Composition and Characteristics of Dental Porcelain

Flashcards on the composition, properties, advantages, indications, and contraindications of dental porcelain and porcelain fused to metal crowns.

Feldspathic Porcelain

A type of dental porcelain composed mostly of a vitreous matrix made of feldspars.

Glassy Phase

The vitreous matrix within feldspathic porcelain, primarily made of feldspar.

Feldspar

A mixture of anhydrated alumino-silicates, including potash and soda feldspar.

Potash Feldspar

A specific type of feldspar represented by the formula K2O·Al2O3·6SiO2.

Soda Feldspar

A specific type of feldspar represented by the formula Na2O·Al2O3·6SiO2.

Dispersion of Crystalline Phase

The mineral phase of feldspathic porcelain that includes silica and other oxides.

High-Ceram

A porcelain with dispersed alumina particles providing increased strength and elasticity.

Aluminous Porcelain

Porcelain containing 40-50% alumina crystals in a low-fusing glass matrix.

In-Ceram Alumina

An infiltrated glass ceramic considered a type of aluminous porcelain.

High-Fusing Temperature

Firing temperatures in the range of 1300-1400°C.

Medium-Fusing Temperature

Firing temperatures in the range of 1100-1300°C.

Low-Fusing Temperature

Firing temperatures in the range of 850-1100°C.

Ultra-Low-Fusing Temperature

Firing temperatures below 850°C.

Atmospheric Firing

A method of firing porcelain in normal atmospheric conditions.

Vacuum Firing

A method of firing porcelain that results in lower porosity.

Porcelain Fused to Metal Crowns (PFM)

A restoration made of a metal core covered with a layer of fused porcelain.

Core of PFM

The cast metallic framework of a porcelain fused to metal crown.

Opaque Porcelain

The initial layer of porcelain modified to mask the color of the metal framework.

Biological Properties of Dental Porcelain

Porcelain is biocompatible and inert, showing no interaction with surrounding tissues.

Chemical Properties of Dental Porcelain

Not soluble in oral fluids and resistant to acid attack.

Interfacial Properties

Dental porcelain does not adhere chemically to dental cements.

Mechanical Properties

Characteristics include brittleness, low fracture toughness, and hardness.

Thermal Properties

Low thermal diffusivity with coefficients similar to enamel and dentine.

Esthetic Properties

Excellent aesthetics and color matching, difficult to stain.

Practically of Dental Porcelain

Requires skillful manipulation and specialized equipment for handling.

Advantages of PFM Crowns

Stronger, more esthetically pleasing, with excellent retentive qualities.

Disadvantages of PFM Crowns

Require significant tooth reduction, subgingival facial margins, and are subject to brittle fracture.

Indications for PFM Crowns

Used for complete coverage, retainers for RPDs, and endodontically treated teeth.

Contraindications for PFM Crowns

Not recommended for patients with poor oral hygiene or young patients with large pulps.

Restoration Process

Preparation for a posterior crown involves specific techniques and considerations.

Post Preparation for Crowns

Important techniques and adjustments made during the preparation for crown placement.

Aesthetic Matching in Dental Porcelain

The challenge of accurately matching the shade of dental porcelain to natural teeth.

Expansion Coefficient

The property of dental porcelain that allows it to expand similarly to natural teeth.

Firing Shrinkage

The reduction in size that occurs during the firing of dental porcelain.

Metal-Ceramic Bond

The bond formed between the metal core and the porcelain layer in PFM crowns.