The term “side tooth” commonly refers to the posterior teeth, located toward the back of the mouth behind the canines. These teeth are fundamental to the process of eating and are classified into two main groups: premolars and molars. They work together to prepare food for digestion, and understanding their structure provides insight into the mechanics of the human bite.
Identifying Premolars and Molars
The permanent adult dentition includes premolars and molars, which collectively make up the side teeth. Premolars are positioned directly behind the canine teeth, serving as a transitional set between the sharp front teeth and the grinding teeth in the back. They are sometimes referred to as bicuspids because they typically feature two cusps on their biting surface.
A full set of adult teeth normally contains eight premolars, with two located in each of the four quadrants of the mouth. Situated immediately behind the premolars are the molars, which are the largest and most posterior teeth. A complete adult set includes twelve molars: the first, second, and third molars (commonly known as wisdom teeth). If the third molars are removed or fail to erupt, the total number of molars is reduced to eight, resulting in 28 total teeth.
The Role of Side Teeth in Mastication
The primary purpose of the side teeth is mastication, the process of chewing and grinding food. Premolars function as a bridge, utilizing features of both canines and molars to tear, crush, and break down food into smaller pieces. This initial crushing action prepares the food for the intensive grinding that occurs further back in the mouth.
Molars are primarily responsible for the powerful grinding required to pulverize tougher substances. Their broad, relatively flat chewing surfaces, known as occlusal surfaces, allow them to withstand the significant forces involved in crushing food. About 90% of the total chewing action takes place on the molars, making them the main engine of the digestive process.
Key Anatomical Differences
Premolars and molars have distinct structural differences that reflect their roles in chewing. Premolars, often called bicuspids, most frequently possess two cusps on their chewing surface. In contrast, molars are built for maximum surface area and typically feature four or five cusps. This greater number of cusps provides the molars with a complex surface pattern for efficient grinding.
The internal anchoring structure also varies significantly. Premolars usually have only one root, though the first premolar in the upper jaw often has two roots for added support. Molars generally have multiple roots to provide the stability needed for crushing forces. Mandibular (lower) molars typically have two roots, while maxillary (upper) molars commonly feature three roots. Molars also possess a larger overall crown size and greater occlusal surface area than premolars, enhancing their capacity for pulverizing food.
Primary Versus Permanent Side Teeth
The dentition of a child differs substantially from that of an adult, particularly regarding the side teeth. Primary dentition, often called baby or deciduous teeth, includes molars but does not contain any premolars. Children have a total of eight primary molars, with two in each quadrant of the mouth. These primary molars function similarly to adult molars, providing the necessary chewing surface.
The permanent premolars that erupt later in life replace the primary molars when they are shed, typically between the ages of 10 and 12. The permanent molars are considered non-succedaneous because they erupt into empty space behind the primary teeth. This developmental sequence allows the jaw to lengthen and accommodate the full set of 32 permanent teeth.