Dental Materials Restorations, Luting and Pulp Therapy Introduction
Restorations : A restoration is a material which substitutes the missing tooth structure and restores the form and function of the tooth
Types of Restorations Temporary, intermediate and permanent Direct and indirect Esthetic and non-esthetic
Temporary Restorations when ? Time ? Treatment to the pulp Disadvantage: sensitivity microleakage zinc oxide eugenol ( ZOE )
Intermediate Restorations particularly used in pedodontics Conventional zinc-eugenol cements are deficient in toughness. They have inadequate strength and abrasion resistance . As a result, polymer reinforced cement (IRM) is used.
Requirements of a Temporary Filling Material 1. Should have adequate strength to last a few weeks, but weak enough to be dislodged easily. 2. Should be easy to insert and remove. 3. Should have adequate seal. 4.Should have antibacterial properties. 5. Should have a beneficial effect (pain relief, healing, etc.) on the pulp. 6. Should have cariostatic properties.
Permanent Restoration any material that is expected to last much longer than the temporary and intermediate restorations. Ex.: direct filling gold, amalgam , composite resins, glass ionomer cement, silicate cement , as well as porcelain, composite and cast metal inlays and onlays.
The length of time : Amalgam --------- composite
Direct and Indirect Restorations
Esthetic and Nonesthetic An esthetic material is obviously something which is pleasing to an individual. Gold !! - Today an esthetic material implies any material that is capable of reproducing the color and appearance of a natural tooth.
LUTING ( Cementation ) Cementation is the process by which crowns, restorations and other devices are fixed or attached to tooth structure using an intermediate material called cement. Types Temporary cementation Permanent cementation
Temporary Cementation -Temporary bridges - should have some soothing effect on the pulp of the freshly prepared vital tooth An example of such a temporary bonding cement is a zinc oxide eugenol based cement
Permanent Cementation a) strong b) insoluble in oral fluids. c) be advantageous if it had some chemical bonding to the tooth structure. d) It should be fluid enough to flow . Ex. zinc phosphate cement, glass ionomer cement, resin cement, polycarboxylate cement
PULP CAPPING Pulp capping is a process of placing a specialized agent in contact with or in close proximity to the pulp with the intention of encouraging formation of new dentin (secondary dentin) and promote the healing of the pulp.
Criteria for Pulp Capping The pulp should be healthy and uninfected. The area of exposure should be no more than 0.5 mm. Following exposure the dentist should make all attempts to immediately isolate the tooth and prevent contamination.
Types of Pulp Capping : 1) Direct pulp capping 2) Indirect pulp capping
Such a situation is often encountered during : Direct Pulp Capping Such a situation is often encountered during : deep carious lesions Traumatic fractures of the tooth Iatrogenic exposure during cavity preparation Iatrogenic exposure during crown preparation.
Indirect Pulp Capping Secondary dentin formation can be induced even when the pulp is not exposed but is near exposure. When the calcium hydroxide is placed in the region of the near exposure, it can still induce new dentin formation through the remaining thin dentinal wall.
Indications of indirect pulp capping : Deep carious lesions close to the pulp. During excessive crown preparation the pulp is often visible through the remaining dentin as a pinkish or reddish spot or area. Similar near exposures may be seen in cases of traumatic tooth fracture.
CEMENT BASE is a layer of cement placed beneath a permanent restoration to encourage recovery of the injured pulp and to protect it against numerous types of insults . The type of insults depends upon the particular restorative material. It may be thermal or chemical. The base serves as replacement or substitute for the protective dentin, that has been destroyed by caries or cavity preparation
A) High Strength Bases :These are used to provide thermal protection & mechanical support for the restoration. Ex.: zinc phosphate, zinc polycarboxylate, glass ionomer and reinforced ZOE cements. B) Low Strength Bases : have minimum strength and low rigidity. Their main function is to act as a barrier to irritating chemicals and to provide therapeutic benefit to the pulp. Ex: calcium hydroxide and zinc oxide eugenol.
Properties of Dental Cements Thermal Properties : important sp. When metallic R. Is used. - Thickness at least 0.75 mm
Protection Against Chemical Insults Serve as barrier Calcium hydroxide and zinc oxide-eugenol are most effective for this especially in deep (close to the pulp) cavities. Polycarboxylate and glass ionomer bases are also used as chemical barriers in more moderate cavities
Therapeutic Effect Some bases are used for their therapeutic benefit to the pulp. For example, calcium hydroxide acts as a pulp capping agent and promotes the formation of secondary dentin. Zinc oxide-eugenol has an sedative effect on the pulp.
Strength : the cement base should develop sufficient strength rapidly, in order to allow early condensation of amalgam. The minimum strength requirement of a base between 0.5 and 1.2 mPa.
The cement base must have sufficient strength to: Withstand the forces of condensation . Withstand fracture or distortion under masticatory stresses .
The base is selected according to: 1)Design of the cavity 2) Type of permanent restorative material used. 3) Proximity of the pulp to the cavity walls .
Cavity Liner Is a dentine sealer that is less than 0.5 mm thick and is able to promote the health of the pulp by adhesion to the tooth structure or by antibacterial action .
Liners And Varnish Liners and varnishes are agents in a volatile solvent which when applied to a surface evaporates leaving behind a thin film. This film acts as a barrier which has different functions depending on the circumstance and the location where it is applied