Evaluation of the airway space changes after extraction of four second premolars and orthodontic space closure in adult female patients with bimaxillary protrusion - A retrospective study

Three-dimensional evaluation of the airway morphology after miniscrew-supported en masse retraction in adult bimaxillary protrusion patients by using cone beam computed tomography: A single-arm clinical trial

OBJECTIVE

This study aimed to assess the changes in the pharyngeal airway morphology after premolar extraction and maximum anchorage retraction of the anterior segments in adult bimaxillary protrusion patients by using CBCT.

MATERIAL AND METHODS

Twenty-one subjects (mean age 23.8±4.6 years) requiring extraction of four first premolars and en masse retraction of the anterior segments using maximum anchorage participated in the study from July 2022 to May 2024 with an average treatment duration of 19.9 months. CBCT scans were taken before treatment (pre) and after en masse retraction (post). Airway volume was measured by using Relu software. The pre- and post-CBCT scans were superimposed by using Romexis 1 software. The cross-sectional area (CSA) was measured at the level of the hard palate, soft palate, and epiglottis. The most constricted area (MCA) was recorded. The hyoid bone position was evaluated by using 5 linear measurements. The upper and lower incisor angulations to the Frankfort horizontal plane (FH) were measured before and after retraction. Paired t-test was used to analyse the measurements and correlation analyses were made using Spearman's rank-order correlation coefficient (rs). The significance level was set at P<0.05 within all tests.

RESULTS

Twenty-one participants (16 females, 5 males) followed the inclusion criteria and enrolled in the analysis. There were no significant differences in airway volume, cross-sectional areas, or hyoid bone position between before treatment and after en masse retraction (P>0.05). There was a significant retraction of the incisors after treatment (P<0.001). The change in the most constricted area had a large positive correlation with the change in the airway volume (rs=0.509*) and the area of the soft palate (rs=0.653*).

CONCLUSION

Maximum anchorage retraction had no significant effect on airway volume, cross-sectional area, or hyoid bone position.

Orthodontic force/torque modeling and experiment of Kitchon root-controlled auxiliary archwire

The incidence of oral malocclusion is increasing and is seriously damaging the oral health of human beings. The Kitchon root-controlled auxiliary archwire is an individualized orthodontic arch. It is used clinically for the treatment of tooth-lingual tilt/root-lip tilt phenomenon of the central incisors. However, the bending parameters of the Kitchon root-controlled auxiliary archwire used in different patients are based on the clinical experience of the dentists. Therefore, this orthodontic treatment has a high risk and unpredictability. In this paper, the loading performance and orthodontic process of Kitchon root-controlled auxiliary archwire are analyzed. And the prediction model of support resistance and correction torque are established. The bending parameters of the Kitchon root-controlled auxiliary archwire, as well as the effect of the bending parameters on the support resistance and the correction torque, are all quantified. And the prediction models for the support resistance and the correction torque are calculated separately. The correlation coefficients of calculated data and experimental data are ξT1  > .97 and ξA1  > .96, respectively; the correlation coefficients of simulated data and experimental data are ξT2  > .96 and ξA2  > .96, respectively. The accuracy and reliability of the established prediction models are verified. It provides an effective theoretical guide for dentists to safely and efficiently perform root-controlled rotation orthodontic treatment on patients' central incisors.

Effect of premolar extraction and anchorage type for orthodontic space closure on upper airway dimensions and position of hyoid bone in adults: a retrospective cephalometric assessment

Background

This study aimed to assess the effect of premolar extraction and anchorage type for orthodontic space closure on upper airway dimensions and position of hyoid bone in adults by cephalometric assessment.

Methods

This retrospective study was conducted on 142 cephalograms of patients who underwent orthodontic treatment with premolar extraction in four groups of (I) 40 class I patients with bimaxillary protrusion and maximum anchorage, (II) 40 class I patients with moderate crowding and anchorage, (III) 40 class II patients with maximum anchorage, and (IV) 22 skeletal class III patients with maximum anchorage. The dimensions of the nasopharynx, velopharynx, oropharynx, and hypopharynx, and hyoid bone position were assessed on pre- and postoperative lateral cephalograms using AudaxCeph v6.1.4.3951 software. Data were analyzed by the Chi-square test, paired t-test, and Pearson's correlation test (alpha = 0.05).

Results

A significant reduction in oropharyngeal, velopharyngeal, and hypopharyngeal airway dimensions was noted in groups I, III, and IV (P < 0.001), which was correlated with the magnitude of retraction of upper and lower incisors (r = 0.6 - 0.8). In group II, a significant increase was observed in oropharyngeal and velopharyngeal dimensions (P < 0.001). A significant increase in nasopharyngeal dimensions occurred in all groups (P < 0.001). Also, in groups I and III, the position of hyoid bone changed downwards and backwards, which was correlated with reduction in airway dimensions (r = 0.4 - 0.6).

Conclusion

According to the present results, extraction orthodontic treatment affects upper airway dimensions and hyoid bone position. Maximum anchorage decreases airway dimensions while moderate anchorage increases airway dimensions.

Adaptive Changes in the Posterior Pharyngeal Wall Following Large Retraction of Incisors During Comprehensive Orthodontic Treatment

OBJECTIVE

To evaluate the effects of large retraction of incisors on the adaptive changes in the posterior pharyngeal wall and soft palate during comprehensive orthodontic treatment.

METHODS

Twenty-seven females with Class I mild crowding or spacing who required non-extraction treatment (group I) and 34 females with Class I bimaxillary dentoalveolar protrusion who required all first premolars extraction for the retraction of their incisors (group II) were included in the study. The effects of non-extraction and incisor retraction following all first premolars extraction orthodontic treatment on the sagittal dimensions of pharyngeal airway passage and posterior pharyngeal wall thickness were evaluated from pre- and post-treatment cephalograms.

RESULTS

The dimensions of pharyngeal airway passage were comparable among the groups. The length of the soft palate increased (P < .01) and the thickness of the soft palate decreased (P < .01) following retraction of incisors, and the difference between the groups was significant (P < .05). The posterior pharyngeal wall thickness was reduced significantly at PPWT2 (P < .05), PPWT3 (P < .001), PPWT4 (P < .001), PPWT5 (P < .001), and PPWT6 (P < .01) regions following retraction of the incisors, and the difference between the groups was statistically highly significant.

CONCLUSIONS

The large retraction of incisors during comprehensive orthodontic treatment in Class I bimaxillary dentoalveolar protrusion malocclusion subjects did not affect the sagittal dimensions of pharyngeal airway passage, but the thickness of the posterior pharyngeal wall reduced significantly as an adaptation to maintain the patency of the upper airway.

Oropharynx and hyoid bone changes in female extraction patients with distinct sagittal and vertical skeletal patterns: a retrospective study

Background

Previous studies have reported inconsistent effects of premolar extraction on the oropharynx and hyoid bones. Currently, no strong evidence is available regarding the effect of extraction on upper airway size. Hence, the aim of this study was to analyse the effects of first premolar extraction on the oropharynx and hyoid bone positions in female adult patients, and further explored differences in oropharynx and hyoid bone changes among skeletal patterns.

Methods

The study population included 40 female adult patients who did not undergo extraction and 120 female adult patients who underwent extraction of four premolars; the including patients had four distinct sagittal and vertical skeletal patterns. Cone-beam computed tomography was performed before (T0) and after (T1) orthodontic treatment. Eight oropharynx variables and five hyoid bone variables were measured using Dolphin 3D Imaging software. Paired and independent t-tests were used to analyse measurements between timepoints and groups, respectively.

Results

The oropharynx volume increased significantly in the extraction group; changes did not differ significantly between extraction and non-extraction groups. Oropharynx variables did not differ significantly at T0 among the four skeletal pattern groups. After orthodontic extraction treatment, the oropharynx volume increased significantly in the class I-norm and class I-hyper subgroups, but not in the class II-norm and class II-hyper subgroups. Significant increases were observed in the oropharynx volume and most constricted axial area from T0 to T1 in the moderate retraction group, but not in the maximum retraction group. Extraction patients exhibited significant posterior movement of the hyoid, particularly among maximum retraction patients.

Conclusions

In female adult patients, first premolar extraction tends to increase the oropharynx size and cause posterior movement of the hyoid bone, particularly in skeletal class I patients. For skeletal class II and hyperdivergent patients with a narrow oropharynx, first premolar extraction does not negatively influence oropharynx size or hyoid bone position. The differences of oropharyngeal changes between moderate retraction patients and maximum retraction patients were not significant.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13005-022-00334-1.

Mobile application for monitoring and normalizing the mastication muscle functional condition

Relevance. We have developed and patented a mobile application for monitoring and normalizing the mastication muscle functional state to solve the problems of detecting people with suspected dysfunction of the jaw muscles and increase the efficiency of muscle exercises.

Purpose. To evaluate the positive effect of the mobile application to control and normalize the mastication muscle functional state in the clinical orthodontic practice.

Material and methods. The study included 74 patients of Children Clinical Dental Clinic No. 2 of Voronezh, aged 6 to 12 years, who presented for a dental check-up. The masseter muscle tone was determined using the Mioton-3S device.

Results. The authors’ method of self-examination does not give a systematic overestimation or underestimation of parameters (p = 0.083) compared to the standard myotonometry, which evidences its reliability and the possibility to use for preliminary examination and detection of people with suspected abnormal muscle tone. The analysis of the masseter muscles’ tone one month later revealed a statistically signifcant (p = 0.034) decrease in the number of patients with tone disorder among the mobile application users compared to the patients who did not use the application.

Conclusion. The developed mobile application is efficient for preliminary assessment and detection of people with suspected abnormal muscle tone. Mobile application helps increase efficiency and awareness of muscle exercises.

Maxillofacial trauma in the gulf countries: a systematic review

PURPOSE

The objective of this review was to determine the prevalence, major causative factors and the most common sites of Maxillofacial Trauma in the Gulf Cooperation Council (GCC) Countries.

METHODS

All articles that were published in the English language in the databases such as Google Scholar, EBSCO, PubMed, NCBI, Medline, COCHRANE, ELSEVIER and SCOPUS were reviewed for MFT from GCC during the last 23 years.

RESULTS

A total of 19,151 patients (16,567 males and 2584 females) (86-14%) with an age range between 0 and 97 years were included in the study. In all of the Gulf countries males outnumber females in terms of maxillofacial injuries with a ratio of 6.4:1. The mandible was the most common site of trauma followed by the maxilla. Road Traffic Accidents (RTA) was the most common cause of injury in the GCC followed by falls.

CONCLUSION

Maxillofacial injuries are highly prevalent, distributed among the Gulf countries, and is mainly caused by RTAs especially among males who are highly prone to MFT in the gulf. The reasons are due to lack of road safety culture and weak enactment of traffic legislation, other possible factors include intrinsic car safety features, high speed driving and the amount/use of highways in these societies.

Orthodontic force prediction model of T-loop closing spring based on dynamic resistance model

Malocclusion has been seriously endangering human oral function. The most effective and mature therapy is orthodontic treatment. But the relationship between the shape of the T-loop and the orthodontic force is unclear, and the precise mathematical model has not been established. In this article, the dynamic orthodontic force prediction model of the T-loop was established by analyzing the treatment process of the T-loop. The model was based on the dynamic resistance model of waxy dental jaw, the theory of beam deformation, and the deformation characteristics of the T-loop. In the experimental process, 11 kinds of orthodontic archwires were used as experimental samples, including 2 kinds of common archwire materials, 7 kinds of cross-sectional sizes, and 10 kinds of clearance distances. The T-loop was put into the extraction space and immersed in 75°C constant temperature water for 2 min. And the experimental data were measured and collected by the dynamic force measuring device. The experimental results show that the cross-sectional size and the clearance distance are positively correlated with the orthodontic force. The influence of the clearance distance on the orthodontic force is greater than that of the cross-section size. The deviation rates between the experimental values of orthodontic force and the theoretical values are between 1.10% and 9.09%, which verifies the accuracy of the dynamic orthodontic force prediction model. The model can predict the orthodontic force, improve the treatment effect, shorten the treatment cycle, and provide reference and guidance for orthodontists to carry out orthodontic treatment safely and effectively.