Dentists and researchers have come up with the formula for the perfect smile, from the size and width of each tooth to the curve, colour and shape of the teeth, and the overall width of the smile.

Those pursuing perfection are advised to hide their gums, hold back on the bleach¹, cover the bottom teeth and set their lips at just the right angle."Everyone wants the perfect smile and Jessica Simpson is the one we get asked to reproduce the most," says Dr Nicholas Davis of Loma Linda University School of Dentistry.

According to the report, colour is important, and too many are now bleached² too white. Dr Davis said： "The teeth should be the same colour as the whites of your eyes. If the teeth are too white, they become more dominant³ than the eyes."There are strict mathematical ratios governing the ideal smile, says Dr Davis. Its width should be no less than half the of the face at the same height and, for the best effect, both upper and lower lips need to be symmetrical each side of the mid-line of the face.

牙医和研究学者已经研究出完美笑容秘诀，从每颗牙齿的大小、宽度到牙齿的曲线、颜色和形状以及张开的嘴宽度都有讲究。

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。洛马·林达大学牙医学院的尼古拉斯·戴维斯博士说：“每个人都想拥有完美笑容，而杰西卡·辛普森成为最多人模仿的对象。”

根据报告，颜色是很重要的，但现在不少人为拥有明眸皓齿不惜过渡漂白。戴维斯博士说：“牙齿与双眼最好一样白。如果牙齿太白，就会喧宾夺主。”戴维斯博士还表示，完美笑容有严格的数字比例。张开的嘴宽度不能小过半边脸的宽度，上唇与下唇两边嘴角要对称，如此才能交出最完美的笑容。