Location, Function, and Anatomy - Mandibular second premolar is located distally from both mandibular first premolars and mesial from both mandibular first molars. - Its function is to assist the mandibular first molar during chewing or mastication. - Mandibular second premolars have three cusps, with one large cusp on the buccal side. - The lingual cusps are well developed and functional. - The mandibular second premolar is more similar to the first molar than the first premolar. - The mandibular second premolar commonly has three cusps but can have two as well. - The occlusal table is rectangular, and the groove pattern is shaped like a Y. - The contacts with adjacent teeth are positioned buccal to the midpoint. - The buccal cusp tip is centered mesiodistally when viewed from the buccal. - The root is generally straight with slight curvature to the distal in the apical third. - The buccal height of contour is in the gingival third of the tooth when viewed from the mesial or distal. - The lingual height of contour is in the middle third of the tooth. - The buccal cusp is at the contact between the buccal and middle thirds when divided into thirds. - 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.

Terminology and Notation - Premolars are sometimes referred to as bicuspids, but the mandibular second premolar has three functional cusps. - The universal system of notation designates the right mandibular second premolar as 29 and the left one as 20. - In the Palmer notation, both right and left second premolars have the number 5, but the right one has the symbol ┐ and the left one has ┌. - The international notation designates the right mandibular second premolar as 45 and the left one as 35.

Congenital Absence - It is common for patients in orthodontics to have one or both mandibular second premolars congenitally absent. - Congenital absence refers to the condition where the premolars do not develop. - This absence can impact the dental alignment and treatment plan. - Orthodontists need to consider the absence of mandibular second premolars when creating treatment strategies. - Alternative options such as space closure or prosthetic replacements may be considered.