Titanium in contact with the human body without sensitization, growing phenomenon, cause cancer, birth defects can be combined with bone tissue, epithelial, connective tissue well, sso it is the metal material which has the best biocompatibility.
The physical properties of titanium
1. The density is small, the density of titanium is 4.51 g/cm3, about a quarter of gold (19.38 / cm3), cobalt chromium alloy (8.5 g/cm3) 1/2. So the titanium denture can reduce the burden of oral hard and soft tissue, is helpful to oral health.
2. Low heat conduction rate: Thermal conductivity of titanium (16.3 ~ 18 w/m. ℃) is only 1/17 of gold, and titanium titanium inlay, coronal protection pulp tissues from the advantages of hot and cold stimulation.
3. The little shrinkage: titanium line shrinkage rate of 1.75%, lower than co-cr alloy (2.13 ~ 2.24%), stainless steel (1.95 + / - 0.15%) and gold (1.76%), therefore the suitability of the titanium denture is wonderful.
4. The X-ray shoot half resistance: X-ray photos can show titanium crown tooth tissue lesions.
5. Nonmagnetic: titanium denture will not be magnetized in strong magnetic field.
The chemistry of the titanium
On the surface of titanium passivation film with acid corrosion resistance, so the titanium denture is not easy to corrode.
The mechanical properties of titanium
1. The hardness of titanium (HK240) between the enamel (HK345) and dentin (HK40 ~ 60), so the titanium artificial crown of occlusal surface will not too much wear on the jaw tooth occlusal surface.
2. The specific strength (tensile strength/density) of titanium is high,which is 1.3 times of aluminum, 1.5 times of steel. in 253 ~ 600 ℃ temperature range, the specific strength of titanium is the highest in metal material.So titanium denture solid, durable.
The difficulties in titanium production restoration,
1. high melting point
Titanium melting point 1668 ℃ + 4 ℃, which is 243 ℃ ~ 378 ℃ higher than co-cr alloy(1290 ℃ ~ 1425 ℃), thus, regular dental titanium casting machine not melt the metal.
2. Titanium extremely easy oxidation at high temperature
Chemical properties of titanium CN lively, easy to form the oxide film at high temperature, even at room temperature, titanium new aspects as long as the air exposure 1 ms, 10 a black is formed namely titanium surface thickness of oxide film,and increased to 50 ~ 100 a 1 min later.
3. Titanium casting performance is poor
Titanium density small, titanium liquid flow inertia small, illiquid, and high cooling speed, lead to the castability value is low.So you need to have enough pressure casting to make complete casting foundry.
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