الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
This research aimed at investigating the antibacterial effect of
Octenidine dihydrochloride when incorporated in an experimental dental
flowable resin composite material. Different concentrations were used and
tested in order to increase the antibacterial effect without compromising the
mechanical properties of the resin composite.
A commercially available flowable resin composite material (Herculite
Ultra Flowable by Kerr Corporation) was used as a control group in this study.
The following properties were tested: diametral tensile strength, compressive
strength, flexural strength, water sorption, solubility, degree of conversion,
dentin bond strength, and the antibacterial activity against Streptococcus
mutans and Lactobacillus casei at different time intervals. Eight similar
specimens were made for every test in each group, and all specimens were
tested for all the previous properties.
Diametral tensile strength test was conducted by subjecting cylindrical
specimens to compressive loading using the universal testing machine till the
point of fracture. The load was applied vertically on the lateral portion of the
cylindrical specimen, producing tensile stresses perpendicular to the vertical
plane passing through the center of the specimen. The fracture load was then
recorded and the ultimate diametral tensile strength was calculated according to
a mathematical equation.
As for the compressive strength test, it was done by subjecting
cylindrical specimens to compressive loading using the universal testing
machine till fracture occurred. where the compressive strength was
automatically recorded and calculated using a computer software program.
Moreover, the flexural strength was obtained by subjecting bar shaped
specimens to a 3-point loading using a universal testing machine.
Summary and conclusions
135
Water sorption and solubility measures were recorded after one day and
repeated after 7 days immersion in distilled water. The different masses and
volumes of each disc were documented after each test, and the water sorption
and solubility values were obtained and represented from these numbers using
mathematical equations.
The degree of conversion was measured by chemical analysis using
FTIR (Fourier Transform Infra-Red Spectroscopy). Degree of conversion was
performed after 24 hours of photo curing.
Dentin bond strength test was assessed using shear bond strength.
Specimens were stored in an incubator at 37°C in 100% humidity for 24 hours,
then subjected individually to shear bond stress at cross head speed of 1
mm/min until fracture occurred. Shear bond strength was calculated by
dividing the maximum load by the cross-sectional area of the bonded interface.
Fracture mode analysis was observed using a stereomicroscope with a
magnification of 40X to determine the failure mode in each specimen.
The antibacterial activity of the Octenidine dihydrochloride was
assessed using the agar disc diffusion test. The antibacterial activity was
assessed at different time intervals against two different bacterial strains
namely Streptococcus mutans and Lactobacillus casei.
On investigating the diametral tensile, compressive, and flexural
strength results, group 1(control group) showed the highest mean values among
all the tested groups, followed by groups 2,3, and 4 respectively. The
mechanical properties of the formulated flowable resin composite were
significantly lower than that of the commercially available control group.
Adding to that, the incorporation of the antibacterial agent Octenidine
dihydrochloride significantly lowered the mechanical properties among the
tested groups.
Summary and conclusions
136
Regarding the water sorption and solubility values, group 1 (control
group) showed the lowest values in both tests, followed by groups 2,3, and 4
respectively. Incorporation of Octenidine dihydrochloride significantly
increased the water sorption and solubility values, however values were still
within the accepted ranges for clinical use.
Results of the degree of conversion measured at 24 hours of curing revealed
a significant increase in the degree of conversion of the commercially available
control group (group 1) in comparison to all the experimental resin composite
in this study. Also, group 2 showed a significant increase in the degree of
conversion when compared to the other two groups 3 and 4 which contain the
antibacterial agent Octenidine dihydrochloride. On the contrary, incorporation
of the antibacterial agent OCT showed a significant decrease in the degree of
conversion when compared to groups free of the OCT.
Concerning the dentin bond strength test the values shown in all groups
followed the same pattern of results shown in all other mechanical tests
mentioned previously, where group 1 showed the highest mean values followed
by groups 2 then groups 3 and 4 respectively. However only with group 4 the
values obtained were below that accepted for clinical use.
As for the antibacterial effect against Streptococcus mutans, both groups 1
and 2 contained no Octenidine dihydrochloride thus they exhibited no
antibacterial effect. However, groups 3 and 4 had a significant antibacterial
effect that decreased over time for the first 3 months, then significantly
increased after 6 months’ time. Regarding the antibacterial effect against
Lactobacillus casei, results were similar regarding groups 1 and 2, however the
antibacterial effect significantly increased over time in both groups 3 and 4.
Within the limitations of this study, the developed experimental resin
composite may be clinically attractive. Additional future evaluation of
biocompatibility, together with other mechanical and physical properties of the
experimental resin composite is recommended.
Summary and conclusions
137
Conclusions
Based on the results of this study as regards the effect of incorporating
different percentages of Octenidine dihydrochloride into experimental flowable
composite, it can be concluded that:
1. Octenidine dihydrochloride positively influenced the antibacterial
activity of the flowable resin composite against Streptococcus
mutans and Lactobacillus casei.
2. Adding Octenidine dihydrochloride to the experimentally formulated
flowable resin composite met the ADA specifications regarding the
diametral tensile strength, compressive strength, flexural strength,
water sorption, solubility, and degree of conversion.
3. Octenidine dihydrochloride had a negative effect on the bonding of
the experimentally formulated flowable resin composite to the
dentin.
Recommendations for further research:
1. In-depth exploration of the effect of using Octenidine dihydrochloride
together with different filler types, sizes and shapes while taking into
consideration the different patterns of filler distribution would be very
helpful.
2. More methodological work is needed on how to incorporate different
weight percentages of the antibacterial agent.
3. Further research might include chemical analysis and characterization of
the antibacterial agent, and possibly exploring the effects of combining
another antibacterial agent with the Octenidine dihydrochloride and
assessing the long-term effect on the material’s properties.
4. Although methodologically challenging, it would be very useful to
conduct longer term studies, and re-asses the material’s properties at
different time intervals