MODERN DENTAL PRACTICE
Contemporary dental practice would be virtually unrecognizable to the itinerant "tooth-drawers"
of earlier times. Modern dentistry uses a variety of techniques to diagnose problems, remove decay, and repair teeth. Local anesthetics are injected into specific areas of the mouth to block nerve conduction and cause the tissues and teeth in the operative area to become numb. High-speed drills, rotating at speeds of up to 300,000 revolutions per minute, rapidly remove the decayed tooth structure with minimum discomfort. A water spray helps maintain a clear operating field and keeps the nerve inside the tooth from overheating. In 1997 a laser that replaces the drill was approved for use on adults, and in October 1998 for use on children.
Fillings
Silver amalgam, a refinement of filling materials first discovered by the Europeans in the early 1800s, is still widely used. After the components of silver amalgam (silver, tin, mercury) are mixed, the material slowly hardens. During its initial soft stage, it is placed into the cavity produced by the removal of decay. As the amalgam hardens, it is carved to the proper contour to restore the tooth. Newer filling materials made of plastic polymers are becoming more widely used. Once used only in nonstress areas in the front part of the mouth, they are now being utilized in posterior chewing areas. They have an advantage over metal fillings in that the color can be matched to the surrounding tooth and the material can be chemically bonded to tooth structure. Ongoing technological advances improve aesthetic
restoration of teeth infected by
dental decay while maintaining and protecting unaffected areas of the teeth.
Tooth Restoration
Gold and porcelain have been used for restoring tooth structure utilizing "lost wax" techniques of casting. These restorations use a precise set of techniques to prepare the cavity in the tooth, take an impression, and make a plaster of Paris "positive" mold. This mold is used to prepare a second mold constructed of wax. The wax in this mold is replaced by molten restorative material, and the resulting restoration is secured by an adhesive. Computer-assisted technology can now produce gold and ceramic restorations. After the decay is removed from a tooth, a video scanner records the anatomical details of the cavity area. This information is electronically transmitted to a milling machine, which then produces an exact restoration for the cavity.
Tooth Decay
Important changes have occurred in the incidence of dental decay. Several preventive dentistry approaches were initiated in the 1960s. Among the most effective of these was the use of fluoride, through topical application with toothpastes and gels and via-water supply augmentation. The last has been a controversial procedure. Some consumer advocates worry about potential adverse health risks associated with fluoride in water (see fluoridation). Despite the controversy, the use of fluoride soon showed benefits. For example, there was a 50-percent reduction of dental decay in adolescents and young adults during the 1970s and 1980s, and the percentage of children in the United States under age 12 who were decay-free rose from 30 percent to almost 50 percent. The use of dental sealants, plastic material that is poured into the decay-prone grooves in children's teeth, has also helped reduce the incidence of adolescent tooth decay. Special rinses have been found to help small cavities remineralize, instead of treatment by drilling and filling. The decline in decay rate has allowed the dental profession to expand its activities and devote more attention to other aspects of oral health and disease, as well as cosmetic aspects of dentistry, such as tooth whitening.