Growth & Development
Michelle Kwan, DDS
PGY-2
Boston Children’s Hospital/Harvard School of Dental Medicine, Boston, MA
Boston Children's Hospital/Harvard School of Dental Medicine
Boston, Massachusetts, United States
Zameera Fida, DMD
Pediatric Dental Attending
Boston Children's Hospital
Boston Children's Hospital
Boston, Massachusetts, United States
Zameera Fida, DMD
Pediatric Dental Attending
Boston Children's Hospital
Boston Children's Hospital
Boston, Massachusetts, United States
Isabelle Chase, DDS, FRCD(C)
Program Director
Boston Children's Hospital
Harvard School of Dental Medicine
Boston, Massachusetts, United States
Purpose: To assess mesialization of mandibular second permanent molars after first permanent molar extraction to inform long-term orthodontic and restorative outcomes. We hypothesize that chronological age and Demirjian developmental stage of the SPM are significantly associated with successful space closure in the mandibular arch. We also aim to evaluate whether mesial angulation is significantly associated.
Methods: In this IRB approved retrospective chart review, 830 patient charts from the Boston Children’s Department of Dentistry and Department of Oral and Maxillofacial Surgery between 2013-2023 were reviewed. Pre-extraction panoramic or periapical radiographs were evaluated for predictive independent variables: chronological age, second permanent molar Demirjian developmental stage, second permanent molar angulation, and developing third molar. Post-extraction bitewing or panoramic radiographs were evaluated for complete or acceptable space closure between second permanent molar and second premolar. Logistical regression was used to examine continuous variables association on the success of closure, with chi-square used to examine individual independent binary variables association with rates of closure.
Results: Fifty-four mandibular quadrants with first permanent molar extractions were included. There was a significant reduction in the success of space closure in patients with increase in age (OR = 0.32, p < .001). On sub-analysis, patients aged 7-10 exhibited significant increase in success of space closure compared to ages >10 (OR = 0.03, p < .001). When adjusted for angulation, age continued to show significance in increasing occurrence of space closure (OR = 0.03, p <.001). When adjusted for angulation and Demirjian stage, age continued to show significance in increased occurrence of space closure (OR = 0.33, p < .05). There was a significant increase in the success of space closure associated with Demirjian stage D and E (p < .001). Quadrants with mesial angulation of SPM had a significantly higher occurrence of space closure when compared to those with upright angulation (p = .004). Developing third molars were present in 94% of quadrants.
Conclusion: In patients with mandibular first permanent molar extractions, age was significantly associated with space closure when adjusted for SPM developmental stage and SPM angulation. When independently examined, early age, early Demirjian stage, and mesial SPM angulation were associated with increased occurrence of space closure. Our results confirm our hypothesis and support previous literature findings and the importance of the listed factors in determining space closure success.