Crowns on molars, my teeth keep hitting. What can I do?

I had 6 crowns placed on my back upper and lower molars. Two top right, two bottom right, one top left, one bottom. Now my front teeth are hitting, they never did that before and i chipped two premolars because the premolars are hitting harder than the molars. The dentist wanted to grind down my front bottom teeth and i said no. The dentist keeps cllaiming i have proper occlusionn in the back but im telling you the weight is on the premolars and now my front teeth. What do I do. Help!