What are dental inlays and onlays?

dental inlays and onlays

Dental inlays and onlays are customized ceramic fillings (custom dental restorations) used to restore significantly broken molars and premolars that can’t be saved with a filling nor require full coverage crowns. They are an intermediary between fillings and dental crowns.

What is the difference between dental inlays and onlays?

Dental inlays are custom dental restorations that restore wider and larger defects involving chewing and proximal surfaces. 

When cusps (elevations on the molars) of the teeth are also destroyed, an onlay is given. A dental onlay is an extended version of an inlay and includes cuspal coverage of the teeth. 

What is the difference between an inlay and a filling?

An inlay is a customized lab-made ceramic restoration that fits into the prepared tooth like a puzzle piece and is intended to rebuild a large tooth area. A filling, on the other hand, fills a small to moderate-sized cavity in the tooth and isn’t fabricated in the lab. The paste consistency of the filling conforms to the shape of the prepared cavity and hardens upon exposure to LED light or chemical reaction. 

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When Do You Need an Inlay?

More significant molar or premolar destruction with a loss of two or more walls often requires an inlay or onlay. An inlay and onlay is often indicated in high tress bearing area where composite id likely to fail within a few years. Extensive tooth defects resulting from tooth decay require a stronger material to reinforce the tooth.

Amalgam fillings can do this but aren’t preferred by patients due to their silver appearance, corrosion, and mercury toxicity.

Also, an inlay or an onlay may be given in a root canal-treated tooth with relatively less surface loss than required for a crown.

Moreover, a moderately large cavity where it’s challenging to maintain a dry field during filling. Moisture control is a prerequisite for a successful composite filling.

Read more: 10 Signs of healthy gums

How are inlays and onlays formed?

An inlay fabrication is a multi-step process and involves the removal of tooth decay with a dental drill. The walls are smoothened to obtain the impression of the cavity. An impression is taken and sent to the laboratory for fabrication. In the meantime, a temporary filling is placed in the tooth, and the patient is sent home. The lab delivers the filling after a week, cemented to the tooth with an adhesive. 

Some dental offices have a special chairside equipment called CAD CAM. CAD CAM machine takes a 3D impression of the prepared tooth, and the filling is prepared in the same visit and bonded to the tooth. 

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What materials are used to make inlays and onlays?

Gold, composite resin, or ceramics, such as porcelain or zirconium, are used to fabricate inlays. The chosen material is based on the aesthetic, strength, durability required, and affordability of the patient. For instance, most young patients choose ceramic inlays because of their tooth-matching properties and durability.

Factors influencing the longevity of inlays and onlays

The factors influencing the longevity of an inlay include:

  • The strength of the remaining prepared tooth. 
  • Patients with night grinding and clenching habits exert tremendous forces on the teeth, and ceramic isn’t an ideal material for them. Ceramic is harder than dental enamel and causes exaggerated enamel wear under excessive clenching and grinding pressures. Gold inlays are the preferred option in these cases. Also, leucite and lithium disilicate reinforced glass-ceramics have hardness close to the enamel can be used. 
  • Oral hygiene of the patient. 

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Patients suitable for Inlays and Onlays

The ceramic or composite inlays are appropriate for you if you have:

Patients Not Suitable for Inlays and Onlays 

Inlays are not recommended in the following patients:

  • Root decay
  • Periodontal disease and poor oral hygiene.
  • Enamel erosion (loss of enamel)
  • Excessive saliva production where it’s challenging to maintain a dry field during the procedure.

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What does a dental inlay look like?

A dental inlay resembles the shape of the prepared cavity. Ceramic inlays are 2-3 mm white fillings with a box-like configuration. 

What are the Benefits Of Inlays and onlays?

The advantages of dental inlays are as follows: 

  • Safe for the patient
  • The smooth and polished surface repels dental plaque deposition on their surfaces. 
  • Ceramics and gold inlays have remarkable mechanical resistance to wear.   
  • Slight chance of tooth sensitivity and secondary tooth decay due to snugly fit and bonding to the enamel.
  • Xerox copy of the tooth preparation.
  • Doesn’t discolour 
  • Seals the tooth and prevent the need for future root canal treatment (a problem associated with composite and amalgam fillings).

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What are the risks of having an inlays?

The following are the risks and disadvantages of inlays and onlays  

  • The dental inlays are costly as compared to composite or amalgam fillings.
  • Ceramic inlays and onlays cause wear of the opposing teeth. It can be very damaging in patients with bruxism habits. 
  • If the cavity is small, the ceramic may fracture. 

What is the life expectancy of inlays and onlays?

Dental inlays and onlays are strong and durable fillings and can last for 15-20 years if oral hygiene is maintained. However, failure may occur due to fracture of the restoration and loss of adhesive.

What is the cost of inlay?

Inlays and onlays are a bit expensive and require technical expertise and machinery to cast ceramic into the precise shape of an inlay and onlay. Roughly, they cost between $500-$1200. However, the cost varies with the type of material you choose.

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Does getting an inlay hurt? 

No, inlays don’t normally hurt. However, deep cavities close to pulp may hurt may cause sensitivity in the teeth and usually goes away in 7-14 days. 

How long after an inlay can I eat?

Refrain from eating until the numbness goes away. You can eat a soft diet for the first 24 hours. Its would be best if you eat from the side that is not operated. You can resume your normal diet from the next if there is no sensitivity. 

How long are teeth sensitive after inlay? 

The sensitivity in teeth occurs after a deep cavity preparation and may take 7-14 days to resolve. Instrumentation may irritate the dentin leading to sensitivity in the teeth. 


The dental inlays are customized fillings used for severely damaged and decayed premolars or molars. They are made in the lab from the impression of a prepared tooth and bonded to the tooth with an adhesive. Composite resins, ceramics, or gold are used to make them. 

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