Dental Materials I- Ch 44/ TEST

Types of supplemental dental materials

Dental liners

Bases

Varnishes

Bonding systems

Prepared Tooth Structures

Design of the cavity preparation does the following:

Provides strength within the tooth

Helps determine how the tooth will hold the restoration in place

Pulpal Responses: Types of Stimuli

Physical stimuli

• Examples: Thermal, electrical

Mechanical stimuli

• Example: Handpiece, traumatic

Chemical stimuli

• Example: Acid from dental materials

Biologic stimuli

• Example: Bacteria from saliva

Cavity Liners

A thin layer of material placed at the deepest portion of the dental preparation to provide pulpal protection or dentinal regeneration

Protect pulpal tissue from irritation caused by physical, mechanical, chemical, and biologic elements

The health and condition of the tooth being restored determine what lining agent the dentist will select

Cavity Liners Examples: Calcium Hydroxide

A frequently selected type of cavity liner because of its unique characteristics

Protects the pulp from chemical irritation through its sealing ability

Stimulates the production of reparative or secondary dentin

Is compatible with all types of restorative materials

Cavity Liners Examples: Varnish

Liquid consisting of one or more resins in an organic solvent

Placed within the entire preparation

Application accomplishes the following:

Seals dentinal tubules

Reduces microleakage around a restoration

Acts as a barrier to protect the tooth from highly acidic cements such as zinc phosphate

Cavity Liners Examples: Fluoride Varnish

Gel-like substance designed to release fluoride on enamel, root structure, and dentin structure

Specific indications include:

Professional topical fluoride application

Treatment of hypersensitive cervical areas

Orthodontic patients

Cavity varnish

Dentin sealant

Cavity Liners Examples: desensitizer

Used to treat or prevent hypersensitivity that a patient may experience from a newly placed direct or indirect restoration (Also referred to as a primer)

Designed to seal the dentinal tubules

No surface layer of the preparation is prepared when a desensitizer is used (Ideal for use under all indirect restorations)

Application of Desensitizer

Most desensitizers contain hydroxyethyl methacrylate (HEMA) and glutaraldehyde

Used sparingly

Do not allow the material to contact soft tissue

Dental Bases

When a tooth preparation becomes moderately deep or deep, the dentist will place a base under the permanent restoration

• A base is an additional layer to protect the pulp

Bases provide different types of pulpal protection

• Protective: Protect the pulp from a large restoration

• Insulating: Protect the tooth from thermal shock

• Sedative: Soothe pulp that has been damaged by decay or irritated by mechanical means

Types of Base Materials

Zinc oxide–eugenol (ZOE)

• Could be selected for use as an insulating base and as a sedative base

• Cannot be used under composite resins, glass ionomers, or other resin restorations

Zinc phosphate

• Excellent material because of its thermal insulation qualities

Polycarboxylate

• Nonirritating to the pulp

Application of a Base

Base material resembles a putty-like consistency because it actually provides a buffer or layer between the pulp and the restoration

The entire pulpal floor is covered with a base to a thickness of 1 to 2 mm

Dental Etchant

In preparation for the use of a bonding material, the tooth surface will need to be etched with an acidic tooth conditioner

• When you rinse and dry an etched surface, it will have a distinct "frosted" appearance

Critical for both enamel and dentin surfaces of a cavity preparation to form a better mechanical bond between the tooth and the permanent restorative material

Application of Dental Etchant

Supplied either as a liquid or gel, with gel being packaged in a syringe-type applicator

Syringe dispensing through pre-bent dispenser needles provides precise placement of the material on tooth

15 to 20 seconds is the most common recommended time

Dental Bonding

The process of solid and/or liquid contact of one material with another at a single margin

Creation of micromechanical retention between the tooth structure and the restoration

A major factor in the success of bonding to dentin is the removal of the smear layer, which is a very thin layer of debris composed of fluids and tooth components that remain on dentin after cavity preparation has been completed

• A slight amount of moisture must be maintained on the dentin so as not to desiccate or “dry out” the tooth

• Before dentin bonding, the smear layer must be removed through application of etchant and the tubules opened

Enamel Bonding

Examples of enamel bonding include:

1. Sealants

2. Bonding of orthodontic brackets

3. Resin-bonded bridges

4. Resin-bonded veneers

When sealant, resin cement, or restorative material is placed on an etched surface, it flows in and around the enamel tags

The material hardens in this location to form a strong mechanical bond with enamel

Dentin Bonding

Dentin consists of organic substances

Bonding of restorative dental materials can be difficult

• Major factor in success of bonding a material to dentin is removal of smear layer

• Smear layer protects tooth by obliterating (to remove from existence) openings of dentinal tubules

Slight amount of moisture must be maintained on dentin

• If dentin is completely dried, tooth structure could be harmed

Application of Enamel Bonding

Bonding applications are available as self-curing, dual-cured, and light-cured systems

Some systems use a single application, whereas others require the mixing of two liquids

Each bonding system is different, and the material from one system is not interchangeable with that of another

Essential that the manufacturer's instructions be followed exactly with each product

Tooth surface receives the etchant material, which removes the smear layer

Bonding component is allowed to flow into these small defects and into the partially opened tubules in dentin

Material is allowed to either harden and act as a hybrid layer or remain in a liquid state while the restoration is being placed, to bond together the tooth and the dental material

Guidelines for Clinical Application of Bonding Products

Remove:

Remove any plaque or debris before beginning the bonding process

Avoid:

Avoid over drying the teeth; these products work best on a slightly moist tooth surface

Ensure:

Ensure that the bonding solution covers all surfaces

• Too much bonding material is better than too little; multiple layers work best

Avoid any contamination with saliva, blood, or debris, which will require the entire procedure to be redone

Allow as much time as possible for the bond to mature before completing the restoration

Application for Calcium Hydroxide

Liners are supplied either as a two-paste system or as a light-cured material

The material is placed prior to placement of the restorative material and with the use of a Dycal (calcium hydroxide) applicator

Placed only on the deepest dentin surface of the preparation

This material is not to be placed on enamel or in retentive grooves of the preparation

Application of Varnishes

Applied with a small disposable applicator or with a cotton pellet held in sterile cotton pliers

It is important to note that when a liner is placed, the varnish will be placed after the liner is applied

Because dental varnish interferes with the bonding and setting reaction of composite resins and glass ionomer restorations, the use of varnish is contraindicated with these materials

Desiccate

To remove moisture or dry out a material

etchant

an acidic agent used to prepare a surface for bonding of a dental material

Etching

process of roughing a surface microscopically with the use of an acid product

eugenol

colorless oily liquid made from clove oil that is an additive for its soothing qualities

hybrid layer

a thin layer created in between dentin and the adhesive resin that seals the space between the tooth and restoration 

insulating

material to prevent or reduce the transfer of heat or electricity

micromechanically

means by which a material and a structure lock onto one another through minute cuttings

obliterating

removing something completely

polymerize

the bonding process of two or more monomers to form a polymer

sedative

additive that has soothing effect

smear layer

very thin layer of organic particle debris found on newly prepared dentin

thermal

relating to heat