Crowns on the teeth. Which are better?
A dental crown is a fixed prosthesis that is used in cases of tooth decay of more than 50 percent in order to restore the functional load and aesthetics of the tooth. In other words, it is a prosthesis that mimics a real tooth.
Dental crowns – types and features
Crowns can be divided into groups:
Temporary and permanent
By manufacture: stamped, cast, pressed
by material of manufacture: metal, plastic, composite, ceramic, zirconium and combined
fixing: cemented, screwed, pin
on supporting elements: single, supporting in bridges or telescopic component
according to the manufacturing method: direct (done directly in the patient’s mouth) and indirect (made by a technician in the laboratory).
Steps for making crowns
Almost always the same, and consist of two: medical and laboratory.
The medical stage:
Sawing a tooth is usually removed from 1 to 3 mm of tooth tissue, depending on the crown.
If the tooth is dead or it is necessary to treat the canals (depulse) in it, then the tooth is often pinned (reinforced), which gives it the strength and reliability of the future design. The pins can be standard: titanium, fiberglass, steel, carbon or cast: steel, titanium, silver, gold and combined. Milled: zirconium or metal.
Impression – historically the most accurate impression was from plaster, due to the fact that it did not shrink. But he was not comfortable at work. And in the nineteenth and twentieth centuries, silicones and polyvinylsilaxanes appeared – this was a breakthrough in dentistry. But shrinkage appeared in them, which very badly affects the final result of the work.
After receiving the impression, the work falls on the table to the dental technician, in the laboratory, and the technician proceeds to the production of models: working and auxiliary. After the gypsum has hardened, the next step is the modeling of the future tooth from wax under a single crown or under a cap for applying ceramic, plastic or composite.
Then the work is transferred to the foundry laboratory, where the caster solders the sprues to the wax and casts the prosthesis from the metal.
Then the work returns to the dental technician, where he cuts the sprues, adjusts the prosthesis on a plaster model and passes it to the doctor for fitting.
After fitting the prosthesis, if there are no comments from the patient and the doctor, the work returns to the laboratory for grinding and polishing, if it is a metal prosthesis and for applying ceramic / plastic / composite, if it is a combined work and its transfer to the doctor.
The medical stage – fixing the finished crown on the tooth.
So, let’s try to understand each type of crowns and choose the best option.
One piece crown
It is modeled from wax, and then cast from metal, then polished to a mirror shine. And you can also apply damask spraying or make it of gold.
Pros: reasonable price of 20-40 euros, strength.
Cons: low aesthetic indicators.
Conclusion: an economy crown, which may well fulfill its function.
Note: it is most often used on the last upper chewing teeth (as the patients themselves say – “where they are not visible”). You cannot use these crowns if the antagonist crowns are ceramic or cermet – this leads to chips of ceramics.
Most often made of plastic for a short time. For a while, the dental technician makes a permanent crown.
Pros: an acceptable level of aesthetics and the cost of 20-30 euros.
Cons: fragility, porosity and the presence of residual monomer, which destroys the gums and, in some cases, causes allergies in patients. That is, technically, the powder (polymer) and the liquid (monomer) are mixed and polymerized to the final result. But, the residual monomer (solvent) still remains. The need for fitting the design in the patient’s mouth (due to the peculiarities of the manufacture of the crown) Most often, getting the perfect result when using this type of crowns is problematic. With prolonged use, due to the residual monomer, it can cause gum disease (gingivitis or periodontitis).
temporary tooth crown
But, there is an alternative to a temporary crown made of plastic.
At iStomatolog Center, temporary crowns are milled and / or printed on a printer from a special PMMA composite – polymethylmethacrylate, thermoplastic, synthetic material or PEEK-polyether etherketone, a biocompatible and wear-resistant material, durable as a human bone.
Pros: accuracy and manufacturing time due to digital technology, strength due to the composition of the material. The absence of residual monomer and the absence of allergic reactions, the inert material is resistant to oxidation, lightweight and, importantly, these materials are inert chemically and biologically, which allows them to be disposed of without any danger to the environment.
Cons: used as a temporary construction.
Conclusion: a temporary crown is indicated to replace a lost tooth for a short period.