The following information takes into account dental prosthesis constructions, such as crowns, bridges, partial dentures and total restorations, as they frequently occur, both on natural teeth and on artificial tooth roots. Special features of dental prostheses in the esthetic zone
Crowns and bridges
Technically speaking, crowns are rings that are usually used to hold damaged tooth substance together and/or as anchors for fixed and removable bridges or partial dentures. Accordingly, bridges are constructions to replace one or more teeth, in which the missing tooth parts are firmly connected to the artificial crowns. Crowns can partially (partial crown) or completely (full crown) replace the original enamel. Fixed crowns are cemented or glued, therefore they are not removable for the patient.
For the production of crowns, the supporting teeth must always be reduced in volume to the extent corresponding to the thickness of the crown layer. For this purpose, the tooth is ground and a model is obtained (via an impression of the teeth), which is used for further laboratory steps. The time required is between one and three weeks, depending on the effort required in the practice and in the laboratory. An alternative method is to digitize the defect, as can be done on the patient in reconstructions made of milled ceramics.
In the age of all-ceramics crowns with ceramic shoulders and galvanic crowns are rather rare.
With ceramic shoulders, a cast metal framework is cut back in the neck of the tooth, i.e. at the transition to the untouched root, in order to achieve aesthetic optimisation. These crowns lack the metal edge, so that the illusion can be created that the crown comes “as grown” from the gums. The fabrication of ceramic shoulders requires several separate steps: a more precise preparation (use of magnifying glasses), because the model has to meet higher requirements, and a separate firing of the ceramic in the laboratory, because the self-supporting shoulder must first be fabricated before the actual veneering becomes possible.
Galvanic crowns differ from “normal” cast crowns in terms of their metallic substructure. Whereas in conventionally cast crowns the shape of the future metal is modelled in wax and corresponds to the casting technique for church bells, the pure gold layer of electroplated crowns is applied to the die model in the electroplating bath.
All-ceramic partial crowns (veneers), all-ceramic crowns and all-ceramic bridges:
All-ceramic forms of care are used for patients with increased aesthetic requirements and for patients with allergies to metals.
Adhesive bridges – bridges without crown anchors:
Adhesive bridges (“Maryland” bridges), mostly used in adolescents who want to preserve the tooth substance, are glued to the anchors (teeth) from the inside via small wings. They serve as a very long-term temporary solution, but can also be used as a temporary solution in the context of implant treatment during the healing phase.
Removable bridges are special constructions that combine the advantages of the Grazility of fixed bridges with those of the ability to reconstruct removable partial dentures. In principle, removable bridges are similar to fixed bridges in shape and appearance, the only difference being that they are not cemented to the teeth but instead are placed on an additional intermediate crown in the form of a cylinder.
The inner crown can consist of a ceramic (first example) or a metal alloy, is firmly attached to the tooth and the actual bridge is placed on this substructure. Removable bridges are only removed for cleaning, they can also be veneered with ceramic materials. Construction elements such as saddles covering the mucous membrane and palatal plates or undertongue brackets are often completely missing.
Removable bridges are particularly suitable for periodontally weak teeth and/or the connection of one’s own teeth with artificial tooth roots (dental implants).
Ceramic inner crowns, non-precious metal constructions and ceramic veneers are special forms. Please do not hesitate to contact us.
Removable partial prostheses
Partial dentures are tooth replacement constructions in which not only teeth but also gums and jawbones are replaced. They are characterized primarily by plastic saddles, which almost always still have connections to the opposite side of the jaw. The plates and temples are made of metal. The remaining teeth serve as anchors and ensure the stability of the construction. Partial dentures have the great advantage of being easy to rebuild in the event of tooth loss, but due to their construction they are always much larger than the row of teeth alone.
Clasps, double crowns, attachments, anchors and others are used to anchor teeth or crowns. In the case of partial dentures, implants can be used to increase the number of supporting teeth.
Total dental prosthesis
Total dentures are used to restore a masticatory system when all the teeth in the jaw in question are missing. As a rule, they consist of special plastics, but can also have additional metal reinforcements.
Total prosthesis with metal-reinforced base (palatal plate)
Total prostheses are held in the upper jaw primarily by the base (palatal plate), which, depending on the construction, develops a suction effect or uses adhesive forces. In the lower jaw, with a much smaller base, additional forces are often exerted by the surrounding musculature.
Please note: dental prostheses are always custom-made, i.e. there are always many solutions that can only be worked out individually.
Stable-base prosthetics are a special design feature.
2019 Dr. Andreas Stein, Dentist, Oral Surgery Wiesbaden, Germany