Try a new color, or perhaps electric toothbrush. Mouthwash one more essential for the people who aren't able to brush their smiles.
If he refuses to permit you brush his teeth, take him to the veterinarian and let her do it for a. Brush your teeth twice per day, morning and nights. http://mall.goodinvent.com/bbs/board.php?bo_table=free&wr_id=5937