Worn brake pads damage the brake disc and caliper.
2006 FordF 250 Super duty Customer complaint grinding noise brake pedal goes to floor. We inspected and found the right rear wheel soaked with brake fluid . When we jacked up the vehicle and removed the wheel we found that the caliper sliding pins had frozen. which would not release the brake pad and caused the pad to wear and resulted in the caliper piston damage. The ford F250 has plastic pistons.