Metals used in dentistry... How safe?

"Every tooth in a man’s head is more valuable than a diamond,” quoted Miguel de Cervantes in his novel Don Quixote, in 1605. The human body is known as a biological machine. Certain parts of the body do not heal naturally and hence need replacement for restoration of function. Teeth and certain organs in the mouth require certain types of metals to help them continue their function. Metals in the form of titanium screws, as replacements for missing teeth, have been found to be employed by the Mayan civilization since around 600 AD, i.e. 1350 years before modern civilizations began working with titanium. Use of metal fillings to fill teeth began in the early 19th century, with gold being the first metal used in dental works. Various semi-precious and base metals such as silver-palladium, palladium-copper, silver-gold-copper, chromium-cobalt, and nickel-chromium alloys are casted as base metals for ceramic caps, bridges, denture bases and prosthesis in dentistry. Nowadays, titanium alloys are widely utilized in dental implants and other prostheses. Accordingly, with this integration of metals, the human body can be seen as a bio-mechanical apparatus. The purpose of metal use in dentistry varies with the physical and chemical properties of the metal. Lead was also used as a filling material but was abandoned in the late 19th century because of its harmful effects. In some cultures, gold caps and teeth are worn purely as a sign of wealth. Gold used in dentistry should not be confused with its pure 24K form. It is molded into an alloy composed of seventy percent gold, with other metals and fillers in small quantities for modifying color and strength, and is known as Dental Gold. Different aspects of dentistry use dental gold for crowns, bridges, fillings and dentures due to its malleable, ductile and biocompatible properties. Amalgam fillings, commonly called silver fillings, are the most sought after and thoroughly researched materials in dentistry. Claudia Wallis, Associate Dean at Columbia University, said that, “Tooth decay was a perennial national problem that meant a mouthful of silver for patients and for dentists a pocketful of gold,” in spite of the fact that silver fillings are relatively economical. These fillings are made by mixing equal parts liquid mercury and powered metal use of twenty to thirty percent silver, according to the US Food and Drug Administration. The remainder of the alloy is comprised of tin, copper, zinc and other metals. They are valued filling materials due to their durability, resistance to corrosion, fracture-proof qualities and high strength. Scientists have been debating on the use of mercury in dental fillings since 1890. “How is it that mercury is not safe for food additives and over-the-counter drug products, but it is safe in dental amalgams?” It was conclusively admitted by the American Dental Association in 1980 that very small amounts of mercury slowly ooze out of the fillings during chewing, as a result of the interaction of metals with acid and enzymes produced by saliva at 37 degrees centigrade in the oral environment. The fumes are inhaled and reach the brain through the nose. Mercury has also been declared to be an active neurotoxin and has high affinity for nerve tissues. It circulates in the blood stream and cannot be excreted from the body. On the other hand, major US and international scientific and health bodies, including the World Health Organization, among others, are satisfied that dental amalgam is a safe, reliable and effective restorative material. Experts say that mercury is used as an alloy; hence its harmful effects are minimal. Amalgam can withstand high chewing loads and thus is preferred as the material of choice for high-stress-bearing teeth like molars in the back of the mouth. It has also been asserted biocompatible with the body, with allergic responses being quite rare. The use of nickel as nickel-titanium alloy, or Ni-Ti, is extensive in various dental applications such as tooth caps, bridges, dentures, and orthodontic appliances like braces and root-canal instruments. Nickel has been claimed as an allergen for allergic contact dermatitis inside the mouth to clinicians and technicians in general population. However, there is no documented evidence that individual patients are at a significant risk of developing sensitivity solely due to contact with nickel-containing appliances and restorations. Some nickel compounds are mildly toxic to body cells and have been implicated as cancer-causing agents by inhalation in industrial settings, but these compounds are not present in dentistry-related operations, including technical procedures. Hence, it was concluded that nickel-containing alloys do not pose a risk to patients or members of the dental team. Historically, titanium has been expansively used in aerospace, as well as aeronautical and marine applications. Titanium can osseointegrate, i.e. bind with the surrounding body structures at microscopic levels. It has been stated to be highly biocompatible with the human body and corrosion-resistant. It has been sought out as a suitable material for caps, bridges, denture frameworks, prostheses and dental implants, in particular. A dentist is not a prestidigitator who puts metal into your mouth to pull coins out of your pocket. The dentist intends no harm to his patients. His goal is to provide comprehensive and beneficial treatment to patients to improve their health and happiness. He is certainly not responsible for the ill effects of the materials used in dental procedures. The responsibility is solely on each individual to help themselves.