Mao C

Applying computer techniques in maxillofacial reconstruction using a fibula flap: a messenger and an evaluation method.

While the application of computer-assisted maxillofacial surgery becomes increasingly popular, the translation from virtual models and surgical plans to actual bedside maneuvers and the evaluation of the repeatability of virtual planning remain to be major challenges. The objective of this study was to experiment the technique of using a resin template as a messenger in maxillofacial reconstruction involving a fibula flap. Another aim was to find a quantitative and objective method to evaluate the repeatability of preoperative planning. Seven patients who underwent maxillary or mandibular reconstruction were included in this study. The mean age was 25 years, and the mean follow-up period was 18.7 months. Virtual planning was carried out before surgery. A resin template was made according to the virtual design of bone graft through rapid prototyping technique and served as a guide when surgeons shaped the fibula flap during surgery. The repeatability of the virtual plan was evaluated based on the matching percentage between the actual postoperative model and the computer-generated outcome. All patients demonstrated satisfactory clinical outcomes. The mean repeatability was 87.5% within 1 mm and 96.5% within 2 mm in isolated bone graft. It was 71.4% within 1 mm and 89.9% within 2 mm in reconstructed mandible or maxilla. These results demonstrated that a resin template based on virtual plan and rapid prototyping technique is a reliable messenger to translate from computer modeling to bedside surgical procedures. The repeatability of a virtual plan can be easily and quantitatively evaluated through our three-dimensional differential analysis method.

Microvascular autologous transplantation of partial submandibular gland for severe keratoconjunctivitis sicca

Objective To evaluate the feasibility of microvascular autologous transplantation of partial submandibular gland (SMG) to prevent or reduce epiphora in severe keratoconjunctivitis sicca (KCS). Methods A total of 39 patients with KCS, covering 42 eyes, were randomised to undergo transplantation of partial or total SMG from January 2006 to December 2009. Clinical data of survival rate of transplanted SMG, ophthalmologic features of best-corrected visual acuity, Schirmer test results, break-up time (BUT) of tear film, fluorescence staining, incidence of postoperative epiphora and frequency of subsequent surgery were compared between two groups. Results Total SMG transplantation was performed in 22 eyes, and partial SMG transplantation was performed in the other 20 eyes. All transplanted SMGs survived. Microvascular crisis occurred in one case of partial SMG transplantation, but the gland survived after exploration to remove the venous thrombus. Obstruction of the ductal orifice in one case of partial SMG transplantation was resolved by reconstruction of the ductal orifice. Symptoms of dry eyes disappeared, and patients were able to discontinue use of artificial tears. Severe epiphora occurred in 6 eyes undergoing partial SMG transplantation and in 19 eyes undergoing total SMG transplantation (p<0.01). Surgical reduction was performed in 6 eyes undergoing partial SMG transplantation and 18 eyes undergoing total SMG transplantation (p<0.01). Conclusions Microvascular transplantation of partial SMG is feasible and effective for severe KCS and does not decrease the survival rate of transplanted SMG. For ample SMGs with normal function, transplantation of partial SMG alleviates the symptoms of dry eye and significantly reduces the incidence of severe postoperative epiphora.

Reconstruction of anophthalmic orbits and contracted eye sockets with microvascular radial forearm free flaps.

Purpose: To reconstruct the anophthalmic orbit using a microvascular radial forearm free flap in patients with significant volume loss and socket contracture after exenteration or enucleation. Methods: This is a retrospective observational case series of 22 subjects with acquired anophthalmic orbits after tumor resection or trauma: 14 patients with retinoblastoma who underwent enucleation followed by adjuvant radiation therapy and 8 patients with malignant orbital tumors or orbital trauma who underwent exenteration of the orbit. All patients had large orbital defects or severely contracted eye sockets. Patients underwent orbital reconstruction with implantation of a microvascular radial forearm free flap with or without placement of a hydroxyapatite sphere or conical implant. Results: All patients were followed for 6 months to 6 years. Long-term improvement of socket contracture, prosthesis fit, and cosmetic appearance of patients was observed. The prosthetic eyes were well fitted in the eye socket using this technique. Conclusions: Our results demonstrate successful functional and clinical outcomes for treatment of severe anophthalmic orbital syndrome using microvascular radial forearm free flaps. However, further prospective, long-term studies are recommended.

Primate mandibular reconstruction with prefabricated, vascularized tissue-engineered bone flaps and recombinant human bone morphogenetic protein-2 implanted in situ

Several studies have validated successful mandibular reconstruction with prefabricated tissue-engineered bone flaps and recombinant human bone morphogenetic protein-2 (rhBMP-2) implanted in situ. Whether rhBMP-2 applied with the prefabrication technique enables faster ossification of mandibular defects than rhBMP-2 applied in situ is unknown. We aimed to compare mandibular reconstruction with prefabricated, vascularized tissue-engineered bone flaps with rhBMP-2 and rhBMP-2 applied in situ in primates (Rhesus monkey). We also compared the use of the carriers demineralized freeze-dried bone allograft (DFDBA) and coralline hydroxyapatite (CHA) for applying rhBMP-2. After computed tomography of the monkey head, custom meshes were made, loaded with rhBMP-2-incorporated DFDBA or CHA, and implanted in the latissimus dorsi muscle. Meanwhile, contralateral segmental mandibular defects were created, and custom meshes loaded with DFDBA, CHA, or rhBMP-2-incooperated DFDBA and CHA were implanted in situ. Thirteen weeks later, the bone flaps with rhBMP-2-incorporated DFDBA or CHA were transferred to repair segmental mandibular defects. The meshes loaded with DFDBA or CHA alone showed no bone regeneration 13 weeks after implantation in latissimus dorsi muscle. Radiography, angiography and histological analysis were used to evaluate the repair and vascularization of the implant. Segmental mandibular defects were successfully restored with prefabricated bone flaps and rhBMP-2-incorporated CHA in situ, but other segmental mandibular defects remained with rhBMP-2-incorporated DFDBA, DFDBA and CHA in situ. Moreover, mandibles reconstructed with rhBMP-2-incorporated CHA bone flaps revealed more regenerated and homogeneous bone formation than did other reconstructions. The study suggested that the prefabrication technique induced better mandibular reconstruction and bone regeneration in quantity and quality.

Prevention of radiation-induced xerostomia by submandibular gland transfer.

This study was carried out for the purpose of evaluating the efficacy of submandibular gland transfer to prevent radiation‐induced xerostomia.

Clinical and Anatomic Study on the Ducts of the Submandibular and Sublingual Glands

PURPOSE To investigate the relationship between the ducts of the submandibular gland (SMG) and sublingual gland (SLG) and discuss its clinical application relating to SMG radiologic examinations and transfer. MATERIALS AND METHODS The microanatomy of the SMG and SLG was investigated by use of 30 adult cadavers through anatomic dissection by use of a microscope. The relationship between the SMG and SLG ducts was observed and recorded during operations of microvascular autologous SMG transfer in 63 cases of severe keratoconjunctivitis sicca. RESULTS There were 3 patterns of SLG and SMG duct anatomic variation: 1) The SMG and SLG have their own respective ducts that secrete separately at the orifices of the ducts in the floor of the mouth. 2) The SLG has a major duct that joins the duct of the SMG. 3) The SLG only has many fine ducts (7-15) that secrete in the floor of the mouth. CONCLUSIONS The anatomy of the ducts of the SMG and SLG is quite complicated. More attention should be paid to the anatomy of the ducts during surgery or imaging procedures related to the SMG.

Application of 99mTc-Pertechnetate Scintigraphy to Microvascular Autologous Transplantation of the Submandibular Gland in Patients with Severe Keratoconjunctivitis Sicca

Our objective was to evaluate the role of 99mTc-pertechnetate scintigraphy on microvascular autologous transplantation of the submandibular gland in patients with severe keratoconjunctivitis sicca (KCS). Methods: 99mTc-Pertechnetate scintigraphy was performed on 106 patients with severe KCS. The patients were examined before surgery and at 1 wk and 3 mo afterward using a standardized protocol that included static scintigrams, time–activity curves, and delayed scintigrams to check the function and secretion of the major salivary glands. The scintigraphic findings were assessed visually. When possible, the scintigraphic findings were compared with the clinical appearance of the transplanted gland. Results: The function of all 4 major salivary glands was almost completely lost in 10 patients, indicating that these patients were not suitable for transplantation. The other 96 patients were treated by autologous transplantation of the submandibular gland. In 14 patients, the function of the major salivary glands was below normal. One patients scintigram, obtained on the second day after surgery, showed no uptake of 99mTc-pertechnetate in the transplanted gland. Surgical exploration showed embolism of the artery of the transplanted gland. Scintigraphy was performed 1 wk after surgery in 90 patients. There was no uptake of 99mTc-pertechnetate in the temporal region in 8 patients, indicating that the glands were not revascularized. Scintigraphy showed obvious uptake of 99mTc-pertechnetate in the temporal region of the other 82 patients, indicating that the transplanted glands were viable. At more than 3 mo after surgery, scintigraphy was again performed on 30 patients. Scintigraphy after a 120-min delay showed that 99mTc-pertechnetate drained into the orbit through the duct of the transplanted gland in 26 patients. However, no secretion into the orbit was found in 4 patients, indicating obstruction of the duct. Conclusion: Scintigraphy plays an important role in microvascular autologous transplantation of the submandibular gland in patients with severe KCS. Scintigraphy can be used to select patients and donor glands, to evaluate the viability of the graft, and to check the patency of Whartons duct of the transplanted gland.

Supraomohyoid neck dissection and modified radical neck dissection for clinically node-negative oral squamous cell carcinoma: a prospective study of prognosis, complications and quality of life.

BACKGROUND To assess the prognosis and morbidity between supraomohyoid neck dissection (SOND) and modified radical neck dissection (MRND) for oral squamous cell carcinoma (OSCC) in patients with a clinically node-negative neck (cN0). PATIENTS AND METHODS This prospective randomized study began in June 1999, and patient accrual concluded in May 2010. The cN0 neck was confirmed on clinical palpation by senior doctors. Ultimately, there were 322 patients recruited into the study. RESULTS Patient demographics were well balanced between the two groups. There were 10 patients in the SOND group and 21 patients in the MRND group who developed nodal recurrence without associated local recurrence or distant metastasis. The 3-year neck control rate (NCR) rate was 92.6% for the SOND group and 87.5% for the MRND group (in favor of SOND, P = 0.108). There was no significant difference between the SOND group and the MRND group in the 3-year disease-specific survival (DSS) rate (79.0% vs. 76.9%, P = 0.659). Importantly, there were significantly fewer complications in the SOND group compared with the MRND group (13.0% vs. 21.9%, P = 0.040). The disease-free survivors in the SOND group also reported better pain relief (P = 0.013) and shoulder function (P < 0.001) than those in the MRND group one year after treatment. CONCLUSIONS We recommend SOND as a priority treatment for cN0 OSCC patients.

Microanatomic study of the vascular and duct system of the submandibular gland.

PURPOSE Autologous microvascular submandibular gland (SMG) transfer is an effective treatment for severe keratoconjunctivitis sicca (KCS). However, epiphora (excessive tear secretion) may occur after the successful transfer of whole submandibular gland because tear secretion level is closely related to the size of the transferred gland. The aim of this study was to investigate the microanatomy of SMG to explore the possibility of partial SMG transfer to prevent postoperative epiphora. MATERIALS AND METHODS Sixty intact and histologically normal human SMGs from patients with benign tumor of the mandible who underwent vascularized mandibular reconstruction and removal of the SMG for anastomosis of the blood vessels were included in the study. SMGs were perfused with methacrylate to form resin casts of blood vessels and ducts. The length and diameter of the blood vessels and ducts in the casts were measured using a sliding caliper. The numbers of lobules, distribution of arteries, veins, and ducts, as well as the relationship among them, were analyzed. RESULTS The resin cast of the gland showed a treelike structure, with the vessels gradually dividing into multiple branches. The arteries, veins, and ducts run in parallel and were roughly divided into 3 levels: from the stem extending into the main branches (level I), into the narrower secondary branches (level II), and then the secondary branches subsequently divided into terminal branches (level III). The structures of the blood vessels and ducts were similar at each level in the lobules. In the vein casts, communicating vessels were found between the anterior facial vein and the concomitant vein of the facial artery. CONCLUSION The characteristic treelike structure of the SMG vascular and ductal system may provide useful information for partial gland transfers.

Cervical metastasis of maxillary squamous cell carcinoma.

A retrospective study of maxillary squamous cell carcinoma (SCC) patients attending a department of oral and maxillofacial surgery was performed for the period 2000-2010. The clinical information of 100 cases treated during this period was acquired and analyzed. Patient survival was calculated using the Kaplan-Meier method. For these 100 cases, the total metastatic rate was 34.0% and occult metastatic rate was 27.5%. Positive lymph nodes were mostly detected at levels I-III. There was no significant difference in metastatic rate between the primary sites of maxillary gingiva and hard palate. Tumours involving the gingival-buccal sulcus presented a significantly higher risk of metastasis. Advanced stage (T3/4) was significantly correlated with a higher metastasis rate. The pathological grade also showed a significant relationship with metastasis. Twenty-four patients presented regional recurrence. Elective neck dissection could significantly reduce the recurrence rate. The overall 3-year and 5-year survival rates were 66.3% and 56.7%, respectively. Both the T and the N stages had a significant impact on survival rates. Selective neck dissection from level I to III is recommended for T3/4 stage cN0 patients, especially those with gingival-buccal sulcus involvement.