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

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

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

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

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

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

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

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

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

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

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

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

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

Placement of cavity liner in preparation

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

Placement of cavity varnish

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

Placement of cement bases