Metal ceramic crowns or porcelain-fussed-to-metal crowns, are made of a metal frame consisting mainly of chromium (Cr), and cobalt (Co) and covered with a special ceramic material (porcelain)
In older days, the composition of the metal were used nickel (Ni) instead of cobalt, but the usage was abandoned due to allergic reactions
Thus, these alloys are characterized chromium-cobaltium while in the composition contained a small amount of other metals such as molybdenum (Mo) which is indeed responsible for the discoloration (graying) of the crown after years passing by, iron (Fe), carbon (C), magnesium (Mg), and others
Advantages :
• They can be used for big fixed prosthetic restorations or supports of removable prosthetic
• Good durability at the time
• Resistance to vibration
• Does not demand big tooth preparation in relation with all ceramic crown
• Does not absorb stains
Metal ceramic crowns contraindicated :
• When the patient desires perfect aesthetics
Disadvantages :
• High cost
• After a while, some time, because of the age or traumatic brushing, seems cervical the metallic frame and the patient complaints that the teeth is «grey».
• Needs a special handling for perfect fit
The procedure is the following :
1st visit :
• Color measurement with SpectroShade™ Micro
• Taking initial dental impressions with trays and impression materials for preparing the temporary crown
2nd visit :
• Local anesthesia
• Reduction of the volume of the tooth –tooth preparation
• Temporary crown placed
3nd visit :
• Removal of the temporary crown
• Final preparation of the tooth
• Taking final dental impressions
• Temporary crown replaced
4nd visit :
• Removal of the temporary crown
• Probing the metal base of the dental crown
• Temporary crown replaced
5th visit :
• Removal of the temporary crown
• Probing of the dental crown with porcelain which is not finally polished
• Temporary crown replaced
6th visit :
• Removal of the temporary crown
• Permanent cementation of the dental metal ceramic crown
