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 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 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 fillings.
- 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 and fractures.
- 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.
Other Filling Types
- Ceramics — These fillings 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 five years or less with costs comparable to composite resin.