Maxillary first premolars

• Generally, premolars are bicuspids with one large buccal cusp and a smaller lingual cusp
• The maxillary first premolar has two roots and two prominent cusps
• The buccal cusp is significantly larger (by 1mm) than the lingual cusp
• There is a prominent buccal ridge and cervical ridge, and two small depressions on either side of the buccal ridge (common in all premolars)
• The facial outline is pentagonal
• The tip of the buccal cusp lies mesial to the midline of the root
• The lingual surface is narrower than the buccal (buccolingual convergence)
• The distal slope of the lingual cusp is longer than the mesial slope
• Proximally, the crown as a trapezoid shape
• Occlusally the outline is polygonal
• The maxillary first premolars are more symmetrical with equal mesiobuccal and distobuccal sides
• The mesial side is shorter than the distal side
• The mesiolingual side is shorter than the distolingual side
• The buccolingual dimension is greater than the mesiodistal dimension
• The occlusal surface has buccal and lingual triangular ridges, and mesial and distal marginal ridges
• Occlusally there is a central developmental groove as well as mesial and distal triangular fossae next to the triangular ridges
• One of the most prominent features is the mesial marginal developmental groove
• The maxillary first premolar has a canine fossa mesially to accommodate for the bulge of the maxillary canne
• The mesial cusp ridge is longer than the distal one