Treatment effects of the bionator and high-pull facebow combination followed by fixed appliances in patients with increased vertical dimensions.
BACKGROUND
The purpose of this study was to evaluate the effectiveness of a first phase of bionator and high-pull facebow treatment followed by a second phase of fixed appliance therapy in growing subjects with increased vertical dimensions.


METHODS
The records of 24 subjects with high-angle skeletal relationships (mean MPA value approximately 30 degrees) treated consecutively with this protocol were examined. Cephalometric measurements were compared with those obtained from 23 sets of records of an untreated group matched according to age, gender, vertical skeletal relationships, and time intervals between records. The matched group of patients was from the University of Michigan Elementary and Secondary School Growth Study. Lateral cephalograms were analyzed prior to the start of treatment (T1, mean age 9.1 years), at the start of phase 2 treatment (T2, mean age 11.9 years), and after phase 2 treatment (T3, mean age 14.7 years). The total treatment duration (phase 1, retention, and phase 2) for the treated group was 5.5 years, whereas the control group total time interval averaged 5.6 years.


RESULTS
As to sagittal relationships, no significant differences were found between treated subjects and controls at the end of the 2-phase treatment for all measurements. Counterintuitively, the bionator and high-pull headgear combination worsened the hyperdivergent facial pattern at a clinically significant level, as shown by analysis of final facial forms. The treated group exhibited a significantly larger MPA value than controls (2.5 degrees) as well as a larger inclination of the Frankfort horizontal to the occlusal plane (2.8 degrees ).


CONCLUSIONS
Based on the analysis of this sample, the examined therapeutic protocol does not appear to be a recommendable option for treatment of subjects with increased vertical dimensions.
Freeman
Christopher S
CS
Graduate Orthodontic Program, University of Michigan, Ann Arbor, Mich 48109-1078, USA.
McNamara
James A
JA
Baccetti
Tiziano
T
Franchi
Lorenzo
L
Graff
Theodore W
TW
D000202:Activator Appliances; D000293:Adolescent; D000365:Age Determination by Skeleton / Q000379:methods; D016022:Case-Control Studies; D002508:Cephalometry / Q000379:methods; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging*; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008311:Malocclusion, Angle Class I / Q000628:therapy; D008312:Malocclusion, Angle Class II / Q000628:therapy; D009971:Orthodontics, Corrective / Q000295:instrumentation* / Q000379:methods; D014716:Vertical Dimension