Korean J Orthod.  2020 May;50(3):170-180. 10.4041/kjod.2020.50.3.170.

Evaluation of growth changes induced by functional appliances in children with Class II malocclusion: Superimposition of lateral cephalograms on stable structures

• Oh E
• Ahn SJ
• Sonnesen L

• KMID: 2502626
• DOI: http://doi.org/10.4041/kjod.2020.50.3.170

Abstract

Objective
To compare short- and long-term dentoalveolar, skeletal, and rotational changes evaluated by Björk’s structural method of superimposition between children with Class II malocclusion treated by functional appliances and untreated matched controls.
Methods
Seventy-nine prepubertal or pubertal children (mean age, 11.57 ± 1.40 years) with Class II malocclusion were included. Thirty-four children were treated using an activator with a high-pull headgear (Z-activator), while 28 were treated using an activator without a headgear (E-activator). Seventeen untreated children were included as controls. Lateral cephalograms were obtained before treatment (T1), after functional appliance treatment (T2), and after retention in the postpubertal phase (T3). Changes from T1 to T2 and T1 to T3 were compared between the treated groups and control group using multiple linear regression analysis.
Results
Relative to the findings in the control group at T2, the sagittal jaw relationship (subspinalenasion- pogonion, p < 0.001), maxillary prognathism (sella-nasion-subspinale, p < 0.05), and condylar growth (p < 0.001) exhibited significant improvements in the Z- and E-activator groups, which also showed a significantly increased maxillary incisor retraction (p < 0.001) and decreased overjet (p < 0.001). Only the E-activator group exhibited significant backward rotation of the maxilla at T2 (p < 0.01). The improvements in the sagittal jaw relationship (p < 0.01) and dental relationship (p < 0.001) remained significant at T3. Condylar growth and jaw rotations were not significant at T3.
Conclusions
Functional appliance treatment in children with Class II malocclusion can significantly improve the sagittal jaw relationship and dental relationships in the long term.

Keyword

Class II malocclusion; Functional appliance; Growth evaluation; Superimposition

Figure

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  Figure 1 Functional appliances used in the present study. A and B, Z-activator (Teuscher activator with a high-pull headgear)10. C, E-activator (modified Andresen activator, also known as an Ergenzinger activator).11

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  Figure 2 Cephalometric landmarks used for measurements.14 n, Nasion; s, sella; cd, condylion; ba, basion; ar, articulare; gn, gnathion; pg, pogonion; sm, supramentale; isi, incisal superior incisor; iii, incisal inferior incisor; ss, subspinale; sp, spinale; MBLar, mandibular base line; Rlar, ramus line; ILi, incisal line inferior; ILs, incisal line superior; ML, mandibular line; NL, nasal line.

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  Figure 3 Illustration of superimposition on the stable structures in the anterior cranial base between two stages.9 NSLRef, Nasion-sella line at before treatment (T1) transferred to the following lateral cephalogram as a reference line when the two sets are superimposed on the stable structures in the anterior cranial base; MaxillaRef, a reference line drawn in the maxilla when the two sets are superimposed on the stable structures in the maxilla; MandibleRef, a reference line drawn in the mandible when the two sets are superimposed on the stable structures in the mandible.

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  Figure 4 Illustration of superimposition on the stable structures in the maxilla between two stages.9 MaxillaRef, Maxillary reference line; ILs1, incisal line superior stage 1; ILs2, incisal line superior stage 2; isi1, incisal superior stage 1; isi2, incisal superior stage 2.

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  Figure 5 Illustration of superimposition on the stable structures in the mandible between two stages.9 cd, Condylion; cdRef, condylion at baseline (T1); MandibleRef, mandibular reference line; ILi1, incisal line inferior stage 1; ILi2, incisal line inferior stage 2; iii1, incisal inferior stage 1; iii2, incisal inferior stage 2.

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