A crown is actually an artificial replacement for the natural crown of the tooth that has been ruined, it is like a wrapper that covers all sides of the tooth, in order to restore its size, shape, function
When is it necessary to make a crown?
Most cases requiring a crown are: After a root canal treatment (because the tooth is no longer capable of spreading the chewing forces and in most cases the tooth fractures after then and mostly cases when it is happening we must extract the tooth, another case when the tooth has been fractured or traumatized and has no root canal treatment, and cannot be reconstructed in any other way just by crown, and it is made also to correct. aesthetic or functional problems.
Different types of crowns:The crowns can be made just of metal, combined with metal and white plastic material, porcelain, zirconia, or even without metal just plastic, porcelain or zirconia. each type of crown has different advantages and disadvantages, from the medical or financial point of view. In the situation that a crown is needed I recommend to the patient what kind of crown is preferable in his case.
Different types of metals used in crowns.
They can be of precious metal, semi-precious or non-precious basic metals. Each of these metals has its strengths or weaknesses in relation to the qualities of the metal both physical and biomechanical these alloys composed of several metals can provide the most optimal result during the crown manufacture and after its installation in the mouth through the years without causing problems.
Precious metal: This group, of course, is composed of gold, palladium, platinum, silver.
Pure gold is the best metal for use on the mouth and teeth, has excellent properties around the tooth and gums and prevents plaque formation, so bacteria cannot live near it. Precious metal alloys used in dentistry are a mixture containing gold, palladium, platinum, silver must be at least 60% precious metals and at least 30% gold. Due to the high cost of hundreds of dollars its use today is less common.
Semi-precious metal. It is an alloy of precious metals at least 25% to 40% and most metals are not precious,
Non-Precious basics metals: alloy of non-precious and precious metals in very small percentagesor null. Among the basic metals are cobalt, chromium, widely used dentistry
The priority is to use precious or semi-precious metals and finally the alloys not precious from the medical point of view but about to the resistance and the physical properties when these are covered with porcelain is contrary because the precious metals will produce a more flexible crown to the effect of traction that would cause a fracture in the porcelain therefore, the choice of the type of metal for each crown is determined by the dentist.
How is the procedure performed?
1)tooth shaping in different thicknesses of all the sides of the tooth according to the type of crown to manufacture between 0.3 mm to 2 mm.
2)Take an impression to build the crown in the laboratory
3)placement of a temporary acrylic crown until the work is finished.
4)Measure and test the metallic base of the crown
5)Receive the crown and cement it to the tooth
Different types of crowns
Acrylic crown / temporary plastic. This plastic crown called acrylic is used for decades in dental practice. Its production can be in the clinic with cold acrylic or in a laboratory with hot acrylic that must be cooked. it is very important to place a temporary crown until the process of manufacturing and subsequent cementation has been achieved, and is to protect the tooth stable and fixed without the possibility of movement which will make the final crown and tooth be precise, protect the gums, restore function and esthetics provisionally, until the installation of the crown. The disadvantages are: very fragile material, and the sealing is not good around the tooth, irritation of the gums causing damage because of the use of acrylic in the long term, therefore it is only for temporary use.
A fully metallic crown: a crown that requires minimal tooth shaping. Usage is usually on the posterior teeth due to space limitations and the possibility of shaping, or avoid unnecessary damage to teeth that do not have root canal treatment. It may be from any of the metals mentioned above. It is less common today because of its poor aesthetics
Porcelain-only crown without metal, suitable for anterior teeth only, reflection of light is similar to the tooth. Therefore, here lies its disadvantage because there are traumatized teeth or after a root canal treatment and they suffer a blackening, and the result end will be a dark reflection of the tooth giving an unsightly gray color. It requires high skill of shaping for the dentist and also for the technician in the laboratory that is more difficult to obtain. In addition, the tendency to a lack of sealing in the margins of the crown that produces the appearance of caries. Today its application is very rare
A total zirconia crown: a pure zirconia crown. Zirconia is actually a metal called zirconium which is white gray, a material very resistant to fracture and corrosion. Therefore, the material is very suitable for use in the mouth.The manufacturing process is computerized where a drill shapes a block of white zirconia made of zirconium powder. The final product is a strong and unbreakeable white metal crown, even in fine thicknesses and which transmit the light in a similar way to the tooth.
Disadvantages. It costs more than 50% of a porcelain or other metal crown. Due to its reflection in the dark anterior teeth will result a bad aesthetic and a grayish color. Another disadvantage is that there is currently no suitable cementing material and its attachment to the tooth is not good enough to prevent its detachment from the tooth. Very suitable for use on posterior teeth due to limitations of space or shaping.
Porcelain crown fused with metal: The base of the crown is made of metal can be any type of metal mentioned above, and on it is fused porcelain at a temperature higher than 1200 ° C. This is the crown mostly used in dentistry from the point of view of the dentist and dental technician, who demonstrated its aesthetic and functional durability for many years.
What is a bridge?
This is actually at least three crowns that are joined by forming a bridge between two teeth pillars when there is a missing tooth between them. This is a permanent rehabilitation to replace a missing tooth. It requires the shaping of the teeth adjacent to the missing tooth. The bridge may be of the same material as the crowns (see above) and the procedure is similar to the crown
Adhesive Composite resin bridge: Today there is also a technique that can be used to join two teeth in a single session without needing to shape the adjacent teeth of the missing tooth by connecting the adjacent teeth with a transparent strip and building the missing tooth in the same band. It is especially indicated to be used in the anterior part, but it can be done anywhere in the mouth. and is suitable for the rehabilitation of a single missing tooth. the disadvantage is that sometimes it does not withstand the pressure of chewing, it finally leads to failure and it should be re-made or choose other options that support the forces of mastication and are more durable. Because of this in the posterior area less is used. There are not many dentists who do this type of resin rehabilitation as it requires great skill and the technique of application is complex