If a new filling is placed and it changes the way the teeth articulate or come together it can trigger TMJ symptoms, especially in patients who clench or grind their teeth.
The best way to support TMJ and clenching is to avoid any stimulants such as caffeine, relax the muscles and joint with rest and warm compresses and use a soft mandibular orthotic professionally fabricated and checked for proper occlusion and jaw/joint position.

Seth Black