A dental filling is usually a two-part step. It is first the removal of decaying tooth matter, caused by cavities, or alternately, the removal of damaged tooth matter caused by injury. Secondly, the dentist applies different materials, to fill the removed portion of the tooth, which allows the person to have full function of that tooth.

In some cases, tooth decay is so severe, that a crown must be constructed outside of the mouth, which is then fit onto the tooth. This is called indirect restoration. Most commonly, though, the dental filling occurs completely in the mouth, called direct restoration, without need for molds, crowns or bridges to be placed.

The first part of the dental filling is often the most uncomfortable and most dreaded by patients. Dentists normally have to drill into a tooth to get to and excise decaying portions of the tooth. Generally, dentists use novocaine to numb the sensation of having the drill applied to the tooth, but both the sound and smell of the dental drill is enough to cause anxiety in many patients. Some patients have adverse reactions to novocaine, and go without it during drilling. The procedure is described as somewhat to very painful depending upon individual perception.

A new way of reducing anxiety for people having a dental filling or other dental procedures is called sleeping or sedation dentistry. With certain medications, like versed, a person can be in what is called conscious sedation. They will generally not be conscious during the procedure and usually have no memory of it. Dental filling of teeth with conscious sedation is usually more expensive and not covered by insurance.

The easier second half of the dental filling procedure is filling the tooth. Materials for fillings differ. In the US, dental amalgam, and polymer resins are most common. Dental amalgam is made of mercury mixed with metal. Concern about placing mercury into the mouth has been a matter of some debate, since some mercury clearly leeches from the dental filling and is ingested.

This has led some dentists to prefer plastic polymers instead, and some parents to insist on children never receiving a dental filling that contains mercury. As yet, controversy over mercury present in dental amalgam has not subsided. Glass ionomer cements may also be used instead of dental amalgam.

After a dental filling, some people report minor discomfort, once the novocaine wears off. Discomfort may actually derive more from the injection of the novocaine than from the actual dental procedure. Patients may be sent home with instructions for eating soft foods for the remainder of the day, and for avoiding very hot foods while the novocaine remains in effect. By the next day, most people feel no discomfort, and can indulge in any food or drink they like.