Residents’ journal review

Transverse changes with clear aligners

Houle JP, Piedade L, Todescan R Jr, Pinheiro FH. The predictability of transverse changes with Invisalign. Angle Orthod 2017;87

The authors of this retrospective study evaluated the predictability of arch expansion using Invisalign. The sample included 64 white adult patients with an average age of 31.2 years, who had both arches treated by 1 practitioner using Invisalign only. The patients had no missing teeth, and their treatment entailed no interproximal reduction posterior to the distal of the canines. Twenty patients had a dentoalveolar crossbite involving at least 1 tooth, mainly premolars. The mean treatment duration was 56 weeks, and only 1 round of aligners was used; no refinement was included. Pretreatment and posttreatment digital models were obtained using an iTero scanner, which together with the patients’ Clinchecks were uploaded in Geomagic Qualify software. Using this software’s calipers, linear values of maxillary and mandibular arch widths were measured at the cusp tips and the most lingual points at the gingival margins of the canines, premolars, and first molars by the principal investigator. A paired t test was used to compare expansion planned on Clincheck with the posttreatment measurements. The results showed that when expansion is planned with Invisalign, the mean accuracy for the maxilla was 72.8%, with 82.9% at the cusp tips and 62.7% at the gingival margins. In the mandibular arch, the mean expansion was 87.7%, with 98.9% at the cusp tips and 76.4% at the gingival margins. Clincheck seems to overestimate expansion by body movement; more tipping was observed. The authors recommend overcorrection of expansion when using Invisalign, especially in the posterior region of the maxilla.

Reviewed by Nora Dolatabadi

Pharyngeal airway dimensions in children

Anandarajah S, Dudhia R, Sandlham A, Sonnesen L. Risk factors for small pharyngeal airway dimensions in preorthodontic children: a three-dimensional study. Angle Orthod 2017;87:138-46

Pharyngeal airway dimensions are associated with sleep-disordered breathing and craniofacial morphology. Thus, identifying reduced pharyngeal airway dimensions in preorthodontic children may be beneficial in planning orthodontic treatment. Because the pharyngeal airway is not regularly assessed with 3-dimensional imaging in most orthodontic offices, the aim of this study was to analyze which parameters from standard diagnostic materials are relevant to pharyngeal airway dimensions. The sample consisted of 61 girls and 44 boys with a mean age of 10.7 years. Cone-beam computed tomography images were taken with an iCAT machine, and measurements were made with Dolphin Imaging software. Upper airway dimensions that included pharyngeal airway volume and minimal cross-sectional area (MCA) were measured according to defined limits. Skeletal maturity was determined according to the cervical vertebral maturation index. The results indicated that airway volume and MCA were smaller in prepubertal children when compared with pubertal children. The authors found positive associations between airway volume and craniofacial morphology, maxillary and mandibular widths, and anterior facial height. MCA was positively associated with maxillary and mandibular width and negatively associated with sagittal jaw relationship (MCA increased with mandibular prognathism and decreased with mandibular retrognathism). The authors concluded that pharyngeal airway dimensions were associated with age, skeletal maturity, and craniofacial morphology in all 3 planes. In addition, children with reduced mandibular width and increased sagittal jaw relationship are at risk for reduced pharyngeal airway dimensions. These results are significant for orthodontic diagnosis and treatment planning, since the data suggest that children with reduced mandibular widths and mandibular retrognathism may also have compromised pharyngeal airway dimensions.

Reviewed by Ulysses Hsu

Pharyngeal airway dimensions in children

Anandarajah S, Dudhia R, Sandlham A, Sonnesen L. Risk factors for small pharyngeal airway dimensions in preorthodontic children: a three-dimensional study. Angle Orthod 2017;87:138-46

Pharyngeal airway dimensions are associated with sleep-disordered breathing and craniofacial morphology. Thus, identifying reduced pharyngeal airway dimensions in preorthodontic children may be beneficial in planning orthodontic treatment. Because the pharyngeal airway is not regularly assessed with 3-dimensional imaging in most orthodontic offices, the aim of this study was to analyze which parameters from standard diagnostic materials are relevant to pharyngeal airway dimensions. The sample consisted of 61 girls and 44 boys with a mean age of 10.7 years. Cone-beam computed tomography images were taken with an iCAT machine, and measurements were made with Dolphin Imaging software. Upper airway dimensions that included pharyngeal airway volume and minimal cross-sectional area (MCA) were measured according to defined limits. Skeletal maturity was determined according to the cervical vertebral maturation index. The results indicated that airway volume and MCA were smaller in prepubertal children when compared with pubertal children. The authors found positive associations between airway volume and craniofacial morphology, maxillary and mandibular widths, and anterior facial height. MCA was positively associated with maxillary and mandibular width and negatively associated with sagittal jaw relationship (MCA increased with mandibular prognathism and decreased with mandibular retrognathism). The authors concluded that pharyngeal airway dimensions were associated with age, skeletal maturity, and craniofacial morphology in all 3 planes. In addition, children with reduced mandibular width and increased sagittal jaw relationship are at risk for reduced pharyngeal airway dimensions. These results are significant for orthodontic diagnosis and treatment planning, since the data suggest that children with reduced mandibular widths and mandibular retrognathism may also have compromised pharyngeal airway dimensions.

Reviewed by Ulysses Hsu

Genioplasty on pharyngeal airway space

Torres HM, Vallandares-Neto J, Torres EM, Freitas RZ, Silva MA. Effect of genioplasty on the pharyngeal airway space following maxillomandibular advancment surgery. J Oral Maxillofac Surg 2017;75:189.e1-189.e12

With over 3 million cases annually, obstructive sleep apnea is a growing condition in the United States. One widely accepted procedure to increase the posterior airway space for obstructive sleep apnea patients is maxillomandibular advancement surgery. Genioplasty is often also performed to improve the profile and esthetics. Furthermore, it has been theorized that genioplasty concomitantly pulls the hyoid bone forward and decompresses the hypopharynx region; this promotes muscle changes and improves the pharyngeal airway space. The purpose of this study was to assess the effect of genioplasty on the pharyngeal airway space in adult patients without obstructive sleep apnea who were receiving maxillomandibular advancement surgery. In this study, 52 patients undergoing maxillomandibular advancement surgery were evaluated with lateral cephalometric radiographs taken before and after surgery. The pharyngeal airway space was evaluated at the nasopharynx, oropharynx, and hypopharynx in the anteroposterior dimensions. The presurgery and postsurgery cephalometric radiographs of patients with genioplasty (27) and without genioplasty (25) were compared. Changes in the horizontal and vertical dimensions of the maxilla, mandible, and chin were correlated to changes in the pharyngeal airway space. The authors observed that the patients without genioplasty had greater nasopharynx and oropharynx airway gains. However, those with genioplasty had greater increases in the hypopharynx region than did the patients without genioplasty. This study used 2-dimensional images, which is a limitation when analyzing pharyngeal airway space; the study could have been improved if 3-dimensional cone-beam images had been used. Still, these findings are useful for planning the best surgical techniques for increasing the airway in a particular pharyngeal subdivision.

Reviewed by Mona Derentz

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Dec 19, 2018 | Posted by in Orthodontics | Comments Off on Residents’ journal review
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