Those pursuing perfection are advised to hide their gums, hold back on the bleach, cover the bottom teeth and set their lips at just the right angle.

• 专家建议，那些追求完美笑容的人应该藏起他们的牙肉，不要漂白牙齿，不要露出下排牙齿、嘴唇要保持合适的弧度。