Dental Materials Review

Flashcards covering key concepts from the dental materials lecture.

What materials are used to make special trays?

Acrylic, shellac, and compound

What is the use for special trays?

Border tracing and taking 2ry impression for completely edentulous patient IVP.

What materials are stock trays made from?

Plastic and metal

What is the use of a stock tray?

Taking 1ry impression

What are the types of stock trays?

Perforated, solid, rim lock

What type of impression material is Speedex?

Condensation silicone impression material

What is the use of Speedex?

Taking 2ry impression for dentulous patient for the fabrication of a fixed restoration

What are the advantages of Chaco Spedita?

Better elastic properties than other elastomeric impression materials and alginate, Pleasant taste & odour and no staining, Good working & setting time, Stock tray is used (putty wash technique)(no need for custom tray), higher tear strength, more elastic recovery, more dimensionally stable, record fine details better than alginate

What are the disadvantages of Chaco Spedita?

Poor dimensional stability compared to addition silicone (high polymerization shrinkage + ethyl alcohol byproduct). So imp should be poured within 30min, Hydrophobic, so poor wettability, Limited shelf life due to un stable activator

What is the use of Cavex Outline?

Taking 2ry impression for completely edentulous patient with no undercut

What are the disadvantages of Zinc Oxide Eugenol free impression material?

Non-elastic, Sticks to patients' lips and checks & dry skin, Eugenol cause burning sensation with some patients, Can't be corrected (only in thin area)

What are the advantages of composite resin restoration?

Esthetics, Conservation of tooth structure as its bonded to the tooth micro-mechanical, Adhesion to tooth structure, Low thermal conductivity, stronger than other esthetic restorations, Alternative to amalgam, cheaper to be used as veneer than porcelain

What are the disadvantages of composite resin restoration?

Technique sensitivity, Polymerization shrinkage, Post-operative sensitivity, Decreased wear resistance, discoloration from staining food, tea, coffee and nicotine, expensive compared with amalgam

What is the use of acid etchant?

Etching (creating micro pores in the surface of enamel) enamel and dentin before bonding

What are the advantages of acid etchant?

Strong acid provides adequate etching of enamel

What are the disadvantages of acid etchant?

Causes hypersensitivity when used on dentin, Causes collapse of collagen fibers if followed by air dryness

What is the use of a bonding agent?

Provides micromechanical retention to dentin, Restore teeth with composite restorative material by bonding it to the tooth structure, Restore teeth with amalgam using an adhesive technique, Repair existing restorations (composite, ceramic and amalgam), Seal pits and fissure of posterior teeth, Change shape and color of anterior teeth, Bond indirect restorations, (metallic crowns, all-ceramic restorations, orthodontic brackets)

What is the use of a light cure device?

Photo polymerization of Composite restorations, Dual cure RMGI, Dual cure composite resin, Bonding agent

What is the use of chemical cure acrylic resin?

Making special tray, repair material for acrylic dentures, making trial denture base

What are the advantages of using chemical cure acrylic resin?

Denture base fabrication in short time, Dimensional accuracy due to lower polymerization shrinkage

What are the disadvantages of using chemical cure acrylic resin?

Higher residual monomer that could irritate the patient's soft tissues, Lower degree of polymerization, Lower mechanical properties as stiffness & strength, Higher porosity, Higher water sorption, Color instability due to oxidation of 3 ry amine

What are the advantages of acrylic teeth compared to porcelain teeth?

More comfortable (no clicking sound, resilient and transfer less pressure to the gums), Easily adjusted, Lighter in weight, Bond chemically to denture base, Doesn't cause wear to the opposing dentition, CTE is similar to denture base (avoids crazing and separation), Stronger in thin section, High impact strength

What are the disadvantages of acrylic teeth compared to porcelain?

Easily stained, Low wear resistance, Less color stability

What are the advantages of porcelain teeth?

Resistant to staining, high wear resistance, more color stability

What are the uses of dental compound impression material (green sticks and cakes and sheets)?

taking 1ry impression for edentulous patient with no undercuts (cakes), border tracing/ molding for acrylic special tray (green sticks)

What are the advantages of using dental compound?

Can be added, corrected, Can be sterilized & reused, Easily manipulated, Not toxic & Not expensive, Compatible with model and die materials, has adequate shelf life

What are the disadvantages of using dental compound?

Non-elastic, doesn't withdraw from undercuts, so it is used only with edentulous patients, Has low flow so it doesn't record fine details, dimensional changes occur during setting due to thermal contraction, Dimensional changes occur on storage due to relief of internal stresses, Transfer infection (non-hygienic)

What is the use of a rubber bowl and mixing spatula?

Mixing alginate impression material

What are the composition of alginate?

Na/K alginate, CaSO4.2H2O (reactor), Na3 PO4 (retarder), K. Ti fluoride, Fillers, Flavoring, coloring and disinfecting agents

What is the use of alginate?

Used for making primary impression to produce a primary cast for Primary (diagnostic) cast for both dentulous and edentulous patient, fabrication of a special tray as in complete, partial denture, Opposing arch as in crown and bridge, Provisional restorations, night guard & fluoride application

What are the advantages of alginate?

Inexpensive, Easy to use, Hydrophilic (good wetting for oral tissues), Stock trays with no need for special tray, Displace moisture, blood, fluids

What are the disadvantages of alginate?

Dimensionally unstable, Lower detail reproduction, Low tear strength, Difficult to disinfect, Can't be electroplated

What are the advantages of heat cured acrylic resin?

Higher mechanical properties and higher degree of cross linking compared to self cured acrylic, Less residual monomer, Less porosity and more color stability, Less water sorption

What are the disadvantages of heat cured acrylic resin?

Curing time is much longer than self cured acrylic

What is the use of acrylic denture base?

Rests on the soft tissue, Support and retain artificial teeth, Distribute stress on soft tissue equally, Restores the shape and color of the alveolar ridge and gingiva

What are the advantages of an acrylic denture base?

More esthetic, Accepts addition and repair easily, Less expensive, Lighter in weight

What are the disadvantages of an acrylic denture base?

Poor thermal conductivity, Poor color stability, Poor mechanical properties

What is the use of phosphate bonded investment?

Casting for metal above 1200 degree

What is the use of an amalgamator?

Mechanical mixing of amalgam capsules

What is the definition of dental amalgam?

an alloy of Hg with Ag-Sn

What the uses for dental amalgam?

Direct posterior filling material, Buccal pits and Core material for crown buildup, Filling material in class III at the distal surface of canine, Pin retained amalgam and Amalgam die material, Retrograde filling material

What are the advantages of using dental amalgam?

High strength and mechanical properties, Low cost, I can make good proximal contact

What are the disadvantages of dental amalgam?

Toxicity from Mercury

What are Zinc Oxide Eugenol properties?

The set cement has a PH of about 7 (neutral), It has an obtundent effect on the pulp due to the prescence of Eugenol, It has a bacteriostatic action also due to the eugenol content

Why can't you use zinc oxide eugenol cement as a liner under composite?

As it does inhibition for polymerization reaction.

What is the material that orthodontic wire is made from?

Wrought alloy

What is the use of Mortar & pestle?

Hand mixing of dental amalgam, Trituration

What are amalgam carriers used for?

are the dental restoring instruments that are used to fill cavities with amalgam filling materials. They carry freshly prepared restorative material into the cavity.

What is the use of an anatomical burnisher?

Used for polishing and contouring amalgam fillings

What is the primary function of a dental amalgam condenser?

is to densely pack the amalgam material into the prepared tooth cavity, ensuring a strong and durable restoration.

What are the uses for Zinc phosphate cement?

As base under amalgam act as thermal insulator

What are the properties of Zinc phosphate cement?

The PH of the freshly mixed cement is about 1.3-3.6, PH increases to about 6 after one hour, Become neutral after 48 hours, The zinc phosphate cement gives a maximum film Thickness of 25 microns, Low solubility, The mixed zinc phosphate cement reaches 50% Of its final strength within the first 10 minutes After mixing, Reaches its final strength after about 24 Hours, The compressive strength Varies from 95 to 135 Mpa, The cement bonds to the tooth structure by mechanical Interlocking, This cement can be used as an insulating base Under metallic restorations.

What are glass ionomer cement uses?

filling in Non stress bearing area as class V and in children, in core

What are the advantages of glass ionomer cement?

Chemical adhesion to the tooth Surface, Good marginal seal, Anticariogenic property, Biocompatibility, Minimal cavity preparation required

What are the disadvantages for using glass ionomer cement?

Low fracture resistance, Low wear resistance, Water sensitive during setting, Less esthetic compared to Composite

What is the use for paper points?

Dryness of canal before placement of restoration

What are the materials that make up a hand endodontic file?

stainless steel or Ni-Ti or carbon steel

What is the uses of sprue?

Fixation of Wax pattern and act as channel for exit wax and entery of metal and act as reservoir to compensate any shrinkage in metal

What are the advantages of Gutta Percha?

Adaptability, Easy manipulation, Easy removal, Good biocompatibility.

What are the advantages of Gutta Percha?

Lack of adhesion to dentin, Not flexible enough to extend in severely curved canals, Shrinkage, Cannot be heat-sterilized, Oxidizes in air and light and become brittle

What is Calcium hydroxide cement or dycal in pulp caping used for?

stimulate formation of reparative dentin or secondary dentin