Change in the mesiodistal axial inclination of the maxillary lateral teeth during the mixed dentition stage: Morphometric analysis of panoramic radiographs from two cases of mild crowding with a high canine

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Date: January-February 2016
From: APOS Trends in Orthodontics(Vol. 6, Issue 1)
Publisher: Medknow Publications and Media Pvt. Ltd.
Document Type: Report
Length: 3,169 words
Lexile Measure: 1440L

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Byline: Morio. Masunaga, Hiroshi. Ueda, Tatsuya. Shibaguchi, Kazuo. Tanne

Objective: The aim of this study was to investigate the changes of the mesiodistal axial inclination of the maxillary lateral teeth relative to the functional occlusal plane (FOP) on panoramic radiographs in patients with Angle Class I maxillary anterior crowding with high canines during the mixed dentition stage. Materials and Methods: Panoramic radiographs were used to measure the mesiodistal axial inclination of the teeth before orthodontic treatment in Cases 1 and 2. The long axes of the teeth were determined according to the previous study by Ursi et al. Finally, the angles between the long axes of teeth and the FOP were measured. Results: The first premolar and canine showed mesial tipping in the alveolar bone during eruption. The crown of the second premolar was located close to the apex of the first molar and showed excessive mesial inclination relative to the long axis of the second deciduous molar. Before orthodontic treatment, considerable autonomous changes in the mesiodistal inclination were found in the canine and the second premolar in the maxillary alveolar bone during eruption. With respect to the first molar, the mesiodistal inclination was invariable, or the angle was almost 90[degrees] without any significant change during the observation period. Conclusions: Based on the results of this study, two new findings are described. Autonomous changes in the inclination of the mesiodistal maxillary teeth were observed during exfoliation, particularly in the canine and second premolars. In addition, the eruption of the maxillary lateral teeth influenced the neighboring teeth, whereas the first molar maintained an environmentally defined position.

Introduction

Crowding is a type of malocclusion characterized by irregularly positioned teeth caused by an arch length discrepancy (ALD). According to an etiologic survey, the incidence of crowding is high compared with other types of malocclusion.[sup][1],[2],[3],[4] Tooth size is an important determinant of crowding.[sup][4],[5],[6],[7],[8],[9] In a biometric study, Doris et al .,[sup][4] found that patients with crowded dentition due to an ALD >4 mm consistently had larger teeth than those with less or no crowding. By contrast, Howe et al .[sup][10] found no significant differences in tooth size between dentitions with and without crowding. The relationship between crowding and arch dimensions has also been studied.[sup][11],[12],[13] Bernabe et al .[sup][11] showed that crowding was associated with smaller arch dimensions. Moreover, several other factors, such as the early loss of deciduous molars,[sup][14] oral and perioral musculature,[sup][14] and direction of mandibular growth,[sup][15],[16] are assumed to affect the development and severity of crowding.

A maxillofacial panoramic radiography analysis was carried out in this study. Panoramic radiography has been used extensively for orthodontic diagnosis and treatment planning because of the simplicity of the procedure, the low radiation dosage, and the ability to widely project the structures with reduced overlap with the intervening tissues.[sup][15],[16] However, panoramic radiography always includes a certain amount of image distortion due to the discrepancy between the horizontal and vertical magnification.[sup][17] Although horizontal measurements, in particular, are not accurate enough for absolute determination, the angular distortion is...

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Gale Document Number: GALE|A439912765