PFM Crown

Introduction

Dental crown is a cap placed over a tooth for restoring its shape, size, strength and also for improving its appearance. These crowns totally enclose the visible part of the tooth lying above the gum line after cementing.

Indications for a Dental Crown:

Dental crown is needed in the following conditions:

• For protecting a week tooth from decay, from breaking or for holding parts of a cracked tooth.

• For restoring broken or severely worn out tooth.

• For supporting and covering a tooth with large filling.

• For holding a permanent dental bridge between abutment teeth.

• For covering a dental implant

The porcelain fused to metal crown:

This crown consists of a metal core inside and a layer of porcelain outside blended together. PFM crowns look just like normal teeth.

The metal in this crown provides strong compression and tensile strength, which makes it suitable for back teeth (molar) restorations. The porcelain material in the crown gives a white tooth-like appearance, suitable for front teeth restorations. This restoration can withstand extensive biting stresses.

Making of porcelain fused to metal crown:

The shade of the crown can be matched to the color of existing teeth, unlike pure metal. In the dental laboratory, the noble metal alloy base is heated to very high temperatures in an oven and it is fused with several layers of porcelain. Porcelain can be fused to metals like platinum, palladium or even gold as well. But for using gold, there should be presence of enough healthy tooth structure. Using gold means the toughest material and can last for a longer period than any other metal. These crowns can also be made with a partial veneer which covers only the visible aspect of the crown.

Tooth Crown Procedure:

• The cosmetic dentist prepares an impression of the tooth and sends it to a dental laboratory to make the permanent crown.

• A temporary crown is given to the patient to wear till the permanent crown is ready.

• After about two weeks, generally the crown is ready and the permanent crown is then cemented onto the tooth. Thus, only two visits are required for this procedure.

• For stabilizing this structure, a filling is placed before placing a crown due to the loss of original tooth structure. Dental crowns have a running life of ten to fifteen years.

• Make sure to discuss with the dentist about the color of the crown and also check whether it is same as temporary crown.

• Sometimes, a Flipper appliance is used in the place of temporary crown till the permanent crown is placed. A Flipper is a false tooth attached via either a wire or a plastic piece to the roof of the mouth awaiting the permanent crown.

Advantages:

• The shade of the crown can be matched to the color of existing teeth, unlike pure metal.

• Most natural appearance of teeth than any other dental bridge material.

• PFM bridges can be used for both front as well as back teeth.

• They are durable and have enough strength due to metal core.

• High success rate for long-term use.

• They can be used as a single unit or as a part of a bridge.

Disadvantages:

• The porcelain on the surface can wear the tooth that bites against it.

• They are more vulnerable to chipping and breaking than pure metal.

• The PFM crown requires more of the healthy tooth structure to be removed because of its thickness.

• Porcelain’s translucence sometimes allow the inside metal core to show through.

• A dark blue line is visible above the gumline due to metal core.

• There are more problems at the gum line, especially if the gums recede with time or there is gingival inflammation.

The porcelain fused to metal crowns have a running life of about 10 to 15 years if proper care is taken and regular oral hygiene practices are followed. People having porcelain or metal allergy are not suitable for this crown. The crown should be replaced if it breaks or falls off.