Exposed Hypersensitive Dentin Treated With Fluoride Iontophoresis With Remineralizing Agents

The goal of this clinical trial is to learn if the application of fluoride works to treat patients suffering from dentin hypersensitivity. It will also learn about the safety of using fluoride iontophoresis with Acidulated phosphate fluoride gel. The main questions it aims to answer are: Does the remineralizing agent have the ability to decrease dentin sensitivity? Researchers will compare Fluoride Iontophoresis with Acidulated Phosphate Fluoride gel , Casein phosphopeptides-Amorphus calcium phosphate (CPP-ACP), nano-hydroxyapptite (NHAP) and -active glass in decreasing dentin hypersensitivity . Participants will: * Application of remineralizing agent every 3 months * Visit the dental clinic once every 3 months for checkups and tests