Journal Article

Third molar influence on dental arch crowding

Iwona Niedzielska

in The European Journal of Orthodontics

Published on behalf of European Orthodontics Society

Volume 27, issue 5, pages 518-523
Published in print October 2005 | ISSN: 0141-5387
Published online August 2005 | e-ISSN: 1460-2210 | DOI:
Third molar influence on dental arch crowding

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  • Restorative Dentistry and Orthodontics


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The aim of the present study was to measure the dental arches in order to assess the potential influence of third molars on lower incisor crowding. Changes in dental arch dimensions were assessed in 47 patients (36 females, 11 males) three years following either removal of the third molars or deciding to leave them in situ. A dental pantomogram (DPT) was taken at the start of the study and plaster study models were obtained at both the beginning and end of the observation period. The study models were used to measure crowding, and to prepare photocopies for linear measurements of the dental arch (length and width). Using the DPT, the ratio of retromolar space to the width of the crown of the third molar was calculated using the method originally described by Olive and Basford and later modified by Ganss (Ganss ratio).

The results showed that the measurements of crowding and arch length and width had changed in 12 lower and two upper dental arches. The relationship between these results and the Ganss ratio was statistically significant. Calculation of the Ganss ratio may therefore assist investigations into the development of dental arch crowding and also help determine the indications for third molar removal.

Journal Article.  3902 words.  Illustrated.

Subjects: Restorative Dentistry and Orthodontics

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