The prognostic relevance of lymph node ratio in patients with oral squamous cell carcinoma treated with neoadjuvant therapy regimen and radical surgery.

BACKGROUND: This study aims at investigating the prognostic significance of lymph node ratio (LNR) in a cohort of patients with oral squamous cell carcinomas (OSCC), treated with neoadjuvant radiochemotherapy followed by radical surgery. METHODS: The study included 171 treatment-naive patients with biopsy-proven primary OSCC, being reviewed retrospectively. All patients received a concomitant neoadjuvant radiochemotherapy (RCT) followed by radical surgery of the primary tumor and neck dissection based on the pretreatment staging results. The Kaplan-Meier survival analysis method was used to estimate the events of interest for overall survival (OS). Prognostic factors were identified through univariate and multivariate analysis. RESULTS: The 5-year overall survival rate for all patients was 48 %. In univariate analysis, patient's age and data compiled from the histopathological examination as margin status, extracapsular spread, ypT, ypN, ypUICC, number of positive lymph nodes and lymph node ratio (LNR) had a statistically significant impact on overall survival. Multivariate analysis revealed an independent significant impact of patient age, ypT, margin status and LNR on OS. ypN showed no statistical significant impact on OS. CONCLUSION: Our results show that LNR is an important predictor for OS in patients with OSCC that were treated with neoadjuvant radiochemotherapy and radical surgery.

Three-dimensional cone beam computed tomography analysis of maxillary sinus and alveolar bone anatomy in the restorative axis of dental implants using radiopaque drill guides.

The objectives were to assess the sinus anatomy and alveolar ridge dimensions and to identify clinical factors and morphological relationships that may predict the characteristics of the sinus anatomy. A total 336 edentulous molar and 168 edentulous premolar regions were analyzed. The mediolateral maxillary sinus (5mm and 10mm above alveolar bone), lateral maxillary sinus wall, ostium height, and alveolar ridges were measured. Measurement regions were defined by radiopaque simulation of the restoration goal. Mean molar mediolateral dimensions were >10mm: first molar, 11.8mm (range 3.8-21.1mm); second molar, 12.2mm (range 7.9-20.1mm). The extent of the sinus differed significantly between premolars and molars (P<0.001). The first molar region had the highest mean value for the lateral sinus wall (2.4mm, range 0.2-7.9mm) and the greatest distance between the alveolar crest and simulated restorative goal (8.1mm, range 1.1-16.3mm). Septum prevalence was 46% in the molar region and 27% in the premolar region. A lower alveolar ridge height was associated with a wider transverse extent of maxillary sinus and consequently longer distances between the crest and restorative goal. Systematic three-dimensional analysis of the maxillary sinus yields precise preoperative information about sinus configurations. There were significant variations and relationships among characteristics of the maxillary sinus, ridge, and the restorative goal.

Three-dimensional fracture pattern analysis of the Obwegeser and Dal Pont bilateral sagittal split osteotomy.

The Obwegeser and Dal Pont modification of the bilateral sagittal split osteotomy (BSSO) is a well-established procedure in orthognathic surgery. The purpose of this retrospective study was to analyze the actual fracture patterns achieved with BSSO by Obwegeser and Dal Pont modification using postoperative cone beam computed tomography (CBCT) datasets from 100 patients. A total of 200 split osteotomies were assessed, which could be categorized into nine different split patterns. Only one of the observed split fractures (0.5%) followed exactly the fracture line described by Obwegeser and Dal Pont, whereas 40% followed the fracture line according to the Hunsuck and Epker modification and 13.5% were seen as unfavourable splits mainly running over the buccal plate. A significant correlation was found between unfavourable buccal splits and both horizontal osteotomies reaching the buccal surface at the dorsal ramus (P=0.001) and a vertical caudal bone cut end at the corpus with a buccal position (P<0.001). These results show that a complete antero-posterior horizontal osteotomy at the mandibular ramus does not lead to the intended fracture pattern, which rebuts the argument of a greater amount of bony overlap using the Obwegeser and Dal Pont modification.

Accuracy of peri-implant bone evaluation using cone beam CT, digital intra-oral radiographs and histology.

OBJECTIVES: The present study assesses the accuracy of three-dimensional (3D) cone beam CT (CBCT) and intra-oral radiography (CR) in visualizing peri-implant bone compared with histology. METHODS: 26 titanium dental implants were placed in dog jaws with chronic type vestibular defects. After a healing period of 2 and 8 weeks (n = 12 dogs) the animals were sacrificed. CBCT scans and CR of the specimen were recorded. Dissected blocks were prepared, and histomorphometric analysis was performed. Both modalities were measured twice by two observers and compared with histomorphometry regarding bone levels and thickness around implants as well as length and diameter of implants. RESULTS: Measurements of CBCT correlated well with histomorphometry of the vestibular bone level, oral bone thickness and implant length (all p-values <0.05). Compared with histomorphometry, the mean differences between CBCT and histomorphometry were between 0.06 and 2.61 mm. Mesial bone level (MBL) and distal bone level (DBL) were underestimated by both CR and CBCT. CR and histology measurements were only significantly correlated for implant length measurements. All intraclass correlations were highly significant. CONCLUSIONS: 3D CBCT provides usable information about bone in all dimensions around implants with varying accuracy. CR and CBCT perform similar in assessing MBL and DBL, but, within its limits, the CBCT can assess oral and buccal bone. Metallic artefacts limit the visualization quality of bone around implants and further research could elucidate the value of post-processing algorithms. When information about osseous perforation of implants is needed, CBCT may still provide clinically valuable information.

Histopathological assessment of tumour regression, nodal stage and status of resection margins determines prognosis in patients with oral squamous cell carcinoma treated with neoadjuvant radiochemotherapy.

OBJECTIVES: In advanced oral squamous cell carcinoma (OSCC), tumour regression after neoadjuvant radiochemotherapy seems to be an important prognostic factor. In this study, we intended to compare regression grading according to two previously described regression models and to analyse the association of tumour regression and other tumour characteristics with patients' characteristics and overall survival. METHODS: The retrospective study included 63 treatment-naive patients with primary OSCC of stages II-IV, who were treated with a concomitant neoadjuvant radiochemotherapy followed by radical surgery. Assessment of histopathological features was performed, there under regression grading according to two previously described regression models. RESULTS: Both tumour regression models provided comparable results in terms of distribution of different regression grades. In univariate analysis regression gradings (P = 0.003 and P = 0.007), ypT-stage, ypN-stage and status of resection margins (P < 0.001) were significantly associated with the 5-year overall survival (OS). None of the pretreatment clinicopathological parameters showed association with histopathological tumour regression. Multivariate analysis revealed the status of resection margins and of lymph node metastasis as statistically significant features for OS (P = 0.020 and P = 0.003, respectively). CONCLUSION: Tumour regression grading, nodal stage and status of resection margins predict prognosis in patients after neoadjuvant treatment. Currently, there are no pretreatment clinicopathological parameters, which predicting good tumour response to therapy. Thus, identifying non-responding patients, which might benefit from an intensified systemic therapy, requires surgical resection and consecutive histopathological assessment. Therefore, further investigation and validation of new, especially, molecular predictors of tumour response to radiochemotherapy remains an unmet, future clinical need.

Possibilities and limitations of implant placement by virtual planning data and surgical guide templates.

The use of computer-aided surgical systems for dental implant bed preparation and implant placement results in an average precision within 1 mm of implant position and within 5 degrees of deviation for implant inclination. The accuracy of axis and implant position is significantly more precise with the three-dimensional surgical guide than with the free-hand method. The three-dimensional assessment of the restorative goal (radiopaque simulation of prosthesis with scanning template) allows virtual planning of implants, which enables optimized positioning of implants with surgical guide templates in oral surgery. If there is a clear indication for three-dimensional diagnostics, it should always be checked whether the data can be used as planning data for a surgical guide template, otherwise the chance for guided surgery remains unused. Since uncertainties still exist despite the use of a drilling template, it is recommended that the minimum safety distance from adjacent structures be maintained. The successful use of surgical guide templates requires comprehensive knowledge of and experience in using three-dimensional information for the virtual planning of implant position.

Podoplanin expression in oral leukoplakia: prognostic value and clinicopathological implications.

OBJECTIVES: Current clinicopathological parameters cannot predict the risk of malignant transformation in oral leukoplakia sufficiently. Recent studies have shown that podoplanin is expressed in oral cancer and precancerous lesions. The aim of our study was to assess whether podoplanin expression in pretreatment biopsies could serve as a biomarker to predict the risk of malignant transformation in patients with oral leukoplakia. MATERIALS AND METHODS: In this retrospective study, podoplanin expression was analysed in 60 patients with previously untreated oral leukoplakia by immunohistochemistry. We investigated the associations between podoplanin expression and various clinicopathological variables including oral cancer-free survival (OCFS) and the SIN-classification. RESULTS: The chi-square-test revealed that high expression of podoplanin in pretreatment biopsies was associated with malignant transformation (P = 0.003) and increasing SIN-classification (P = 0.009). In univariate analysis, podoplanin expression in oral leukoplakia had a significant impact on OCFS (P = 0.009). The 5-year OCFS rate decreased from 100% for patients with no podoplanin expression to 41.7% for patients with the highest level of podoplanin expression. CONCLUSION: Although podoplanin expression and the SIN-classification served as factors to predict malignant transformation in patients with oral leukoplakia in univariate analysis, no significant impact was found for both factors in multivariate analysis.

Registration accuracy of three-dimensional surface and cone beam computed tomography data for virtual implant planning.

OBJECTIVE: Virtual wax-ups based on three-dimensional (3D) surface models can be matched (i.e. registered) to cone beam computed tomography (CBCT) data of the same patient for dental implant planning. Thereby, implant planning software can visualize anatomical and prosthetic information simultaneously. The aim of this study is to assess the accuracy of a newly developed registration process. MATERIAL AND METHODS: Data pairs of CBCT and 3D surface data of 16 patients for dental implant planning were registered and the discrepancy between the visualized 3D surface data and the corresponding CBCT data were measured on 64 teeth at seven points by two investigators in two iterations with a total of 1792 measurements. RESULTS: All data pairs were matched successfully and mean distances between CBCT and 3D surface data were between 0.03(±0.33) and 0.14(±0.18) mm. At two of seven measuring points, statistically significant correlations were determined between the measured error and the presence and type of restorations. Registration errors in maxilla and mandible were not statistically significantly different. CONCLUSION: According to the results of this study, registration of 3D surface data and CBCT data works reliably and is sufficiently accurate for dental implant planning. Thereby, barium-sulfate scanning templates can be avoided and dental implant planning can be accomplished fully virtual.

CAD/CAM-produced surgical guides: Optimizing the treatment workflow.

The increased availability of devices for 3D radiological diagnosis allows the more frequent use of CAD/CAM-produced surgical guides for implant placement. The conventional workflow requires a complex logistic chain which is time-consuming and costly. In a pilot study, the workflow of directly milled surgical guides was evaluated. These surgical guides were designed based on the fusion of an optical impression and the radiological data. The clinical use showed that the surgical guides could be accurately placed on the residual dentition without tipping movements. The conventional surgical guides were used as a control for the manual check of the deviation of the implant axis. The direct transfer of the digital planning data allows the fabrication of surgical guides in an external center without the need of physical transport, which reduces the logistic effort and expense of the central fabrication of surgical guides.

Intraoral molluscum contagiosum imitating a squamous-cell carcinoma in an immunocompetent person--case report and review of the literature.

A case of intraoral molluscum contagiosum involving the right distal alveolar bridge of an immunocompetent person is reported. A review of the literature, with only five previously published cases, revealed that involvement of the oral soft tissues is rare.

Biomechanical comparison of four different miniscrew types for skeletal anchorage in the mandibulo-maxillary area.

This study compared four miniscrew types for skeletal anchorage (Aarhus, FAMI, Dual Top and Spider) regarding their biomechanical properties contributing to primary stability. Insertion torque measurements and pull-out tests in axial (0 degrees ) as well as in the 20 degrees and 40 degrees direction were performed. Stiffness of the screw-bone construct was calculated from the load-displacement curve. Conic FAMI and Dual Top screws had higher insertion torques. Insertion torques were raised by drill-free insertion of FAMI and Dual Top screws. Statistically significant differences were found between the 4 screw types in pull-out tests. The highly significant differences between the four screws for peak load in the axial (0 degrees ) and 20 degrees direction were not apparent in 40 degrees angular loads. For the conical screws, peak load values increased in angular compared with axial load. The Dual Top screw achieved the highest values for peak load and stiffness. 12 Dual Top and 1 Spider screw heads fractured in the pull-out tests. A conical drill-free screw design achieves higher primary stability compared with cylindrical self-tapping screws. This effect was more obvious in insertion torque estimations rather than in pull-out tests. The Dual Top screws, although biomechanically superior to other screw types, were most prone to fractures.

Healing of onlay mandibular bone grafts covered with collagen membrane or bovine bone substitutes: a microscopical and immunohistochemical study in the sheep.

The objective of this study was to evaluate the role of collagen membrane and Bio-Oss coverage in healing of an onlay graft to the mandible. Twelve adult sheep each received an onlay bone graft (experiment 1), bone graft+Bio-Gide (experiment 2), and bone graft+Bio-Oss/Bio-Gide (experiment 3) on the lateral surface of the mandible. The animals were euthanized at 4, 8, 12 or 16 weeks after surgery, and findings were analysed by routine microscopy and immunohistochemistry for proliferation (Ki67) and apoptotic (Caspase-3) markers. Grafts were fully incorporated in all specimens. Pronounced resorption was observed in experiment 1. Minimal loss of graft volume was seen in experiment 2 specimens without membrane displacement. A remarkable increase in the augmented region of the mandible was observed in experiment 3. A high number of osteoclasts were expressed within the grafts during the early healing period, and thereafter declined markedly. Osteoblasts within the grafts expressed a moderate level of Ki67 at 8 weeks, which thereafter declined markedly. The strongest expression of Caspase-3 on the bone surface was observed after 16 weeks. In conclusion, the effect of collagen membrane coverage on bone graft volume maintenance was dependent on membrane stability during healing. An autogenous bone graft covered with Bio-Oss particles resulted in a remarkable increase in augmented lateral surface of the mandible. The late stage of bone graft healing was associated with a high apoptotic induction pathway of osteoblasts lining the surfaces of the new bone, demonstrated by strong positive Caspase-3 immunoreactivity.

Diagnostic quality of multiplanar reformations obtained with a newly developed cone beam device for maxillofacial imaging.

OBJECTIVES: To compare the diagnostic quality of multiplanar reformations generated by a newly developed cone beam device with the diagnostic quality of multiplanar reformations obtained using a state of the art multidetector row CT scanner. METHODS: Digital volume tomograms (DVTs) were obtained with the prototype of GALILEOS (Sirona Dental Systems Inc., Bensheim, Germany), a newly developed compact-sized cone beam machine with a scan volume of 15 x 15 x 15 cm. CT scans were performed for comparison with two 16-detector row CT scanners. The study included 30 image pairs obtained from the same patients. The multiplanar reformations in axial, coronal and sagittal planes were subjectively assessed by 3 observers using a 1(excellent)-5(poor) scale on 35 weighted criteria including findings detection, image quality and visualization of several anatomical structures. RESULTS: There was no statistically significant difference between DVT and CT in cumulative values expressing the diagnostic quality of the reformations (P = 0.071). The interobserver agreement was better with CT than with DVT. Findings detection and the visualization of the majority of anatomical structures within the mandibulomaxillary area were ranked at the same level for DVT as with CT. CONCLUSIONS: The diagnostic quality of multiplanar reformations can be considered the same in both devices. Although sharpness, noise level and contrast resolution do not reach the level of CT, DVT images proved statistically not inferior for the detection of lesions which may be adequately depicted by both imaging modes.

Application of a computer navigation system for the placement of orthodontic anchorage screws.

The computer navigation system Robodent, which was developed for dental implants, was used for the placement of orthodontic anchorage screws in a phantom head. The deviation between the planned and finally achieved position of the screws did not exceed that reported for dental implants. In conclusion, the system seem to be suitable and precise enough for orthodontic screws.

Intraoperative navigation in the maxillofacial area based on 3D imaging obtained by a cone-beam device.

The aim of this study was to evaluate intraoperative navigation in the maxillofacial area based on three-dimensional imaging obtained by a cone-beam device. Digital volume tomograms (DVT) were obtained by the prototype of GALILEOS (Sirona Dental Systems Inc., Bensheim, Germany), a newly developed, compact size, cone-beam machine with a scan volume of 15 cm x 15 cm x 15 cm. Intraoperative navigation was performed in 12 patients in three selected indications. Target detection error expressing the accuracy of DVT navigation and registration performance of specially developed methods for image-to-patient registration was estimated. Target detection error was maximally 2 mm and depended on the registration method chosen. The automatic detection rate of the fiducial markers ranged between 0.64 and 0.32. The preoperatively defined treatment plan was fully accomplished in 11 out of 12 cases. A favourable surgical outcome was achievable in all cases. Intraoperative complications were not observed. Intraoperative navigation based on DVT imaging can be considered as a valuable alternative to CT-based procedures. Special characteristics of the cone-beam technique, in terms of contrast resolution and the limited field-of-view size of the devices, restrict the indication spectrum and create a demand for modifications of the usual registration methods.

[A vascular pedicled duplicated fibula transplant for treatment of lumbar instability following tuberculous spondylodiscitis]. / Ein gefässgestieltes gedoppeltes Fibulatransplantat zur Behandlung der lumbalen Instabilität nach tuberkulöser Spondylodiszitis.

Operative treatment of tuberculous spondylodiscitis is still an important part of the treatment for lumbar spine instability. We report on a patient who suffered an extensive relapse with microbiological confirmation of tuberculous spondylodiscitis following operative spinal treatment for unspecific spondylodiscitis. X-Ray examination showed development of pronounced lumbar instability, which was first treated with the aid of an external fixateur and later by means of a doubled fibular bone graft with a vascularised stem with no dorsal instrumentation, which led to bony consolidation.

Comparison of static and dynamic computer-assisted guidance methods in implantology.

The planning of dental implant position and its transfer to the operation site can be considered as one of the most important factors for the long-term success of implant-supported prosthetic and epithetic restorations. This study compares computer-assisted fabricated surgical templates as the static method with intro-operative image guided navigation as the dynamic method for transfer of three-dimensional pre-operative planning. For the static method, the systems Med3D, coDiagnostix/ gonyX, and SimPlant were used. For the dynamic method, the systems RoboDent und VectorVision2 were applied. A total of 746 implants were inserted between August 1999 and December 2005 in 206 patients. The static approach was used most frequently, accounting for 611 fixtures in 168 patients. The failure ratios within the first 6 months were 1.31% in the statically controlled insertion group compared to 2.96% in the dynamically controlled insertion group. Complications related to an incorrect position of the implants have not been observed so far in either group. All computer-assisted methods included in this study were successfully applied in a clinical setting after a certain start-up period. The indications for application of computer-assisted methods in implantology are currently given in difficult anatomical situations. Due to uncomplicated handling and low resource demands, the static template technique can be recommended as the method of choice for the majority of all cases falling into this category.

Lateral femoral cutaneous nerve and iliac crest bone grafts--anatomical and clinical considerations.

This study investigates the topographical relationship of the lateral femoral cutaneous nerve (LFCN) to the anterior iliac crest and its clinical relevance in the context of bone graft harvesting. In the anatomical part of the study, LFCN was dissected and its course investigated in 34 human formalin-embalmed cadavers. In the clinical part, data of patients who underwent an iliac crest bone grafting procedure were collected and analysed. The obtained results were then compared with the results of other investigators published in the medical literature. From 34 nerves, the lateral branch of 1 LFCN (2.9%) crossed the anterosuperior iliac spine (ASIS) prominence at a distance less than 5mm superolaterally from the most anterior point of the spine. All other nerves ran below the inguinal ligament with an average distance of 14.6mm in the inferomedial direction from the spine. In 4 out of 298 patients (1.3%) who underwent harvesting of monocortical bone grafts from the inner table of the ilium, sensory disturbances in the dermatome of LFCN were observed. After a maximum period of 12 months all sensory disturbances resolved so that no case of permanent sensory impairment was recorded. The relatively low incidences of iatrogenic LFCN damage can be attributed to a standardized surgical concept which employs a lateral incision and layer by layer dissection to the periosteum/iliacal fascia level in order to identify the nerves potentially crossing the iliac crest above the ASIS.