Everyone heard about dental crowns, but most of us don’t truly understand what the manufacture of a crown entails, how painful it is, how durable they are and most importantly, does one really need them?
The use of dental crowns are justifiable in many cases, but not always necessary. The dental crown is a protecting shell, glued to the surface of the tooth, which should be manufactured in the following cases:
Root-canal filled teeth dry up, and the inside of the teeth is removed by the dentist during the process, making them fragile. Also these teeth usually get a huge filling, making them even more brittle. If these teeth do not get covered by a crown, they might become brown and even brake off. To protect these teeth from fracure and discolouration, it is advised to cover them with crowns. If the tooth is already broken (this is when patients most often visit the dentist), there is still hope to save it, as it can be reconstructed with a post core, after which a crown must be cemented on it.
An another indication of crowns are the teeth with extra large fillings, which are not only inclined to break but also visibly ugly on the front teeth (if not right after filling, but after a few months, they might become discoloured). If there is no danger of fracture and the filling does not extend to the palatal side of the tooth, the aesthetical problems can be solved with a porcelain veneer. This can give a perfect colour and shape to the front teeth.
Crowns can also be useful for „fast orthodontics” – not only the colour and shape of the teeth, but also their angulations can be corrected with crowns.
Most often however, crowns are used as part of a bridge, when resolving gaps between teeth. An alternative to this is implantation, when a titanium screw is inserted in the bone, covered with a crown, thus adjacent teeth do not need to be grinded (see our article avout implants).
Dental crowns can be made out of different materials, based on the needs of the patient and the requirements of the situation: the old metal-acrilate crowns are not really in use anymore, as the acrilate masking of the metal often fell off, it’s colour changed with time and it irritated the gum, causing inflammation. Instead of this, these days we use porcelain-fused-to-metal crowns (PFM) – this has a chromium-cobalt metal alloy base, covered by porcelain from all visible sides. These are best for the rear molar teeth, as they are durable and relatively aesthetic. An alternative is the zirconium crown, which is entirely tooth-coloured, without an underlying metal base. These are milled by a computer, and are used in case of metal allergy, or when the patients would not like to have metal in their mouths.
The highest aesthetic results are obtained by the e.max pressed ceramic crown, which is used on front teeth, and can perfectly mimic the natural colour of teeth. It is made entirely of porcelain, the transparency of which can be controlled by the technician during the manufacturing process, adjusting it based on the adjacent teeth. Obviously the material of the crown is chosen by the patient and the doctor, depending on the needs and possibilities.
The manufacturing process of the crowns is simple: in one sitting, under anaesthesia, with use of a magnification loupe, the dentist removes 1-2mm of the tooth’s enamel, preparing a shoulder at the base of the tooth – this will be where the crown ends (this is important, because if the doctor doesn’t do this, the crown will end somewhere in the tissues, with it’s edges not in a plane with the tooth’s surface, causing plaque retention and continuous inflammation of the gum). After this, the dentist will take an impression of the prepared teeth for the technician, who can thus start his/her art. The dental technician will put the porcelain layer by layer on the model, forming the shape and colour of the new crowns. While the work continues, the patient receives a temporary crown (right at the first visit), with which he/she can eat, smile and talk. As soon as the technician is done, the dentist will cement the final crowns on the prepared teeth, which will be usable and cleanable just like the normal teeth. The durability of correctly manufactured and well maintained crowns is 10-15-20 years, and usually it is not the crowns that fail eventually, but the underlying teeth.
Many patients seek out our dental clinic to receive crowns. Often this is not necessary, it can be solved in alternative, less invasive ways, like orthodontics, use of porcelain veneers or simply with fillings. It is always up to the patient and doctor to discuss and decide together, wether crowns are needed or not in every situation.