Early extractions of premolars reduce age-related crowding of lower incisors: 50 years of follow-up

Maurits Persson,Anna Westerlund,Nameer Al-Taai,Karin Pihlgren

doi:10.1007/s00784-022-04416-x

Abstract

ObjectivesTo study the effects of extraction of four premolars, without subsequent orthodontic treatment, on the crowding of lower incisors in subjects between early adolescence and late adulthood, as compared to untreated subjects.Materials and methodsA total of 45 subjects were included in this study. The extraction group comprised 24 subjects who had all the first premolars removed at a mean age of 11.5 years, to relieve crowding in a class I malocclusion without subsequent orthodontic treatment. The control group had 21 untreated subjects, having a normal occlusion at a mean age of 13.0 years. The participants were documented with dental casts and cephalograms at mean ages of 11.4 and 13.0 years, for the two groups respectively (T1), and at mean ages of 30.9 years (T2) and 61.7 years (T3). Changes in lower incisor crowding were described as changes in “irregularity” and “space deficiency.”ResultsThe extraction group showed no changes in the irregularity of the lower incisors and significant improvement of the space deficiency of the lower teeth into late adulthood. While in the control group, both irregularity of the lower incisors and space deficiency of the lower teeth increased significantly into late adulthood.ConclusionLower incisor alignment remains mainly unchanged into late adulthood in subjects who have all their first premolars removed in childhood, as the only treatment to relieve teeth crowding.Clinical relevanceSevere crowding in a class I occlusion can be solved solely with premolar extraction, allowing for spontaneous adjustments with more stable incisor alignment up to late adulthood.

Highlights

Crowding is the most frequent malocclusion [1, 2] and is the most common reason why many adults seek orthodontic treatment [2, 3]
The total reduction in incisor tooth width with age from T1 to T3 was − 0.4 mm in the extraction group and − 0.8 mm in the control group, with no significant differences within or between the groups over time (Table 2)
The changes in the Irregularity Index of the extraction group were non-significant from early adolescence to early adulthood (T1–T2), as well as early to late adulthood (T2–T3)

Summary

Introduction

Crowding is the most frequent malocclusion [1, 2] and is the most common reason why many adults seek orthodontic treatment [2, 3]. Crowding of the front teeth, especially the lower incisors, is considered to be the most pronounced, Maurits Persson and Nameer Al-Taai contributed to this work. The mechanisms underlying age-related lower incisor crowding, both in treated and untreated subjects, are still not well understood. Lower incisor crowding has been attributed to multiple factors, including mesial migration of the posterior teeth and lingual inclination of the incisors [9, 17,18,19]. Extraction of all the first premolars with subsequent orthodontic treatment is the most commonly used method to relieve dental crowding. The significance and timing of extraction as part of the orthodontic treatment for late incisor

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Conclusion