Crowns are a type of dental prosthesis that restores the anatomical structure, chewing function, and aesthetics of severely decayed or completely lost teeth.
Expert opinion
If the tooth is 50% or more destroyed, a single crown is placed. In case of complete loss of a tooth unit, the patient is fitted with a bridge. Depending on the number of lost units, it consists of 3-5 crowns and is attached to the supporting, healthy teeth.
What are the different types of dental crowns
According to the composition, there are metal-free crowns (ceramic, zirconium, plastic) and metal crowns (solid or with a metal framework covered with layers of ceramics).
Metal-free crowns
Ceramic E-max – indicated for restoring the aesthetics of the frontal group. The shade and optical properties of the material are close to real enamel. It is difficult to distinguish e-max dentures from natural teeth.
Depending on the manufacturing method, E-max comes in 2 types:
- IPS E-max PRESS / IPS E Max Press Multi – ceramics obtained by pressing under high temperatures and pressure. The classic technology involves the production of a ceramic cap to which additional ceramic layers are applied in the future and then colored.
- E Max Press Multi is a modernized manufacturing method. It involves the creation of a monolithic frame that initially has the desired shade, shape and optical properties.
- IPS E-max CAD – the technology consists of creating a prosthetic structure by 3D milling from a three-dimensional image of the patient’s mouth. CAD/CAM ceramics are not as strong as pressed ceramics. The second disadvantage is the smaller selection of shades of future prostheses.
Pros:
- Service life of more than 15 years. Hypoallergenic. Excellent aesthetics.
Minuses:
- Not suitable for lateral dentures (6-7-8 molars).
- You can’t make a bridge longer than 3 crowns.
- Should not be placed in patients with bruxism.
- High price.
Zirconia crowns are a material that combines the aesthetics of ceramics and the strength of metal-ceramics. It is made of pressed zirconium blocks using CAD/CAM technology – milled on a machine in an automated way.
Three types of zirconia designs are common in modern dentistry:
- Combination. They are based on a frame made of opaque zirconium dioxide in a bright white shade. To improve aesthetics, the framework is covered with layers of porcelain. The disadvantage of these crowns is chipping of the ceramic layers (occurring in >10% of patients 5 years after the placement of such prostheses).
- Monolithic. Made of standard white zirconia disks that have almost no transparency. They are not coated with ceramic. Therefore, the resemblance to real teeth is achieved by mechanical coloration after the milling stage. Recommended for masticatory prosthetics.
- Multi-layer monolithic (Multi-layer). They are made entirely of zirconia, exactly mimic the structure of real enamel and are very strong. Aesthetically almost as good as E-max ceramics. They have an immediate color gradient and transparency like real teeth, as they are made of pre-colored blocks with four layers:
- one in the neck area,
- two transitional layers,
- one translucent layer in the cutting edge area.
Pros:
- High Aesthetics.
- Withstand high chewing loads.
- Biocompatible (do not cause allergies).
- Serves up to 20 years.
Minuses:
- Not all types of zirconia dentures are suitable for placement in the smile area (e.g., monolithic dentures).
- Subject to chipping (e.g. combined).
- High cost (Multi-layer).
Plastic – in dental prosthetics they are used as a temporary solution (provisor crowns) to restore aesthetics and chewing function, as well as to protect the prepared units from bacterial flora. They are used in cases of:
- If a patient’s teeth have been ground down to fit a permanent denture, it takes up to two weeks for a dental technician to create it.
- For implant-supported prosthetics with immediate loading. Plastic prostheses are fitted immediately after implantation of the titanium stem.
There are 2 types of plastic crowns:
Acrylic is a budget option. They are made of monomeric, composite or non-monomeric plastic. Monomer caps are the most common due to their low cost relative to other materials.
However, the low price tag is due to the rapid wear of the prosthetic structure and the release of monomer from it. This provokes allergic reactions in the patient, inflammation of soft tissues in the area of prosthetics.
Composite and monomer-free dentures are safer. There is no toxic monomer in them and the risk of allergies is low.
Polymethylmethacrylate (PMMA, Russian: PMMA). PMMA is created by milling on an automated machine. The doctor takes impressions of the prepared units, creates a plaster cast, digitizes it on a computer, and then sends it to the machine.
PMMA crowns are highly accurate, fit securely to the tooth neck, and are highly biocompatible. Aesthetics depends on the PMMA blocks from which the prosthetic construction is made.
They are available in single-layer and multi-layer (Multi-PMMA). The latter means that the block from which the prosthetic structure is made already has the desired shade and transparency. The finished prosthetic structure will be similar to the patient’s real teeth.
Minuses:
- Low Strength.
- Temporary solution (lifetime 2-3 years).
- There is a possibility of developing inflammatory processes in the area of the prosthesis.
Metal-containing crowns
Metal (solid-cast) – increasingly rare in modern dentistry. They consist of cobalt/chromium or nickel/chromium alloys. The finished structures look like polished metal with a color far from the shade of real enamel. They are used to replace the chewing areas.
Some patients prefer gold-plated metal crowns, which can irritate the oral mucosa.
Pros:
- High strength, wear resistance.
- CAD/CAM manufacturing
- Minor preparation of dental units.
- The service life is at least 10 years.
- Low price.
Minuses:
- Lack of aesthetics.
- Risk of allergy, irritation of adjacent soft tissues.
Metal-ceramic crowns are crowns with a framework of metal up to 0.5 mm thick, covered with layers of ceramic. There are 3 types of metal-ceramic crowns:
- Classic. This is based on a cobalt/chromium alloy framework that is covered with ceramic everywhere except the ledge. The area of the alloy in contact with gum tissue may cause lividity or contribute to gingival recession.
- Improved. The same framework, only the ledge is already covered with ceramic mass. The metal base is no longer in contact with the gum. This provides better aesthetics: it prevents the root of the tooth from being exposed or the gum from turning blue.
- On a frame made of precious metals. The framework is made of gold, silver or platinum and is also covered with ceramic. A gold framework can give the crown the usual yellowish color, while a silver framework can darken the gum. An allergic reaction is excluded.
- CAD/CAM. The computer creates a three-dimensional model of the metal-ceramic prosthesis based on the patient’s impressions. The information is transferred to a milling machine, which produces the prosthetic structure quickly and accurately.
Pros:
- High durability.
- Not a bad aesthetic.
- Tight fixation.
- Lifespan ~15 years.
Minuses:
- Severe debridement of dental tissue.
- Tooth depulping.
- Risk of lividity around the denture, allergies or gingival recession.
- High cost (if the frame is made of expensive metal or CAD/CAM).
Classification of crowns
| By purpose | By manufacturing technology | By material | By design features |
| Restorative | Cast | Metal | Complete (actual complete, telescopic, incisional with post) |
| Supports | Stamped | Metal-free | Partial (equatorial, three-quarter, half-crowns) |
| Fixing | Ceramic | Combined | |
| Preventive | Polymeric | ||
| splinting | |||
| Provisors | |||
| Orthodontic |
Which crowns are best to put in
The choice depends on whether the restoration is needed at the front or the side of the tooth row.
In the frontal division.
Despite the impressive variety of crowns, only a few of them are suitable for the frontal dentition. Restoration in the smile area requires a high level of aesthetics from the prosthetic structure. The main factors are:
- Dentures should not stand out in color, shape and transparency against the whole dentition;
- It is necessary to eliminate the risk of lividity of the gingiva after prosthetics.
So, what kind of dental crowns are worth placing in the anterior region:
E-max Ceramics. The best material for restoring one or more units with single crowns. If an Imax bridge is needed, it will be no longer than 3 crowns.
Expert opinion
Glass-ceramic is identical to natural enamel in terms of transparency, light transmission and shade variation. Only an in-office dentist can distinguish Imax ceramics from natural teeth.
Zirconium. The material itself is high-strength and does not need an additional framework, which greatly enhances the aesthetics of the prosthetic structure.
However, some zirconia dentures are made of inexpensive, opaque blocks of zirconia and coated with ceramic. This means that the dentures end up looking unnatural. Moreover, the ceramic surface gradually develops chips.
Get Multi-layer monolithic zirconia crowns. They are not covered with ceramics and are close to natural enamel in shade and transparency.
What features of zirconia crowns are worth considering?
Since zirconia has a limited range of shades, patients with complex enamel color should have these crowns placed in the entire anterior region (6-10 teeth). Zirconia is suitable for the fabrication of bridges for 4-5 tooth units.
If 1-2 units need to be restored, a frame is made from a “Multi-Layer” monolith, which is covered with layers of porcelain to give the desired shade.
Metal-ceramic. In order for them to be aesthetically as good as ceramic dentures, we recommend placing dentures with a high-quality ceramic coating and shoulder mass. This will help to avoid aesthetic defects of the smile (lividity, dark lines along the contour, translucency of the framework).
You can save on budget by choosing to insulate only the front of the denture structure with ceramics rather than the entire perimeter of the ledge. Metal-ceramics can be used to restore one or several dental units. In the latter case, a 4-5 tooth bridge can be fabricated.
In the masticatory sections
Zirconium dioxide. The best substitute if a bridge is to be placed in the lateral region supported by molars/premolars or implants. Zirconia teeth (like E-max ceramics) are available as monolithic or double-layered (zirconia framework is covered with ceramic).
The first option is more reliable, but less aesthetically pleasing. Zirconium with ceramic looks more natural, but there is a risk of chipping of the porcelain coating. Given that aesthetics are not as important as reliability in the lateral areas, we recommend monolithic dentures.
E-max ceramics. Can be used if the aesthetics of the entire dentition is important and a single restoration is required. The Imax bridge does not have enough strength to cover 6-7-8 molars.
If a crown is to be placed in the chewing area, we recommend choosing a denture made of “Press Multi” – a monolithic, aesthetic material.
Metal-ceramics. A reliable, low-cost alternative to glass-ceramic and zirconia. Has such disadvantages as low aesthetics, risk of gingival recession and significant retouching of dental tissues – up to 2.5 mm (retouching with metal-free ceramics – no more than 1.5 mm). But when talking or smiling, the chewing sections are almost never noticeable. And on a limited budget, it is not a bad solution for restoring missing/damaged teeth.
One-piece metal prosthesis. Prosthetics of distant units do not require high esthetics. A cheap and durable replacement for lost painters. Consists of a hard alloy, has a silver color (gold plating can be applied). Advantages – long service life, less enamel grinding than in metal-ceramic prosthetics.
Combination bridges. If a bridge is needed for a masticatory group extending 3 or more teeth, a prosthesis can be placed in which, for example:
- The 2 crowns closer to the smile area will be metal-ceramic;
- the others (the far ones) are solid metal.
The advantage of such a bridge:
- Low cost.
- Minor turning of the supporting unit under the all-cast crown.
You can read more about what to choose in our article: best crowns for chewing teeth.
Comparison of crowns made of different materials
| Criterion | E-max ceramics | Zirconium dioxide | Metalloceramics |
| Aesthetics | It’s a great one | High | Medium |
| Strength | High | Excellent (monolithic) | It’s a great one |
| Biocompatibility | Complete | Complete | There’s a risk of allergies |
| Preparation | Minimal (1-1.5 mm) | Minimal (1-1.5 mm) | Significant (2-2.5 mm) |
| Depulpation | Yes + root canal filling | No | No |
| Place of installation | Frontal, masticatory groups (single restoration or bridge up to 3 crowns) | Frontal group (Multi-layer), Chewing group (monolithic) | Frontal group (prosthesis with shoulder mass or noble metal framework). Chewing group |
| Service life | 15-20 years | Up to 20 years | Up to 15 years old |
Contraindications to prosthetic crowns
Limitations for prosthetics are absolute and relative.
| Relative (temporary) | Absolute |
| Pregnancy, lactation period | Blood diseases |
| Chronic diseases in the stage of exacerbation | Cancers |
| Rehabilitation period after radiation therapy or severe treatment | Diabetes mellitus in decompensated stage |
| Periodontal disease at the stage of tooth mobility | Patient intolerance to prosthetic material, local and general anesthetics |
| New growths on the root of the tooth (granuloma, cyst) |
Questions and answers
Which is better metal-ceramic or zirconia?
Although zirconia is 1.5-2 times more expensive than metal-ceramics, most patients still choose it, and here’s why:
1. the hypersensitivity of the prosthetic area is eliminated.
Metal-ceramics reacts to a sudden change in temperature in the oral cavity and transmits it through the dentin to the nerve. Zirconia does not have this disadvantage, any pain is excluded.
2. Prepared teeth are less affected.
Monolithic zirconia crowns have thinner walls. Therefore, a thin layer of enamel is worn away. More healthy tissue is preserved, which means the tooth will last longer as a reliable support.
3. The pulp is preserved.
The nerve bundle is preserved due to minimal enamel retraction. Before metal-ceramic prosthetics, the nerve is removed because the residual limb is heavily ground.
4. More suitable for implant-supported prosthetics.
The gum tissue adapts seamlessly to the zirconia abutment and crown. The titanium implant does not show through the artificial tooth. The gingival margin grows in neatly, there is no blueing or gum irritation.
How to care for crowns?
Follow these simple guidelines and your dentures will last a long time:
- Take care of your oral hygiene. Brush your teeth thoroughly in the morning and evening.
- Clean with sweeping motions from the gum to the cutting edge.
- Choose a brush with medium to soft bristles.
- Floss to clean between the teeth at least once a day.
- If possible, use an irrigator to remove sub-gingival deposits.
- Rinse your mouth with water every time after eating.
- Avoid foods that are hard or too sticky.
- Don’t eat hot and cold at the same time (especially if you are standing metal-ceramic).
- Visit your dentist twice a year for a professional oral hygiene.
What are some alternatives to crowns?
A decayed tooth can be filled, a lost tooth can be replaced with an implant.
Filling is possible if the unit is not more than half destroyed. In this case, a post is fixed in the root canal to ensure the reliability of the filling. A tooth that has been destroyed by half or more cannot be filled, as there is a high risk of fracture.
If a tooth unit is missing, a titanium implant with a crown can be fixed. It has more advantages compared to other methods of restoring the integrity of the tooth row:
- can last a lifetime or at least several decades;
- does not require turning adjacent units;
- stops/slows bone atrophy (bone tissue continues to lose under the bridge structure).
If you check out this dentist in San Antonio TX, they will also recommend inlays or onlays. These are indirect fillings made from porcelain, gold, or composite resin that fit into or onto a tooth.
