Inlays vs. Onlays

Modern dentistry has quickly evolved to impact the way we think about options for tooth fillings. In previous decades, mercury was a common choice for filling in damage and decay. In fact, the procedure was so normal that it has been used around the world for more than 150 years. When mixed with a powdered alloy of silver, tin, and copper, mercury is useful for binding materials together for a durable filler. Although fillings with mercury are strong, long-lasting, and affordable, the FDA notes that high levels of mercury vapor exposure are associated with adverse effects in the brain and kidneys, and sometimes older, or poorly done fillings can be connected to those concerns.

Today, most dentists and patients gravitate toward porcelain or white fillings in the event that one is needed. But there are still many adults walking around Briarwood, Great Neck, and New York in general with older, mercury-connected fillings. If you are one of them, don’t panic! If your fillings are in good condition and have little decay, it’s not necessarily important that they are immediately removed and replaced. If, however, your fillings are wearing down, it might be time to consider an inlay or onlay to replace them and keep you safe and healthy. 

Many patients in our offices are curious about the difference between inlays and onlays. After all, they sound very similar and, indeed, have similar results. Below, we break down the distinctions between the two options. If you have additional questions about what is best for you and your mouth, we would be happy to set up a consultation or discuss it during your next scheduled appointment.


Inlays are pre-molded fillings that fit into the grooves of your teeth but do not extend over the cusp of your tooth. Think of it like filling in a valley, but stopping once you reach the peak. During the inlay process, we apply a topical anesthetic and drill into your damaged tooth to remove previous fillings and any additional decay that remains or has been identified. We work with state-of-the-art laboratories to manufacture a modern filling material created from porcelain, resin, or even gold. Today’s options can be quite discreet, and your preferences will be taken into consideration when we chat during your appointments. Inlays are particularly helpful when your break, fracture, or decay is limited to only a portion of your tooth and when your damaged tooth cannot support a larger filling but is not extensive enough to need a crown.


Onlays play a similar role in preventing further decay, but they are reserved for more advanced damage that impacts a larger amount of your tooth, including the biting surface. Imagine that same valley mentioned before, but instead of stopping filling at the top, a little extra is distributed over the edges and on the topical area at the peak, where you chew on foods. 

In both situations, inlays and onlays can both be your approach to filling in damaged areas of teeth and reducing your risk of more trouble in the future. The process can also prevent unnecessary mercury absorption and allow your smile to look more natural. If old, worn-down fillings are stopping you from having a smile that you love, inlays and onlays are helpful options, and both are easily obtainable through our offices.

It’s important that you are both free from pain and confident in your smile. When you are ready to take the next step and move toward a new filling option, we’re here to help! Give us a call today or fill out a contact form to start the process.