Dentures can be an excellent way of providing extra teeth relatively quickly, but do take some getting used to, both in terms of speech and eating.
Patients tend to adapt within 1 month, and then find that comfort levels are such that they can continue as they are until they are in a position to consider longer term solutions like dental implants or bridges if viable.
If bridges and implants are not suitable, the denture itself, could be a longer-term option, assuming that the remaining teeth and gums are healthy and stable. This would be assessed at the treatment planning stages and the type of denture construction would be made on that basis.
Dentures can also be stabilised or fixed by connecting them to dental implants. This is a more advanced technique and would need significant amount of due diligence, but is the most secure way of securing dentures and stop them from moving around.