Relationship between the amount of mesial movement of the mandibular first molar and angular changes of the mandibular third molar: A retrospective comparative study in growing patients with and without first premolar extraction
Fatemeh Azizi , Ali Naghib Zadeh , Amin Golshah , Mohammad Moslem Imani , Roya Safari-Faramani
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引用次数: 0
Abstract
Objectives
The main objective of this study was to assess the relationship of the amount of mesial movement of mandibular first molar (MFM) and angular changes of the mandibular third molar (MTM) in orthodontic patients. The secondary objective of this study was to compare the obtained values in extraction and non-extraction orthodontic patients.
Material and methods
In this cross-sectional retrospective study were enrolled all the eligible patients (12–16 years) with and without first premolar extraction that met the inclusion criteria. The angle between the longitudinal axis of MTM and horizontal reference plane (HRP) (to calculate the angular change of MTM), and the distance between the cementoenamel junction of the mesial surface of MFM and the bisector of the anterior nasal spine and nasal septum (to determine the amount of mesial movement of MFM) were measured on pre- and post-treatment panoramic radiographs. The correlation between the two variables was analysed and compared between extraction and non-extraction patients using STATA v. 14.2 software.
Results
A total of 100 fixed orthodontic patients with and without first premolar extraction (n = 50) whose treatment had been accomplished were included in the study. In the non-extraction group, the mean amount of mesial movement of MFM was 1.45 mm and the mean angular change of MTM was 4.28 degrees; this correlation was significant (P < 0.05). These values were 2.98 mm and 7.17 degrees in the first premolar extraction group, respectively, with a significant correlation (P < 0.05). However, the difference in this respect was not significant between the two groups (P > 0.05). According to the regression model, 1 mm mesial movement of MFM would averagely cause 2.2-degree angular change in MTM, adjusting for the effect of extraction/non-extraction treatment plan.
Conclusion
The mesial movement of MFM was significantly correlated with the angular changes of MTM in extraction and non-extraction orthodontic patients, with no significant difference between them.
期刊介绍:
Une revue de référence dans le domaine de orthodontie et des disciplines frontières Your reference in dentofacial orthopedics International Orthodontics adresse aux orthodontistes, aux dentistes, aux stomatologistes, aux chirurgiens maxillo-faciaux et aux plasticiens de la face, ainsi quà leurs assistant(e)s. International Orthodontics is addressed to orthodontists, dentists, stomatologists, maxillofacial surgeons and facial plastic surgeons, as well as their assistants.