Giomer-based varnish is a light-curable varnish/desensitizer. The surface pre-reacted glass (S-PRG) filler is a bioactive trilaminar structure with a multifunctional glass core embedded in resin matrix. It can release and recharge fluoride ions. When it becomes in contact with the oral fluids, it starts to bind to the collagen fiber and release six different types of ions like fluoride, calcium, phosphate that help in the formation of apatite crystals and seal the open dentinal tubules with a long-lasting effect Brand name: S_PRG (Shofu-Japan)

Bioactive glass powder delivered by an air-polishing device (ProJet 1) equipped with a 0.6-mm-diameter nozzle and a particle size range: 38-90 µm . A bioactive material that reacts with saliva to deposit Hydroxycarbonate Apatite crystals (HCA), which is very strong and resilient. The continuous release of calcium ions promotes constant protection and long lasting seal of the tubules. Using the air polishing delivery system helps to provide a huge amount of calcium and phosphate particles at the exposed surface of the tooth. Moreover, the air pressure aids in pushing these particles inside the dentinal tubules to a considerable depth. Air polishing using such powder provides a bifunctional advantage of occluding the dentinal tubules. However, there is limited clinical trials testing the efficacy of the bioactive glass powder air polishing system in minimizing the dentin hypersensitivity

Giomer varnish (PRG barrier coat) will used as the intervention agent in this study. , Giomer is considered as a hybrid material between the resins modified glass ionomers and the composite resins. It is composed of 45% Sio2, 24.5% Na2O, 24.5% Ca O and 6% P2O5

. The presence of sodium is very important due to its bioactivity while the phosphate is responsible for the degree of degradation and formation of apatite. Based on this composition, giomer has several clinical applications in implant, periodontics, bone generation, pulp capping, Root canal treatment, as restorative materials, in air abrasion, enamel remineralization and finally dentin hypersensitivity

Dentin hypersensitivity was assessed by three different stimuli (evaporative , thermal and tactile) to simulate the different situations in which Dentin hypersensitivity arises. Using the Visual Analog scale (VAS), the participant marks the pain intensity on a graduated 10 cm straight line (0

= no pain, 10 = extreme pain)

According to the Modified USPH criteria Alpha: Matches tooth Bravo: Acceptable mismatch Charlie: Unacceptable mismatch