1. Dr. Gaurav Garg Lecturer,M.D.S College of Dentistry, Zulfi, M.U.
19/2/2015
PULP PROTECTION –Liners & Bases
Dr. Gaurav Garg Lecturer,M.D.S College of Dentistry, Zulfi, M.U.

2. Intended Learning Objectives By the end of the lecture,
the student should be able to :
Recognize the importance of pulp protection
Classify different types of pulp protecting materials
Discuss about cavity varnish, cavity liners ,bases regarding definition,& composition, types,indications & contraindications and disadvantages
To recognize the importance of pulp medication and pulp capping in case of exposure of pulp
Analyze the criteria to select the procedure and appropriate liners, bases for different restorative materials

3. Introduction:
Dental pulp is subjected to various types of injuries before, during,& after restoration of carious tooth.
Irritants are caries, cavity preparation procedures, restorative materials used, leakage & recurrent caries

4. Need for Pulp Protection
Pulp needs protection against various irritants as following
Thermal protection against temperature changes
Electrical protection against galvanic currents
Mechanical protection during various restorative procedures
Chemical protection from potentially irritable components of restorative material
Protection from microleakage at interface between tooth and the restoration

5. Need of pulp protection from various irritants

6. Objectives of pulp protection:
To prevent further irritation of Pulp-Dentin organ and improve the defensive and reparative capabilities of P-D organ
To serve as a barrier against thermal changes, chemical irritants from within the restorative material and against leakage of bacterial by products

7. Basic functions of pulp protecting materials
Insulate the pulp
Protect the pulp in case of deep carious lesion
Act as barriers to microleakage and chemical irritants from restoration
Prevent bacteria and its toxins from affecting the pulp

8. Ideal requirements of pulp protecting agents
Biologically compatible with p-d organ
Chemically compatible with both p-d organ and the restoration
Should be capable of forming a non-permeable layer on cut dentin with thickness not affecting the bulk of restoration or its mechanical properties
The material should not discolor either the restoration or the tooth

9. Should set/harden quick enough to allow subsequent insertion of restorative material
Low solubility in saliva
Should withstand the condensation forces involved in the placement of overlying restoration
Stabilize and further decrease dentin permeability
Easy to use and manipulate during mixing and insertion.

10. Classification of pulp protecting materials
1. Cavity Sealers
i) Cavity varnish
ii) Adhesive sealer
2. Cavity liners.
3. Sub-Bases.
4. Cement Bases.

11. CAVITY VARNISH Definition: .
Cavity varnish is a solution of one or more resins which when applied onto the cavity walls , evaporates leaving a thin resin film, that serves as a barrier between the restoration and the dentinal tubules

12. Composition:
Natural gum such as copal, rosin, or synthetic resin (10%) dissolved in an organic solvent such as alcohol, acetone or ether (90%)
The copal rosin is dissolved in the ether, when the ether evaporates, a thin film of resin is left on the surface of the cavity.

13. Uses : 2. It minimizes the Marginal Leakage around the restoration
1. As a barrier against Chemical irritants
By preventing the penetration of acid from the restorative material.
By preventing the penetration of Corrosion products from amalgam restoration.
2. It minimizes the Marginal Leakage around the restoration
3. As a barrier against biological irritants (bacteria)

14. Disadvantages
Not an effective Thermal Insulator even with 2-3 coatings.
Very Sticky in nature.
Water soluble.

15. Indications for cavity varnish:
Below amalgam restoration – apply varnish to all the cavity walls, pulpal floor & to the margins.
Below Zinc Phosphate Cement- apply varnish to the pulpal floor, to prevent the acid penetration.

16. Contra-Indications: 1.Composite Resin:
Cavity varnish is contra indicated under composite resin restoration because
The solvent in the varnish will react with resin & soften the resin
Adhesive property is lost.
2. Glass Ionomer Cement:
Varnish interferes with chemical adhesion property of the GIC

17. METHOD OF APPLICATION:
Applied by using a disposable brush tips or a small pledget of cotton.
It should be applied in2-3 coats
Thickness:
The film thickness is 5-10 microns

18. DENTIN (ADHESIVE) SEALER
Recently dentin bonding agents have been used to seal dentin tubules in place of cavity varnish.
Indications for use
Treat or prevent hypersensitivity.
Used instead of a varnish.
Seal the dentinal tubules.
Ideal for use under all indirect restorations.

19. CAVITY LINERS Definition:
Cavity liners are agents which are used as protective coatings on the freshly cut cavities & in addition they have therapeutic action on pulp.
Also called Suspension Liner

20. Composition The basic components of the cavity liners are :
Therapeutic agent ( CaOH , ZOE, F) – which is dispersed or suspended in:
Resin solution , which acts as a carrier, the solvent evaporates leaving a layer of Calcium hydroxide or ZOE , on the cavity surface.

21. USE OF LINERS
To protect pulp from chemical irritants by sealing ability
It is used to provide a barrier against the passage of irritants from cements or other restorative material and to reduce the sensitivity of freshly cut dentin.
To stimulate formation of reparative dentin

22. Application of cavity liner
Is same as that of applying varnish
NOTE: It is mandatory to remove the liners from margins /walls of the cavity , as calcium hydroxide dissolves in the oral fluids & is not effective against micro-leakage.
The thickness of the liner is 0.5mm.

23. Types of cavity liners Calcium Hydroxide based. ZOE based. GIC Liners.
Flowable composites

24. Calcium hydroxide has been used as liner in deep preparations because of its following features:

25. Limitations of Calcium hydroxide liners
Low strength
High solubility
when it is exposed to the oral environment (e.g. due to leakage) it dissolves. This limits its use over only small areas requiring pulp protection.

26. ZOE liners
ZOE liners are contra-indicated below composite resin restoration, as it interferes with polymerization.

27. Glass ionomer liners
The modified GIC in the form of Resin modified ( RMGIC) is commonly used because of its
Advantages :
- Chemical adhesion.
- Good mechanical strength.
- Fluoride Release.
- Well controlled setting time.
- Rapid achievement of strength.

28. Flowable composites as liners
Flowable composites are the composites with a lower amount of filler.
This reduced filler content allows more fluid consistency, less strength and less stiffness than fully filled composites

29. Advantages of flowable composite liners
Adaptation to preparation walls because of their flow
Easy to place since the materials are injected directly into the preparation
Esthetic
Consistency

31. SUB-BASES
Therapeutic materials placed in deep portion of the cavity preparation.
They have specific pharmacological action.
They should be covered with supporting base as they have low strength.

32. Calcium Hydroxide is most commonly used as Sub-Base.

33. Properties: It has very low mechanical properties.
It has low compressive Strength, hence can not with stand condensation forces.
It stimulates the formation of reparative dentin, because of its alkaline Ph (11.7)

34. USES OF CALCIUM HYDROXIDE
It can be used as cavity liner or sub – base or low strength base .
Material of choice for pulp capping.
In extremely deep areas as an anti bacterial agent.
It can be used with composite resin as it does not interfere with the polymerization.

35. CEMENT BASES Definition:
Layer of cement that is placed under the permanent restoration to protect the pulp against numerous types of irritation is called Base.
The irritation could be thermal, mechanical & Chemical irritation.

36. Base is a replacement for protective dentin, which is been destroyed during caries process or during cavity preparation or both.
The thickness of Base is typically mm.

37. CLASSIFICATION HIGH STRENGTH BASES Zinc Phosphate Cement.
Zinc oxide Eugenol (Modified-TYPE III)
Zinc poly carboxylate cement.
Glass ionomer cement.
Resin modified GIC (highest strength Mpa)

38. LOW STRENGTH BASES CALCIUM HYDROXIDE(SELF CURE)
CALCIUM HYDROXIDE(LIGHT CURE)
ZINC OXIDE EUGENOL(TYPE IV)

39. Uses of base: As a chemical insulator.
As a Thermal insulator (minimum thickness- 0.75).
As a Mechanical support for the restoration by distributing stresses to the underlying dentin.
The cements used as base should have sufficient strength to withstand the forces of condensation so that the base is not fractured during insertion of the restoration.

40. CLINICAL CONSIDERATIONS

41. The clinical judgment for the use of specific PULP PROTECTION material depends on following factors:-
FACTORS
--Remaining dentin Thickness (RDT)
- Design of the cavity.
- Adhesive property of the material.
- Proximity of the pulp to the cavity floor
- Type of restorative material used.

42. Restorative material
Shallow cavity
( RDT=2mm or more)
Moderately Deep cavity
( RDT=0.5-2mm)
Deep cavity (RDT=0.5mm or less)
Amalgam
Only sealer (varnish)
Base+ Sealer
Liner/sub base + base + sealer
Composite
Nothing (restore directly)
Resin modified GIC base
Calcium hydroxide liner/sub base+ Resin modified GIC base
For composites Cavity varnish, ZOE formulated liners & ZOE base materials are contra-indicated as it interferes with polymerization.
GIC is the preferred base material for composite (best resin modified GIC)

43. Varnish/sealer should be applied on all walls & floors of the cavity
Bases/Sub-bases/Liners should be applied only on Pulpal floor & Axial wall (in case of class II cavity)
Never apply base/sub-base/liner on other walls and Gingival floor (in case of class II cavity)

44. References & Suggested reading
Sturdevant's art & science of operative dentistry Theodore M. Roberson, Harald O. Heymann, Edward J. Swift, Jr.
Principles of operative dentistry (2005)- A.J.E. Qualtrough, J.D. Satterthwaite, L.A. Morrow and P.A. Brunton.
Fundamentals of Operative Dentistry- 2nd Edition- Summitt & Robbins