Fillings are used to “fill” the area on the tooth where the dentist has removed the decayed portion of the tooth to treat a cavity or to repair cracked or broken teeth and teeth that have been worn down from misuse.
First, a dentist will remove the decayed area with a drill, air abrasion instrument or laser. Then he/she will prepare the space for the filling by cleaning the cavity of bacteria and debris.
If the decay is near the root, a dentist will first put in a liner made of glass ionomer, composite resin, or other material to protect the nerve.
The filling is applied in layers and hardened with a special light. At the end, the dentist will fill, trim off any excess material and polish the tooth.
Available now are several dental filling materials:
- Silver amalgam (which consists of mercury mixed with silver, tin, zinc, and copper)
- Tooth-colored, plastic and glass materials (composite resin fillings)
The dentist will recommend the filling based on the location and extent of the decay, the cost of filling material and patients' insurance coverage.
The advantages of cast gold are:
- Durability (10-15 years)
- Strength and aesthetics (some patients prefer gold than silver amalgam fillings)
The disadvantages of cast gold are:
- Expense (up to 10 times higher than cost of amalgam fillings, additional office visits (at least two office visits to place)
- Galvanic shock (it cannot be placed immediately next to silver because the interaction cause the pain)
- Aesthetics (most patients don't like any "colored" fillings)
The advantages of silver fillings (amalgams) are:
- durability (10-15 years),
- strength and expense (less expensive than composite fillings).
The disadvantages of silver fillings are:
- poor aesthetics (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),
- cracks and fractures (all teeth expand and contract in the presence of hot and cold liquids so this can cause crack or fracture of amalgam)
- allergic reactions (on mercury in amalgam restorations but in a small percentage of people).
The advantages of tooth-colored composite fillings are:
- aesthetics (the shade/color can be closely matched to the color of existing teeth, suited for use in front teeth or visible parts of teeth)
- bonding to tooth structure (chemical bond to tooth structure)
- versatility in uses (can be used to repair chipped, broken or worn teeth)
- tooth-sparing preparation (less tooth structure needs to be removed compared with amalgams)
The disadvantages of tooth-colored composite fillings are:
- lack of durability (5 years)
- increased chair time (20 minutes longer than amalgams)
- additional visits
- chipping (depending on location, composite materials can chip off the tooth)
- expense (cost up to twice the cost of amalgams)
Ceramics (most often of porcelain) are more resistant to staining than composite resin material but are also more abrasive. It lasts more than 15 years and can cost as much as gold.
Temporary fillings are used for fillings that require more than one appointment, following a root canal, to allow a tooth's nerve to "settle down" if the pulp became irritated and if emergency dental treatment is needed (such as to address a toothache).
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. They 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.
There are two types of indirect fillings:
- Inlays (similar to fillings but the entire work lies within the cusps on the chewing surface of the tooth)
- Inlays (more extensive than inlays, covering one or more cusps, sometimes called partial crowns)