Ceramic Inlays (Porcelain Inlays)
Introduction
Ceramic inlays have no metal core and are therefore translucent. They are bonded to the tooth using a special adhesive method, leaving no marginal gaps. A chemical bond is created between tooth and ceramic, restoring weakened teeth to their original strength. The high translucency yields an exceptional aesthetic quality.
What is an inlay?
Inlays are indirect fillings applied in back teeth (premolars, molars). After removal of the old, defect filling or caries, an impression is made of the cavity (that is the drilled out defect). A filling is then made in the laboratory from gold or ceramic, which fits the cavity with the utmost precision and restores the original form of the tooth. In the second session, the inlay is cemented into place. Large inlays which cover the cusps are referred to as onlays.
For many years, gold inlays have been the tried and tested solution and have a long lifespan. Today, aesthetic awareness has led to a decline in their use.
What are the advantages of ceramic inlays?
Ceramic inlays have no metal core and are therefore translucent. They are bonded to the tooth using a special adhesive method, leaving no marginal gaps. A chemical bond is created between tooth and ceramic, restoring weakened teeth to their original strength. The high translucency yields an exceptional aesthetic quality.
Ceramic is exceedingly biocompatible. For example, allergies such as to certain alloys are unknown.
Ceramic inlays are long-lasting. The following diagram shows the longevity comparison between composite fillings and ceramic inlays
Can all teeth be fitted with ceramic inlays?
In principle, all back teeth (molars and premolars) can be fitted with porcelain inlays. Front teeth (incisors and canines), on the other hand, are treated with composites. Only in cases where the defect (caries or filling) reaches deep under the gum, or where the remaining tooth substance is weak and brittle (for example root-canal-treated teeth), is a crown the better and lasting alternative.
What is the view on computer-milled porcelain inlays (for example CEREC®)?
Instead of taking an impression, the cavity is scanned by laser. The data is then transferred to a computer-controlled 3D milling machine, which mills the inlay from a block of ceramic. The inlay is fitted in the same session.
At our dental office, we prefer inlays made in the laboratory after an impression. These are far superior to the computer inlays in form (marginal fit), occlusal function (intercuspidation), and shade.
The only argument for Cerec® inlays is the saving made on laboratory costs, as well as the ability to fit a restoration in only one session (although a very long session).
The actual case
Fig. 1
Three defective amalgam fillings (premolar and two molars).
Fig. 2
The teeth are isolated from the rest of the oral cavity by a rubber dam. Following the painless anesthesia using the Peripress-method, the amalgam is removed using a water-cooled drill and suctioned away. This method eliminates any chance of contamination with heavy metals or quicksilver.
Fig. 3
As the premolar’s defect is not too deep, the restoration is made with tooth-shaded composite. Both molars are prepared for ceramic inlays.
Fig. 4
The impression is made with a small, single-sided tray, which does not cover the entire palate. Upper and lower teeth are precisely registered at the same time, cutting out the need for additional bite registration. There is no nausea or choking as with normal impression trays.
Fig. 5
The finished ceramic inlays before fitting.
Fig. 6
After adhesive cementation of the inlays. Aesthetic, functionality and stability of the treated teeth are fully restored.
Advantages and disadvantages of ceramic inlays
+ Long-term durability
+ Strengthening of the teeth
+ Fairly expensive
+ Ideal biocompatibility
- Time-consuming, two sessions required
- Defects reaching under the gums can be problematic