To date, Norwich City Council has received 48 objections over a bid to turn Cotman House near the Cathedral into a flat.
Patients fear the conversion will be the “wrong decision” for the “vital community resource” if planners for the council approve the application.
One person said: “Without it, hundreds of children will lose the NHS dental service. I strongly object to this community resource being closed.”
Another person added: “If this dentist and his team has to leave just to increase the Airbnb or other rental income profits of the owner, it will be a serious and wrong decision.
“It will lead to a further reduction in the varied and vibrant services that this fine city can offer.”
Other patients are worried the plans will leave “hundreds” of people in the city without dental care as Norfolk becomes one of the worst so-called “dental deserts” in the UK.
One patient who wrote to the council said: “This change of use will deprive some 1,500 Norwich residents of vital healthcare.
“It will be impossible for this number of patients to find alternative dental care.
“This is an outstanding surgery providing first-rate care to Norwich people and is conveniently located for those without transport.”
The plans – lodged by Dean Shields of Domus Management Ltd – detail the conversion of the dental surgery at St Martin at Palace Plain into a kitchen and dining area.
As part of the proposals, the staff room and the current toilet and decontamination room could also be converted into two bedrooms.
Jonathan Frost, a dentist at the surgery said: “We are very grateful for all the support shown by our patients.
“We have been here for 22 years and are very proud of the Cotman House Dental Surgery.
“We would very much like to continue providing the continuity and quality of care that we are so proud of to our broad patient base.”