Classification

Rigid impression materials

(1) Plaster
(2) Compound
(3) Zinc oxide-eugenol

Flexible hydrocolloid impression materials

(I) Agar-agar (reversible hydrocolloid)
(2) Alginate (irreversible hydrocolloid)

Flexible, elastomeric, or rubber impression materials

(1) Polysulfide rubber (mercaptan rubber)
(2) Silicone rubber (condensation silicone)
(3) Polyether rubber
(4) Polyvinyl siloxane (addition silicone)
 

Physical reaction-cooling causes reversible hardening

Chemical reaction-irreversible reaction during setting

COMPOSITE RESINS

Components

• Filler particles-colloidal silica, crystalline silica (quartz), or silicates of various particle sizes (containing Li, AI, Zn, Yr)
• Matrix-BIS-GMA (or UDMA) with lower molecular weight diluents (e.g., TEGDMA) that correct during polymerization
• Coupling agent- silane that chemically bonds the surfaces of the filter particles to the polymer matrix

Root canal sealers

Applications

Cementation of silver cone gutta-percha point
Paste filling material

Types

Zinc oxide-eugenol cement types
Noneugenol cement types
Therapeutic cement types

properties

Physical-radiopacity
Chemical-insolubility
Mechanical-flow; tensile strength
Biologic-inertness

Gingival tissue packs

Application-provide temporary displacement of gingival tissues
Composition-slow setting zinc oxide-eugenol cement mixed with cotton twills for texture and strength

Surgical dressings
1.Application-gingival covering after periodontal surgery
2. Composition-modified zinc oxide-eugenol cement (containing tannic, acid. rosin, and various oils)

Orthodontic cements

Application-cementation of orthodontic bands
Composition-zinc phosphate cement 

Manipulation

Zinc phosphate types are routinely mixed with cold or frozen mixing slab to extend the working time
Enamel bonding agent types use acid etching for improved bonding
Band, bracket, or cement removal requires special care
 

Properties-improve with filler content

Physical

Radiopacity depends on ions in silicate glass or the addition of barium sulfate (many systems radiolucent)
Coefficient of thermal expansion is 35 to 45 ppm/C and decreases with increasing filler content
Thermal and electrical insulators

Chemical

Water absorption is 0.5 % to 2.5% and increases with polymer level)
Acidulated topical fluorides (e.g., APF) tend to dissolve glass particles, and thus composites should be protected with petroleum jelly (Vaseline) during those procedures
Color changes occur in resin matrix with time because of oxidation, which produces colored by-products

Mechanical

Compressive strength is 45,000 to 60,000 lb/ in2, which is adequate
Wear resistance-improves with higher filler content, higher percentage of conversion in curing, and use of microfiller, but it is not adequate for some posterior applications
Surfaces rough from wear retain plaque and stain more readily

Biologic

Components may be cytotoxic, but cured composite is biocompatible as restorative filling material

Investment Materials

Investment is mold-making material

Applications

a. Mold-making materials for casting alloys
b. Mold-making materials for denture production

Classification

a. Gypsum-bonded investments (based on gypsum products for matrix)

b. Phosphate-bonded investments

c. Silicate-bonded investments

Components

a. Liquid-water or other reactant starts formation of matrix binder by reacting with reactant powder
b. Powder-reactant powder, filler, or modifiers

Manipulation

a. P/L mixed and placed in container around wax pattern
b. After setting, the investment is heated to eliminate the wax pattern in preparation for casting