G Swennen

Universitat Internacional de Catalunya, Barcino, Catalonia, Spain

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Publications (44)34.6 Total impact

  • R Guijarro-Martínez, G R J Swennen
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    ABSTRACT: The exact boundaries of the upper airway subregions remain undefined. Consequently, anatomical limits vary greatly among different research groups and impede unbiased comparisons. The aim of this study was to provide clinical three-dimensional anatomical limits for the upper airway subregions, translate them into accurate and reliable cephalometric landmarks in cone beam computed tomography (CBCT) data, and validate the proposed measuring protocol. The upper airway of 40 normative individuals aged 23-35 years was evaluated with Dolphin Imaging(®) software. An appropriate grey-scale threshold value was pre-calculated. After adapting specific head positioning and virtual orientation protocols, the volume and minimum cross-sectional area of the nasopharynx, oropharynx, and hypopharynx, as previously defined by the authors, were calculated. Intra- and inter-observer reliability was excellent for volumes and moderate for areas. The sexual dimorphism analysis revealed a significantly greater oropharyngeal volume, hypopharyngeal volume, and minimum cross-sectional oropharyngeal area in males than in females. In conclusion, the proposed subregion definition showed technical feasibility and statistical reliability, especially for three-dimensional calculations. The reliability of two-dimensional calculations may be increased with improved head positioning during CBCT scanning and subsequent virtual head orientation. Standardization of the proposed anatomical limits has the potential to homogenize upper airway subregion analysis and permit comparisons among future studies.
    International Journal of Oral and Maxillofacial Surgery 04/2013; · 1.52 Impact Factor
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    ABSTRACT: Morphological changes of the condyles are often observed following orthognathic surgery. In addition to clinical assessment, radiographic evaluation of the condyles is required to distinguish the physiological condylar remodelling from pathological condylar resorption. The low contrast resolution and distortion of greyscale values in cone beam computed tomography (CBCT) scans have impeded an accurate three-dimensional (3D) rendering of the condyles. The current study proposes a novel semi-automated method for 3D rendering of condyles using CBCT datasets, and provides a clinical validation of this method. Ten patients were scanned using a standard CBCT scanning protocol. After defining the volume of interest, a greyscale cut-off value was selected to allow an automatic reconstruction of the condylar outline. The condylar contour was further enhanced manually by two independent observers to correct for the under- and over-contoured voxels. Volumetric measurements and surface distance maps of the condyles were computed. The mean within-observer and between-observer differences in condylar volume were 8.62mm(3) and 6.13mm(3), respectively. The mean discrepancy between intra- and inter-observer distance maps of the condylar surface was 0.22mm and 0.13mm, respectively. This novel method provides a reproducible tool for the 3D rendering of condyles, allowing longitudinal follow-up and quantitative analysis of condylar changes following orthognathic surgery.
    International Journal of Oral and Maxillofacial Surgery 03/2013; · 1.52 Impact Factor
  • J De Ceulaer, C De Clercq, G R J Swennen
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    ABSTRACT: A systematic review of the literature concerning robotic surgery in oral and maxillofacial (OMF), craniofacial and head and neck surgery was performed. The objective was to give a clear overview of the different anatomical areas of research in the field of OMF, craniofacial and head and neck surgery, in all its fields (pre-clinical and clinical). The present indications are outlined and the critical reader is invited to assess the value of this new technology by highlighting different relevant parameters. A PubMed and Cochrane library search yielded 838 papers published between 1994 and 2011. After screening the abstracts, 202 articles were considered clinically or technically relevant and were included. These full papers were screened in detail and classified as articles on synopsis (n=41), educational aspects (n=3), technical/practical aspects (n=11) and clinical papers (n=147). Regarding clinical feasibility this systematic review revealed the following main indications: transoral robotic surgery (TORS) for upper digestive and respiratory tract lesions; TORS for skull base surgery; and TORS for trans-axillary thyroid and endocrine surgery. Regarding functional outcome, this systematic review revealed a promising reduction of morbidity in patients with cancer of the upper digastric and respiratory tract.
    International Journal of Oral and Maxillofacial Surgery 08/2012; 41(11):1311-24. · 1.52 Impact Factor
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    ABSTRACT: The use of autologous calvarian split thickness bone grafts is a well accepted preprosthetic surgical procedure for reconstruction of the severely atrophied maxilla. Although generally accepted as being a superior bone graft regarding long-term stability, the reported risks in the literature may dissuade the surgeon. A modified cone-beam computed tomography (CBCT) scanning protocol (extended field of view starting from 1cm below the occlusal plane up to the limit of the cranial vault, 0.4 voxel) is proposed that allows assessment of both the cranial donor site as the maxillary receptor site and the sinus conditions with a single scan. Issues regarding quality of the data, radiation dose and clinical practicability are discussed.
    International Journal of Oral and Maxillofacial Surgery 04/2012; 41(7):863-6. · 1.52 Impact Factor
  • R Guijarro-Martínez, G R J Swennen
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    ABSTRACT: A systematic review of the literature concerning upper airway imaging and analysis using cone-beam computed tomography (CBCT) was performed. A PubMed search (National Library of Medicine, NCBI; revised 9th January 2011) yielded 382 papers published between 1968 and 2010. The 382 full papers were screened in detail. 46 articles were considered clinically or technically relevant and were included in this systematic review. These were classified as articles on accuracy and reliability of CBCT imaging of the upper airway (n=4), accuracy and reliability of DICOM viewers (n=2), synopsis (n=10), technical (n=7) and clinical applications (n=27). When one paper was considered related to two or more categories, it was assigned to each relevant group. Results indicate that three-dimensional (3D) analysis of the upper airway using CBCT can be achieved in an accurate and reliable manner. Important obstacles still need to be addressed, including the impact of respiration phase, influence of tongue position and mandible morphology, longitudinal and cross-sectional 3D CBCT upper airway evaluation, and 3D CBCT definition of the anatomical boundaries of the upper airway.
    International Journal of Oral and Maxillofacial Surgery 07/2011; 40(11):1227-37. · 1.52 Impact Factor
  • International Journal of Oral and Maxillofacial Surgery - INT J ORAL MAXILLOFAC SURG. 01/2011; 40(10).
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    W De Vos, J Casselman, G R J Swennen
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    ABSTRACT: This study reviewed the literature on cone-beam computerized tomography (CBCT) imaging of the oral and maxillofacial (OMF) region. A PUBMED search (National Library of Medicine, NCBI; revised 1 December 2007) from 1998 to December 2007 was conducted. This search revealed 375 papers, which were screened in detail. 176 papers were clinically relevant and were analyzed in detail. CBCT is used in OMF surgery and orthodontics for numerous clinical applications, particularly for its low cost, easy accessibility and low radiation compared with multi-slice computerized tomography. The results of this systematic review show that there is a lack of evidence-based data on the radiation dose for CBCT imaging. Terminology and technical device properties and settings were not consistent in the literature. An attempt was made to provide a minimal set of CBCT device-related parameters for dedicated OMF scanners as a guideline for future studies.
    International Journal of Oral and Maxillofacial Surgery 07/2009; 38(6):609-25. · 1.52 Impact Factor
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    ABSTRACT: This study evaluated whether measurements on conventional frontal radiographs are comparable with measurements on cone beam computed tomography (CBCT)-constructed frontal cephalometric radiographs taken from dry human skulls. CBCT scans and conventional frontal cephalometric radiographs were made of 40 dry skulls. With I-Cat Vision((R)) software, a cephalometric radiograph was constructed from the CBCT scan. Standard cephalometric software was used to identify landmarks and calculate ratios and angles. The same operator identified 10 landmarks on both types of cephalometric radiographs on all Images 5 times with a time-interval of 1 week. Intra-observer reliability was acceptable for all measurements. The reproducibility of the measurements on the frontal radiographs obtained from the CBCT scans was higher than those on conventional frontal radiographs. There is a statistically significant and clinically relevant difference between measurements on conventional and constructed frontal radiographs. There is a clinically relevant difference between angular measurements performed on conventional frontal cephalometric radiographs, compared with measurements on frontal cephalometric radiographs constructed from CBCT scans, owing to different positioning of patients in both devices. Positioning of the patient in the CBCT device appears to be an important factor in cases where a 2D projection of the 3D scan is made.
    International Journal of Oral and Maxillofacial Surgery 05/2009; 38(7):773-8. · 1.52 Impact Factor
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    ABSTRACT: In 3D photographs the bony structures are neither available nor palpable, therefore, the bone-related landmarks, such as the soft tissue gonion, need to be redefined. The purpose of this study was to determine the reproducibility and reliability of 49 soft tissue landmarks, including newly defined 3D bone-related soft tissue landmarks with the use of 3D stereophotogrammetric images. Two observers carried out soft-tissue analysis on 3D photographs twice for 20 patients. A reference frame and 49 landmarks were identified on each 3D photograph. Paired Student's t-test was used to test the reproducibility and Pearson's correlation coefficient to determine the reliability of the landmark identification. Intra- and interobserver reproducibility of the landmarks were high. The study showed a high reliability coefficient for intraobserver (0.97 (0.90 - 0.99)) and interobserver reliability (0.94 (0.69 - 0.99)). Identification of the landmarks in the midline was more precise than identification of the paired landmarks. In conclusion, the redefinition of bone-related soft tissue 3D landmarks in combination with the 3D photograph reference system resulted in an accurate and reliable 3D photograph based soft tissue analysis. This shows that hard tissue data are not needed to perform accurate soft tissue analysis.
    International Journal of Oral and Maxillofacial Surgery 02/2009; 38(3):267-73. · 1.52 Impact Factor
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    ABSTRACT: Cone-beam computed tomography (CBCT) is used for maxillofacial imaging. 3D virtual planning of orthognathic and facial orthomorphic surgery requires detailed visualisation of the interocclusal relationship. This study aimed to introduce and evaluate the use of a double CBCT scan procedure with a modified wax bite wafer to augment the 3D virtual skull model with a detailed dental surface. The impressions of the dental arches and the wax bite wafer were scanned for ten patient separately using a high resolution standardized CBCT scanning protocol. Surface-based rigid registration using ICP (iterative closest points) was used to fit the virtual models on the wax bite wafer. Automatic rigid point-based registration of the wax bite wafer on the patient scan was performed to implement the digital virtual dental arches into the patient's skull model. Probability error histograms showed errors of < or =0.22 mm (25% percentile), < or =0.44 mm (50% percentile) and < or =1.09 mm (90% percentile) for ICP surface matching. The mean registration error for automatic point-based rigid registration was 0.18+/-0.10 mm (range 0.13-0.26 mm). The results show the potential for a double CBCT scan procedure with a modified wax bite wafer to set-up a 3D virtual augmented model of the skull with detailed dental surface.
    International Journal of Oral and Maxillofacial Surgery 01/2009; 38(1):48-57. · 1.52 Impact Factor
  • Journal of Cranio-maxillofacial Surgery - J CRANIO MAXILLOFAC SURG. 01/2008; 36.
  • Journal of Cranio-maxillofacial Surgery - J CRANIO MAXILLOFAC SURG. 01/2008; 36.
  • Journal of Cranio-maxillofacial Surgery - J CRANIO MAXILLOFAC SURG. 01/2008; 36.
  • Journal of Cranio-maxillofacial Surgery - J CRANIO MAXILLOFAC SURG. 01/2008; 36.
  • Journal of Cranio-maxillofacial Surgery - J CRANIO MAXILLOFAC SURG. 01/2008; 36.
  • Journal of Cranio-maxillofacial Surgery - J CRANIO MAXILLOFAC SURG. 01/2008; 36.
  • Journal of Cranio-maxillofacial Surgery - J CRANIO MAXILLOFAC SURG. 01/2008; 36.
  • International Journal of Oral and Maxillofacial Surgery 11/2007; 36(11):1017-1017. · 1.52 Impact Factor
  • G R J Swennen, E-L Barth, C Eulzer, F Schutyser
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    ABSTRACT: Three-dimensional (3D) virtual planning of orthognathic surgery requires detailed visualization of the interocclusal relationship. The purpose of this study was to introduce the modification of the double computed tomography (CT) scan procedure using a newly designed 3D splint in order to obtain a detailed anatomic 3D virtual augmented model of the skull. A total of 10 dry adult human cadaver skulls were used to evaluate the accuracy of the automatic rigid registration method for fusion of both CT datasets (Maxilim, version 1.3.0). The overall mean registration error was 0.1355+/-0.0323 mm (range 0.0760-0.1782 mm). Analysis of variance showed a registration method error of 0.0564 mm (P < 0.001; 95% confidence interval = 0.0491-0.0622). The combination of the newly designed 3D splint with the double CT scan procedure allowed accurate registration and the set-up of an accurate anatomic 3D virtual augmented model of the skull with detailed dental surface.
    International Journal of Oral and Maxillofacial Surgery 03/2007; 36(2):146-52. · 1.52 Impact Factor
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    ABSTRACT: The aim of this pilot study was to investigate the potential of calcium phosphate cement in the treatment of orbital wall defect fractures in an adult sheep model, and to compare this alloplastic material to autologous calvaria split-bone grafts. Clinical, volumetric and histological examinations were carried out of both reconstruction materials. The use of cement made intraoperative corrections easier to perform, and increased the precision of reconstruction of the orbital volume. This material also proved to be osseoconductive. The two materials were used successfully in combination. Regions of most intensive remodelling were the anterior orbital floor and the adjacent orbital rim. The preliminary results of this study demonstrate the potential of calcium phosphate cement as a useful biomaterial in the reconstruction of the anterior orbital region. Further animal and clinical trials are necessary to investigate its ability as a carrier for mediators where bone healing requires influence or support.
    International Journal of Oral and Maxillofacial Surgery 02/2007; 36(1):54-61. · 1.52 Impact Factor

Publication Stats

732 Citations
34.60 Total Impact Points

Institutions

  • 2013
    • Universitat Internacional de Catalunya
      Barcino, Catalonia, Spain
  • 2011
    • Hospital Clínico Universitario de Valencia
      Valenza, Valencia, Spain
  • 2000–2005
    • Hannover Medical School
      • Center of Dental, Oral and Maxillofacial Science
      Hanover, Lower Saxony, Germany
    • University Hospital Brussels
      Bruxelles, Brussels Capital Region, Belgium
  • 2002
    • Center For Oral & Maxillofacial Surgery
      Georgia, United States
  • 1999
    • Wolfson Childrens Hospital
      Jacksonville, Florida, United States