was

20.164Kg/sqcm and for canine was

42.990Kg/sqcm, the highest among the three tooth

types tested in this study.The Vertical retentive

grooves showed a statistically significant superior

retention in all tooth types. The vertical groove is

closer to the point of application of force. A short

lever arm requires greater force to separate the

tooth from denture base.Canine teeth bonded more

securely to denture base resin than central incisors

and lateral incisors. Thisfinding may be accounted

for the ridgelap of canine presenting a greater

surface area for bonding to acrylic resin.

Morrow et.al using a tensile force to separate

teeth from denture base resin found that from

denture base resin found that bond strength of high

impact resin to plastic teeth was significantly

greater than standard resin.In the present study a

combined shear compressive force was applied at

an angle of 130degrees to simulate clinical

conditions.

Non significant stastical interactions was noted

between tooth type and the retentive grooves .A

significant statistical interaction was found between

tooth type and denture base resin. Canine teeth

bonded more securely to denture base resin than

central and lateral incisors. This finding may be

accounted for the ridge lap of canine presenting a

greater surface area for bonding to acrylic resin. A

significantly greater force was required to separate

teeth from TREVALON than from DPI. Morrow et

al., using a tensile force to separate teeth from

denture base resin, found that bond strength of high

impact resin to plastic teeth was significantly

greater than standard resin. In the present study, a

combined shear compressive force was applied at

an angle of 130° to lingual surface of teeth to

simulate clinical conditions. A statistically

significant interaction was found between denture

base resins and tooth type. TREVALON showed a

better bond strength with all the types of teeth and

it Acrylic resin has become almost universal since

its introduction in 1937 as a denture base material

as well as the component of the resin cross-linked

teeth . This study was conducted to compare the

shear bond strengths exhibited by two brands of

conventional heat cure denture base resin

materials DPI and TREVALON to cross linked

acrylic resin maxillary anterior teeth of

PREMADENT brand. This study also

concentrated on the comparison of shear bond

strengths exhibited by cross linked acrylic resin

maxillary central incisors, lateral incisors and

canines used in this study.

The results showed that the mean bond strength

exhibited by DPI heat cure denture base material

was 22.580 kg/cm2 while the same for

TREVALON was 40.401 kg/cm2 which indicated

that TREVALON has a better bond strength

compared to DPI denture base material. The mean

bond strength for each tooth type tested also


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showed significant difference. The mean bond

strength obtained for central incisor was 31.928

kg/cm2 , for lateral incisor was 20.164 kg./cm2,

while that exhibited by canine tooth was 42.990

kg./cm2, the highest bond strength among the three

types of teeth tested in this study.

Conclusions:

Within the limitations of the methodology of the

study, the main conclusions which can be drawn

are as follows.

A significantly greater force was required

to separate teeth with retentive grooves

than without grooves from the denture

base..

Canine tooth type with vertical retentive

grooves exhibited higher bond strength

when compared to other tooth types tested

in this study..

No consistent trend was noted in the site

of fracture for teeth with horizontal and

vertical retentive grooves on application

of force, all the teeth without retentive

grooves fractured at the tooth acrylic resin

interface.

An increase in the ridge lap surface area of

teeth resulted in an increase in shear bond

strength

References

1. CUNNINGHAM JL.Bond strength of denture teeth to acrylic bases. J Dent 1993; 21(5): 274-280.

2. Jakahashi Y, Chain J.Bond strength of denture teeth to denture base resins.International journal of

prosthodontics. 2000;13(1): 59-65.

3. Thean HP, Chew CL, Goh KL.Shear bond strength of denture teeth to base, a comparative study.

Quintenssence Int. 1996 ;27(6):425-428.

4. John N Anderson.The strength of the joint between plastic and copolymer acrylic teeth and denture base

resins. British Dental Journal. 1958; 6: 319-320.

5. GeertsAVM.A comparison of the bond strength of the microwave and water bath cured denture

material. JPD.1990;70:406-409.

6. Harrison WM, Stansburg BE. The effects of joint surface contour on the transversal strength of repaired

acrylic resins. JPD.1970;23:464.

7. Consani S, Stolf WL, Ruhnke LA.Comparative study of bonding of acrylic teeth and resin bases. JPD.

1993;690.

8. Can G, KhasuG.An evaluation of the bond strength of plastic teeth to acrylic denture base material. Ankare

Umin Ilekein Jak Derg. 1990;17(1): 97-101.


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ijhbr.comijhbr.com/word_file/october 2015 abstract 2.docx · Web viewThis test was conducted as per ASTM ... 88. 67. 96 ** Indicate the ... plastic teeth was significantly greater