Changes in mandibular position and upper airway dimension by wearing cervical headgear during sleep

Evaluation of Hyoid Position and Retroglossal Airway After Mandibular Alveolar Archwise Distraction Osteogenesis

The interaction between form and function in the craniofacial region is a well-accepted fact in orthodontics. The aim of the present study is to objectively evaluate if mandibular sagittal symphyseal distraction causes an increase in the retroglossal airway size and hyoid position in a retrospective clinical study. The pretreatment (T0) and 3 months post-distraction (T1) cone-beam computed tomography images of 12 patients (mean age 17.1 years) were retrieved. The retroglossal airway volume and hyoid-mandibular plane distance, hyoid-C3 distance, sella-nasion-B point angle angle, lower incisor to mandibular plane, and Mandibular plane angles were measured using 3D medical imaging software. The average amount of distraction at the superior border of the bony transport segment was 6.2 mm and 4.4 mm at the inferior border. The changes in retroglossal airway volume (2943.2 mm), incisor to mandibular plane (6.5°), and mandibular plane (2.1°) were significant. The changes in hyoid-mandibular plane distance and hyoid-C3 distances were not significant. However, a downward repositioning in Hyoid position was observed along with the mandibular clockwise rotation. This study showed that symphyseal dentoalveolar distraction osteogenesis, as a complementary to orthodontic therapy, can affect the form and size of the pharynx. Therefore, the airway size should be one of the diagnostic and decisive factors for an ideal treatment planning.

Efficacy of the Addition of a Cervical Collar in the Treatment of Persistent Obstructive Apneas Despite Continuous Positive Airway Pressure

ABSTRACT

Continuous positive airway pressure (CPAP) is currently the reference treatment for obstructive sleep apnea (OSA). The use of a face mask, although sometimes necessary, is often associated with increased airway obstruction due to mandibular retrusion. We report a small group of patients in whom addition of a cervical collar to a face mask allowed correction of obstructive events.

How has our interest in the airway changed over 100 years?

Since the beginning of our specialty, our understanding of the link between function and facial growth and development has progressively improved. Today, we know that children with sleep-related breathing problems will often develop distinctive facial characteristics. In adults, sleep apnea can result in serious morbidity and mortality. Orthodontists can ask sleep-related questions in the health history to help identify sleep breathing disorders. Treating these patients presents unique opportunities for orthodontists to collaborate with other medical specialties to improve a patient's health and treatment outcome. Research presented in our Journal in the next century may shed new light that will help us better identify the problem and aid the specialty in developing more effective evidence-based treatment. Additional efforts are needed to understand the physiology, neurology, and genetics of sleep breathing disorders.

Upper Airway Changes after Orthodontic Extraction Treatment in Adults: A Preliminary Study using Cone Beam Computed Tomography

OBJECTIVE

Whether the orthodontic treatment with premolar extraction and maximum anchorage in adults will lead to a narrowed upper airway remains under debated. The study aims to investigate the airway changes after orthodontic extraction treatment in adult patients with Class II and hyperdivergent skeletal malocclusion.

MATERIALS AND METHODS

This retrospective study enrolled 18 adults with Class II and hyperdivergent skeletal malocclusion (5 males and 13 females, 24.1 ± 3.8 years of age, BMI 20.33 ± 1.77 kg/m2). And 18 untreated controls were matched 1:1 with the treated patients for age, sex, BMI, and skeletal pattern. CBCT images before and after treatment were obtained. DOLPHIN 11.7 software was used to reconstruct and measure the airway size, hyoid position, and craniofacial structures. Changes in the airway and craniofacial parameters from pre to post treatment were assessed by Wilcoxon signed rank test. Mann-Whitney U test was used in comparisons of the airway parameters between the treated patients and the untreated controls. Significant level was set at 0.05.

RESULTS

The upper and lower incisors retracted 7.87 mm and 6.10 mm based on the measurement of U1-VRL and L1-VRL (P < 0.01), while the positions of the upper and lower molars (U6-VRL, and L6-VRL) remained stable. Volume, height, and cross-sectional area of the airway were not significantly changed after treatment, while the sagittal dimensions of SPP-SPPW, U-MPW, PAS, and V-LPW were significantly decreased (P < 0.05), and the morphology of the cross sections passing through SPP-SPPW, U-MPW, PAS, and V-LPW became anteroposteriorly compressed (P <0.001). No significant differences in the airway volume, height, and cross-sectional area were found between the treated patients and untreated controls.

CONCLUSIONS

The airway changes after orthodontic treatment with premolar extraction and maximum anchorage in adults are mainly morphological changes with anteroposterior dimension compressed in airway cross sections, rather than a decrease in size.

Uvulo-glossopharyngeal dimensions in non-extraction, extraction with minimum anchorage, and extraction with maximum anchorage

The aim of this study was to investigate upper respiratory airway dimensions in non-extraction and extraction subjects treated with minimum or maximum anchorage. Lateral cephalograms of 39 Class I subjects were divided into three groups (each containing 11 females and 2 males) according to treatment procedure: group 1, 13 patients treated with extraction of four premolars and minimum anchorage; group 2, 13 cases treated non-extraction with air-rotor stripping (ARS); and group 3, 13 bimaxillary protrusion subjects treated with extraction of four premolars and maximum anchorage. The mean ages of the patients were 18.1 ± 3.7, 17.8 ± 2.4, and 15.5 ± 0.88 years, respectively. Tongue, soft palate, hyoid position, and upper airway measurements were made on pre- and post-treatment lateral cephalograms and the differences between the mean measurements were tested using Wilcoxon signed-ranks test. Superior and middle airway space increased significantly (P < 0.05) in group 1. In group 2, none of the parameters showed a significant change, while in group 3, middle and inferior airway space decreased (P < 0.01). The findings show that extraction treatment using maximum anchorage has a reducing effect on the middle and inferior airway dimensions.

Maxillary Protraction Appliance Effect on the Size of the Upper Airway Passage

Objective: To test the hypothesis that maxillary protraction appliances (MPA) have no effect on the size of the upper airway passage and craniofacial structures in adolescent patients.

Materials and Methods: Twenty patients (5 male and 15 female; mean age 11.5 years) with skeletal Class III malocclusion were included in this study. The records of all patients who had maxillary protraction treatment and had lateral head radiographs taken before and after their protraction treatments were obtained from the files of treated cases. Treatment changes were determined by means of linear, angular, and area measurements. Data were analyzed statistically by means of paired t-test and correlation analysis.

Results: Significant increases were observed in the width and area of the pharyngeal airway. Significant increases also occurred in the sagittal growth of the maxilla, while a clockwise rotation and inhibition of sagittal growth were observed in the mandible.

Conclusions: The hypothesis was rejected. The size of the upper airway can be increased by means of MPA application.

Cervical Headgear Effects on the Morphology of the Cervical Vertebrae and Cervical Posture

OBJECTIVE

To test the hypothesis that use of cervical headgear has an important effect on the morphology of the cervical vertebrae and cervical posture.

MATERIALS AND METHODS

The material consisted of pretreatment and posttreatment lateral cephalograms and initial hand-wrist films of 30 subjects who were receiving cervical headgear therapy. Preobservation and postobservation control cephalograms and preobservation hand-wrist films of 15 untreated subjects served as controls. The average treatment time for the treatment group was 9.06 +/- 1.02 months, and the average observation period for the control group was 10.0 +/- 1.1 months. A paired t-test was applied to compare the changes occurring during the examination and observation periods in both groups. In addition, Student's t-test was performed to assess the differences between the groups.

RESULTS

The results of the paired t-test showed that within each group there were statistically significant differences in the majority of measurements concerning the morphology of the cervical vertebrae, whereas the measurements concerning cervical posture showed no significant changes in either group. According to the results of the Student's t-test, however, no statistically significant changes between the treatment and control group were present except with regard to two measurements.

CONCLUSIONS

Changes in the cervicovertebral morphology in the treatment group were achieved more by growth than by cervical headgear treatment. Although high individual variations were found in postural variables, cervical posture did not change over a period of 9 months either in the treatment group or in the control group.

Effect of cervical headgear wear on dynamic measurement of head position

The aim of this study was to identify the effect of cervical headgear (CHG) wear on dynamic measurement of head posture during walking. Six male and 10 female patients (mean age, 11.9 +/- 1.9 years) who were receiving CHG therapy for correction of a Class II molar relationship as part of their orthodontic treatment were included in this study. Dynamic head posture measurements were recorded using an inclinometer and data logger apparatus during a walking session of 5 minutes. This procedure was repeated before (T1) and after (T2) insertion of CHG. The T1 and T2 measurements were repeated twice at 30-minute intervals. The mean dynamic head posture was calculated for each subject using the collected data. The means of these measurements were statistically compared using a paired t-test. Of the 16 subjects, 14 showed a cranial flexion with CHG wear in relation to T1 (1.4 to 8.9 degrees). The other two subjects showed a cranial extension of -1.6 and -3.8 degrees. The mean values at T1, T2 and T1-T2 were 1.4, -1.8, and 3.1 degrees, respectively, which indicated a mean cranial flexion at T2 in relation to T1. According to the paired sample t-test, there were statistically significant differences between the two measurements of dynamic head posture recorded before and after CHG insertion (P < 0.001). CHG wear causes a significant cranial flexion which may be responsible for its effects on the mandible.

Effects of maxillary distraction osteogenesis on the upper-airway size and nasal resistance in subjects with cleft lip and palate

OBJECTIVES

To investigate the short- and long-term effects of maxillary distraction osteogenesis (DOG) on the upper-airway size and nasal resistance in nine patients with cleft lip and palate (CLP).

STUDY DESIGN

Changes in the upper-airway size were measured by using lateral cephalometric radiographs taken immediately before and after DOG, and 1 year later. Nasal resistance was measured with a rhinomanometer. An analysis of variance was used to establish statistical significance. Spearman correlation coefficient was used to evaluate the relationship between changes in the cross-sectional area of the upper airway and nasal resistance in association with DOG.

RESULTS

Immediately after DOG, the anteroposterior dimension of the superior part of the upper airway was significantly increased (p < 0.01) and nasal resistance was significantly decreased (p < 0.05). Moreover, the cross-sectional area of the total upper airway was significantly increased (p < 0.01). There was a significant correlation between the increase in the upper-airway cross-sectional area and the reduction in nasal resistance (p < 0.05). The upper-airway size was significantly augmented (p < 0.05) and nasal resistance was significantly reduced (p < 0.05) at 1 year after DOG compared with immediately before DOG.

CONCLUSION

An increase in the upper-airway size and a reduction in nasal resistance occurred after maxillary DOG in patients with CLP, and these changes were stable after 1 year.

Lack of efficacy for a cervicomandibular support collar in the management of obstructive sleep apnea

STUDY OBJECTIVES

The effect of therapy using a cervicomandibular support collar (CMSC) to manage obstructive sleep apnea (OSA) was compared with standard therapy, nasal continuous positive airway pressure (nCPAP).

DESIGN

Subjects received treatment with CMSC or nCPAP each for 1 month in random order. The study was analyzed on an intention-to-treat basis.

SETTING

Tom McKendrick Sleep Laboratory, Dunedin Hospital.

PARTICIPANTS

Ten adult subjects with mild-to-moderate OSA (apnea-hypopnea index [AHI], 24 +/- 13/h slept [mean +/- SD]) completed the study.

INTERVENTIONS

The CMSC was designed to prevent mandibular movement and hold the head in slight extension, thus preventing the postural changes that might contribute to OSA. Positioning of the CMSC was confirmed by an externally applied cervical range of motion (CROM) instrument and by cephalometry. Subjects were carefully instructed in the use of each device and completed a symptom diary. After 1 month, subjects underwent polysomnography with each of the allocated devices in situ, and symptom questionnaires were administered.

MEASUREMENTS AND RESULTS

Treatment success (AHI </= 10/h slept) with CMSC was achieved in only 2 of 10 subjects, partial success (AHI > 10/h to </= 15/h slept) was achieved in 2 subjects, and in 6 of 10 subjects there was no benefit. In contrast, treatment success was achieved in 7 of 10 subjects receiving nCPAP. Mean AHI was 29.4 +/- 13.4/h at baseline, 26.9 +/- 17.2/h slept with CMSC, and 9.9 +/- 8.0/h slept with nCPAP (p = 0.001). No significant differences in sleep architecture or sleep efficiency were achieved using nCPAP compared to CMSC. The efficacy of the CMSC in maintaining the desired head position was confirmed by cephalometry and the CROM instrument.

CONCLUSIONS

Our results, although negative, provide important evidence that control of head and neck posture, perhaps adopted as a second-line treatment, is not helpful in the management of OSA. It appears that other anatomic and physiologic factors have a dynamic overriding influence on upper airway closure compared to simple skeletal relationships.

Distal molar movement with Kloehn headgear: is it stable?

The aim of this study was to evaluate intramaxillary molar movement after 8 months of cervical traction and posttreatment displacement 7 years later. The total molar displacements in relation to stable intraosseous reference points were compared with those observed in an untreated control group that also had intraosseous reference indicators inserted. During the headgear period, the type of molar displacement could be predicted by the direction of the force system acting on the teeth. It was noted, however, that the variation in the vertical development was related more to each patient's growth pattern than to the force system applied. After cessation of the headgear, intramaxillary displacement of the molars was noted, and the total displacement of the molars did not differ from that of the untreated group. The indication for intramaxillary displacement of the molars by means of extraoral traction is therefore questioned.