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Chin J Traumatol
Chin J Traumatol
Chinese Journal of Traumatology
1008-1275
1008-1275
Elsevier

S1008-1275(24)00030-0
10.1016/j.cjtee.2024.03.004
Original Article
A retrospective study of occlusal reconstruction in patients with old jaw fractures and dentition defects
Ding Ming-Chao a
Jing Bo-Ya b
Shi Jin a
Yang Liu a
Liu Xiang-Dong a
Wang Jing-Fu a
Qu Shuang c
Liang Jia-Wu b
Tang Zi-Hao a
Zhao Jin-Long b⁎⁎
Tian Lei tianleison@163.com
a⁎
a State Key Laboratory of Oral and Maxillofacial Reconstruction and Regeneration, National Clinical Research Center for Oral Diseases, Shaanxi Clinical Research Center for Oral Diseases, Department of Oral and Maxillofacial, School of Stomatology, The Fourth Military Medical University, Xi'an, 710032, China
b Department of Maxillofacial Trauma and Orthognathic Surgery, The Third Affiliated Hospital, The Air Force Military Medical University, Xi'an, 710038, China
c Department of Stomatology, 941th Hospital of People's Liberation Army Joint Logistic Support Force, Xining, 810000, China
⁎ Corresponding author. tianleison@163.com
⁎⁎ Corresponding author.
11 3 2024
9 2024
11 3 2024
27 5 272278
21 11 2023
28 12 2023
2 2 2024
© 2024 Chinese Medical Association. Production and hosting by Elsevier B.V.
2024
Chinese Medical Association
https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Purpose

This study evaluated the methods and clinical effects of multidisciplinary collaborative treatment for occlusal reconstruction in patients with old jaw fractures and dentition defects.

Methods

Patients with old jaw fractures and dentition defects who underwent occlusal reconstruction at the Third Affiliated Hospital of Air Force Military Medical University from January 2018 to December 2022 were enrolled. Clinical treatment was classified into 3 phases. In phase I, techniques such as orthognathic surgery, microsurgery, and distraction osteogenesis were employed to reconstruct the correct 3-dimensional (3D) jaw position relationship. In phase II, bone augmentation and soft tissue management techniques were utilized to address insufficient alveolar bone mass and poor gingival soft tissue conditions. In phase III, implant-supported overdentures or fixed dentures were used for occlusal reconstruction. A summary of treatment methods, clinical efficacy evaluation, comparative analysis of imageological examinations, and satisfaction questionnaire survey were utilized to evaluate the therapeutic efficacy in patients with traumatic old jaw fractures and dentition defects. All data are summarized using the arithmetic mean ± standard deviation and compared using independent sample t-tests.

Results

In 15 patients with old jaw fractures and dentition defects (an average age of 32 years, ranging from 18 to 53 years), there were 7 cases of malocclusion of single maxillary fracture, 6 of malocclusion of single mandible fracture, and 2 of malocclusion of both maxillary and mandible fractures. There were 5 patients with single maxillary dentition defects, 2 with single mandibular dentition defects, and 8 with both maxillary and mandibular dentition defects. To reconstruct the correct 3D jaw positional relationship, 5 patients underwent Le Fort I osteotomy of the maxilla, 3 underwent bilateral sagittal split ramus osteotomy of the mandible, 4 underwent open reduction and internal fixation for old jaw fractures, 3 underwent temporomandibular joint surgery, and 4 underwent distraction osteogenesis. All patients underwent jawbone augmentation, of whom 4 patients underwent a free composite vascularized bone flap (26.66%) and the remaining patients underwent local alveolar bone augmentation. Free gingival graft and connective tissue graft were the main methods for soft tissue augmentation (73.33%).

The 15 patients received 81 implants, of whom 11 patients received implant-supported fixed dentures and 4 received implant-supported removable dentures. The survival rate of all implants was 93.82%. The final imageological examination of 15 patients confirmed that the malocclusion was corrected, and the clinical treatment ultimately achieved occlusal function reconstruction. The patient satisfaction questionnaire survey showed that they were satisfied with the efficacy, phonetics, aesthetics, and comfort after treatment.

Conclusion

Occlusal reconstruction of old jaw fractures and dentition defects requires a phased sequential comprehensive treatment, consisting of 3D spatial jaw correction, alveolar bone augmentation and soft tissue augmentation, and implant-supported occlusal reconstruction, achieving satisfactory clinical therapeutic efficacy.

Keywords

Old jaw fractures
Malocclusion
Occlusal reconstruction
Dental implant prosthesis
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pmc1 Introduction

Facial trauma is continually increasing worldwide, being the most frequent type of pathology diagnosed and treated in oral and maxillofacial surgery services.1 Jaw fractures have a direct impact on masticatory function, and restoring occlusion is the gold standard for the treatment of jaw fractures.2 However, delayed treatment, improper treatment methods, and postinjury or postoperative infections can lead to malocclusion of jaw fractures, which mainly manifest with symptoms such as dentognathic deformities, malocclusion, limited mouth opening, and sleep apnea syndrome.3 Additionally, jaw fractures are often accompanied by dental trauma, resulting in tooth displacement, tooth defects, and dentition defects/loss.4 The prevalence of dental trauma among patients hospitalized for maxillofacial trauma is as high as 63%.5 Timely treatment of jaw fractures can maintain the occlusal repair space6, but for patients with malocclusion caused by old jaw fractures and dental trauma, the occlusal relationship cannot be restored in a timely manner. Over time, complications such as crown elongation, insufficient vertical repair space, and even temporomandibular joint disorder may occur, increasing the difficulty of occlusal reconstruction.7

Dental implants are the third set of teeth in humans and have been extensively used in the repair and treatment of dentition defects.8 Patients with traumatic tooth loss also have a high clinical demand for dental implant prostheses.9 Patients with malocclusion of old jaw fractures accompanied by dentition defects face greater clinical challenges in occlusal reconstruction with a dental implant prosthesis due to insufficient jawbone mass, insufficient alveolar bone mass, poor soft tissue conditions, and abnormal occlusal space.10 This study applied the 3-phase restoration concept, involving phase I: reconstruction of the correct 3-dimensional (3D) jaw maxillo-mandibular relationship, phase II: reconstruction of soft and hard tissue conditions (alveolar bone), and phase III: implant prosthesis and occlusal reconstruction. A retrospective study of clinical cases and analysis of clinical treatment effects were also performed.

2 Methods

2.1 Baseline characteristics

Fifteen patients with old jaw fractures and dentition defects who underwent occlusal reconstruction in the Department of Oral and Maxillofacial at the Third Affiliated Hospital of Air Force Military Medical University from January 2018 to December 2022 were enrolled (Table 1). The inclusion criteria were as follows: (1) old jaw fractures and dentition defects induced by trauma or previous training injury; (2) occlusal disturbance; (3) age of 18 – 50 years; (4) more than 1 year of continuous follow-up after occlusal reconstruction treatment; (5) good general condition without surgical contraindications; and (6) acceptance of the treatment plan and signed informed consent. The exclusion criteria were as follows: (1) severe coagulation disorders; (2) severe immune system disorders; (3) uncontrolled diabetes; (4) poor compliance; (5) local radiotherapy in the neck or maxillofacial region or systemic chemotherapy within 6 months; (6) heavy smokers and drinkers; and (7) poor general condition or with intolerance to surgery due to severe systemic diseases.Table 1 Occlusal reconstruction in patients with old jaw fractures and dentition defects.

Table 1No.	Sex	Age (year)	Old jaw fracture and dentition defect location	Three-phase restoration	Complications	
Phase I	Phase II	Phase III	
1	Male	40	Jaw: maxilla
Dentition: maxilla and mandible	Mode of orthognathic surgery: LeFort I osteotomy of maxilla.
Maxillary reconstruction microsurgery: fibular flap	Soft tissue augmentation: FGG	Implant-supported removable denture	Soft tissue graft infection	
2	Male	53	Jaw: mandible
Dentition: maxilla and mandible	Mode of orthognathic surgery: BSSRO of the mandible
Joint treatment: arthroplasty	Bone augmentation: GBR
Soft tissue augmentation: FGG and vestibuloplasty	Implant-supported fixed denture		
3	Female	31	Jaw: maxilla
Dentition: maxilla	Mode of orthognathic surgery: LeFort I osteotomy of maxilla
Joint treatment: disc reduction anchorage	Bone augmentation: GBR
Soft tissue augmentation: CTG	Implant-supported fixed denture		
4	Female	42	Jaw: maxilla
Dentition: maxilla	Open reduction and internal fixation for old jaw fractures	Bone augmentation: onlay bone grafting, bone splitting and bone grafting	Implant-supported fixed denture		
5	Male	26	Jaw: mandible
Dentition: maxilla and mandible	Mode of orthognathic surgery: BSSRO, subapical osteotomy, and free bone grafting of the mandible	Soft tissue augmentation: FGG	Implant-supported removable denture with telescopic crowns and fixed denture		
6	Female	18	Jaw: mandible
Dentition: maxilla	Microsurgery
Open reduction and internal fixation for old jaw fractures	Bone augmentation: onlay bone grafting	Implant-supported fixed denture		
7	Male	24	Jaw: maxilla and mandible
Dentition: maxilla and mandible	Open reduction and internal fixation for old jaw fractures	Bone augmentation: GBR, onlay bone grafting
Soft tissue augmentation: FGG	Implant-supported fixed denture	Titanium mesh exposure	
8	Male	20	Jaw: mandible
Dentition: maxilla and mandible	Open reduction and internal fixation for old jaw fractures	Bone augmentation: onlay bone grafting
Soft tissue augmentation: FGG	Implant-supported fixed denture		
9	Female	39	Jaw: maxilla
Dentition: maxilla	Debridement of the infected foci for jaw fractures
Microsurgery	Bone augmentation: GBR
Soft tissue augmentation: FGG	Implant-supported fixed denture		
10	Female	34	Jaw: maxilla
Dentition: maxilla	LeFort I osteotomy of maxilla	Bone augmentation: onlay bone grafting, GBR
Soft tissue augmentation: FGG	Implant-supported fixed denture		
11	Male	20	Jaw: mandible
Dentition: maxilla and mandible	LeFort I osteotomy of maxilla
BSSRO of the mandible
Temporomandibular joint surgery	Bone augmentation: GBR
Soft tissue augmentation: CTG + FGG	Implant-supported fixed denture		
12	Female	45	Jaw: maxilla
Dentition: maxilla	LeFort I osteotomy of maxilla		Implant-supported fixed denture		
13	Male	20	Jaw: mandible
Dentition: mandible	Debridement of the infected foci in the mandible
Mandibular reconstruction microsurgery: iliac bone flap		Implant-supported removable denture	Peri-implantitis, implant abscission	
14	Male	38	Jaw: mandible
Dentition: maxilla and mandible	Partial resection of the right mandible
Mandibular reconstruction microsurgery: fibular flap	Soft tissue augmentation: FGG	Implant-supported removable denture	Peri-implantitis, implant abscission	
15	Male	32	Jaw: mandible
Dentition: maxilla and mandible	Debridement of the infected foci in the mandible
Mandibular reconstruction microsurgery: iliac bone flap	Soft tissue augmentation: FGG	Implant-supported removable denture		
FGG: free gingival graft; BSSRO: bilateral sagittal split osteotomy; GBR: guided bone regeneration; CTG: connective tissue graft.

2.2 Therapeutic methods

Techniques such as open reduction and internal fixation for old jaw fractures, orthognathic surgery, microsurgery, and distraction osteogenesis were adopted to reconstruct the correct 3D spatial positions of the maxilla and mandible in phase I. Alveolar bone augmentation was achieved through methods including guided bone regeneration, osteotomy, and onlay bone grafting. Free gingival graft (FGG) and connective tissue graft (CTG) surgical techniques were employed for soft tissue augmentation in the implant area in phase II. And in phase III, based on a comprehensive analysis of the patient's subjective needs and actual anatomical conditions, implant-supported overdentures or implant-supported fixed dentures were selected to complete the reconstruction of occlusal function.

2.3 Observation indicators and evaluation criteria

We formulated an evaluation scale for successful occlusal reconstruction in patients with old jaw fractures and dentition defects (Table 2).11 The evaluation criteria for the success of phase I reconstruction of the 3D jaw positional relationship involved the evaluation of the reduction position, facial symmetry, incidence of complications, and mouth opening. The evaluation criteria for the success of phase II reconstruction of alveolar bone soft and hard tissue consisted of assessments of exposure, infection, and complications. The evaluation criteria for the success of phase III implant prosthesis and occlusal reconstruction included the occurrence of infection, bone resorption, X-ray transmission area around the implant, and the masticatory efficiency of the implant.Table 2 Evaluation scale for successful occlusal reconstruction in patients with old jaw fractures and dentition defects.

Table 2Score	Two points	One point	Zero point	
Reconstruction of the 3D jaw positional relationship in phase I	
 Reduction position	Functional reduction	Anatomical reduction	Failure to achieve	
 Complications	No infection	Infection	Delayed union of fracture	
 Facial symmetry	Facial symmetry	Slight facial asymmetry	Asymmetry or deformity	
 Mouth openin	No restriction	Mild	Moderate or more	
Reconstruction of alveolar bone soft and hard tissues in phase II	
 Exposure	No exposure	Little exposure	Exposure over 1/2	
 Infection	No infection No loosening	Mild infection	Uncontrollable infection	
 Mobility		Slight loosening	Loosening	
Implant prosthesis and occlusal reconstruction in phase III	
 Infection	No infection	Mild infection	Uncontrollable infection	
 Bone loss at the 1st year	< 1.5 mm	1.5 mm	> 1.5 mm	
 X-ray transmission area around the implant	No	No	Yes	
 Masticatory efficiency	> 70%	70%	< 70%	
Patient satisfaction	
 Phonetics	Satisfaction	General	Dissatisfaction	
 Chewing	Satisfaction	General	Dissatisfaction	
 Comfort	Satisfaction	General	Dissatisfaction	
 Aesthetics	Satisfaction	General	Dissatisfaction	
3D: 3-dimensional.

The evaluation of patient subjective satisfaction was conducted in the form of a questionnaire to investigate their satisfaction with the restoration efficacy. The questionnaire was mainly composed of patient satisfaction with masticatory efficiency, phonetics, aesthetics, comfort, and overall satisfaction. Each item was scored as satisfaction, general, and dissatisfaction.12 All questionnaires were administered by the same trained professional.

2.4 Statistical processing

All data were analyzed by SPSS 20.0 and plotted using GraphPad 8.0.2 software. Quantitative data conforming to a normal distribution are described by the mean ± standard deviation. The 2 groups were compared using independent sample t-tests, and p < 0.05 was considered statistically significant.

3 Results

There were 15 patients with old jaw fractures and dentition defects, with an average age of 32 years (ranging from 18 to 53 years), including 7 cases of malocclusion of single maxillary fracture, 6 of malocclusion of single mandible fracture, and 2 of malocclusion of both maxillary and mandible fractures. There were 5 cases of single maxillary dentition defects, 2 of single mandibular dentition defects, and 8 of both maxillary and mandibular dentition defects. In the reconstruction of the correct 3D jaw position, there were 5 cases of LeFort I osteotomy of the maxilla, 3 of bilateral sagittal split osteotomy of the mandible, 4 of open reduction and internal fixation of old jaw fractures, 3 of temporomandibular joint surgery, and 4 of distraction osteogenesis. All patients underwent jawbone augmentation, 4 of whom underwent free composite vascularized bone flap (26.66%), and the rest underwent local alveolar bone augmentation. FGG and CTG were the main methods for soft tissue augmentation, accounting for 73.33%. The change before and after occlusal reconstruction treatment was significant (p < 0.001) (Table 3).Table 3 Comparison of evaluation scale of pre- and post-occlusal reconstruction.

Table 3Item	Preoperative	Postoperative	T value	p value	
Phase I: 3D reconstruction	3.47 ± 0.96	7.40 ± 0.71	12.34	< 0.001	
Phase II: alveolar reconstruction	3.13 ± 1.02	5.47 ± 0.96	6.23	< 0.001	
Phase III: implant prosthesis and occlusal reconstruction	3.20 ± 0.49	7.27 ± 1.69	6.24	< 0.001	
Patient satisfaction	3.20 ± 1.76	7.53 ± 1.20	7.61	< 0.001	
3D: 3-dimensional.

3.1 Implant success rate

For 15 patients with old jaw fractures and dentition defects, a total of 81 implants were implanted, of which 5 were dislodged. The success rate of implants was 93.83%.

3.2 Peri-implant soft tissues

Among the 15 patients with old jaw fractures and dentition defects, 2 developed peri-implantitis, 1 adopted free composite vascularized iliac bone flaps for mandibular reconstruction, and 1 adopted a free composite vascularized fibular flap for maxillary reconstruction.

3.3 Implant prosthesis

Among the 15 patients with old jaw fractures and dentition defects, 11 were treated with implant-supported fixed dentures and 4 were treated with implant-supported removable dentures. The results suggested that both implant-supported overdentures and fixed dentures could effectively restore the phonetics and masticatory function of patients.

3.4 Patient subjective satisfaction

The satisfaction questionnaire results showed that patients expressed great satisfaction in terms of masticatory efficiency, phonetics, aesthetics, comfort, and overall satisfaction before and after implant treatment. Among them, patients with implant-supported overdentures had higher satisfaction with aesthetics than those with implant-supported fixed dentures.

3.5 Representative case

One male patient aged 32 years, had a car accident in October 2018 and underwent “open reduction and internal fixation for multiple maxillofacial fractures” at a local hospital (Fig. 1). The patient complained of occlusal discomfort after surgery and came to our hospital for treatment in May 2019. Specialized examinations revealed asymmetric facial appearance, disordered occlusion, maxillary and mandibular jaw dentition defects, and palatal fistula (Fig. 2, Fig. 3). CT examination revealed a maxillary malocclusion accompanied by partial loss of the left maxilla. In Phase I, LeFort I osteotomy of the maxilla was performed to restore the occlusal relationship of the remaining teeth, while free vascularized fibular flaps were used to reconstruct the left maxilla and repair the palatal fistula (Fig. 4). In Phase II, vestibuloplasty and FGG were performed (Fig. 5). Phase III, implantation was performed with implant-supported removable dentures in the maxilla and implant-supported fixed dentures in the mandible, achieving occlusal reconstruction (Fig. 6, Fig. 7). After more than 2 years of follow-up, the patient was satisfied, and the implants were all in good condition (Fig. 8).Fig. 1 CT images of the patient after a car accident.

Fig. 1

Fig. 2 Preoperative facial images of the patient with old jaw fractures and dentition defects.

Fig. 2

Fig. 3 Intraoral images of the patient with old jaw fractures and dentition defects

Fig. 3

Fig. 4 Virtual orthognathic and fibular flap reconstruction for old jaw fractures and dentition defects.

Fig. 4

Fig. 5 Simultaneous maxillary vestibuloplasty and free gingival graft.

Fig. 5

Fig. 6 Intraoral images after implantation.

Fig. 6

Fig. 7 Intraoral images after occlusal reconstruction.

Fig. 7

Fig. 8 Facial images after occlusal reconstruction.

Fig. 8

4 Discussion

Dental implants, known as the third set of teeth in humans, have been widely applied in the repair and treatment of odontogenic dentition defects and trauma-induced dentition defects, achieving stable clinical therapeutic efficacy.13 However, the clinical application of dental implants in the reconstruction of occlusal function in patients with old jaw fractures and dentition defects is different from conventional implant prostheses for dentition defects. First, old jaw fractures caused by trauma are often accompanied by abnormalities in the 3D spatial positions of the maxilla and mandible.14 It is necessary to improve the relative 3D spatial positions of the maxilla and mandible through open reduction and internal fixation for old jaw fractures, orthognathic surgery, or distraction osteogenesis, laying the foundation for subsequent occlusal reconstruction. In phase I, reconstruction of the 3D spatial position of the jaw requires the clinical assistance of digital-assisted surgical technology.15 Multidisciplinary consultations such as prosthodontics and dental implantology are conducted before treatment to develop the final implant-supported occlusal reconstruction plan, formulating a phase I surgical regimen through backward inference. With the assistance of modern digital tools such as digital 3D-printed surgical guides and navigation, surgical treatment is performed. Digital-assisted surgical technology was utilized for 15 patients with old jaw fractures and dentition defects in this study, achieving ideal relative 3D spatial positions of the maxilla and mandible. The application rate of open reduction and internal fixation for old jaw fractures was 26.66% and that of orthognathic surgery was 46.66%, which are the most commonly used surgical procedures for old fractures. The application rate of microsurgery was 26.66%, which is mainly suitable for the treatment of old fractures accompanied by jaw necrosis and jaw defects and can be performed simultaneously with other surgical methods, such as orthognathic surgery for jaw 3D spatial correction and soft and hard tissue augmentation.

Dental defects caused by trauma are often accompanied by insufficient alveolar soft and hard tissues, and implant prostheses require soft and hard tissue augmentation.16 Therefore, treatment in phase II for patients with old jaw fractures and dentition defects augments alveolar bone and improves gingival conditions, laying the foundation for later implant prostheses. All 15 patients with old jaw fractures and dentition defects in this study underwent bone augmentation. Except in the microsurgical reconstruction cases mentioned above, local alveolar bone augmentation was performed. One patient needed significant bone augmentation despite postoperative titanium mesh exposure after surgery, and the implant prosthesis was eventually installed. Healthy keratinized mucosal tissue around the implant is beneficial to achieve long-term stable implant prosthesis effects.17 The soft tissue augmentation in the enrolled patients differed from the implant area of conventional natural tooth loss by having a larger area of keratinized mucosal defect. In addition, shallow vestibular sulcus, poor soft tissue quality, etc. often occur in the edentulous area due to trauma and multiple surgeries. Soft tissue augmentation is necessary before implant prosthesis.18 The main methods of soft tissue augmentation for the enrolled patients were FGG and CTG, which accounted for 73.33% of all cases. Except for 1 failed case of mucosal implant infection, all other patients achieved ideal soft tissue augmentation. For large-area FGG implants, suturing and local compression to fit the free tissue flap to the periosteum is a key surgical technique that can significantly improve the survival rate of the implant.19 In this study, a patient who received composite vascularized iliac bone flaps to reconstruct the mandible was found to have insufficient height of the reconstructed jaw in the posterior dental region and a shallow lingual vestibular sulcus. Neither FGG nor CTG implants were able to achieve the desired results, resulting in peri-implant bone resorption and implant abscission. Therefore, a treatment plan in phase II based on the actual anatomical conditions of the patient was needed to restore the soft and hard tissue repair structure in the edentulous region, laying the foundation for subsequent implant prostheses.

Patients with jaw fractures and dentition defects underwent phases I and II treatments to restore the relative 3D spatial position of the jaw and the soft and hard tissue conditions of the edentulous region. However, due to the long treatment cycle being necessary for old trauma, the edentulous region may have insufficient repair space induced by factors such as teeth elongation and inclination, which requires a dental outpatient department consultation and collaboration, such as orthodontic, dental, and prosthesis, as necessary, followed by implant prosthesis and occlusal reconstruction in phase III. Occlusal reconstruction in phase III requires a comprehensive multivariate analysis based on external factors, such as the patient's economic compensation and payment methods, and factors such as the patient's oral anatomical condition, oral hygiene, and chewing habits to select implant-supported denture restoration methods.20 The traditional treatment for patients with old jaw fractures and dental defects is to treat the jaw fracture through maxillofacial surgery and refer the patient to an outpatient clinic for restoration of the dental defect after healing. Inpatient and outpatient treatment are usually independent. Compared with traditional treatment, this study proposes a phased sequential comprehensive treatment plan. Multidisciplinary consultation is necessary for patients with old jaw fractures and dentition defects undergoing occlusal reconstruction, including a comprehensive and systematic examination and analysis, to formulate a thorough treatment plan. Sequential therapy has achieved good therapeutic efficacy, but there are still shortcomings, such as long treatment times and high operation frequencies. Shortening the overall treatment time should be the focus of subsequent research.

In conclusion, phased sequential comprehensive treatment for occlusal reconstruction of old jaw fractures and dentition defects, consisting of 3D jaw spatial correction, alveolar bone augmentation and soft tissue augmentation, and implant-supported occlusal reconstruction, can achieve satisfactory clinical treatment effects.

Funding

Project of State Key Laboratory of Military Stomatology (2021ZA07 ), Shaanxi Provincial Key Research and Development Program (2023-YBSF-291 ), The Science and Technology Project of Xi'an City (22YXYJ0116 ).

Ethical statement

This retrospective study was carried out using the opt-out method for the case series of our hospital. The study was approved by the Ethics Committee of the Third Affiliated Hospital of Air Force Military Medical University (approval no. KQ-YJ-2023-140) and was conducted in accordance with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Informed consent was waived by our Institutional Review Board because of the retrospective nature of our study.

Declaration of competing interest

No potential conflict of interest was reported by the authors.

Author contributions

Ming-Chao Ding: conceptualization, methodology, formal analysis, writing-original draft, writing-review and editing, and project administration.

Bo-Ya Jing: conceptualization, investigation, data curation, writing-original draft, writing-review and editing, and supervision.

Jin Shi: writing-original draft.

Liu Yang: formal analysis.

Xiang-Dong Liu: writing-original draft.

Jing-Fu Wang: resources, validation.

Shuang Qu: writing-original draft.

Jia-Wu Liang: writing-review and editing.

Zi-Hao Tang: data curation.

Lei Tian: conceptualization, supervision, project administration, funding acquisition.

Jin-Long Zhao: conceptualization, supervision, project administration.

Peer review under responsibility of Chinese Medical Association.
==== Refs
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