Final answer:
To facilitate infection control of dental chairs, chair design should include removable and washable upholstery, smooth and non-porous surfaces, and easy access to all parts for cleaning; hence, the correct answer is 'All of the above'.
Step-by-step explanation:
Infection control of dental chairs is a critical procedure in dental offices to maintain the highest level of hygiene and prevent cross-contamination between patients. Dental chair design plays a significant role in easing the infection control process and should include features such as removable and washable upholstery, which allows for laundering and thorough disinfection, smooth and non-porous surfaces that do not harbor contaminants and are easy to wipe down, and easy access to all parts for cleaning to ensure no areas are missed during the disinfection process. Therefore, the correct answer to which design features should be included to facilitate infection control of dental chairs is 4) All of the above.