Nargiz I. Zadeh, DMD
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Inlays and Onlays: What's the Difference?

July 27, 2021
Posted By: Dr. Nargiz I. Zadeh, DMD

When we talk about dental restorations, we usually focus on fillings and crowns. Not many people know about the restorations that fall in between—the “inlays” and “onlays”—yet these are also great options for restoring your teeth in a conservative and esthetic way. In this post, we will discuss these individual treatment options in more detail, how they compare to crowns, and when your dentist might suggest them.

What Are Dental Inlays?

Inlays are like dental fillings in many aspects but are used when a cavity is too large to hold a filling. The main difference is that inlays are made by a dental laboratory as a single unit that is cemented onto the tooth. In contrast, a filling is made directly on the tooth by the dentist layering and sculpting a composite material that hardens when a blue spectrum light is shined on it.

Since the inlay is made by a dental lab, it requires two appointments to complete. During the first visit, your dentist will clean out the decayed part of the tooth and take a mold of the space that has been carved out. This mold is sent to the dental lab for fabrication of the inlay out of a ceramic material. On the second visit, your dentist will use a permanent cement to bond the inlay to the tooth. Inlays are great conservative, and predictable options for treating teeth with larger cavities; instances where regular fillings cannot last as long. However, inlays are typically more expensive due to being more technique sensitivity. So, it’s beneficial to weigh the pros and cons of doing a filling or inlay when deciding which one to choose.

Related post: Nargiz I. Zadeh, DMD Blog | When is a Filling the Right Choice for a Cavity? 

What is a Dental Onlay?

Onlays are restorations that replace a larger portion of the tooth than inlays would, but smaller than crowns would. They are used when the tooth has a cavity or crack causing one or two cusps to be removed. In this instance, a filling or inlay would not hold in the tooth while a crown would result in unnecessary removal of too much tooth structure. Therefore, an onlay would be the most ideal option. The process for doing an onlay is identical to an inlay or a crown; it is a two-appointment procedure at the end of which the onlay is permanently cemented on the tooth.

Now, a quick lesson on the anatomy of our teeth. When referring to “cusps”, as I did above, I am describing the mountain-like, sharp points that stick out of our teeth. These are the areas that we use to chew, so they experience a lot of mechanical stress. An onlay or crown help to replace missing cusps, while an inlay would not. So, we gauge which restoration would work best based on the amount, or lack of, missing cusps.

What's the Difference Between an Onlay and a Crown?

In basic terms, a crown is a more extensive type of onlay that is appropriate to treat damaged teeth requiring significant mechanical support and protection. Unlike an onlay, which only covers a portion of the tooth, a crown covers the entire tooth. So, in instances where a patient grinds his teeth a lot, or has a history of breaking multiple teeth, a crown might be the best option. In another example, your dentist may tell you that an onlay could successfully restore the affected tooth, but she can’t guarantee this. Why would you want to do onlay in this instance as opposed to crown? Well, even if an onlay only lasts a few years, it will still conserve more tooth structure than a crown, and when it needs to be replaced you then can replace it with a crown.

Remember that every situation is different, and your dentist has years of experience understanding which options will work in which situations. In my professional opinion, the goal should always be to conserve as much natural tooth structure as possible, so buying a few more years with a conservative treatment before jumping straight to a crown is often beneficial. Nevertheless, you should trust that your dentist will present you with all the options that are suitable for your dental condition.

Related post: Dental Crowns Can Restore Your Teeth and Smile 

Finding Help to Explore Your Options In-Depth

Tooth damage can lead to much bigger problems when you leave it untreated. So, a situation that could require an inlay at one point may turn into a larger problem requiring a crown in a few months. Remember to stay current with your dental visits and try to not delay treatment. With years of successful treatments, Dr. Nargiz I. Zadeh can provide you with helpful ways to restore oral health, and we will discuss your treatment options in a comfortable and welcoming environment. Schedule a visit at your convenience today.

Testimonial from Leah, Satisfied Patient 

Friendly and painless dental office. You don't need to look anywhere else. Debbie at the front desk is kind and considerate. Always a pleasure to see. Getting your teeth cleaned by their knowledgeable technicians is a breeze and dentist Nargiz Zadeh is professional, personable and empathetic with the lightest touch.