PowerPoint Presentation: - BHAVESH D. GABANI PULP PROTECTION: PULP PROTECTION The placement of liners and bases is not a step in tooth preparation, it is a step in adapting the preparation for receiving the final restorative material.: The placement of liners and bases is not a step in tooth preparation, it is a step in adapting the preparation for receiving the final restorative material. PULP PROTECTION-STEP:6 T he final cavity preparation stage VARIOUS TYPES OF IRRITANTS -Microbial irritation -Mechanical irritation -Thermal irritation -Chemical irritation -Radiant irritation - Bacteria that survive drying under the filling material remain viable for many years . Such dormant bacteria can become active when moisture is reintroduced as a result of -marginal percolation of various filling materials , -poor marginal seals improper condensation of fillings etc. : - Bacteria that survive drying under the filling material remain viable for many years . Such dormant bacteria can become active when moisture is reintroduced as a result of -marginal percolation of various filling materials , -poor marginal seals improper condensation of fillings etc. It depends on - Speed of rotation - Size & Shape of bur - Amount of moisture / water - Coolant : It depends on - Speed of rotation - Size & Shape of bur - Amount of moisture / water - Coolant MECHANICAL AND THERMAL IRRITATION Amount of moisture / water Speed of rotation - Size & Shape of bur - Various filling materials - Various medicaments used for desensitization or dehydration of dentin - Dentin sterilizing agents such as phenol, silver nitrate, eugenol etc. : - Various filling materials - Various medicaments used for desensitization or dehydration of dentin - Dentin sterilizing agents such as phenol, silver nitrate, eugenol etc. CHEMICAL IRRITANTS Dentin desensitization dehydration of dentin dentin sterilizing agents PowerPoint Presentation: To protect the pulp against those irritants we give - chemical protection - electrical protection - thermal protection - mechanical protection - pulp medication pulp we give - Pulp capping - Pulpotomy PULP PROTECTION In case of exposure of Chemical protection Electrical protection mechanical protection pulp medication thermal protection PULP Dental amalgam liners: liners - It is used to provide a barrier against the passage of irritants from cements or other restorative material and to reduce the sensitivity of freshly cut dentin. - They are usually suspensions of calcium hydroxide in a volatile solvents. - Liners are materials that are placed as a thin coating (usually 0.5 mm) on the surface of a cavity preparation. Examples: varnishes,l calcium hydroxide , Type glass ionomers,and resins Zinc eugenol , zinc phosphate, and zinc polycarboxylates are generally not used as liners . lv ZOE INDICATIONS: INDICATIONS - If the removal of infected dentin doesn’t extend deeper than 1 to 2 mm from initial prepared pulpal axial wall,usually no liner is indicated. - If the excavation extends into or close to the pulpal tissue,a calcium hydroxide liner is selected to stimulate reparative dentine. Iatrogenic pulpal exposure PowerPoint Presentation: - For composite restorations RMGI is mostly used. - a liner of calcium hydroxide is indicated only when pulpal exposure or the excavation is judged to be within 0.5mm of the pulp. Deep cavity preparation (less than 0.5mmthickness of dentin FUNCTION: FUNCTION Provide barrier that protects the dentin from noxious agents either from the restorative material or oral fluids. Intial electrical insulation. Some themal protection. RMGI under a class-1 composite to serve as a stress breaker. BASES: BASES A Base is a layer of cement placed beneath the permanent restoration to encourage recovery of the injured pulp and to protect it against numerous types of insults to which it may be subjected. The insults may be thermal or chemical or galvanic. PULP PROTECTION SMEAR LAYER TYPES: TYPES HIGH STRENGTH BASES Provide thermal protection for pulp & mechanical support for the restoration . Eg : Zn phosphate , Zn poly carboxylate , Glass ionomer , Resin modified glass ionomer cement(RMGI). 2. LOW STRENGTH BASES Have min strength & rigidity Act as a barrier to irritating chemicals and to provide therapeutic effect to pulp. Eg : Ca Hydroxide, ZnOE In case of deep excavation its necessary to overlay CaOH with RMGI or a srong base. GLASS IONOMER cement AND RESIN : GLASS IONOMER cement AND RESIN Usully glass ionomer is used for most “ base ” needs. These material effectively bond to tooth structure ,contain fluoride ,and have sufficient stength as a base. Because of their chemical and microchemical bond to tooth structure,retentive preparation features are not required. These material are excellent for bases under amalgam, gold, or ceramic restorations. Examples: Ketac -Silver (3M ESPE) and Fuji II LC Core Material (GC America). Paracore ( Coltene / Whaledent ) and Luxacore (Zenith/DMG) are examples of resin products. ZINC OXIDE EUGENOL: ZINC OXIDE EUGENOL Zinc oxide eugenol (ZOE) (example: Intermediate Re- storative Material, DENTS-PLY Caulk) materials provide an excellent seal of the cavity preparation . The ability of ZOE to reduce postoperative sensitivity is most likely due to disadvantage of this material is its inability to withstand the forces of condensation immediately after placement . The clinician should allow approximately 24 hours to pass prior to placing amalgam above a ZOE base . ZINC PHOSPHATE CEMENT: ZINC PHOSPHATE CEMENT The acidity is high at the time of insertion dueto phosphoric acid. As time passes acidity reduses,after one week it may rise to 6.9(=nuetral:7.0). A thickness of dentin as great as 1.5mm can be penetrated by the acid of the cement.if dentin is not protected against inflitration of this acid, pulpal injury may occur, especially during the first few hours. So, avoid thin mixes and pulp protection should be carried out in deep cavities through the use of an intervening liner or base like ZOE, calcium hydroxide, cavity varnish. CAVITY VARNISH: CAVITY VARNISH A varnish is defined as natural gum (copal or resin) dissolved in an organic solvent such as acetone, chloroform, or ether. After the dentin in the cavity preparation is covered with a varnish, the solvent evaporates, leaving the solute as a thin layer or film. The theory behind a varnish (example: Copalite /Cooley & Cooley) is that it seals the dentinal tubules, thus reducing the effects of micro-leakage . When amalgam is first placed, the tooth/amalgam interface is not microscopically sealed. Eventually the varnish dissolves and is replaced with the corrosion products of the amalgam.