Long-term stability of jaw reconstruction with microvascular bone flaps: A prospective longitudinal study.

OBJECTIVES: Microvascular bone flap jaw reconstruction has achieved satisfactory clinical outcomes. However, little is known about the long-term stability of the reconstructed jaw. This prospective longitudinal study aimed to investigate the long-term stability of jaw reconstruction and factors that were associated with it. METHODS: Patients with successful computer-assisted osseous free-flap jaw reconstruction in the Department of Oral and Maxillofacial Surgery, Queen Mary Hospital, Hong Kong were recruited for this prospective longitudinal study. The three-dimensional jaw models at the pre-operative plan, post-operative 1-month, and 2 years were aligned and compared. RESULTS: A total of 69 patients were recruited, among which 48 patients were available for the long-term analysis. Compared to 1-month after surgery, further deviation from the pre-operative plan was observed at post-operative 2 years. Lack of accuracy in surgery, segmental mandible resection especially with the involvement of mandible angles, and post-operative radiation therapy were identified as the significant factors affecting the positional stability of the reconstructed jaw (p < 0.05). Stable reconstruction was observed in the subgroup analysis of patients without post-operative radiation therapy. CONCLUSION: Up to the best of our knowledge, this is the first prospective longitudinal study reporting the long-term stability of jaw reconstruction and its affecting factors. Our data demonstrated that the reconstructed jaw position lacked stability over the postoperative period. How to improve long-term stability of reconstructed jaw thus optimize the functional outcomes warrants further studies.

A quantitative comparison of bone resection margin distances in virtual surgical planning versus histopathology: a prospective study.

BACKGROUND: Positive bone margins have been shown to be associated with worse locoregional control and survival performance in oral oncology patients. With the application of computer-assisted surgery and patient-specific surgical guides, the authors can accurately execute the preoperative osteotomy plan. However, how well the authors can predict the margin distance in the final histopathology with a preoperative computed tomography (CT) scan, the factors associated with it, and how much leeway CT should spare when designing the osteotomy planes during virtual surgical planning (VSP) remain to be investigated. MATERIALS AND METHODS: Patients from January 2021 to December 2022 with benign or malignant jaw tumors and with signs of bone marrow involvement in the preoperative CT scan in our center were prospectively recruited to the study. VSP and measurement of the closest margin distance in the CT scan were performed by the single team of surgeons. The resection specimen was processed, and the margin distances were measured by a dedicated senior pathologist with the knowledge of orientation of the osteotomy planes. RESULTS: A total of 35 patients were recruited, with 21 malignant and 14 benign cases. Sixty-eight bone margins were quantitatively analyzed. No significant difference in margin distances measured from the CT scan and final histopathology was detected ( P =0.19), and there was a strong correlation between the two (r s =0.74, P <0.01). A considerable amount of variance was detected in the level of discrepancy between margin distances measured in the CT scan and final histopathology (overall SD=6.26 mm, malignancy SD=7.44 mm, benign SD=4.40 mm). No significant correlation existed between the two margin distances when only maxilla tumor margins were assessed ( P =0.16). CONCLUSION: The bone margin distance in VSP is reliably correlated to the final pathological margin distance. A leeway distance of 15mm and 9mm should be considered when designing the osteotomy planes for malignancy and benign cases, respectively. Extra attention should be paid to maxilla cases when predetermining the osteotomy planes during VSP.

Platinum-based chemotherapy induces demyelination of Schwann cells in oral squamous cell carcinoma treatment.

BACKGROUND: Cisplatin, carboplatin, and oxaliplatin are the only three platinum-based antineoplastic drugs that have been accepted worldwide for treating various cancers. Up to 83.6% of patients treated with platinum-based antineoplastic drugs will develop chemotherapy-induced peripheral neuropathy (CIPN), manifesting as sensory paresthesias, dysesthesias, and hypoesthesias that can cause significant adverse impact to daily activities. AIM: To investigate how these three platinum-based drugs affect mitochondrial function and myelination state of Schwann cells and the signalling pathway involved. METHOD: 2 µM Cisplatin, 20 µM carboplatin, and 1 µM oxaliplatin were used to inhibit the growth of CAL-27 by 20% respectively. These drugs were then used to induce chemotherapy-induced peripheral neuropathy in Rat Schwann Cells (RSC96). The changes in cell metabolism and myelin formation in RSC96 were investigated. RESULT: Cisplatin and carboplatin, but not oxaliplatin increased intracellular and mitochondrial reactive oxygen species in RSC96. Only Cisplatin and carboplatin decreased mitochondrial membrane potential (ΔΨm) and ATP production in RSC96. Both Cisplatin and carboplatin led to demyelination of RSC96, characterized by increased expression of p75NTR and decreased expression of myelin protein zero (MPZ). CONCLUSION: Cisplatin and carboplatin, but not oxaliplatin, caused mitochondrial dysfunction and induced demyelination in RSC96 while showing similar toxicity to head and neck cancer cells. Oxaliplatin may be a potential chemotherapy drug to prevent CIPN in patients with head and neck cancer.

The contralateral-based submental artery island flap: feasibility and oncological safety in oral cancer-related defect reconstruction.

OBJECTIVES: Oncologic risk is a serious concern of submental artery island flaps. Here, we introduce the contralateral-based submental artery island flap (C-SAIF) and demonstrate its feasibility and long-term oncological safety in reconstructing oral cancer-related defects. METHODS: An anatomical study was performed concentrating on the pedicle length in seven cadavers. Then, a retrospective study was carried out on C-SAIF patients operated on by a single team. The standard surgical technique of C-SAIF was conducted. Outcomes including operative time, length of hospital stay, volume of intraoperative blood loss, and scores of the Multidisciplinary Salivary Gland Society (MSGS) questionnaire were compared with a similar cohort reconstructed with anterolateral thigh free flap (ALTF). In addition, oncological outcomes were evaluated by the 5-year cumulative survival rate between C-SAIF and ALTF patients. RESULTS: The pedicle length of C-SAIF was sufficient for the flap to be extended to the contralateral oral cavity. Fifty-two patients were included in the retrospective study, and nineteen of them underwent reconstruction with C-SAIF. The operative time of C-SAIF was shorter (p = 0.003), and the intraoperative blood loss was less (p = 0.004) than that of ALTF. There was no difference in MSGS scores. The results of survival analysis revealed comparable survival curves for the two groups in terms of overall survival, disease-specific survival, and disease-free survival. CONCLUSION: C-SAIF is a feasible and reliable flap for reconstructing oral cancer-related defects. Moreover, it is an effective island flap to preserve the perforator and pedicle without compromising oncological safety.

Cutting-edge patient-specific surgical plates for computer-assisted mandibular reconstruction: The art of matching structures and holes in precise surgery.

Objectives: Cutting-edge patient-specific surgical plates (PSSPs) are supposed to improve the efficiency, precision, and functional outcomes of mandibular reconstruction. This study characterized the premium role of PSSPs in precise surgery and explored their working principles in computer-assisted mandibular reconstruction (CAMR). Methods: The PSSPs-enhanced surgical precision was investigated through the model surgery and representative cases. Spatial deviations of reconstruction were characterized by comparing the reconstructed mandible with the virtually designed mandible. Working principles of PSSPs were distinguished by a review of evolving surgical techniques in CAMR. Results: In the model surgery, spatial deviations between the virtually planned mandible and the reconstructed mandible were 1.03 ± 0.43 mm in absolute distance deviation, 1.70 ± 1.26 mm in intercondylar length, and 1.86 ± 0.91 mm in intergonial length in the study group of PSSPs, significantly smaller than in the control group of conventional prebent surgical plates. Meanwhile, in the study group, distance deviations were 0.51 ± 0.19 mm in bone-plate distance and 0.56 ± 0.28 mm in drilled screw holes, indicating the art of matching structures and holes. The PSSPs-enhanced CAMR was further demonstrated in three representative cases of mandibular reconstruction. Finally, four primary techniques of CAMR were summarized based on a review of 8,672 articles. The premium role of PSSPs was distinguished by the benefits of matching structures and holes. Conclusions: The PSSPs-enhanced surgical precision was verified through the model surgery and demonstrated in human surgery. Compared to other surgical techniques of CAMR, PSSPs contributed to the precise surgery by the art of matching structures and holes.

The effect of drug holiday on preventing medication-related osteonecrosis of the jaw in osteoporotic rat model.

Background: Medication-related osteonecrosis of the jaw (MRONJ) is a severe complication associated with antiresorptive medications managing osteoporosis, such as bisphosphonates (BPs). To date, there is very limited evidence from prospective, controlled studies to support or refute the controversial prevention regimen that if a discontinuation of BPs before dentoalveolar surgery, so called "drug holiday", is effective in reducing the risk of MRONJ development in patients with osteoporosis. We proposed an experimental animal study, aiming to investigate the prevention of MRONJ following tooth extractions in osteoporotic condition, with the implementation of a BP drug holiday. Methods: Twenty rats were subjected to bilateral ovariectomy. After establishing the osteoporotic condition, all rats were exposed to weekly injections of zoledronate acid (ZA) for 8 weeks. After ZA treatment, 10 rats were subjected to dental extraction and defined as control group, and the rest 10 rats assigned to the DH group had a drug holiday of 8 weeks prior to dental extraction. Eight weeks after the dentoalveolar surgery, bone turnover biomarker in serum, occurrence of MRONJ-like lesion and histomorphometric assessment of osteonecrosis in mandible, and bone microarchitecture indices in femur, were examined. Results: Eight weeks after dental extraction, the DH group showed a recovered osteoclastic activity, indicated by significantly increased number of osteoclasts in the mandibles and serum level of C-terminal telopeptides of type I collagen, as compared to the control group. No significant differences were observed in the gross-view and histological occurrences of MRONJ-like lesions between the two groups.There was no significant difference in bone microarchitecture in the femur between the control and DH groups before ZA therapy and 8 weeks after dental extraction. Conclusion: Our data provided the first experimental evidence in the osteoporotic animal model that the implementation of a BP holiday in prior to dental extractions could partially recover osteoclastic activity, but could not alleviate the development of MRONJ-like lesion or exacerbate the osteoporotic condition in the femur. Longer-term drug holiday, or combination of drug holiday and other prophylaxes to prevent MRONJ in patients with osteoporosis could be worth exploring in future studies, to pave the way for clinical managements. The translational potential of this article: This in vivo prospective study reported that a recovery of osteoclastic activity by a BP drug holiday for 8 weeks in osteoporosis rats did not alleviate the development of MRONJ-like lesion followed by dental extractions. It contributes to the understanding of regimens to prevent MRONJ.

A neural-related gene risk score for head and neck squamous cell carcinoma.

OBJECTIVES: This study aimed to establish a neural-related gene risk score (NRGRS) for the prediction of head and neck squamous cell carcinoma prognosis and explore its predictive value on the benefit of immune checkpoint inhibitor therapy. METHODS: Based on the transcriptome data of HNSCC patients (n = 546) from The Cancer Genome Atlas database, 37 neural-related hub genes were identified by weighted gene co-expression network analysis. Four genes (ITGA5, PYGM, GNG7 and ATP2A3) were identified to construct NRGRS using Lasso-Cox regression method based on the derivation cohort and validated in the Gene Expression Omnibus cohort (n = 109). The survival analysis was performed to validate the prognostic value of NRGRS and immune characteristics in NRGRS-defined subgroups were analyzed. RESULTS: NRGRS-high patients had a worse overall survival than NRGRS-low patients. Tumors with high NRGRS were more likely to have high infiltration of naive CD4+ T cells, M0, M2 macrophages and resting mast cells, which illustrated suppressive immunity and less benefit from immunotherapy therapy. CONCLUSION: NRGRS strongly correlates with survival and is a promising biomarker to predict immunotherapy benefits for head and neck cancer patients. This study provides evidence for the potential correlation between neural-related transcriptome alteration and immune activity.

Biodegradable magnesium implant enhances angiogenesis and alleviates medication-related osteonecrosis of the jaw in rats.

Background: Medication-related osteonecrosis of the jaw (MRONJ) is a serious complication associated with antiresorptive and antiangiogenic medications, of which impaired angiogenesis is a key pathological alteration. Since Magnesium (Mg)-based implants possess proangiogenic effects, we hypothesized that the biodegradable Mg implant could alleviate the development of MRONJ via enhancing angiogenesis. Methods: MRONJ model was established and divided into the Veh â€‹+ â€‹Ti group (Vehicle-treated rat, with Titanium (Ti) implant), BP â€‹+ â€‹Ti group (Bisphosphonate (BP)-treated rat, with Ti implant), BP â€‹+ â€‹Mg group (BP-treated rat, with Mg implant), BP â€‹+ â€‹Mg â€‹+ â€‹SU5416 group (BP-treated rat, with Mg implant and vascular endothelial growth factor (VEGF) receptor-2 inhibitor), BP â€‹+ â€‹Mg â€‹+ â€‹BIBN group (BP-treated rat, with Mg implant and calcitonin gene-related peptide (CGRP) receptor antagonist), and BP â€‹+ â€‹Mg â€‹+ â€‹SU5416+BIBN group (BP-treated rat, with Mg implant and VEGF receptor-2 inhibitor and CGRP receptor antagonist). The occurrence of MRONJ, alveolar bone necrosis, new bone formation and vessel formation were assessed by histomorphometry, immunohistochemistry, and micro-CT analysis. Results: Eight weeks after surgery, the BP â€‹+ â€‹Mg group had significantly reduced occurrence of MRONJ-like lesion and histological osteonecrosis, increased bone microstructural parameters, and increased expressions of VEGFA and CGRP, than the BP â€‹+ â€‹Ti group. By simultaneously blocking VEGF receptor-2 and CGRP receptor, the vessel volume and new bone formation in the BP â€‹+ â€‹Mg group were significantly decreased, meanwhile the occurrence of MRONJ-like lesion and histological bone necrosis were significantly increased. Conclusion: Biodegradable Mg implant could alleviate the development of MRONJ-like lesion, possibly via upregulating VEGF- and CGRP-mediated angiogenesis. Mg-based implants have the translational potential to be developed as a novel internal fixation device for patients with the risk of MRONJ. The Translational potential of this article: This work reports a biodegradable Mg implant which ameliorates the development of MRONJ-like lesions possibly due to its angiogenic property. Mg-based implants have the potential to be developed as a novel internal fixation device for patients at the risk of MRONJ.

A Comprehensive Approach for Measuring Spatial Deviations of Computer-Assisted Mandibular Reconstruction.

BACKGROUND: Computer-assisted surgery has become the mainstream in mandibular reconstruction, but the lack of a standard measuring approach for spatial deviations of mandible hinders postoperative verification and the comparison of different subjects. This study aims to set up a comprehensive approach for measuring spatial deviations of computer-assisted mandibular reconstruction. METHODS: A systematic review was conducted to extract all measurements for computer-assisted mandibular reconstruction. Thereafter, eligible measurements were included in the authors' comprehensive approach, which categorized the measurements according to different anatomical structures and landmarks. RESULTS: A total of 80 studies were included in the authors' systematic review, and 31 measurements were extracted. The authors established a comprehensive panel of anatomical landmarks to facilitate measurement, including parts, points, lines, planes, and angles. These measurements encompassed spatial deviations of the overall mandible, condyle, gonial angle, bone grafts, midline, surgical plate, osteotomy, and miscellaneous indicators. A calculation spreadsheet was developed to collect landmarks and compute deviations automatically with built-in formulas. Finally, a simplified panel of measurements was recommended for spatial deviations of mandibular reconstruction. CONCLUSIONS: A comprehensive approach for measuring spatial deviations of computer-assisted mandibular reconstruction was established. Future studies will confirm this approach as an effective and scientific system for postoperative verification of computer-assisted mandibular reconstruction.

Unexpected Change of Surgical Plans and Contingency Strategies in Computer-Assisted Free Flap Jaw Reconstruction: Lessons Learned From 98 Consecutive Cases.

BACKGROUND: Computer-assisted surgeries (CAS) are increasingly being adopted as the treatment of choice for jaw reconstructions with osseous free flaps. Although unexpected change of surgical plans remains a major concern of CAS, there are few studies focusing on this unfavorable clinical scenario. The aim of the present study was to investigate the rate of unexpected change of surgical plans and potential influential parameters, and to discuss the contingency strategies. METHODS: A retrospective study was performed to evaluate all the patients who underwent computer-assisted jaw resections and osseous free flap reconstructions. The postoperative radiographs were reviewed and compared with the preoperative surgical plans. Operating records were examined to analyze the reasons for unexpected change of surgical plans and the management. The potential influential parameters for the change of surgical plans were analyzed using Fisher-exact test. The difference was regarded as statistically significant for a p-value less than 5%. RESULTS: From Nov 2014 to Oct 2021, a total of 98 consecutive computer-assisted free flap jaw reconstruction cases with osseous free flaps were included in this study. Our experience showed that 5.1% of the patients (five cases) needed intra-operative change of the surgical plans. We summarized the unexpected change of surgical plans and the contingency strategies as four clinical scenarios, including extended resection and reconstruction, shortened resection and reconstruction, modified resection without changing reconstruction, and modified reconstruction without changed resection. None of the potential influential parameters was identified as significant in relation to unexpected change of surgical plans intraoperatively. CONCLUSION: Our experience shows that with the comprehensive methodology for computer-assisted free flap jaw reconstruction surgery planning, we can minimize the possibility of unexpected change of surgical plans during surgery. The lessons learned from our 98 consecutive cases can help beginners prevent unexpected change of surgical plans and rationalize contingency strategies in computer-assisted free flap jaw reconstruction.

Quinoline-cored Poly(Aryl Ether) Dendritic Organogels with Multiple Stimuli-Responsive and Adsorptive Properties.

Functional supramolecular gel materials have potential applications in sensors, optical switches, artificial antennae, drug delivery and so on. In this paper, quinoline-cored poly(aryl ether) dendritic organogelators were designed, synthesized and fully characterized. The gelation behaviour of the dendritic organogelator was tested in organic solvents, mixed solvents and ionic liquids. The dendron Q-G1 was found to be an efficient and versatile organogelator toward various apolar and polar organic solvents with the critical gelation concentrations (CGCs) approaching 1.2×10-2  mol/L, indicating one dendritic organogelator could immobilize 1.2×103 solvent molecules in the organogel network. Interestingly, these dendrons exhibited excellent gel formation in ionic liquids. Notably, these dendritic organogels were found to display multiple stimuli-responsive properties toward external stimuli including heat, ultrasound and shear stress, with a reversible sol-gel phase transition. In addition, the dendritic organogel could effectively adsorb heavy metals and organic dyes. The removal rate of Pb2+ was up to 20% and the adsorption rate for Rhodamine B was as high as 89%.

Nutritional status in patients of mandibular osteoradionecrosis: A single-institution experience.

BACKGROUND: Mandibular osteoradionecrosis (ORN) is a devastating complication secondary to the radiotherapy of head and neck cancer. The nutritional status of ORN patients is compromised, but remains rarely studied. We aimed to evaluate the overall nutritional status of patients with ORN and explore the risk factors behind poor nutrition. METHODS: This is a single-institution cross-sectional study. Patients diagnosed with ORN were consecutively recruited in a tertiary teaching hospital from July 2017 to August 2019. Multiple laboratory markers and physical indicators were examined to profile their nutritional status. The potential risk factors of poor nutrition were explored by logistic regression. RESULTS: A total of 107 patients with ORN were recruited. Among them, almost all patients (95.3%) had at least one laboratory marker lower than the normal physiological range. A total of 40 (37.5%) patients were categorized as undernutrition, who had lower serum albumin (mean difference: 1.8 ± 0.8 g/L; p = .02), prealbumin (mean difference: 26.8 ± 10.8 mg/L; p = .02), and BMI (3.8 ± 0.4 kg/m2 ; p < .0001) compared to patients of normal nutrition. Notably, the multivariate logistic regression indicated that patients with semi-liquid diet had 14.41 (95% CI: 3.03-68.54, p = .001) times; patients with liquid diet had 5.70 (95% CI: 1.55-20.98, p = .009) times more likely to be in undernutrition, as compared to patients with regular diets. CONCLUSIONS: This is the first study characterizing the poor nutritional status in ORN patients. Patients having semi-liquid or liquid diets tended to have poorer nutritional status. The nutritional status of ORN patients should be underlined for professional nutritional supports so as to enhance their quality of life. More studies are warranted.

Identifying unmet non-COVID-19 health needs during the COVID-19 outbreak based on social media data: a proof-of-concept study in Wuhan city.

BACKGROUND: The occupancy of healthcare resources by the COVID-19 outbreak had led to the unmet health needs of non-COVID-19 diseases. We aimed to explore whether the social media information could help surveil and understand the characteristics of unmet non-COVID-19 health needs during the COVID-19 outbreak in Wuhan city. METHODS: This was an observational study based on social media data. The study period was set during the 3 months of the COVID-19 outbreak. Non-COVID-19 urgent and emergent health needs in Wuhan city were derived from Sina Weibo-one of China's largest social media platforms. Lag Spearman correlation was used to investigate the epidemiological relationship between the COVID-19 outbreak and non-COVID-19 health needs. Patient's primary diseases and needed care were annotated and categorized according to the International Classification of Diseases 11th Revision. The delay time in seeking help was calculated and compared. RESULTS: After screening 114,795 Weibo posts, a total of 229 patients with non-COVID-19 health needs were included in our study. There were significant correlations between the daily number of COVID-19 cases at a 10-day lag, deaths at a 5-day lag, and non-COVID-19 Weibo. The actual number of non-COVID-19 patients with urgent and emergent health needs was estimated to be about 6,966. Patients with non-COVID-19 health needs were skewed to those aged 50 to 70 years. The non-COVID-19 diseases were diverse, with 46.3% as non-neoplastic diseases and 53.7% as neoplasms. The most needed cares were palliative cancer care (22.7%), chemotherapy (18.8%), and critical care (17.0%). The median delay in seeking help was 3 days [interquartile range (IQR), 1 to 15 days] for acute care, and 18.5 days (IQR, 6 to 30 days) for cancer care. CONCLUSIONS: Our preliminary findings in Wuhan city indicated that the social media data might provide a viable option to surveil and understand the unmet health needs during an outbreak. Those heterogeneous health needs derived from the social media data might inspire a more resilient healthcare system to address the unmet needs promptly.

The Learning Curve of Computer-Assisted Free Flap Jaw Reconstruction Surgery Using 3D-Printed Patient-Specific Plates: A Cumulative Sum Analysis.

BACKGROUND: Computer-assisted jaw reconstruction (CAJR) has benefits in reducing operation time and improving reconstruction accuracy, compared to conventional freehand jaw reconstruction. However, no information is available regarding learning curves in CAJR with the use of 3D-printed patient-specific surgical plates (PSSP). The purpose of this study was to assess surgical outcomes and learning curve for the first 58 consecutive CAJR using 3D-printed PSSP performed by a single surgical team in a single institution. METHODS: In a prospective study, consecutive patients who underwent free flap CAJR using 3D-printed PSSP were included. The determination of proficiency, based on the cumulative sum of surgical success (no major adjustment of 3D-printed PSSP, flap survival) passing the acceptable boundary line of cumulative sum analysis, was the primary outcome. To find out any potential factors influencing the learning curve, baseline characteristics of patients were compared before and after proficiency achievement. Secondary outcomes included inflexion points of the total operation time, blood loss, length of hospital stay, and bone graft deviation, measured by the cumulative sum analysis. RESULTS: From December 2016 to November 2020, 58 consecutive cases underwent surgery performed by a single surgical team. The overall surgical success rate was 94.8% (55/58). A three-stage learning curve of primary outcome was observed. The proficiency was achieved after 23 cases. The proportions of advanced tumor staging and concomitant surgery after obtaining proficiency were significantly higher than those before achieving proficiency (p = 0.046 and p < 0.001, respectively). Mean values of operation time, intraoperative blood loss, length of hospital stay, and bone graft deviation were 532.5 ± 119.2 min, 1,006.8 ± 547.2 ml, 16.1 ± 6.3 days, and 0.9 ± 1.2 mm, respectively. Two trends of learning curve were observed in the CUSUM analyses of total operation time, length of hospital stay, and bone graft deviation, in which the first and second inflexion points occurred between 8 and 17 cases and between 43 and 46 cases, respectively. CONCLUSION: Our results revealed a three-stage learning curve of CAJR with the use of PSSP, including initial learning, plateau, and overlearning. Based on CUSUM analysis, the surgical proficiency was achieved after 23 cases, and total operation time, length of hospital stay, and bone graft deviation stabilized after 8-17 cases.

The Impact of Coronavirus Disease 2019 on the Disease Pattern of Oral and Maxillofacial Surgery Inpatients: A Comparative Study.

Objective: Oral and maxillofacial surgery (OMFS) is a high-risk specialty involving airway and aerosol-generating procedures, which is potentially of more risk in the era of coronavirus disease 2019 (COVID-19). We aimed to identify the impact of COVID-19 on the disease pattern of OMFS inpatients and surgeries under general anesthesia in a comparative study. Materials and Methods: We reviewed the admission and operating theater records of OMFS patients from Jan 1 to Aug 31 in 2020 and 2019. The total number of cases, presenting disease patterns, and proportion of essential and non-essential medical services were compared between 2020 and 2019. Results: There were 664 admissions and 356 general anesthesia surgical procedures included in this study. Both admission and surgery numbers were significantly reduced in 2020, compared with 2019 (p = 0.012 and 0.007, respectively). The proportion of malignancy cases increased significantly, whereas that of cleft lip and palate and temporomandibular disorder (TMD) decreased. There was a significant increase in the proportion of essential services compared with non-essential services in 2020 compared with 2019. Conclusion: Our results first reported the epidemiological data of the impact of COVID-19 on OMFS disease pattern in a comparative study. The change of disease pattern and caseload will have a long-term impact on OMFS patient care, education, and training during the pandemic. Our paper provides evidence for health policy makers to consider the relocation of medical resources and optimization of medical education and services.

Artificial intelligence-enabled automatic segmentation of skull CT facilitates computer-assisted craniomaxillofacial surgery.

BACKGROUND: The image segmentation of skull CT is the cornerstone for the computer-assisted craniomaxillofacial surgery in multiple aspects. This study aims to introduce an AI-enabled automatic segmentation and propose its prospect in facilitating the computer-assisted surgery. METHODS: Three patients enrolled in a clinical trial of computer-assisted craniomaxillofacial surgery were randomly selected for this study. The preoperative helical CT scans of the head and neck region were subjected to the AI-enabled automatic segmentation in Mimics Viewer. The performance of AI segmentation was evaluated based on the requirements of computer-assisted surgery. RESULTS: All three patients were successfully segmented by the AI-enabled automatic segmentation. The performance of AI segmentation was excellent regarding key anatomical structures. The overall quality of bone surface was satisfying. The median DICE coefficient was 92.4% for the maxilla, and 94.9% for the mandible, which fulfilled the requirements of computer-assisted craniomaxillofacial surgery. CONCLUSIONS: The AI-enabled automatic segmentation could facilitate the preoperative virtual planning and postoperative outcome verification, which formed a feedback loop to enhance the current workflow of computer-assisted surgery. More studies are warranted to confirm the robustness of AI segmentation with more cases.

A Comparative Study on a Novel Fibula Malleolus Cap to Increase the Accuracy of Oncologic Jaw Reconstruction.

OBJECTIVES: Although computer-assisted surgery using fibula flap has been widely applied for oncologic jaw reconstruction in recent years, the inaccurate positioning of the fibula harvest guide brings sliding and rotational errors, which leads to compromised accuracy in simultaneous implant placement and dental rehabilitation. This study aimed to develop a novel three-dimensional (3D)-printed patient-specific fibula malleolus cap to increase oncologic reconstruction accuracy. METHODS: In this prospective comparative study with a recent historical control cohort, patients in need of oncologic jaw reconstruction with fibula free flaps were recruited. In the study group, the fibula was harvested with the guide of the malleolus cap, whereas in the control group, without the malleolus cap. Deviations of location and angulation of distal fibula osteotomies, jaw reconstruction segments, and simultaneous dental implants were compared. RESULTS: Twenty patients were recruited, with 10 in each arm. The application of the malleolus cap significantly reduced the deviations in locations and angles of distal fibula osteotomies, from 9.5 to 4.1 mm and 25.3° to 8.7°. For the simultaneous dental implants placed in the fibula flaps, there was a significant increase in the accuracy of implant platform locations (the average deviation from 3.2 to 1.3 mm), apex locations (from 3.8 to 1.5 mm), and angles (from 11.3° to 4.6°). No significant difference was detected in the accuracy of fibula reconstruction segments. CONCLUSIONS: We developed a novel fibula malleolus cap to overcome the sliding and rotational errors during fibula flap harvesting for oncologic jaw reconstruction, with increased accuracy in simultaneous dental implants. This is a step forward to achieve a satisfactory functional outcome of jaw reconstruction with dental rehabilitation.

Three-Dimensionally Printed Patient-Specific Surgical Plates Increase Accuracy of Oncologic Head and Neck Reconstruction Versus Conventional Surgical Plates: A Comparative Study.

BACKGROUND: Surgeons are pursuing accurate head and neck reconstruction to enhance aesthetic and functional outcomes after oncologic resection. This study aimed to investigate whether accuracy of head and neck reconstruction is improved with the use of three-dimensionally (3D)-printed patient-specific surgical plates compared with conventional plates. METHODS: In this comparative study, patients were prospectively recruited into the study group (3DJP16) with 3D-printed patient-specific surgical plates. The patients in control group with conventional surgical plates were from a historic cohort in the same unit. The primary end point of the study was the accuracy of head and neck reconstruction. The secondary end points were accuracy of osteotomy, intraoperative blood loss, total operative time, and length of hospital stay. RESULTS: The study recruited of 33 patients, including 17 in the study group and 16 in the control group. The patients' baseline characteristics were similar between the two groups. The absolute distance deviation of the maxilla or mandible was 1.5 ± 0.5 mm in the study group and 2.1 ± 0.7 mm in the control group [mean difference, - 0.7 mm; 95% confidence interval (CI) - 1.1 to - 0.3; p = 0.003], showing superior accuracy of reconstruction for the patients with 3D-printed patient-specific surgical plates. Improved accuracy of reconstruction also was detected in terms of bilateral mandibular angles and bone grafts. Concerning the secondary end points, the accuracy of the osteotomy was similar in the two groups. No difference was found regarding intraoperative blood loss, total operative time, or length of hospital stay. CONCLUSIONS: This is the first study to prove that compared with conventional plates, 3D-printed patient-specific surgical plates improve the accuracy of oncologic head and neck reconstruction.

"Three-in-one" patient-specific surgical guides for simultaneous dental implants in fibula flap jaw reconstruction: A prospective case series.

BACKGROUND: Conventional freehand immediate placement of dental implants is technically challenging in the jaw reconstructive surgery. Computer-aided surgery might be the best solution, however, there has not been any standard approach to ensure the accuracy and efficiency of simultaneous dental implants in fibula flap jaw reconstruction. PURPOSE: We aim to evaluate the clinical outcome of simultaneous dental implant in fibula flap using the "three-in-one" patient-specific surgical guide (3-in-1-PSSG) in an open-label, prospective, single-arm, and single-center clinical trial. MATERIALS AND METHODS: A novel computer-aided designed and three-dimensional (3D) printed 3-in-1-PSSG, which contains functions of fibula segmentation, surgical plate positioning and implant placement, was used to facilitate the reconstructive surgery and simultaneous dental implant placement. The intraoperative success of dental implant placement, implant survival rate and accuracy of dental implant placement were reported. RESULTS: From November 2018 to June 2020, 15 consecutive patients with 48 dental implants were enrolled in this study. Fifteen 3-in-1-PSSGs were fabricated with a mean number of dental implants per guide of 3.2 ± 1.5. The intraoperative success rate of this approach was 14 out of 15. With an average follow-up period of 40 weeks, the overall implant survival rate was 83.3% (40/48). Eight implants were removed due to two fibula flap failures. The mean deviation at the implant platform and implant apex were 2.8 mm (interquartile range [IQR]: 1.9-3.4) and 3.2 mm (IQR: 2.0-4.6), and the angular deviation was 2.5° (IQR: 1.1-6.8). CONCLUSIONS: Our preliminary data indicated that the 3D printed 3-in-1-PSSG facilitated simultaneous dental implant in fibula flap jaw reconstruction with a favorable intraoperative success and short-term clinical outcome. It might be a viable alternative to allow one-step immediate oral rehabilitation in patients underwent jaw reconstruction with free flaps. Long-term results with a larger sample size are warranted.