Random Pearls of Dental Materials (2)

51. Light wavelength for visible light cure resin 400nm with shrinkage towards light source
52. Cold molding performed with gold
53. Metal which are drawn readily into sheets are Meleable
54. Hg content of amalgam If decrease then strength increase
55. Silver increases expansion & strength
56. Silver decreases flow & setting time
57. Zinc in amalgam makes it plastic & have scavenging effects
58. Gamma is the strongest phase( SiT) i.e silver tin
59. Gamma 2 is the weakest phase (TiM) I.e tin & mercury
60. Decrease tarnish and decrease corrosion resistance would increase creep
61. Least wetable material is Teflon
62. Vitaliam = Cobalt & chromium
63. Pickling: 50% Hcl. It removes impurities
67. 1° Corrosion product 》》》 Silver sulphide
68. Softing heat temperature will increase ductility
69. Most maleable & ductile is gold & cold moulding is for gold
70. Direct gold filling A/E increase Thermal conductivity
71. Decreased hardness of steel is due to cobalt
72. Quartz is strengthener for porcelain
73. kaolin is binder for porcelain
74. Dental stone is strengthener for gypsum
75. All elastic impression materials are hydrophobic except polyether (hydrophilic & hypersensitivity reaction )
76. Most flexible Impression material 》》 Addition silicone
77. Least deformed Impression material 》》 Addition silicone
78. Most Rigid Impression material 》》 ZnOE
79. Elastomeric Impression material least shelf life & longest curing time》》 condensation silicone
80. Least stiff, electroplated and mostly deformed Impression material >> Poly sulfide
81. Eutectic Alloy 》 silver & copper
82. Modulus of elasticity 》 strength
83. Elastic Limit 》 Resilience
84. Ductility 》 %age elongation
85. Impression compound flow 6%
86. Impression compound thermal contraction 0.3%
87. Impression compound fusion temperature 45%
88. Impression compound filler chalk
89. Soft and ductile 》 Ferrite and Austen
90. STAINLESS steel least corrosion 》 Martensite ( hyper for cutting instruments )
91. AGE HARDENING –》 200-450 °C for 15-30 minutes and Quenching
92. HARDING heat Treatment –》 heat 45°C and cool 1/2 hrs
93. Tensile Test –》 DUCTILITY —》 elongation (stretch ) [TDS]
94. Compressive Test —》Maliability —》Hammered to sheet[CMH]
95. ◇—》Vickers & knoop Hardness Test
●—》Brinell Hardness Test
96. Knoop Hardness of Enamel 600 KHN
Knoop Hardness of Dentine(D) 65 KHN
Knoop Hardness of Silicate (S) 70 KHN
Knoop Hardness of Amalgam 90 KHN
Knoop Hardness of Acrylic Resin 16 KHN
Knoop Hardness of Gold 32 KPN
Knoop Hardness of composite (C) 55 KHN
Important KHN are 55 65 70 ( C D S)

97. Ethyl alcohol is a byproduct of condensation silicone
98. Hydrogen gas is by product of Addition silicone
99. Contracts because of cross linking >> Addition silicone
100.
VHN hardness of type 1 gold 50-90
VHN hardness of type 2 gold 90-120
VHN hardness of type 3 gold 120-160
VHN hardness of type 4 gold 160-200

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