Dental prosthesis is that branch of dentistry that deals with the treatment of patients suffering from the lack of one or more dental elements and with problems with adjacent tissues. These are real artifacts made by qualified dental technicians, under the guidance of the dentist, able to replace the original dentition lost or compromised for functional and / or aesthetic reasons. The prostheses can be fixed – such as crowns, inlays and bridges – or removable.
The fixed prosthesis can be built both on bone implants and on natural teeth. The materials that are used vary a lot, depending on each case: resin, metal-resin, metal-ceramic, all-ceramic.
The prothesis must be adequately integrated from the biological point of view respecting both the gingival tissues and the pulp organ during the phases of dental preparation, impression taking, provisional positioning and cementation of the restorations.The loss of dental elements or the lack of reliability of existing natural elements leads the clinician and the patient to choose prosthetic solutions anchored to osseointegrated implants, which can effectively replace these missing elements. During any prosthetic rehabilitation, whether limited to an area of the oral cavity or extended to the entire mouth, it will be fundamental for the maintenance over time of the restorations to carry out a periodic and scrupulous monitoring of the performed rehabilitation, as well as a careful and systematic control of the oral hygiene of the patient.
Causes of a missing tooth:
- The dental element had been extracted because it was heavily attacked by caries which resulted in pulpitis not treated in time and the patient decided to replace it with a bridge;
- – due to the traumatic fracture (accident) not only of the crown but also of the root of the tooth;
- important dental abscess;
- old age;
- severe periodontitis which determined the instability of the dental element that the dentist had to remove.
Why replace the missing tooth?
- To restore correct chewing;
- to prevent the movement of adjacent teeth causing malocclusions;
- to restore the aesthetics of the patient who would feel uncomfortable in his social life;
- in the case of dental implants, it helps to significantly delay bone regression.
Dental crowns are fixed prostheses made of various materials:
- ceramic (pure porcelain)
- metal-ceramic (alloy-ceramic)
- resin (usually they are temporary crowns)
When are dental crowns recommended?
- When the teeth are filled with caries, they are chipped or broken and cannot be reconstructed with fillings;
- when the teeth are devitalized, because after devitalization they become weaker and can be damaged;
- when the teeth are affected by diseases that are destroying the enamel;
- when we need to cover an implant.
Modern crowns replace the old metal crowns that used to have the huge disadvantage of the lack of translucency on the gingival level, since the rays of the incident light were blocked by the presence of the underlying metal unlike the natural tooth and this, even in well executed crowns caused frequent imperfections.
The capsule-tooth finishing area also consisted of a metal border, often covered with an opaque material, which shined through the gum ruining the naturalness of the smile. These problems, associated with the ever-increasing aesthetic needs of our age, have nowadays led to the production of crowns in full ceramic or in zirconium which have made it possible to obtain excellent results precisely because without being associated with a metal core they reproduce the transparency of the natural tooth.
Before proceeding with encapsulation, the tooth is prepared. Tooth preparation includes the following steps:
- when required the tooth is devitalized, to avoid suffering and pain;
- subsequently the tooth is sanded, until obtaining the necessary thickness for encapsulation (obviously the part of tooth removed will be equal to the thickness of the crown to be mounted);
- the staff take the impression, choose the color and proceed with the preparation of the artificial crown;
- the last step would be the cementation of the final dental crown (if a temporary crown has been applied in the meantime). The crown can be cemented with a specific dental cement that also acts as a sealant to hold the crown firmly and firmly.
The treatment is painless. The crown will be made so as to look the same as the other teeth and the color of the neighboring teeth will be used to make the crown fit as naturally as possible between the other teeth.
A temporary crown, normally made of plastic material, will be mounted on the prepared tooth until the final crown is ready. These provisional ones may be less natural than the final crown and therefore may be noticed more but we must remember that they are made to last only a few weeks.
The dental bridge is a fixed prosthesis used to replace one or more teeth that are missing for different reasons. To restore optimal masticatory function and aesthetics, dentistry offers two solutions:
- a bridge supported by adjacent teeth that act as pillars;
- a crown on an osseointegrated dental implant that serves as an artificial root on which to secure a prosthetic crown.
It is up to the dentist to evaluate each specific case and tell the patient the advantages and drawbacks of the two dental procedures.
Unlike the implant, which involves inserting a screw into the gingival bone with an artificial tooth on it, the bridge is an artificial tooth with no root, which is placed directly on the gum where the natural tooth used to be. The dentist then fix it to the adjacent teeth.
What is the procedure for applying a dental bridge?
During the first visit, the abutment teeth are prepared. The preparation involves a recontouring of these teeth by removing a portion of enamel to make room for a crown above them. Subsequently, the impression of the teeth is taken so as to have a model from which the bridge, the intermediate element, and the crowns will be created by a dental laboratory.
Then the staff creates the temporary restoration that is going to be able to immediately give comfort and protection to the teeth and gums exposed, while the final bridge is being prepared.
Furthermore, the temporary restoration allows to model and condition the gingival shape and to preview the final result: the definitive work is actually a copy of the provisional.
Subsequently, a precision impression is taken, which is later delivered to the dental technician to carry out all the necessary aesthetic and functional tests. The bridge can then be cemented.
Multiple visits can be made to check the adaptation of the metal structure and especially the bite.
Remember that dental bridges require scrupulous home hygiene. To avoid periodontal diseases and caries, the patient should accurately brush the gingival edges as well as the space under the bridge; moreover, the area where the bridge is located must also be cleaned by passing a specific dental floss – superfluous – in order to prevent food residues from triggering infections, abscesses, inflammation or any pathological process.
The inlays have substituted the old amalgams, that is the gray dental fillings, the so-called sealants that besides having a very bad aesthetic impact, contain 50% of mercury, a gram of which is sufficient to contaminate 20,000 kg of food (current EEC legislation).
The danger of old dental amalgams consists essentially in a chronic exposure to low levels of mercury that affects the brain, the thyroid, the bone marrow, the kidneys, the liver, the heart and other tissues, according to recent epidemiological studies.
The inlays are in fact composite or ceramic fillings, performed in the laboratory, which are then cemented into the cavity of the tooth, previously prepared.
They are used for the posterior teeth (premolars and molars) where it is easier for the cavities to be large. The tooth is prepared as for a filling that, instead of being carried out by the dentist, is performed by the dental laboratory on a precision impression. The inlay is then cemented.
Today the use of composite or integral ceramic inlays represents the opportunity to limit the invasiveness of restorative methods, maintaining the margins of the restoration out of the gingival sulcus and effectively restoring the biomechanical characteristics of the treated elements.
The inlays have a very high aesthetic output, they last over time and the point of contact between inlay and tooth is extremely precise.