Si-en Zhang

Mandible Reconstruction Assisted by Preoperative Simulation and Transferring Templates: Cadaveric Study of Accuracy

PURPOSE In this study we tried to define tumor resection, fibula cutting, and positioning by surgical templates to perform the mandible reconstruction surgery according to the preoperative simulation. The accuracy was evaluated through cadaveric surgery. MATERIALS AND METHODS Five cadaveric mandibles and fibulas were obtained. Preoperative surgical simulation was performed. Surgical templates that defined tumor resection, fibula cutting, and positioning were designed and fabricated. Translation, angular deviation, and rotation of bone grafts, as well as translation of condyles, were measured. RESULTS The reconstructed mandibles showed high similarity to the surgical planning. The mean translation, angular deviation, and rotation of fibula segments of the reconstructed mandibles were 1.35 ± 0.86 mm, 3.36° ± 1.86°, and 8.13° ± 5.35°, respectively. In the mandible remnants, the translation of condyles was measured, with a mean of 1.39 ± 0.66 mm. CONCLUSIONS Our method of defining the tumor resection, fibula cutting, and positioning by surgical templates was accurate enough for mandible reconstruction surgery.

Mandibular Reconstruction Assisted by Preoperative Simulation and Accurate Transferring Templates: Preliminary Report of Clinical Application

PURPOSE This study investigated the application of a computer-aided design and manufacturing technique of defining tumor resection, fibula cutting, and positioning by surgical templates in mandibular reconstructive surgery. MATERIALS AND METHODS Four patients who required mandibulectomy and simultaneous reconstruction were enrolled in this study. Preoperative surgical simulation was performed. The surgical templates that defined tumor resection, fibula cutting, and positioning were designed and fabricated. RESULTS The surgeries were performed to the preoperative plan. All flaps survived. Superimposition of the postoperative image and the preoperative plan showed a satisfactory surgical accuracy. CONCLUSIONS This method of defining tumor resection, fibula cutting, and positioning by surgical templates was accurate enough for mandibular reconstructive surgery.

Zoledronate suppressed angiogenesis and osteogenesis by inhibiting osteoclasts formation and secretion of PDGF-BB

Purpose Bisphosphonates related osteonecrosis of jaw (BRONJ) is a severe complication of systemic BPs administration, the mechanism of which is still unclarified. Recently, platelet-derived growth factor-BB (PDGF-BB) secreted by preosteoclasts was reported to promote angiogenesis and osteogenesis. This study aimed to clarify whether bisphosphonates suppressed preosteoclasts releasing PDGF-BB, and whether the suppression harmed coupling of angiogenesis and osteogenesis, which could contribute to BRONJ manifestation. Methods and results Zoledronate significantly inhibited osteoclast formation by tartrate-resistant acid phosphatase (TRAP) staining and PDGF-BB secretion tested by ELISA. In line with decreasing secretion of PDGF-BB by preosteoclasts exposed to zoledronate, conditioned medium (CM) from the cells significantly induced less migration of endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs) compared to CM from unexposed preosteoclasts. Meanwhile, angiogenic function of EPCs and osteoblastic differentiation of MSCs also declined when culturing with CM from preosteoclasts treated by zoledronate (PZ-CM), evidenced by tube formation assay of EPCs and alkaline phosphatase activity of MSCs. Western blot assay showed that the expression of VEGF in EPCs and OCN, RUNX2 in MSCs declined when culturing with PZ-CM compared to CM from preostoeclasts without exposure of zoledronate. Conclusion Our study found that zoledronate was able to suppress preosteoclasts releasing PDGF-BB, resulting in suppression of angiogenesis and osteogenesis. Our study may partly contributed to the mechanism of BRONJ.

Maxillary reconstruction assisted by preoperative planning and accurate surgical templates

OBJECTIVE Surgical reconstruction of maxilla is technically challenging and time consuming. The study reports a new method of maxillary reconstruction assisted by preoperative surgical simulation and accurate transferring templates. STUDY DESIGN Six patients requiring maxillary reconstruction were enrolled in our study. Templates of maxillary resection, fibula cutting, and positioning were designed based on computed tomography (CT) data and fabricated via rapid prototyping technique. Resection, fibula cutting, and positioning were performed according to the templates. Accuracy was evaluated by measuring deviation, performed by superimposing preoperative planning and postoperative maxilla. RESULTS The surgery was performed faithfully to the preoperative planning. The facial contour was satisfied. Postoperative CT scans showed high accuracy of the surgical implementation. The average central point deviation, maximum deviation, and rotation were 0.58 mm, 1.53 mm, and 6.0°, respectively. CONCLUSION With preoperative surgical simulation and templates, maxillary reconstruction can be performed accurately.

Reinnervated nerves contribute to the secretion function and regeneration of denervated submandibular glands in rabbits

This study aimed to investigate the contribution of redistributed nerves in the secretory function and regeneration of a denervated submandibular gland (SMG). The postganglionic parasympathetic and sympathetic denervated SMGs of rabbits were wrapped in polyester or acellular dermal matrices to block nerve regeneration either partially or completely. Submandibular glands were removed 4, 8, 16, and 24 wk after the operation and examined histologically. Furthermore, the aquaporin-5 (AQP5), muscarinic-3 (M3), and β1-adrenergic receptors were evaluated by immunofluorescence and western blot analysis. After denervation, salivary flow was decreased and acinar cells were atrophic, and the expression levels of the M3, β1-adrenergic, and AQP5 receptors were decreased. However, both impaired secretion function and atrophic parenchyma were gradually ameliorated with the growing redistribution of parasympathetic and sympathetic nerves. Apoptosis was markedly inhibited and expression of the M3, β1-adrenergic, and AQP5 receptors was increased after reinnervation. In contrast, SMGs without reinnervated nerves maintained hyposecretion and atrophic parenchyma. In conclusion, reinnervated nerves in a rabbits denervated SMG played an important role in the secretion function and regeneration of SMGs via up-regulation of the expression of neurotransmitter receptors and AQP5.

miRNA‑335 and miRNA‑182 affect the occurrence of tongue squamous cell carcinoma by targeting survivin

The aim of the present study was to characterize the roles of two microRNAs (miRs) that have been reported to be differentially expressed in tongue squamous cell carcinoma (TSCC), miR-335 and miR-182. In total, 20 tumor tissue samples and 20 corresponding adjacent non-cancerous samples were collected from patients with TSCC to measure the expression of miR-335 and miR-182 and the potential shared target of these miRs, survivin, using reverse transcription-quantitative polymerase chain reaction and western blotting. In the TSCC tissue samples, significantly decreased expression of the two miRs and increased expression of survivin were detected compared with adjacent non-cancerous controls. Subsequently, it was confirmed that survivin was the target gene of miR-335 and miR-182 using a luciferase assay in TSCC cells. In order to examine the function of miR-335 and miR-182 in the development of TSCC, TSCC cells were transiently transfected with the mimics of the two miRs, and it was confirmed that the introduction of miR-335 and miR-182 to cells suppressed the expression of survivin and markedly inhibited the proliferation of the TSCC cells. Furthermore, miR-335 and miR-182 were found to induce cell cycle arrest by suppressing the expression of survivin. The present study revealed a negative regulatory role of miR-335 and miR-182 in the proliferation of TSCC cells by targeting survivin, and miR-335 and miR-182 may be novel therapeutic targets for the treatment of TSCC.

Neck observation versus elective neck dissection in management of clinical T1/2N0 oral squamous cell carcinoma: a retrospective study of 232 patients

Objective The management of early-stage (cT1/2N0) oral squamous cell carcinoma (OSCC) remains a controversial issue. The aim of this study was to compare the clinical outcomes of neck observation (OBS) and elective neck dissection (END) in treating patients with cT1/2N0 OSCC. Methods A total of 232 patients with cT1/2N0 OSCC were included in this retrospective study. Of these patients, 181 were treated with END and 51 with OBS. The survival curves of 5-year overall survival (OS), disease-specific survival (DSS), and recurrence-free survival (RFS) rates were plotted using the Kaplan-Meier method for each group, and compared using the Log-rank test. Results There was no significant difference in 5-year OS and DSS rates between END and OBS groups (OS: 89.0% vs. 88.2%, P=0.906; DSS: 92.3% vs. 92.2%, P=0.998). However, the END group had a higher 5-year RFS rate than the OBS group (90.1% vs. 76.5%, P=0.009). Patients with occult metastases in OBS group (7/51) had similar 5-year OS rate (57.1% vs. 64.1%, P=0.839) and DSS rate (71.4% vs. 74.4%, P=0.982) to those in END group (39/181). In the regional recurrence patients, the 5-year OS rate (57.1% vs. 11.1%, P=0.011) and DSS rate (71.4% vs. 22.2%, P=0.022) in OBS group (7/51) were higher than those in END group (9/181). Conclusions The results indicated that OBS policy could obtain the same 5-year OS and DSS as END. Under close follow-up, OBS policy may be an available treatment option for patients with clinical T1/2N0 OSCC.

Long-term outcomes of endoscopic neck dissection in the treatment of early-stage oral cancer: a pilot study

OBJECTIVE This study aimed to investigate the feasibility and safety of endoscopic neck dissection in the treatment of early-stage oral cancer and to evaluate the long-term clinical outcomes. STUDY DESIGN Six patients with early-stage oral cancer were enrolled in this pilot study from December 2006 to May 2007. All the patients underwent endoscopic selective neck dissection (levels I-IV) of the ipsilateral neck and partial glossectomy or hemiglossectomy as the primary treatment. RESULTS All endoscopic procedures were successfully performed, with important neck structures identified and preserved. All the patients survived with no persistent or recurrent disease during the 76- to 83-month follow-up. CONCLUSIONS Our preliminary results indicated that endoscopic neck dissection is a technically feasible and safe technique for treating early-stage oral cancer. The oncologic indications and validation should be further confirmed in patients with clinically positive neck lymph nodes in a future study.

Elevated hydrostatic pressure promotes ameloblastoma cell invasion through upregulation of MMP-2 and MMP-9 expression via Wnt/β-catenin signalling

BACKGROUND The process of marsupialization involves the release of intracystic pressure and the fluid contained within. Marsupialization of cystic ameloblastoma is controversial; therefore, we investigated how hydrostatic pressure influences biological behaviours of ameloblastoma cells and its underlying mechanisms. MATERIALS AND METHODS An ameloblastoma epithelial cell line, hTERT+ -AM, was exposed to different hydrostatic pressures with or without Dickkopf-related protein 1 (also known as DKK), a canonical Wnt signalling pathway inhibitor. A CCK-8 assay, a monolayer wound assay, and a Transwell assay were used to determine cell proliferation, migration and invasion, respectively. qRT-PCR and Western blot were used to detect expression of MMP-2, MMP-9, RANKL and other downstream targets of Wnt signalling. RESULTS Elevated hydrostatic pressure promoted migration and invasion of ameloblastoma cells, but inhibited proliferation. Expression of MMP-2, MMP-9, LEF-1, cyclin D1, c-Jun and c-Myc was significantly upregulated under elevated hydrostatic pressure, and these effects could be abolished by DKK1. Expression of RANKL, which is thought to be a downstream target of Wnt signalling, did not significantly change under elevated hydrostatic pressure. CONCLUSIONS This study indicates that elevated hydrostatic pressure promotes the migration and invasion of ameloblastoma cells by activating the Wnt/β-catenin pathway, thereby increasing expression of MMP-2, MMP-9 and other Wnt signalling downstream targets. This suggests that marsupialization may reduce invasiveness and reverse the bone resorption process by lowering intracystic hydrostatic pressure in cystic ameloblastoma.

Use of medial upper arm free flap in oral cavity reconstruction: a preliminary study

The medial upper arm has previously been proposed as a potential free flap donor site, but the clinical application of such flaps in head and neck reconstruction has not been popular. The preliminary results of the clinical application of medial upper arm free flaps in oral cavity reconstruction are reported here. Five patients with oral cancer underwent surgical resection and neck dissection, with simultaneous reconstruction using a medial upper arm free flap. Functional outcomes were investigated using the University of Washington Quality of Life Questionnaire. Sensory-motor functions of the upper arm donor site were recorded before and after surgery. Four flaps were successfully transferred. One flap was abandoned during surgery because of a lack of perforators, and a forearm flap was used instead. All patients survived without loco-regional recurrence or distant metastasis. Functional outcomes, especially swallowing and speech, were satisfactory. The donor site scar was well hidden, with no functional impairment. This initial experience shows that the medial upper arm free flap represents an alternative perforator flap for oral cavity microsurgical reconstruction. The well-hidden scar and better texture match compared with other flaps make it suitable for oral cavity reconstruction.