The 'mandibular second premolar' is the
tooth located distally (away from the midline of the
face) from both the
mandibular first premolars of the
mouth but mesial (toward the midline of the face) from both
mandibular first molars. The function of this
premolar is assist the mandibular first molar during
mastication, commonly known as chewing. Mandibular second premolars have three
cusps. 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.
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".
References
★ Ash, Major M. and Stanley J. Nelson, 2003. ''Wheeler’s Dental Anatomy, Physiology, and Occlusion.'' 8th edition.