The aim of this study is to compare the efficacy of dentine hypersensitivity reduction using in office paste formula containing nanoHydroxyapatite with the commercially available fluoride (duraphat) and a placebo in treating hypersensitivity in a single visit.

Following the approval of the Research Ethics Committee of Riyadh college of Dentistry and Pharmacy (The Institutional Review Board), a randomized double blind single treatment controlled clinical trial will be carried out on 60 patients (-- males and -- females) between the age group of 18 to 45 years, visiting the out-patient clinics of Riyadh Colleges of Dentistry and Pharmacy during the period between October and December.

The protocols for the study will be developed as per the guidelines for the design and conduct of clinical trials on dentinal hypersensitivity and in accordance with the Declaration of Helsinki and Guidelines for Good Clinical Practice. Prior to the start of the study patients will be given both verbal and written information about the process and an appropriate signed informed consent form will be obtained.

Only subjects demonstrating two hypersensitive teeth that satisfied the tactile and airblast hypersensitivity enrolment criteria, qualified to participate in the study. Qualified subjects will be randomly defined to one of the three study groups in order to have 20 subjects per treatment group:

• Study 1: nanoXIM care paste, fluoride-free (test group)
• Study 2: fluoride paste
• Study 3: placebo group (positive control group).

Subjects selected will undergo thorough clinical examination, followed by oral prophylaxis, oral hygiene instructions and dietary counseling. After the teeth isolation with cotton rolls, changes in the dentin sensitivity to tactile (dental explorer), thermal stimuli (drops of melted ice) and air stimuli (blast from dental syringe) will be evaluated. Following application of the stimuli, responses will be evaluated and assessed by the Visual Analog Scale (VAS). The survey form will be completed by the examiner to have a baseline prior to paste application in the first visit. The survey contains five questions, rated on a 10-point scale, assessing:

1. Degree of pain.
2. Duration of pain.
3. Intensity of pain.
4. Tolerability of pain.
5. Description of pain.

Data Analysis

The study patients will be randomly assigned into 3 groups (N, F and P) equal groups of 20. The randomization process will be made using a computer-generated random table. Excel software (Micro- soft) will be used for randomization. The pastes used on the study labeled N, F and P respectively, will be completely wrapped not allowing the pastes applicant or any other member of the research team to know what test paste will be applied on the patients. The patients will be blinded by not letting them know which agents will be applied. The chief investigator, the first author in this study, will coordinate the entire trial and recruited the various operators for the same.

Inclusion Criteria:

• Hypersensitive areas on facial surfaces of the teeth (incisors, canines, premolars, and first molars with exposed cervical dentin) with at least two teeth scoring "pain (scale stimuli test, scores 2 and 3)" during application of stimulus (airblast and tactile sensitivity test)
• Good periodontal health (no probing depth > 4 mm) with no other conditions that might explain their apparent dentin hypersensitivity
• Good overall physical health
• Age between 18 and 45 years
• Provision of written informed consent
• Patient willing to participate in the study

Exclusion Criteria:

• Chipped teeth
• Defective restorations
• Fractured undisplaced canines
• Deep dental caries
• Deep periodontal pockets
• Orthodontic appliances
• Dentures or fixed dental prostheses that would interfere with the evaluation of hypersensitivity
• Periodontal surgery within the previous 6 months
• Ongoing treatment with antibiotics and/or anti- inflammatory drugs past 3 months
• Ongoing treatment for tooth hypersensitivity
• Pregnancy or lactation
• Smokers