Dental inlays and onlays are durable partial coverage restorations used to restore significantly broken molars and premolars that can’t be saved with a filling. They are considered an intermediary between fillings and full-coverage dental crowns.
What is the difference between dental inlays and onlays?
Dental inlays are custom high-strength dental restorations/fillings that restore wider and larger defects on the teeth. For instance, a tooth which has lost two or more walls as a result of tooth decay.
A onlay is given on a tooth that loses one or more cusps (elevations on the molars). A dental onlay provides larger coverage including cusps than an inlay.
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 is placed directly on the tooth. The paste-like consistency of the fillings takes the shape of the prepared cavity and sets (hardens) upon exposure to LED light or a chemical reaction.
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When Do You Need an Inlay?
A molar or premolar which has lost two or more walls may require an inlay or onlay. The dental inlays and onlays are indicated in high stress-bearing areas where composite fillings are likely to fail within a few years. Extensive molar or premolar destruction from tooth decay require in an inlay or onlay to sustain high chewing stresses.
The high strength of amalgam or silver fillings allow them to used in these circumstances, but are denied due to their silver appearance, corrosion, and mercury toxicity.
Also, an inlay or onlay may also be given in a root canal-treated tooth to avoid excessive tooth cutting (for a crown) and restore the strength of tooth.
Moreover, an onlay may be recommended in moderately large cavities where it’s challenging to maintain a dry field during filling. Moisture control is a prerequisite for a successful composite filling.
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How are dental inlays and onlays formed?
An inlay is a multi-step process that involves removal of tooth decay with a dental drill. The walls are drilled parrallel to each other – a box-like configration. An impression is taken and sent to the laboratory for an inlay or onlay fabrication.
After the impression, a temporary filling is placed in the tooth, until the onlay or inlay is ready to be placed. The lab usually delivers it in 7-10 days. The restoration is checked for accurancy by placing it in the cleaned prepared cavity. The filling is finally cemented to the tooth with an adhesive.
Some dental offices have a special chairside equipment called CAD CAM. CAD CAM machine takes a 3D virtual impression of the prepared tooth, customizes the restoration and is placed in the same appointment .
What materials are used to make inlays and onlays?
Gold, composite resin, or ceramics, such as porcelain or zirconium, are used to fabricate inlays and onlays. The selection of the material banks on the aesthetic demands, tooth involved and affordability of the patient. For instance, young patients choose ceramic inlays because of their better tooth-matching properties and durability.
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Factors influencing the longevity of inlays and onlays
The factors influencing the longevity of an inlay and onlays include:
- The amount of tooth material left after the preparation.
- Ceramic isn’t an ideal material for people with grinding and clenching habits. It is tougher than tooth enamel and frequent grinding and clenching exert enormous forces on the teeth which can cause attrition (loss of tooth substance from the chewing surface) of the teeth in the opposing arch. Gold inlays are the preferred option in these cases. Also, leucite and lithium disilicate reinforced glass-ceramics have hardness close to the enamel and can be used instead.
- Oral hygiene of the patient.
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Patients suitable for Inlays and Onlays
The ceramic or composite inlays are appropriate for those who have:
- High aesthetic expectations
- Good oral hygiene
- Allergy to amalgam
- Significant tooth destruction
Patients Not Suitable for Inlays and Onlays
Inlays are not recommended in people with:
- 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.
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 dental inlays has following advantages:
- Safe for the patient
- The smooth and polished surface repels plaque deposition on their surfaces.
- Ceramic and gold inlays have remarkable mechanical resistance to wear.
- Accurate fit and bonding of the onlays to the tooth leaves no microgaps between the tooth and restoration, minimizing the chances of tooth sensitivity and secondary tooth decay.
- Xerox copy of the tooth preparation.
- Doesn’t discolour
- Seals the tooth and reduces the risk of root canal failure, a problem associated with composite and amalgam fillings.
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.
- The ceramic may fracture in a small cavity.
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 good oral hygiene is maintained. However, failure may occur due to fracture of the restoration or 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 or onlay. Roughly, they cost between $500-$1200. However, the cost varies with the type of chosen material.
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Does getting an inlay hurt?
No, inlays don’t normally hurt. However, deep cavities close to pulp may hurt and cause sensitivity in the teeth. The pain usually goes away in 7-14 days.
How long after an inlay can I eat?
Refrain from eating until the numbness goes away. Eat a soft diet during the first 24 hours. Avoid eating from the side where the filling has been placed and give periodontium (tooth supporting tissues) time to heal. If there is no sensitivity, Regular diet can be resumed 24 hours after the filling, if there is no sensitivity,
How long are teeth sensitive after inlay?
Cavity preparation in a cavity close to pulp may trigger pain or sensitivity in the tooth that may last upto 7-14 days. The fibration from high-speed dental drill and intrumentation may irritate the nerve fibers extending into the dentin resulting in tooth sensitivity.
Summary
The dental inlays are custom fillings used for severely damaged and decayed premolars or molars. An impression of the prepared tooth is used to make inlays and onlay in the lab. The prepared inlays and onlays are checked for accuracy and bonded to the tooth. Composite resins, ceramics, or gold are the material of choice for inlays and onlays.