Virtual tumor mapping and margin control with 3-D planning and navigation.

Computer technology-based treatment approaches like intraoperative navigation and intensity-modulated radiation therapy have become important components of state of the art head and neck cancer treatment. Multidirectional exchange of virtual three-dimensional patient data via an interdisciplinary platform allows all medical specialists involved in the patients treatment to take full advantage of these technologies. This review article gives an overview of current technologies and future directions regarding treatment approaches that are based on a virtual, three-dimensional patient specific dataset: storage and exchange of spatial information acquired via intraoperative navigation allow for a highly precise frozen section procedure. In the postoperative setting, virtual reconstruction of the tumor resection surface provides the basis for improved radiation therapy planning and virtual reconstruction of the tumor with integration of molecular findings creates a valuable tool for postoperative treatment and follow-up. These refinements of established treatment components and novel approaches have the potential to make a major contribution to improving the outcome in head and neck cancer patients.

Analysis of the accuracy of computer-assisted DCIA flap mandibular reconstruction applying a novel approach based on geometric morphometrics.

BACKGROUND: This study evaluated the accuracy of computer-assisted surgery (CAS)-driven DCIA (deep circumflex iliac artery) flap mandibular reconstruction by traditional morphometric methods and geometric morphometric methods (GMM). METHODS: Reconstruction accuracy was evaluated by measuring distances and angles between bilateral anatomical landmarks. Additionally, the average length of displacements vectors between landmarks was computed to evaluate factors assumed to influence reconstruction accuracy. Principal component analysis (PCA) was applied to unveil main modes of dislocation. RESULTS: High reconstruction accuracy could be demonstrated for a sample consisting of 26 patients. The effect of the number of segments and length of defect on reconstruction accuracy were close to the commonly used significance threshold (p = 0.062/0.060). PCA demonstrated displacement to result mainly from sagittal and transversal shifts. CONCLUSIONS: CAS is a viable approach to achieve high accuracy in mandibular reconstruction and GMM can facilitate the evaluation of factors influencing reconstruction accuracy and unveil main modes of dislocation in this context.

Computed Tomography-Based Investigation on the Effects of Intravenous Bisphosphonate Administration on Tooth Growth in a Minipig Animal Model.

Background and Objectives: The objective of this study was to evaluate the effects of bisphosphonate (BP) administration on tooth growth, using CT-data of a minipig animal model investigation. Materials and Methods: Tooth growth was evaluated in minipigs, with eight animals receiving weekly zoledronate (ZOL) and three animals serving as the control group. Tooth growth was evaluated at the right 2nd molar (M2) in the maxilla. A computed tomography-based measuring method was applied to evaluate tooth growth in the coronal-apical, buccal-oral and mesial-distal axis. Results: ZOL-administration was found to impact tooth growth in all evaluated measuring axes, with the highest effect observed in the coronal-apical axis. Conclusions: Detrimental effects of BP administration on growing teeth have been reported by a number of investigators. The results of this investigation demonstrate that intravenous ZOL affects the growth of the whole tooth within a short period of administration. With BPs being administered to a growing number of pediatric patients, further studies should be conducted to qualify and quantify the effects of BPs on developing teeth.

Zoledronate induces bisphosphonate-related osteonecrosis of the jaw in osteopenic sheep.

OBJECTIVES: Bisphosphonate-related osteonecrosis of the jaw (BP-ONJ) occurs in 1 % of patients with medication-induced osteoporosis treated with bisphosphonates. Sheep are an established large animal model for investigating osteoporotic skeletal changes. Zoledronate significantly reduces tissue mineral variability in ovariectomized sheep. The aim of this study was to analyze bone healing after tooth extraction in sheep with induced osteopenia and zoledronate administration. MATERIALS AND METHODS: Eight adult ewes were randomly divided into two groups of four animals. All sheep underwent ovariectomy and a low-calcium diet. Dexamethasone was administered weekly for 16 weeks. Zoledronate was then given every third week for a further 16 weeks in four sheep; these infusions were repeated after extraction of two lower premolars. Four sheep without zoledronate administrations served as controls. RESULTS: Due to general health conditions, two sheep of the zoledronate group had to be excluded before surgery. The remaining two sheep of this group developed BP-ONJ lesions at the extraction site and various other sites in both jaws. Control group animals showed uneventful wound healing. Histology of the alveolar processes as well as lumbar spine revealed larger portions of old bone and smaller portions of new bone in the zoledronate group. CONCLUSIONS: This animal study showed uneventful wound healing after tooth extraction in osteopenic sheep whereas zoledronate treatment leads to development of BP-ONJ-like lesions. CLINICAL RELEVANCE: As bisphosphonate administration is a standard treatment for glucocorticoid-induced osteoporosis, this model can be used for further research in pathogenesis and management of bisphosphonate-related adverse events.

Preoperative cervical lymph node size evaluation in patients with malignant head/neck tumors: comparison between ultrasound and computer tomography.

PURPOSE: The spread of malignant lymph nodes due to malignancies of the head and neck is systematically observed. However, sentinel lymph nodes in the cervical region, such as in the axillary or supraclavicular regions, are not described. Therefore, precise preoperative lymph node screening of all neck compartments is required. MATERIALS AND METHODS: Forty-five patients with a primary malignant tumor in the head and neck area underwent lymph node staging of the head by means of both CT and ultrasound as a preoperative evaluation. The lymph nodes were classified on the origin of the level system proposed by Som et al. (174:837-844, 2000), which is based on the recommendation of the American College of Radiology introduced in 1990. According to the manual measurement of World Health Organization and the Revised Response Evaluation Criteria in Solid Tumors, the longest transversal and longitudinal diameters were measured by ultrasound, while only the two longest transversal diameters were recorded by CT. The study was conducted by two independent observers. These results were compared with the histopathological results as references. RESULTS: Six hundred and twenty-four lymph nodes were detected, 64 of which were malignant. Most of the transformed lymph nodes were found in level IIa, II b and III. A more precise measurement was given using ultrasound. The correct positive rate of sonographically detected malignant lymph nodes was significantly higher compared to the CT reading. CONCLUSION: Cervical lymph node staging can be performed safely by ultrasound. It is a cheap, easy-to-handle and cost-effective diagnostic method. However, only the uppermost regions of the neck are accessible with a linear transducer. Despite this restriction, ultrasound is a reliable and valuable tool for screening lymph nodes in the case of a head or neck malignancy.

Maxillary sinus floor augmention with autogenous bone grafts to enable placement of SLA-surfaced implants: preliminary results after 15-40 months.

This study presents preliminary results of placing SLA(R) surfaced ITI(R) implants in conjunction with maxillary sinus floor augmentations using autogenous bone. One hundred and eighty three ITI implants (SLA(R) surface) were inserted after 66 sinus floor elevation procedures in 41 consecutive patients. Forty-eight implants were placed simultaneously and 135 implants in a staged procedure with an average healing time of 4.9 months (148 days) after sinus grafting. Loading of the implants was allowed following an average time of 4.1 months (122 days). The follow-up time was 15-40 months after implant placement. Clinical follow-up consisted of single tooth and panoramic X-rays, and determination of Bleeding On Probing (BOP) and Plaque Index. One implant failed. One hundred and eleven of the inserted implants were used for fixed dentures, 20 for bar constructions, 41 for single crowns, and 11 were loaded provisionally until today. The total 2-year implant survival rate was 99.5%. Keeping the short follow-up period in mind, the encouraging results compared with previous studies, further support the findings of a positive influence of rough surfaces in grafted bone.