The bridge itself will not decay, which leads a lot of people to relax about cleaning it. What can fail is the tissue and bone around the implants holding it up, and that is driven almost entirely by what accumulates underneath the bridge where you cannot see.
The daily routine
- Brush the bridge twice a day with a soft brush, including the gum side
- Use a water flosser along the whole underside of the bridge, angled up into the gap
- Thread superfloss under the bridge once a day and work it along the full span
- Use an interdental brush around each implant abutment where there is room
Why the water flosser matters most
A brush cannot reach under a fixed bridge. A water flosser can, and it is the only tool most patients will actually use every day. If you buy one thing after All-on-4 treatment, buy that.
Professional maintenance
Plan on a professional clean every six months, and expect that the bridge will be removed periodically for a thorough clean and inspection underneath. That is routine maintenance, not a problem.
Smoking is the largest single risk factor for implant failure. If you are going to make one change around full-arch treatment, that is the one.