Abstract
Objective The aim of this study was to assess the combined effect of erbium:yttrium-aluminum-garnet
(Er:YAG) laser and mineralizing agents including casein phosphopeptide-amorphous calcium
phosphate (CPP-ACP) and fluoride in improving the resistance of demineralized dentin
at new demineralization process.
Materials and Methods One hundred and twenty healthy dentin surfaces were prepared and demineralized using
acidic solutions. Primary microhardness was measured (h1), and samples were randomly
divided into six groups. Each group received a different protocol as follows: Group
A (control group): no additional treatment, Group B: applying a fluoridated gel, Group
C: applying a CPP-ACP-containing cream, Group D: irradiation of Er:YAG laser, Group
E: irradiation of Er:YAG laser combined with the application of a fluoridated agent,
and Group F: irradiation of Er:YAG laser combined with the application of CPP-ACP-containing
cream. Microhardness values were measured afterward (h2). Then, all the groups were
re-exposed to acidic solution, and microhardness was measured for the third time (h3).
The microhardness data were analyzed using analysis of variance and Scheffe's post
hoc test.
Results Although application of mineralizing agents increased the microhardness of demineralized
dentin in comparison with the control group, no significant difference was observed
using two agents. Comparison of laser groups showed an increase in microhardness only
after the irradiation of Er:YAG laser combined with the application of a fluoridated
agent. Demineralizing process reduced the microhardness values in all the groups,
but the application of a CPP-ACP agent caused the least reduction among the laser
irradiated groups. Comparison of hardness changes at the beginning and end of the
experiment did not show any significant differences between the groups.
Conclusion Comparison of treatment modalities used in this study exhibited that fluoride had
the greatest impact on dentin resistance. Laser irradiation on demineralized dentin
did not increase the hardness or resistance to acidic attacks.
Keywords
casein phosphopeptide-amorphous calcium phosphate - demineralized dentin - erbium:
yttrium-aluminum-garnet laser - mineralizing agents