Tooth restorations are the various ways your dentist can replace missing teeth or repair missing parts of the tooth structure. Tooth structure can be missing due to decay, deterioration of a previously placed restoration, or fracture of a tooth. Examples of restorations include the following:
Fillings are the most common type of dental restoration. Teeth can be filled with gold, silver amalgam, or tooth-colored plastic materials called composite resin fillings.
Crowns are a tooth-shaped “cap” that is placed over a tooth to restore its shape and size, strength, appearance, to hold a bridge in place or cover a dental implant.
Bridges are false teeth that are designed to “bridge” the gap created by one or more missing teeth. Bridges can be anchored on either side by crowns and cemented permanently into place.
Implants are replacement tooth roots. Implants are actually a small post made of metal that are placed into the bone socket where teeth are missing. The implant is covered with a replacement tooth called a crown.
Dentures are a removable replacement for missing teeth and surrounding tissues. They are made of acrylic resin sometimes combined with metal attachments. Complete dentures replace all the teeth; partial dentures are considered when some natural teeth remain and are retained by metal clasps attached to the natural teeth.
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 was removed.
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).
What Steps Are Involved in Filling a Tooth?
First, the dentist will use a local anesthetic to numb the area around the tooth to be filled. Next, a drill, air abrasion instrument, or laser will be used to remove the decayed area. The choice of instrument depends on the individual dentist’s comfort level, training, and investment in the particular piece of equipment as well as location and extent of the decay.
Next, your dentist will probe or test the area to determine if all the decay has been removed. Once the decay has been removed, the dentist will prepare the space for the filling by cleaning the cavity of bacteria and debris. If the decay is near the root, your dentist may first put in a liner made of glass ionomer, composite resin, or other material to protect the nerve. Generally, after the filling is in, your dentist will finish and polish it.
Several additional steps are required for tooth-colored fillings and are as follows. After your dentist has removed the decay and cleaned the area, the tooth-colored material is applied in layers. Next, a special light that “cures” or hardens each layer is applied. When the multilayering process is completed, the dentist will shape the composite material to the desired result, trim off any excess material, and polish the final restoration.
What Types of Filling Materials Are Available?
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 materials called composite resin fillings. There is also a material that contains glass particles and is known as glass ionomer. This material is used in ways similar to the use of composite resin fillings.
The location and extent of the decay, cost of filling material, your insurance coverage, and your dentist’s recommendation assist in determining the type of filling best for you.
Cast Gold Fillings
Advantages of cast gold fillings:
Durability — lasts at least 10 to 15 years and 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 of cast gold fillings:
Expense — gold cast fillings cost more than other materials; up to 10 times higher than cost of silver 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 may 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 dislike metal “colored” fillings and prefer fillings that match the rest of the tooth.
Silver Fillings (Amalgams)
Advantages of silver fillings:
Durability — silver fillings last at least 10 to 15 years and usually outlasts composite (tooth-colored) fillings.
Strength — can withstand chewing forces
Expense — is less expensive than composite fillings
Disadvantages of silver fillings:
Poor aesthetics — silver fillings don’t match the color of 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 andfractures.
Allergic reactions — a small percentage of people, approximately 1%, are allergic to the mercury present in amalgam restorations.
Advantages of composites:
Aesthetics — the shade/color of the composite fillings can be closely matched to the color of existing teeth. Composites are 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.
Versatility — 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 amalgam fillings when removing decay and preparing for the filling.
Disadvantages of composites:
Lack of durability — composite fillings wear out sooner than amalgam fillings (lasting at least five years compared with at least 10 to 15 for amalgams); in addition, they may not last as long as amalgam fillings under the pressure of chewing and particularly if used 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 amalgam fillings 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 amalgam fillings.
In addition to tooth-colored, composite resin fillings, two other tooth-colored fillings exist — ceramics and glass ionomer.