When you have metal dental work in your mouth, one possibility is that you can have an allergy to that metal. This can cause a variety of symptoms, one of which would be chronic inflammation around that dental work.
The metal most often implicated in metal allergies is nickel, although there are other components in dental metals that can provoke sensitivity. Beryllium, chromium, and nickel are the three that have that potential. Cobalt has also been implicated as a potential allergen. Other metals that are used in dentistry—including gold, platinum, silver, palladium, tin, zinc, titanium—are hypoallergenic.
One reason that dentists use alloys with nickel in them is that these alloys are considerably less expensive. There are three basic categories of metal alloys used in dental crowns. The most expensive is called high noble. A dental alloy of this class must have at least 60% noble metal, and the noble metals are gold, platinum, and palladium. Other metals that may be present in these alloys could include silver, copper, zinc. The next most expensive is called noble alloy, which must have at least 25% noble metal. The cheapest is called base metal. Base metal alloys used in dentistry will usually have nickel and chromium in them, and possibly also cobalt.
Many people are allergic to nickel. The Centers for Disease Control estimates that 10-20% of the population are allergic to nickel. Often the allergy becomes noticeable with earrings and people with metal allergies will need to get non-allergenic earrings, made without nickel.
Nickel, besides being a component of base metal alloys used for dental crowns, is also used in removable partial dentures. If you have a sensitivity to nickel, you will experience a chronic inflammation around these crowns or partials.
Nickel is also present in some dental posts or dental pins that are used in teeth with root canal treatments, to help strengthen the tooth and retain a dental crown. Most metal posts these days are made out of titanium, which is a very bio-compatible element, but posts with nickel in them are still available. Some may argue that a post inside a tooth will not provoke any allergic reaction, but the tooth root is porous, and recent studies have shown that molecules of corrosion products of metals inside the tooth can easily seep through the tooth, given enough time.
Allergy to dental amalgam, an alloy of silver, mercury, and small amounts of tin, copper, and/or zinc, is very rare, but instances have been reported. I am not aware of any documented allergies to precious metals such as gold and platinum.
Based on email questions I get from patients, many dentists ignore this metal allergy issue. In my opinion, every dentist should have a medical history questionnaire in which they ask patients if they have ever had a sensitivity reaction to any metal, and, if they have, their chart should be flagged to avoid any of these base metals such as nickel and chromium.