Operative DentistryCourse RSTD 1100Operative DentistryCourse RSTD 1100

Lecture 17

Dr. N. Blight

Cavity Sealers, Liners & Bases

Cavity Sealers, Liners & Bases

Objectives:Objectives:

• To identify the functions of Bases, Liners & Sealers (Dentin Bonding Agents) specifically with regards to their roles in Operative Dentistry

• To determine when to use these materials in the procedures of Operative Dentistry

• To discuss the physiological response of the various materials to the tooth

• To address specifically the importance liners, bases & sealers in terms of pulpal vitality & success of the definitive restoration.

Definition

• Sealers, liners and bases are intermediary materials that may be placed beneath definitive restorative materials (e.g. amalgam, composite resin, gold/porcelain inlays and onlays, etcetera) to protect the pulp.

Fundamentals of Operative Dentistry: A Contemporary Approach by Schwartz, R. S., Summitt, J. B. and Robbins, J. W. (1997).

Cavity Sealers, Liners & Bases

• applied to cavity preparations to protect the pulp from irritation or injury by

• caries• toxins• depth of preparation

• cavity preparation• heat• depth of preparation

• restorative material• metallic restoration (thermal shock)• acid-containing cement (chemical

irritation)• seal between tooth and restorative

material

Cavity Sealers/Dentin Bonding Agents

• Cavity sealers: provide a protective coating to the walls & floors of a prepared cavity as well as a barrier to leakage at the interface between the walls & the restorative material

• Thin, protective coating over freshly cut tooth structure• Purpose of a sealer: to provide a seamless transition from

the tooth to the restoration, thus preventing microleakage• What is Microleakage?

the seepage of fluids, debris, and microorganisms along the interface between a restoration and the walls of a cavity preparation.

(Mosby. Mosby's Dental Dictionary. Elsevier, 2004.).

<vbk:0-323-02510-2>

Cavity SealersCavity Sealers

1. Varnishes : a natural rosin (copal-gum) dissolved in an organic solvent

• Capable of reducing the dentin permeability by 70%• Studies have shown that copalite can reduce microleakage fro 4-6

months. • Used as a barrier against bacteria & their associated toxins/by

products from entering the dentinal tubules• Disadvantage: no thermal insulation• (ex. Copalite) - not used very often anymore!

2. Dentin Bonding Agents: adhesive system providing sealing to the walls & floors of the cavity preparation.

• Most recent material to be used as a sealer

Bonding AgentsBonding Agents

• Many products exist• Went from two-step to now

6th generation bonding systems only requiring one step

• Primary function is to seal the dentinal tubules, thus preventing post-operative sensitivity

• Remember: No etch technique required when using a bonding agent under amalgam restoration

Bonding AgentsBonding Agents

• Single or Uni-doses now available

• One time use• Less contamination

versus many time use bottles

• $$$$$$• Examples: Singlebond,

Prime & Bond, Optibond, Permaquick

VarnishVarnish

• A natural gum (copal or rosin) in an organic solvent (acetone, chloroform or ether)

• The solvent evaporates leaving a protective film on the cut tooth

• Seals the dentinal tubules• Provides a barrier to bacteria and oral

fluids• Thin film usually no more than 2-5 µm

EXAMPLES: Copalite ®, Copaliner ®

Not used often clinically!!!

Resin Bonding Agents

• Include dentin bonding systems and all-purpose bonding systems

• Serve the same functions as sealers/varnishes but have the additional benefit of bonding the restorative material to tooth structure, thereby strengthening the tooth & reducing microleakage

• EXAMPLES: Amalgambond®, All-Bond®

Resin Bonding AgentsResin Bonding Agents

• Alloybond by SDI is the most common

• Ease of use• Etch first, wash and dry,

apply PRIMER first, then light cure

• BASE (one drop) + CATALYST (one drop) mixed together and applied to dentin

• AMALGAM is condensed immediately

Cavity LinersCavity Liners

• Dycal (Calcium Hydroxide) Has been used as a liner for a long time

• This is due to the pulpal compatibility & its ability to stimulate the formation of reparative dentin

• Current studies have found that Calcium Hydroxide (Dycal) does not primarily stimulate reparative dentin formation, but assists due to its antibacterial nature.

LinersLiners

• Provide a barrier to irritants like sealers BUT ALSO have a THERAPEUTIC EFFECT such as

• Fluoride release (Glass Ionomer Cements)

• Antibacterial effect (Glass Ionomer Cements, Calcium Hydroxide)

• Stimulation of the formation of reparative dentin (Calcium Hydroxide)

• Adhesion to tooth structure (Resin Bonding Agents)

• Minimal thickness (less than 0.5 mm)

Calcium Hydroxide• accelerates formation of

reparative (or tertiary dentin) • not bondable to tooth• High solubility: results in

contamination of resins, therefore increased marginal leakage

• DyCal• ProCal

• or resin solution• VLC Dycal

* Must be placed over the smallest area that would help reparative dentin formation to occur when a pulp exposure is imminent or exists *

Calcium Hydroxide

INDICATIONS• Placed in a thin layer

near the pulp in deep preparations

• IPC (Indirect Pulp Cap)

OR • Direct Pulp Cap• Placed where dentin

thickness is less than 0.5-1.0 mm

CONTRA-INDICATIONS• Unnecessary in shallow

preparations • Unnecessary where

dentin thickness is greater than 1.0 mm

DyCal vs VLC DyCalDyCal vs VLC DyCal

DyCal• Soluble• Poor compressive

strength 1,200 lbs/sq. in.

• Better Calcium release and production of tertiary dentin

VLC DyCal• Less soluble• Better compressive

strength 18,000 lbs/sq. in.

• Less effective Calcium release and production of tertiary dentin

Cavity LinersCavity Liners

QuickTime™ and aTIFF (PackBits) decompressorare needed to see this picture.

FIG. 4-45 Schematic examples of use of liners and bases for amalgam restorations. A, For shallow amalgam tooth preparations, varnish or sealer is applied to walls of preparation before insertion of restoration. B, For moderate depth tooth preparations, liners may be placed for thermal protection and pulpal medication. (Note seats in sound dentin for amalgam restoration.) C, In very deep preparation, light-cured calcium hydroxide is placed in deepest region in which infected dentin was excavated, and then base of glass ionomer is inserted. Amalgam bonding systems are being advocated as a substitute for liner and varnish, except for calcium hydroxide liner in the deepest region (judged to be within 0.5 mm of pulp).

(Roberson, Theodore Roberson. Sturdevant's Art and Science of Operative Dentistry, 4th Edition. Elsevier, 2002.). <vbk:0-323-01087-3#F156>

Bases

• Defined as a dentin replacement material to • allow less bulk of the definitive restorative material (ex.

amalgam) OR

• block out undercuts for inlay or onlay preparations • - Why can there not be undercuts in an inlay

preparation????• Must possess adequate strength to support restoration• Thickness maximum less than 2.0 mm • Types of cements used for bases

• Glass Ionomer • Reinforced ZOE • Zinc Phosphate • Polycarboxylate

Glass Ionomer Cements

• Close to ideal liner or base• Universal use EXCEPT for direct pulp

exposures or near exposures• Acceptable compressive strength 12,500

lbs/sq. in.• Releases fluoride• Adhesive bond to dentin

Glass Ionomer CementsGlass Ionomer Cements

• Vitrebond• GC Lining Cement• Ketac-Cem

Reinforced ZOE

• IRM (Intermediary Restorative Material)

• Non-irritating to the pulp• Low compressive strength

8,000 lbs/sq. in.• Does not bond to tooth

structure• Excellent thermal insulation• Problems: inhibits

composite polymerization

Zinc Phosphate Cement

• zinc oxide powder• aqueous sol’n of phosphoric

acid• acidic pH• irritating to the pulp• Blamed for post-op

sensitivity• requires a varnish to seal the

dentinal tubules• compressive strength is

15,000 lbs/sq. in.• does not bond to tooth

structure• TENACIN• HY-BOND

Polycarboxylate CementPolycarboxylate Cement

• zinc oxide powder• polyacrylic acid• non-irritating to the pulp• compressive strength of

8,000 lbs/sq. in.• chemically bonds to

tooth structure • POLY F• DURELON

Minimum Basing Concept

• Since little or no pulp reaction occurs when there is 2.0 mm thickness of dentin over the pulp, a base is not necessary at all unless there is less than 2.0 mm of dentin thickness over the pulp

• The best possible base is SOUND tooth structure• Minimize the extent of the base as it can:

* lead to decreased bulk of restorative material

* increased potential for restoration fracture

Case #1

• classical cavity preparation

• >2 mm dentin thickness

Case #1

• place cavity sealer/bonding agent• Dentin bonding Agent

OR• Varnish

• Give 3 examples of dentin bonding agents.

Case #1

• fill with amalgam

• What would be the sequence if we used a composite resin?

• Can you use a varnish under a composite resin restoration?

Case #2

• cavity preparation slightly deeper than normal

• >2 mm dentin thickness

Case #2Case #2

• place cavity sealer/dentin bonding agent• Dentin Bonding Agent

OR• Varnish

Case #2

• fill with amalgam

• What would be the sequence if we use a composite resin?

Case #3

• deep cavity preparation• 1 mm dentin thickness

remaining over pulp horns

• What materials should you consider for this preparation?

Case #3

• Requires a base• What are your choices?

• Name 4 examples of bases that you could use

Case #3

• place cavity sealer/dentin bonding agent• Dentin bonding Agent

OR• Varnish

• What if we are placing a composite resin? What base can you NOT use with a composite resing?

Case #3

• fill with amalgam

Case #4

• deep cavity preparation • decalcified dentin

adjacent to the pulp• < .5 mm dentin

thickness over the pulp• pulp exposure imminent

if all caries removed at this time

Case #4

• Requires a liner• What are your choices?

• Is this a direct or indirect pulp cap????

• What is the clinical difference?

Case #4

• place a base • THICKNESS???

• Give 4 examples of bases you could use under an Amalgam restoration

Case #4

• place cavity sealer/dentin bonding agent• Dentin Bonding Agent

OR• Varnish

Case #4

• fill with amalgam• Fill with composite

Case #5

• small pulp exposure in deepest part of cavity preparation

Case #5

• Place a liner• What type of liner?• What thickness is

required?• Is this a direct or

indirect pulp cap?

Case #5

• Place a base. • WHY????• What type of base could

be used?• How thick should the

base be?

Case #5

• place cavity sealer/dentin bonding agent• varnish

OR• resin bonding agent

Case #5

• fill with amalgam

IDEAL PULP PROTECTIVE MATERIAL (R.E. Jordan)

• biologically compatible, non-irritating

• stimulates dentin bridge formation

• rigid

minimum 10,000 p.s.i.• acid insoluble• chemical bond to dentin

• fast setting• bondable to composite,

amalgam etc.• free flowing• anticariogenic (Fluoride

release)• radiopaque

Thank YouThank You