Types of Dental Filling Materials

To treat a cavity your dentist will remove the decayed portion of the tooth and then "fill" the area on the tooth where the decayed material once lived.
Fillings are also used to repair cracked or broken teeth and teeth that have been worn down from misuse (such as from nail-biting or tooth grinding ).

Today, several dental filling materials are available. Teeth can be filled with gold; porcelain; silver amalgam (which consists of mercury mixed with silver, tin, zinc, and copper); or tooth-colored, plastic and glass materials called composite resin fillings. The location and extent of the decay, cost of filling material, patients' insurance coverage and your dentist's recommendation assist in determining the type of filling that will best address your needs.

Cast gold

Advantages:

    Durability - lasts at least 10 to 15 years, usually longer; doesn't corrode
    Strength - can withstand chewing forces
    Aesthetics - some patients find gold more pleasing to the eye than silver, amalgam fillings

Disadvantages:

    Expense - more than other materials; up to 10 times higher than cost of amalgam filings
    Additional office visits - requires at least two office visits to place
    Galvanic shock - a gold filling placed immediately next to a silver, amalgam filling can cause a sharp pain (galvanic shock) to occur. The interaction between the metals and saliva causes an electric current to occur - it's a rare occurrence, however
    Aesthetics - most patients don't find any "colored" fillings to be an "eye-pleasing" advantage

Silver-fillings (Amalgams)

Advantages:

    Durability - lasts at least 10 to 15 years and usually outlasts composite fillings
    Strength - can withstand chewing forces
    Expense - is less expensive than composite fillings

Disadvantages:

    Poor aesthetics - fillings don't match the color of your natural teeth
    Destruction of more tooth structure - healthy parts of the tooth must often be removed to make a space large enough to hold the amalgam filling
    Discoloration - amalgam fillings can create a grayish hue to the surrounding tooth structure
    Cracks and fractures - although all teeth expand and contract in the presence of hot and cold liquids, which ultimately can cause the tooth to crack or fracture, amalgam material - in comparison with other filling materials-may experience a wider degree of expansion and contraction and lead to a higher incidence of cracks and fractures
    Allergic reactions - a small percentage of people, approximately 1%, are allergic to the mercury present in amalgam restorations

Tooth-colored composite fillings

Advantages:

    Aesthetics - the shade/color of the composites can be closely matched to the color of existing teeth; is particularly well suited for use in front teeth or visible parts of teeth
    Bonding to tooth structure - composite fillings actually chemically bond to tooth structure, providing further support to the tooth
    Versatility in uses - in addition to use as a filling material for decay, composite fillings can also be used to repair chipped, broken or worn teeth
    Tooth-sparing preparation - sometimes less tooth structure needs to be removed compared with amalgams when removing decay and preparing for the filling

Disadvantages:

    Lack of durability - composite fillings wear out sooner than amalgams (lasting at least 5 years compared with at least 10 to 15 for amalgams); in addition, they may not last as long as amalgams under the pressure of chewing and particularly if used as the filling material for large cavities
    Increased chair time - because of the process to apply the composite material, these fillings can take up to 20 minutes longer than amalgams to place
    Additional visits - if composites are used for inlays or onlays, more than one office visit may be required
    Chipping - depending on location, composite materials can chip off the tooth
    Expense - composite fillings can cost up to twice the cost of amalgams

In addition to tooth-colored, composite resin fillings, two other tooth-colored fillings exist--ceramics and glass ionomer.

Other

    Ceramics, which are made most often of porcelain, are more resistant to staining than composite resin material but are also more abrasive. This material generally lasts more than 15 years and can cost as much as gold.
    Glass ionomer is made of acrylic and a specific type of glass material. This material is most commonly used for fillings below the gum line and for fillings in young children (drilling is still required). Glass ionomers release fluoride, which can help protect the tooth from further decay. However, this material is weaker than composite resin and is more susceptible to wear and prone to fracture. Glass ionomer generally lasts 5 years or less with costs comparable to composite resin.

What Are Indirect Fillings?

Indirect fillings are similar to composite or tooth-colored fillings except that they are made in a dental laboratory and require two visits before being placed. Indirect fillings are considered when not enough tooth structure remains to support a filling but the tooth is not so severely damaged that it needs a crown.

During the first visit, decay or an old filling is removed. An impression is taken to record the shape of the tooth being repaired and the teeth around it. The impression is sent to a dental laboratory that will make the indirect filling. A temporary filling (described below) is placed to protect the tooth while your restoration is being made. During the second visit, the temporary filling is removed, and the dentist will check the fit of the indirect restoration. Provided the fit is acceptable, it will be permanently cemented into place.

There are two types of indirect fillings - inlays and onlays.

    Inlays are similar to fillings but the entire work lies within the cusps (bumps) on the chewing surface of the tooth.
    Onlays are more extensive than inlays, covering one or more cusps. Onlays are sometimes called partial crowns.

Inlays and onlays are more durable and last much longer than traditional fillings - up to 30 years. They can be made of tooth-colored composite resin, porcelain, or gold. Inlays and onlays weaken the tooth structure, but do so to a much lower extent than traditional fillings.

Another type of inlay and onlay - direct inlays and onlays - follow the same processes and procedures as the indirect, the difference is that direct inlays and onlays are made in the dental office and can be placed in one visit. The type of inlay or onlay used depends on how much sound tooth structure remains and consideration of any cosmetic concerns.