Kyoto Takemoto

A new concept of anatomic lingual arch form

INTRODUCTION The aim of this study was to describe a natural and anatomic lingual arch form obtained from subjects with normal occlusion that could be used, with other criteria, in the construction of personalized setups for the lingual straight-wire technique. METHODS The study sample comprised 58 pairs of dental casts of the arches of 58 southern Europeans (37 women, 21 men) with ideal natural occlusions. After the reference points of the dental arches were identified and marked, the dental casts were scanned. The exact position of the models on the scanner was established by using an acetate sheet with a Cartesian reference system. For each image, 14 reference points (x, y) were measured and recorded. The measurements were processed with software to select the polynomial function that best described the shape of the dental arches. The ninth-degree polynomial function was selected to represent the lingual arch form of both arches. Distribution analysis of the x and y values of each tooth in each arch resulted in the creation of 3 groups (small, medium, and large) to verify the most appropriate measures of the central tendencies of our data. RESULTS Statistical analysis showed no significant sex difference in the medians of the 6 parameters used to measure depth and width in both arches. A representation of the variability of the lingual curve of our sample was created to document at least 3 sizes of the representative curve of the central tendency for our data. No statistically significant differences in shape were found between men and women, considering the medians as a measure of the central tendencies. CONCLUSIONS Three lingual curves (small, medium, and large) for the maxillary and mandibular arches, representing the mean values of our sample, were developed and can be used as guides for the setup in the lingual straight-wire technique.

La technique linguale straight wire

The mushroom arch-wire is mainly used in lingual orthodontic treatment but the complicated wire bending it requires affects both the treatment results and the time spent at the chair. The author proposes a new lingual straight wire method (LSW) in order to facilitate arch coordination and simplify the mechanics. The attention paid to the set-up model and bracket positioning and bonding plus the use of the new LSW method will also improve patient comfort.Resume L’arc en forme de champignon est surtout utilise dans le traitement orthodontique lingual. Neanmoins, les pliures de fil compliquees determinent les resultats de traitement ainsi que le temps passe au fauteuil. L’auteur propose une nouvelle technique linguale straight wire (anglais : lingual straight wire method ou LSW) afin de faciliter la coordination des arcades et de simplifier la mecanique adoptee. Par ailleurs, en plus de la nouvelle methode LSW, l’attention portee au modele de set-up, a la position des brackets et au collage augmente le confort des patients.