Test 3
Quiz yourself by thinking what should be in
each of the black spaces below before clicking
on it to display the answer.
Help!
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show | negative replica of the teeth and or gingival tissue in the mandibular and maxillary arch
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what are the requirements of impression materials? | show 🗑
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show | chain lengthening, cross linking, thermoset (permanent)
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show | solidification: waxes
gelation: doesn't get solid like wax, more jello like
thermoplastic (reversible)
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show | inelastic: rigid and inflexible
elastic:; rubbery and flexible
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show | rigid and inflexible used on edentulous patients (no undercut)
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show | impression compound (thermoplastic)
zinc oxide eugenol paste (chemical set)
impression plaster (chemical set)
impression waxes (thermoplastic)
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show | wax with added fillers, more brittle but flows mud less when compared to wax
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what are the characteristics of inelastic impression plaster? | show 🗑
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what are the characteristics of inelastic impression wax? | show 🗑
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show | rubbery and flexible
dentulous or edentulous
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show | hydrocolloids (water based impression material)
aqueous or non aqueous
non aqueous: elastomers and cross linked polymers
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show | agar and alginate
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show | thermoplastic and reversible hydrocolloid
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what is alginate characteristics? | show 🗑
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what do agar and alginate change to? | show 🗑
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show | changes from a rubber like gel to a liquid like sol by raising and lowering the temperature
physical change no chemical reaction
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what is the agar composition? | show 🗑
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what are the baths of the hydrocolloid condition for Agar? | show 🗑
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show | quick snap, DO NOT rock back and forth
pour up impression immediately in gypsum
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show | temperature at which hydrocolloid liquefies is not same temperature at which it solidifies
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what temperature does sol transform into gel liquid to gel | show 🗑
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show | 70 degrees C
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show | very accurate impression, works well in a wet environment
useful fro taking impressions when the margins of crown prep are subgingival
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show | require special equipment, unstable impression material, if stored must be 100% humidity, tears easily upon removal, can only be poured in gypsum ONE TIME
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show | diagnostic casts, fabrication of provision restorations, fluoride and bleaching trays, mouth protectors
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what are the characteristics of alginate? | show 🗑
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show | potassium alginate, seaweed, calcium sulfate: ensures proper set of gypsum material, sodium phosphate: retarder to delay reaction, diatomaceous earth filler
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show | cross linking causes gelation to occur
calcium sulfate dihydrate+ water = calcium alginate
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show | 20 C 70 F
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what is the working time for alginate | show 🗑
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what is the setting time for alginate? | show 🗑
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show | low cost, slight reaction with gypsum, good patient acceptance
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what are the disadvantages of alginate? | show 🗑
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show | alginate dries up and shrinks when left out in the air
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what is imbibition? | show 🗑
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steps for mixing alginate impression? | show 🗑
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steps fro placing alginate in tray and making an impression? | show 🗑
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how do you remove the alginate tray? | show 🗑
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show | 1 hour
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show | improper mixing, prolonged mixing, water to powder ratio too low
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show | premature removal from mouth
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show | air incorporated during mixing, moisture or berks on tissue
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show | inadequate cleaning of impression
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show | impression not poured immediately, movement of the tray during elation, renature removal from mouth, improper removal from mouth by rocking
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what are the types of gypsum? | show 🗑
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show | die stone
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show | mostly white, most porous form, irregular shape
usually used to make diagnostic casts, treatment planning and study models
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what is lab/dental stone? | show 🗑
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show | high strength or improved stone, most uniform, densest form, hard, abrasive resistant
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what is gypsum rock naturally made out of? | show 🗑
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what is gypsum rock in dentistry made out of? | show 🗑
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show | weaker and less resistant to abrasion
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what are the properties of plaster? | show 🗑
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show | calcium sulfate hemihydrate
it goes from calcium sulfate hemihydrate to a calcium sulfate dihydrate
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what is made by direct and rapid heating process in open air? | show 🗑
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what is made by steam pressure in a closed container? | show 🗑
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show | regular and uniform in shape, less porous, stronger and more expensive than plaster and referred to as alpha hemihydrate
used for casts of diagnostic purposes
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show | strongest, less expansive, more expensive strobe
used mainly for making casts or dies for fabrication of crowns, bridge onlay/inlay
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which stone requires the least amount of water? | show 🗑
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what does surface hardness depend on in gypsum? | show 🗑
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which stone has the greatest density? | show 🗑
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how much water do you mix for 100 g plaster powder? | show 🗑
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show | 28-30 ml
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show | 19-24
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if you increase the amount of water to plaster/stone... | show 🗑
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if you decrease the amount of water to plaster/stone... | show 🗑
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an increase in spatulation time will... | show 🗑
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does temperature affect dental stone? | show 🗑
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what does slurry water do to dental stone? | show 🗑
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show | retarder, slows down reaction
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show | accelerator, speeds up reaction
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show | length of time from the start of the mix until the setting mass reaches a ski hard stage
represents the available time for manipulating the product
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show | represents the length of time from the start of the mix until the setting mass becomes rigid and can be separate from the impression (30-45 minutes)
indicates the major completion of the hydration reaction
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what can you do to increase setting time of dental stone? | show 🗑
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show | increase mixing (longer mixing time, shorter setting time)
lower water powder ratio (creates a thicker mix)
add potassium sulfate (accelerator)
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what are preliminary impressions used for? | show 🗑
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what are final impressions used for? | show 🗑
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when selecting size of tray for impressions the width should... | show 🗑
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show | cover the retromolar pad, maxillary tuberosity and have 1/4 inch anterior clearance of the most protruded incisor
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show | vaulted palate, labial frenum, peripheral roll, palatine fovea, impression of uvula
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show | rinse casts under water, check drain in sink and hoses on model trimmer, make sure trimming platform is parallel to the counter top, make sure trimmer wheel is wet, remember to rinse periodically
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how should the back of the model be trimmed? | show 🗑
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how should the base be trimmed? | show 🗑
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show | trim the backs of both models together so that they are perpendicular to the midline of the mouth
use median raphe or labial frenum as guide
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how do you trim the maxillary cast? | show 🗑
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show | round off the anterior portion of the cast in the shape of an arch
arch should extend from the canine eminence to canine eminence
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show | posterior angles or heels of the cast at right angles to an imaginary line through the cuspids
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what should the total height of both casts in occlusion be? | show 🗑
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show | trim the sides of each parallel to a line through the central groove of the premolar teeth
lowest depth of the vestibule (2-3 mm buccal to the lowest depth of the vestiuble on each side)
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show | provides a dry, clean visible field, dark colors provide contrasting field and reduces eye fatigue, allows for more refined tooth preparation in absence of moisture from saliva while retraction cheeks, lips and gingival tissue
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show | swallowing, aspirating small objects and debris
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show | damage from rotary instruments and from dental materials which may be damaging
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what is the clinician protected from while patient wears rubber dam? | show 🗑
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what are the disadvantages to rubber dams? | show 🗑
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show | partially erupted teeth, third molars, malposed teeth
class V lesions on molars, asthmatic patients or psychological reasons
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what side should be facing the operator in rubber dams? | show 🗑
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what is the purpose of rubber dam retainers and how should it be placed? | show 🗑
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show | edge placement difficult, seal around tooth difficult and tissue trauma may occur
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show | the hole for the tooth to be restored is punched 1.0 to 1.5 mm facial to the alignment of the other holes
clamp is positioned 1 mm below lesion to avoid gingival floor collapse
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show | designated by a W in their identification
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how should you sterilize the rubber dam punch? | show 🗑
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what should you never use as rubber dam lubricant? | show 🗑
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show | 5 teeth
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show | lingually cusps of posterior teeth and cingulum of anterior teeth
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what should you do with higher/fuller papillae in rubber dam placement? | show 🗑
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what happens if the holes are placed too close together? | show 🗑
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show | bunching of the dam inter proximally and limited access to proximal surfaces
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show | smallest incisors
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show | incisors and cuspids
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show | cuspids and premolars
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show | premolars and molars
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what is the number 5 hole on the rubber dam punch used for | show 🗑
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Created by:
Chobchi
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