COVID-19 situation has raised the risk of air-borne diseases in dental offices, while dental clinic and hospitals are facing difficulties hiring dental assistants for many reasons. To solve this problem, a prototype of dental assistant robot that can effectively block aerosols from the patient’s mouth and replace simple tasks of the dental assistants was researched and developed. The ultimate specific goal of the function intended to be implemented was “to enable preparations of lower molar teeth by dentist alone.” Although it was possible to achieve the goal with the first prototype, improvements are needed to improve efficiency and stability. Through continuous improvement and development, dental assistant robots are expected to be of great help to patients, medical assistants, and dentists.