Accuracy of surgical positioning of orthodontic miniscrews with a computer-aided design and manufacturing template

Cheng

et al. 2014

PLoS ONE

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ObjectiveThe purpose of this study was to evaluate the morphological changes of upper airway after Twin Block (TB) treatment in growing patients with Class II division 1 malocclusion and mandibular retrusion compared with untreated Class II patients by cone beam computed tomography (CBCT).Materials and MethodsThirty growing patients who have completed TB treatment were recruited into TB group. The control group (n = 30) was selected from the patients with the same diagnosis and without TB treatment. CBCT scans of the pre-treatment (T1) and post-treatment (T2) data of TB group and control data were collected. After three-dimensional (3D) reconstruction and registration of T1 and T2 data, the morphological changes of upper airway during TB treatment were measured. The statistical differences between T1 and T2 data of TB group as well as T2 and control data were accessed by t-test.ResultsDuring the TB treatment, the mandible moved advanced by 3.52±2.14 mm in the horizontal direction and 3.77±2.10 mm in the vertical direction. The hyoid bone was in a more forward and inferior place. The upper airway showed a significant enlargement in nasopharynx, oropharynx and hypopharynx. In addition, the nasopharynx turned more circular, and the oropharynx became more elliptic in transverse shape. However, the transverse shape of the hypopharynx showed no significant difference. After comparison between T2 and control data, only the horizontal movement of the hyoid bone, the volumetric expansion of the oropharynx and hypopharynx, and changes of the oropharyngeal transverse shape showed significant difference.ConclusionCompared to the untreated Class II patients, the upper airway of growing patients with Class II division 1 malocclusion and mandibular retrusion showed a significant enlargement in the oropharynx and hypopharynx as well as a more elliptic transverse shape in the oropharynx, and the hyoid bone moved to an anterior position after TB treatment.

Section: Introductionmentioning

confidence: 99%

CBCT Evaluation of the Upper Airway Morphological Changes in Growing Patients of Class II Division 1 Malocclusion with Mandibular Retrusion Using Twin Block Appliance: A Comparative Research

Cheng

et al. 2014

PLoS ONE

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“…14 Multislice computed tomography (MSCT) registration might be an acceptable imaging technique supplying quantitative assessment of the upper airway changes in clinics, 15,16 and this method might permit an accurate topographical calculation of the upper airway displacements with subvoxel accuracy after identification of the cranial base structures. 17,18 In addition, compared with magnetic resonance imaging, MSCT can offer an alternative to reduce the time required to reduce the breathing effects on airway volume. Therefore, this retrospective, analytical study was designed to evaluate the upper airway morphology changes occurring after large incisor retraction in patients with adult bimaxillary malocclusion by retrospective 3D registration.…”

Section: Introductionmentioning

confidence: 99%

Effect of large incisor retraction on upper airway morphology in adult bimaxillary protrusion patients

Chen

Wang

et al. 2012

The Angle Orthodontist

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Objective: To evaluate, using multislice computed tomography (MSCT), the morphologic changes in the upper airway after large incisor retraction in adult bimaxillary protrusion patients. Materials and Methods: Thirty adult patients with bimaxillary protrusion had four first premolars extracted, and then miniscrews were placed to provide anchorage. A CT scan was performed before incisor retraction and again posttreatment. Three-dimensional (3D) reconstruction of the pre-(T1) and post-(T2) CT data was used to assess for morphological changes of the upper airway. A paired t-test was used to compare changes from T1 to T2. The relationship among the three variables (upper incisor retraction amount, upper airway size, and hyoid position) was analyzed by Pearson correlation coefficient. Results: The amounts of upper incisor retraction at the incisal edge and apex were 7.64 6 1.68 mm and 3.91 6 2.10 mm, respectively. The hyoid was retracted 2.96 6 0.54 mm and 9.87 6 2.92 mm, respectively, in the horizontal and vertical directions. No significant difference was observed in the mean cross-sectional area of the nasopharynx (P . .05) between T1 and T2, while significant differences between T1 and T2 were found in the mean cross-sectional areas of the palatopharynx, glossopharynx, and hypopharynx (P , .05); these mean cross-sectional areas were decreased by 21.02% 6 7.89%, 25.18% 6 13.51%, and 38.19% 6 5.51%, respectively. The largest change in the cross-sectional area is always noted in the hypopharynx. There was a significant correlation among the retraction distance of the upper incisor at its edge, the retraction distance of the hyoid in the horizontal direction, and the decrease of the hypopharynx. Conclusion: Large incisor retraction leads to narrowing of the upper airway in adult bimaxillary protrusion patients. (Angle Orthod. 2012;82:964-970.)

“…Cone beam computed tomography (CBCT) cannot quantify the dentoalveolar changes by pre-and post-treatment 3D registration, due to lack of stable references with 3D craniofacial model (Cevidanes et al, 2010). CT scanning might be an acceptable imaging technique supplying a quantitative assessment of upper alveolar bone by CT registration in clinics (Nelson and Michael, 1998), and might permit an accurate topographical calculation of alveolar bone displacements (Liu et al, 2010). Therefore, this study was designed to evaluate maxillary alveolar bone morphology after incisor retraction and intrusion in adult bimaxillary malocclusion by retrospective 3D registration.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional evaluation of upper anterior alveolar bone dehiscence after incisor retraction and intrusion in adult patients with bimaxillary protrusion malocclusion

Guo

Zhang

J. Zhejiang Univ. Sci. B

et al. 2011

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Abstract:Objective: The purpose of this study was to evaluate three-dimensional (3D) dehiscence of upper anterior alveolar bone during incisor retraction and intrusion in adult patients with maximum anchorage. Methods: Twenty adult patients with bimaxillary dentoalveolar protrusion had the four first premolars extracted. Miniscrews were placed to provide maximum anchorage for upper incisor retraction and intrusion. A computed tomography (CT) scan was performed after placement of the miniscrews and treatment. The 3D reconstructions of pre-and post-CT data were used to assess the dehiscence of upper anterior alveolar bone. Results: The amounts of upper incisor retraction at the edge and apex were (7.64±1.68) and (3.91±2.10) mm, respectively, and (1.34±0.74) mm of upper central incisor intrusion. Upper alveolar bone height losses at labial alveolar ridge crest (LAC) and palatal alveolar ridge crest (PAC) were 0.543 and 2.612 mm, respectively, and the percentages were (6.49±3.54)% and (27.42±9.77)%, respectively. The shape deformations of LAC-labial cortex bending point (LBP) and PAC-palatal cortex bending point (PBP) were (15.37±5.20)° and (6.43±3.27)°, respectively. Conclusions: Thus, for adult patients with bimaxillary protrusion, mechanobiological response of anterior alveolus should be taken into account during incisor retraction and intrusion. Pursuit of maximum anchorage might lead to upper anterior alveolar bone loss.