An inlay or onlay is a dental restoration of the tooth after a caries or an old amalgam filling has been removed. It is a high-quality and durable dental restoration. The inlay or onlay can be made of various materials and cemented or bonded precisely into the broken tooth.
When selecting materials, it is essential to pay attention to biocompatibility, durability and aesthetics.
Our dental office has its own dental laboratory and specializes in ceramic inlays. The best materials are selected according to biology and durability.
The entire manufacturing process is finely tuned so that the accuracy and fit of the inlays can be optimally achieved.
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What are inlays and onlays?
Every day, our teeth are exposed to strong chemical and physical stresses. For example, caries can cause a defect in the tooth, which should definitely be restored.
Inlays and onlays consist of one piece and have the task are made to replace this exact lost tooth part. Inlays and onlays do not differ in their function, but only in their shape and size.
An inlay is relatively small in size and restores the inner part of the occlusal surface. It is always used when the tooth defect is rather small.
An onlay expands over the entire occlusal surface of the tooth and is necessary when the tooth defect is large.
When are inlays and onlays used?
Every healthy tooth has an ideal anatomy. This ensures that food is chewed optimally, no food gets stuck between the teeth and the jaw joints are not subject to any overload.
In various situations it is necessary to repair teeth with inlays or onlays:
1. Caries
The acid of some strains of bacteria can etch holes in the tooth. This defect in the tooth should definitely be repaired in an anatomically correct way. Inlays and onlays are recommended as a treatment for larger caries.
2. Amalgam removal
Amalgam fillings have a detrimental effect on health and should definitely be removed under effective protective measures. After removal, the missing tooth substance can be replaced very well with inlays or onlays.
3. Broken tooth
Occasionally, part of a tooth may break off. Teeth that have already been drilled or that have caries can easily break when force is applied. The broken piece of the tooth can be restored with a high-quality inlay or onlay.
4. Reconstruction of occlusal surfaces
In patients with incorrect tooth contacts, the temporomandibular joints are often compressed and forced into a non-physiological position. This causes the temporomandibular joints and surrounding tissues to change and can affect the entire body. This condition can lead to typical symptoms of TMJ disorders, which can greatly affect the quality of life.
To treat this, the incorrect tooth contacts must be eliminated by a special splint (MAGO splint), which allows the temporomandibular joints to slowly regenerate into the correct position. Once the regeneration of the temporomandibular joints is complete, the TMD symptoms should disappear completely. To prevent the old bite from bringing the regenerated temporomandibular joints into the wrong position again, the correct position of the teeth must be restored. This is done by a complete reconstruction of the occlusal surfaces with inlays, onlays and veneers. This reconstruction can also be combined with orthodontics.
For simplicity, only the term inlay is used in the following part of the article, however onlays are also included.
What material are inlays made of?
There are various materials that can be used for the production of inlays. All of them have their specific advantages and disadvantages.
Ceramic Inlays
Ceramic inlays are also called ceramic fillings. They can be made from different types of ceramics.
The use of ceramic is highly recommended because of its biocompatibility, fit, longevity and aesthetics. It meets the all the requirements for high-quality aesthetic dentistry.
The accuracy and precision of the fit strongly depends on the type of ceramic and the manufacturing process.
During treatment and production, great care must be taken to maintain a minimum layer thickness, otherwise chipping may occur.
Provided that an experienced team of dentists and dental technicians carries out the dental restoration, an ideal result can be achieved with the use of ceramics.
Gold Inlays
Gold has proven to work as a dental material used for inlays over many decades. Gold inlays have a very accurate fit as well as longevity.
However, gold is less aesthetic and has unfavorable health properties. The lack of biocompatibility has been reported, among others, by the IMD Institute for Medical Diagnostics Berlin, detected in numerous samples and studies.
Gold and ceramic inlays
This type of inlay is made of a combination of gold and ceramic. Ceramic makes up the largest portion and the inner layer facing the tooth is made of gold.
Overall, gold/ceramic inlays show a very good fit and longevity. However, because of their poor biocompatibility, gold/ceramic inlays are not recommended.
Titanium inlays – Titanium inlays
Titanium in dentistry is actually known from dental implants. It is the most commonly used material in implantology.
Titanium inlays have a good fit and longevity. However, many patients dislike the unaesthetic, metallic-greyish color.
Just as with gold, titanium has several health concerns.
Composite Inlays
There are many different materials that can be used for composite inlays. Depending on the quality of the material and the method of production, the result can vary greatly.
If produced correctly in a dental laboratory with high-quality material, composite inlays can be an alternative to ceramic inlays.
However, composites do not come close to the biocompatibility and stability of ceramics.
Note for choosing the right material:
In general, metallic materials show high thermal conductivity. Thermal conductivity, as the name suggests, describes the ability to transmit temperature. Consequently, teeth that have a metallic restorations may experience pain with hot and cold food and beverages.
Ceramics and composites have low thermal conductivity, which eliminates this disadvantage.
When is an inlay reccomended – filling, inlay or crown?
As mentioned above, inlays are used to restore missing parts of teeth, for example because of caries. This gives the tooth back its original natural shape.
If the caries is small, the defect can be repaired with a classic filling made of composite. In many cases, this is possible without any complications.
If the tooth defect is extensive and anatomical reconstruction in the mouth is difficult, then ainlay is recommended. This way, the dental technician can optimally reconstruct the ideal shape of the tooth. With a filling on the other hand, there could be a risk of insufficient contact with the neighboring tooth and food could get stuck inbetween.
If the patient prefers a solution with the best tolerability and durability, an ceramic inlay should be chosen. Ceramic inlays are also ideal in terms of aesthetic dentistry.
If the natural crown of the tooth is too badly damaged, it should be replaced with a crown, preferably made of ceramic. In this case, a dental filling or inlay would not be suitable.
The correct choice for dental restorations made according to the individual situation, is of great importance so that the stability and anatomy of the teeth can be ideally restored. The dentist should always take into account the biocompatibility of the material.
How are inlays attatched to the tooth?
Inlays have the function of replacing the missing part of a tooth. In order for the missing piece to be fixed, it is cemented or glued into the tooth.
Attatching the inlay with cement
There are various types of cements used in dentistry. These adhere the inlay onto the tooth and ensure a firm and definitive bond.
Common cements include glass ionomer cement, zinc oxide phosphate cement (Harvard cement) or carboxylate cement. These have proven to be effective over many decades, and depending on the material of the inlay, can be used for cementing.
Cements have a good overall biocompatibility and low susceptibility to moisture while cementing dental restorations.
However, depending on the material, the stability is lower than adhesives made of composites.
Attachment with adhesives
Adhesives made of composites have a similar structure to the composites used for fillings. The adhesive is used in combination with a liquid bonding (a connector), which creates a strong bond between the tooth, adhesive and inlay.
This type of attatchment is very strong and stable.
Unfortunately, composite adhesives have many toxic and allergenic ingredients, so the biocompatibility decreases. In addition, composite adhesives are sensitive to moisture, which must be considered when attatching the inlay.
Treatment procedure in two appointments
This is the classic procedure for inlays.
First appointment:
- Removal of caries or amalgam filling
- Tooth-friendly adaptation of the existing tooth defect for the inlay
- Impression with hydrocolloid / silicone or digitally with an intraoral scanner
- Temporary filling to protect the tooth
The impression is sent to the dental technician. The inlays are produced in the dental laboratory. The production takes approx. 7 days at an external dental laboratory.
Second appointment:
- The temporary filling is carefully removed and the tooth defect is cleaned
- The inlay is attatched with a cement or composite adhesive.
- Excess cement or adhesive is thoroughly removed
- The tooth contacts are checked and adjusted if necessary.
Process of treatment in one appointment (chairside)
The two treatment appointments can be combined into one day.
The first part of the treatment is performed in the morning. After that, the patient has a break for a few hours. During this time, the inlays are produced in the dental laboratory.
After the break, the patient comes back for the second part of the treatment.
This way, the inlays can be produced and attatched in one day.
This chairside treatment can only be done if the practice has its own dental laboratory or with the help of CEREC.
In-house dental laboratory
With the help of an in-house dental laboratory, the dental technician can concentrate 100% on the patients of the dental practice. As a result, laboratory-produced, precise inlays can be produced and placed in a single day.
An advantage of dental laboratory-produced inlays is that they can be milled with the highest precision. A 5-axis grinder with super fine 0.3mm wide cutters can produce an optimal fit and precision.
As a result, inlays have an excellent fit and the cement gap can be reduced to a minimum.
CEREC
CEREC stands for CEramic REConstruction. This is a procedure which enables dental practices to produce ceramic inlays quickly and easily.
With CEREC, a treatment with inlays can be done in one day.
The dentist makes a digital impression with an intraoral scanner, sends the information to a small milling machine, which grinds the inlays from ceramic blocks.
This procedure is simple and gives a good result.
However, there are some disadvantages. The small grinding machine has only 4 axes and the finest drills are 0.5 to 0.6mm wide. As a result, there is a loss of precision and fit.
Cost of inlays
CEREC ceramic inlay: approx. 1000 CHF
Dental laboratory-made ceramic inlay: approx. 1200 – 1600 CHF
Gold inlay: approx. 2000 CHF, costs depend strongly on size and gold price
Gold/Ceramic inlays: approx. 1600 CHF
Titanium inlays: approx. 1200 CHF
FAQ on the subject of inlays
How long does an inlay last?
With a healthy oral bacterial flora, inlays can last 15 to 30 years. In our practice, we place emphasis on keeping the oral bacterial flora healthy and stable.
Does it hurt to get an inlay?
Many patients do not require an injection and do not find the treatment painful. However, local anesthesia may be necessary.
Do I need a local anesthetic?
It depends very much on one’s own pain tolerance. You may require a local anesthetic.
How long does it take for cement or adhesive to harden completely?
As a rule, the cements and adhesives require approx. 24 hours to harden completely. However, during this time you can eat normally.
How should inlays be cared for?
The duration of an inlay is very dependent on a healthy oral bacterial flora. This can be permanently optimized and stabilised in our practice.
Can inlays break?
Depending on the material, inlays can break. This is particularly the case with ceramic inlays that are too thin. However, with the correct care, it happens very rarely.
Which inlay materials meet the requirements of aesthetic dentistry?
Ceramics and composites can be ideally used in aesthetic dentistry. Especially the aesthetic appearance of ceramics is suited for this.
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