CHAPTER 2 BASES, LINERS, AND CEMENTS

Type I: Luting agent

Type II: Restorative

Type III: Base/liner

Type IV: Core material

Direct Pulp Capping

Factors influence the prognosis of direct pulp capping procedures

            Diminished with carious exposure

            Bacterial contamination

            Size of exposure

            Tooth development

            Treatment planning considerations

                        best prognosis with asymptomatic teeth either traumatically or mechanically exposed

Use of liners with amalgam restorations

                        Less than 0.5mm from the pulp:       

                                    Use Ca(OH)₂ followed by a fluoride-release liner (GIC) and a dentin bond

                                                agent/resin liner

                        Greater than 0.5mm from the pulp (low caries activity):

                                    Use a fluoride release liner (GIC) with or without a copal varnish or a dentin bond

                                                agent/resin liner

                        Greater than 0.5mm from the pulp (high caries activity):

                             Use a fluoride release glass ionomer liner (Vitrebond, XR Ionomer, Timeline,GIC etc.) and

                                         a dentin bond agent/resin liner

Clinical recommendations for using Bases and Liners

Do not base up to ideal form, as base weakens the restoration

Avoid covering the entire pulpal floor with a base/liner for a stress bearing restoration (Amalgam)

Glass ionomers can reduce post-op sensitivity better that zinc phosphate

Underneath resins

if less than .5 mm away from pulp, (seeing pink), use Dycal + a fluoride release liner + DBA

low caries rate, > 0.5 mm away from pulp: use a fluoride release glass ionomer liner or a DBA

high caries rate, > 0.5 mm away from pulp: use a fluoride release liner and a DBA

Under amalgams

pink < 0.5 mm from pulp - Dycal  + Vitrebond  + a DBA/resin liner

low risk >0.5 mm away from pulp - Vitrebond w or w/o copal varnish or a DBA/resin liner

high risk, > 0.5 mm away from pulp - Vitrebond + DBA/resin liner

Sandwich technique for Class V restorations

            A technique used to prevent class V resin failure at the gingival margin due to open margins from

                        polymerization shrinkage, which breaks the bond to dentin

     Glass ionomer is used because of its fluoride release mechanism

          thermal expansion/contraction is close to tooth structure

          chemical adhesion to enamel and dentin

          biologically compatible

           

            -place groove at 1/2 gingival wall with 1/4 or 33 1/2 bur

            -remove  smear layer with polyacrylic acid or ADA approved substitute (delete this step for Vitrabond)

            -place GI liner over exposed dentin

            -bevel occlusal enamel (1 mm)

                  acid etch enamel margin and glass ionomer liner for  20 seconds; a minimal amount of GI cement is lost during the etching process; a 15-30 second etch results in loss of 4 microns for “G-C liner” and 12-18 microns for Ketac Bond; rinse for 20 seconds. (Not necessary to etch Vitrabond liner)        

            -apply bond agent(s)

             -cure composite resin in two (2) increments; place the gingival increment first and cure for 60 seconds; add

            the incisal increment and cure for an additional 60 seconds