Dental material

Examples include: Dental cements are used most often to bond indirect restorations such as crowns to the natural tooth surface.

Examples include: Dental impressions are negative imprints of teeth and oral soft tissues from which a positive representation can be cast.

They are used in prosthodontics (to make dentures), orthodontics, restorative dentistry, dental implantology and oral and maxillofacial surgery.

Impression materials are designed to be liquid or semi-solid when first mixed, then set hard in a few minutes, leaving imprints of oral structures.

A common technique to overcome this issue is to apply a thin sub-lining of calcium hydroxide, then build up with zinc phosphate prior to amalgam condensation.

This generates a relatively high pH environment around the area surrounding the cement due to calcium hydroxide leaking out, thus making it bactericidal.

However, due to its low compressive strength it is unable to withstand amalgam packing; a strong cement base material should be placed above it to counter this.

However, it tends to be rubbery during its setting reaction and adheres to stainless steel instruments, so most operators prefer not to use it in deep cavities.

GI lining contains glass of smaller particle sizes compared to its adhesive restorative mix, to allow formation of a thinner film.

[3] Zinc oxide eugenol is usually used as a temporary filling/luting agent due to its low compressive strength making it easily removed, or as a lining for amalgam as it is incompatible with composites resins.

The majority of clinical studies indicate the annual failure rates (AFRs) are between 1% and 3% with tooth colored fillings on back teeth.

[16] Amalgam does not adhere to tooth structure without the aid of cements or use of techniques which lock in the filling, using the same principles as a dovetail joint.

Bis-GMA based resins contain Bisphenol A, a known endocrine disrupter chemical, and may contribute to the development of breast cancer.

Composite resins experience a very small amount of shrinkage upon curing, causing the material to pull away from the walls of the cavity preparation.

In some circumstances, using composite resin allows less of the tooth structure to be removed compared to other dental materials such as amalgam and indirect methods of restoration.

Clinically, this material was initially used as a biomaterial to replace the lost osseous tissues in the human body.

An advantage of GICs compared to other restorative materials is that they can be placed in cavities without any need for bonding agents.

As GICs release their fluoride, they can be "recharged" by the use of fluoride-containing toothpaste; this means they can be used to treat patients at high risk of caries.

Newer formulations that contain light-cured resins can achieve a greater aesthetic result, but do not release fluoride as well as conventional GICs.

These materials release chemical agents in the form of dissolved ions or growth factors such as bone morphogenetic protein, which stimulates activate cells.

It holds up better than GIC, but not as well as composite resin, and is not recommended for biting surfaces of adult teeth,[22] or when control of moisture cannot be achieved.

Their other advantages are that they adhere directly to tooth tissue, and are radio-opaque, which helps with identification of secondary caries when future radiographs are taken.

Their hardness and rigidity enables them to resist abrasion forces, and are good aesthetically as they mimic the appearance of natural teeth.

[27] Nano-ceramic particles embedded in a resin matrix are less brittle and therefore less likely to crack, or chip, than all-ceramic indirect fillings.

However, recent advances in dental porcelains and a consumer focus on aesthetic results have caused the demand for gold fillings to drop.

According to American Civil War-era dental handbooks, since the early 19th century metallic fillings had been made of lead, gold, tin, platinum, silver, aluminum, or amalgam.

A pellet was rolled slightly larger than the cavity, condensed into place with instruments, then shaped and polished in the patient's mouth.

They were made of: Acrylics are used in the fabrication of dentures, artificial teeth, impression trays, maxillofacial / orthodontic appliances and temporary (provisional) restorations.

They cannot be used as tooth filling materials because they can lead to pulpitis and periodontitis, as they may generate heat and acids during setting, and in addition they shrink.

[29] How well people keep their teeth clean and avoid cavities is probably a more important factor than the material chosen for the restoration.