Dental restoration

Dental restoration refers to clinical treatments used to restore the function, integrity, and morphology of tooth structure. These procedures address damage caused by dental caries, which is tooth decay, or by physical trauma and wear.

Restorations are also used to seal teeth after root-canal therapy or to protect structures around dental implants. By replacing lost tissue, these treatments allow the tooth to continue working within the complex system of the mouth.

The process begins with tooth preparation to create space for restorative materials. Dentists use a rotary dental handpiece with burrs, dental lasers, or air abrasion to remove decay.

They must also remove unsupported enamel. While enamel is the hardest substance in the human body, it is also very brittle. If enamel lacks underlying support from the dentin, it can fracture easily. The resulting shaped area is called a tooth preparation. This preparation can be intracoronal, meaning it stays within the crown, or extracoronal, providing a base for larger structures like crowns.

Restorations are categorized into two main types: direct and indirect. Direct restorations are placed and shaped during a single dental visit. The dentist puts a malleable material into the prepared cavity, and it sets hard in place.

To ensure the tooth is easy to clean, a dentist might use a matrix. A sectional matrix is often preferred for composite restorations because it helps form a proper contact point between teeth. This prevents food impaction, which is when food gets stuck between teeth.

Indirect restorations are fabricated outside the mouth, often in a dental laboratory. The dentist takes impressions of the prepared tooth to create a model.

A technician then builds the restoration, such as an inlay, onlay, bridge, or veneer. These are later bonded to the tooth using dental cement. This process usually requires two separate appointments. Because they are made externally, indirect restorations like onlays or crowns offer greater durability and structural support.

Humans have been attempting dental repairs for millennia. In Italy, evidence from the Paleolithic period shows bitumen was used as a filler 13,000 years ago. In Neolithic Slovenia, people used beeswax to close tooth fractures 6,500 years ago. Even Graeco-Roman literature, such as Pliny the Elder's writings from the first century AD, mentions materials for hollow teeth. Today, technology has advanced to include the CEREC method. This uses a camera to take an optical impression, which software converts into a 3D virtual model. A milling machine then carves a ceramic restoration from a block in a single visit.

Material choice is critical for the success of the restoration. Amalgam is a common direct material made of an alloy of silver, tin, and copper, with mercury added.

Modern copper-enriched amalgams contain between 12% and 30% copper to improve strength and corrosion resistance. While amalgam is durable and cost-effective, it is silvery-grey and lacks the aesthetic appeal of tooth-colored composites. For more complex needs, casting alloys are used. These include precious metals like high-purity gold or base metals like cobalt-chrome and nickel-chrome. Titanium is also used for implants because it is biocompatible, meaning it can integrate into the bone.

Dentists often use classification systems to decide on a treatment. G.V. Black developed a system to classify cavities based on their location. For example, Class I involves pits and fissures, while Class II affects the proximal surfaces of molars. Another professional, Graham J. Mount, classified cavities by both site and size. This helps clinicians define the complexity of a lesion as it grows. Understanding these classifications ensures the dentist selects the correct material and preparation technique for the specific damage.