compare the effectiveness of Eggshell derived nano-Hydroxyapatite with and without fluoride and conventional fluoride containing tooth paste versus conventional desensitizing fluoride containing tooth paste on dentinal tubule occlusion and dentin mineral deposition.

Recently advanced nanotechnology has taken a wide leap in improving the various measures in the treatment of hypersensitivity by its nanoparticles. Nanoparticles can easily penetrate into dentin tubules, which could act as mineralizing agents that block fluid movement within the dentin tubules when combined with various agents.

Hydroxyapatite (HAp) is the major inorganic component of natural teeth and bone. Nano-sized particles of hydroxyapatite are similar to the apatite crystals of tooth enamel in morphology and crystal structure and has been studied as a biomimetic material for the reconstruction of tooth enamel suffering from mineral loss because of its unique potential for remineralization. Nano-hydroxyapatite (n-HAp) was considered a promising active ingredient used for the treatment of DH due to high biocompatibility and bioactivity. In toothpastes, HAp was included in the form of nanocrystals because they dissolve easier in this form. Crystals of n-HAp included in dental products have a dimension of 50-1000 nm, which enables them to act like fillers. These products can penetrate and block the exposed dentinal tubules which are responsible for DH

Inclusion Criteria:

• Adult Patients Aged 18-60
• Males or females.
• Good oral hygiene
• Absence of abnormal occlusion habits (e.g. bruxism, nail biting, tooth clenching and mouth breathing).
• Teeth with hypersensitivity, VAS ≥5
• Co-operative patients who show interest to participate in the study.

Exclusion Criteria:

• Patients with known allergic or adverse reaction to the tested materials.
• Systematic disease that may affect participation.
• Xerostomic patients.
• Patients with bad oral hygiene
• Patients with orthodontic appliances, or bridge work that might interfere with evaluation
• Patients who did any periodontal surgeries within the previous 6 months.
• Patients with physical disabilities

• This study is a double blinded study, the participants as well as the assessors will be blinded. The operator will not be blinded to apply both interventions following the manufacturer's instructions.
• Double blinded study design is the recommended design for studies of DH. (Holland et al., 1997)
• Outcome assessors and analyst (M.S and D.E) will be blinded to the intervention group assigned to the patients.
• Operator (SH.G) will not be blinded.