Search

Purpose: Little is known about the three-dimensional (3D) transfer accuracy in maxillary repositioning procedures based on conventionally manufactured dental-mounted wafers. The purpose of the present study was a systematic 3D analysis for wafer-based maxillary positioning in orthognathic surgery., Materials and Methods: A total of 92 patients underwent Le Fort I in addition to mandibular bilateral sagittal split osteotomies (BSSO). Alignment of the pre- and postsurgical CBCT data sets allowed measuring maxillary position changes in axial, sagittal and transversal directions., Results: The highest achieved absolute transfer inaccuracies were 1.37 mm, ±0.84 in the sagittal direction, followed by 1.15 mm, ±0.69 in the axial, as well as 1.05 mm, ±0.79 in the transversal direction. The largest relative deviations could be found for repositions in the transversal plane (109.4%, ±4.5), followed by the axial (66.2%, ±51.5) and sagittal plane (49.3%, ±2.2). Significant transfer accuracy differences of repositioning procedures in the sagittal direction, mainly advancement procedures, could be detected if performed with (1.75 mm, ±0.90) or without (1.18 mm, ±0.78) additional rotational correction component. No significant differences were found between unidirectional and multidirectional maxillary correction procedures., Conclusion: The present study for the first time delivers systematic 3D accuracy data of wafer-based maxillary positioning procedures, attesting to its feasibility but also further encouraging the search for improvement strategies., (Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.)

It has been hypothesised that, in maxillary repositioning procedures, longer distances correlate with less accurate transfers and particularly the repositioning forces of facial skin and muscles that increase exponentially. However, this has not to our knowledge been confirmed. The purpose of this study was to search for differences in the accuracy of transfer from maxillary repositioning procedures parallel to the three orthogonal planes and with respect to three different anatomical landmarks of the first molar left and right (M1L and M1R) and the first incisor (I). Cone-beam computed tomography (CT) datasets taken before and after operation for 92 patients who had Le Fort I maxillary repositioning procedures were aligned to measure the changes in the maxillary position in the axial, sagittal, and transverse directions. Differences between planned distances and those achieved were calculated and analysed with Pearsons correlation coefficient. The strongest significant correlations between the extent of planned repositioning distances and achieved differences (error) were detected in the sagittal plane for the anatomical landmarks of the right (M1R) and left first molar (M1L). Correlations became weaker if a limited planned distance ranging from 0-4mm was compared with a complete observed range that reached up to 12mm. Our results show for the first time to our knowledge that the accuracy of transfer of wafer-based maxillary positioning procedures depends on the distance being moved. Longer distances correlate with less accuracy, particularly in the sagittal plane and in the first molar region., (Copyright © 2017. Published by Elsevier Ltd.)

There may well be a shift towards 3-dimensional orthognathic surgery when virtual surgical planning can be applied clinically. We present a computer-assisted protocol that uses surgical navigation supplemented by an interactive image-guided visualisation display (IGVD) to transfer virtual maxillary planning precisely. The aim of this study was to analyse its accuracy and versatility in vivo. The protocol consists of maxillofacial imaging, diagnosis, planning of virtual treatment, and intraoperative surgical transfer using an IGV display. The advantage of the interactive IGV display is that the virtually planned maxilla and its real position can be completely superimposed during operation through a video graphics array (VGA) camera, thereby augmenting the surgeon's 3-dimensional perception. Sixteen adult class III patients were treated with by bimaxillary osteotomy. Seven hard tissue variables were chosen to compare (ΔT1-T0) the virtual maxillary planning (T0) with the postoperative result (T1) using 3-dimensional cephalometry. Clinically acceptable precision for the surgical planning transfer of the maxilla (<0.35 mm) was seen in the anteroposterior and mediolateral angles, and in relation to the skull base (<0.35°), and marginal precision was seen in the orthogonal dimension (<0.64 mm). An interactive IGV display complemented surgical navigation, augmented virtual and real-time reality, and provided a precise technique of waferless stereotactic maxillary positioning, which may offer an alternative approach to the use of arbitrary splints and 2-dimensional orthognathic planning., (Copyright © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Purpose: To establish a basis for weighing the potential diagnostic and therapeutic benefits of three-dimensional cone-beam (CB) data sets in contrast to digital orthopantomography (OPG) and computerized tomography (CT) in implant dentistry., Materials and Methods: Twenty-seven patients requiring implant surgery received a single presurgical CB scan. A follow-up digital OPG was taken within a maximal postsurgical period of 2 weeks. For comparison purposes, a control group of 29 patients receiving CT as well as CB diagnosis was analyzed. Image quality of the different modalities was ranked retrospectively by five experienced examiners (from excellent to insufficient) for up to 10 defined criteria, including general image quality and several specific structures. The results were analyzed statistically, and interobserver agreement was calculated using intraclass correlation coefficients (ICCs)., Results: The median rating for all investigated criteria was good for CB imaging and between good and insufficient for OPG in the dental implant group. Except for general image quality, statistical analysis showed that CB imaging was significantly superior to OPG imaging for all investigated anatomic structures. With a few exceptions, all investigated anatomic structures in CT and CB imaging were rated excellent in the control group. No significant difference between CT and CB imaging was detected in the control group for all investigated criteria. With a few exceptions, ICCs were higher for CB images than for OPG. In the control group, ICCs for CT and CB images were similar, with a few exceptions., Conclusion: The results of the present study confirm superior radiographic visualization for all important high-contrast structures in presurgical implant dentistry assessment for CB imaging in contrast to OPG and a CT-like degree of information for high-contrast structures in CB data sets. Clinically, however, the elevated radiation dosages transmitted by CB imaging must be taken into account.