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Quelles sont , suivant vous, les analyses les plus utilisées ?
10/11/2012 à 11h11
Pour répondre a Kyll sur la céphalometrie et tissue moue. Une partie de mon projet de thèse, ce n'est pas la thèse définitive mais vue qu'il s'agit de la partie bibliographie il y aura probablement relativement peut de changement.
If good facial proportion had always been one of the goals of orthodontic treatment, soft tissue analysis had not been a major concern for the first orthodontist. The reason was that as Edmund H. Wuerpel (1866-1958) an art teacher at the Washington University School of Fine Arts explains to Angle who wanted to know what were the norm for facial harmony, that there is no rule for facial form[9]. What is considered harmonious by one observer can be consider disharmonious by another. On the other hand Angle was led by the belief that the human being as god creature had been created inherently perfect. As a consequence if all the teeth were place in proper occlusion as god intended, the dento alveolar base would be correctly positioned in relation to each other, this would lead to a correct positioning of the skeletal base which would in turn lead to a harmonious profile. This view had the advantage that defining rule for correct occlusion was far much easier and less controversial than for the soft tissue profile. Also even if growth modification was attempted it was not possible to know at the time to what extent the skeletal base had been affected. As a results study model were the main tools for the orthodontics treatment plan. Disharmonies in the profile were noted before treatment but the main goal of the treatment was to obtain a good occlusion of the teeth independently of the initial soft tissue situation. With the death of Angle, the school of extraction treatment began to flourish. The main reason for extraction was not for esthetic but for stability concern.
With the advent of the cephalostat it was possible to see the teeth (the primary body to receive the orthodontic force) in relation to the skeletal base. By superimposition it was possible to see the effect of treatment on the skeletal base (orthodontist were able to “see” that growth modification treatment had an impact on the skeletal base whereas class II elastics had mainly a dento-alveolar effect).
This leads to the integration of the cephalostat as one of the major tool for treatment planning. With the cephalometric analysis the main concern was the teeth and the skeletal base in what was an extension of Angle thinking. If the teeth and the skeletal base are in good position in relation to one another, the soft tissue will be in good position and the soft tissue profile should be harmonious. Quite early various publications show that this statement where probably untrue.
In 1958 Björk publish an article with tow subjects having approximately the same soft tissue profile but not the same skeletal profile, the same years Moorrees publish also an article in which two subject where having almost the same soft tissue profile but not same skeletal base thus putting in doubt the notion that the study of the skeletal base in itself was enough for making a diagnostic[10, 11]. Other article follow showing the shortcoming of the lateral cephalometric analysis as a main diagnostic tool, pointing out that different cephalometric analysis will provide different treatment plan for the same patient, even in case of diagnostic for an orthognatic surgery [12] and showing that the income could be unaesthetic even with good relation of the skeletal base as define by the cephalometric analysis [13, 14] .
But nevertheless in a study publish in 1991 Han show that the two main element for making a treatment planning were the study model and the cephalometric tracing, with the extra oral picture having an influence in less than 2% of the case [15]. More recently studies show that there was no real correlation between the evaluation success of the treatment by cephalometric analysis and the evaluation of the attractiveness when judging by picture [16],
Different soft tissue analysis were propose with time [17-20], but the dental and skeletal value stay the main elements used for diagnostic and treatment planning. It is an interesting testimony of the weight of the cephalometric analysis that all the soft tissues analyses which were proposed by orthodontist rely exclusively on a lateral X-ray to be performed. Certainly this allows to analysis to put in relation the soft tissue with the dental and skeletal elements which is not possible with an extra-oral picture, but at the same time an extra-oral picture allow for additional measurement. This limitation of soft tissue analysis was recognize by Arnett who use metallic maker in is study to increase the number of soft tissue points available [19]. Nowadays to arrive to the same results a simple cephalometric software can blend the cephalometric X-ray with the extra oral profile picture, but before the advent of the informatics and the possibility to change the dimension of the image, the difference of enlargement between the extra oral picture and the cephalometric made this method too imprecise when performed manually [21].
Another legacy of the importance of the cephalometry in the orthodontic field is the tendency to think in profile. For the patient the initial situation and the treatment results will be judged from the frontal view whereas the practitioner will judge mainly from profile. This can easily lead to some miscommunication. For example the clinician will be more sensitive to antero-posterior discrepancy then the patient, those discrepancies being much more noticeable in profile than in frontal view.
If really the profession wants to transit toward the soft tissue paradigm we should emphasis the study of the soft tissue from different view.
9. Pollock, H.S., Orthodontic profiles. Am J Orthod, 1958. 44: p. 382-4.
10. Björk, A., Some biological aspects of prognathism and occlusion of the teeth. Angle Orthod, 1951. 21: p. 3-27.
11. Moorrees, C. and M. Kean, Natural head position, a basic consideration in the interpretation of cephalometric radiographs. Am J Phys Anthropol, 1958. 16: p. 213-34.
12. Wylie, G.A., L.C. Fish, and B.N. Epker, Cephalometrics: a comparison of five analyses currently used in the diagnosis of dentofacial deformities. Int J Adult Orthodon Orthognath Surg, 1987. 2(1): p. 15-36.
13. Jacobson, A., Planning for orthognathic surgery--art or science? Int J Adult Orthodon Orthognath Surg, 1990. 5(4): p. 217-24.
14. Park, Y.C. and C.J. Burstone, Soft-tissue profile--fallacies of hard-tissue standards in treatment planning. Am J Orthod Dentofacial Orthop, 1986. 90(1): p. 52-62.
15. Han, K., Consistency of orthodontic treatment decisions relative to diagnostic records. Am J Orthod, 1991. 100: p. 212-9.
16. Oh, H.S., et al., Correlations between cephalometric and photographic measurements of facial attractiveness in Chinese and US patients after orthodontic treatment. Am J Orthod Dentofacial Orthop, 2009. 136(6): p. 762 e1-14; discussion 762-3.
17. Holdaway, R.A., A soft-tissue cephalometric analysis and its use in orthodontic treatment planning. Part I. Am J Orthod, 1983. 84(1): p. 1-28.
18. Arnett, G.W. and R.T. Bergman, Facial keys to orthodontic diagnosis and treatment planning. Part I. Am J Orthod Dentofacial Orthop, 1993. 103(4): p. 299-312.
19. Arnett, G.W., et al., Soft tissue cephalometric analysis: diagnosis and treatment planning of dentofacial deformity. Am J Orthod Dentofacial Orthop, 1999. 116(3): p. 239-53.
20. Bergman, R.T., Cephalometric soft tissue facial analysis. Am J Orthod Dentofacial Orthop, 1999. 116(4): p. 373-89.
21. Phillips, C., et al., Photocephalometry: errors of projection and landmark location. Am J Orthod, 1984. 86(3): p. 233-43.
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