Association between orthodontic treatment and upper airway changes in children assessed with cone-beam computed tomography (CBCT): A systematic review.

BACKGROUND: Some orthodontic devices used in children share similar design principles to appliances used to treat obstructive sleep apnoea in adults. As well as treating malocclusion, orthodontic appliances used in children may therefore also have effects on the upper airway. OBJECTIVE: A review of the literature to assess the effects of orthodontic treatment on the upper airway dimensions in children assessed on CBCT. MATERIALS AND METHODS: Following registration of the protocol (PROSPERO CRD42023439056), a systematic electronic search of published studies was performed using several databases (PubMed; Scopus, Web of Science and Science Direct) in accordance with the PRISMA guidelines. Inclusion criteria were as follows: age under 18 years, orthodontic treatment with any appliance, a control group who received no treatment or a non-active alternative treatment and airway measurement using CBCT. RoB-2 and ROBINS-I tools were used to assess risk of bias and quality of the evidence. RESULTS: In total, 341 studies were identified following the initial search. Title and abstract screening resulted in 45 studies for further full-text analysis. On completion of the screening process, a total of 23 studies met the inclusion criteria. Study interventions included functional appliances (10 studies), rapid maxillary expansion (RME) (9 studies), reverse-pull headgear (1 study) and 4 premolar dental extractions (3 studies). The included studies had moderate to high risk of bias, and the quality of evidence was low. CONCLUSION: The scientific evidence shows that functional appliances are associated with significant improvements in both upper airway volume and constriction when used in children however, the effects on the nasal cavity are limited. RME was associated with a significant increase in nasal cavity and nasopharyngeal dimensions, but not the upper pharyngeal airway. Neither reverse-pull headgear nor dental extractions were associated with any change in airway dimensions; however, the evidence is limited. Functional appliances may reduce the severity of obstructive sleep apnoea (OSA) in children.

Airway changes after fixed functional appliance treatment in children with and without morphologic deviations of the upper spine: A 3-dimensional CBCT study.

INTRODUCTION: Functional appliances (FA) have a positive effect on the upper airway volume and minimal cross-sectional area (MCA) in children. An association between morphologic deviations of the upper spine (MDUS) and reduced treatment response was found in appliances used to treat adults with obstructive sleep apnea. This study aimed to: (1) compare airway changes after FA treatment in children with and without MDUS and controls; (2) identify if MDUS causes a smaller upper airway. METHODS: Pretreatment and posttreatment cone-beam computed tomography scans were included from 21 children with MDUS and 42 without MDUS treated with a fixed FA, along with a pair-matched control group (matched for chronological age, skeletal age, gender, and mandibular inclination) who received orthodontic treatment for minor malocclusions without an FA. The influence of MDUS on changes in upper airway volume and MCA were evaluated with 3-dimensional cone-beam computed tomography scans using standardized, previously validated methods and mixed-effects linear regression. RESULTS: There was a significantly increased volume and MCA in the FA groups with and without MDUS compared with control (P = 0.003 and P = 0.049) and in the FA group without MDUS compared with the MDUS group (P = 0.008 and P = 0.011) after treatment. There was no significant pretreatment difference in airway dimensions between the MDUS and non-MDUS FA groups. CONCLUSIONS: The airway response with fixed FA is significantly reduced in MDUS children. MDUS caused no significant pretreatment airway differences in children. However, MDUS may be important in predicting airway changes in FA treatment.

Effects of a fixed functional appliance on upper airway volume: A 3-dimensional cone-beam computed tomography study.

INTRODUCTION: Although functional appliances (FAs) are primarily used to treat Class II malocclusions, their effects on the upper airway have generally been reported in studies involving 2-dimensional analysis of cephalometric radiographs. This study aimed to use 3-dimensional cone-beam computed tomography to (1) determine the effects on upper airway volume and minimum cross-sectional area (MCA) when an FA is used for orthodontic treatment and (2) identify pretreatment markers for airway changes. METHODS: Pre- and posttreatment cone-beam computed tomography scans were selected from 73 children whose orthodontic treatment involved using a fixed FA (37 girls and 36 boys; mean age 12.0 years); a control group was constituted and included the scans of 73 children who were matched for chronological age, skeletal age, sex, and mandibular inclination and who received orthodontic treatment for minor malocclusions without an FA. Changes in upper airway volume and MCA were evaluated by a standardized, previously validated method analyzed with mixed-effects linear regression. RESULTS: Upper airway volume and MCA increased over time for both the FA and the matched control groups (P <0.05). The FA caused an additional significant increase in upper airway volume and MCA (P <0.0001) when compared with the control group. An increased ANB angle, a reduced mandibular inclination, and a reduced skeletal age pretreatment had a positive effect on upper airway volume and MCA (P <0.05). CONCLUSIONS: A fixed FA was associated with a significant increase in upper airway volume and MCA in children when compared with controls. Pretreatment ANB angle, skeletal age, and mandibular inclination may be predictors for positive changes in the upper airway. The results may prove valuable in treating children with Class II malocclusions with compromised upper airways.

A high density SLAF-SNP genetic map and QTL detection for fibre quality traits in Gossypium hirsutum.

BACKGROUND: Upland Cotton (Gossypium hirsutum) is a very important cash crop known for its high quality natural fiber. Recent advances in sequencing technologies provide powerful tools with which to explore the cotton genome for single nucleotide polymorphism marker identification and high density genetic map construction toward more reliable quantitative trait locus mapping. RESULTS: In the present study, a RIL population was developed by crossing a Chinese high fiber quality cultivar (Yumian 1) and an American high fiber quality line (CA3084), with distinct genetic backgrounds. Specific locus amplified fragment sequencing (SLAF-seq) technology was used to discover SNPs, and a genetic map containing 6254 SNPs was constructed, covering 3141.72 cM with an average distance of 0.5 cM between markers. A total of 95 QTL were detected for fiber quality traits in three environments, explaining 5.5-24.6% of the phenotypic variance. Fifty-five QTL found in multiple environments were considered stable QTL. Nine of the stable QTL were found in all three environments. We identified 14 QTL clusters on 13 chromosomes, each containing one or more stable QTL. CONCLUSION: A high-density genetic map of Gossypium hirsutum developed by using specific locus amplified fragment sequencing technology provides detailed mapping of fiber quality QTL, and identification of 'stable QTL' found in multiple environments. A marker-rich genetic map provides a foundation for fine mapping, candidate gene identification and marker-assisted selection of favorable alleles at stable QTL in breeding programs.

Effects of rapid maxillary expansion on upper airway volume: A three-dimensional cone-beam computed tomography study.

OBJECTIVE: To compare changes in pharyngeal airway volume and minimal cross-sectional area (MCA) between patients undergoing rapid maxillary expansion (RME) and a matched control group and to identify markers for predicting airway changes using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Pre- and posttreatment CBCT scans were selected of children who had RME (14 girls and 12 boys; mean age, 12.4 years) along with scans of a control group (matched for chronological age, skeletal age, gender, mandibular inclination) who underwent orthodontic treatment for minor malocclusions without RME. Changes in airway volume and MCA were evaluated using a standardized, previously validated method and analyzed by a mixed-effects linear regression model. RESULTS: Upper airway volume and MCA increased significantly over time for both the RME and matched control groups (P < .01 and P = .05, respectively). Although the RME group showed a greater increase when compared with the matched controls, this difference was not statistically significant. A reduced skeletal age before treatment was a significant marker for a positive effect on the upper airway volume and MCA changes (P < .01). CONCLUSIONS: Tooth-borne RME is not associated with a significant change in upper airway volume or MCA in children when compared with controls. The younger the skeletal age before treatment, the more positive the effect on the upper airway changes. The results may prove valuable, especially in RME of young children.