The present invention relates a printhead for an inkjet printer. The printhead has a plurality of nozzle arrangements, with each arrangement having a substrate defining an ink inlet channel leading to a nozzle chamber in fluid communication with the ink inlet channel and an ink ejection port through which ink from the nozzle chamber is ejected. Each arrangement also includes an ink ejection paddle extending across the nozzle chamber between the ink inlet channel and the ink ejection port, and a thermal bend actuator configured to operatively actuate the paddle. Also included is a sealing structure interposed between a working end of the actuator arm and a proximal end portion of the paddle.