Alveolar ridge preservation of two-wall bone defects using mineralized dentin matrix: An experimental pre-clinical study.

OBJECTIVES: To study bone healing of two-wall bone defects after alveolar ridge preservation using mineralized dentin matrix. MATERIALS AND METHODS: After distal roots extraction of second and fourth premolars (P2, P4) on one lateral mandible in 12 beagles, two-wall bone defects (5 × 5 × 5 mm) were surgically created distally to the remaining mesial roots of P2 and P4. A total of 24 sites were randomly allocated to three groups (implant material- time of execution): mineralized dentin matrix (MDM)-3 m (MDM + collagen membrane; 3 months), MDM-6 m (MDM particles + collagen membrane; 6 months), and C-6 m (collagen membrane only; 6 months). Clinical, radiographic, digital, and histological examinations were performed 3 and 6 months after surgery. RESULTS: The bone healing in MDM groups were better compared to Control group (volume of bone regenerated in total: 25.12 mm3 vs. 13.30 mm3, p = .046; trabecular volume/total volume: 58.84% vs. 39.18%, p = .001; new bone formation rate: 44.13% vs. 31.88%, p = .047). Vertically, the radiological bone level of bone defect in MDM-6 m group was higher than that in C-6 m group (vertical height of bone defect: 1.55 mm vs. 2.74 mm, p = .018). Horizontally, no significant differences in buccolingual bone width were found between MDM and C groups at any time or at any level below the alveolar ridge. The percentages of remaining MDM were <1% in both MDM-3 m and MDM-6 m groups. CONCLUSIONS: MDM improved bone healing of two-wall bone defects and might be considered as a socket fill material used following tooth extraction.

Long-term result of 125 I seed brachytherapy for pediatric desmoid tumor in the head and neck.

BACKGROUND: Desmoid tumor (DT) is rare and challenging, often affects the head and neck (HN) region in children, and its appropriate treatments are under-discussed. This study aimed to retrospectively evaluate the long-term effectiveness and safety of 125 I seed brachytherapy for pediatric DT in HN. PROCEDURE: Seven pediatric patients with a median age of three years who suffered from DT in HN treated with 125 I brachytherapy from January 2008 to June 2018 were included. Among these, five underwent sole brachytherapy and the others combined with surgery under prescription doses ranging from 10,000 to 12,000 cGy. The rate of local control (LC), complete response (CR), and partial response (PR) was calculated after evaluation by radiological and pathological means. Radiation-associated toxicities were also evaluated. RESULTS: The LC rate was 7/7 during the follow-up time ranging from 43 to 135 months and with a mean of 57 months. No recurrent lesion was found in the patients receiving surgery combined with brachytherapy. In patients treated with sole brachytherapy, the radiological PR rate and CR rate were 4/5 and 1/5, respectively. In those reaching radiological PR, 3/4 were pathological CR. Slight acute radiation-associated toxicities were observed in all patients, and no late or severe acute toxicity was observed. CONCLUSION: 125 I brachytherapy is effective and safe in the management of pediatric DT in HN as the sole modality or combined with surgery in the long term.

Vascularized Free Fibular Flap in Oral and Maxillofacial Reconstruction: A 20-year Experience at a Single Institution Using 2640 Flaps.

BACKGROUND: This retrospective study reviewed all patients who underwent oral and maxillofacial reconstruction with fibular flaps in the last 2 decades at a single hospital. MATERIALS AND METHODS: We reviewed all patients with fibular flaps from 1999 to 2018. The following data were collected: sex; age; reconstruction region; diagnosis; the number of days spent in the hospital after surgery; time spent using a tourniquet for harvesting a fibula flap; vessels at the recipient site; the prevalence of unplanned reoperations; the prevalence of flap failure; history of preoperative radiotherapy; virtual surgical planning; segments of the fibula. RESULTS: In total, 2640 patients were included. The mean age was 45.5 years. The most prevalent region of reconstruction was the mandible (n=2347, 88.9%). The most common diagnosis was squamous cell carcinoma (n=1057, 40.0%). The mean number of days spent in the hospital after surgery decreased year-by-year from 18.3 days to 10.4 days. The first choice of recipient artery was the facial artery (n=1643, 62.2%) and that of the recipient vein was the external jugular vein (n=1196, 45.3%). The prevalence of surgical success was 97.6%. Prevalence of unplanned reoperations was 7.5%. CONCLUSIONS: The fibular flap was a good choice for oral and maxillofacial bony reconstruction in most cases.

Endoscopic visualization of the inferior alveolar nerve associated with somatosensory changes after impacted mandibular third molar extraction.

The aim of this study is to assess the relationship between somatosensory functional changes and inferior alveolar nerve (IAN) exposure after impacted mandibular third molars (M3M) removal. We recruited 35 patients who underwent impacted M3M extraction near the IAN. The M3Ms were extracted by combined endoscopy, piezosurgery, and contra-angle high-speed turbine handpiece. All IAN canal perforations and exposed regions were recorded and measured by endoscopy after extraction and on cone-beam computed tomography (CBCT) images before extraction. The patients were followed up 1, 7, and 35 days after surgery. A standardized quantitative sensory testing (QST) battery was performed on the lower lip skin. All of 35 cases had exposed IAN on CBCT images, 5 of which had no exposed IAN under endoscopy. For the other 30 cases, the endoscopy-measured IAN length and width were shorter than the CBCT measurements (P < 0.001). The warm and mechanical detection thresholds (MDT) on the operation side were significantly higher than the contralateral side after surgery (P < 0.05). Thermal sensory limen, MDT, and cold pain threshold were strongly correlated with the exposed IAN length and MDT also with the exposed IAN width one day after surgery. In conclusion, it was found that not all exposed IAN in CBCT images were real exposure after surgery. The intraoperative exposed IAN endoscopic measurements were smaller than by CBCT and strongly correlated with some QST parameters.

Anti-angiogenic drug aggravates the degree of anti-resorptive drug-based medication-related osteonecrosis of the jaw by impairing the proliferation and migration function of gingival fibroblasts.

BACKGROUND: Long-term use of anti-resorptive or anti-angiogenic drugs in cancer patients with odontogenic infections may lead to medication-related osteonecrosis of the jaw (MRONJ). This study investigated whether anti-angiogenic agents aggravate MRONJ occurrence in anti-resorptive-treated patients. METHODS: The clinical stage and jawbone exposure of MRONJ patients caused by different drug regimens were analyzed to ascertain the aggravation effect of anti-angiogenic drugs on anti-resorptive drug-based MRONJ. Next, a periodontitis mice model was established, and tooth extraction was performed after administering anti-resorptive and/or anti-angiogenic drugs; the imaging and histological change of the extraction socket were observed. Moreover, the cell function of gingival fibroblasts was analyzed after the treatment with anti-resorptive and/or anti-angiogenic drugs in order to evaluate their effect on the gingival tissue healing of the extraction socket. RESULTS: Patients treated with anti-angiogenic and anti-resorptive drugs had an advanced clinical stage and a bigger proportion of necrotic jawbone exposure compared to patients treated with anti-resorptive drugs alone. In vivo study further indicated a greater loss of mucosa tissue coverage above the tooth extraction in mice treated with sunitinib (Suti) + zoledronate (Zole) group (7/10) vs. Zole group (3/10) and Suti group (1/10). Micro-computed tomography (CT) and histological data showed that the new bone formation in the extraction socket was lower in Suti + Zole and Zole groups vs. Suti and control groups. In vitro data showed that the anti-angiogenic drugs had a stronger inhibitory ability on the proliferation and migration function of gingival fibroblasts than anti-resorptive drugs, and the inhibitory effect was obviously enhanced after combining zoledronate and sunitinib. CONCLUSION: Our findings provided support for a synergistic contribution of anti-angiogenic drugs to anti-resorptive drugs-based MRONJ. Importantly, the present study revealed that anti-angiogenic drugs alone do not induce severe MRONJ but aggravate the degree of MRONJ via the enhanced inhibitory function of gingival fibroblasts based on anti-resorptive drugs.

Reconstruction of Complete Bilateral Maxillary Defects With Free Flaps.

ABSTRACT: Reconstruction of complete bilateral maxillary defects (CBMDs) can be challenging due to the extensive loss of bone and soft tissues. This is a retrospective case series of 46 consecutive patients with CBMDs that were reconstructed with different micro-vascular free flaps. The authors aimed to evaluate the surgical outcomes and discuss the different reconstruction options in this case series. Thirty-six patients underwent reconstruction following ablation surgery for malignant tumors, 6 for benign tumors, 3 patients were treated for osteomyelitis, and 1 patient underwent free flap reconstruction for posttraumatic defects. Free fibula flap (n = 26) is the most commonly used reconstruction method in this case series, which was used in all defect types. This is followed by anterolateral thigh flap (n = 10), 5 rectus abdominis myocutaneous free flap, 3 radial forearm free flaps, and 2 composite free flaps. In this series, 44 free flaps survived, whereas only 2 flaps were lost. All patients could resume a soft diet postoperatively. Reconstruction of CBMDs with vascularized free flaps is a safe and reliable procedure.

Navigation in bone-impacted premaxillary supernumerary tooth removal: a preliminary clinical trial.

AIM: The present clinical trial aimed to preliminarily assess whether navigation could help to position impacted supernumerary teeth (STs) and reduce surgical trauma. MATERIALS AND METHODS: Subjects with an impacted supernumerary tooth (ST) in the premaxillary area were enrolled in the study and randomly distributed into a navigation group and a control group. In the navigation group, STs were positioned and extracted under real-time optic navigation. In the control group, STs were extracted depending on the surgeon's experience. Subjects were followed up for 12 to 24 weeks postsurgery. Operating time, futile bony trauma, and the positioning precision of the STs were the major outcomes assessed. Multivariate correlation analysis was performed. RESULTS: In 24 subjects, 32 STs were removed and no severe complications occurred in either group. The proportion of ST exposure at the planned access point was 100% in the navigation group and 68.75% in the control group (χ² = 5.926, P = 0.015). Futile length, futile width, and the distance between the point where the ST was initially exposed and the bony point planned for accessing it were related to both navigation/control grouping and bone thickness in the access side. For challenging STs with bone thickness of > 0.5 mm in the access side (N = 22), the futile length in the navigation group (0.0 [0.0, 4.0] mm) was significantly smaller than that in the control group (3.0 [0.0, 8.0] mm, P = 0.028). Similarly, the futile width in the navigation group (0.0 [0.0, 2.0] mm) was significantly smaller than that in the control group (2.0 [0.0, 4.0] mm, P = 0.018). CONCLUSIONS: Navigation helped to position impacted STs precisely and reduced surgical bony trauma to some extent, especially in challenging cases in which the bone in the access side was thicker than 0.5 mm.

Double-Barrel Fibula Flap Versus Vascularized Iliac Crest Flap for Mandibular Reconstruction.

PURPOSE: The double-barrel fibula flap and vascularized iliac crest flap are both commonly used for mandibular reconstruction. The present study compared the usage and reconstruction outcomes of transplanted bone with these 2 methods. PATIENTS AND METHODS: The data from 30 patients who had undergone mandibular osteotomy and reconstruction were retrospectively reviewed. Of the 30 patients, 20 received a vascularized iliac crest flap (group A) and 10 received a double-barrel fibula flap (group B). The following variables were compared between the 2 groups: volume of bone flap (VBF), volume of effective bone flap (VEBF; ie, overlap between the volume of the ideal mandible [VIM] and the VBF), usage of the bone flap (VEBF divided by the VBF), mandibular reconstruction rate (VEBF divided by the VIM), volume of needless bone flap (VNBF; ie, VBF minus VEBF; the VNBF included the volume of needless buccal bone flap [VNBBF] and the volume of needless lingual bone flap [VNLBF]), percentage of alveolar crest restoration (PACR; ie, effective bone flap width divided by ideal alveolar crest width), and height of the bone flap (HBF). The independent-samples t test and the χ2 test were used to compare the variables between the 2 groups. Statistical significance was at P ≤ .05. RESULTS: Usage of the bone flap and the length of the mandibular defect were significantly greater in group B than in group A (P = .039 and P < .001, respectively). The VBF, VNBF, and VNLBF were significantly greater in group A than in group B (P < .001 for both). The mandibular reconstruction rate, VNBBF, PACR, HBF, and tooth implantation rate were comparable between the 2 groups. CONCLUSIONS: The double-barrel fibula flap can effectively restore the height of the alveolar crest, reconstruct longer mandibular defects, and provide a better buccal and lingual appearance compared with the vascularized iliac crest flap. Although the vascularized iliac crest flap can provide sufficient bone quantity, it must be contoured to the mandible.

Regeneration of the Neocondyle After Free Fibular Flap Reconstruction of the Mandibular Condyle.

PURPOSE: Shifting of the flap position after condylar reconstruction with free fibular flaps is known to occur, but its long-term effects on postoperative esthetic outcomes have not been sufficiently reported. Therefore, in this study, we evaluated the long-term morphologic stability of the free fibular flap neocondyle. PATIENTS AND METHODS: This was a retrospective cohort study. The primary outcome variables were neocondyle regeneration and neocondyle position including the distance between the glenoid fossa and the initial neocondyle (Fo-Co), the distance between the glenoid fossa and the stable neocondyle (Fo-Co'), and shifting of the neocondyle (defined as the distance between the stable neocondyle and the initial neocondyle). The primary predictor variable was time. The other variables were age, gender, diagnosis, and number of fibular segments. Correlation analysis between the predictor variables and outcome variables was performed. RESULTS: The sample was composed of 26 patients (11 male and 15 female patients) with a mean age of 31 years. Diagnosis and number of fibular segments were significantly associated with Fo-Co and Fo-Co' (P < .05). Among the 26 patients, only 11 showed neocondyle regeneration at follow-up (group A) whereas 15 did not (group B). Neocondyle regeneration was significantly associated with patient age (P < .01). Stable Fo-Co and stable time were significantly associated with neocondyle regeneration (P < .05). The mean stable time was significantly shorter in group A (3.64 ± 1.12 months) than in group B (6.67 ± 3.85 months) (P < .05), and the mean Fo-Co' was significantly shorter in group A (13.65 ± 3.94 mm) than in group B (20.68 ± 8.87 mm) (P < .05). CONCLUSIONS: The possibility of neocondyle regeneration is higher in pediatric patients than in adults. Neocondyle regeneration could result in the movement of the neocondyle toward the glenoid fossa with a shorter stable time, which could improve neocondyle repositioning. Repositioning of the neocondyle with free fibular flaps for mandibular condyle defects is a self-adaption process for temporomandibular joint function.

Somatosensory changes in Chinese patients after coronectomy vs. total extraction of mandibular third molar: a prospective study.

OBJECTIVES: This study aimed to quantitatively compare the somatosensory function changes of inferior alveolar nerve (IAN) after mandibular third molar extraction with a surgery protocol of coronectomy, as opposed to the conventional method. MATERIALS AND METHODS: Patients with a lower third molar directly contacting IAN were recruited and assigned either to a test group (coronectomy group) or a control group (conventional extraction). A standardized quantitative sensory testing (QST) battery was performed for four times: one week before surgery and the second, seventh, and 28th days after surgery. Z-scores and the loss/gain coding system were applied for each participant. RESULTS: A total of 140 molars (test group: n = 91, control group: n = 49) were enrolled. The sensitivity of the mechanical detection threshold (MDT) and pressure pain threshold (PPT) significantly increased after surgery more than before surgery in both groups (P ≤ 0.001). After the surgery, the sensitivities of the cold detection threshold (CDT), cold pain threshold (CPT), and heat pain threshold (HPT) were significantly higher in the test group than in the control group (P ≤ 0.027). The risk of IANI was significantly larger (P = 0.041) in the test group than in the control group. CONCLUSIONS: QST was a sensitive way to detect somatosensory abnormalities even with no subjective complaint caused by surgery. Coronectomy had less influence on IAN function than conventional total extraction. CLINICAL RELEVANCE: The somatosensory function changes after mandibular third molar extraction were quantitatively studied, and coronectomy was proved a reliable alternation to reduce IAN injury rate.

Selection of Guiding Plate Combined With Surgical Navigation for Microsurgical Mandibular Reconstruction.

PURPOSE: The present study summarized selection of guiding plate combined with surgical navigation for microsurgical mandibular reconstruction. METHODS: Data from preoperative maxillofacial enhanced computed tomography (CT) scans were imported to ProPlan CMF. The authors performed virtual mandibulectomy and superimposed 3-dimensional (3D) iliac images on mandibular defects. Guiding plates including mandibular fixation device, reconstruction plate, guiding model, and occlusal splint for various mandibular hemimandibular central lateral (HCL) defects were fabricated to fix bilateral residual mandible. The model was scanned, and data were imported into ProPlan CMF and the intraoperative navigation system. Through landmark points upon the guiding plate, position of the residual mandible was determined during surgical navigation. Intraoperative navigation was used to implement the virtual plan. Sagittal, coronal, axial, and 3D reconstruction images displayed by the navigation system were used to accurately determine osteotomy sites and osteotomy trajectory during surgery. Surgical probe guidance was used to mark the osteotomy line and transfer the virtual procedure to real-time surgery. Accuracy was evaluated using chromatographic analysis. RESULTS: Different guiding plates combined with surgical navigation could be used for various mandibular defects, including mandibular fixation devices for LCL defects, reconstruction plates for LC/L/C defects, and guiding models and occlusal splints for H/L/LC defects (including mandibular ramus). In our study, average and largest shift of the mandible and osteotomy site was <5 mm. CONCLUSION: The authors summarized different ways of combining guiding plates with surgical navigation for reconstruction of various mandibular defects, which could improve clinical outcomes of this procedure with high accuracy.

Development and validation of nomogram for prediction of malignant transformation in oral leukoplakia: A large-scale cohort study.

PURPOSE: Oral leukoplakia (OL) is the well-known disorder of oral mucosa, which has potential to be malignant and can lead to squamous cell carcinoma (OSCC). In the following study, we developed a comprehensive nomogram for predicting the malignant progression of OL, based on analysis of clinicopathological variables. METHODS: A retrospective analysis of patients diagnosed with OL was performed between 1998 and 2017 at the Peking University School and Hospital of Stomatology. OL was confirmed by pre-treatment biopsy. The candidate risk factors for OL malignant transformation were screened from clinicopathological variables using the Cox proportional hazard regression analysis. The nomogram model was generated based on the COX regression results and was validated through Harrell concordance index (c-index) and calibration plots RESULTS: The incidence of OL malignant transformation (MT) was 12.2% (107/875), and the mean follow-up time was 4.5 years. The risk factors (age, histologic grade, site of lesion and smoking habit) derived from Cox proportional hazard regression analysis were incorporated in a novel nomogram model for prediction of MT severity. The c-index value of the nomogram model was 0.752, which confirmed the prediction ability; and was further confirmed by calibration plots results. CONCLUSION: Our data suggest that patients with OL who are over 50 years old, non-smokers with dysplasia, and OL lesions involving the lip, the floor of mouth, and tongue have an enhanced risk of MT. The established nomogram model has the predictive value of malignant progression, which is conductive to screen high-risk patients and guide treatment strategy.

Outcomes of Zygomatic Complex Reconstruction With Patient-Specific Titanium Mesh Using Computer-Assisted Techniques.

PURPOSE: Zygomatic complex defects after extensive maxillectomy can cause severe esthetic and functional deformities. Patient-specific titanium mesh fabricated using a computer-assisted technique is a promising method for such midface reconstruction. The aim of this study was to evaluate the application and clinical outcomes of this technique. PATIENTS AND METHODS: This was a retrospective study that included 9 patients with zygomatic complex defects after extensive maxillectomy from 2015 through 2017 at the authors' institution. A 3-dimensional stereo model was obtained based on mirror images of the unaffected side to fabricate a patient-specific titanium mesh using computer-assisted design and manufacturing. Titanium mesh was used to restore the contour of the zygomatic complex with free flap reconstruction after tumor resection. Anterolateral thigh flaps were used in 8 cases and a myocutaneous fibula flap was used in 1 case. Symmetry of the zygomatic complex was evaluated by measuring the zygomatic eminence on the postoperative computed tomogram, and complications were recorded during follow-up visits. Facial symmetry was self-evaluated and scored. RESULTS: Mean duration for follow-up was 27.3 months (range, 15 to 39 months). Mean deviation of the zygomatic eminence between the reconstructed and unaffected sides was 1.4 ± 0.5 mm. No significant difference was noted in the zygomatic eminence between the reconstructed and unaffected sides (P = .591). Titanium mesh exposure occurred in only 1 patient after radiotherapy. There were no other remarkable complications. All patients were satisfied with their postoperative facial symmetry. CONCLUSION: Patient-specific titanium mesh fabricated using a computer-assisted technique was an alternative option for extensive zygomatic complex reconstruction, resulting in acceptable clinical outcomes. A study with a larger sample and long-term follow-up is needed for the observation of long-term outcomes and risk of titanium mesh-related complications.

Three-Dimensional Image Fusion of 18F-Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography and Contrast-Enhanced Computed Tomography for Computer-Assisted Planning of Maxillectomy of Recurrent Maxillary Squamous Cell Carcinoma and Defect Reconstruction.

PURPOSE: The purpose of this study was to describe new technology assisted by 3-dimensional (3D) image fusion of 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) and contrast-enhanced CT (CECT) for computer planning of a maxillectomy of recurrent maxillary squamous cell carcinoma and defect reconstruction. MATERIALS AND METHODS: Treatment of recurrent maxillary squamous cell carcinoma usually includes tumor resection and free flap reconstruction. FDG-PET/CT provided images of regions of abnormal glucose uptake and thus showed metabolic tumor volume to guide tumor resection. CECT data were used to create 3D reconstructed images of vessels to show the vascular diameters and locations, so that the most suitable vein and artery could be selected during anastomosis of the free flap. The data from preoperative maxillofacial CECT scans and FDG-PET/CT imaging were imported into the navigation system (iPlan 3.0; Brainlab, Feldkirchen, Germany). Three-dimensional image fusion between FDG-PET/CT and CECT was accomplished using Brainlab software according to the position of the 2 skulls simulated in the CECT image and PET/CT image, respectively. After verification of the image fusion accuracy, the 3D reconstruction images of the metabolic tumor, vessels, and other critical structures could be visualized within the same coordinate system. These sagittal, coronal, axial, and 3D reconstruction images were used to determine the virtual osteotomy sites and reconstruction plan, which was provided to the surgeon and used for surgical navigation. RESULTS: The average shift of the 3D image fusion between FDG-PET/CT and CECT was less than 1 mm. This technique, by clearly showing the metabolic tumor volume and the most suitable vessels for anastomosis, facilitated resection and reconstruction of recurrent maxillary squamous cell carcinoma. CONCLUSIONS: We used 3D image fusion of FDG-PET/CT and CECT to successfully accomplish resection and reconstruction of recurrent maxillary squamous cell carcinoma. This method has the potential to improve the clinical outcomes of these challenging procedures.

A Revised Approach for Mandibular Reconstruction With the Vascularized Iliac Crest Flap Using Virtual Surgical Planning and Surgical Navigation.

PURPOSE: The purpose of this study was to describe a revised approach for mandibular reconstruction with vascularized iliac crest flap using virtual surgical planning and surgical navigation. PATIENTS AND METHODS: Preoperative maxillofacial and iliac non-contrast-enhanced computed tomography (CT) scans were acquired, and CT data were imported into ProPlan CMF software (Materialise, Leuven, Belgium). We performed virtual mandibulectomy and superimposed the 3-dimensional iliac image on the mandibular defect. The surgeon shaped the iliac flap according to virtual parameters and the stereomodel. Surgical navigation was used to check and correct the shaped segments. The position of the osteotomy lines and relevant parameters regarding the shape of the iliac flap also were provided to the surgeon. After computer simulation, a reconstructed mandibular stereomodel was manufactured. A reconstruction plate was prebent and fixed on this model using titanium screws. The model was scanned, data were imported into ProPlan CMF, the mandible was segmented, and data were imported into the intraoperative navigation system. Then, the model was registered with the original CT data, and the reconstruction plate was eliminated. Navigation data were exported into a universal serial bus drive, which was connected to the terminal working station during surgery. Intraoperative navigation was used to implement the virtual plan for patients. The sagittal, coronal, axial, and 3-dimensional reconstruction images displayed by the navigation system were used to accurately determine the osteotomy sites and osteotomy trajectory during surgery. Surgical probe guidance was used to mark the osteotomy line and transfer the virtual procedure to real-time surgery. RESULTS: Using our method, we precisely recovered the original configuration of the mandible. The shift in the reconstructed mandible and plate was less than 5 mm. CONCLUSIONS: We provided a new method for mandibular reconstruction with vascularized iliac crest flap and an individual reconstruction plate using computer-assisted techniques involving surgical navigation, which have the potential to improve the clinical outcomes of this procedure.

Three-Dimensional Accuracy of Virtual Planning and Surgical Navigation for Mandibular Reconstruction With Free Fibula Flap.

PURPOSE: Although free fibula flaps are widely used for mandibular reconstruction, their 3-dimensional position is difficult to control during conventional surgery. We aimed to improve this process by using computer-aided design (CAD) and surgical navigation. PATIENTS AND METHODS: We retrospectively reviewed 29 benign tumor patients who underwent primary unilateral mandibular reconstruction with free fibula flap. They were divided into 3 groups: group A, comprising 10 patients, underwent reconstruction based on the surgeon's experience; group B, comprising 7 patients, underwent reconstruction based on CAD; and group C, comprising 12 patients, underwent reconstruction based on CAD and surgical navigation. Condyle and gonion positions and mandibular angles were measured. Operative times were recorded. RESULTS: Among the 17 patients who underwent condylar resection, the average condyle shift was greater in group A than in groups B and C (P < .05). The average gonion shift was greater in groups A and B than in group C (P < .05). The difference between the reconstructed and contralateral mandibular angles was greater in group A than in groups B and C (P < .05). The mean operative time did not differ among the 3 groups. CONCLUSIONS: CAD can guide mandibular angle remodeling and condyle placement. CAD and surgical navigation increase reconstruction accuracy without prolonging operative time.

Carcinoma Ex Pleomorphic Adenoma: Is It a High-Grade Malignancy?

PURPOSE: The objective of this study was to investigate the clinicopathologic features of carcinoma ex pleomorphic adenoma (CXPA) and comprehensively improve an understanding of this disease. MATERIALS AND METHODS: This retrospective study investigated 151 cases of histologically confirmed CXPA. Disease-specific survival, local recurrence, and regional and distant metastases were analyzed. RESULTS: Most cases were classed as frankly invasive CXPA (135 of 151). More than half these cases (73 of 135; 54.1%) developed local recurrence; 25 (18.5%) developed cervical metastasis; 21 (15.6%) developed distant metastasis; and 60 patients (55.6%) died during follow-up. In contrast, only 1 patient in the noninvasive CXPA group (n = 10) died after treatment for lung metastasis and 1 patient developed cervical metastasis. Similarly, only 1 patient in the minimally invasive CXPA group (n = 6) died of lung metastasis and the remaining 5 patients had an uneventful recovery after treatment. CONCLUSIONS: Frankly invasive CXPA was a high-grade malignancy with an unfavorable prognosis. Elective neck dissection should be performed in cases of frankly invasive CXPA that originate in the submandibular gland. Patients with minimally invasive and noninvasive CXPA should be followed closely after primary treatment because regional or distant metastasis can occur.

A New Procedure Assisted by Digital Techniques for Secondary Mandibular Reconstruction With Free Fibula Flap.

PURPOSE: To describe a new procedure assisted by digital techniques for secondary mandibular reconstruction with free fibula flap. METHODS: The 3-dimensional (3D) reconstruction images for vessels were used to demonstrate the vascular diameter and location, which help select the most suitable vein and artery for anastomosis. Maxillary and mandibular stone models of the patient were fabricated and a stable occlusal relationship was determined on an articulator. The 3D tooth model data were scanned using a 3D-optical measuring system, and the obtained stereolithographic (STL) data were imported to Geomagic software. Preoperative maxillofacial and fibular noncontrast-enhanced computed tomography scans were acquired, and the data were imported to ProPlan CMF software. The maxilla and mandible were segmented, and STL data were imported to Geomagic software. The registration function was used to determine the ideal mandibular position. First, with the maxillary position fixed, the maxillary and mandibular models were registered with the maxilla. Then, with the tooth model positions fixed, the mandible was registered with the models. The STL data for the mandible were imported to ProPlan CMF software. Virtual plan and surgical navigation were used to design and correct the mandibular and fibular position. RESULTS: Our technique enabled precise recovery of the original mandibular configuration in this patient. The shift in the reconstructed mandible and fibular segment was <5 mm. CONCLUSIONS: The authors described a new procedure for secondary mandibular reconstruction with a free fibular flap using digital techniques involving surgical navigation, which have the potential to improve the clinical outcomes of this procedure.

Prospects of Robot-Assisted Mandibular Reconstruction with Fibula Flap: Comparison with a Computer-Assisted Navigation System and Freehand Technique.

Background Function and aesthetics have a significant impact on the quality of life in patients undergoing mandibular reconstructive surgery, but achieving satisfactory results remain challenging. The aim of the study is to investigate the feasibility and accuracy of robot-assisted mandibular reconstruction with fibula flap in comparison to that with a computer-assisted navigation system and the freehand technique. Methods Experimental procedures (15 phantom studies and 6 animal experiments) were performed with a custom three-arm robotic system automatically, under the guidance of a computer-assisted navigation system, and by the freehand technique, respectively. The accuracy of the reconstruction was assessed by comparison between the preoperative and postoperative three-dimensional surface virtual models. Results All procedures were successfully performed. In the phantom study, the mean deviation of the fibula implant was 1.221, 1.581, and 2.313 mm, respectively, with the robotic system, the navigation system, and the freehand technique; in the animal experiment the corresponding figures were 1.7697, 1.7847, and 2.0815 mm, respectively. The mean deviation of the proximal mandibular ramus was 1.0420, 1.0532, 1.8800 mm with the robotic system, computer-assisted navigation system, and freehand technique, respectively, and the mean deviation of the distal mandibular segment was 1.1645, 2.7198, and 2.8445 mm, respectively. Conclusions The robotic system is feasible, efficient, and reliable for mandibular reconstruction. The accuracy of the fibula implant orientation with the robotic system was comparable to that with navigation system and superior to that with the freehand technique.

[Clinical features of osteonecrosis of jaws after bisphosphonates therapy for bone metastasis of breast cancer].

OBJECTIVE: To understand the clinical features of osteonecrosis of the jaw after bisphosphonates use for therapy of breast cancer patients with bone metastasis. METHODS: The cases diagnosed as bisphosphonates-related osteonecrosis of the jaws (BRONJ) were retrospectively analyzed from January 2011 to August 2015 in the Peking University School and Hospital of Stomatology, and those breast cancer patients with bone metastasis were selected. The clinical symptoms, imaging characteristics and treatment results were summarized. RESULTS: A total of 14 cases of breast cancer patients with bone metastasis were selected, with an average age of 60.21 years. The average time of suffering from breast cancer was 9.77 years, and the average time of bone metastasis and bisphosphonates drugs use was 5.67 and 3.29 years individually. There was no patient with systemic application history of hormone therapy, and no history of diabetes. There were 9 patients with tooth extractions history, and the mean time of bone necrosis symptoms was 8.58 months. There were 10 cases with bone necrosis occurring on mandible, 3 cases on maxilla, and one case with both upper and lower jaws involved. Among the 10 patients with surgical treatment, there were 3 cases cured, and 6 cases improved. However, the clinical symptoms of 2 cases with conservative treatment were significantly aggravated. CONCLUSION: The medication time between the bisphosphonates use beginning and the occurrence of BRONJ is relatively long. The history of diabetes and long-time hormone use did not exist in this group. Tooth extraction itself does not determine the severity of BRONJ. Mandible is the most common site involved by BRONJ. Surgical treatment can alleviate the clinical symptoms of BRONJ with breast cancer to some extent.