Teeth function to break up food particles by biting and chewing. According to the book, "How the Body Works," teeth stem from specialized hardened regions of the gum tissue, and include the visible crown, composed of dentine covered by enamel, and the root which is embedded within a socket of the jaw bone. Human teeth begin developing in utero, or during pregnancy, and children have a primary set of 20 "milk teeth" until about six years of age. From the second wave of production, humans develop 32 permanent teeth which consist of four different types, each with its own shape and particular function.
Incisors
A total of eight incisors, or two sets of four on the upper and lower jaw, are located in the front and center of the mouth. According to Aetna, the middle pair on the top and bottom are called central incisors, while the teeth on each side of the pair are named lateral incisors. The flat, broad and chisel-like narrow edges of the incisors allow for a "chopping" motion and cutting of food into chewable pieces. HealthyTeeth.org also calls incisors the sharpest teeth designed to move the food inward.
Canines
Humans have four canines, one in each quadrant of the jaw if the layout of teeth were divided into two sections on both the upper and lower jaw. Canine teeth, also known as cuspids, are located on each side of the incisors. These sharp and pointed teeth are anchored in the jaw by a long root which gives the canines stability needed for ripping, tearing and piercing motions. The pointed surface is necessary for consumption of tough foods like meat.
Premolars
Right behind the canine teeth are two premolars on each side of the jaw, for a total of eight premolars. Also known as bicuspids, premolars have cusps on top of broader surfaces that allow for grinding and chewing. According to Aetna, premolars act as a combination of a canine and a molar because in addition to a broad chewing surface, they also include sharp points on the surface for piercing and ripping food.
Molars
After biting off a piece of food with the incisors or the canines, most of the chewing occurs in the back of the jaw by way of the molar teeth. Molars are the largest teeth, and have a flattened surface and several cusps to chew, crush and grind food to the smallest particle possible before swallowing. Humans have three molars in each quadrant of the jaw, with a combined total of 12. Molars receive numbered names according to their location: first molars are adjacent to second premolars towards the back of the mouth, with second and third molars following consecutively. Third molars, often called wisdom teeth, are the last to erupt and sometimes do not come through at all.
References
- "How the Body Works"; Dr. Peter Abrahams; 2007
- Simple Steps to Better Dental Health (Aetna): Types of Teeth
- HealthyTeeth.org: The Different Kinds of Teeth
