Crowns, Bridges, Onlays, Inlays
Designed to restore appearance and function of teeth that have been thoroughly damaged by decay or trauma, crowns (also called caps) are a common form of restoration. Their name comes from the part of the tooth they cover—the crown or the top—and they are cemented on for durability. When a tooth is almost gone, held together merely by a large filling or so weak that it could break further, a crown serves to prevent further damage and preserve what is there. There are three main types of crowns: full metal, porcelain fused to metal, and all ceramic. For more about crowns, see the chapter on prosthetic dentistry.
In cases where a tooth needs to be replaced, bridgework is one option for restoration. Bridgework involves the creation of prosthetic teeth, which are attached to a crown and then attached to supporting teeth. Usually good for 10 years, bridges provide a reliable way to replace lost or removed teeth, but not all teeth can be replaced this way.
Onlays & Inlays
Specifically made in a laboratory to fit a tooth, onlays and inlays replace lost tooth material. Very costly, these restorations are similar to fillings but larger in size, set into the bumps on the surface of a tooth.
Onlays are larger than inlays, but both can be made of a variety of materials, including gold, composite resin, or ceramics. According to a recent study, ceramic inlays and onlays are particularly beneficial, both in terms of aesthetics and durability, in situations where posterior teeth are especially damaged.
Prevention is always the best option in caring for your teeth; however, when decay does occur, fillings offer an effective method for preventing further damage. They help fill in the biting surface of a decayed tooth after all decay has been removed. Fillings are available in four different materials: amalgam, gold, composite, or porcelain, and each has different pluses and minuses to consider.
Take amalgam (sometimes called silver): though shown for over a century to be a successful and cost-effective filling material, this substance now warrants a lot of controversy. From an environmental standpoint, there is concern about the amount of mercury discharged into wastewater from dental offices. From a health standpoint, there are many who believe the liquid mercury in amalgam can lead to a host of serious medical issues, from multiple sclerosis to hearing loss. Despite these fears, the truth is that no reliable or authoritative studies have been conclusive enough to lead to a national ban on the material. In fact, a 2004 study for the U.S. Public Health Service found “insufficient evidence of a link between dental mercury and health problems, except in rare instances of allergic reaction.” In our generation of prevention, it still makes sense to choose a material you feel most comfortable with; however, the biggest reason we avoid amalgam is a cosmetic one: it’s simply not as attractive as other options.
The most common alternative to amalgam, composite fillings are white, tooth-colored fillings made from resin reinforced with powdered glass.
Benefits of Composite Fillings
The benefits of composite fillings are aesthetics and convenience. Because of their tooth-colored shade, composite fillings blend right in with other teeth, creating the most attractive restoration. They minimize the amount of healthy tooth removal needed, and they are very convenient, able to be applied in just one dental visit.
Disadvantages of Composite Fillings
On the down side, there are some major problems associated with this material, too. Composite is very technique-sensitive: any moisture that contacts the material as it sets can negatively affect the integrity of the filling, leading to recurrent decay. Anecdotally, we have seen hundreds of failed composite fillings with such severe recurrent decay that the teeth often need root canals. Additionally, there has been some recent talk of composite fillings leaking bisphenol A (BPA), a chemical shown in animal testing to increase risk for heart health issues, cancer, diabetes, sexual dysfunction, and hyperactivity.
Based on a thorough understanding of composite materials, it is our recommendation that composite only be used in shallow cavities that can be properly isolated during the placement so no moisture gets in, and all of the margins of the filling are accessible and visible to ensure a tight seal.
Gold fillings are a durable filling option used to restore decay on a tooth’s biting surface. Created from a combination of gold, copper, and other metals, gold alloy has been used for quite a while and doesn’t fracture under stress.
Benefits of Gold Fillings
What makes gold fillings a good choice is their time-tested, established use. Gold doesn’t corrode in the mouth, and it wears well. Also, as a soft metal, gold conforms to the walls of the filling and causes a stable seal. When gold fillings are fitting properly, they offer excellent resistance to further decay.
Disadvantages of Gold Fillings
On the other hand, gold fillings aren’t exactly ideal. They have to be made in a lab and require at least two visits to implement, making them inconvenient and costly. They can irritate sensitive teeth, particularly in response to hot and cold because of how the metal conducts temperatures. Plus, because gold fillings don’t match teeth in color but are rather yellow, they are not as aesthetically pleasing as other options.
A glassy, tooth-colored material, porcelain is yet another filling option. Porcelain fillings are made in a dental lab from an impression and usually reserved for larger fillings such as onlays and inlays.
Benefits of Porcelain Fillings
Porcelain fillings offer beautiful aesthetics with their tooth-colored appearance and customized fit. The new metal-free material lithium disilicate (IPS e.max) offers a fresh take on porcelain fillings. According to a recent study, clinical trials for the last four years have yielded very positive findings regarding this strong and versatile material, which was determined to be one of the best restorative materials available.
Disadvantages of Porcelain Fillings
The downside of porcelain fillings is the cost, as well as the fact that they usually take two visits to implement. However, new digital technology has improved methods of restorations tremendously.
New Technology for Porcelain Fillings
The E4D Dentist CAD Cam system and the Chairside Economical Restoration of Esthetic Ceramics (CEREC) porcelain-milling machine are two new developments improving the way porcelain fillings work.
The E4D allows dentists to create restorations right in the office, without sending things out to a lab and without waiting a long time for a completed product.
Similarly, dental offices that offer an in-house CEREC machine can provide patients with same-day turnaround on porcelain crowns and inlays. This means all the benefits of porcelain fillings—beautiful appearance, easy blend with other teeth, customized fit—without the lengthy wait time or multiple office visits.