INLAYS & ONLAYS
What is Inlays and Onlays:
Inlays and Onlays are indirect dental restoration that have been designed to restore large cavities caused by carries,or trauma. Additionally,root canal-treated teeth with sufficient remaining tooth structure could also be selected for these restoration.As for these large cavities,especially when there is cuspal coverage involved,it may be less predictable to be restored with normal direct fillings ( amalgam or resin ). As a result, the obvious advantages of Inlays/Onlays over those direct fillings is their strength.Moreover,when compared to crown preparations,Inlays/Onlays preparation are much more conservative because of tooth structure preservation.However,like other indirect restoration,Inlay/Onlays require at least “two clinical visit” to finish the procedure.
Step-by-step for Inlay / Onlays:
- Old restoration and remaining decay removed. Final tooth preparation.
- Impression and inlays/onlays fabrication in the laboratory.
- Inlays/Onlays delivery on the second visit.
Materials for Inlay / Onlay:
High gold alloys(type II or type III) are the most common alloys for inlay/onlay fabrication due to many good qualities. Bio-compatibility and good margin adaptation are among them. When compared to resin or ceramic, metal restorations are much stronger (not likely to break). Moreover, gold alloys are less abrasive than ceramic materials when used against dental enamel.
2.Tooth-colored materials; Composite resin and ceramics:
This type of materials is popular for their esthetics. A variety of shades can be selected to mimic tooth structures.
2.1 Composite Inlays/onlays:
This is basically an indirect technique for composite resin restorations. The inlays/onlays are made in the laboratory instead of directly on the tooth, as a result, contacts and contours can be more properly fabricated. Furthermore, sensitivity from polymerization shrinkage caused by direct resin filling is eliminated due to no light curing of composite resin on the tooth. However, since composite resin has limitations and tends to break more easily than ceramic materials, it is still much less popular compared with ceramic materials when it comes to ‘tooth-colored inlays/onlays’.
2.2 Ceramic Inlays/onlays:
Even though they are made of ‘ceramic materials’ which also known for the ability to break, many reinforcement techniques have been developed to enhance the strength of these materials and eventually become optimal for normal functions in posterior teeth. This is the major advantage of ceramics over composite resin. However, patients with para-functions such as night-grinding or clenching may not be suitable for these materials, metal alloys will have to be selected for better longevity of the restorations.
Normally, it will take around 2 visits (3-5 days) to complete the treatment.