http:// www.dent.unc.edu/ portfolios/ bayne/ dental-materials/ VARNISH, LINERS, and BASES Stephen C. Bayne DENT112 Conservative Operative Dentistry School of Dentistry University of North Carolina Roberson TM. Sturdevant's Art and Science of Operative Dentistry, 4:170-177. http:// www.dent.unc.edu/ portfolios/ bayne/ dental-materials/ 2006, Bayne and Thompson
OVERVIEW OF PULPAL PROTECTION PROBLEM = No perfect replacement for missing enamel and dentin. NORMAL RESTORED CHEMICAL Protection PULPAL Medication THERMAL / ELECT Protection MECHANICAL Protection SOLUTION LINER = thin film (varnish, bonding system, dentin sealer) Suspension Liner (20-25 mm) CEMENT LINER = medium thickness (100-500 mm) CEMENT BASE = thick (500-1000 mm)
FLUID FLOW = J = (P) (r4) / (8) (h) (l) PULPAL PROBLEMS: Fluid Flow Microleakage Occlusion of tubules
CHEMICAL PROTECTION DEFINITIONS: Varnish = thin film solution liner (hydrophobic) Suspension liner = thin film aqueous liner (hydrophilic) Bonding system = thin film solution liner (hydrophilic) Dentin sealer = thin film solution liner (hydrophilic) Copalite Smear Layer on Dentin COPALITE = 90% solvent + 10% copal resin Hydrophobic and does not wet dentin well. Requires 2 applications for 85% coverage. Thin coats work best.
(Biological Protection) PULPAL MEDICATION (Biological Protection) PULPAL PROBLEMS: Fluid Flow Microleakage DENTIN FUNCTIONS: Chemical Protection Thermal / Electrical Protection Biological Protection (Medication) Mechanical Protection RDT 1º Dentin 2º Dentin 3º Dentin
(Biological Protection with Eugenol or Calcium Hydroxide) PULPAL MEDICATION (Biological Protection with Eugenol or Calcium Hydroxide) PULPAL PROBLEMS: Fluid Flow Microleakage DENTIN FUNCTIONS: Chemical Protection Thermal / Electrical Protection Biological Protection (Medication) Mechanical Protection pH = 11.0 Low strength Ca ion + salicylate and ZnO ( Zn++) Eugenol Palliative Ca(OH)2 Stimulating
THERMAL PROTECTION Intraoral HEAT FLOW: Normal thermal transient = 30-60s at 5-60°C HEAT paths = through restoration or via microleakage Pulpal temperature = f ( TIME, TEMP, THICKNESS ) RDT Through restoration: Thermal Conductivity Thermal Diffusivity Around restoration: Thermal Expansion
MECHANICAL PROTECTION PROTECTION = 1-2 mm (1000-2000 mm) > Chemical Protection (Sealed tubules) > Biological Protection (Pulpal Medication) > Thermal / Electrical Protection (1-2 mm) > Mechanical Protection (BASE = 1-2 mm) RMGI Polycarboxylate Zinc Phosphate
BASES
of Varnishes, Liners, and Bases COMMERCIAL EXAMPLES of Varnishes, Liners, and Bases
for Medicament, Liner/Base, Varnish/Sealer/DBS PROCEDURE SUMMARY for Medicament, Liner/Base, Varnish/Sealer/DBS RDT =