Long-term evaluation of Class II subdivision treatment with unilateral maxillary first molar extraction.
OBJECTIVE
To evaluate the long-term effects of asymmetrical maxillary first molar (M1) extraction in Class II subdivision treatment.


METHODS
Records of 20 Class II subdivision whites (7 boys, 13 girls; mean age, 13.0 years; SD, 1.7 years) consecutively treated with the Begg technique and M1 extraction, and 15 untreated asymmetrical Class II adolescents (4 boys, 11 girls; mean age, 12.2 years; SD, 1.3 years) were examined in this study. Cephalometric analysis and PAR assessment were carried out before treatment (T1), after treatment (T2), and on average 2.5 years posttreatment (T3) for the treatment group, and at similar time points and average follow-up of 1.8 years for the controls.


RESULTS
The adjusted analysis indicated that the maxillary incisors were 2.3 mm more retracted in relation to A-Pog between T1 and T3 (β  =  2.31; 95% CI; 0.76, 3.87), whereas the mandibular incisors were 1.3 mm more protracted (β  =  1.34; 95% CI; 0.09, 2.59), and 5.9° more proclined to the mandibular plane (β  =  5.92; 95% CI; 1.43, 10.41) compared with controls. The lower lip appeared 1.4 mm more protrusive relative to the subnasale-soft tissue-Pog line throughout the observation period in the treated adolescents (β  =  1.43; 95% CI; 0.18, 2.67). There was a significant PAR score reduction over the entire follow-up period in the molar extraction group (β  =  -6.73; 95% CI; -10.7, -2.7). At T2, 65% of the subjects had maxillary midlines perfectly aligned with the face.


CONCLUSIONS
Unilateral M1 extraction in asymmetrical Class II cases may lead to favorable occlusal outcomes in the long term without harming the midline esthetics and soft tissue profile.
a  Staff Member, Department of Orthodontics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
Christos
C
Livas
b  Visiting Assistant Professor, Department of Orthodontics and Dentofacial Orthopedics, School of Dental Medicine, University of Bern, Bern, Switzerland; and Private Practice, Corfu, Greece.
Nikolaos
N
Pandis
c  Orthodontist, Private Practice, Gorinchem, The Netherlands.
Johan Willem
JW
Booij
d  Professor and Chair, Department of Orthodontics and Dentofacial Orthopedics, School of Dental Medicine, University of Bern, Bern, Switzerland.
Christos
C
Katsaros
e  Professor and Chair, Department of Orthodontics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
Yijin
Y
Ren
D000293:Adolescent; D002508:Cephalometry / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D008437:Maxilla; D008963:Molar / Q000473:pathology*; D014081:Tooth Extraction
Cephalometrics; Class II subdivision; Maxillary first molar extraction; PAR