LINERS AND BASES Department Of Conservative and Endodontics

LINERS AND BASES Department Of Conservative and Endodontics Dentistry Explorer

Contents • • • Liners Bases Cavity varnish Calcium hydroxide Conclusion References Dentistry Explorer

Many restorative dental materials that provide excellent properties for the bulk of a dental restoration may not protect the dental pulp during setting or during cyclic thermal or mechanical stressing. PULPAL PROTECTION Dentistry Explorer

CAVITY LINERS • Are relatively thin layers of material used primarily to provide a barrier to protect the dentin from residual reactants diffusing out of a restoration &/or from oral fluids that may penetrate leaky tooth-restoration interfaces. • Contribute initial electrical insulation. • Generate some thermal protection. • In some formulation, provide pulpal treatment as well. Dentistry Explorer

CAVITY LINERS…… Types : ØThin film liners : 1 -50 µm Ø(a) Solution liners (varnishes) : 2 -5 µm e. g. : Copalite (b) Suspension liners : 20 -25 µm e. g. : Pulpdent, Dycal ØThick liners : 0. 2 -1. 0 µm - primarily for pulpal medication & thermal protection. Dentistry Explorer

Location for placement of cavity liner Dentistry Explorer

Composition of Typical Liners Calcium hydroxide (VLC Dycal) Traditional GI (Fuji lining LC ) Reinforced ZOE (IRM) Paste (with Ca(OH)2 , LC resin, and polyphenolics) Powder ( Al-silicate glass); Liquid (polyalkenoate acid, LC resin) Paste (with Zn. O); Paste (with Eugenol) Dentistry Explorer

CAVITY VARNISH • Liner ingredients are dissolved in a volatile non aqueous solvent. • Rely on evaporation of solvent for hardening & produce thin film. • Are insoluble in oral fluids. Indications for use • Seal the dentinal tubules. • Reduce leakage around a restoration. This material is contraindicated in its use under composite resins and glass ionomer restorations Dentistry Explorer

Components : Solid 10% copal resin Solvent 90% ether, acetone, alcohol Application process � Applied with either a small disposable applicator or a cotton pellet. � Thin coating of the varnish on the walls, floor, and margin of the cavity preparation. � Apply a second coat. Dentistry Explorer

Location for placement of cavity varnish Dentistry Explorer

BASES • Are thicker protective layers of cement that are placed under restoration to : • Encourage recovery of injured pulp. • Protect it against thermal shock & chemical irritation. • Provide mechanical support for the restoration. - Typically 1 -2 µm Types • High strength base • Low strength base Dentistry Explorer

Selection of base depends on: – Design of cavity preparation. – Type of restorative material – Proximity of pulp in relation to cavity wall Principles of basing: • Apply base on pulpal & axial walls only. • Confine base to deepest part of the pulpal &/or axial walls. • Apply minimum thickness of base if possible. • Therapeutic bases should be covered with a stronger , more durable & compatible bases. Dentistry Explorer

Location for placement of Bases Dentistry Explorer

Ideal requirements • Capable of creating an impervious layer of cut vital dentin in a • • • minimum thickness. Biologically & chemically compatible with dentin/pulp & restorative material. Neither discolor tooth nor restoration. Set quickly to allow for subsequent insertion of restoration. should withstand condensation forces. Easily manipulated & insertion Dentistry Explorer

Composition of Typical Bases Zinc phosphate cement (Modern Tenacin) Polycarboxylate cement (Durelon) Glass ionomer cement (Ketac-cem) Resin modified glass ionomer cement (Vitremer) Zn. O powder H 3 PO 4 /H 2 O Zn. O powder Polyacrylic acid/H 2 O F-Al-Si glass powder Monomers/H 2 O Dentistry Explorer

ZINC OXIDE EUGENOL – – – – The oldest & most effective. One of the best insulator & sealer of dentinal tubules. Has least shrinkage of all bases. Has highest viscosity. Sedative & anti-inflammatory action on pulp & dentin. Hygroscopic action. Its sealing ability minimizes micro leakage. Insulates against thermal & galvanic shocks. Dentistry Explorer

ZINC PHOSPHATE BASE Highest compressive strength. Lowest viscosity. Least soluble & disintegration. Low film thickness. Self etching. Varnish should always precede it on cut dentin. Under direct gold restoration , cast restoration. Only a mechanical diffusion barrier & thermal insulator. • Best base for amalgam restoration. • • Dentistry Explorer

ZINC POLYCARBOXYLATE BASE • Can be used as base for preparation with effective depth as low as 0. 5 mm. • Only mechanical diffusion barrier & thermal insulator. • Solubility & disintegration : high. Dentistry Explorer

CALCIUM HYDROXIDE CEMENT A relatively weak cement. Available as : 1. two paste system 2. light cured system Composition Base paste: Glycol salicylate- 40% , calcium sulphate , titanium dioxode , barium sulphate. Catalyst paste: Ca(OH)2 , zinc oxide , zinc stearate , sulphonamide. Dentistry Explorer

• Setting reaction Ca(OH)2 reacts with salicylate ester to form a chelate. • Setting time: 2. 5 -5. 5 minutes. : Compressive strength -10 -27 Mpa after 24 hours. Tensile strength -1. 0 Mpa. Thermal property -good Solubility & disintegration – 0. 4 -7. 8% (most soluble). • Properties Dentistry Explorer

• Biologic Property : Effect on pulp : p. H 9. 2— 11. 7 Formation of tertiary dentin. • Light Activated Ca(OH)2 : -Consist of Ca(OH)2 & barium sulphate dispersed in a urethane dimethacrylate resin. - Also contains polymerization activators. Dentistry Explorer

Uses • • Cavity base Pulp capping agent Cavity liner Root canal sealing paste Dentistry Explorer

SUMMARY OF PULPAL PROTECTION PROCEDURES Restoration Shallow excavation (RDT>2 mm) Moderate excavation (RDT: 0. 5 -2 mm) Deep excavation (RDT : <0. 5 mm) -NO MEDICAMENT -NO LINER -ONLY VARNISH -NO MEDICAMENT -APPLY BASE -APPLY VARNISH -DYCAL LINER -POLY F BASE -VARNISH -NO MEDICAMENT -NO LINER -DENTIN BONING SYSTEM -NO MEDICAMENT -NO BASE -DENTIN BONING SYSTEM -DYCAL -NO BASE -DENTIN BONING SYSTEM Dentistry Explorer

Conclusion Liners, bases, cavity varnish, calcium hydroxide are materials that are used routinely in our practice. so their knowledge is essential for their successful application. Dentistry Explorer

REFERENCES • Sturdevant’s ART & SCRINCE OF OPERATIVE DENTISTRY; 5 thedition • OPERATIVE DENTISTRY- Modern Theory & Practice; M. A. Marzouk • PHILIPPS’ SCIENCE OF DENTAL MATERIALS ; Kenneth J. Anusavice; 11 th edition • BASIC DENTAL MATERIALS ; John J. Manappallil; 2 nd edition Dentistry Explorer

THANK YOU Dentistry Explorer