impression materials

agar

lab only material

reusable

impression materials

1 + 2= condensation rxn

polysulfide loses sulfate → stinky smell

condensation silicone releases ethanol = used for reduction guides/ outside of the mouth primarily

addition silicone (PVS) - addition rxn of 2 silicones, doesnt not reuse anything best thing you will use in pts mouth for actual inpressions *gold standard

polyether = very rigid + most expensive

EVOLUTION OF ELASTOMERIC IMPRESSION MATERIALS

polyether was made for dentistry use

*know yellow boxes bc its for boards

THE 4 ELASTOMERIC MATERIALS

*know other name for polysulfide, PVS + polyether

VISCOSITY & CONSISTENCY TYPES

MASTER COMPARISON TABLE

he said if you know this you will be good lol

POLYSULFIDE

known as: Mercaptan • Thiokol • The Original Elastomer

ADA Specification No. 19 | Condensation Polymerization

Light & Heavy Body Only

*know plasticizer only from slide

POLYSULFIDE — SETTING REACTION

POLYSULFIDE — CLINICAL PROFILE & SELECTION

*use for multiple crowns

*high shrinkage

* releases ethanol

CONDENSATION SILICONE

use in sim lab (Zetalabor)

used for reduction guide and temp stents

CONDENSATION SILICONE — CLINICAL PROPERTIES

ADDITION SILICONE (PVS)

THE GOLD STANDARD

Vinyl Polysiloxane • Polyvinylsiloxane • VPS • PVS

Addition Polymerization | No Byproduct | Best Dimensional Stability

ADDITION SILICONE (PVS) — COMPOSITION & SETTING

*hydrophobic but surfactants are added to this material

ADDITION SILICONE (PVS) — CLINICAL PROFILE

PVS — CRITICAL: POLYMERIZATION INHIBITION

POLYETHER

The First Impression-Specific Elastomer • Most Hydrophilic • Stiffest

Brand name: Impregum (3M) | Addition polymerization (ring-opening) |

No byproduct

MADE FOR DENTISTRY

POLYETHER — COMPOSITION, REACTION & PROPERTIES

*crosslink rubber = polyether, shortest working time but second longest setting time

hydrophilic it will start swelling → change dimensions (disinfectant time)

know shrinkage

TRAY SELECTION — CLINICAL DECISION GUIDE

more material added = more shrinkage

only custom tray for polysulfide

*know spacing

MIXING SYSTEMS — THREE METHODS COMPARED

1. takes too long to mix and can over mix

2. tip but in wrong, do not use first unmixed material

IMPRESSION TECHNIQUES — SIDE-BY-SIDE COMPARISON

REMOVAL, TIMING & DISINFECTION

CLINICAL FAILURES — ROOT CAUSES & PREVENTION

IF YOU REMEMBER ONLY 5 THINGS

The core clinic-ready facts

SPECIAL CLINICAL SITUATIONS

DIGITAL VS ELASTOMERIC — THE REAL-WORLD PICTURE