Dental Crown

[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

A dental crown is a restorative oral prosthesis, similar to a cap, and that is shaped and made to look like a real [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]. A crown is usually placed over a tooth that was damaged by either [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط] or by a fracture, to cover and protect it by reconstructing its shape, its exquisiteness, its size and its strength.
Once cemented, a dental crown completely covers the portion of the tooth which is above the [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط].
Porcelain is the material that is mainly used to make a crown because
of its aesthetic qualities, with visual properties that are very
similar to dental enamel. Therefore a crown looks like a real tooth in
its shape and colour.



Reasons why crowns are necessary



[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

A deteriorated tooth, which requires a dental crown, may be alive or devitalised by a [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط].
If the tooth is alive, it would need a crown if it previously had a big
cavity or a fracture that was maintained far enough from the [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط] (nerve). There are several reasons why a tooth would need a crown:

• To protect a weakened tooth (by tooth decay for example) against rupture, or to keep together a cracked tooth.
  

[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

• To restore an already broken tooth or a severely worn out tooth.
  
• To restore a tooth that has had a root canal and a post.
  
• To cover and support a tooth that had a large [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط] when there isn't enough healthy tooth structure left to be restored by a new filling.
  
• To cover a tooth that is malformed or severely [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط].
  
• To cover a [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط].
  

Types of crowns



Several
materials can be used to make a dental crown. There is no universally
ideal material. The choice depends on many factors including the
location of the tooth and the aesthetics that are required.


[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

A crown made of gold alloy
is the one that lasts the longest. It resists very well to chewing
forces, it rarely breaks, and it causes very little wear to opposing
teeth. The gold's metallic colour is the main disadvantage of this type
of crown and this factor reduces its popularity. However, gold would be
a good choice for a molar that does not appear when a person smiles.
Gold crowns are made in a laboratory with an impression that the
dentist takes of the tooth; it is therefore necessary to protect the
tooth with a temporary crown during this period of a few weeks.



[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

A crown made of porcelain fused to gold
is a more aesthetic crown than the one made of gold alloy. Porcelain
can make a crown look very similar to a natural tooth. The gold part,
which is located below the porcelain, helps give strength to the tooth.
Porcelain is very strong, but is less strong than gold and can
fracture. Sometimes the gold under the porcelain may show, especially
at the gum level. This type of crown is also fabricated in the
laboratory with an impression of the tooth, and a temporary crown is
needed during that period of fabrication.


[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

An all ceramic
crown is the most aesthetic crown because it is made of porcelain only.
Its shape and colour can match the qualities of natural teeth very
closely. This crown is however less solid than gold crowns or porcelain
fused to gold, although new varieties of porcelain which are more and
more resistant are coming out on the market. Porcelain only crowns are
recommended for anterior (front) teeth to favour beauty and offer a
better looking smile. Porcelain crowns are generally fabricated in a
dental laboratory.
A CEREC crown is also
made of porcelain only. This technology allows the dentist to engineer
himself the crown following an electronic impression. The design and
preparation are assisted by computer. The great advantage of CEREC is
that a second appointment is not required to install the crown after
its making in a dental laboratory since CEREC technology ensures the
production of the crown in a few minutes by the dentist himself. But
even though CEREC's porcelain is becoming more and more beautiful,
dental laboratory's porcelains are still more aesthetic and resemble
more the natural appearance of teeth.
A temporary or
provisional crown is made by the dentist himself and has a lifespan of
a few weeks. It is made of acrylic or stainless steel, and serves as a
temporary restoration until the permanent crown is made by a dental
laboratory. A temporary crown is not strong and can break easily.




Steps to prepare a crown



Before
starting any treatment, the dentist must examine the tooth which needs
the crown as well as its x-ray. He or she must determine if there is a
cavity present, and whether the tooth previously needs a root canal.
If
a root canal is necessary, it must be made first. A root canal also
allows placing a dental post on which the crown will hold. If the root
canal treatment is not necessary, any cavity should be removed and any
old fillings should be replaced on that tooth.
The preparation of a crown is conducted over two appointments at the dentist:

• During
  the first visit, the dentist shapes the tooth by reducing it slightly
  all around to create space for the crown. An impression of the tooth is
  taken to be sent to the dental laboratory where the crown will be
  prepared. A temporary crown is then placed on the tooth which will
  remain there until the following appointment.
  
• The second
  visit is usually shorter and takes place two to three weeks later in
  order to cement the permanent crown. The dentist removes the temporary
  crown, checks the adaptation and colour of the permanent crown before
  installing it with dental cement.
  

A crown of the
CEREC type needs less dental appointments since the engineering of the
crown is done at the dental office and does not need to be sent to a
laboratory.



Care for a temporary crown



[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

A
temporary crown (or provisional) lasts only a few weeks pending the
construction of the permanent crown at the laboratory. It is less
robust and requires some care so that it does not break:

• Avoid sticky foods like caramel or chewing gum, which can dislodge the temporary crown of the tooth.
  
• Avoid hard foods that could fracture the temporary crown.
  
• Try not to chew on the side of the mouth where the temporary crown is placed.
  
• If the temporary crown falls or breaks, do not panic, but call your dentist to warn him.
  

Lifespan of a crown



A
dental crown can last between 5 and 20 years. The lifespan depends on
oral hygiene, oral care, oral habits, and the material used for the
crown (gold versus porcelain). [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط], chewing on ice or biting your nails are conditions that can brake down a crown or even make it fall.

If
a crown falls out from the tooth without breaking, it can simply be
cemented back in its place as long as the tooth does not have any
cavities. If a crown has a major fracture, it should ideally be
replaced. A minor fracture can sometimes be repaired by the dentist.


Maintenance of a crown



It's important to remember that even though a crown cannot be decayed, the tooth below may be exposed to cavities and [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]. Good oral hygiene care should be preserved including tooth brushing and flossing.
During [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط],
your dentist checks the state of the tooth, the state of the gums, the
condition of the crown and its adaptation. It is recommended to go for
regular dental checkups every six months to verify the general
situation of the mouth and teeth.

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السلام عليكم
بارك الله فيك على هدا الموضوع
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ويرية انحصلو اكتر معلومات حتى فى المواد الاخره :lol: