الفهرس 
Enamel demineralization (white spot lesions)Only 14 pages are availabe for public view
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Abstract
Enamel white spot lesions are the earliest microscopic signs
of demineralization under intact enamel, which may or may not
lead to the development of caries (cavitation). The reason for the
white spots is that the pathogenic bacteria have leached out a
certain amount of calcium and phosphate ions from the enamel
layer by the organic acids produced by these bacteria. Therefore,
the increase in calcium or fluoride concentrations in the oral fluids
was found to enhance lesion remineralization.
Although fluoride therapy has been the cornerstone of cariesprevention and remineralization strategies since the introduction of
water fluoridation schemes over 5 decades, but it has many
limitations and drawbacks. Therefore the introduction of natural
products has been used as promising sources for novel therapeutic
agents. The majority of studies of natural products in the field of
oral health have focused on their antimicrobial activities. Very few
reported on the effects of natural products on the inhibition of
dental erosion or decalcification processes of dental hard tissues.Gum arabic is considered to have an ability to enhance tooth
remineralization, because of its high concentration of calcium.
Aim of the study:
The aim of this study was to investigate the remineralizing
effect of gum arabic and the effect of sodium fluoride on artificial
enamel white spot lesions qualitatively and quantitatively.
Materials and Methods:
Twenty-one caries-free human premolars were collected. Since
teeth may differ in many properties as the enamel thickness, there
was standardization through the use of the same tooth to be
investigated before and after treatment.
Samples were randomly divided into 3 groups, 7 premolars each,
according to the treatment solution used as follows:
group I: treated with 10 milligram per milliliter gum arabic
solution.
group II: treated with sodium fluoride at 1000 parts per
million.
group III: treated with distilled water.All samples under all groups were first evaluated regarding their
enamel surface topography, surface Ca content and surface microhardness to act as a baseline, and during this the samples were
named as Subgroups A (IA, IIA and IIIA).
Then, all samples under all subgroups were subjected to artificial
enamel white spots formation by immersion in a specific
demineralizing solution, and after lesions creation they were
evaluated again and named as Subgroups B (IB, IIB and IIIB).
Samples were subsequently subjected to the three different
treatment solutions previously mentioned and were named as
Subgroups C as follows:
Subgroup IC: Treated with GA.
Subgroup IIC: Treated with NaF.
Subgroup IIIC: Treated with DW.
Teeth under different groups have received their treatment
solutions in the form of pH cycles for 20 days, to simulate the
fluctuation of demineralization and remineralization in the oral
cavity.Samples evaluation was done using: Environmental Scanning
Electron Microscope, Energy Dispersive X-ray Micro-analyzer, and
Vicker’s micro-hardness tester.
Results:
I-Results of enamel surface topography:
The environmental scanning electron microscopic
examination of the middle part of the buccal surface of premolars
before demineralization (subgroups IA, IIA & IIIA), revealed intact
aprismatic surface layer with obvious perikymata ridges and few
number of enamel rod ends at the perikymata grooves.
After demineralization (subgroups IB, IIB & IIIB), enamel
has shown etching patterns of either type I or irregular erosions in
the form of craters, cracks (both narrow & wide were found) and
cavitations.
The examination after treatment revealed similar signs of
enamel remineralization in gum arabic and sodium fluoride
subgroups (IC and IIC respectively) in the form of regeneration of
surface uniformity, prism cores appearing largely filled in with a
consequent decrease of their diameter, globular precipitatesaccumulating inside prism cores and the characteristic keyhole
pattern of the enamel rods was well defined without any signs of
prism cores dissolution, compared to the subgroup of distilled water
(IIIC) which showed no significant improvement in the enamel
surface topography after treatment.
II-Results of Enamel surface mineral content:
There was a highly statistically significant decrease in
enamel surface calcium weight percent values after
demineralization (subgroups IB, IIB & IIIB).
A highly statistically significant increase in calcium values
was similarly noticed in subgroups IC and IIC after treatment with
gum arabic and sodium fluoride solutions respectively, compared to
the demineralized enamel of the corresponding groups but not
reaching the original values of control enamel, while subgroup IIIC
(treated with distilled water) showed no significant difference in the
calcium values after treatment.III-Results of enamel surface micro-hardness:
There was a highly statistically significant decrease in
enamel micro-hardness in all groups after demineralization (groups
IB, IIB & IIIB).
A highly statistically significant increase in enamel microhardness values was similarly noticed in subgroups IC and IIC after
treatment with gum arabic and sodium fluoride solutions
respectively, compared to the demineralized enamel of the
corresponding groups but not reaching the original values of control
enamel, while subgroup IIIC (treated with distilled water) showed
no significant difference in enamel micro-hardness after treatment.