The mandibular second molar is the

tooth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, ...

located distally (away from the midline of the

face The face is the front of an animal's head that features the eyes, nose and mouth, and through which animals express many of their emotions. The face is crucial for human identity, and damage such as scarring or developmental deformities may aff ...

) from both the mandibular first molars of the

mouth In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on ...

but mesial (toward the midline of the face) from both mandibular third molars. This is true only in

permanent teeth Permanent teeth or adult teeth are the second set of teeth formed in diphyodont mammals. In humans and old world simians, there are thirty-two permanent teeth, consisting of six maxillary and six mandibular molars, four maxillary and four mand ...

. The function of this molar is similar to that of all molars in regard to grinding being the principal action during

mastication Chewing or mastication is the process by which food is crushed and ground by teeth. It is the first step of digestion, and it increases the surface area of foods to allow a more efficient break down by enzymes. During the mastication process, ...

, commonly known as chewing. Though there is more variation between individuals than that of the first mandibular molar, there are usually four

cusp A cusp is the most pointed end of a curve. It often refers to cusp (anatomy), a pointed structure on a tooth. Cusp or CUSP may also refer to: Mathematics * Cusp (singularity), a singular point of a curve * Cusp catastrophe, a branch of bifurc ...

s on mandibular second molars: two on the buccal (side nearest the cheek) and two lingual (side nearest the

tongue The tongue is a muscular organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive process, and is the primary organ of taste. The tongue's upper surface (dorsum) is covered by taste ...

). There are great differences between the

deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, ...

(baby) mandibular molars and those of the permanent mandibular molars, even though their function is similar. The permanent mandibular molars are not considered to have any teeth that precede them. Despite being named molars, the deciduous molars are followed by permanent premolars. In the universal system of notation, the deciduous mandibular second molars are designated by a letter written in uppercase. The right deciduous mandibular second molar is known as "T", and the left one is known as "K". The international notation has a different system of notation. Thus, the right deciduous mandibular second molar is known as "85", and the left one is known as "75". In the universal system of notation, the permanent mandibular second molars are designated by a number. The right permanent mandibular second molar is known as "31", and the left one is known as "18". In the

Palmer notation Palmer notation (sometimes called the "Military System" and named for 19th-century American dentist Dr. Corydon Palmer from Warren, Ohio) is a dental notation (tooth numbering system). Despite the adoption of the FDI World Dental Federation not ...

, a number is used in conjunction with a symbol designating in which quadrant the tooth is found. For this tooth, the left and right second molars would have the same number, "7", but the right one would have the symbol, "┐", underneath it, while the left one would have, "┌". The international notation has a different numbering system from the previous two, and the right permanent mandibular second molar is known as "47", and the left one is known as "37". An eighth cusp was found in a primary second lower molar in an Argentinean child.

References

*Ash, Major M. and Stanley J. Nelson, 2003. ''Wheeler’s Dental Anatomy, Physiology, and Occlusion.'' 8th edition. *Rodriguez-Florez, C.D. et al., 2006. Occurrence of an Eighth Cusp on Primary Second Mandibular Molars of a Contemporary Argentinean Child. Dental Anthropol 19(3): 83-85. (http://anthropology.osu.edu/DAA/back%20issues/DA%20Vol%2019%203.pdf) {{Tooth anatomy Types of teeth Human mouth anatomy