What is the difference between the dental procedures of Fillings, Inlays and Onlays? - Station Street Dental

What is the difference between the dental procedures of Fillings, Inlays and Onlays?

What is the difference between the dental procedures of Fillings, Inlays and Onlays?


All three dental procedures – fillings, inlays and onlays are used to restore damaged teeth and treat cavities. Fillings are typically used to repair minor cavities and are made from either composite resin or amalgam. Inlays and onlays are used to repair more severe tooth damage, such as large cavities or cracks, and are usually made from porcelain or gold.

Dental Fillings

Fillings are the most common type of dental restoration and involve the removal of decayed tooth material and the placement of a filling material, such as composite resin or amalgam, to restore the tooth to its original shape and function.

If you have a cavity or have any other damage to your teeth, it’s best to visit your Dentist to see if a dental filling is necessary. Usually, a dental filling is used to repair damage to your teeth caused by cavities, fractures, or wear. Your Dentist will clean the affected area and then fill the cavity with a suitable material such as composite, glass ionomer, or dental amalgam. The material will then be shaped and polished to match the rest of your teeth. In some cases, a crown may be recommended to protect the tooth from further damage.

Depending on your case the dentist may give you a choice between a direct or indirect filling option. The direct filling option, which is the most common, involves the dentist using composite material to fill the affected area. The indirect filling option involves the dentist using a ceramic or porcelain material to restore the tooth. Your dentist will be able to discuss the different options with you and advise which one is best for your particular case.

Dental Inlays and Onlays

Inlays and onlays are more extensive dental restorations that are used when a large portion of a tooth needs to be replaced. They are dental restorations that fit snugly into the cavity of a tooth for a more precise, durable and aesthetic fit than a filling. Inlays are usually used when replacing damaged cusp tips, while onlays are generally used when replacing large portions of the chewing surface of a tooth.

The main difference between dental inlays and onlays is that an inlay is used to fill a cavity within the chewing surface of a tooth, while an onlay covers the entire chewing surface of the tooth. An onlay covers one or more cusps, or points, of the tooth, while an inlay does not. Additionally, inlays are used to restore small to moderate size cavities, while onlays are used for larger tooth cavities.

Dental Inlays in Detail

Dental inlays are typically recommended by dentists when a patient has a tooth with a cavity that is too large for a filling, but not large enough for a crown. However, dental inlays may not be recommended in cases where there is not enough healthy tooth structure left to hold the inlay in place, or if there is a large cavity. In some cases, a dental crown may be the more appropriate treatment.

Dental inlays are also used to reinforce a tooth that is weakened or cracked due to wear and tear or decay. Dental inlays can be used to restore the shape and strength of a tooth and help prevent further damage.

Dental Onlays in Detail

Dental onlays are typically recommended by dentists when a tooth has become significantly damaged or decayed, but not to the point of needing to be fully replaced. Onlays may also be used to reinforce a weakened tooth or to fill in the space between teeth. The procedure typically involves the dentist removing the damaged portion of the tooth, taking a mold of the area, and then having a custom-made porcelain onlay created by a lab. The dentist then permanently attaches the onlay to the tooth, which adds strength and stability to the tooth as well as improves its appearance. Onlays typically last for many years/decades (even up to 30 years with proper care), and can help to prevent further damage to the affected tooth in the future.

10 Point cheat sheet highlighting technical differences between Dental Fillings, Inlays and Onlays:

  1. Fillings are fabricated directly in the mouth, while inlays and onlays are fabricated in a lab and then cemented into the mouth.
  2. Fillings are smaller and more superficial, while inlays and onlays are larger and require more tooth structure to be removed.
  3. Fillings are typically made of composite resin or amalgam, while inlays and onlays are usually made of porcelain or gold.
  4. Fillings are used to repair small cavities, while inlays and onlays are used to repair moderate to large cavities.
  5. Fillings are typically used to restore single surface of teeth, while inlays and onlays can restore multiple surfaces of teeth.
  6. Fillings are more prone to staining than inlays and onlays if composite is used.
  7. Inlays and onlays require more time to place than fillings.
  8. Inlays and onlays require more precision to place than fillings.
  9. Fillings are less expensive than inlays and onlays.
  10. Inlays and onlays can last up to 30 years with proper care, while fillings may need to be replaced every 5-7 years.


The differences between fillings, inlays, and onlays are mainly related to the size and scope of their treatments. Fillings are the most common and least invasive of the three procedures, and are used to repair minor cavities and cracks. Inlays, and more so onlays, are used for more extensive repairs and require more time, effort, and materials to complete.

All three procedures offer a reliable and durable solution for dental repair, and should be discussed with a dentist to determine which one is most suitable for a particular situation.

At our clinic Station Street Dental in Officer Vic (and neighbouring to Pakenham, Beaconsfield, & Berwick), we are dedicated to helping you find the best solution to your cosmetic dental needs. We understand the importance of making sure that you feel comfortable and confident in your smile, and strive to find the most attractive and comfortable solution for you. Our team of experienced cosmetic dentists are specializing in a range of dental treatments, from veneers and implants to teeth whitening, and can customize a plan that is tailored to your individual needs. We look forward to helping you achieve the smile of your dreams.


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