DMS Colloq. PDF

DMS 1. In Dentistry the gypsum is used for..? → Impressions (negative form) & for manufacturing of models (plaster 2. Types of dental materials according to their structure are: → Metals, metalloids, non-metals; amphorous, crystalline 3. Which materials are “transparent” → glass, Acryli...

DMS 1. In Dentistry the gypsum is used for..? → Impressions (negative form) & for manufacturing of models (plaster 2. Types of dental materials according to their structure are: → Metals, metalloids, non-metals; amphorous, crystalline 3. Which materials are “transparent” → glass, Acrylic 4. What does HRB mean? → Ball indenter 56…60 HRB of Rockwell hardness test 5. What is “density” of the material? →A mass of substance in a unit of volume (p=m/V) 6. How the Brinell hardness is designated? → HB / BHN: 185 HB 7. What is “absorption”? → Property of material to let light pass through it 8. The types of dental materials according to the place & time of their usage: → Basic materials – remain long time in the oral (filling materials) → Auxiliary materials – remaining short time in the oral (impressions) → Laboratory materials – extra orally (gypsum for models) 9. What does “value” mean? → Lightness or darkness of the colour: at the top light, at the bottom dark 10. The “black” body → Absorbs all the light; Value of 0 11. During gypsum preparations, the Gilmore needles are used to measure… → The difference between the initial & final setting time of the gypsum 12. The setting time of gypsum can be accelerated by…? → All mentioned here can be used for acceleration of setting time o. → Accelerators like K2So4, NaCl 13. What is the difference between A1 and A4 of VITA shade guide? → A1-A4: Chroma increases + value decreases with increasing from No. 1 to 4 14. 1 ß-hemihydrate of CaSo4 is obtained in…? → In furnaces; T= 150-200°, 24-36h, normal pressure 15. Which test is static? →Mechanical test (tensile strength, compressive strength, bending / torsion strength test) 16. The “vacancy” is… → empty spaces, occur at high temperatures when atoms frequently/randomly change their position 17. What the main component of impression plaster? → Plaster of Paris (soft mineral of calcium sulfate dihydrate CaSo4*2H20); ß-hemihydrate 18. What is “ultimate tensile strength”? → Max. load of that specimen sustains during tensile test, point of failure/ rupture 19. What is the main component of type IV dental stone? → modified α-hemihydrate calcium sulfate 20. What is designation of “ultimative tensile strength”? → Is the reaction of the material to forces being applied in tension can be quickly determind by pulling on the material 21. Brinell hardness test is used for…? → Determining the hardness of metals & alloys 22. What types of strain exists? → Elastics/reversible; Plastics/irreversible 23. A “space lattice” is? → Any arrangement of atoms in space in which every atom is situated similary to every other atom 24. The setting time of gypsum can be retarded by…? → increasing o. decreasing the rate of crystal growth respectively 25. Vickers hardness test is used for…? → Testing of hard & brittle materials like porcelain 26. Where was the first amalgam developed as filling material? → 1919 US Army 27. What is “fatigue strength” → Is the maximum stress that can be maintained without failure over an infinite number of cycles. 28. What is the “heat capacity” o. “specific heat”? → The property of the material to absorb heat Heat capacity: is the heat necessary for increasing the temperature of 1g substance with 1°C. Specific heat: Is the result of heat capacity 29. The types of dental materials according to their biological properties are: → biologically tolerable, inert and active material 30. How the Vickers Hardness is designated → HV and VHN; 160HV 31. What is “phosphorescence”? → Specific type of photo-luminescence in which the materials emits light long time after excitation 32. What is “thermal conductivity”? → The property of the material to absorb the heat 33. What is Adhesion? → A surface attachment process 34. Conductors are: → Materials that have a high thermal conductivity 35. Electric conductors are: → Crytalline materials: metals and alloys 36. The surface of … reflection processes high brightness → mirror-like 37. The Rockwell-hardness test is characterized by… → Using the steel ball o. diamond cone and measuring the depth of penetration 38. What is designation of “yield strength”? → sigma 0,2 39. Can we measure the hardness of metal alloy by shore hardness test? → No 40. The “dislocation” is… → linear defect, formed by many vacancies in one line 41. Compression test is used for determining the strength properties of… → Brittle materials 42. How many forms of CaSo4 hemihydrate exists? → α-& ß- hemihydrate 43. What technological properties should have dental materials? → high durability, workability, fluidity, welding ability and forging ability 44. What is “fluorescence”? → Specific type of photo-luminescence where the substance emits light only during excitation 45. Work time is? → Time available to us a workable mix 46. What is “electrical conductivity”? → The ability of metals to conduct electric current to the presence of electron “gas” 47. What does HSH mean? → Shore hardness 48. What is the main component of type IV dental stone? → α-hemihydrate 49. What is the “ultimate tensile strength”? → The max. load the specimen sustains during the tensile test 50. What biological properties should have dental materials? → Harmless, non-toxic, chemical inertness and corrosion resistance 51. What type of mechanical test exist according to the allied load? → Resilient, ductile and brittle 52. The Vicat needle is used to measure? → Setting time 53. What is “impact strength”? → The energy required to fracture a material under an impact force 54. Whos the “father of the modern dentistry”? → Chaud Fauchard 55. In mirror-like reflections.. → The incident angle is equal to the reflected angle 56. What does “hue” mean? → It describes the dominant colour of an object, referring to the dominant wavelengths present in spectral distribution 57. What is “technological process”? → Combination of different methods an operations for treatment of materials 58. Knoop hardness test is used for? → Hardness of tooth enamel can be compared to that of gold, etc. 59. The structure of amorphous materials is characterized by: → Temp. above 50°C 60. What are the main groups of materials used in Dentistry today? → Impression materials, luting materials, filling materials, artificial teeth o. → Polymers (crowns..), Ceramics, Composite, Metals 61. Which factors influence the fatigue of the materials? → Surface roughness – for brittle materials with rough surface → Surface stress state – the fatigue cracks appear in the later stage → load value and frequency – the lower load and lower frequency 62. In W/P ration increase …? → When W/P increases, the setting time increases, strength of product & setting expansion decreases 63. What is Imbibition? → Acrylic plastic absorb liquids & enlarge volume by 0,5-2% , most intensively during first 24h  o. → Is the act of process of imbibition or absorbing the liquids resulting in dimensional changes 64. What does KHN mean? → Knoop hardness 65. Setting time is.. → Time that elapses from the beginning of mixing until the material hardens 66. Which material has the highest elastic modulus? → Resilient material 67. The Brinell hardness test is characterized by… → Steel ball is pressed under a specific load into the polished surface of a material for a definite time; diameter of impression is measured and hardness calculated 68. Where is the first amalgam developed as filling material? → 1890 in USA 69. How many types of “reflection” of light exists? → Mirror-like (incident angle = reflected angle), scattered diffuse (surface roughness> incident light wavelength), direct diffuse (surface roughness is commensurable with the incident light wavelength) 70. Insulators are.. → Materials of low thermal conductivity, amorphous 71. Which test is static? → Tensile, compressive, bending & torsion strength test 72. What is the main component of “model plaster”? → calcium sulfate hemihydrate (90%) ß-hemihydrate 73. What is “refraction”? → Change in direction of wave due to change in its speed 74. What is the “melting temperature”? → TM = melting/ solidification temp or melting point of pure metal → It is the equibrilium at which heating of a pure metal, compound etc. productes change from solid to liquid 75. Conductors are… → Material of high thermal conductivity 76. The Mohs hardness test is characterized by… →Measure how resistant a sample is to fracture or plastic deformation due to friction from a sharp object → Scratch test 77. The initial set of gypsum can be measured by… → Gillmore needle test → Loss of Gloss (LG) test 78. Which test is cyclic? → Fatigue test 79. Mixing time is… → Time from addition of the powder to the water until the mixing is completed (20-30s) 80. What is “plasticity”? →Permanent deformation under load 81. Electric insulators are… → Porcelain, polymers 82. What is “strength” of materials? → Strength of a material; its ability to withstand an applied stress without failure 83. What machine is used for impacted test? → Pendulum 84. The max. force of muscles, closing the mandibular is up to: → Masseter 85. What is the type IV intended for? → For preparing dies for fixed protheses 86. What does W/P ratio mean? → Important factor in determining physical and chemical properties of the product o. → Expresses the ratio of water and hemihydrate powder 87. What type of stress exist according to the nature of the applied forces? → Tensile, compressive, shear 88. The maximal forces for breaking the food are up to: →980,7N (100kg) 89. The “wettability” is → ability to be welded (melting + pressure) = joinability 90. What are “ductile” materials? → Due to permanent deformation the sample remains deformed after removing the loading (e.g. Waxes) 91. Alpha-Hemihydrate of CaSo4 is obtained in… → Type II gypsum 92. When were the composites developed as filling material? → in 1966 93. Which materials are “translucent”? → Zinc silico phosphate cement, porcelain 94. What are volume changes of the impression gypsum? → Extension +0,15% 95. What is the application of the alginate impression materials? → For preliminary impressions, study models & for removable fixed partial dentures 96. What are the main types of crystalline lattice of metals? → Body-centered cubic (9 atoms), face-centered cubic (14 atoms, highest amount of atomes) hexagonal 97. What is the gypsum hardness? → Mohs scale 98. Which colours are “primary”? → Red, blue, yellow 99. What is “luminescence”? → The property of materials to absorb energy and then emit is as visible light → Two types: Fluorescence, Phosphorescence 100. What is “fluity”? → The ability of a molten metal to flow and fill a channel or cavity 101. Which gypsum type possess the highest expansion? → Type V (0,30%) 102. What is “stress”? → Is the force per unit area 103. How is the Knopp hardness is designated? → HK / KHN 104. Which factors influence on dental materials in oral environment? → Physical, chemical, biological & mechanical 105. The “white” body? → Reflects all the light 106. In “hydrophilic material” the contact angle of water is..? → 0° 107. The “coefficient of thermal conductivity” – k is..? → The heat quantity in call is that passes through 1cm thick specimen having 1cm^2 cross- sectional area, when temperature difference between the surface perpendicular to the heat flow is 1° k 108. Where was the first amalgam developed as filling material? → USA 1890 109. The Vicker hardness test is characterized by..? → Square-based pyramid pressed under a specific load into the polished surface of a material of a definite time 110. What is designation of “elastic limit” →E 111. What is the type II intended for? → Study models