DENTAL CROWNS AND BRIDGES

Simply stated, a dental crown is a tooth cap placed to cover the tooth to restore its shape, its size and its strength. A bridge is a combination of crowns.

A dental crown may be advised to:

  • protect a weak tooth (for instance, from decay) from breaking especially after an RCT
  • restore an already broken tooth or a tooth that has been severely worn down
  • cover and support a tooth with a large filling when there isn’t a lot of tooth left
  • hold a dental bridge in place
  • cover misshaped or severely discolored teeth
  • over a dental implant

 

Dental bridges are meant to replace missing teeth by “bridging” the gap between two remaining teeth. This involves creation of a pontic, or false tooths with a dental crown on either side. The crowns are fitted over the remaining teeth to hold the false tooth in place.


When there are only teeth on one side of the gap, cantilever bridges may be given. cantilever bridges consist of two side-by-side crowns and only one is connected to the pontic.

A fixed bridge helps to

Replace missing tooth/teeth.
Helps balance a normal bite.
Helps prevent undesirable stress on the dental ridge.
Prevents over-eruption of the opposing teeth.
Prevents drift and tilt of adjacent teeth.
Prevents tooth decay in adjacent drifted teeth
Retards onset of gum diseases

To design a bridge, the dentist must reshape the teeth to make room for the crowns. The dentist then makes a mold of the teeth. This mold is then sent off to a laboratory, where the actual crowns and bridge are made.

These crowns and bridges require a bit of extra care in terms of oral hygiene. With such care, bridges can last up to several years. However, improper or infrequent brushing and flossing, irregular dental visits, and excessive sugar and starch intake can all bring untimely damage to the bridge

MATERIALS FOR DENTAL CROWNS AND BRIDGES

All Resin – These are the least expensive crowns. Today these are generally used for temporary or provisional coverage. But like most inexpensive things they do not last as long as other types of crowns.

Metals – These could include gold alloy and other base metal alloys. Metal dental crowns are by far the toughest. They can withstand daily wear and tear and they rarely break or chip.

A gold crown has some very distinct characteristics that make it a good choice
1. Gold Fits better : A well-cast gold crown fits considerably better then other materials. Because it fits better, it lasts longer! The bacteria we all have in our mouths have less access to the micro-margins.

2. Gold Is Strong And Flexible : Gold expands and contracts at the same rate as your natural tooth. This protects the gold crown from chipping, cracking or breaking; which can be a problem with other less versatile materials.

3. Gold Is Safe And Comfortable : Gold doesn’t just look good–it feels good–because gold is remarkably compatible with the inside of your mouth. With many other metals, the likelihood of sensitivity or an allergic reaction is a significant risk for the patient. But not with gold.

 

 

However not all crowns with the color of gold are the same – The best of the dental gold is an alloy of many metals, (gold, platinum, palladium, silver, copper and tin) and are usually about 76% gold or a little over 18 carat. Some gold crowns are made of an economy gold and are only gold in color and don’t possess the casting characteristics so important for a good seal at the edges. These cheaper gold-content crowns are on the order of ten carat and do not have the tissue tolerance and compatibility of a higher gold-content alloy

Indications:

Worn out teeth where creating additional space for porcelain is not possible.
Posterior teeth where esthetics are not the prime concern

The only real drawback is that they look like metal and not a naturally white tooth.

Metal-Porcelain –

They combine the strength of the metal along with the esthetics of porcelain. These are probably the most used crowns nowadays. Of course the porcelain is slightly more prone to chipping, but they are still tough.

There are different types of porcelain fused to metal dental crowns :

There is a choice in the metal
1. Precious alloy (89-92% gold alloy, yellow gold color)
2. Semi-precious alloy (54-62% gold alloy, “white gold”)
3.   Non-precious (metal alloys, stainless steel color)

 

 

 

 

Precious alloys with high gold and platinum content are most preferable. One such crown that is commonly used today is called Captek .

 

 

 

Captek is an 88% gold alloy, which uses a unique fabrication system to provide the most extreme combination of strength and esthetics. It is formed using capillary casting technology which provides its exceptional characteristics. Due to porcelain’s translucency, Captek crowns are truly the most beautiful metal-based crowns and are highly recommended for all areas of the mouth, front or back.

The advantages of using Captek are many;

Biocompatible: Captek’s advanced gold material reduces the accumulation of harmful bacteria at the gum line by 90% compared to natural tooth structure.Superior fit: Captek fit is superior to all other restorations, This is due to the fact that there is virtually no expansion or contraction, as there is no casting of the metal.

Esthetics: CaptekT (capillary technology) offers patients the beauty, health and longevity of gold crowns and bridgework Because it is a high gold alloy, Captek can impart a natural hue to porcelain veneered crowns and bridges. The light-dispersion effects of Captek crowns are designed to mimic those of healthy natural tooth structure. There is no oxidation, so it will not lead to black lines at the gum margins

It can easily be used for single crowns, implants, and bridges both anteriorly and posteriorly.

The only reason we have gone away from gold under our porcelain fused to metal crowns is the high cost of gold.

Semi-precious metal offers a balance between esthetics and strength at a lower cost than precious metals. It resists oxidation, it casts more accurately than non-precious metal, and it is a very commonly chosen option. But it cannot provide the warmth and beauty of gold-lined porcelain crowns.

Non-precious alloys are made of low-cost metals and have been in use for many decades. They are more difficult to cast (shape) than softer precious metals and therefore offer a less precise fit. Non-precious alloys also tend to oxidize over time) which darkens their color even more and can even stain and “tattoo” the gum.

All Ceramic Crowns and Bridges (Metal Free ceramic crowns)

These are the best looking crowns, and probably the best value for your money as far as esthetics are concerned. Contrary to what might appear, these materials are extremely strong and fracture tough. The material can well sustain the masticatory forces, providing durable crowns and bridges with beautiful esthetic results. They can be conveniently and reliably used in any part of the mouth. These are also the preferred material of choice in patients with metal allergies. Metal free restorations are produced with the latest CAD/CAM technology ensuring precision of fit. Some well known Metal free systems used are