Surgically Assisted Rapid Palatal Expansion to Correct Maxillary Transverse Deficiency

Prediction of midpalatal suture maturation stage based on transfer learning and enhanced vision transformer

BACKGROUND

Maxillary expansion is an important treatment method for maxillary transverse hypoplasia. Different methods of maxillary expansion should be carried out depending on the midpalatal suture maturation levels, and the diagnosis was validated by palatal plane cone beam computed tomography (CBCT) images by orthodontists, while such a method suffered from low efficiency and strong subjectivity. This study develops and evaluates an enhanced vision transformer (ViT) to automatically classify CBCT images of midpalatal sutures with different maturation stages.

METHODS

In recent years, the use of convolutional neural network (CNN) to classify images of midpalatal suture with different maturation stages has brought positive significance to the decision of the clinical maxillary expansion method. However, CNN cannot adequately learn the long-distance dependencies between images and features, which are also required for global recognition of midpalatal suture CBCT images. The Self-Attention of ViT has the function of capturing the relationship between long-distance pixels of the image. However, it lacks the inductive bias of CNN and needs more data training. To solve this problem, a CNN-enhanced ViT model based on transfer learning is proposed to classify midpalatal suture CBCT images. In this study, 2518 CBCT images of the palate plane are collected, and the images are divided into 1259 images as the training set, 506 images as the verification set, and 753 images as the test set. After the training set image preprocessing, the CNN-enhanced ViT model is trained and adjusted, and the generalization ability of the model is tested on the test set.

RESULTS

The classification accuracy of our proposed ViT model is 95.75%, and its Macro-averaging Area under the receiver operating characteristic Curve (AUC) and Micro-averaging AUC are 97.89% and 98.36% respectively on our data test set. The classification accuracy of the best performing CNN model EfficientnetV2_S was 93.76% on our data test set. The classification accuracy of the clinician is 89.10% on our data test set.

CONCLUSIONS

The experimental results show that this method can effectively complete CBCT images classification of midpalatal suture maturation stages, and the performance is better than a clinician. Therefore, the model can provide a valuable reference for orthodontists and assist them in making correct a diagnosis.

Skeletal and dental effects of function-generating bite appliance compared to rapid palatal expander and untreated controls

INTRODUCTION

Maxillary expansion is a fundamental interceptive orthodontic treatment, which can be achieved through either a rapid expansion protocol or functional devices. However, no data exist about the efficacy of functional devices in achieving skeletal expansion. Therefore, the aim of this study was to compare the effects of the rapid palatal expander (RPE) and the function-generating bite type M (FGB-M) on the transversal dimension of the maxilla, and on the maxillary and mandibular dental arch width.

METHODS

One hundred eighty-one skeletal Class I patients, aged between 6 and 12 years and with a cervical vertebral maturation stage II or III, with maxillary transversal deficiency were retrospectively enrolled; among these 55 were treated with FGB-M, 73 were treated with RPE and 51 were untreated subjects retrieved from historical databases. The pre-treatment (T0) and post-treatment (T1) frontal cephalograms were retrieved, and the maxillary and mandibular widths, and the distance between upper and lower first molars were measured. T1-T0 interval was of 17.3 months (RPE), 24.6 months (FGB-M) and 18.2 months (controls).

RESULTS

The statistical analysis showed that there were no statistically significant differences between the RPE and FGB-M groups regarding skeletal and dental expansion, while the untreated control group differed significantly from the other two groups.

CONCLUSION

The comparison between patients treated with RPE and FGB-M showed that there were no statistically significant differences between the RPE and FGB-M groups regarding the amount of skeletal expansion and dental arch width, suggesting that both appliances can be used to achieve similar results.

Sagittal and Vertical Changes of the Maxilla after Surgically Assisted Rapid Palatal Expansion: A Systematic Review and Meta-Analysis

Surgically assisted rapid palatal expansion (SARPE) is often performed to correct the transverse deficiency in the maxilla for skeletally mature patients. However, there is little consensus on the sagittal and vertical displacement of the maxilla after SARPE. This systematic review aims to analyze the position changes of the maxilla in the sagittal and vertical dimensions after the completion of SARPE. Registered with PROSPERO (registration number: CRD42022312103), this study complied with the 2020 PRISMA guideline and was conducted on 21 January 2023. Original studies were screened from MEDLINE (PubMed), Elsevier (SCOPUS), and Cochrane, and supplemented by hand-searching. Cephalometric changes of skeletal vertical and sagittal measurements were the focus. A fixed-effects model was applied in R for meta-analysis. After applying inclusion and exclusion criteria, seven articles were included in the final review. Four studies had a high risk of bias, and the other three had a medium risk of bias. Meta-analysis revealed that the SNA angle increased by 0.50° ± 0.08° (95% confidence interval, 0.33° to 0.66°), and the SN-PP angle increased by 0.60° ± 0.09° (95% confidence interval, 0.41° to 0.79°) after SARPE. In summary, the maxilla displayed statistically significant forward and clockwise downward movement after SARPE. However, the amounts were small and might not be clinically significant. Due to the high risk of bias of included studies, our results must be taken cautiously. Future studies are needed to discern the effects of direction and angulation of the osteotomies of SARPE on the displacement of the maxilla.

Maxillary transverse deficiency, with closed intermaxillary suture, does bone-anchored appliance during SARPE cause predictable, and stable maxillary expansion compared to the tooth-borne appliance during SARPE - Systematic review

INTRODUCTION

Managing maxillary transverse deficiency (MTD) with closed intermaxillary suture is a challenge in orthodontic treatment plans; over the years, clinicians have developed many approaches to treat this significant dentofacial deformity. Therefore, it is crucial to understand the underlying causes of MTD and to establish an effective treatment method for restoring the ideal aesthetics and functions for patients. A current and effective SARPE technique for expanding the maxillary arch involves performing 2-piece Le Fort I osteotomy to surgically apply horizontal force to the maxilla along the midpalatal suture in conjunction with either a tooth-borne or bone-borne appliance.

MATERIAL AND METHODS

A systemic review was conducted in order to investigate the differences between the two treatment methods for MTD with matured and closed intermaxillary suture: bone-anchored and tooth-borne appliance during SARPE (surgically-assisted rapid palatal expansion). The review was conducted in the English language through PubMed and Google Scholar electronic databases. The protocol is being reported in accordance with the PRISMA Statement.

RESULTS

This research, however, is subject to several limitations, including minimal randomization, limited sample size, indefinite measurement methods, and a short follow-up period. Each method of maxillary transverse deficiency therapy has been proven to be effective in expanding the maxillary arch.

CONCLUSION

From the analysis of the articles, it was concluded that bone-anchored appliances have a more predictable and stable expansion compared to the tooth-borne appliance during SARPE. Nevertheless, further studies are needed to confirm its long-term effectiveness.

Displacement and stress distribution of the craniomaxillofacial complex under different surgical conditions: a three-dimensional finite element analysis of fracture mechanics

Objective

To provide a simplified treatment strategy for patients with maxillary transverse deficiency. We investigated and compared the fracture mechanics and stress distribution of a midline palatal suture under dynamic loads during surgically-assisted rapid palatal expansion.

Methods

Based on the cone-beam computed tomography (CBCT) data of a 21-year-old female volunteer, a three-dimensional model of the cranio-maxillofacial complex (including the palatal suture) was constructed. A finite element analysis model was constructed based on meshwork. After the yield strength of the palatal suture was set, an increasing expansion force (0–500 N) was applied within 140 ms to calculate the time–load curve, which mimicked nonsurgical bone expansion (model A). The same method was used to evaluate the fracture process, time and stress distribution of the palatal suture in maxillary lateral osteotomy-assisted (model B) and LeFort osteomy I (LFIO)-assisted expansion of the maxillary arch (model C).

Results

Compared with model A, the palatal suture of model B and model C showed a faster stress accumulation rate and shorter fracture time, and the fracture time of model B and model C was almost identical. Compared with model A, we discovered that model B and model C showed greater lateral extension of the maxilla, and the difference was reflected mainly in the lower part of the maxilla, and there was no difference between model B and model C in lateral extension of the maxilla.

Conclusions

Compared with arch expansion using nonsurgical assistance (model A), arch expansion using maxillary lateral wall-osteotomy (model B) or LFIO had a faster rate of stress accumulation, shorter time of fracture of the palatal suture and increased lateral displacement of the maxilla. Compared with arch expansion using LFIO (model C), arch expansion using lateral osteotomy (model B) had a similar duration of palatal suture rupture and lateral maxillary extension. In view of the trauma and serious complications associated with LFIO, maxillary lateral wall-osteotomy could be considered a substitute for LFIO.