Steiner’s cephalometric norms for the Nepalese population

Abstract

Objective: To establish the Steiner’s cephalometric norms for a Nepalese population, compare the gender and inter‐racial variations in dentoskeletal and soft tissue structures, and to test the null hypothesis that there are no racial differences in cephalometric measurements between Nepalese, Caucasians and other populations.

Design: Prospective, cross‐sectional study.

Subjects and methods: One hundred and twenty lateral cephalograms of Nepalese subjects aged 16–21 years with class I normal occlusion and balanced facial aesthetics were selected. The cephalometric variables were measured. An independent one sample t test was used to compare the Steiner’s ideal values with Indo‐Aryan Nepalese means and independent t test to compare Japanese means with Mongoloid Nepalese means and Mongoloids with Aryans. Intra‐investigator error was assessed with Lin’s concordance method and the reliability of aesthetic evaluation of the photographs was tested with Cronbach’s alpha.

Results: Nepalese Mongoloid males possessed more protrusive lips (Z angle mean difference, 8°; P<0·001) than the Indo‐Aryan males. Mongoloid females had more protrusive mandible (SNB angle mean difference, 3·7°; P<0·001), greater class II skeletal bases (SND angle mean difference, 3·5°; P<0·001), longer SL length (mean difference, 5·6 mm; P<0·01), more proclined upper incisors (U1–NA mean difference, 6°; P<0·01) and a more protrusive lower lip (lower lip–S line mean difference, 0·9 mm; P = 0·003), lower lip–E line (2·0 mm; P<0·001) and Z angle (4·4°; P<0·001), than the Indo‐Aryan females. Differences between the Nepalese sample and published Caucasian and Japanese norms are also described.

Conclusions: Differences in the cephalometric values exist between the two ethnic groups in Nepal, as well as between our Nepalese sample and published Caucasians and Japanese norms. The norms published in this article will be useful when planning orthodontic treatment in Mongoloid and Indo‐Aryan individuals.

Keywords:

• Cephalometric norms
• Nepalese population
• Steiner’s analysis
• racial variations

Acknowledgments

The author is grateful to Scientific Committee of BP Koirala Institute of Health Sciences for approval and funding this research project. He thanks Mr D. D. Boral and Dr Surya Raj Niraula for statistical analysis, Dr Malcolm Moore for English language corrections, Dr Prekshya Dali, Dr Charu Sharma, Dr Arati Sharma and Mr Sandeep Khanal for their valuable contributions.