Onlays are recommended when a tooth is too damaged to support a dental filling but not damaged enough for a dental crown. Dental Onlays and Inlays are the same kind of restoration but cover different areas of the tooth. A Dental Inlay fills the space in-between the cusp or rounded edges at the center of the tooth surface. A Dental Onlay works the same but covers one or more cusps of the entire biting surface, sometimes known as “partial crowns”. Dental Onlays are more durable and usually last longer than dental fillings. If cared for properly, a Dental Onlay can last up to 30 years!