Ideal Number of Dental Implants

Philip, a dental implant patient, asks us:

I am a 49-year-old male from the UK and suffering from advanced gum
disease.
I have a few teeth left but they are extremely mobile and they will
have to be extracted.

As far as I am concerned, I want a full set of dental implants for both jaws, as
dentures fill me with absolute dread.
I cannot afford UK prices so I have researched abroad and settled on
Hungary as the best balance between quality and price.
I have sent panoramic X-rays to various dentists in that country and
have had differing opinions on treatment options available to me.

What is clear is that due to extensive bone loss I will definitely need
two sinus lifts before dental implants can be placed.
What I can’t understand is the different number of implants advocated
by different dentists.

Is there an ideal number of dental implants for a complete functioning set of teeth on
both jaws?
The number of dental implants suggested range from four or five on each jaw, to eight and ten being the most suggested. So, I would be very appreciative of your thoughts as to what
constitutes a minimum, or or better yet an ideal number of dental implants? Thanks for your help.