Toothbrush and Toothpaste

The earliest toothbrushes were simply small sticks mashed at one end to increase their cleaning surface. Ancient Roman aristocrats employed special slaves to clean their teeth.

Tooth Extraction Devices

In primitive societies teeth were extracted with a chisel-shaped piece of wood held against the tooth and pounded with a mallet. Early Chinese tooth-pullers used their fingers.


A tracheotomy is a potentially life-saving surgical procedure. During a tracheotomy, an opening is made in a patient's windpipe to relieve airway obstruction.


Tranquilizers are substances that produce a state of calmness in agitated people. Minor tranquilizers—such as barbiturates—are used in the treatment of anxiety (fearfulness).

Transplant, Surgical

Stories of transplanted tissue and body parts go far back in myth and legend. It is said that in the sixth century, the Christian patron saints of medicine, Cosmos and Damian, performed a transplant.

Tuberculin Test

Tuberculin tests are administered to patients for the diagnosis of tuberculosis (TB). Tuberculosis is a serious bacterial disease that attacks the lungs.

Ultrasound Devices

Before the development of ultrasound devices, there was no way to safely diagnose the condition of a fetus (name given to unborn young from the end of the eighth week of development through birth). Prenatal surgery was extremely risky for both the mother and the unborn child.

Ultraviolet Radiation

Just like visible light, infrared light, and radio waves, ultraviolet light is electromagnetic radiation. Ultraviolet light lies on the spectrum between violet light and X-rays.


Vitamins are organic compounds (mixtures made from living organisms like plant and animal tissue). They are generally divided into two groups: fat-soluble and water-soluble.

Vitamin A

Since its discovery in the early part of the 20th century, researchers have learned a great deal Assorted vitamin pills. Only tiny amounts of each of the 3 vitamins are needed to ensure metabolism, but these minimum amounts are absolutely essential.

Vitamin B12

Vitamin B12 was discovered simultaneously by two research teams, one in the United States and one in England. It was the culmination of an intensive worldwide search for a compound that could effectively treat pernicious anemia.

Vitamin C

Unlike other water-soluble vitamins, vitamin C (ascorbic acid), does not appear to act either as a catalyst or as a coenzyme. Instead, it plays a major role by regulating the formation of collagen.

Vitamin D

Vitamin D is one of the four fat-soluble vitamins. It is concerned with efficient calcium and phosphorus absorption.

Vitamin E

Vitamin E was discovered in 1922 by Herbert M. Evans and K.

Vitamin K

Vitamin K promotes the formation of prothrombin and other blood-clotting proteins in the liver. A deficiency in the vitamin leads both to a slow-down in the clotting process and the strong possibility of a hemorrhage (excessive bleeding).


X-rays are electromagnetic waves, like light waves, but with a wavelength about 1,000 times smaller. Because of this very short wavelength, X-rays can easily penetrate low-density material, such as flesh.

X-ray Crystallography

X-ray crystallography was first developed as a means of determining the nature of X-rays themselves. It was not intended to be a research tool.

X-ray Machine

The first X-ray device was discovered accidentally by the German scientist Wilhelm Roentgen (1845-1923) in 1895. He found that a cathode-ray tube emitted invisible rays that could penetrate paper and wood.

Zygote Intrafallopian Transfer

Zygote intrafallopian transfer (ZIFT) is a variation on a procedure called in vitro fertilization. With in vitro fertilization, an egg is fertilized in the laboratory in a glass petri dish.