According to Butler's Field theory, which tooth type is considered least stable?

In Butler's Field theory, the concept of tooth stability is closely associated with the functionality and positioning of different tooth types within the dental arch. The last tooth in each class, except for lower incisors, is deemed the least stable due to its more distal position in the dental arch, which can lead to various erratic movements over time.

These last teeth—such as the last molars in each quadrant—often lack support from adjacent teeth for stability and can be prone to shifting as other teeth move or are lost. They are also impacted more significantly by forces during chewing and can face additional challenges from surrounding anatomical structures. Additionally, they are at a higher risk of becoming impacted or drifted, contributing to their classification as less stable.

The other tooth types mentioned, such as upper canines and incisors, generally provide better stability due to their central positioning in the dental arch and their interdigitation with opposing teeth, providing a more balanced occlusion. Lower incisors, while they do face some risks due to their position, still have more stability compared to the last teeth in each class, as they are less prone to the same degree of movement and maintain better contact with neighboring teeth.

Thus, the characterization of the last tooth in each class (