1. Basing materials (materials used to protect pulp): role, classification, indications.

2. Objectives: Cavity preparation is relationship with pulp
Explain the protecting the pulp with cavity
Describe the purpose of using cavity liners, list the type of materials that can be used and explain the placement procedure
Describe the purpose of using cement base. List types of materials and placement procedure

3. Introduction:
Should be familiar preparation of the cavity with the amount of enamel and dentin removed and how near the preparation is to the pulp
Should understand the pulp protection theory that the depth of cavity preparations and pulpal relation

4. Cavity preparation/Pulp protection theory
The cavity preparation for a restoration depends on the amount of decay, the location of the decay, and the type of materials used to restore the tooth
Should examine the cavity preparation to assess pulpal involvement and then place the liners, base, or warnish

5. Treatment of cavity preparations
Treatment of the ideal cavity preparation
Treatment of the beyond – ideal cavity
preparation
3. Treatment of the near – exposure cavity preparation

6. Treatment of the ideal cavity preparation:
A base is not required because only a minimal amount of enamel and dentin has been removed
Some dentists place only the restoration, while other prefer to place a fluoride –releasing liner
If an amalgam restoration is going to be placed, two thin layers of cavity varnish are often placed over the dentin
If a composite restoration is going to be used, a glass ionomer liner or calcium hydroxide is placed over the exposed dentin

7. Treatment of the beyond – ideal cavity preparation
With a beyond –ideal preparation , the level of the dentin is restored with a cement base
With an amalgam restoration, there are several options. One option is to placetwo thin layers of varnish to seal the dentin tubules and then place a layer of a cement base, such as zinc phosphate

8. Another option is a reinforced ZOE base which has a soothing effect on the pulp. Varnish is not used with this material
Other options include polycarboxylate or glass ionomer base, which also do not require varnish
Under composite restorative materials, use a glass ionomer base or calcium hydroxide

9. Treatment of the near – exposure cavity preparation:
The nearer the cavity preparation comes to the pulp, the more precautions are needed. There are also several options of treatment of the near-exposure preparation
Cavity which going to restore with amalgam, a liner of calcium hydroxide , glass ionomer , or ZOE is placed first , then a layer of cement base such as Zinc phosphate, polycarboxylate, or glass ionomer cements

10. Another option for amalgam restoration is to place a liner, then a layer of reinforced ZOE, polycarboxylate, or glass ionomer cement. This is then sealed with cavity varnish , although some dentist do not place cavity varnish
Restore with composite, a liner is placed first, then place a layer of either polycarboxylate or glass ionomer cement
A cavity liner is placed on a near exposure, the procedure is often referred to as an indirect pulp capping

11. Treatment of the exposed- pulp cavity preparation:
In an exposed pulp, should be decided whether endodontic treatment is indicated or should save the vitality of the tooth.
If the treatment of choice is to save the pulp, a procedure called a direct pulp capping is performed

12. Cavity liners
Cavity liners are placed in the deepest portion of the cavity preparation on the axial walls or pulpal walls
When the liners are hardened, they form as a cement layer with minimum strength
Liners are protect the pulp from chemical irritations and also provide a therapeutic effect to the tooth
Liners are calcium hydroxide, zinc oxide eugenol, and glass ionomer cement
Liners also called low-strength base

13. On this direct pulp capping treatment, place the calcium hydroxide or glass ionomer liner and then reinforced ZOE as a temporary restoration . This gives to the dentist time to see whether the pulp is going to heal
Another treatment involves the placement of a liner, a layer of ZOE cement, two thin layers of varnish, and cement base
Some dentist prefer to place a liner and then a layer of polycarboxylate or glass ionomer cement base

14. Placement of cavity liner in preparation

15. Cavity varnish
Cavity varnish is used to seal the dentine tubules to protect acids, saliva and debris from the pulp
It is used under amalgam restorations to prevent microleakageand under zinc phosphate cement to prevent penetration of acid to the pulp
If cavity liners or medicated based are used,varnish is placed after or on top of these materials

16. Placement of cavity varnish

17. Cement bases
Cement bases are mixed to a thick putty and placed in the cavity to protect the pulp and provide mechanical support for the restoration
These cement bases are placed on the floor of the cavity
Cement bases are glass ionomers, hybrid ionomers, reinforced zinc oxide

18. Placement of cement bases