Hello Mary, Thank you for your question and your concern.  It is actually quite a common occurrence,  I am assuming from your question, that the remaining lower teeth you have are your anterior or front teeth. When you are sleeping, you probably are not wearing your complete upper and partial lower dentures, and when we sleep, the muscles involved in the movement of our lower jaw move it up into it’s natural closed position as when we eat and chew our food, so your lower front teeth move up and rest or even bite into the front par of your upper jaw. This is a natural movement, but an uncomfortable one in situations such as yours. As much as I disagree with patients wearing their denture while they sleep, as it is very important and healthy to remove your denture when you go to sleep, in your case keeping them in while you sleep to keep your jaws apart may work, but you should remove them at some time during the day for several hours to relieve pressures on your gums, and to give your mouth the healing time it needs. Also. There should be enough ‘Free way space’ between the front of your lower natural teeth and the back of your upper denture teeth, so when you sleep with your dentures in, there won’t be excessive pressure on your upper ridge and gums, as well as excessive pressure on the anterior part of your lower natural teeth. Your question is a perfect example of how pressure and where it is applied in the mouth can be the difference between a comfortable set of dentures and a good night sleep or constant discomfort. I suggest you discuss this with your dental practitioner where you received your dentures from, or a dentist that has experience in the correct placement and maintenance of dentures. Please let me know if this work, Thank you,