Animal models of vertical bone augmentation (Review).

Vertical bone augmentation is an important challenge in dental implantology. Existing vertical bone augmentation techniques, along with bone grafting materials, have achieved certain clinical progress but continue to have numerous limitations. In order to evaluate the possibility of using biomaterials to develop bone substitutes, medical devices and/or new bone grafting techniques for vertical bone augmentation, it is essential to establish clinically relevant animal models to investigate their biocompatibility, mechanical properties, applicability and safety. The present review discusses recent animal experiments related to vertical bone augmentation. In addition, surgical protocols for establishing relevant preclinical models with various animal species were reviewed. The present study aims to provide guidance for selecting experimental animal models of vertical bone augmentation.

Intraparotid facial nerve schwannoma: a 17-year, single-institution experience of diagnosis and management.

BACKGROUND: Intraparotid facial nerve schwannoma (IFNS) is rare and its definite preoperative diagnosis is challenging. OBJECTIVE: To improve available knowledge regarding the diagnosis of IFNS and to suggest an appropriate treatment plan. MATERIAL AND METHODS: We retrospectively analyzed medical records of IFNS patients at our hospital. Inclusion criteria were surgery (from January 2000, to December 2016) for a parotid mass, pathologically diagnosed as a schwannoma. RESULTS: The study included 42 eligible patients who had undergone tumor resection from 5977 parotid tumor patients. Mostly presented hard-textured (18/39) or medium-textured (15/39), with limited mobility (21/39) mass (three tumors were not palpable). Their facial nerve function outcomes were House-Brackmann Grade I (n = 14), Grade II (n = 7), Grade III (n = 11), Grade IV (n = 5), Grade V (n = 3), and Grade VI (n = 2). Significant differences were noted in results based on different surgical methods used (p = .000) and tumor involvement (p = .002). CONCLUSIONS AND SIGNIFICANCE: A hard-textured tumor with limited mobility mass in the parotid gland should prompt the diagnosis of a schwannoma. Tumors involving main trunk usually lead to unsatisfactory facial nerve outcomes. Facial nerve preservation should always be essential, and stripping surgery or intracapsular enucleation could be the preferred surgical methods of choice.

Enhanced bone regeneration using an insulin-loaded nano-hydroxyapatite/collagen/PLGA composite scaffold.

Insulin is widely considered as a classical hormone and drug in maintaining energy and glucose homeostasis. Recently, insulin has been increasingly recognized as an indispensable factor for osteogenesis and bone turnover, but its applications in bone regeneration have been restricted because of the short periods of activity and uncontrolled release. In this study, we incorporated insulin-loaded poly lactic-co-glycolic-acid (PLGA) nanospheres into nano-hydroxyapatite/collagen (nHAC) scaffolds and investigated the bioactivity of the composite scaffolds in vitro and in vivo. Bioactive insulin was successfully released from the nanospheres within the scaffold, and the release kinetics of insulin could be efficiently controlled by uniform-sized nanospheres. The physical characterizations of the composite scaffolds demonstrated that incorporation of nanospheres in nHAC scaffolds using this method did not significantly change the porosity, pore diameters, and compressive strengths of nHAC. In vitro, the insulin-loaded nHAC/PLGA composite scaffolds possessed favorable biological function for bone marrow mesenchymal stem cells adhesion and proliferation, as well as the differentiation into osteoblasts. In vivo, the optimized bone regenerative capability of this composite scaffold was confirmed in rabbit mandible critical size defects. These results demonstrated successful development of a functional insulin-PLGA-nHAC composite scaffold that enhances the bone regeneration capability of nHAC.

Preliminary clinic study on computer assisted mandibular reconstruction: the positive role of surgical navigation technique.

BACKGROUND: The objectives of the present study were to investigate the reliability and outcomes of computer-assisted techniques in mandibular reconstruction with a fibula flap and verify whether the surgical navigation system was feasible in mandible reconstructive surgery. METHODS: Eight cases were enrolled in the computer assisted surgery (CAS) group and 14 cases in the traditional group. The shaping and fixation of the fibula grafts were guided by computer assisted techniques, which could be monitored with the BrainLAB surgical navigation system. The variation of mandible configuration was evaluated by CT measurement in the Mimics software, including the variation of length, width, height and gonial angle of the mandible. The 3D facial soft tissue alteration was also analyzed in 3D chromatogram by Geomagic software. RESULTS: All 22 fibula flaps survived. The mandibular configurations and facial contours had a better clinic result in the CAS group. The length, width, height and gonial angle of the reconstructive mandible were more similar to the original one. The Wilcoxon rank sum test analysis suggested significant differences in the measurements. The chromatographic analysis also visually showed superiority over the traditional group. CONCLUSIONS: The computer assisted surgical navigation method used in mandibular reconstruction is feasible and precise for clinical application. The contour of the reconstructed mandible and facial symmetry are improved with computer techniques.

Fibular free flap reconstruction for the management of advanced bilateral mandibular osteoradionecrosis.

Fibular osteoseptocutaneous flap has been widely used for unilateral mandibular reconstruction. However, reports about the effects of fibular osteoseptocutaneous flap for the reconstruction of bilateral mandibular defects are limited. In this study, we used free vascularized fibular flaps to successfully manage bilateral mandibular osteoradionecrosis(ORN) in 5 patients. Functional aspects were evaluated during the reconstruction process. All 5 patients had bilateral refractory ORN of the mandible and underwent radical resection between 2003 and 2011. The reconstruction surgery was performed in 2 stages using 2 free fibular flaps in 3 patients. In the other 2 patients, reconstruction was performed in a single stage using 2 separate flaps prepared from a single fibula. All patients had a healthy mandibular symphysis and meniscus of the temporomandibular joint, and these structures were preserved during the reconstruction.Of the 10 defects involving the mandible sides, 9 were successfully reconstructed. One microvascular composite flap failed because of radiation injury to the arterial endothelium at the recipient site. After the treatments, all patients had good esthetic and functional outcomes. Preoperative clinical features such as trismus and dysphagia were also markedly improved. Our surgical method may be an effective alternative for the clinical management of advanced bilateral mandibular ORN.

Preoperative percutaneous nerve mapping of the mandibular marginal branch of the facial nerve.

OBJECTIVE: In this study, we introduce a reliable method for mapping the location of the mandibular marginal branch of the facial nerve. The utility of preoperative percutaneous mandibular marginal branch mapping and continuous intraoperative nerve monitoring during operation with a submandibular approach is reported. MATERIALS AND METHODS: The mapping technique was performed in 40 patients. Electromyography surface electrodes were placed on the orbicularis oris muscles. A modified bipolar probe with an adjustable distance between the 2 tips was used to apply surface stimulation at a frequency of 1 Hz to 2 Hz. The stimulating current most frequently used was 5.0 mA to 5.5 mA. By moving the electrode at right angles across the suspected path of the nerve around the marginal border of the mandible, 4 to 5 points were marked and connected, where the orbicularis oris contracted and the action potential was evoked. After general anesthesia, the mapping path was verified using needle electrodes with different needle-to-nerve distances. RESULTS: The nerve could be mapped preoperatively in all patients and were protected in 39 patients. The thresholds of the needle electrode on the mapping path were at or below 0.5 mA, verifying the accuracy of mapping. CONCLUSIONS: Preoperative percutaneous nerve mapping was a precise method of identifying the location of the nerve and could protect the nerve from accidental injury.

Use of sensory and motor action potentials to identify the position of trigeminal nerve divisions for radiofrequency thermocoagulation.

OBJECT: The objective of this study was to develop an electrophysiological method for intraoperative localization of the trigeminal nerve branches during radiofrequency thermocoagulation (RFTC). METHODS: Twenty-three patients who were scheduled to undergo RFTC were included. The trigeminal nerve root was stimulated through the foramen ovale using the radiofrequency cannula. Antidromic responses were recorded from the target division through supraorbital, infraorbital, and mental foramina electrodes, and an additional electrode at the masseter muscle. Sensory and motor action responses, as well as verbal and masseter contraction responses, were recorded and correlated. RESULTS: The antidromic responses were easily recorded in the target division in all 23 patients, and they were invariably correlated with the patient's verbal responses. The potentials were recorded successively from V1 to V3. The amplitude in each division before and after RFTC showed little difference in response to electrical stimulation with the same current. The motor trigeminal nerve action potentials were recorded in 10 patients; 7 of these patients had postoperative masseter muscle weakness, while the remaining 3 had normal masseter muscle function. Potentials with low amplitudes were usually obtained from neighboring divisions, but no unexpected denervation of any branches was observed. All the patients experienced immediate pain relief after the procedure. CONCLUSIONS: This technique is sensitive and easy to apply. The sensory and motor potentials matched the verbal responses and the complications. Although it cannot completely substitute for the patient's verbal response, this approach is helpful in uncooperative patients, and it predicts and reduces the incidence of masseter muscle weakness. The use of these complementary techniques could increase the chances of treatment success.

[Electromyographic monitoring of facial nerve during parotid surgery].

OBJECTIVE: To analyze the benefits of facial nerve electromyographic monitoring during parotid tumor surgery. METHODS: In the study, 92 patients with parotid tumor who underwent surgery were surveyed. The study group consisted of 46 patients who underwent intraoperative electromyographic monitoring, and 46 patients served as the control group. The incidence of postoperative facial nerve weakness and the operation time were recorded. RESULTS: In the primary parotid tumor resection,the operation time of the study group (6 cases)was (50.0 ± 9.1) min, that of control group (7 cases) was (42.9 ± 5.2) min (P = 0.064) when the facial nerve needed no dissecting; the operation time of the study group (32 cases)was (74.7 ± 28.0) min, that of control group (33 cases) was (75.6 ± 29.8) min (P = 0.893) when the facial nerve needed dissecting. For the patients with revision surgery, the mean operation time in the study group [(117.5 ± 37.8) min] was significantly lower than that of the control group [(175.0 ± 47.8) min], P < 0.05. In the study group, 8 patients suffered from postoperative facial nerve weakness because of tumor characteristics; in the control group, 6 patients suffered from postoperative facial nerve weakness, with 4 cases because of tumor characteristic, and 2 cases because of operator error. CONCLUSION: The results suggest that continuous electromyographic monitoring of facial nerve during parotidectomy reduces the mean operation time in patients with revision surgery, but not the incidence of postoperative facial paralysis.

[Clinical analysis of 182 cases with facial nerve injury].

OBJECTIVE: To investigate the recovery patterns and the influencing factors of facial nerve injury in maxillofacial surgery by retrospective analysis of a serial clinical data. METHODS: A total of 182 patients with facial nerve injury were reviewed. The cause of injury, the initial facial nerve function after trauma, the treatment, the initial recovery time of facial nerve function and the total recovery time were recorded. The factors that influenced the outcome of facial nerve function were analyzed. RESULTS: The facial nerve branch injury was common in maxillofacial injury. The injury pattern, location, age and reconstruction time all had effects on the function recovery of the facial nerve. Within 6 months, 45 of 49 (92%) anatomic injured patients completely recovered in 6 months; 53 of 59 patients (90%) began to recover when nerve had been ruptured. In 12 months, 33 of 35 patients (94%) after nerve anastomosed and 5 of 8 patients (62%) with nerve transplantation got complete recovery. CONCLUSIONS: Preserving the facial nerve during surgery is very important. If the facial nerve is injured, reconstructive surgery should be applied as soon as possible.