Dental Ceramics Research Paper

INRTODUCTION

Dental ceramics are basically oxide based glass-ceramic system used in restorations and other dentistry applications. They should be easily shaped, resistant to corrosion and have appropriate aesthetic appeal.

These are used to produce dental prostheses which can be used to replace damaged or missing dental structures. Ceramics and glass are brittle; they display high compressive strength and low tensile strength.

In normal chewing, teeth are encountered to mechanical stress of about 20 MPa 1000 to 3000 times a day. However, a hard biting may produce stress of about 100 MPa. Abrasive wear is also possible, since most people grind their teeth. The cyclic loading occurs in fluid (water) and has pH value ranging from 0.5 to

No one would want their tooth replacement to be black or grey; the replacement should also look like its neighboring teeth. Thus, the ability to tailor color, translucency and fluorescence becomes the main acceptance criteria.

Two interrelated properties that are often quoted regarding ceramics for structural properties are: 1. Strength 2. Fractural toughness

Strength

The capacity of an object or substance to withstand pressure is called the strength of the substance. Increased crystalline-filler content within the glass matrix, finer and more even distribution of particles, has resulted in significant improvements in fractural strength of ceramic materials. However, due to inherent weakness of the glass matrix, strength improvements are still limited. Stresses can cause a crack to grow through the matrix, resulting in failure of the restoration.

Fractural toughness

Fracture toughness is a measure of a material’s ability to resist crack growth. Materials ultimately fail due to crack propagation. Thus, a material having higher fractural toughness is more ideal for restoration as more energy is required to instigate crack growth.

Other factors include stress corrosion (crack growth caused by chemicals) and residual flaws in the

• Al2O3, ZrO2 are prepared according to the geometry of required restoration, glued by barbotine, which is then pre-sintered, generating a solid structure with desired strength.

Procedure

• The coefficients of thermal expansion of the bulk ceramic powders are measured using an alumina rod dilatometer.

• X-Ray diffraction is used to identify the crystalline phases of the powders.

• Using Scanning Electron Microscope, chemical composition and average particle size are observed.

• Al2O3-ZrO2 is mixed with sufficient water content and deflocculant and a suspension is obtained which is molded desirably using a plaster mold.

• Excess liquid is removed is removed from the mold by giving time for the sample to shrink, thus allowing its withdrawal from the mold. Material undergoes pre-sintering which brings out samples with low relative density that has open porosity.

• The glass powder is infused in the pre-sintered ceramic for the minimization of