PubMed · 11862934
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J Treil, B Waysenson, P Borianne, J Casteigt, J Faure, A Horn. 2001. Three-dimensional cephalometry.. https://pubmed.ncbi.nlm.nih.gov/11862934/
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OBJECTIVE: this study was aimed at characterizing the craniofacial structures, i.e. the facial skeleton, cranial base, dentition, pharyngeal airway space, and the hyoid bone position, in healthy preschool children without sleep-related breathing disorder. MATERIALS AND METHODS: from lateral cephalometric radiographs taken of 92 children for diagnostic purposes, 45 were selected for the present investigation on the basis of head position, and divided according to the classification of Siriwat and Jarabak (Angle Orthod. 55 (1985) 127) into groups representing counter-clockwise (CC), straight downward (SD), and clockwise (C) facial types. RESULTS: the findings showed that, in comparison with the other groups, CC is associated with larger facial taper and posterior facial height, smaller mandibular line angle, ramus position, lower facial height and cranial base angle. By a similar comparison, C is associated with larger mandibular line, gonial angles and convexity, and with a smaller L-1 to mandibular line angle. There were no significant differences in hyoid bone position among the three groups. However, the distance of the lower pharynx was smaller in CC than in C, while the tongue base of CC was noted to be in a posterior position. CONCLUSIONS: thus, the results indicate that there are significant differences in the madibular position and form among the present three groups of children. It is proposed that the objective of vertical facial control ought to be included in the treatment of preschool children with malocclusion and respiratory disorder.
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BACKGROUND: Computer-aided virtual three-dimensional (3D) surgical simulation assists the necessary visual understanding of complex pathological situations but has so far been dependent on expensive hardware and software. METHOD: For the first time a non-commercial, user-orientated application for orthognathic and craniofacial surgical simulation has been introduced, based on freeware NIH Image 1.62 provided by the National Institute of Mental Health (NIMH). Use and limitations are demonstrated here by the example of hypertelorism surgery. The osteotomy lines and the amount of resection for outward positioning of the orbits were determined by the surgeon on a workstation using CT data. Possible movement patterns of the osteotomy fragments were rotations, sagittal and transversal movements or combinations of these. The program then allows the calculation of anatomical distances on the screen in a 1:1 relation. Normative values according to age and pathological anatomy determine the degree of displacement. The program calculates the new position of the osteotomy fragments and transfers the data of the segment movement to the original CT data. RESULTS: 3D visualization of bone and soft tissue contours have been produced with an acceptable quality on a workstation for the demonstration and visual understanding of the surgical plan. Evaluation of a postoperative CT showed that the amount of movement and size of bone resection in the simulation was slightly overestimated rather than underestimated. This was also dependent on the complexity of the pathological anatomy and on how experienced the surgeon was. CONCLUSION: The use of 3D simulation programs allows a better understanding of the pathological anatomy in all dimensions, and in many cases enables limitations to be recognized in advance. The public domain program makes a major contribution to the quality of orthognathic and craniofacial surgical planning through cost-free usability, and supports continuous development and exchange of experience.