Mandibular second premolar
Encyclopedia
The mandibular second premolar is the tooth
located distally (away from the midline of the face
) from both the mandibular first premolar
s of the mouth
but mesial (toward the midline of the face) from both mandibular first molar
s. The function of this premolar
is assist the mandibular first molar during mastication
, commonly known as chewing. Mandibular second premolars have three cusp
s. There is one large cusp on the buccal side (closest to the cheek) of the tooth. The lingual cusps (located nearer the tongue) are well developed and functional (which refers to cusps assisting during chewing). Therefore, whereas the mandibular first premolar resembles a small canine, the mandibular second premolar is more alike to the first molar. There are no deciduous
(baby) mandibular premolars. Instead, the teeth that precede the permanent
mandibular premolars are the deciduous mandibular molars.
Anatomy: The mandibular second premolar most commonly has three cusps but can have two as well. The three cusp variety has one large cusp on the buccal with two smaller lingual cusps. The mesiolingual cusp is twice the size of the disolingual cusp. Viewed from the occlusal (looking down onto the biting surface of the tooth) the tooth is rather square in outline, particularly on the lingual. The occlusal table (the area bounded by the cusps, cusp ridges, and marginal ridges) is rectangular. The groove pattern is shaped like a “Y” with the tail pointed to the lingual and placed between the distolingual and mesiolingual cusps one third of the distance form the distal to the mesial. The contacts with the adjacent teeth are positioned buccal to the midpoint. Viewed from the buccal the buccal cusp tip is centered mesiodistally. The buccal cusp ridges exhibit slight concavities that extend over the buccal surfaces as developmental grooves into the gingival embrasure. The contacts with adjacent teeth are in the occlusal third of the tooth with the distal height of contour slightly closer to the gingival than the mesial height of contour. The root is generally straight with slight curvature to the distal in the apical third. Viewed from the mesial or distal the buccal height of contour is in the gingival third of the tooth. The lingual height of contour is in the middle third of the tooth (not the middle third of the lingual cusp). When divided into thirds from the buccal height of contour to the lingual height of contour, the buccal cusp is at the contact between the buccal and middle thirds and the central groove is at the contact of the middle and lingual thirds. The two cusp variety generally has a groove pattern shaped like a “U” or “H”. Viewed from the occlusal it is more rounded in general and its lingual cusp is positioned slightly to the mesial, while the occlusal table remains squared. Viewed from the buccal the buccal cusp is centered over the root as in the three cusp variety. Viewed from the mesial or distal its heights of contour are similar to the three cusp variety.
Sometimes, premolars are referred to as bicuspids. Even though the terms are synonymous, "bicuspid" refers to having two functional cusps, and the mandibular second premolar is an example of a premolar with three functional cusps. Thus, "biscupid" is technically not as accurate as "premolar".
In the universal system of notation
, the permanent mandibular premolars are designated by a number. The right permanent mandibular second premolar is known as "29", and the left one is known as "20". In the Palmer notation
, 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 premolars would have the same number, "5", but the right one would have the symbol, "┐", over it, while the left one would have, "┌". The international notation has a different numbering system than the previous two, and the right permanent mandibular second premolar is known as "45", and the left one is known as "35".
It is a very common condition in orthodontics for a patient to have one or both mandibular second premolars congenitally absent.
Tooth
Teeth are small, calcified, whitish structures found in the jaws of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are...
located distally (away from the midline of the face
Face
The face is a central sense organ complex, for those animals that have one, normally on the ventral surface of the head, and can, depending on the definition in the human case, include the hair, forehead, eyebrow, eyelashes, eyes, nose, ears, cheeks, mouth, lips, philtrum, temple, teeth, skin, and...
) from both the mandibular first premolar
Mandibular first premolar
The mandibular first premolar is the tooth located laterally from both the mandibular canines of the mouth but mesial from both mandibular second premolars. The function of this premolar is similar to that of canines in regard to tearing being the principal action during mastication, commonly...
s of the mouth
Mouth
The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....
but mesial (toward the midline of the face) from both mandibular first molar
Mandibular first molar
The mandibular first molar or six-year molar is the tooth located distally from both the mandibular second premolars of the mouth but mesial from both mandibular second molars...
s. The function of this premolar
Premolar
The premolar teeth or bicuspids are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered as a 'transitional tooth' during chewing, or...
is assist the mandibular first molar during mastication
Mastication
Mastication or chewing 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 more efficient break down by enzymes. During the mastication process, the food is positioned between the teeth for grinding by...
, commonly known as chewing. Mandibular second premolars have three cusp
Cusp (dentistry)
A cusp is an occlusal or incisal eminence on a tooth.Canine teeth, otherwise known as cuspids, each possess a single cusp, while premolars, otherwise known as bicuspids, possess two each. Molars normally possess either four or five cusps...
s. There is one large cusp on the buccal side (closest to the cheek) of the tooth. The lingual cusps (located nearer the tongue) are well developed and functional (which refers to cusps assisting during chewing). Therefore, whereas the mandibular first premolar resembles a small canine, the mandibular second premolar is more alike to the first molar. There are no deciduous
Deciduous teeth
Deciduous teeth, otherwise known as reborner teeth, baby teeth, temporary teeth and primary teeth, are the first set of teeth in the growth development of humans and many other mammals. In some Asian countries they are referred to as fall teeth as they will eventually fall out, while in almost all...
(baby) mandibular premolars. Instead, the teeth that precede the permanent
Permanent teeth
Permanent teeth are the second set of teeth formed in humans. There are thirty-two permanent teeth, consisting of six maxillary and six mandibular molars, four maxillary and four mandibular premolars, two maxillary and two mandibular canines, four maxillary and four mandibular incisors.The first...
mandibular premolars are the deciduous mandibular molars.
Anatomy: The mandibular second premolar most commonly has three cusps but can have two as well. The three cusp variety has one large cusp on the buccal with two smaller lingual cusps. The mesiolingual cusp is twice the size of the disolingual cusp. Viewed from the occlusal (looking down onto the biting surface of the tooth) the tooth is rather square in outline, particularly on the lingual. The occlusal table (the area bounded by the cusps, cusp ridges, and marginal ridges) is rectangular. The groove pattern is shaped like a “Y” with the tail pointed to the lingual and placed between the distolingual and mesiolingual cusps one third of the distance form the distal to the mesial. The contacts with the adjacent teeth are positioned buccal to the midpoint. Viewed from the buccal the buccal cusp tip is centered mesiodistally. The buccal cusp ridges exhibit slight concavities that extend over the buccal surfaces as developmental grooves into the gingival embrasure. The contacts with adjacent teeth are in the occlusal third of the tooth with the distal height of contour slightly closer to the gingival than the mesial height of contour. The root is generally straight with slight curvature to the distal in the apical third. Viewed from the mesial or distal the buccal height of contour is in the gingival third of the tooth. The lingual height of contour is in the middle third of the tooth (not the middle third of the lingual cusp). When divided into thirds from the buccal height of contour to the lingual height of contour, the buccal cusp is at the contact between the buccal and middle thirds and the central groove is at the contact of the middle and lingual thirds. The two cusp variety generally has a groove pattern shaped like a “U” or “H”. Viewed from the occlusal it is more rounded in general and its lingual cusp is positioned slightly to the mesial, while the occlusal table remains squared. Viewed from the buccal the buccal cusp is centered over the root as in the three cusp variety. Viewed from the mesial or distal its heights of contour are similar to the three cusp variety.
Sometimes, premolars are referred to as bicuspids. Even though the terms are synonymous, "bicuspid" refers to having two functional cusps, and the mandibular second premolar is an example of a premolar with three functional cusps. Thus, "biscupid" is technically not as accurate as "premolar".
In the universal system of notation
Universal numbering system (dental)
The Universal numbering system is a dental notation system for associating information to a specific tooth, and is commonly used in the United States.The designations "left" and "right" on the chart correspond to the patient's left and right, respectively....
, the permanent mandibular premolars are designated by a number. The right permanent mandibular second premolar is known as "29", and the left one is known as "20". In the Palmer notation
Palmer notation
Palmer notation is a system used by dentists to associate information to a specific tooth. Although supposedly superseded by the FDI World Dental Federation notation, it overwhelmingly continues to be the preferred method used by orthodontists, dental students and practitioners in the United...
, 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 premolars would have the same number, "5", but the right one would have the symbol, "┐", over it, while the left one would have, "┌". The international notation has a different numbering system than the previous two, and the right permanent mandibular second premolar is known as "45", and the left one is known as "35".
It is a very common condition in orthodontics for a patient to have one or both mandibular second premolars congenitally absent.