Implant Supported Fixed Bridge: How Difficult Is This to Maintain?

I currently have a full upper denture which I have had for several years. I hate the way the denture feels and want to have it replaced with dental implants. Ideally, I would like to get what I believe is called a fixed bridge – meaning an implant attached porcelain over metal appliance that is non-removable (at least not removable by me).Because I have been missing a significant number of upper teeth for quite some time, my dentist tells me that there may not be sufficient bone mass for this type of implant fixed bridge. So my dentist recommends is a removable overdenture. Evidently, the removable overdenture doesn’t require as many implants, so bone mass isn’t as much of a problem.However, if my CAT scan shows sufficient bone mass for a non-removable upper fixed bridge I am really inclined to go with that option. However, my dentist told me that a downside to a non-removable fixed bridge is that it accumulates food and bacteria between the bridge and the gum, is difficult to keep clean, and can lead to dental infections.Is this true? Are dental infections common with non-removable implant supported fixed bridges? Are they that difficult to keep clean? All things considered, if I have enough bone is the non-removable fixed bridge a better consideration for me? Is it more comfortable than an overdenture?