Which position should the patient chair be adjusted in order to work on the mandibular arch?

The most appropriate position for the patient chair when working on the mandibular arch is the back of the chair raised 25 to 45° from the floor. This positioning allows for optimal visibility and access to the lower teeth, which are situated in the mandibular arch.

By reclining the chair to this angle, the dental professional can achieve a comfortable stance and work efficiently without straining their back or obstructing their view. This angle also helps reflect light properly into the oral cavity, enabling better examination and treatment.

In contrast, a flat horizontal position would place the patient at an angle that is too low for effective access to the mandibular arch, making it difficult for the dental assistant or dentist to perform procedures effectively. Raising the back of the chair to 60 to 90° would position the patient too upright, which can also hinder both visibility and accessibility. Lowering the back of the chair by 10 to 20° would be inadequate as it does not provide the necessary angle to work comfortably and efficiently on the mandibular arch.