It's a sad fact of life that as people age, they will start to have problems with their teeth even if they look after them well. The problem will become much worse if they neglect them. It might be possible to get away with leaving a gap if the lost tooth is from the back of the mouth rather than at the front. In some cases, it will not matter where the lost tooth comes from; you will want it to be replaced. The main two options are:
Depending upon what you want, there are advantages and disadvantages to both of these options.
These have improved greatly over the years and they are by no means the same product that you will remember your grandparents having. They are cheaper to have fitted and are easy to clean as they can come out regularly. Cleaning is easy as there are products that you can buy to do this. They also look very realistic and will make your smile much better. Often there will be a medical reason not to choose implants and choose dentures like when the gums or jaws cannot take implants due to weakness.
When in place, some people find that their dentures rub on the gums and are painful to wear. One downside for dentures is that they could come out when eating as they tend to be held in place with an adhesive. This is annoying when alone, but not something you want to face when you are eating with others. Partial dentures can also be problematic as poorly fitted ones can damage the adjoining teeth and lead to infection.
There are pros and cons as well when it comes to getting implants. Your jaws will have to be strong enough to take the screws that fit them. They are going to look the same as your own teeth, and you will clean them in exactly the same way, so it won't be obvious that you have had implants fitted. Many people find that these are best for replacing one or two teeth, but the cost can become high when there are many that have to be fitted, and as a result, people choose dentures as their preferred option.
Both will require a number of visits to the dentist, so you cannot expect there to be an immediate fix, especially, if the tooth that you want replacing has been lost suddenly. Talk with a dentist about implants or denture services to determine which is right for you.