Effect of functional appliances on sleep-disordered breathing in Class II division 1 malocclusion children: Randomized controlled trial

A comparative study of Twin-Block and van Beek Headgear-Activator on the three-dimensional morphology of the upper airway in growing children with mandibular retraction in skeletal class II malocclusion

OBJECTIVES

To compare the variations in the upper airway of children with skeletal Class II mandibular retrognathism treated with van Beek Headgear-Activator (vBHGA) and Twin-Block (TB) appliances.

MATERIALS AND METHODS

40 children were involved in this retrospective study and divided into two intervention groups: the vBHGA group and the TB group, each comprising 20 individuals with an average age of 11.13 years. Employing Cone Beam Computed Tomography and Geometric Morphometric analysis, a comprehensive assessment of the upper airway's volume, minimum cross-sectional area (m-CSA), and 3D shape characteristics was conducted pre-and post-treatment.

RESULTS

The total volume, oropharynx volume, oropharynx m-CSA, and hypopharynx m-CSA significantly increased in both the vBHGA and TB groups (p < 0.05). The sole discrepancy between the two groups was observed in comparing the nasopharynx m-CSA (p < 0.05). A morphological difference was observed in the vBHGA group before and after treatment (p < 0.05), characterized by a wider and shorter airway, positioning of the posterior nasal spine closer to the anterior inferior area, and a more posterior nasopharyngeal wall. However, there were no significant shape differences between the two groups or before and after treatment within the TB group.

CONCLUSION

It appears that both vBHGA and TB interventions contribute positively to alleviating upper airway constriction. Nonetheless, the vBHGA group exhibits more alterations in the configuration of the nasopharynx.

CLINICAL RELEVANCE

Both orthodontic appliances have a positive impact on the upper airway but still have differences, emphasizing the need for individualized consideration when selecting orthodontic interventions.

CLINICAL TRIAL REGISTRATION

This study was also registered with the Chinese Clinical Trial Registry with registration number ChiCTR2400086867.

A finite element study comparing Advansync® and Twin Block in mandibular anterior repositioning

OBJECTIVE

This study aims to utilize the finite element method (FEM) to compare the dentoalveolar and mandibular effects associated with anterior mandibular repositioning using AdvanSync® (ADV) and Twin Block (TB).

METHODS

A patient with Class II skeletal malocclusion and mandibular retrognathism was selected. A TB appliance was subsequently applied. Computed Tomography (CT) scans were acquired at the beginning of treatment (T1) and 8 months later (T2). Concurrently, a numerical TB model was validated through FEM simulations, which were compared with the T2 results. The ADV appliance was virtually simulated to evaluate stress and deformation on the condyle, symphysis, first lower molar and lower central incisors.

RESULTS

Both simulations demonstrated significant mandibular advancement. However, ADV led to less incisor proclination and more molar intrusion compared to TB. ADV exhibited increased stress in the lower molar area, while TB had higher stress in the lower incisor region. Stress and deformations in the condyle and mandibular symphysis were similar in both simulations, with the highest stress observed at the condylar neck and the lowest at the upper pole of the condylar head.

CONCLUSIONS

Both appliances achieved similar levels of mandibular advancement, with greater proclination of the lower central incisors and more widespread distribution of stress and molar intrusion when using ADV compared to TB.