What does my dentist mean when he says he will fuse my back teeth together?

Q. I grind my teeth and smashed two lower back teeth. I have had dental implants and crowns fitted. 6 months ago. I wear a mouthguard at night. I have experienced some discomfirt over the last few weeks. My dentist wants to make a new guard and has said fusing the upper two back teeth togehter will help. what exactly will he do?,