Which factor is least likely to contribute to post-operative sensitivity in dental procedures?

Post-operative sensitivity in dental procedures can arise from various factors, but the likelihood of each factor contributing to this sensitivity can vary. When considering infection as a potential contributor, it's important to understand that while infections can cause discomfort and sensitivity, they typically manifest in scenarios where there's already underlying tissue damage, such as decay or periodontal issues.

In contrast, mechanical trauma from preparation, allergic reactions to materials, and chemical irritation directly relate to the procedures performed and the materials used. Mechanical trauma can lead to immediate sensitivity from the drilling or cutting of teeth, while allergic reactions and chemical irritation may provoke inflammatory responses in the dental pulp or surrounding tissues, leading to sensitivity following treatment.

Infection, although concerning, is generally a late consequence that may occur after initial sensitivity has already been presented due to specific mechanical, chemical, or material reactions during the procedure. Therefore, it is considered the least likely factor contributing to post-operative sensitivity when comparing it to the other more immediate factors.