Spontaneous Space Closure After the Extraction of the Permanent First Molar on Mandibular Arch: A Retrospective Study

Abstract

Background: First permanent molars (FPMs) with poor prognosis are generally extracted during the early formation of bifurcation of second permanent molars (SPMs) in order to achieve spontaneous space closure. The literature is limited about the factors associated with spontaneous space closure for mandibular arch. The aim of this study was to determine the prognostic radiographic factors, such as developmental stage of SPM, angulation of SPM and presence/absence of the third molar associated with the spontaneous space closure after the FPM extraction. Methods: A total of 177 mandibular SPMs were included in this study. The prognostic factors determining successful space closure such as SPM developmental stage, SPM angulation using a measurement scale, and presence /absence of the third molar on the panoramic radiograph were evaluated. Results: The mean age of the patients at the time of extraction of SPM was 9.4 years and post-extraction radiographic assessment at the time of the study was 12.7 years. Out of the total 177 mandibular SPMs, 36 SPMs (20.3%) were at Demirjian stage D, 63 (35.6%) at stage E, 60 (34%) at stage F, 18 (10.1%) at stage G. 16 SPMs (9%) have distal angulation, 21 SPMs (11.8%) have mesial angulation and 140 SPMs(79.1%) have upright angulation. At the time of radiographic assessment, 80.2% of the mandibular quadrants showed evidence of third molar formation. Out of 177 mandibular SPMs, only 105 (59.3%) exhibited successful space closure in the mandibular arch. Conclusions: There is no statistically significance between the chronological age and the developmental stage of the mandibular SPM with the successful spontaneous space closure at the time of the dental extraction of FPMs. The presence of the mandibular third molar may be considered for the spontaneous space closure in mandibular arch. Keywords : Extraction of Permanent Molar, Measurement Scale, Spontaneous space closure