Week 5 PP - Midterm Review Flashcards
What are the types of impression materials available?
-Alginate (irreversible hydrocolloid)
- Agar (reversible hydrocolloid)
-Bite registration using PVS * *
What types of impression trays are available (list at least 3)?
Full trays/stock trays
Sextant Tray - quick tray
Triple Tray * *
To prevent impression material peeling away from the tray during separation, what can be done?
add adhesive to tray
use perforated trays
Dr. Sait additionaly asked you to take elastomeric impression vs using wax that will record centril occlusion, what type of impression will you take?
Polysiloxane material - referred to as PVS, known as elastomeric impression.
Why are you looking into a mouth prior to taking impression?
to access oral cavity health status
to determine tray sizes
Should the impression tray fit loose or tight?
Loose
Upon reviewing C.O you determined that patient
has a moderate bony growth like tori present L -Q 3.
To make the tray more comfortable during
impression taking, what material should you use and
why?
Utility wax - add it to left lingual edge of tray (soften tray rim)
What type of alginate mix time should you use for your patient? What chemical ingredient controls setting time?
Mix time is 45 seconds
The temperature of water can affect setting time - cool water allows for more mix time
**
What chemical ingredient within alginate makes the material thick?
Zinc Oxide
What chemical ingredient within the alginate prevents material from breaking apart when removing from the mouth?
Potassium Titanium
Due to patient strong gag reflex, what techniques should you use during appointment?
- cold water or an ice cube held in the mouth can help trick senses
-salt (1/4 tsp) on the tongue to swallow just before the tray is inserted
-topical anesthetic may be applied to posterior palatal area, or a rinse can be one (NOT SPRAY )
Explain technique for placing impression on mandibular.
- ask patient to raise tongue before seating the tray, then can lower
-seat tray from posterior to anterior
-stand in front of the patient to the right
Explain technique for placing impression on maxillary.
-stand behind the patient
-seat the tray posterior to anterior
- have patient tilt head forward
How should impression tray be seated: anterior to posterior or posterior to anterior? and Why?
Posterior to Anterior - because.. it allows any excess impression material to flow towards the front of the mouth, preventing potential discomfort or choking from material going too far back in the throat, while also providing better visibility to ensure proper placement over the anterior teeth during seating.
Just seconds before seating maxillary tray in
your patients’ mouth, she grabs your hand and tells
you “STOP, I am not ready” What should you do?
Both impressions had been taken, what IPC steps
should be done prior pour and what office space will
be used to pour them?
impressions should be rinsed with cold water then sprayed with disenfectant, wait for 3 mins, rinse again with cold water - wrapped in moist paper towel in bag marked with patient name and information (including handle of tray)
Impression criteria for Study Models - what is a MUST?
-Tray is seated fully (bone height fully visible)
-Proper extension over mandible retromolar area is present
-Proper extension over maxillary tuberosity area
-Sharp anatomical detail is present throughout (palate, frenum, gingival, margin outline)
What are study models used for?
Used to evalute patient bite, shape of teeth, surrounding tissue
What additional tools are available to help with diagnosis?
Face Bow & Articulator
What are Preliminary Impressions used in preparation of?
-pre-treatment and post treatment records
-study and diagnostic casts
-in the fabrication of mouth guards (night guards & sport guards)
-whitening trays
-provisional coverage (temp restorations)
-orthodontic appliances
-custom impression trays
What is the thickening agent of alginate?
Potassium Alginte - derived from brown algae
What is the reactor that promotes gel formation in alginate?
Calcium Sulfate
What ingredient in alginate slows down the setting process?
Trisodium Phosphate
A filler that improves the rigidity and resistance of the gel in Alginate
Diatomaceous Earth
What creates the bulk to the alginate material?
Zinc Oxide
What provides strength to alginate?
Potassium Titanium
Describe how irreversible hydrocolloid material should be stored and handled
-deteriorates rapidly at elevated temperatures and in the presence of moisture
-material should be stored at cool temperatures and never in an area in which temp may be high. The lid of the container sshould be replaced promptly once dispensed to avoid exposure to humidity
It is recommended that alginate impressions be wrapped in a moist paper towel and poured within manufacturer’s instructions.
How should alginate material be prepared?
The mixed material should appear smooth, creamy & shiny. Inadequately mixed material is weaker, and is grainy, and takes much less accurate impression than properly mixed material.
There should be no dry alginate powder left within the mixing bowl or on the spatula after mixing. There should also not be visible graininess in the mixed material.
Why will a dental office require preliminary impressions?
Preliminary Impressions record details of the teeth and surrounding tissues. The impression produces an accurate 3D duplicate of the patient’s oral anatomy. The models formed from negative reproduction can be used as diagnostic aids, for the fabrication of dental appliances and as pre-treatment and post treatment records.
Armamentarium for Preliminary Impressions?
Impression trays
Air water syringe, LVE, mouth mirror
Alginate mixing bowls
Alginate mixing spatulas
Alginate
Room temp water
Utility wax
Criteria for selecting an impression tray.
Patient can be either upright or in supine position – depending on operator preference for maximum visibility. Clinical observations must be completed prior to tray selection. Oral conditions to be considered are… tori, high palate, crowded or rotated teeth, presence of lesions, or mobile teeth.
Operator must consider the tray width and length.
Width – must allow for adequate thickness of impression material on the facial and lingual of each tooth
Length – must allow for coverage of the retromolar area of the mandible and the tuberosity of the maxilla. On anterior, should be at least 2-5mm clearance labial to the most protruded incisor
When in doubt the larger tray is used rather than the smaller tray.
Patient Management for Taking Preliminary Impressions?
-Approach patient with confidence
-work quickly and efficiently as possible
-avoid excess material in the tray
-seat the tray from posterior to anterior
-instruct patient to breathe deeply through their nose efore tray is inserted and continue to afterward - bring head forward
