Letters From Our Readers

To: Editor, The Angle Orthodontist, RE: The Form of The Human Arch

I have 2 questions concerning the article “The Form of the Human Arch,” published in Angle Orthod. 1998;68:29–36. Please let me know the answers.

If you substitute the mean depths and widths of dental arches into equation 2, the resulting formulas will be different from those printed on page 33 of the original article. For example, substituting the mean depth and width of Class II maxillary dental arch (D = 39.5 & W _ 51.1) into equation 2, you will have:

which is different from the fourth formula on page 33. What is the reason?

The mean depths and widths of all mandibular dental arches are greater than those of their respective maxillary ones. For example, the mean depth and width of Class I mandibular dental arches (D = 47.4 & W = 59.3) are greater than those of Class I maxillary dental arches (D = 40.7 & W = 53.0). How is it possible, knowing that, at least in Class I cases, maxillary dental arch usually covers mandibular 1?