Ceramics for dental restorations have evolved from fragile materials made from naturally-occurring minerals to high-strength synthetic ceramics of today. Manufacturing techniques have moved from purely manual processing to computer assisted design and manufacture (CAD/CAM). The development has been rapid during the last 20 years and is still ongoing regarding the balance of esthetics and strength, and cementation procedures.
Introduction
Nowadays, ceramics are applied in a wide range of industrial applications such as cutting tools, nuclear reactors, automotive, biomedical, etc. Therefore, ceramics have been the subject of considerable researches because their chemical stability and good mechanical properties compared to many other materials. Physical and mechanical tests, combined with fundamentals of engineering science, were made to structure designs and restorative materials. However, although these materials are esthetically attractive and resistant to wear, they are prone to brittle fracture at stress concentrations.
Dental ceramics are mainly consisting of glass ceramics enriched with lithium disilicate, leucite, polycrystals of zirconia and alumina, etc.
Therefore, several works have been made in the field of dentistry by using of computer-aided digitizing (CAD), computer-aided design (CAD), and computer-aided manufacturing (CAM). There are three types of ceramic used in dentistry:
- Ceramic crowns
- Ceramic veneers
- Ceramic dental bridges
What are ceramic braces?
Ceramic braces use clear or tooth-colored brackets rather than gray or metallic silver brackets and wires to correct deformities in your teeth, such as misalignment.
Here are some advantages of ceramic braces over metal ones.
- Ceramic braces are less visible than metal braces. They can match the color of your teeth. So, you do not feel self-conscious as you might feel with metal braces.
- Metal braces can interfere with the results of imaging tests. Ceramic braces offer none to very little interference compared to metal braces in imaging tests.
Disadvantages of ceramic braces
- Ceramic braces are costlier than metal braces.
- Ceramic braces are larger than metal braces. Hence, cleaning or brushing them may pose a difficulty.
- They may cause swollen gums that are sensitive to touch and temperature.
- Ceramic braces are more likely to break off than metal braces. Hence, they are less durable.
- The fragility also makes the teeth straightening process longer than the metal ones due to multiple visits to the dentist.
- Ceramic braces can stain that cannot be removed. You need a replacement for the braces if you want to get rid of the stain.
What are ceramic crowns?
Ceramic crowns are designed to sit over a filled-down tooth. They help restore the chewing function without the filling eroding off the tooth. An all-ceramic crown is usually made entirely from porcelain or another type of ceramic.
All-ceramic generally looks the closest to a natural tooth. Hence, this option is particularly good for people who are very concerned about the appearance of their teeth.
You may also opt for a ceramic crown if you have metal allergies.
Another advantage of having ceramic crowns is their extreme resistance to temperature changes. Hence, you are less likely to experience sensitivity to heat or cold with this type of crown.
Despite all the advantages of getting a ceramic crown for your tooth, it does carry a few disadvantages. It is likely to break with force as compared to a metal crown. It can also wear due to grinding by the adjacent teeth while chewing food.
What are ceramic veneers?
Dental veneers are used to cover the front surface of the teeth. They can be made from ceramic (porcelain) or composite resin. The benefit of using ceramic dental veneers is that they resist stains better than resin veneers. They also give the natural look to the teeth by mimicking the light-reflecting properties of natural teeth.
Ceramic/Porcelain veneers have a number of advantages;
- They are long lasting (on average 10 to 15 years) and have great strength qualities, being more resistant to chipping/fracture.
- They are resistant to staining, and will not change shade over time.
- They are highly accurately fitting to the underlying tooth, ensuring no gaps or ledges to trap food/plaque – and extremely easy to maintain.
- Ceramic/Porcelain offers superior aesthetics as it mimics natural tooth enamel in translucency and light transmission.
What are ceramic dental bridges?
Dentists use dental bridges to close the gaps in your teeth and improve your smile. A dental bridge is actually a false tooth (called a pontic) that is held in place in between two adjacent teeth. To give your teeth a natural look, ceramic dental bridges are usually preferred over other metal dental bridges.
Advantages
Its strength is a definite advantage but allied to this is the attractive translucent finish of the pontic and crowns which give it a realistic appearance. This type of bridge is practically indistinguishable from your normal teeth.
Another bonus is that there is no fear of seeing a grey line at the edge of the gums. This is a particular problem with the porcelain fused to metal bridge which tended to display itself, especially at the edge of the gums.
But the all ceramic bridge removes that worry. No metal is used in the construction of the bridge plus the bridge is fitted above the edge of the gums. This ensures that your teeth and gums remain healthy and with minimal risk of an infection. Plus they are a good choice of bridge for anyone with an allergy to metal.
How is a ceramic bridge fitted?
The dentist will examine your teeth and gums and ask you a series of questions before deciding whether you are suitable for a bridge. If you are suitable then the procedure is in two stages as follows:
Stage one
The dentist will prepare your teeth for the bridge. This preparation involves cleaning and reshaping the tooth so that it is in a good condition for the bridge. This may mean removing a sliver of the tooth so that it will be a perfect fit.
What is important is the condition of the teeth either side of the gap in your teeth. These will be acting as a support for the bridge so it is vital that they are healthy and free from decay. If they are not then they will require some work before you are fitted for a bridge.
Following this, the dentist will take an impression of your teeth with a mould. This is a container filled with dental putty which is used by a dental laboratory as a blueprint for the production of your bridge.
The idea is that this mould is used to produce a model of your teeth which ensures that you receive a bridge which fits exactly within your mouth.
Stage two
You will have been fitted with a temporary bridge whilst your new bridge is being fabricated. This will usually be for two to three weeks.
You will be notified once your new bridge is ready.
The dentist will fit the new bridge into your mouth and will check the fit, appearance and position. He or she will want to be certain that it is comfortable, fits well and that you are pleased with the result.
Once this has been agreed the bridge is then secured in place with dental cement.
The dentist will provide you with instructions on caring for your bridge as part of a daily hygiene routine.
Disadvantages
Whilst this is a good choice of bridge there are a few disadvantages which you need to take into account. These include:
- The ceramic can wear down the natural teeth on either side of the bridge.
- Heightened sensitivity of your teeth to different temperatures, e.g. hot drinks.
- Bacteria can become trapped around the bridge which if not removed, may lead to an infection.
- Ceramic bridges can be expensive
- They are prone to cracking or breaking
Another consideration is the risk of a bacterial infection caused by smoking. If you are a smoker then take note that this increases the number of bacteria in your mouth which then increases the risk of an infection.
Comparing Three Ceramic Materials for Digital Dentistry
Ceramic materials are utilized for several dental applications and are distinguished by their good mechanical properties, high electrical resistance, high thermal conductivity, and excellent biocompatibility. Thus, the oxides, particularly alumina, zirconia, and silica are the most commonly used ceramic materials in the area of dentistry. These materials are classified based on their chemical compositions or based on processing methods.
As digital dentistry and computer aided design/computer aided manufacturing (CAD/CAM) become more prevalent in dental practice, it is imperative for clinicians to understand the advantages and disadvantages of various restorative materials. With multiple options to choose from, material selection becomes a key factor in successful restorative outcomes.
- More translucent than zirconia, lithium disilicate’s translucency and optical properties support highly esthetic indications.
- Lithium disilicate crowns can be fabricated with either conventional (lost-wax hot-pressing technique) or CAD/CAM processes.
- Compared to traditional metal-ceramic restorations, zirconia is utilized in various situations due to its biocompatibility, hardness, fracture resistance and esthetics.
- One of the advantages of zirconia is that it inhibits crack propagation through a process known as phase transformation toughening.
- The newest digital restorative materials being developed contain various combinations of ceramics and resin composites.
- This new generation of polymer-based restoratives combines the advantages of ceramics (durability and color stability) with those of composite resins (elasticity and low abrasiveness to the opposing dentition).
