A method for treating a sphincter provides a polymer material having a liquid state. The method also provides a catheter having a distal end, a tissue piercing device carried by the distal end, and an energy delivery device coupled to the tissue piercing device. The tissue piercing device has a lumen. The method introduces the catheter into an esophagus and pierces an exterior sphincter tissue surface within with the tissue piercing device. The method advances the tissue piercing device into an interior sphincter tissue site and conveys the polymer material while in a liquid state through the lumen into the interior sphincter tissue site. The method delivers energy to the tissue piercing device to transform the polymer material into a less liquid state within the interior sphincter tissue site, to thereby remodel the sphincter.