front 1 How are impression materials manipulated to shape like cakes? | back 1 Putting them in 60C water after shaping them |
front 2 How could you fix the distortion due to reliefe of internal stress? | back 2 By putting the impression in water immediately after removal |
front 3 How much is Coefficient of thermal expansion? | back 3 0.3% generally |
front 4 How much is Fusion temperature? | back 4 43.5C |
front 5 How much is glass temperature? | back 5 39C |
front 6 How much should you wait to prevent dimensional distortion? | back 6 1h |
front 7 How to fix the coefficient of thermal expansion error? | back 7 1-passing the impression over flame to soften it then obtaining the second impression to lower the shrinkage 2-spraying cold water on the tray before putting it with the impression in the mouth to harden the tray while the impression stays soft |
front 8 What affects viscosity? | back 8 1-temperature =1/viscosity 2-prrssure = viscosity 3-nature of the substance 4-time = viscosity |
front 9 What are hardness tests? | back 9 Brinell hardness number (BHN) Vickers hardness number (VHN) Knoop hardness (KHN) Rockwell hardness Shore A hardness test |
front 10 What are precautions in using impression materials? | back 10 1-long immersion in water, makes the material lose low weight parts of it that cannot be distinguished 2-overheating, makes the material sticky and hard to handle 3-Excessive wetting, messes the flow of material |
front 11 What are some examples of elastomeric impressions? | back 11 Polysulfide Polyether Addition silicones Condensation silicones |
front 12 What are some examples of irreversible hydrocolloid? | back 12 Alginate |
front 13 What are some examples of Reversible hydrocolloid? | back 13 Agar |
front 14 What are some examples of rigid Irreversible impressions | back 14 Zoe impression paste, impression plaster |
front 15 What are some examples of thermoplastic impression material? | back 15 Impression compound |
front 16 What are some examples of thermoset impression material? | back 16 Zinc oxide eugenol |
front 17 What are some material properties? | back 17 1-thermal conductivity 2-coefficient of thermal expansion 3-Flow 4-glass transition temperature 5-fussion temperature 6-surface detail reproduction 7-Dimensional Stability |
front 18 What are the advantages of using impression compound | back 18 1-cheap 2-reusable, you can also modify it after use for more accurate impression 3-doesn't cause irritation for patients |
front 19 What are the applications of Type I impression compound? | back 19 -primary impression -for making impressions on individual tooth -for border moulding(manipulation of the border of the impression by the outside tissue in order to catch those information as well -to check for over cutting or deep cutting in the inner portions of the teeth |
front 20 What are the applications of Type II impression compound? | back 20 To make tray |
front 21 What are the disadvantages of using impression compound? | back 21 1-cant record accurate details 2-uncomfortable for the patient becuase it comprises the tissue since they apply pressure on it 3-Distortion 4-Difficult to remove from undercuts(deep cuts in the inside portion of the teeth) 5-doesnt have a pleasant taste |
front 22 What are the usefulness of trays? | back 22 1-to carry the impressions 2-hold the material close to the teeth 3-avoid breaking during removal 4-prevent bending of the impression |
front 23 What degree is thermoplastic compounds generally warm? | back 23 45C |
front 24 What does impression plaster mainly made of? | back 24 Calcium sulphate hemihydrate that truns into Calcium sulfate dihydrate after reaction with water |
front 25 What factors produce significant internal stress in the impression material? | back 25 1-high thermal expansion 2-low thermal conductivity 3-high heat change between material and environment |
front 26 What is a 'wash' in Dental material? | back 26 A thin layer placed on top of an impression material to record endentulous(inside teeth) impressions |
front 27 What is adsorption? | back 27 The sticking of a material to the surface of another material but not going in it |
front 28 What is an example of high fusion compound | back 28 Tray compound |
front 29 What is an example of Low fusion compound | back 29 Green stick compound |
front 30 What is an example of medium fusion compound | back 30 Impression compound |
front 31 What is an example of reversible rigid impressions? | back 31 Impression compound |
front 32 What is fusion temperature? | back 32 The temperature where the material turns plastic |
front 33 What is galvanism? | back 33 Its the current produced between two dissimilar materials |
front 34 What is glass temperature? | back 34 The temperature that the material losses its hardness or brittleness |
front 35 What is hardness? | back 35 The resistance of an ability to be penetrated |
front 36 What is impression plaster used for? | back 36 For people who have flappy ridge |
front 37 What is shear stress? | back 37 Its a stress paralell to each other but not on the same line |
front 38 What is sorption? | back 38 Adsorption with absorbtion but not knowing the sequence in which they will happen |
front 39 What is surface wetting? | back 39 The ability of an adhesive material to wet and adherand(the material which the adhesive is stuck to) |
front 40 What is the advantages of using a cast model? | back 40 1-to make his diagnosis and treatment plan |
front 41 What is the bitting force of an individual with Fixed Bridges? | back 41 40% of an individual bite force |
front 42 What is the bitting force of an individual with removable Bridges? | back 42 15% of the original bite force |
front 43 What is the composition of Impression compound | back 43 Resin, like wax -filler, like Talc stone and soap stone -lubricant |
front 44 What is the contact angle? | back 44 The way we measure how well adhesive materials can stick to an adherand |
front 45 What is the difference between Brittleness, Ductility and Mellability? | back 45 Brittleness: is the ability to fracture near the proportional limit, without showing any deformations like glass Ductility: the resistance of a material to permanent deformation to tensile load Mellability: the ability to be spread thin into sheets without breaking |
front 46 What is the difference between Resilience and Toughness | back 46 Resilience: resistance of material for permanent deformation, the region of elasticity before turning plastic Toughness: resistance of materials for fracture, region of the graph before fracture |
front 47 What is the difference between Ultimate Strength/stress and Fracture strength/stress | back 47 Fracture strength: the stress at the point of Fracture Ultimate Strength: the stress at the point before Fracture happens, the highest point in the stress and strain curve |
front 48 What is the difference between wear and erosian? | back 48 Wear: resistance of a material surface to be torn apart by friction Erosion: resistance of a material surface to be torn apart by chemical reactions like acid attack |
front 49 What is the differnece between Primary and final impressions | back 49 1-Primary: -made by dentist or dental assistance -used to make custom trays, appliances, not so accurate models meant for diagnoses -for before and after treatment records 2-final: -made only by dentist -used to make reproduction of teeth or implants |
front 50 What is the most anti expansion material used on impression plaster | back 50 Potassium sulphate |
front 51 What is the most viscose impression material? | back 51 Impression compound |
front 52 What is Yield strength? | back 52 Its 0.1-0.2% offset in the stress-strain curve thats the limit point between the elastic and plastic region |
front 53 When do thermoplastic materials set? | back 53 When they get in the mouth becuase they are cooled to 37C |
front 54 Why do they put impression plaster in air tight container | back 54 To prevent it from sucking the moisture air which results in longer setting |