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Cephalometrics, cephalometrists, and orthodontics
Editorial Cephalometrics, Cephalometrists, and Orthodontics
T
HAT ccphalometrics is changing the orthodontic perspective, no one wilt deny. Vet, the greater segment of clinical orthodontists are hard put 1,~) l’ollow with a sufficient degree of accuracy the discussions of investigators in this field. Many orthodontists freely admit their failure to grasp the technique> if not also the practical value, of t,he application of crphalometrics in t,heir daily practice. At the fift,y-first annual session of the American Association of Orthodontists in San Francisco, which closed on May 12, 19:‘,5, cephalometrics WNS the underlying theme of practically every one of the essays and most of the research reports presented. Articles on cephal&netrics now constitute the vast majority of papers submitted for publication in the AMERICAN JOURNAL UF ORTHODOXTICS. Were the JOURNAL to attempt to publish all these contributions, the editor would find the space available to him pre-empted bp this subject for months to come and the rcadcrs of the .JOTRI-AL would find themselves hopelessly confused. Lest. the uninitiated practitioner become discouraged when he reads articles or sits at meetings and listens to supercharged statistical discussions that woultl tax the faculties of t,he specialis:t in biostatistics, we quote hrirfl) from the field of physical anthropology. I,e Gras (‘lark, professor of anat,omy at the Irniversity of Oxford. Enpland. a. well-known a.uthority in paleoanthropology, calls attention, in his recent. book.” to the fallacies which oc(dur in the quantitative assessment of Clark includes t,he following of interest to orthotaxonomic relationships. dontists : I . “The fallacy of relying on ina.dcquatc statistical data.” 3.a. “The fallacy of treating all metrical data as of equal t,axonomic value. ” 3. “The fallacy of treating cha,racters separately and independently, inst.ead of in combination.” treat4. “The fallacy of inadequate or il~accurate statistical ment. ” 5. The fallacy of failure to adhere to “the principle of morphological equivalence in making statistical comparisons. ” *Ix Gras Clark, W. E.: The Fossil Evidence for Humxn Evolution. An Introrluc~tim tc, the Study of Paleoanthropology, Chicago, 1955, The ITniversity of Chicago Press.
709
710
EDITORIAL
6. “The fallacy of comparing skeletal elements in individuals of different age, sex and size.” 7. “The fallacy of comparing measurements taken by different observers using different techniques. ” 8. “The fallacy of relying for assessment of ahtinities on biometrical analysis of characters which may have no genetic basis.” If the foregoing fallacies can be avoided, the next question is: What are we measuring and what is the significance of such measurements1 Kherumian,* a physical anthropologist, submits a table of craniometric and anthropometric measuring points, to which he adds: “It is necessary to prescribe a system of exact landmarks which will permit searching analysis of human morphological characters, as much for the skeleton as for the soft parts. Such a system of ‘morphologic points’ does not exist . . . it remains for a future Congress of specialists to eliminate superfluous points and harmonize others. ” BjGrk, one of the outstanding contributors to the study of cephalometrics, and Palling** caution the orthodontist who would rely on cephalometrics as follows : “The value of biometrical methods in clinical diagnosis depends entirely on the user’s appreciation of the limitations inherent in the method. Cephalometric methods of analysis, especially growth analysis, can be extremely valuable but presuppose a thorough knowledge of normal and anomalous growth and development and how to interpret biometrical methods. Failing this, such methods may prove difficult to understand and may even be misleading. ’’ The biometric study of large numbers of children through cephalometric methods has provided us with an insight into the human growth pattern of the face and jaws. Attempts also have been variously made to employ cephalometric findings as diagnostic criteria. The question now arises as to how valid are cephalometric measurements in planning diagnosis. Lundstriim”“” is of the opinion that “the clinical importance of cephalometric determinations is a question that cannot be considered sufficiently investigated.” Perhaps the major point of agreement among the cephalometrists on this side of the Atlantic is the fact that clinical diagnosis along cephalometric determinations entails the weighing of many measurements which tend to modify each other and may even cancel out their respective contributory significance in the evaluation of the facial pattern as found in the individual patient. et anthropom6triques. Rev. *Kherumian, R. : RBpertoire des points cramometriques Morpho-Phelpiologie F$umaine, No. 2, p. 22, 1949 (Abstracted in Am. J. Phys. Anthropol.). **BjGrk, A.. and Palling, M.: Adolescent Age Changes in Sagittal Jaw Relation, Alveolar Prognathy, and Incisal Inclination, Acta Odontol. scandinav. 12: 201-232, 1955. *:*Lundsttim, A. : Cephalometric Registrations as an Aid in Diagnosing Malocclusions. Angle Orthodontist 24: 8-14, Jan., 1954.
EDITORIAL
Til I
In a recent paper,” we called attention to t,he fact that the importallt element which is still lacking in so far as the use of cephalometrics as positive diagnostic criteria in orthodontics is concerned, is a “normal range” of values about the various standard mean measurements employed, to be used as a base line. The use of mean measurements as diagnostic bases can be dangerous and the significance of standard deviations frequently is confusing to thtl practitioner who is not too familiar with the statistical method. We also pointed out, in the same paper, that any measurements obtaincci in an individual child which fall outside the standard i’llnrmal range,” whett such is established, would then have to be associated wit,h an abnormal condition of dentofacial growth and malocclusion of the t.eeth and should not, be fount1 in association with normal dcntofacial growth and normal tlelltwl occlusion. Since the various lines and angles measured in cephalometric studic+ are known to exhibit an extremely wide range of variation about their mean. it becomes an almost insurmountable task to evaluate t,heir relative diannosbic significance. The situation, however, is far from a hopeless one. 1'1~ the contrary, it holds forth much promise for the orthodontics of the futurcb. Whether this future promise will be realized depends largely on the initiat,ivt of the orthodontists themselves. What is needed is a common meeting ground on which representatives 01 the various disciplines concerned would study the cephalometric problem tit formula,te basic principles as a guide to workers in t.his field and to &ablish criteria for testing findings so obtained. We do not refer to holding a “symposium,” where each of the participants is anxious to defend his thesis. It is proposed, rather, that a “work shop” be held. Among those who might 1~ invited to such a “workshop!* should bc physical anthropometrists, biometricians, anatomists, ant1 orthtrdontists. The persons invited should be briefed in advxnce and given time* to prepare statements; their statements should be studied by the participa.nis before the “workshop” is convened. The report emanating from such :i group could not be expected to bring about a complete and immcdiatch solution of the problem, but it would certainly go a long way towartl brinpilrg a,bout a bet.ter understanding of the problem itself. For the practitioner 01 ort,hodontics, it would provide a point of orientation which would aid hi111 in understanding a,nd applying ctepha,lornc~t ric findings. The AlllP~ic*iltt L\s.. sociation of Orthodontists might well consitltbr tho foregoing suggesticjn (I~IC of its responsible concerns.
*Sa!zmann, J. A., and Ast. D. B.: The Newburgh-Kingston Caries Fluorine y&tofaclal Growth and Development-Cephalometric Study, Am. J. Orthodontics
Study. IX. 41: 674-590,
T
HAT ccphalometrics is changing the orthodontic perspective, no one wilt deny. Vet, the greater segment of clinical orthodontists are hard put 1,~) l’ollow with a sufficient degree of accuracy the discussions of investigators in this field. Many orthodontists freely admit their failure to grasp the technique> if not also the practical value, of t,he application of crphalometrics in t,heir daily practice. At the fift,y-first annual session of the American Association of Orthodontists in San Francisco, which closed on May 12, 19:‘,5, cephalometrics WNS the underlying theme of practically every one of the essays and most of the research reports presented. Articles on cephal&netrics now constitute the vast majority of papers submitted for publication in the AMERICAN JOURNAL UF ORTHODOXTICS. Were the JOURNAL to attempt to publish all these contributions, the editor would find the space available to him pre-empted bp this subject for months to come and the rcadcrs of the .JOTRI-AL would find themselves hopelessly confused. Lest. the uninitiated practitioner become discouraged when he reads articles or sits at meetings and listens to supercharged statistical discussions that woultl tax the faculties of t,he specialis:t in biostatistics, we quote hrirfl) from the field of physical anthropology. I,e Gras (‘lark, professor of anat,omy at the Irniversity of Oxford. Enpland. a. well-known a.uthority in paleoanthropology, calls attention, in his recent. book.” to the fallacies which oc(dur in the quantitative assessment of Clark includes t,he following of interest to orthotaxonomic relationships. dontists : I . “The fallacy of relying on ina.dcquatc statistical data.” 3.a. “The fallacy of treating all metrical data as of equal t,axonomic value. ” 3. “The fallacy of treating cha,racters separately and independently, inst.ead of in combination.” treat4. “The fallacy of inadequate or il~accurate statistical ment. ” 5. The fallacy of failure to adhere to “the principle of morphological equivalence in making statistical comparisons. ” *Ix Gras Clark, W. E.: The Fossil Evidence for Humxn Evolution. An Introrluc~tim tc, the Study of Paleoanthropology, Chicago, 1955, The ITniversity of Chicago Press.
709
710
EDITORIAL
6. “The fallacy of comparing skeletal elements in individuals of different age, sex and size.” 7. “The fallacy of comparing measurements taken by different observers using different techniques. ” 8. “The fallacy of relying for assessment of ahtinities on biometrical analysis of characters which may have no genetic basis.” If the foregoing fallacies can be avoided, the next question is: What are we measuring and what is the significance of such measurements1 Kherumian,* a physical anthropologist, submits a table of craniometric and anthropometric measuring points, to which he adds: “It is necessary to prescribe a system of exact landmarks which will permit searching analysis of human morphological characters, as much for the skeleton as for the soft parts. Such a system of ‘morphologic points’ does not exist . . . it remains for a future Congress of specialists to eliminate superfluous points and harmonize others. ” BjGrk, one of the outstanding contributors to the study of cephalometrics, and Palling** caution the orthodontist who would rely on cephalometrics as follows : “The value of biometrical methods in clinical diagnosis depends entirely on the user’s appreciation of the limitations inherent in the method. Cephalometric methods of analysis, especially growth analysis, can be extremely valuable but presuppose a thorough knowledge of normal and anomalous growth and development and how to interpret biometrical methods. Failing this, such methods may prove difficult to understand and may even be misleading. ’’ The biometric study of large numbers of children through cephalometric methods has provided us with an insight into the human growth pattern of the face and jaws. Attempts also have been variously made to employ cephalometric findings as diagnostic criteria. The question now arises as to how valid are cephalometric measurements in planning diagnosis. Lundstriim”“” is of the opinion that “the clinical importance of cephalometric determinations is a question that cannot be considered sufficiently investigated.” Perhaps the major point of agreement among the cephalometrists on this side of the Atlantic is the fact that clinical diagnosis along cephalometric determinations entails the weighing of many measurements which tend to modify each other and may even cancel out their respective contributory significance in the evaluation of the facial pattern as found in the individual patient. et anthropom6triques. Rev. *Kherumian, R. : RBpertoire des points cramometriques Morpho-Phelpiologie F$umaine, No. 2, p. 22, 1949 (Abstracted in Am. J. Phys. Anthropol.). **BjGrk, A.. and Palling, M.: Adolescent Age Changes in Sagittal Jaw Relation, Alveolar Prognathy, and Incisal Inclination, Acta Odontol. scandinav. 12: 201-232, 1955. *:*Lundsttim, A. : Cephalometric Registrations as an Aid in Diagnosing Malocclusions. Angle Orthodontist 24: 8-14, Jan., 1954.
EDITORIAL
Til I
In a recent paper,” we called attention to t,he fact that the importallt element which is still lacking in so far as the use of cephalometrics as positive diagnostic criteria in orthodontics is concerned, is a “normal range” of values about the various standard mean measurements employed, to be used as a base line. The use of mean measurements as diagnostic bases can be dangerous and the significance of standard deviations frequently is confusing to thtl practitioner who is not too familiar with the statistical method. We also pointed out, in the same paper, that any measurements obtaincci in an individual child which fall outside the standard i’llnrmal range,” whett such is established, would then have to be associated wit,h an abnormal condition of dentofacial growth and malocclusion of the t.eeth and should not, be fount1 in association with normal dcntofacial growth and normal tlelltwl occlusion. Since the various lines and angles measured in cephalometric studic+ are known to exhibit an extremely wide range of variation about their mean. it becomes an almost insurmountable task to evaluate t,heir relative diannosbic significance. The situation, however, is far from a hopeless one. 1'1~ the contrary, it holds forth much promise for the orthodontics of the futurcb. Whether this future promise will be realized depends largely on the initiat,ivt of the orthodontists themselves. What is needed is a common meeting ground on which representatives 01 the various disciplines concerned would study the cephalometric problem tit formula,te basic principles as a guide to workers in t.his field and to &ablish criteria for testing findings so obtained. We do not refer to holding a “symposium,” where each of the participants is anxious to defend his thesis. It is proposed, rather, that a “work shop” be held. Among those who might 1~ invited to such a “workshop!* should bc physical anthropometrists, biometricians, anatomists, ant1 orthtrdontists. The persons invited should be briefed in advxnce and given time* to prepare statements; their statements should be studied by the participa.nis before the “workshop” is convened. The report emanating from such :i group could not be expected to bring about a complete and immcdiatch solution of the problem, but it would certainly go a long way towartl brinpilrg a,bout a bet.ter understanding of the problem itself. For the practitioner 01 ort,hodontics, it would provide a point of orientation which would aid hi111 in understanding a,nd applying ctepha,lornc~t ric findings. The AlllP~ic*iltt L\s.. sociation of Orthodontists might well consitltbr tho foregoing suggesticjn (I~IC of its responsible concerns.
*Sa!zmann, J. A., and Ast. D. B.: The Newburgh-Kingston Caries Fluorine y&tofaclal Growth and Development-Cephalometric Study, Am. J. Orthodontics
Study. IX. 41: 674-590,