الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 139 |  |  |
| | | from | 139 | | |
Abstract
This study was conducted to evaluate the effect of the different methods
of fluroide application on enamel bleaching and its surface properties,those
methods included both fluoride incorporation within the bleaching agents and
post bleaching application of fluoride.
Forty human premolar teeth were used for this study and they were
divided into 4 equal groups as follows:
group 1: control group,teeth were kept in artificial saliva for 14 days.
group 2: teeth were bleached using 10% CP without any fluoridation.
group 3: teeth were bleached using 10% CP followed by 2% sodium fluoride
gel application after each bleaching application.
group 4: teeth were bleached using 10% CP with 0.11% incorporated fluoride.
The material was applied on the buccal surface of teeth for 8 hours per
day then removed and the teeth were stored in artificial saliva in a dark room at
37o C.
The treatment period lasted for 14 days then the teeth were examined for
color change,surface micro-hardness,EDX analysis for calcium and phosphorus
elements and they were also evaluated histologically by Scanning electron
microscopy and polarized light microscopy and the results was as follows:
Regarding the color change there was no change in color for the control
group whereas all the bleaching groups showed lightening in color after the
treatment period compared to the baseline with the same whitening efficacy
among them all.
93
The surface microhardness was decreased in all the bleaching groups
after 14 days of treatment compared to the baseline with different percentage,
group 2 that didn‘t receive any fluoridation showed the greatest hardness loss
(about 37%),followed by group 3 that received post bleaching fluoridation
(hardness decreased by 23%) while group 4 with the incorporated fluoride
showed minimal hardness reduction with about 8%.
At day 28 all bleaching groups showed hardness recovery to values very
close to those of the baseline.
EDX analysis showed increase in phosphorus percentage and reduction
in Ca percentage and subsequently reduction in Ca/P ratio in all bleaching
groups compared to the control group.
group 2 showed more calcium loss than the fluoridated groups while
group 4 showed less calcium loss than any other bleaching group.
SEM analysis showed surface alteration in all bleaching groups,group 2
showed irregular surface with deep erosive pattern, group 3 showed the same
pattern as group 2 but with less aggressive erosion while group 4 showed minor
dissolution and surface erosion.
PLM examination showed almost intact rodless enamel layer in group 4
indicating minor demineralization of enamel while group 2 and 3 showed loss
of rodless enamel indicating surface demineralization.