Objectives: The aim is to investigate the effect of Eggshell powder solution (ESPS)
desensitizing agents as dentin surface pretreatments on thickness of hybrid layer of a direct resin
composite restoration bonded with etch and rinse adhesive systems.
Methods: A flat dentin occlusal surface will be prepared on extracted molar using a low speed
diamond saw under water coolant. Teeth will be randomly divided into three main groups according
to dentin surface pretreatment. First group, no dentin pretreatment (A1), second group Egg shell
pretreatment applied before acid etching (A2) and third group, Egg shell pretreatment applied after
acid etching (A3). A Teflon mold will be used to build up resin composite directly. Teeth will be
sectioned perpendicular to adhesive joint to obtain 0.9±0.1 mm in thickness slabs. All samples
will be examined under scanning electron microscope (SEM) and thickness of hybrid layer will
be measured. Moreover energy dispersive analytical x-ray (EDAX) analysis will be used to count
different minerals at tooth restoration interface.
Results: The SEM analysis showed that; there are established significant differences in
the thickness of hybrid layers among all tested groups. The EDAX analysis showed increased
quantitative amounts of Ca atomic % and P atomic % for the ESS treated groups.
Conclusion: Eggshell solution when used as desensitizing agent can significantly increase the
hybrid layer thickness.