Three weeks after insertion of FPD marked discomfort to heat and cold occurs
there are no other symptoms the most likely cause is:
- A- gingival recession.
- B- unseating of FPD. (Will cause pain on chewing)
- C- deflective occlusal contact
- D- torsional forces on the abutment tooth
- E- incomplete coverage of cut surfaces of prepared abutment teeth.***
In dentistry, the crown is the part of the tooth which exceeds outside the gum (as opposed to the root). This area is naturally covered by a very hard substance, dental enamel.
The term crown also designates by extension the prosthetic crown, a dental prosthesis making it possible to protect a tooth which is alive or not (devitalized). It covers the part of the remaining tooth by reconstructing the coronary part, which preserves the tooth of new attacks, while avoiding its extraction and its complete replacement.
It also happens that patients require an extension of the crown to improve the aesthetics of the smile, in order to reduce a gingival smile.
Types of crowns:
It can be in ceramic, chrome-cobalt, nickel-chrome, or precious metal. All-ceramic crowns (ceramic on ceramic or zirconia screed) as well as those made of precious metal or titanium offer the best guarantees against the risk of allergies.
Nickel-chrome does not provide the same guarantees. Thus, for the restorations of teeth made of nickel-chrome, a black tattoo, which is not very little aesthetic, can appear on the gum in contact with the alloy. Surgery alone can overcome this problem and deposit the crown will not be enough.
For anterior teeth, the dentist poses for aesthetic reasons of ceramic or ceramalalical crowns (knowing that over time a metallic border appears at the level of the gum). For posterior teeth, the aesthetic incidence being less important, the dentist often poses for financial reasons of metal crowns. Ceramic or zirconia crowns are slightly translucent, which gives them a more natural effect.
Ceramo-metallic crowns are thicker than all-ceramic or zirconia crowns. They therefore require to file a larger part of the tooth to be placed on it, which sometimes requires devitalizing the tooth.
Reasons for setting up a crown:
Dimantement of the tooth:
When a dental cavity is small and the tooth is not too dilapidated and that after cleaning the cavity by the dentist, the structure of the tooth is sufficiently important, the dentist fills the cavity with an amalgam, a resin or a composite. But, when the cavity is important, that it does not remain enough dental structure and the tooth is fragile or that the tooth is fractured, the restorations seen previously are not possible: the restoration of the tooth requires the installation of A crown or an onlay.
Devitalized tooth:
A tooth having benefited from endodontic treatment (or devitalization) is said to be devitalized, that is to say that its pulp containing the nerve and the vessels, has been removed and the cavity formed has been properly cleaned and filled to avoid any Invasion of bacteria later.
Following this treatment, there is generally not enough tooth to carry out an amalgamation as in the case of a simple caries. In addition, devitalization has made the tooth much more fragile and brittle compared to its living neighbors: the tooth risks fracturing vertically or later and it will certainly be necessary to extract it. To avoid this, the dentist covers the devitalized tooth of a prosthetic crown.
The risk of devitalized teeth fractures increases considerably on posterior teeth when a crown does not protect them. Indeed, an average person exerts a significant muscular force on these posterior teeth which is approximately nine times higher than that exerted on anterior teeth. If the effective posterior contact zone is 1 mm2, then a pressure of more than 7.109 PA is exercised on the restoration.
This is why posterior teeth (that is to say molars and premolars) must, in virtually all situations, be crowned after having suffered a devitalization in order to protect them from fractures.
