Operative Dentistry Course RSTD 1100
Lecture 17 Dr. N. Blight
Cavity Sealers, Liners & Bases
Cavity Sealers, Liners & Bases
Objectives: identify the functions of Bases, Liners & Sealers (Dentin Bonding Agents) specifically with regards to their r oles in Operative Dentistry To determine when to use these materials in the pr ocedures 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. To
Definition intermed mediary iary mat materials erials that may be Sea ealler ers, s, lin iner ers s an and d ba bas ses ar are e inter placed beneath definitiv ive e restorativ ive e materials (e.g. amalgam, composite resin, gold/porcelain inlays and onlays, etcetera) to pr otec ectt the pu pulp lp..
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 preparati ons to pr otect the pulp fr om 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: pr ovide a pr otective 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, pr otective 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 micr oorganisms along the interface between a restoration and the walls of a cavity preparation. (Mosby. Mosby's Dental Dictionary . Elsevier, 2004.).
Cavity Sealers 1. Varnishes : a natural r osin (copal-gum) dissolved in an organic solvent Capable of reducing the dentin permeability by 70% Studies have shown that copalite can reduce micr oleakage fr o 4-6 months. Used as a barrier against bacteria & their ass ociated toxins/by pr oducts fr om entering the dentinal tubules Disadvantage: no thermal insulation (ex. Copalite) - not used very often anymore! 2. Dentin Bonding Agents: adhesive system pr oviding sealing to the walls & floors of the cavity preparation. Most recent material to be used as a sealer
Bonding Agents Many pr oducts exist Went fr om 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 Agents Single or Uni-doses now available One time use Less contamination versus many time use bottles $$$$$$ Examples: S inglebond, Prime & Bond, Optibond, Permaquick
Varnish A natural gum (c opal or r osin) in an organic solvent (acetone, chlor of orm or ether) The solvent evaporates leaving a pr otective film on the cut tooth Seals the dentinal tubules Pr ovides a barrier to bacteria and oral fluids Thin film usually no more than 2-5 µm EXAMPLES: Copalite ®, Copaliner ® N ot
used often clinically!!!
Resin B onding 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 micr oleakage EXAMPLES: Amalgambond®, All-Bond®
Resin Bonding Agents Alloybond by SDI most common
is the
Ease of use Etch first, wash and dry, apply PRIMER first, then light cure BASE (one dr op) + CATALYST (one dr op) mixed together and applied to dentin AMALGAM is condensed immediately
Cavity Liners Dycal (Calcium Hydr oxide) Has been used as a liner f or a long time This is due to the pulpal compatibility & its ability t o stimulate the f ormation of reparative dentin Current studies have f ound that Calcium Hydr oxide (Dycal) does not primarily stimulate reparative dentin f ormation, but assists due to its antibacterial nature.
Liners Pr ovide 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 f ormation of reparative (or tertiary dentin) not bondable to tooth High solubility: results in contamination of resins, theref ore increased marginal leakage DyCal Pr oCal or
resin solution VLC Dycal
* Must be placed over the smallest area that would help reparative dentin f ormation 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 DyCal DyCal
Soluble Poor compressive strength 1,200 lbs/sq. in. Better Calcium release and pr oduction of tertiary dentin
VLC
DyCal
Less soluble Better compressive strength 18,000 lbs/sq. in. Less effective Calcium release and pr oduction of tertiary dentin
Cavity Liners
Qui
T FF
Ti i o
o i
o i ure.
FIG. 4-45 S emati examples of use of li ers and bases for amalgam restorations. A, For shallow amalgam tooth preparations, varnish or sealer is applied to walls of preparat ion before insertion of restoration. B, For moderate depth tooth preparations, liners may be placed for thermal pr otection and pulpal medication. (Note seats in sound dentin for amalgam restoration.) C, In ver y deep preparat ion, light-cured calcium hydr oxide is placed in deepest region in which inf ected 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 hydr oxide liner in the deepest region ( judged to be within 0.5 mm of pulp). (Roberson, Theodore Roberson. S turdevant's Art and S cience of Operative Dentistry, 4t h Edition.
Elsevier, 2002.).
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 f or bases Glass Ionomer Reinf orced ZOE Zinc Phosphate Polycarboxylate
Glass Ionomer Cements Close to ideal liner or base
Universal use EXCEPT f or direct pulp exposures or near exposures Acceptable c ompressive strength 12,500 lbs/sq. in. Releases fluoride Adhesive bond to dentin
Glass 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 Pr oblems: inhibits composite polymerization
Zinc Phosphate Cement zinc oxide powder aqueous sol¶n of phosphoric acid acidic pH irritating to the pulp Blamed f or 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 zinc oxide powder polyacrylic acid non-irritating to the pulp compressive strength of 8,000 lbs/sq. in. chemically bonds to tooth structure POLY DURELON
Cement
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 f or 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 #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 f or 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 ill 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 f ormation rigid minimum 10,000 p.s.i. acid insoluble chemical bond to dentin
fast setting bondable to composite, amalgam etc. free flowing anticariogenic ( luoride release) radiopaque
