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Objectives: A systematic review was performed to analyze the current evidence on three-dimensional (3D) computed tomography (CT) superimposition protocols used to assess dentomaxillofacial changes after orthognathic and orthofacial surgery. Accuracy, reproducibility, and efficiency were evaluated., Methods: The search was divided into Main Search (PubMed, EMBASE, Cochrane Library, LILACS, and SciELO), Grey Literature search (Google Scholar and Open Grey), and Manual search. Thirteen studies were included. Of these, 10 reported data on accuracy, 10 on reproducibility and five on efficiency. Seven proposed or evaluated methods of voxel-based superimposition, three focused on the surface-based technique, one compared surface- and voxel-based superimposition protocols, one used the maximum mutual information algorithm, and one described a landmark-based superimposition method. Cone-beam computed tomography (CBCT) was the most common imaging technique, being used in 10 studies., Results: The accuracy of most methods was high, showing mean differences smaller than voxels' dimensions, ranging between 0.05 and 1.76 mm for translational accuracy, and 0.10-1.09° for rotational accuracy. The overall reproducibility was considered good as demonstrated by the small mean error (range: 0.01-0.26 mm) and high correlation coefficients (range: 0.53-1.00). Timing to complete virtual superimposition techniques ranged between a few seconds up to 40 min., Conclusions: Voxel-based superimposition protocols presented the highest accuracy and reproducibility. Moreover, superimposition protocols that used automated processes and involved only one software were the most efficient. more...

Purpose: Transoral placement of bicortical screws is a rigid fixation method in orthognathic surgery that is used less often than transbuccal placement. The aim of this study was to examine the postoperative outcome of transoral bicortical screw insertion during orthognathic surgery and to compare it with the more common transbuccal fixation technique., Materials and Methods: A retrospective cohort study was conducted. Clinical files of orthognathic surgery patients operated on from January 2010 through December 2012 were reviewed. Screw insertion approach (transoral vs transbuccal) was examined as a predictive variable for postoperative complications (hardware removal and infection). Type of surgery, fibrin sealant, preoperative third molar removal, and patient age and gender were analyzed as potential risk factors. Descriptive and bivariate statistics and regression analyses were performed., Results: Of the 606 patients whose cases were reviewed, 509 patients (185 men; mean age, 26.3 ± 11.1 yr) met the inclusion criteria. Most presented with a Class II malocclusion (84.5%). A transbuccal approach was used in 27.5% of cases, leading to a screw-related infection of 6.3%. Patients treated with a transoral technique (72.5%) had fewer infections (3.5%), but this was not statistically relevant. Screw removal was indicated in 3.3% of patients. Screw placement using the transoral and transbuccal approaches was performed in 3.0 and 4.2% of patients, respectively. Infection and screw removal rates did not differ significantly between fixation techniques (P = .16 and P = .49, respectively)., Conclusion: The present findings showed an overall low rate of screw removal and infection secondary to bicortical screw insertion during orthognathic surgery. The postoperative outcome was similar for the transoral and transbuccal approaches., (Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.) more...

Purpose: The purpose of the present study was to introduce and evaluate the use of a modified "wax-bite dental splint" for surgical navigation in craniomaxillofacial surgery., Materials and Methods: A 2-layer wax bite dental splint was fabricated with an anterior extension, and 8 gutta percha markers were incorporated in each splint for marker-based pair-point registration. To evaluate the accuracy, the occlusal registration of the wax bite dental splint was performed on 10 artificial skulls. Consecutively, all the skulls were scanned using a standardized cone-beam computed tomography scanning protocol with the 2-layer wax bite dental splint in place. Automatic rigid marker-based pair-point registration was performed using the iPlan CMF software, version 3.0 (Brainlab AG, Feldkirchen, Germany) using 8 gutta percha markers incorporated into the wax bite dental splint. Additionally, the registration accuracy of 6 anatomic skeletal landmarks was measured on each skull., Results: The mean registration error for each wax bite dental splint ranged from 0.78 to 1.01 mm. The overall mean registration error for the wax-bite dental splint-based registration was 0.89 ± 0.08 mm. The mean registration error for the 6 anatomic landmarks ranged from 1.23 to 2.3 mm. The overall mean registration error was 1.68 ± 0.28 mm., Conclusion: The results of the present study show the potential for a wax-bite dental splint as an alternative rigid registration method for surgical navigation in craniomaxillofacial surgery. Moreover, from a clinical viewpoint, the method is accurate, user-friendly, inexpensive, and not time-consuming., (Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.) more...

A systematic review on complications in all forms of mandibular distraction osteogenesis (MDO) for acquired deformities was performed. Search terms expressing distraction osteogenesis were used in 'AND' combination with search terms comprising 'mandible' and terms for complication, failure, and morbidity. A search using PubMed (National Library of Medicine, NCBI), EMBASE, and the Cochrane Controlled Trials Register yielded 644 articles published between 1966 and mid October 2013. Three hundred and twenty-one eligible articles were screened in detail. Complications related to MDO in acquired deformities were reported in 105 clinical articles, involving 1332 patients. Treatments included alveolar distraction osteogenesis (ADO), mandibular lengthening, DO in bone grafts, and bi-/trifocal transport disc DO (TDDO) for segmental mandibular defects. A high incidence of complications was seen in MDO for acquired deformities (ADO 44.4%; residual group 43.9%). An index for classifying complications in MDO, based on the impact and further treatment or final results, was used. In the ADO group, soft tissue complications (8.0%), insufficient vector control (7.6%), temporary inferior alveolar nerve (IAN) neurosensory disturbances (6.5%), device-related problems (3.5%), mandible fractures (2.8%), insufficient bone formation (2.5%), and fracture of the transport disc (1.3%) were seen. In the residual group, temporary IAN neurosensory disturbances (13.4%), minor infection (5.3%), DO failure (4.0%), and device-related problems (3.8%) were reported., (Copyright © 2015. Published by Elsevier Ltd.) more...

A systematic review of English and non-English language articles on the complications of mandibular distraction osteogenesis (MDO) for patients with congenital deformities was performed, in accordance with the PRISMA statement. Search terms expressing distraction osteogenesis were used in 'AND' combination with search terms comprising 'mandible' and terms for complication, failure, and morbidity. A search using PubMed (National Library of Medicine, NCBI), EMBASE, and the Cochrane Central Register of Controlled Trials yielded 644 articles published between 1966 and mid October 2013. Clinical articles that reported complications related to MDO were included. Finally 81 articles on MDO in congenital deformities were eligible and were screened in detail. Complications including minor infection (6.0%), device-related problems (7.3%), skeletal open bite (2.4%), hypertrophic scar formation (2.1%), facial nerve palsy (1.8%), neurosensory disturbances of the inferior alveolar nerve (1.9%), and (fibrous) non-union (0.7%) were seen. A new index for more detailed classification of complications in MDO is proposed based on six categories that indicate the impact of the complication and its further treatment or final results. The proposed complication index may be a useful tool to classify complications related to MDO., (Copyright © 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.) more...

A systematic review of English and non-English articles on the complications of mandibular distraction osteogenesis (MDO) for patients with developmental deformities was performed, in accordance with the PRISMA statement. Search terms expressing distraction osteogenesis were used in 'AND' combination with search terms comprising 'mandible' and terms for complication, failure, and morbidity. A search using PubMed (National Library of Medicine, NCBI), EMBASE, and Cochrane Controlled Trials Register yielded 644 articles published between 1966 and mid October 2013. Clinical articles that reported complications related to MDO in developmental deformities were included. Two hundred and fifty articles were eligible and were screened in detail. A total of 32 articles reporting the cases of 565 patients were finally included. Patients underwent mandibular lengthening and transverse widening. A total of 211 complications were reported (37.4%); these were classified according to an index that indicates the clinical impact. Inferior alveolar nerve (IAN) neurosensory disturbances, minor infection, device failure, anterior open bite, permanent dental damage, and skeletal relapse were most represented. Complications that resolved spontaneously (type I) were seen in 11.0%, medically or technically manageable complications, without hospitalization, were seen in 10.8% (type II), and permanent complications (type VI) were seen in 9.6%., (Copyright © 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.) more...

The purpose of this article is to evaluate the timing for three-dimensional (3D) virtual treatment planning of orthognathic surgery in the daily clinical routine. A total of 350 consecutive patients were included in this study. All patients were scanned following the standardized "Triple CBCT Scan Protocol" in centric relation. Integrated 3D virtual planning and actual surgery were performed by the same surgeon in all patients. Although clinically acceptable, still software improvements especially toward 3D virtual occlusal definition are mandatory to make 3D virtual planning of orthognathic surgery less time-consuming and more user-friendly to the clinician., (Copyright © 2014 Elsevier Inc. All rights reserved.) more...

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., (Copyright © 2013 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.) more...

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., (Copyright © 2012 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.) more...

Objective: To evaluate the success rate of Bollard miniplate anchorage for bone anchored maxillary protraction (BAMP)., Materials and Methods: Twenty-five consecutive patients (mean age, 12.0 ± 1.2 years; range, 8.7-14.8 years) with maxillary hypoplasia without congenital or acquired deformation were included in this study. A total of 100 Bollard modified miniplates were placed by the same surgeon. Ninety-nine miniplates were inserted under general anesthesia, and one was placed under local anesthesia because of initially soft bone conditions. Loading of the miniplates with 150 g elastics was initiated at 17.5 ± 6.9 days (range, 11-38 days) after surgery. Mean follow-up was provided at 20.8 ± 11.1 months (range, 6.5-46.2 months)., Results: The overall success rate of miniplate anchorage in terms of stability was 97%. During orthodontic loading, five miniplates showed signs of mobility. After interruption of loading over 2 months, two miniplates became stable again. However, a total of three miniplates needed to be removed and were successfully replaced under local anesthesia after a mean healing period of 3 months., Conclusion: Skeletal anchorage by means of Bollard modified miniplates is effective for BAMP. Success depends on proper presurgical patient counseling, minimal invasive surgery, good postsurgical instructions, and orthodontic follow-up. more...

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., (Copyright © 2011 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.) more...

Purpose: The aim of this report was to present an integrated 3-dimensional (3D) virtual approach toward cone-beam computed tomography-based treatment planning of orthognathic surgery in the clinical routine., Materials and Methods: We have described the different stages of the workflow process for routine 3D virtual treatment planning of orthognathic surgery: 1) image acquisition for 3D virtual orthognathic surgery; 2) processing of acquired image data toward a 3D virtual augmented model of the patient's head; 3) 3D virtual diagnosis of the patient; 4) 3D virtual treatment planning of orthognathic surgery; 5) 3D virtual treatment planning communication; 6) 3D splint manufacturing; 7) 3D virtual treatment planning transfer to the operating room; and 8) 3D virtual treatment outcome evaluation., Conclusions: The potential benefits and actual limits of an integrated 3D virtual approach for the treatment of the patient with a maxillofacial deformity are discussed comprehensively from our experience using 3D virtual treatment planning clinically. more...

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. more...

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. more...

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. more...

The aim of this study was to present a new approach to acquire a three-dimensional virtual skull model appropriate for orthognathic surgery planning without the use of plaster dental models and without deformation of the facial soft-tissue mask. A "triple" cone-beam computed tomography (CBCT) scan procedure with triple voxel-based rigid registration was evaluated and validated on 10 orthognathic patients. First, the patient was scanned vertically with a wax bite wafer in place (CBCT scan No1). Second, a limited dose scan of the patient with a Triple Tray AlgiNot impression in place was carried out (CBCT scan No2). Finally, a high-resolution scan of the Triple Tray AlgiNot impression was done (CBCT scan No3). Sequential and semiautomatic triple voxel-based rigid registration (RNo1-RNo3) was performed to augment the patient's skull model with accurate occlusal and intercuspidation data (Maxilim, version 2.1.1., Medicim NV, Mechelen, Belgium). All registrations were based on the Maximisation of Mutual Information registration algorithm. Because the accuracy and stability of the voxel-based registration (RNo1) between the Triple Tray AlgiNot impression scan and the limited low-dose patient scan were not known, this particular registration step needed to be validated. The accuracy of registration was measured on a synthetic skull and showed to be highly accurate. A volume overlap of 98.1% was found for registered impression scan No1. The mean distance between registered impression scan No1 and registered impression scan No2 was 0.08 +/- 0.03 mm (range, 0.04-0.11 mm). As far as the stability of registration was concerned, successful registration with a stable optimal position was obtained with a maximum variability of less than 0.1 mm. The results of this study showed that semiautomatic sequential triple voxel-based rigid registration of the triple CBCT scans augmented the 3-D virtual skull model with detailed occlusal and intercuspidation data in a highly accurate and robust way. The method is therefore appropriate and valid for 3-D virtual orthognathic surgery planning in the clinical routine. more...

Aim: To assess the three dimensional (3D) surface accuracy of a phantom's face acquired from a cone-beam computed tomography (CBCT) scan and to determine the reliability of selected cephalometric measurements performed with Maxilim software (Medicim N.V., Mechelen, Belgium)., Material and Methods: A mannequin head was imaged with a CBCT (I-CAT, Imaging Sciences International, Inc., Hatfield, USA). The data were used to produce 3D surface meshes (Maxilim and Mimics, Materialise N.V., Leuven, Belgium) which were compared with an optical surface scan of the head using Focus Inspection software (Metris N.V., Leuven, Belgium). The intra- and inter-observer reliability for the measurement of distances between facial landmarks with Maxilim 3D cephalometry were determined by calculating Pearson correlation coefficients and intraclass correlation (ICC). The Dahlberg formula was used to assess the method error (ME)., Results: (1) The maximal range of the 3D mesh deviations was 1.9 mm for Maxilim, and 1.8mm for Mimics segmentation. (2) Test-retest and inter-observer reliability were high; Pearson's correlation coefficient was 1.000 and the ICC was 0.9998. The ME of the vertical measurements was a little larger than that calculated for the width measurements. Maximum ME was 1.33 mm., Conclusions: The 3D surface accuracy of CBCT scans segmented with Maxilim and Mimics software is high. Maxilim also shows satisfactory intra- and inter-assessor reliability for measurement of distances on a rigid facial surface. more...

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. more...

Purpose: We evaluated whether measurements on conventional cephalometric radiographs are comparable to measurements on cone-beam computed tomography (CBCT)-constructed cephalometric radiographs taken from human skulls., Materials and Methods: The CBCT scans and conventional cephalometric radiographs were made using 40 dry skulls. With I-Cat Vision software (Imaging Sciences International, Inc, Hatfield, PA), a cephalometric radiograph was constructed from the CBCT scan. Standard cephalometric software was used to identify landmarks, and calculate distances and angles. The same operator identified 15 landmarks on both types of cephalometric radiographs on all images 5 times with a 1-week interval., Results: Intraobserver reliability was good for all measurements. The reproducibility of measurements on cephalometric radiographs obtained from CBCT scans was better, compared with the reproducibility of those on conventional cephalometric radiographs. There was no clinically relevant difference between measurements on conventional and constructed cephalometric radiographs., Conclusions: Measurements on CBCT-constructed cephalometric radiographs are comparable to conventional cephalometric radiographs, and are therefore suitable for longitudinal research. more...

Introduction: The aim of this retrospective observational case series study was to determine the morbidity of transmandibular Distraction Osteogenesis (DO) using a bone-borne distraction device to adapt the surgical protocol and improve hardware design., Patients and Methods: The treatment of 23 consecutive, non-syndromic patients who underwent transverse mandibular DO after a midline symphyseal osteotomy with the TransMandibular Distractor (TMD ) was evaluated. The follow-up period lasted at least 1 year after the end of the contention period. Treatments were analysed according to the morphological and functional Success Criteria (SC) for Craniofacial Distraction Osteogenesis (CFDO) for patients with developmental dentofacial malformations established by the steering group of European Collaboration on Cranial Facial Anomalies (EUROCRAN)., Results: Appropriate distraction was obtained in 22 of the 23 patients. One patient had irreversible dentition damage, consisting of an inadvertent apical section. All other SC for CFDO were fulfilled 100% at 1 year follow-up. Seven patients suffered from short-term local infections during different phases of treatment. Two patients suffered subluxation of a central incisor that healed uneventfully. Local discomfort due to delayed union (in three patients) and trauma to the lower lip (one patient) were also observed., Conclusion: The main problems were high local infection rates and damage to an apex that required a root filling, as well as patient discomfort due to delayed union and/or the bulkiness of the TMD device. Based on the results of this morbidity study, modifications are recommended for both the surgical protocol and the TMD device hardware. more...

A detailed visualization of the interocclusal relationship is essential in a three-dimensional virtual planning setup for orthognathic and facial orthomorphic surgery. The purpose of this study was to introduce and evaluate the use of a wax bite wafer in combination with a double computed tomography (CT) scan procedure to augment the three-dimensional virtual model of the skull with a detailed dental surface. A total of 10 orthognathic patients were scanned after a standardized multislice CT scanning protocol with dose reduction with their wax bite wafer in place. Afterward, the impressions of the upper and lower arches and the wax bite wafer were scanned for each patient separately using a high-resolution standardized multislice CT scanning protocol. Accurate fitting of the virtual impressions on the wax bite wafer was done with surface matching using iterative closest points. Consecutively, 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 (Maxilim, version 2.0; Medicim NV, St-Niklaas, Belgium). Probability error histograms showed errors of < or =0.16 mm (25% percentile), < or =0.31 mm (50% percentile), and < or =0.92 (90% percentile) for iterative closest point surface matching. The mean registration error for automatic point-based registration was 0.17 +/- 0.07 mm (range, 0.12-0.22 mm). The combination of the wax bite wafer with the double CT scan procedure allowed for the setup of an accurate three-dimensional virtual augmented model of the skull with detailed dental surface. However, from a clinical workload, data handling, and computational point of view, this method is too time-consuming to be introduced in the clinical routine. more...

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. more...

Three-dimensional (3D) craniofacial imaging techniques are becoming increasingly popular and have opened new possibilities for orthodontic assessment, treatment, and follow-up. Recently, a new 3D cephalometric method based on spiral multi-slice (MS) computed tomography (CT) was developed and validated by our research group. This innovative 3D virtual approach is a bridge between conventional cephalometry and modern craniofacial imaging techniques and provides high-quality, accurate, and reliable quantitative 3D data. The aim of this article was to describe the advantages and the disadvantages of spiral MS-CT 3D cephalometry and to discuss the potential of cone-beam CT 3D cephalometry. more...

The purpose of this study was to present a new innovative three-dimensional (3-D) cephalometric method. Part I deals with the set-up and validation of a voxel-based semi-automatic 3-D cephalometric reference system. The CT data (DICOM 3.0 files) of 20 control patients with normal skeletal relationships were used for this study. To investigate accuracy and reliability of the 3-D cephalometric reference system (Maxilimtrade mark, version 1.3.0) a total of 42 (14 horizontal, 14 vertical and 14 transversal) orthogonal measurements were performed on each patient twice by each of two investigators. The intra-observer measurement error was less then 0.88 mm, 0.76 mm and 0.84 mm for horizontal, vertical and transversal orthogonal measurements, respectively. The inter-observer measurement error was less as 0.78 mm, 0.86 mm and 1.26 mm for horizontal, vertical and transversal orthogonal measurements, respectively. Squared correlation coefficients showed a high intra-observer and inter-observer reliability. The presented 3-D cephalometric reference system proved to be accurate and reliable and can therefore be used for 3-D cephalometric hard and soft tissue analysis. more...

Functional mandibular reconstruction after tumor resection is challenging. Currently, voxel-based craniofacial surgery and virtual planning of craniofacial surgical procedures are becoming increasingly popular. We report on a 56-year-old patient with an infiltrating recurrent squamous cell carcinoma of the mandible and buccal mucosa. Virtual resection of the mandible was accomplished using virtual reality techniques. Based on virtual geometric data, a metal template was configured for optimal contouration of a fibular bone graft while it was still pedicled in the donor field. Our operative procedure demonstrates the usefulness of voxel-based three-dimensional cephalometry in virtual planning of microsurgical bone transfer for mandibular reconstruction. more...

The purpose of this study was to investigate the effect of platelet-rich-plasma (PRP) on cranial distraction osteogenesis. Standardized calvaria critical size defects (6 cm x 5 cm) were created in 16 adult female sheep. Bifocal cranial transport distraction osteogenesis with autogenous free calvaria bone grafts (2 cm x 4 cm) was performed at a rate of 1mm once daily to a total of 30 mm. The 16 sheep involved in the experiment were randomly divided into four groups, four animals in each: Group 1 (no PRP, latency 5 days); Group 2 (no PRP, latency 0 day), Group 3 (PRP, latency 5 days) and Group 4 (PRP, latency 0 day). After a consolidation phase of 6 weeks, the animals were sacrificed and specimens harvested for conventional radiological and 3D quantitative computer tomographic (3D-QCT) assessment. New bone was generated in the distraction zone in all groups. There were significantly (P < 0.05) higher densities in the proximal region of the distraction regenerate in Group 4 (PRP, latency 0 day) compared to Group 2. However, no significant differences in mean density of the total distraction regenerate were found, neither in volume of the bony regenerate between the experimental groups. This study showed that PRP only had an effect on bone regeneration if active distraction was started immediately after application of PRP in the distraction gap. more...

This study presents a new method for objective assessment of the distraction regenerate using three-dimensional quantitative computer tomography (3D-QCT). The distraction specimens of 16 sheep that underwent bifocal cranial distraction osteogenesis to reconstruct a critical size defect were used to evaluate this method. To analyse the validity of this method the results were compared to conventional quantitative computer tomography (QCT). Squared correlation coefficients (r(2)) according to Sackett showed a high reliability (r(2) > 70% for the total DO regenerate, DO Regions 2-4). Method comparison according to Bland-Altman (< or =6.25% of measurements out of 95% limits of agreement) showed that three-dimensional computer tomography based bone densitometry is valid for future DO research. more...

Introduction: Several investigations over the past few years have shown that the importance of preserving the blood supply of the transport disc during segmental distraction has been overestimated. It was clearly demonstrated that distraction osteogenesis by local bone transportation could be achieved even with free bone grafts. So far, there have been no systematic investigations into how different types of free bone grafts vary in their function and suitability as transport discs in segmental craniofacial distraction. The aim of this study was to develop criteria to aid the clinician in selecting the most suitable free bone graft for distraction purposes., Materials and Methods: Under general anesthesia, calvarial defects measuring 6 x 5 cm were created in 12 adult black head sheep in order to reconstruct them by segmental distraction using two different types of bone grafts as transport discs. Group 1 (n=6) received autotopical membranous bone of the calvarium as the transport segment, while group 2 (n=6) received heterotopical enchondral material from the iliac crest. Distraction was started postoperatively after 5 days at 0.6 mm/day and continued for 7 weeks. After a further 6 weeks of consolidation, the animals were killed and specimens examined macroscopically, radiographically and histologically., Results: The significantly better quality of bone regenerates of group 1 was clearly influenced by the significantly better stability of the transport disc's connection to the distraction device, the calvaria grafts showing better volume stability and better mechanical resistance during transport than the iliac bone. The influence of both types of bone grafts on the macro- and microstructure of the newly formed bone was clearly evident. The mineralization density of group 2 regenerates was significantly lower than that of group 1 specimens., Conclusion: High mechanical stability of the bone graft is a very important point to consider when selecting a free graft for use as transport disc in local bone transport, especially if transport is necessary over long distances. more...

Bifocal transport osteogenesis (BTO) is a promising technique for the reconstruction of extended osseous craniofacial defects. Aim of this study was to determine the potential of this technique related to various donor sites of the transport segment. In 10 adult sheep critical size defects of the calvaria were treated by gradual movement of a transport segment consisting either of autogenous regional free calvarial bone grafts (n=5) or autogenous illiac free bone grafts (n=5). Latency period was 5 days; the rate of distraction was 1mm per day and extended approximately 40 days. The consolidation period was 28 days. After harvesting, specimens were investigated by conventional radiography, CT-scans, histologically and by fluorescence. In both groups transport osteogenesis resulted in a complete closure of the critical size defect. Membranous bone formation and remodeling occurred during the entire period of distraction and consolidation. The volumes and thickness of newly formed bone at the defect site were increased significantly when calvarial bone grafts were used (P<0.05). Iliac bone grafts became progrediently smaller during distraction, while the volume of calvarial grafts remained relatively constant (P<0.05). In conclusion, transport segments consisting of calvarial and iliac bone resulted in a reliable closure of craniofacial critical size defects in adult organisms; the application of calvarial bone grafts resulted in an increased extend of bone formation. more...

In previous intercenter studies on craniofacial morphology in patients with unilateral cleft lip and palate, probable surgical-induced changes in mandibular morphology and spatial position related to posterior vertical maxillary morphology were identified by our group. These changes could not be detected in other cephalometric cleft studies because posterior vertical maxillary height and vertical mandibular ramus length were not measured simultaneously. This study presents a modified digital lateral cephalometric hard and soft tissue analysis (Onyx Ceph software, version 2.5.6.; Image Instruments GmbH, Chemnitz, Germany) to evaluate craniofacial morphology and growth patterns in patients with clefts. Forty controls without clefts were used to evaluate the accuracy, reliability, and validity of this analysis for future cleft research. Measurement error according to the method of Bland and Altman was less than 1.00 degrees and 1.00 mm, whereas squared correlation coefficients (r) according to the method of Sackett et al showed a high reliability. Method comparison tests according to the method of Bland and Altman clearly showed that the modified digital cephalometric analysis ("test") was valid for future cleft research compared with the "gold standard" (conventional cephalometry). more...

The purpose of this study was to evaluate nasalance measures in German-speaking patients with different types of repaired cleft lip and palate and to find out if significant nasalance gender differences exist in the different cleft groups. A total of 125 German-speaking cleft patients (74 male and 51 female) were included in this study: 18 patients with isolated unilateral cleft lip (UCL; mean age: 13.00 +/- 2.03 years), 66 patients with complete unilateral cleft lip and palate (UCLP; mean age: 14.80 +/- 3.45 years), 25 patients with isolated cleft palate (CP; mean age: 14.60 +/- 3.48 years), and 16 patients with complete bilateral cleft lip and palate (BCLP; mean age: 14.30 +/- 3.61 years). Nasalance data were collected and computed using the NasalView hardware/software system (Fa. Tiger Electronics, Seattle, WA). Speech stimuli according to a modified Heidelberg Rhinophonia Assessment Form (sustained vowels "a," "e," "i," "o," and "u"; oral and nasal sentences; and three oral-nasal reading passages) were used to obtain nasalance scores. Nasalance distance and ratio were also calculated for the oral and nasal sentences and for one of the oral-nasal reading passages. Unpaired t tests showed no significant gender nasalance differences in each cleft group. Analysis of variance showed no significant differences in mean nasalance distance and ratio. For the nasal sentence, a significant difference (P = 0.032) in mean nasalance scores was found between the UCL and UCLP groups. more...

Patients with unilateral cleft lip and palate (UCLP) can present with an asymmetric transversal deficiency caused by collapse of the lateral maxillary segment at the cleft side. The surgical technique and orthodontic implications of segmental unilateral transpalatal distraction (TPD) after a posterior maxillary subapical osteotomy using the transpalatal distractor (TPD(R)) are described. The differences between unilateral posterior surgical-assisted rapid palatal expansion (SA-RPE) and segmental unilateral TPD are discussed. The proposed orthodontic-surgical treatment strategy certainly has to be validated by long-term studies in the future. more...