When a natural tooth is severely compromised, or when teeth are missing along with adjacent ones that also need protection, crowns and bridges are a valid solution to restore aesthetics and function.
Fixed prosthetics function is to protect or to replace lost or compromised teeth for functional and/or aesthetic reasons, when implantology, which remains the best solution in terms of biological preservation, is not desired or possible.
Dental prosthetics refer to the branch of dentistry that deals, with the aid of dental technicians, in the design and construction of prostheses, adhering to the following requirements:
Functionality: involves restoring proper chewing and joint functions (opening, closing, right-left lateral movements, protrusion-retrusion, and proper phonetics).
Durability: the prosthesis must withstand masticatory loads and wear.
Biocompatibility: the prosthesis must be made of non-toxic materials and should not have sharp angles that could damage tissues, causing long-term serious lesions or pathologies.
Aesthetics: artificial teeth should resemble natural ones as much as possible, and care must be taken not to alter the correct facial profile of the patient.
They are applied to the teeth prepared by the dentist, reducing them in height and volume, and the prosthesis is cemented onto them, presenting the same shape and function as the natural tooth.
A crown is used to cover a single tooth. The reason for covering a tooth with a crown is to preserve its integrity when it is weakened or at risk of fracture. This can result from root canal treatment and/or a large reconstruction of the tooth, making it more susceptible to fracture in the event of accidental occlusal trauma.
A bridge is used when a tooth is missing, and the teeth in front and behind are used to create a “bridge” that will replace the missing tooth with an extension element. This procedure involves the need to “file down” the other teeth, thus reducing their size and possibly performing root canals. If this intervention is carried out on already partially compromised teeth, it may be appropriate or advantageous. However, if the adjacent teeth are healthy and intact, the cost/benefit of this procedure should be carefully evaluated as it compromises the anatomical integrity of otherwise healthy elements. Finally, it is worth remembering that prosthetic and covered teeth are mechanically protected but not from the risk of cavities. A prosthetic tooth can be at higher risk for cavities, so in the presence of bridges or crowns, oral hygiene management must be even more careful and meticulous.
Metal-Resin Crowns and Bridges
These have a structure made of a noble dental alloy inside, coated with an opaque layer and composite resin that is properly shaped and hardened at temperature and under pressure to give the material greater compactness.
Metal-Ceramic Crowns and Bridges
These have a structure made of a noble dental alloy inside, coated with an opaque layer to prevent the metal color from showing through, and ceramic is layered over this and baked in specific ceramic furnaces. The high temperature transforms the earthy mixture into a vitreous substance that is very hard and resistant to abrasion and mouth acids. Among the advantages of ceramic, the most important is its stability in shape and color over time.
Temporary Resin Crowns and Reinforced Resin Bridges
These are fixed to the tooth or implant during the processing period of the definitive crown or bridges or while waiting for any healing. Even though they are temporary, the functional value of a temporary crown or bridge is very important. The temporary crown is necessary to protect the tooth from thermal stimuli when it is not devitalized but has been filed down, i.e., dimensionally reduced, before final prosthetics. It also serves to protect the tooth from bacteria that can penetrate through open dentinal tubules, causing inflammation of the nerve (pulpitis), to avoid discomfort while eating during the treatment period, and to prevent tilting due to lack of contact points. The temporary crown also helps prevent excessive growth of the gingival margin around the filed tooth. In the case of multiple filed teeth and to withstand masticatory forces for a long period, temporary crowns can be reinforced with a metal structure: in this case, it is called a reinforced temporary crown.
All-Ceramic (Metal-Free or Zirconia) Crowns and Bridges
These prostheses have no metal structure inside, so there is no edge that becomes visible and unsightly in case of gingival recession. Zirconia is a very abundant mineral in the soil, derived from zirconium oxide called zirconia, a very strong, biocompatible material that causes no allergies. It excellently replaces any type of prosthetic metal, both aesthetically and functionally, and can be used to make all types of dental prostheses: crowns and bridges of all sizes, screwed (implant abutments) or cemented, on natural teeth or oral implants.
Ceramic Veneers
Today, it is possible to correct small misalignments, discolorations, or crown imperfections of the front teeth without necessarily undergoing prosthetic treatment that involves reducing the tooth’s volume. The preparation consists of reducing a couple of millimeters of the anterior and occlusal surface of the teeth and, after treating the surface, thin layers called veneers, made of ceramic material, are applied. These veneers are prepared in the laboratory from an impression of the patient’s teeth. The result is exceptional. The only risk with this type of solution is that, since the veneer is bonded to the surface of the treated tooth, it can “detach,” causing significant aesthetic discomfort.
