This study aims to evaluate the effect of the addition of chlorohexidine gluconate (CHX) (powder) on some physical, mechanical properties and antimicrobial effect. In this study two hundred and forty samples of heat cured acrylic resin (Major base-2) were prepared and divided into different groups.
Control group (without the addition of CHX) and experimental groups (with the addition of CHX (powder) at (1%, 2%, 3%)) to evaluate transverse strength, tensile strength, surface hardness, dimensional accuracy, deflection, residual monomer in addition to antimicrobial effect for heat cured acrylic resin before and after the addition of CHX (powder).
Results showed a statistically significant difference at (p0.05) between control and experimental groups. The addition of CHX (powder) into heat cured acrylic resin increases its flexibility in addition to it's antimicrobial effect. Group of 1% CHX has the highest value of transverse strength, tensile strength, surface hardness and dimensional accuracy after control group.
In addition to its antimicrobial effect, CHX increases the flexibility of heat cured acrylic resin. As the concentration of added CHX increased, the flexibility of heat cured acrylic resin specimens will be increased.
resin were introduced as a denture base material in 1937
(1,2)
. In spite of the several
limitations of this material, it still remains the most popular material of choice
(3-5)
. Many
studies had been introduced for modification of this material to be more flexible,
comfortable, less susceptible to fracture and more acceptable by the patient
(6-14)
.
chlorohexidine gluconate (powder) (CHX) is the most intensely researched preventive agent
in dentistry
(15)
,it has been introduced since 1969, it has
antimicrobial
effect against gram positive,
gram negative, yeast and facultative aerobic and anaerobic flora in addition to limited vircucidal
effect
(16-18)
. It has been used as a disinfectant solution
(19-22)
, root canal irrigant
(23)
, treatment of
denture stomatitis
(24)
, mouthwash
(25)
, it also can be incorporated into periodontal dressing
(26)
.
Several research has been introduced to study the topical, sustained-release form of CHX by
using of a sustained-delivery system of CHX which was applied directly to dental appliances,
such a dosage form would be capable to release CHX at low therapeutic level over a long period
of time and thus would be effective in the prevention of plaque formation and prevent the side
effect of CHX(better test and tooth staining)
(27-32)
.
MATERIALS AND METHODS
Two hundred and forty samples of heat cured acrylic resin (Major base 2) were prepared and
divided into:
Control group: 60 samples of heat cured acrylic resin without the addition of CHX.
Experimental group :180 samples of heat cured acrylic resin with the addition of CHX at
(1%, 2%, 3%).
Acrylic resin specimens were prepared in a mold made by investing a hard elastic foil for
specific dimensions (according to each test as mentioned bellow) in dental stone that were mixed
in a water/powder ratio of 32gm/100ml and placed in the lower half of the flask, then glass slab
was placed against the first half till the stone set. After final setting of stone, a conventional
flashing procedure was used for the preparation of acrylic resin samples
(33)
.
Acrylic resin samples were mixed and manipulated according to manufacturer directions.
Cure was taken to avoid porosities due to entrapment of air bubbles. Trail closure was
performed. The specimens were cured in water path with conventional curing cycle, the
specimens processed at 74°C for 90 minutes, then the temperature of water path raised to boiling
100°C for 30 minutes(according to manufacture instructions). The samples left for bench cooling
for 30 minutes then it finished using tungsten drill and sand paper at low speed
(34)
. All samples
used in this study were evaluated for the presence of porosity by examining them under
reflecting light microscope(LOMO Micmed 2) before being tested
( 6, 35, 36)
. After that the
samples stored in distilled water at 37°C for two periods of time (2days and 7 days), then the
following tests were done to evaluate:
1.
Evaluation of transverse strength and deflection : The samples of this test were prepared in
dimensions of 65*10*2.5±0.03mm(length, width and thickness respectively)
(37)
. The test was
done by using a 3 points bending on an Instron universal machine(Wolpert, Germany). The
samples were deflected until failure occurred. The transverse strength was calculated using the
following equation:
Transverse strength(N/mm
2
)=3/2×PI×bd
2(38)
b: the sample width (mm) d: the sample thickness(mm)
I: the span length(mm) P: the peak load(N)
2
The deflection was calculated by using digital vernia in accuracy of 0.001mm Figure(1).
2.
Evaluation of tensile strength: The samples of this test were prepared with dimensions of
90*10*3±0.03 mm(length, width and thickness respectively). The tensile strength was evaluated
by using Terco universal testing machine . The amount of force applied was 0.1 KN /sec. The
results were recorded from a special program on computer of tensile machine for each sample
(7 )
.
3.
Evaluation of surface hardness test: The samples of this test were prepared with dimensions
of 30*15*3±0.03 mm(length, width and thickness respectively). The polished surface was tested
for hardness at five different locations then the mean is taken for each surface by using Rockwell
hardness tester with an indenter in the form of round steel ball (6.359mm in diameter). The
sample was first subjected to a fixed minor load of 10Kg, then load of 50Kg was applied to the
sample and the Rockwell hardness number was recorded after application of this load by 15 sec
(39)
4.
Evaluation of dimensional accuracy: The samples of this test were prepared in dimensions of
65*10*2.5±0.03mm(length, width and thickness respectively) in which their volume standard is
equal 1625mm
(37)
,measurement on three dimensions were done by using digital caliper accuracy
of 0.001mm
(6,7)
.
5.
Evaluation of residual monomer: The samples of this test were prepared with dimensions of
20*20*3±0.03 mm(length, width and thickness respectively)
(36)
. The samples immersed in
distilled water in sealed glass container , then the collected supernated medium was monitored
using quartiz cell ultraviolet visible spectrophotometer (CECIL 2000) ( =254nm) compared with
pure monomer. A standard linear calibration curve of methyl methacrylate concentration as a
function of absorbency at 254nm was obtained using MMA standard aqueous solution ranged
0.005-0.125ggm/ml
(40)
. The results were expressed as a percentage of released residual monomer
mass with respect to weight of special means
(41&42)
.
6.
Evaluation of antimicrobial effect: The samples of this test were prepared as filter disc of
(6mm in diameter), the ability CHX to inhibit bacterial growth in vitro was estimated by Disk-
Diffusion test
(43)
. Nutrient agar was used, primary culture was prepared by taking a swap from
oral cavity by using sterile loop to test tube contain normal saline. After complete incubation,
measuring the inhibition zone around the disc was done to determine the antimicrobial effect.
RESULLTS
Analysis of the mean, standard deviation and Duncan's multiple comparison test showed that
the experimental group of 1% CHX has the highest value of transverse strength, tensile strength,
surface hardness and dimensional accuracy after control group for 2 and 7 days period Tables(1-
4) .While experimental group of 3% CHX showed the lowest value of transverse strength, tensile
strength , hardness and dimensional accuracy than control group after 2 and 7 days.
Duncan's multiple comparison test have shown statistically significant difference between
control and experimental groups in transverse strength, tensile strength and surface hardness
after 2 and 7 days(at p 0.05) Tables(1-3). While for dimensional accuracy; Duncan's multiple
comparison test Table(4) Showed that there was a statically significant difference between
control and experimental groups except that there was no statistically significant difference in
dimensional accuracy between control and experimental group of 1%CHX after 2 and 7 days
and between experimental groups of 2% CHX and 3% CHX after 7 days at (p 0.05). One way
analysis of variance Tables(5-8) revealed that there was a statistically significant difference in
transverse strength, tensile strength, surface hardness and dimensional accuracy between control
and experimental groups after 2 and 7 days at (p 0.05).
3
Table (1): Mean, Standard Deviation and DRMT for the effect of CHX on Transverse Strength
of Heat Cured Acrylic Resin
Table (2) Mean, Standard Deviation and DRMT for the Effect of CHX on Tensile Strength of
Heat Cured Acrylic Resin
Table (3) Mean, Standard Deviation and DRMT for the Effect of CHX on Surface Hardness of
Heat Cured Acrylic Resin
sample
After 2 days
Mean( N/mm
2
) SD DMRT
After 7 days
Mean( N/mm
2
) SD DMRT
control
94 0.015 A
91 0.077 A
1%CHX
22 0.094 B
25 0.074 B
2%CHX
20 0.060 B
23 0.037 C
3%CHX
15 0.058 C
19 0.083 C
sample
After 2 days
Mean(N/mm
2
) SD DMRT
After 7 days
Mean(N/mm
2
) SD DMRT
control
56.9 0.054
A
54 0.041
A
1% CHX
39.6 0.035
B
43.6 0.084
B
2%CHX
24.5 0.014
B
26.8 0.073
B
3%CHX
20.1 0.016
C
22.8 0.016
C
sample
After 2 days
Mean SD DMRT
After 7 days
mean SD DMRT
control
110 0.051 A 104 0.0531 A
1% CHX
69 0.051 B 63 0.018 B
2%CHX
67 0.050 B 60 0.051 B
3%CHX
60 0.014 B 55 0.0146 B
4
Table (4) Mean, Standard Deviation and DRMT for the Effect of CHX on Dimensional
Accuracy of Heat Cured Acrylic Resin
Table (5): One Way ANOVA of the effect of CHX on Transverse Strength of Heat Cured
AcrylicResin
*Statistically Significant at p 0.05
Table (6): One Way ANOVA of Effect of CHX on Tensile Strength of Heat Cured Acrylic
Resin
*Statistically Significant at p 0.05
Table (7): One Way ANOVA of the Effect of CHX on Surface Hardness of Heat Cured Acrylic
Resin
*Statistically Significant at p 0.05
sample
After 2 days
Mean* SD DMRT
After 7 days
Mean* SD DMRT
control
11624.890 0.01 A 11624.86 0.04 A
1% CHX
11624.84 0.01
A 11624.83 0.01
A
2%CHX
11624.61 0.04
B 11624.40 0.01
B
3%CHX
11624.39 0.03
C 11624.18 0.07
B
After 2 days
After 7 days
S.O.V DF
MS
F*
DF
MS
F*
Factor
3 7101.1 482.1 3 6231.1 21.3E04
Error
16 1.46
16
Total
19
19
After 2 days
After 7 days
S.O.V
DF
MS
F*
D
F
MS
F*
Factor
3 3.067
487.
1
3
8.305
3
817.
9
Error
16 0.039
16
0.010
2
Total
19
19
After 2 days
After 7 days
S.O.V DF MS
F*
DF
MS
F*
Factor
3 2421 52.18 3 1912. 31.35
Error
16 77.2
16 36.6
Total
19
19
5
Excerpt out of 10 pages
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- Quote paper
- Amer Taqa (Author), Nada Z. Mohammed (Author), Alia'a W. Alomari (Author), 2011, The Effect of Addition Chlorohexiidine Gluconate (Powder) on the Properties of Heat Cured Acrylic Resin, Munich, GRIN Verlag, https://www.grin.com/document/431815
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