Common uses of alginate impressions
-diagnostic casts - study models
-preliminary impressions for complete dentures
-partial denture frameworks
-opposing casts for crown and bridge treatments
-repairs of partial and complete dentures
-provisional restorations
-custom trays for fluoride or w
Dental hygiene purposes and uses of study casts
-serves as a permanent record of patient's present condition
-give sharper delineation to and corroboration of the observations made during the oral exam
-an effective visual aid to use when oral conditions are explained and dental hygiene care plans are
What type of impression materials are available?
Rigid and Elastic
Within these categories, these materials are further classified as
reversible and irreversible
What is alginate?
Alginate is an Elastic Irreversible Impression Material
A negative replica of hard and soft tissues of the mouth into which plaster will be poured to construct a positive replica
impression
What are positive replicas used for?
study model, working model, or die
replica of an individual tooth or several teeth
die
Armamentarium needed for alginate
2 small bowls
alginate spatula (flexible)
water measure
one can alginate
plastic trays (max and man)
utlity wax to apply to the tray rims and one
bite registration wax
large bowl with warm water to soften the bite wax
lab knife
tray adhesive
What to consider when placing tray over teeth to check for size
-does it allow space on all sides of teeth or impinging on teeth?
-does it extend far enough to include tretromolar pad or max tuberosity?
After fitting, what is the next step?
Apply thin coat of tray adhesive on the tray then bead the tray with wax
Ratio of alginate mix?
one to one
What do you do before dispensing the powder into the rubber-mixing bowl?
tumble container in order to fluff the material. Wait to open to allow dust to settle
Do you add water to powder or powder to water?
powder to water
How long should mixing be completed?
one minute. Mixing time breaks up the impression material while a decrease in mixing time decreases the strength of the impression material
How should impression material look like?
smooth, glossy, and free of air bubbles
Which arch do you start with when taking impression first?
mandibular - prevents gag reflex
Where do you spread a small amount of alginate material before taking impression?
occlusal surface and palate of mouth
Operator position of max arch
11-12
Operator position of man arch
8 o'clock
How to load the man tray
begin loading the tray from the posterior lingual on one side, pressing material toward facial, then load the opposite side of the tray, finishing in the anterior aspect
How to load the max tray
begin loading from the posterior, pressing the material forward and downward. This will allow the material to fill the most anterior section and base of the tray
When taking the bite registration, how is it done?
soften wax in warm water, place wax on occlusal surface of max teeth, instruct pt to gently yet firmly bite down, 1-2 min
How to disinfect
rinse impressions and wax bite gently under running cool tap to remove any debris, shake to remove excess water. Spray impressions and wax bite thoroughly with disinfectant, place in a baggie for 10 min
What are some criterias for alginate impressions?
-include vestibules, frena, retromolar pads, max tuberosities, palate
-detail is sharp, -impression free of large folds of alginate
-no areas where the alginate has pulled away from the tray
-free of rips and tears
-alginate thoroughly covers the tray
-im
Where must impression be stored if not poured that day?
100% humidity
When pouring, there are three methods of pouring the cast. What are they?
double pour
boxing and pouring
single or inverted pour
impression and base poured separately
double pour
impression wrapped in boxing wax and both base and impression poured together
boxing and pouring
enough plaster mixed to pour impression and base at same time. This is the one we use
single or inverted pour
Equipment used for pouring
vibrator
model trimmer
scales
model-base formers
Does vibration increase or decrease air bubbles in the mix?
Decreases
What are other items needed for pouring?
2 rubber bowls for plaster
model plaster (200 gr for each arch)
measure plaster
scale for weighing
beaker for water
spatulas
vibrator and cover
rubber base-formers
lab knife
impression of max and man arch
alginate to make tongue
lab bench cover and paper
How many scoops of alginate to construct tongue?
one scoop (shared with 2-3 classmates)
How does the air bubbles rise?
pressing the bowl on vibrator
How do you apply plaster into tooth indentions?
Using small spatula to transport plaster to the molar area turning impression slightly to allow plaster to FLOW into tooth indentions
What do you also need to do once plaster is applied?
go to a bench where NO vibrating is taking place
What is important not to do when inverting the poured impression on the base?
NOT TO LOCK TRAY IN
What is the proper position to adjust the tray?
occlusal plane should be parallel with the base of the model-former
midline centered at the midline of the model-base former
What will be generated once everything is completed?
HEAT
approximately how long after can you separate impressions from cast?
one hour
What does one use to cut plaster away from periphery and free tray margin?
lab knife
Some self-evaluations of trimmed diagnostic casts
-Anatomic portion to base portion ratio 2/3 1/3
-Total height: 2-3 inches
-Bases are parallel
-max and man casts stand together
-retromolar pads and max tuberosities present
-vestibule present and contoured
-casts have good details and free of voids
-ant
Armamentarium for placing sealants
mirror, explorer, cotton pliers, sealant resin, etchant, gauze, curing light with shield, air/water syringe tip, saliva ejector, high speed suction, articulating paper, pumice, cotton rolls and garmer holder
Procedure to sealant
surface preparation
isolation
dry the tooth thoroughly
apply etchant
rinse thoroughly
dry the tooth and teeth
evaluate the etched surface
Apply primer
apply sealant
polymerize sealant
occlusal adjustment
evaluate the sealant
evaluate the sealant placement
MSDS Section I
Identity of Chemical
MSDS Section II
Hazardous ingredients
MSDS Section III
Chemical's physical and chemical characteristics
MSDS SectionIV
Fire and explosion hazard data
MSDS Section V
Reactivity
MSDS Section VI
Health Hazard
MSDS Section VII
Precautions for safe handling and use
MSDS Section VIII
Control Measures