Dental filling, Inlay, Onlay, and overlay are types of dental treatments used to restore cavities without using the new total prosthesis. These treatments help to preserve more natural teeth as they fit in the remaining part of the tooth like a piece of the jigsaw puzzle. 

 While Inlay, Onlay, and Overlay, these small dentures are manufactured like a complete denture (using cad/cam, milling, and staining), the dental filling is treated by filling directly dental material (amalgam, composite resin) into the cavities. These dental treatments are used mainly for posterior teeth to improve chewing and prevent further decay

 1. Dental filling

 A dental filling is a procedure used to fill a hole in a tooth to prevent further tooth decay. A filling is usually a simple and early treatment for tooth decay. However, it may be broken and allow leftovers trapped between the tooth and the filling. Thus, a regular dental check-up is necessary. The materials that are usually used for this treatment recently are amalgam and composite resin.

• Amalgam: a mixture of metals, including silver, copper, tin, mercury, and zinc. Although exposure to mercury can be toxic, amalgam is safe and effective to use for most people  

• Composite resin: Composite resin is a white tooth-colored material, so it matches the color of the other teeth and looks more natural than amalgam.

Dental Filling

  2. Inlay

 When the tooth decay area is too bigger for a general dental filling, an inlay will be considered an alternative method. Inlays usually cover the central part of the tooth or the area between the cusps and are positioned within the hard tissues of the tooth. They do not cover the cusps. For this reason, they are shaped to fit perfectly on your teeth, so can prevent leftovers from entering underneath tooth decay areas, creating further decay.  The material used for inlays usually is porcelain like other dental crowns, so it will be stronger and more durable compares with other composite fillings.


  3. Onlay

 When a patient gets a decay of the middle and side of your tooth, an Onlay can be considered a treating method as it may cover one or more cusps of your tooth. Compared with inlay, Onlay covers more areas, they are positioned inside the deep tissues of the tooth as well as covers part of the biting surface of the tooth. This helps to protect the damaged tooth from a direct chewing load.


 4. Overlay

Overlays cover a much larger portion of the occlusal or biting surface. Though they are often compared to partial crowns, overlays are very different from crowns. The main difference is overlays keep more of the natural tooth structure intact.


  5. What is the difference between Inlays, Onlays, and Overlays?

aDental Filling

  • Size: large or small, depending on the position of the tooth decay
  • Function: Used to treat tooth decay in the early stages, preventing tooth decay from spreading
  • Production process: The dentist will fill the tooth directly at the dental office, not through the production lab
  • Duration and durability: Fast treatment time, not as durable as inlays, onlays, and overlays, but still the most effective treatment for small, non-serious caries
  • Low price

b. Inlay

  • Size: small size because it only covers the central point of the treated tooth and does not cover the cusps
  • Function: When the patient has severe caries, the cavity is large and spreads on the tooth surface
  • Production process: The dentist will take an impression of the teeth, then send it to the production lab. The manufacturing process is similar to a denture, including dental design, milling, contouring, and staining.
  • Treatment: Dentists will use dental glue to stick the inlay piece to the treatment area. The patient’s natural teeth are less affected by inlay teeth keeping up to 60-70% of natural teeth.
  • Time and durability: It usually takes 10-15 days for the patient to receive the inlay teeth. Part of the inlay production material is porcelain, so the inlay has high durability.
  • Cost: is the same as one complete tooth

c. Onlay

  • Size: the size is larger than the inlay tooth because it covers the central point of the treated tooth and covers 1 part of the cusps
  • Function: When the patient has severe caries spreading to the cusp, or the tooth has a slightly chipped tooth that needs covering
  • Treatment: Dentists will use dental glue to stick the piece of onlay tooth to the treatment area. With onlay teeth, patients retain 50-60% of their natural teeth.
  • The production process, durability, and cost: similar to inlay teeth

d. Overlay

  • Size: the size is almost the same as a complete denture, so dentists often consider the overlay and crown to be the same
  • Function: Used to replace severely damaged and chipped cases of natural teeth, and the roots are still in good working order.
  • Treatment: Dentists will use dental glue to stick the piece of onlay tooth to the treatment area. Patients will retain about 20-30% of their natural teeth with overlay teeth.
  • Process, time, durability, and cost: similar to inlay teeth

6. How to manufacture inlay, onlay, and overlay at a dental outsourcing lab

Inlay, Onlay, and Overlay teeth manufacturing process is similar to the manufacturing process of a complete denture; these teeth are also designed on cad/cam to ensure a snug fit, using ceramic materials such as Zirconia, Emax upon request and stained to resemble natural teeth. At Xdent dental outsourcing, we commit to creating durable inlays, Onlays, and overlays that give our customers confidence. 

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Author: Xdent team


Onlay at Xdent


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