1. Annemarie Holm, Marie A. Cornelis, Paolo M. Cattaneo
94th EOS Congress
Edinburgh / June
A Three-dimensional evaluation of skeletal and dentoalveolar changes in growing Class II patients after functional appliance therapy
Annemarie Holm, Marie A. Cornelis, Paolo M. Cattaneo
Section of Orthodontics – Department of Dentistry
Aarhus University - Denmark
A A R H U S U N I V E R S I T E T
Paolo M. Cattaneo

4. Aim of the study
The aim of this study was to assess three-dimensionally mandibular and maxillary changes in growing Class II patients, treated with removable functional appliances followed by fixed appliances.

5. Reseach design Retrospective study Test group:
24 Class II patients (14 female, 10 male)
Age range years (mean age: /- 1.1)
Treated with removable functional appliances followed by fixed appliances
3D digital models and CBCT-scans before and after active treatment
Control group:
18 skeletal Class I and mild Class II patients (13 female, 5 male)
Age range years (mean age: 12.7 ± 0.9)
9 Twin Block
8 Maxillator
4 Ergenzinger activator
2 Bass activator
1 Modified Andreasen activator

6. Method A new 3D method for cephalometric analysis was developed
33 reference points
Constructed reference planes
Stable structures of the cranial base
To carry out the ceph. Analysis we made a new method where we used 33 reference points and lines previously defined by Björk in 2D.
All the midsagittal points were identified on the midsagittal plane to simulate what we normally do in 2D. The position of the landmarks were then checked on the coronal and axial plane.
All the bilateral points like gonion for ex. were identified on the 3D surface and fine-adjusted by checking and relocating them in the sagittal, axial and coronal views.
Ba-S-N (Sagittal plane)
S-cribriform plate- perp. To the sagittal plane (Axial plane)
S-perp. To axial and sagittal plane (Coronal plane)

7. Statistics
Descriptive measurements of all measured and calculated variables
Shapiro-Wilk test and Q-Q plots
Intra-group differences assed by paired t-test
Inter group differences assed by independent sample t-test
Dahlberg’s formula
Bland-Altman plots
The statistical analysis was carried out using SPSS
Including means, standard deviations, minimum and maximum values of all measured and calculated variables were performed
Shapiro-Wilk test and Q-Q plots to test for normality, the data were found to be normally destributed.
Dahlberg’s formula to calculate the technical error of the method
Bland-Altman plots to asses the mean difference in measurements between the two operators and to quantify the range of agreement.

8. Results Baseline Data Significant inter-group differences: Measurement
Test group
Control group
Comparison
Mean SD
P-value
Overjet (mm)
8.9
2.8
4.0
1.7
0.00
ANB (°)
5.7
2.0
3.2
1.4
SNB (°)
74.4
3.4
76.6
4.7
0.04
Ramus length (mm)
50.6
54.0
4.1
Effective mandibular length (mm)
112.5
116.9
5.9
0.01
Wits appraisal (mm)
5.6
2.7
0.5
1.5
Upper central incisor inclination (°)
67.3
6.5
72.5
6.6
0.02
Baseline data shows that there were significant differences between FA-group and the control group when looking at Overjet, ANB, SNB, Ramus length, effective mandibular length, wits appraisal and upper incisor inclination

9. Results Treatment effect: Overjet reduction of 6.8 ± 2.8 mm
Retroclination of upper central incisors (6.4 ± 7.5 degrees)
Proclination of lower central incisors (8.9 ± 4.9 degrees)
Ramus length increased by 4.5 ± 2.2 mm
Corpus mandibular length increased 3.8 ± 1.8 mm
Effective mandibular length increased by 6.3 ± 2.6 mm
Avarage treatment time 26 months.
All measurements had a statistical significant difference in the FA group except SNB and SNBa angle.

10. Results Comparison of treatment effect between the groups:
All subjects ended with a normal overjet 2 mm
No statistical difference in SNB angle
Ramus length positive mean difference 1.5 mm
Corpus mandibular length positive mean difference 1.3 mm
Effective mandibular length positive mean difference 2.4 mm
2.4 mm corresponds to more than 60% increase in growth of the mandible in the FA group compared to the control group. With this growth adaptation, the pt’s in the FA group nearly caught up with the controls and only lacked mm of effective mandibular length after treatment.

11. Conclusion
The results indicate that functional appliances are effective in correcting Class II malocclusions. The observed growth adaptation in the functional appliance group resulted in an increase of mandibular length.
Yet, the final length of the mandible in the functional appliance group was smaller when compared to the control group.

12. Thank you for your attention!
Section of Orthodontics – Department of Dentistry
Aarhus University - Denmark