First maxillary premolar (part 1)
The first maxillary premolar contains two cusps called the buccal and lingual cusps. The lingual cusp is shorter and smaller, and it is slightly displaced to the mesial surface. The highest point of each cusp is called the cusp apex. Therefore, the first maxillary premolar presents with the buccal and lingual cusp apexes.
The buccal surface presents two developmental grooves (depressions) - the mesiobuccal and distobuccal developmental grooves. Sometimes the middle lobe of the buccal cusp has a buccal ridge.
The height of the contour of the first maxillary premolar is as follows:
- Buccal - in the connection between the middle and cervical third;
- Palatal (lingual) - in the middle third;
- Mesial and distal - between middle and occlusal thirds.
The first maxillary premolar is narrower mesiodistally than it is buccolingually, and it has an oval occlusal outline with a very sharp mesiobuccal line angle. From the height of the contour, the buccal outline of this tooth is flatter, but the lingual is more rounded.
A very prominent mesial concavity, also called the mesial developmental depression, is located on the mesial surface. It extends from the height of the contour into the root of the tooth.
The first maxillary premolar can present with one or two roots - buccal and lingual roots.