Onlays and Inlays

Onlays or inlays are white fillings made of white porcelain that can serve to restore a missing part of a tooth. They are made outside of the patient’s mouth by skilled dental lab technicians, and are an aesthetic solution to cracked teeth or teeth with decay. The best way to think of an onlay is like a puzzle piece that perfectly fills the missing part of the picture of a tooth. They restore teeth to natural contours and shapes as precisely as possible. The missing tooth structure may be due to either dental decay or dental trauma (i.e., impacts, falls, accidents).

Historically, onlays and inlays have been made of metals, typically a gold alloy, but recently are manufactured of high-quality, high-aesthetic porcelains. A typical material is e.Max (lithium dislocate), which is strong, looks natural, and has the ability to bond to tooth structure. Dr. Yuriy Yakubov, DDS, believes that porcelain inlays and onlays are the ideal aesthetic solution for teeth and can be better-looking and longer-lasting than traditional white dental fillings.

Inlays are usually used for small-to-medium sized dental decay or defects. They fill the inside of a tooth but do not cover tooth’s visible, outer surfaces. Onlays, on the other hand, are used for medium-to-large defects and cover the cusps of teeth completely from the top. These serve as the roof over a tooth and allow the distribution of dental forces evenly; this prevents stress accumulation in the tooth and tooth fracture and chipping.

Stress typically accumulates from occlusal chewing forces. Our chewing muscles can generate up to 900 pounds of pressure in the back of the jaw (near the molars) and repeated stress can easily break teeth. This is why onlays may be ideal restorations over root-canal-treated teeth, or teeth with very little structure remaining after the removal of dental decay.

Onlays may be alternatives to dental crowns. Dr. Yuriy Yakubov believes in onlays because there is less preparation of teeth and more preservation of critical tooth structure.

Advantages of Onlays and Inlays

There are several advantages over conventional dental fillings or crowns:

(1) Onlays and inlays last longer than fillings and crowns — up to 35 years for onlays, compared to up to 10 years for fillings or crowns.
(2) They have a better seal between the restoration and tooth than crowns if used with bonding cements.
(3) Onlays and inlays do not shrink during setting as white fillings do. This ensures no gaps between the tooth and restoration, resulting in less continued decay.
(4) They do not expand with time as silver fillings do and can prevent tooth fracture.
(5) Inlays and onlays require less removal of tooth structure than filling and crown preparations.
(6) Onlays look better in the mouth than fillings, and will not change color even years after placement.
(7) Onlays can create an ideal contact with adjacent teeth.
(8) Onlays may prevent inflammation of the gums because they do not hang over the gum and trap plaque and bacteria.
(9) Onlays have higher polish where they meet the gum and are more easily maintained.