Types of Dental Restorations

There are two types of dental restorations: direct and indirect.

Direct restorations are fillings placed immediately into a prepared cavity in a single visit. They include dental amalgam, glass ionomers, resin ionomers and some resin composite fillings. The dentist prepares the tooth, places the filling and adjusts it during one appointment.

Indirect restorations generally require two or more visits. They include inlays, onlays, veneers, crowns and bridges fabricated with gold, base metal alloys, ceramics or composites. During the first visit, the dentist prepares the tooth and makes an impression of the area to be restored. The impression is sent to a dental laboratory, which creates the dental restoration. At the next appointment, the dentist cements the restoration into the prepared cavity and adjusts it as needed.

Amalgam Fillings

Used by dentists for more than a century, dental amalgam is the most thoroughly researched and tested restorative material among all those in use. It is durable, easy to use, highly resistant to wear and relatively inexpensive in comparison to other materials. For those reasons, it remains a valued treatment option for dentists and their patients.

Dental amalgam is a stable alloy made by combining elemental mercury, silver, tin, copper and possibly other metallic elements. Although dental amalgam continues to be a safe, commonly used restorative material, some concern has been raised because of its mercury content. However, the mercury in amalgam combines with other metals to render it stable and safe for use in filling teeth.

While questions have arisen about the safety of dental amalgam relating to its mercury content, the major U.S. and international scientific and health bodies, including the National Institutes of Health, the U.S. Public Health Service, the Centers for Disease Control and Prevention, the Food and Drug Administration and the World Health Organization, among others have been satisfied that dental amalgam is a safe, reliable and effective restorative material.

Because amalgam fillings can withstand very high chewing loads, they are particularly useful for restoring molars in the back of the mouth where chewing load is greatest. They are also useful in areas where a cavity preparation is difficult to keep dry during the filling replacement, such as in deep fillings below the gum line. Amalgam fillings, like other filling materials, are considered biocompatible—they are well tolerated by patients with only rare occurrences of allergic response.

Disadvantages of amalgam include possible short-term sensitivity to hot or cold after the filling is placed. The silver-colored filling is not as natural looking as one that is tooth-colored, especially when the restoration is near the front of the mouth, and shows when the patient laughs or speaks. And to prepare the tooth, the dentist may need to remove more tooth structure to accommodate an amalgam filling than for other types of fillings.

Amalgam (Silver-Colored) Fillings

If my tooth doesn’t hurt and my filling is still in place, why would the filling need to be replaced?

Constant pressure from chewing, grinding or clenching can cause dental fillings, or restorations, to wear away, chip or crack. Although you may not be able to tell that your filling is wearing down, your dentist can identify weaknesses in your restorations during a regular check-up.

If the seal between the tooth enamel and the restoration breaks down, food particles and decay-causing bacteria can work their way under the restoration. You then run the risk of developing additional decay in that tooth. Decay that is left untreated can progress to infect the dental pulp and may cause an abscess.

If the restoration is large or the recurrent decay is extensive, there may not be enough tooth structure remaining to support a replacement filling. In these cases, your dentist may need to replace the filling with a crown.

Are dental amalgams safe?

Yes. Dental amalgam has been used in tooth restorations worldwide for more than 100 years. Studies have failed to find any link between amalgam restorations and any medical disorder. Amalgam continues to be a safe restorative material for dental patients.

Is it possible to have an allergic reaction to amalgam?

Only a very small number of people are allergic to amalgam fillings. Fewer than 100 cases have ever been reported. In these rare instances, mercury may trigger an allergic response. Symptoms of amalgam allergy are very similar to a typical skin allergy.
Often patients who are truly allergic to amalgam have a medical or family history of allergies to metals. If there is a confirmed allergy, another restorative material will be used.

Is it true that dental amalgams have been banned in other countries?

No. Erroneous news reporting has confused restrictions in a few countries with outright bans. Dentists around the world are using dental amalgams (silver fillings) to restore teeth that have dental decay. Studies have not shown a link between dental amalgam and any medical disorder.

Is there a filling material that matches tooth color?

Yes. Composite resins are tooth-colored, plastic materials (made of glass and resin) that are used both as fillings and to repair defects in the teeth. Because they are tooth-colored, it is difficult to distinguish them from natural teeth. Composites are often used on the front teeth where a natural appearance is important. They can be used on the back teeth as well depending on the location and extent of the tooth decay. Composite resins are usually more costly than amalgam fillings.

Composite Fillings

Composite fillings are a mixture of glass or quartz filler in a resin medium that produces a tooth-colored filling.

They are sometimes referred to as composites or filled resins. Composite fillings provide good durability and resistance to fracture in small-to-mid size restorations that need to withstand moderate chewing pressure. Less tooth structure is removed when the dentist prepares the tooth, and this may result in a smaller filling than that of an amalgam.

Composites can also be "bonded" or adhesively held in a cavity, often allowing the dentist to make a more conservative repair to the tooth.

The cost is moderate and depends on the size of the filling and the technique used by the dentist to place it in the prepared tooth. It generally takes longer to place a composite filling than what is required for an amalgam filling. Composite fillings require a cavity that can be kept clean and dry during filling and they are subject to stain and discoloration over time.

Ionomers

Glass ionomers are translucent, tooth-colored materials made of a mixture of acrylic acids and fine glass powders that are used to fill cavities, particularly those on the root surfaces of teeth. Glass ionomers can release a small amount of fluoride that may be beneficial for patients who are at high risk for decay. When the dentist prepares the tooth for a glass ionomer, less tooth structure can be removed; this may result in a smaller filling than that of an amalgam.

Glass ionomers are primarily used in areas not subject to heavy chewing pressure. Because they have a low resistance to fracture, glass ionomers are mostly used in small non-load bearing fillings (those between the teeth) or on the roots of teeth.

Resin ionomers also are made from glass filler with acrylic acids and acrylic resin. They also are used for very small, non-load bearing fillings (between the teeth), on the root surfaces of teeth, and they have low to moderate resistance to fracture.

Ionomers experience high wear when placed on chewing surfaces. Both glass and resin ionomers mimic natural tooth color but lack the natural translucency of enamel. Both types are well tolerated by patients with only rare occurrences of allergic response.

Indirect Restorative Dental Materials (Two or more visits)

Sometimes the best dental treatment for a tooth is to use a restoration that is made in a laboratory from a mold. These custom-made restorations, which require two or more visits, can be a crown, an inlay or an onlay. A crown covers the entire chewing surface and sides of the tooth. An inlay is smaller and fits within the contours of the tooth.

An onlay is similar to an inlay, but it is larger and covers some or all chewing surfaces of the tooth. The cost of indirect restorations is generally higher due to the number and length of visits required, and the additional cost of having the restoration made in a dental laboratory. Materials used to fabricate these restorations are porcelain (ceramic), porcelain fused to a metal-supporting structure, gold alloys and base metal alloys.

All-Porcelain (Ceramic) Dental Materials

All-porcelain (ceramic) dental materials include porcelain, ceramic or glasslike fillings and crowns. They are used as inlays, onlays, crowns and aesthetic veneers. A veneer is a very thin shell of porcelain that can replace or cover part of the enamel of the tooth. All-porcelain (ceramic) restorations are particularly desirable because their color and translucency mimic natural tooth enamel.

All-porcelain restorations require a minimum of two visits and possibly more. The restorations are prone to fracture when placed under tension or on impact. The strength of this type of restoration depends on an adequate thickness of porcelain and the ability to be bonded to the underlying tooth. They are highly resistant to wear but the porcelain can quickly wear opposing teeth if the porcelain surface becomes rough.

Porcelain-fused-to-Metal

Another type of restoration is porcelain-fused-to-metal, which provides strength to a crown or bridge. These restorations are very strong and durable. The combination of porcelain bonded to a supporting structure of metal creates a stronger restoration than porcelain used alone. More of the existing tooth must be removed to accommodate the restoration.

Although they are highly resistant to wear, porcelain restorations can wear opposing natural teeth if the porcelain becomes rough. There may be some initial discomfort to hot and cold. While porcelain-fused-to-metal restorations are highly biocompatible, some patients may show an allergic sensitivity to some types of metals used in the restoration.

Gold Alloys

Gold alloys contain gold, copper and other metals that result in a strong, effective filling, crown or a bridge. They are primarily used for inlays, onlays, crowns and fixed bridges. They are highly resistant to corrosion and tarnishing.

Gold alloys exhibit high strength and toughness that resists fracture and wear. This allows the dentist to remove the least amount of healthy tooth structure when preparing the tooth for the restoration. Gold alloys are also gentle to opposing teeth and are well tolerated by patients. However, their metal colors do not look like natural teeth.

Base Metal Alloys

Base metal alloys are non-noble metals with a silver appearance. They are used in crowns, fixed bridges and partial dentures. They can be resistant to corrosion and tarnishing. They also have high strength and toughness and are very resistant to fracture and wear.

Some patients may show allergic sensitivity to base metals and there may be some initial discomfort from hot and cold. However, due to their metal color, gold alloys do not look like natural teeth.

Indirect Composites

Crowns, inlays and onlays can be made in the laboratory from dental composites. These materials are similar to those used in direct fillings and are tooth colored. One advantage to indirect composites is that they do not excessively wear opposing teeth.

Their strength and durability is not as high as porcelain or metal restorations and they are more prone to wear and discoloration.

Did you know that dental implants are frequently the best treatment option for replacing missing teeth? Rather than resting on the gum line like removable dentures, or using adjacent teeth as anchors like fixed bridges, dental implants are long-term replacements that your oral and maxillofacial surgeon surgically places in the jawbone.

A Solution of Choice for Replacing Missing Teeth

Statistics show that 69% of adults ages 35 to 44 have lost at least one permanent tooth to an accident, gum disease, a failed root canal or tooth decay. Furthermore, by age 74, 26% of adults have lost all of their permanent teeth.

Twenty years ago, these patients would have had no alternative but to employ a fixed bridge or removable denture to restore their ability to eat, speak clearly and smile. Fixed bridges and removable dentures, however, are not the perfect solution and often bring with them a number of other problems. Removable dentures may slip or cause embarrassing clicking sounds while eating or speaking. Of even greater concern, fixed bridges often affect adjacent healthy teeth, and removable dentures may lead to bone loss in the area where the tooth or teeth are missing. Recurrent decay, periodontal (gum) disease and other factors often doom fixed bridgework to early failure. For these reasons, fixed bridges and removable dentures usually need to be replaced every seven to 15 years.

Before (left) and after a dental implant.

Today there is another option for patients who are missing permanent teeth. Rather than resting on the gum line like removable dentures, or using adjacent teeth as anchors like fixed bridges, dental implants are long-term replacements that your oral and maxillofacial surgeon surgically places in the jawbone. Composed of titanium metal that "fuses" with the jawbone through a process called "osseointegration," dental implants never slip or make embarrassing noises that advertise the fact that you have "false teeth," and never decay like teeth anchoring fixed bridges. Because dental implants fuse with the jawbone, bone loss is generally not a problem.

After more than 20 years of service, the vast majority of dental implants first placed by oral and maxillofacial surgeons in the United States continue to still function at peak performance. More importantly, the recipients of those early dental implants are still satisfied they made the right choice. If properly cared for, dental implants can last a lifetime.

Anatomy of a Dental Implant

A dental implant designed to replace a single tooth is composed of three parts: the titanium implant that fuses with the jawbone; the abutment, which fits over the portion of the implant that protrudes from the gum line; and the crown, which is created by a prosthodontist or restorative dentist and fitted onto the abutment for a natural appearance. Many people who are missing a single tooth opt for a fixed bridge; but a bridge may require the cutting down of healthy, adjacent teeth that may or may not need to be restored in the future. Then there is the additional cost of possibly having to replace the bridge once, twice or more over the course of a lifetime. Similarly, a removable partial denture may contribute to the loss of adjacent teeth. Studies show that within five to seven years there is a failure rate of up to 30% in teeth located next to a fixed bridge or removable partial denture.

Fixed bridges may require the shaping or cutting down of adjacent healthy teeth.	Bone is maintained by the presence of natural teeth or implants (a). Bone loss occurs with the loss of teeth (b).

Further, conventional dentures may contribute to the loss of bone in the area where teeth are missing. As illustration (a) indicates, the presence of natural teeth preserves the jawbone. When a tooth is missing, as in illustration (b), the bone may erode and weaken until it may be necessary for your oral and maxillofacial surgeon to graft bone to the area to strengthen it for placement of a dental implant. When a missing tooth is replaced by a dental implant, the fusion, or osseointegration, of the implant and bone provides stability, just as the natural tooth did.

If you are missing several teeth in the same area of your mouth, you may still enjoy the confidence and lifestyle benefits that come with dental implants. Your oral and maxillofacial surgeon will place two or more dental implants, depending on the number of teeth that are missing. Your replacement teeth will be attached to the implants to allow excellent function and prevent bone loss. The implants will serve as a stable support that tightly locks into your replacement teeth and dentures to prevent slipping and bone loss.

With an overall success rate of about 95% and almost 50 years of clinical research to back them up, dental implants are frequently the best treatment option for replacing missing teeth.

Dental Implants vs. Conventional Dentures

Many patients who have selected dental implants describe a quality of life that is much more comfortable and secure than the lifestyle endured by those with fixed bridges or removable dentures. Dentures often make a person feel and look older than they are, cause embarrassment in social situations when they slip and click, and restrict the everyday pleasure of eating comfortably. When they count the benefits they enjoy as a result of their dental implants, patients say their implants eliminate the day-to-day frustrations and discomfort of ill-fitting dentures. They allow people to enjoy a healthy and varied diet without the restrictions many denture wearers face. With a sense of renewed self-confidence, many people rediscover the excitement of an active lifestyle shared with family and friends and the chance to speak clearly and comfortably with co-workers. For all these reasons, people with dental implants often say they feel better... they look better... they live better.

Implants can be used to replace one missing tooth so that the replacement looks and feels natural (a). Also, two or more implants can serve as a stable support for the replacement of many teeth (b).

Dental Implants are a Team Effort

Dental implants combine the best of modern science and technology, including a team approach spanning several disciplines.

A successful implant requires that all parties involved — the patient; the restorative dentist, who makes the crown for the implant; and the oral and maxillofacial surgeon, who surgically places the implant, follow a careful plan of treatment. All members of the implant team stay in close contact with each other to make sure everyone clearly understands what needs to be done to meet the patient's expectations.

The team is organized as soon as the decision for placing a dental implant is reached. Following an evaluation that includes a comprehensive examination, x-rays and a consultation with the patient and members of the implant team, the oral and maxillofacial surgeon surgically places the posts, or implants, in the patient's jaw.

When the implants have stabilized in the jaw, the restorative dentist prepares an impression of the upper and lower jaws. This impression is used to make the model from which the dentures or crowns are created.

The teamwork continues long after the implant and crown have been placed. Follow-up examinations with the oral and maxillofacial surgeon and restorative dentist are critical, and progress is carefully charted. Both the oral and maxillofacial surgeon and the restorative dentist continue to work together to provide the highest level of aftercare.

Are You a Candidate for Dental Implants?

Whether you are a young, middle-aged or older adult; whether you need to replace one tooth, several teeth, or all your teeth, there is a dental implant solution for you. With the exception of growing children, dental implants are the solution of choice for people of all ages, even those with the following health concerns:

Existing Medical Conditions. If you can have routine dental treatment, you can generally have an implant placed. While precautions are advisable for certain conditions, patients with such chronic diseases as high blood pressure and diabetes are usually successful candidates for dental implant treatment.

Gum Disease or Problem Teeth. Almost all implants placed in patients who have lost their teeth to periodontal disease or decay have been successful.

Currently Wearing Partials or Dentures. Implants can replace removable bridges or dentures, or they can be used to stabilize and secure the denture, making it much more comfortable.

Smokers. Although smoking lowers the success rate of implants, it doesn't eliminate the possibility of getting them.

Bone Loss. Bone loss is not uncommon for people who have lost teeth or had periodontal disease. Oral and maxillofacial surgeons are trained and experienced in grafting bone to safely and permanently secure the implant.

Implant tooth replacement in children is usually deferred until their jaw growth is complete. There are, however, some instances when a dental implant may be appropriate, such as when it is part of the child's orthodontic treatment plan. Your family dentist or orthodontist can guide you in this instance.