Oleh :Bimo Rintoko, drg., Sp.Pros.

1. Any of various solid or semisolid amorphous natural organic substances that usually are transparent or translucent and brown to yellow; usually formed in plant secretions; are soluble in organic solvents but not water; are used chiefly in varnishes, inks, plastics, and medicine; and are found in many dental impression materials

2. A broad term used to describe natural or synthetic substances that form plastic materials after polymerization.

They are named according to their chemical composition, physical structure, and means for activation of polymerization

The Journal of Prosthetic Dentistry., July 2005. The Glossary of Prosthodontic Terms. The Academy of Prosthodontics, Vol. 94 number 1

Why? Desirable qualities:

Good esthetics Cheap Easy to process

Disadvantages: Not strong enough Susceptible to distortion Low thermal conductivity Radiolucent

Denture base material Denture repair Denture teeth Soft liners Construction of customized trays Soft tissue replication on cast metal

framework

Acrylic Denture

Acrylic Resin

I. Heat-CureII. Cold/Self cure

• The reaction is an addition polymerization reaction to convert MMA (methyl methacrylate) to PMMA (polymethyl methacrylate).

• Mono= single• Poly= many

Powder :• Beads or granules of PMMA• Initiator: benzoyl peroxide • Pigments • Opacifiers : titanium/zinc oxide• Plasticiser : dibutyl phthalate• Synthetic fibers : nylon/acrylic

Liquid :• Methyl methacrylate monomer• Cross-linking agent : ethylene glycol

dimethacrylate. This component improves mechanical properties

Composition : identical to heat cure resin except polymerization is initiated by tertiary amine (e.g. sulfinic acid or dimethyl-p- toluidine). They contain an inhibitor (hydroquinone) that destroys free radicals to prolong working time

Smaller polymer beads are used in cold cure resin to ease dissolution in monomer.

Cold curing method results in a polymer with a lower molecular weight leading to : Lower strength Residual uncured monomer Lower color stability, more prone to yellowing More prone to creep and therefore distortion

1. Resin Matrix2. Glass Filler Particles3. Coupling Agent4. Initiators and Accelerator

1. Microfill Composite2. Hybrid Composites3. Nanocomposites4. Flowable Composites5. Core Composites6. Indirect Resin Composites7. Ormocers8. Ceromers9. Fluoride-releasing Resin Composites

1. Tooth-coloured, have excellent aesthetics and good colour stability.

2. Mercury-free.3. Conservative of tooth substance as

mechanical retention and resistance features are not requaired.

4. Can be bonded to enamel and dentine.5. Low thermal conductivity, insulating pulp

from temperature changes.6. No galvanic potential.

1. Shrinkage on polimerization (0,6-9% by volume)

2. The dentin-composite bond may degrade with time.

3. The coefficient of thermal expansion of resin composite is typically two to six time higher than that of tooth substance.

4. Sorbtion of water by resin composite.