Understanding the Difference Between Inlays and Onlys

by | Jan 23, 2020 | Cosmetic Dentistry Blogs

What is the Difference Between Inlays and Fillings?

You are probably familiar with the idea of having a filling. However, you may be less aware of the different types and when they are used. Not only can you have a standard filling, but you can also have an inlay or onlay. While all types of filling are essentially a way to remove a cavity and fill the empty space, the way they are done and the materials used differ. The question is, if you have a cavity, what is the best treatment for you?

What Are Fillings?

Chances are you have already had at least a couple of fillings. They are a great way to repair small to medium-sized cavities, areas of decay in your teeth, and are a popular treatment method. Traditionally, fillings used silver amalgam, making them much more noticeable in your mouth. Today, however, modern fillings more commonly use composite resin, which is almost invisible once placed. As well as its colour, the composite resin material has several benefits; it works in harmony with the natural tooth structure, requires less tooth to be removed and forms a tighter seal.

When you have a filling placed, it is a relatively quick procedure. The decayed part of your tooth will be removed, and the filling placed, all during one appointment. This makes a standard filling a direct restoration, the material is available and the treatment is carried out in one visit. What’s more, treatment can be used to repair damage to both front and back teeth, and the results are excellent and long-lasting. So, why would you need any other type of filling?

When Might You Need an Inlay?

The large chewing surfaces on our back teeth contain quite deep fissures, which make it easy for plaque and food to get trapped and cavities to form. When there is a cavity in the back teeth, sometimes conventional fillings aren’t strong enough. Inlays leave the healthy tooth structure intact and can help to prevent the expense of root canal treatment or extraction in the future.

The process of getting an inlay is different from that of a filling as it is an indirect restoration, that requires more than one visit. The tooth needs to be carefully prepared and a detailed impression taken. The impression is used to create a model of the tooth that is then sent to a laboratory to individually craft a single porcelain restoration. Once the inlay has been made, it is then cemented onto the prepared tooth surface.

Porcelain is used for inlays instead of the composite resin of conventional fillings, however, it is similar in its ability to remain durable, strong and almost undetectable. In fact, inlays are incredibly strong due to being created in a laboratory, they are made to fit perfectly and contract less than conventional fillings once placed. This means there is much less of a seam between the restoration and the tooth, keeping further decay at bay, and your teeth are able to withstand greater chewing forces.

What Are Onlays?

Just to confuse matters further, there is also the possibility of your dentist recommending an onlay. Onlays are similar to inlays, but a little larger. They are a suitable option if you have decay in the central part of the chewing surface as well as one or more of the tooth cups, the raised points of your teeth.

Onlays are a more expensive single-tooth restoration treatment, reserved for larger areas of decay where a filling or inlay wouldn’t be sufficient. The main difference between onlays and inlays is that onlays cover the cusp of the tooth. However, the process is very similar, the cavity will be removed, impressions made and a porcelain restoration created in the laboratory.

How to Know Which Treatment is Right for You?

The best way to know whether you need a filling, an inlay or onlay, is to speak with your dentist. If you only have a small cavity, a filling will probably be the best treatment. If you have a larger cavity within the chewing surfaces of your back teeth, you’ll probably need an inlay. And, if you also have decay on the tooth cusps, an onlay might be the best option. All of the treatments offer their own benefits in terms of length of procedure, durability and prevention of further decay. Whichever treatment is recommended, however, you can have confidence that your tooth will be restored to its full strength and structure so that you can continue as normal.

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