Chapter 44 Dental Liners, Bases and Bonding Systems Copyright 2003, Elsevier Science (USA). All rights reserved. No part of this product may be reproduced or transmitted in any form or by any means, electronic or mechanical, including input into or storage in any information system, without permission in writing from the publisher. PowerPoint® presentation slides may be displayed and may be reproduced in print form for instructional purposes only, provided a proper copyright notice appears on the last page of each print-out. Produced in the United States of America ISBN 0-7216-9770-4

Introduction Dental liner, bases, and bonding systems are in a classification of dental materials that provide additional protection for the health and well-being of a tooth being restored.

Prepared Tooth Structures The design of the cavity preparation gives strength within the tooth and helps determine how the tooth will hold the restoration in place.

Pulpal Responses Types of stimulus Examples of stimulus Physical Thermal, electrical Mechanical Handpiece, traumatic occlusion Chemical Acid from dental materials Biologic Bacteria from saliva

Dental Liners Dental liners provide a thin barrier that protects the pulpal tissue from irritation caused by physical, mechanical, chemical and biologic element.

Calcium Hydroxide Indications for use Protects the pulp from chemical irritation by its sealing ability. Stimulates the production of reparative or secondary dentin. Compatible with all types of restorative materials.

Calcium Hydroxide-cont’d Application process Placed only on dentin. Placed directly over the deepest portion of the preparation.

Fig. 44-1 Location for placement of calcium hydroxide.

Varnishes Indications for use* Seal the dentinal tubules. Reduce leakage around a restoration. Act as a barrier to protect the tooth from highly acidic cements such as zinc phosphate. * This material is contraindicated in its use under composite resins and glass ionomer restorations.

Varnishes-cont’d 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.

Fig. 44-5 Location for placement of cavity varnish.

Dentin Sealer Indications for use Treat or prevent hypersensitivity. Used instead of a varnish. Seal the dentinal tubules. Ideal for use under all indirect restorations.

Dentin Sealer-cont’d Application Process Material used sparingly. Do not allow to contact soft tissues (HEMA and glutaraldehyde). Apply the dentin sealer with the cotton-tipped applicator. Apply over all areas of the exposed dentin.

Dental Bases Dental bases provide pulpal protection. Protective base: Protect the pulp before the restoration is placed. Insulating base: Protect the tooth from thermal shock. Sedative base: Soothe a pulp that has been damaged by decay or irritated by mechanical means.

Types of Base Materials Zinc oxide eugenol Zinc phosphate Polycarboxylate Glass ionomer

Fig. 44-8 Location for placement of a base.

Dental Bonding Dental bonding improves retention by creating a micromechanical retention between the tooth structure and the restoration.

Enamel Bonding Enamel bonding is placed directly onto the intact enamel surface. Examples of Enamel Bonding Sealants Bonded orthodontic brackets Resin‑bonded bridges Bonded veneers

Dentin Bonding Dentin bonding is placed on prepared dentin in order to bond. Smear layer Thin layer of debris “Nature's bandage”

Etching Systems Etching Systems remove the smear layer in preparation for bonding. Supplied as: Liquid/Gel Maleic acid Phosphoric acid

Clinical Application of the Etchant and Bonding Systems Etchant is applied to remove the smear layer. Plaque or debris is removed before the bonding process. Avoid overdrying etched teeth. Too much primer is better than too little. Bonding solution covers all surfaces. Contamination with saliva requires the entire procedure to be redone.   Allow time for bonding material to mature before completing the restoration.      

Table 44-2: Supplementary Dental Materials and their Application in Order of Use