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Preliterate environment and the nasopharynx
Preliterate environment the nasopharynx Charles
and
B. Preston,
Johannesburg,
South
Africa
M
outhbreathing caused by an obstructed airway has been associated with Class II malocclusion, buccal cross-bite, low tongue position, and vertical growth problems.’ Enlarged adenoids, inadequate development of the nasal airway, and soft-tissue swelling resulting from allergies are possible causes of nasopharyngeal obstruction. The nasopharynx consists of a group of muscular organs, and its size and shape depend largely on the surrounding bony structures which, for the most part, are the bones of the base of the cranium.’ With the improvement in x-ray techniques and the advent of laminagraphy, it is possible to study the anatomy of the nasal airway and throat.3 Such studies”, 4 show that the amount of adenoid tissue present must be assessed relative to the dimensions of the nasopharynx. Heredity plays an important role in determining the size and shape of the human face and thus of the airway.” However, environment appears to play a major part in the etiology of nasal obstruction. Marks” states that the sensitization of nasal mucous membranes from early feeding of cow’s milk gives rise to persistent edema. Cow’s milk in the neonatal period may be a priming, sensitizing factor which propels the allergic infant toward progressively severe allergic manifestations, one of which may be dentofacial deformity.6 Preliterate peoples are said to be comparatively free from allergic diseases. Balyeat and Bowen’ remarked on the paucity of allergic manifestations and dentofacial abnormalities in preliterate peoples, such as the Oklahoma Indians. Sincock” stated that he had never seen Chippewa Indians with hay fever, asthma, or eczema. He attributed these findings to the fact that Indian babies were breast-fed for fully 9 months or longer without supplemental foods or water. When early feeding of cow’s milk and adult foods was introduced, eczema and other allergic manifestations appeared. The object of the present study was to investigate the linear dimensions of the nasal passages in preliterate peoples, such as the Lengua Indians of South America and the Sushmen (San) of southwest Africa. A second aim of the study was to determine the degree of soft-tissue, particularly adenoidal tissue, encroachment on the nasopharyngeal airway space of these peoples. Materials
and methods
The Lengua Indians (Pig. 1A) inhabit the Gran Chaco of Paraguay and are considered to be primitive in their life style. The ethnography of the Chaco is described in great detail *Head and Associate Witwatersrand.
646
Professor,
Department
of Orthodontics,
C’JOZ-9416/79/120646+11$01
School
of Dentistry,
.lOiO 0
Universityof the
1979 The C
V. Mosby CO.
l’olumr 76 Number 6
Preliterate
Fig.
Fig.
IA.
16.
Lengua
female.
Bushman
male.
environment
and
nasophaqm
647
by Men ‘aux , ’ o while Grubb” published a comprehensive monograph on a single Chaco tribe. Tilhe In dian tribes of the Chaco have remained culturally intact 1well into the: twentieth cei‘itury : long after most other Amerindian cultures have dissolve:d.r2 A recent estimate of the C:haco tribal population is 27,000, of which 3,000 to 4,000 1are Lengua . I2 The Lengua have typical Mongoloid features, as described by Bj6rk.13, l4 The Bus1hmen (Fig. 1B) of southwest africa, like the Lengua Indians of South
648
Am. J. Orthad Decrmber 1919
Preston
NS
Fig.
2. Cranial
landmarks.
America, have little contact with modern society, and they provide us with a remarkable view of a present-day society living in a Stone Age cultural context.‘j The investigation was undertaken on 82 Lengua Indians (48 females and 34 males) as well as 71 Bushmen (39 females and 32 males). The Lengua Indians studied were born at and live in the vicinity of Makthlawaiya, a settlement approximately 160 statute miles north of Asuncion, where there is a mission station run by the Sociedad Misionera en Sud America. The ages of all but a few of the Indians were obtained from the records of the mission station. The Bushmen studied live in the northwestern parts of southwest Africa in close proximity to a small medical outpost. It was impossible to determine their ages accurately, but all were adults with fully erupted permanent dentitions. Lateral cephalometric radiographs were taken of all the subjects included in the study. These radiographs were taken at a 5foot target-to-film distance, and they were all developed on site. Ail measurements were derived from tracings of the lateral cephalometric films. Linear measurements were read to the nearest 0.5 mm. and angular measurements to the nearest 0.5 degree. The measurements were all performed by the same operator but were repeated after an interval to determine and to limit the degree of error. The various anatomic reference points and planes used were previously defined by Ricketts’ and are illustrated in Figs. 2 and 3. From these reference points and planes, nine linear dimensions, three angles, and one percentage were determined. The length of the posterior cranial base is defined by the dimension sella to basion (S-Ba) (Fig. 2). The anteroposterior dimension of the pharynx is measured as the angle Ba-S-PNS and is also reflected by the dimension PNS-AA (AA is the most anterior point
Volumr 76 Number 6
Preliterate
Fig.
3. Anteroposterior
Fig.
4. Vertical
nasopharyngeal
nasopharyngeal
environment
and nasopharynx
649
measurements
measurements
on the anterior arch of the atlas) (Fig. 3). The vertical dimension of the nasopharynx is measured (Fig. 4) by the line which joins the spheno-occipital suture (SOS) to point IN (IN is the inferior end of the perpendicular from SOS to the line PNS-AA) and by the angle S-Ba-PNS. The amount of adenoid tissue present in each nasopharynx is represented by a percentage which equals the percentage of the line SOS-IN covered with lymphoid tissue (Fig. 5)? Schulhof’ recommended three additional measurements to determine the patency of the airway space (Fig. 6): 1. D-Ad1 : PNS: Distance from posterior nasal spine (PNS) to nearest adenoid tissue measured along the line posterior nasal spine-basion (PNS-BA). (Linder-Aronson4)
650
Am. J. Orrhod. December 1919
Preston
Fig.
5. Percentage
of adenoid
tissue
in the nasopharynx
2. D-Ad2: PNS: Distance from PNS to the nearest adenoid tissue measured along a line through PNS perpendicular to sella-basion (S-Ba). (Linder-Aronson”) 3. D-PTV: AD: Distance to the nearest adenoid tissue from a point on the pterygoid vertical (PTV) 5 mm. above PNS. The final group of measurements was designed to find the length and thickness of the soft palates and to determine their angular relationship to the hard palate. A line representing the long axis and length of the soft palate was drawn from the posterior nasal spine (PNS) to the most inferior point of the soft palate.2 Similarly, a line drawn from a point midway on the posterior-superior surface to a corresponding point on the anterior-inferior aspect of the soft palate represents its thickness .2 The angle formed by the line ANS-PNS and the long axis of the soft palate defined the angle of the soft palate.” Findings
The posterior cranial base of the Bushmen male has a mean length of 42.3 mm. (S.D. = 3.7; range 37.0 to 51.5), while the Bushman female has a value of 40.5 mm. (S.D. = 2.7; range 35.5 to 44.0) for this parameter. The Lengua Indians have posterior cranial bases which are slightly larger (males: x = 48.3 mm., S.D. = 3.5, range 41.0 to 57.0; females: -iT = 44.8, S.D. = 2.9, range 39.0 to 51.5) than those seen in the Bushmen. Lavelle17 studied 90 British male Caucasians 16 to 18 years of age. His sample was divided equally into the three major Angle occlusal categories. In these male subjects the mean posterior cranial base lengths varied between 45.7 mm. and 46.4 mm., the lower value belonging to Class III and the upper value to the Class II subgroups. The Lengua Indians have a relatively large mean ANB angle, which has been attributed to their short anterior cranial bases. l6 The morphology of the cranial base reflects facial features, which may be linked to race, and for this reason care must be taken in studying single dimensions of this area. However, when the lengths of the posterior cranial bases in the Lengua Indian, Bushman, and Caucasoid samples are compared, some perspective may be gained as to the relative sizes of skulls in these three races. According-
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Fig. 6. Dimensions
of the nasopharyngeal
environment
and nasopharynx
651
air space
ly, the Lengua and Caucasoid males have the largest skulls while the Bushmen have the smallest. The fact that the Bushmen have smaller skulls can be related to their short stature, as their heights vary between 140 cm. and 170 cm. for males, while females are generally a few centimetres shorter.1sa lg The next measurement was used to determine the relationship of the anterior arch of the atlas (AA) to the palatal plane which was represented by a posterior extension of the line PNS-ANS.’ A line drawn from point AA perpendicularly to the palatal plane indicated the relation of the palate to the atlas (Fig. 3). In the Lengua Indian male point AA is a mean distance of 8.2 mm. below the posterior extension of the palatal plane (S.D. = 3.8, range = 4.0 mm. above to 13.0 mm. below) and a mean distance of 4.6 mm. below in females (S.D. = 3.0, range = 2.0 mm. above to 13.0 mm. below). In the Bushman sample the mean measurements for this distance are smaller, although the ranges are similar (male: x = 6.0, S.D. = 3.4, range 3.5 mm. above to 14.0 mm. below; female: x = 6.65, S.D. = 3.6, range 4.0 mm. above to 13.0 mm. below). The relatively high values of the standard deviations recorded for this measurement may be due to difficulties encountered in posturing the subjects correctly in the cephalostat. It was not possible to communicate directly with the Lengua Indians and the Bushmen, and instructions were given by sign language and example. Ricketts’ studied twenty persons with an average age of 12% years, the majority of whom exhibited Angle Class II malocclusions. In this sample he found that AA was between 1.0 mm. and 15.0 mm. below the posterior extension of the palatal plane. The mean distance was 10.0 mm. below the palatal plane, which is a higher value than is recorded for the same dimension in the Lengua Indians and Bushmen. The Lengua Indians have Mongoloid facial features. l6 All subjects in the present sample have Angle Class I occlusions and, from the lengths of their posterior cranial bases, have different skull sizes
652
Am. i. Urthod.
Preston
Table
Drcrmbrr
1. Dimensions of the nasopharynx PNS-AA (mm.1
Caucasoid male Lengua male Lengua female
% 42.0 (33.0-55.0) ?t 38.76 s 4.91 (30.0-52.0) x 35.33 S 3.24 (29.0-43.0)
Bushman x 41.96 male
s 5.73 (34.0-55.0)
Blishman x 40.56 female
1979
S 4.36 (30.0-50.0)
*
6a.S. PNS* (degrees) x61.0 (52.0-69.0) x 58.45 s 5.43 (48.0-68.0) x 59.86 S 4.76 (52.0-53.0) x 65.87 S 6.46 (58.0-84.0) x65.16 s 5.18 (50.0-75.0)
SOS-IN* (mm.)
S.Ba. PNS* (degrees)
D-ADI:PNSt (mm.)
?t 27.0 (21 .O-31 .O) x 27.86 S 2.04 (23.0-32.0) x 25.91 s 2.08 (21.5-30.5) iT 22.71 S 2.39 (16.0-26.0) x21.46 s 1.97 (17.0-29.0)
% 63.0 (54.0-71 .O) x65.11 S 4.42 (57.0-80.0) % 66.40 S 5.68 (57.0-76.0) x 60.73 s 5.33 ;O.;.;;.O’
?t 26.32 S 4.28 x 30.13 s 2.80 (23.0-35.5) x 30.69 S 2.91 (24.0-39.0) x31.06 S 4.02 (26.0-37.5) x 29.51 S 4.24 (15.5-34.5)
%= Mean. S = Standarddeviation. NR = Not reliable. Rangeof measurement is shownin parentheses. *RickettsmixedCaucasoid sample mean age, 12’% t Schulhof mixed Caucasoid sample age range, 6 to
s 4.15 (52.0-71.5)
D-AD2:PNSi (mm.1 x21.78 S 4.67 % 27.07 s 3.41 (17.0-35.5) % 29.29 S 3.22 (22.5-39.0) ?i 24.64 s 3.40 (19.0-3 I .O) x 22.80 s 3.99 (13.0-31.0)
D-PW:AD: x 14.56 s 4.70 % 20.48 NR x 22.22 NR NR
NR
years. 12 years.
as compared to Caucasians. These factors may affect the relationship of point AA to the palatal plane and may account for differences in nasopharyngeal morphology between the peoples were ull preliterate groups and the Caucasoid sample of Ricketts. ’ Thepreliterate adults, while the male Caucasoid samples of Rickett? and Schulhof’ included young children.
Examination of the cephalometric radiographs revealed that two of the Bushmen and two Indians had enlarged adenoid masses in their nasopharynges. The enlargements were not sufficient to obstruct their airway spaces. The dimensions of the nasopharyngeal spaces are set out in Table I. The anteroposterior depth (PNS-AA) of this area is largest in the Caucasoid sample and smallest in the Lengua females. The anteroposterior measurement in the Bushmen (PNS-AA) closely approximates that of the Caucasoids, while the angular measurement Ba-S-PNS confirms that the Bushmen have relatively deep nasopharyngeal air spaces. The Bushmen, however, have smaller vertical nasopharyngeal dimensions (SOS-IN, S-Ba-PNS), as is reflected in Table I. The measurements suggested by Schulhof have been found to be significant at the 0.05 level when mouth breathers were compared with non-mouth breathers.’ Three of the suggested measurements are recorded in Table 1, and they illustrate the following features: The Lengua Indians have high values for these measurements, indicating reduced amounts of soft tissue in this region and the presence of large airway spaces. Considering the smaller skulls of the Bushmen, they too have larger airways when compared to the sample of Caucasoids.’ This is particularly true for the measurement D-Adl: PNS which reflects the relatively large anteroposterior nasopharyngeal size of the Bushmen (Table I). The measurement D-PTV: AD is not reliable in the samples of preliterate people because of the difficulty encountered in measuring this dimension accurately on standard lateral
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cephallometric radiographs. The adenoidal soft tissue is better defined in midsaggital laminagraphic section radiographs 2, 3 than in the standard lateral cephalographic radiographs used in the present study. The amount of adenoid tissue in the nasopharynx is represented by the percentage of soft tissue that is covered along the SOS-IN line.2 In Bushman males the mean percentage is 3.5.27(S.D. = 13.11,range 12.5 to71.1), whileinmales themeanpercentageis 37.38 (S.D. = 13.25, range 14.3 to 77.3). The percentages in the Lengua Indians are lower than those observed in the Bushmen, although the males in this instance appear to have slightly more soft-tissue intrusion into the nasal cavity than do the females (male: X = 31.21, S.D. = 10.58, range = 17.3 to 57.1; females: x = 25.84, S.D. = 9.24, range = 14.5 to 42.2). The ranges for this parameter are slightly smaller in the Lengua Indian:3 than in the Bushmen. The length of the soft palate varied in the Bushman males from a low of 29.0 mm. to a high value of 48.0 mm. (x = 36.14, S.D. = 4.01). In the Bushman females the mean length for this parameter is 34.02 mm. (S.D. = 3.57, range = 27.5 to 42.0). Corresponding values for the Lengua Indians are closely similar to those recorded in the Bushtnen (males: x = 39.19, S.D. = 4.53, range 30.0 to 50.0; females: X = 36.90, S.D. =z 3.05, range = 30.0 to 43.0. The average thickness of the uvula in male Bushmen is 9.32 mm. (S.D. = 1.36, range 7.5 to 13.5) and in female Bushmen the mean thickness is 8.67 mm. (S.D. = 1.2, range 7.0 to 11.5). The Lengua Indians have slightly higher values for uvular thickness (males: X = 10.10, S.D. = 1.38, range 7.0 to 12.0; females:X = 10.29, S.D. = 1.09, range 8.0 to 12.5). The angle of the uvula in Bushman males ranges from a low of 33 degrees to a high of 57 degrees (X = 45.45, S.D. = 7.54). In Bushman females the mean uvular angle is 44.03 degrees (S.D. = 6.73, range 27.0 to 53.0). The uvular angle observed in the Lengua. Indians is higher than that recorded for the Bushmen (males: x = 53.66, S.D. = 4.16, range = 45.0 to 67.0; females: x = 50.27, S.D. = 6.36, range 40.0 to 63.6). Discussion
The Lengua Indians have Mongoloid facial features, as described by Bjork,‘“, I4 and this factor may influence the anatomic shape of their nasopharyngeal regions. From the lengths of the posterior cranial bases, it would appear that there are also slight differences in skull size between the samples. The skeletal elements of the skull and cervical vertebrae control the size and shape of the soft-tissue pharynx, which is literally a group of muscular organs. Differences in the bony structures may thus markedly influence the soft-tissue dimensions as used by Schulhof. ’ In assessing the values recorded in Table I, morphologic differences between the races studied must be kept in mind. The Lengua Indians have relatively small mean anteroposterior dimensions (PNS-AA, Ba-S-PNS) of the bony nasopharyngeal areas, while the Bushmen have comparatively high values for these parameters (Table I). The converse holds true for the vertical measurements (SOS-IN, S-Ba-PNS). The primitive races have relatively high values for the dimensions D-AD1 : PNS and D-AD2:PNS when compared to the sample of Caucasoids.’ These measurements again show that the Bushmen have deep nasopharyngeal air spaces, while the Lengua Indians
6
Preston
Am. J. Orthud. December 1979
have relatively less anteroposterior development for this region. The Lengua Indians, however, compensate by having greater vertical growth in this area. The effective airway spaces are thus greater in the two preliterate tribes than in the Caucasoid’ sample. The Caucasoids’. ’ who constitute the control in this study were selected from an age group in which the adenoids are at their maximal size. The nasopharynx provides space on its posterior wall for lymphoid tissue which often hypertrophies during childhood and which is then recognized as the “adenoids, ‘~~3 23 Anatomically, the pharyngeal tonsils or adenoids which appear at about the sixth month of fetal life as a subepithelial infiltration of lymphocytes lie on the roof and upper posterior wall of the nasopharynx.24, 25 In the adenoid tissue the lymphoid nodules are directly under the epithelium and, in view of their extensively cryptic structure, offer a wide area of contact between these two structures. The adenoidal lymphoid tissue is thought to play a major role in antibody production since its nodules are separated from the oral cavity by only a layer of epithelium and it is thus constantly exposed to bacterial contact. 23 The adenoids follow a lymphoid tissue growth pattern and reach nearly 200 percent of adult size at the age of 12 years. Their size then undergoes a sharp decrease until it is reduced to 100 percent attainment at the age of approximately 20 years.‘6 The samples of preliterate peoples were selected from Lengua Indian adults who had a maximum age of 55 years (male: X = 35 years; female: x = 39 years) and from adult Bushmen with full permanent dentitions. It may thus be expected, on the basis of age, that the amounts of lymphoid tissue in the Caucasoids and preliterate tribes could be different. The airway percentage may be expressed as the percentage of nasopharynx occupied by adenoid tissue.“3 The technique suggested by Handelman requires somewhat sophisticated mathematical analysis. For the present study I have used the technique suggested by Ricketts2 to determine the extent of soft-tissue intrusion into the nasopharynx. The amount of adenoid tissue is represented by a percentage of tissue that is covered along the SOS-IN line. In the Caucasoid sample of Rickett? the average age was 12% years. In these children the maximum adenoid tissue was 92 percent of the SOS-IN dimension, while the low was only 19 percent. The mean of this measurement was recorded as 56 percent. In the Bushman male the mean percentage is 35.55 percent (S .D. = 13.11, range = 12.5 to 71. II), while in female the percentage for this parameter is slightly higher (x = 37.38, S.D. = 13.25, range = 14.28 to 77.27). In the Lengua Indians the percentages of soft-tissue encroachment on the airway space are considerably smaller (male: X = 31.21, S.D. = 10.58, range = 17.3 to 68.0; female: x = 25.84, S.D. = 9.24, range = 14.5 to 42.2). The findings indicate that the Bushmen and the Lengua Indians have less adenoid tissue than do the Caucasoid samples.” 2 The results also appear to support the contention that preliterate peoples are better equipped for nasal breathing.7. ’ It may be noted that Angle, 27in 1907, featured the faces of two adult male Plains Indians. He remarked on the balance in their faces and especially of their mouths, which are in perfect balance with the rest of their features. Angle27 was greatly influenced by George Catlin” who, in 1861, “thundered” against mouth breathing.‘$ Catlinz8 believed that mouth breathing resulted in a large number of psychosocial and dentofacial problems. None of the preliterate subjects had skeletal malocclusions which could be classified as being either Class II or Class III. I6 It is also recorded that none of them were mouth breathers or were at the time suffering from any allergic manifestations.
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It is difficult to draw any definite conclusions from this study, but the indications are that there is less soft-tissue encroachment into the nasopharynges of the two preliterate peoples studied than in the Caucasoid controls. As the Bushman and Lengua samples are not comparable to the Caucasoid samples with respect to age, further studies are required to determine normal values for younger groups of preliterates in order to make comparisons more meaningful. I would like to express my sincere appreciation to the Paraguayan Government, the South West African Administration, and the South African Medical Research Council for the assistance they gave me in undertaking this project. I would also like to thank the following people for their valued assistance: Professor A. Jacobson, Dr. V. Boettner, Dr. C. Perreira, and Professor J. F. van Reenen. Also, I wish to thank Mrs. R. Milstein for typing the manuscript. REFERENCES 1. Schulhof, R. .I.: Consideration of airway in orthodontics, J. Clin. Orthod. 12: 440-444, 1978. 2. Ricketts, R. M.: The cranial base and soft structures in cleft palate speech and breathing, Plast. Reconstr. Surg. 14: 47-61, 1954. 3. Ricketts, R. M.: Respiratory obstruction syndrome, AIM. J. ORTHOD. 54: 495-507, 1968. 4. Linder-Aronson, S.: Adenoids: Their effects on mode of breathing and airflow and their relationship to characteristics of facial skeleton and the dentition, Acta Otolaryngol. Suppl. 265: 1, 1970. 5. Krogman, W. M.: Forty years of growth research and orthodontics, AM. J. ORTHOD. 63: 357, 1973. 6. Marks, M. B.: Allergy in relation to orofacial dental deformities in children; a review, J. Allergy 36: 293-302, 1965. 7. Balyeat and Bowen: Quoted by Ricketts, R. M.: Respiratory obstruction syndrome, AM. J. ORTHOD. 54: 495-507, 1968. 8. Buettner-Janusch, J.: Physical anthropology: A perspective, New York, 1973, John Wiley & Sons, Inc., p. 98. 9. Sincock: Quoted by Ricketts, R. M.: Respiratory obstruction syndrome, AM. J. ORTHOD. 54: 495-507, 1968.
10. Metraux, A.: Ethnography of the Chaco. In Steward, J. H. (editor): Handbook of South American Indians, Bureau of American Ethnology, Bull. No. 143, Washington, D. C., (RepublishedNew York, 1963, Cooper Square) 1946, Smithsonian Institution, pp. 197.370. 11. Grubb, W. B.: An unknown people in an unknown land: An account of the life and customs of the Lengua Indians of the Paraguayan Chaco, with adventures and experiences during twenty years’ pioneering and exploration amongst them, ed. 2, London, 1911, Seely, Service & Co., Ltd. 12. Brown, S. M., Gajdusek, D. C., Leyshon, W. C., Steinberg, A. G., Brown, K. S., and Curtain, C. C.: Genetic studies in Paraguay: Blood group, red cell and serum genetic patterns of the Guayaki and Ayore Indians, Mennonite settlers and seven other Indian tribes of the Paraguayan Chaco, Am. J. Phys. Anthropol. 41: 317-344, 1974. 13. BjGrk. A.: The face in profile, Sven. Tandl%k. Tidskr. (Suppl). 40: 5B, 1947. 14. Bjb;rk, A.: Some biological aspects of prognathism and occlusion of the teeth, Acta Odontol. Stand. 9: l-40, 1950. 15. Tobias, P. V. (editor): The Bushmen, San Hunters and Herders of Southern Africa, Capetown and Pretoria, 1978, Human & Rosseau, pp. 1 l-12. 16. Jacobson, A., Preston, C. B., Boettner, V. A., and Pereira, C. B.: The craniofacial pattern of the Lengua Indians of Paraguay, Am. J. Phys. Anthropol. 47: 467-472, 1977. 17. Lavelle, C. L. B.: An analysis of the craniofacial complex in different occlusal categories, An. J. ORTHOD. 7: 574..582, 1977. 18. de Villiers, H.: The skull of the South African Negro: A biometrical and morphological study, Johannesburg, 1968, Witwatersrand University Press, 19. Singer, R.: The biology of the San. In Tobias, P. V. (editor): The Bushmen, 1978, Human & Rousseau Publishers, pp. 115-129. 20. Brodie, A. G.: On the growth pattern of the human head from the third month to the eighth year of life, Am. J. Anat. 68: 209, 1941.
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King, E. W.: A roentgenographic study of pbaryngeal growth, Angle Orthod. 22: 23-37, 1952. Rosenberger, A. C.: Growth and development of the naso-respiratory area in childhood, Ann. Otol. Rhinol. Laryngol. 43: 495-513, 1934. Handelman, C. S., and Osborne, G.: Growth of the nasopharynx and adenoid development from one to eighteen years, Angle Orthod. 46: 243-259, 1976. Van Alyea, 0. E.: The embryology of the ear, nose and throat, section on instruction, 1949. American Academy of Ophthalmology and Otolaryngology. Waldapfel, R.: The tonsil problem in the adult. Eye, Ear, Nose Throat Month. 30: 27, 1954. Baer, M. J.: Growth and maturation; an introduction to physical development, Cambridge, Mass., 1973, Howard A. Doyle, p. 7. Angle. E. H.: Treatment of malocclusion of the teeth, ed. 7, Philadelphia, 1907, S. S. White Dental Mfg. Co. Catlin, G.: The breath of life: Or mal-respiration and its effects upon the enjoyments and life of man, New York, 1861, John Wiley & Sons, Inc. (Reprinted in 1925 with preface by E. H. Angle.) Krogman, W. M.: The creativity of Edward H. Angle: Retrospect and prospect, Angle Orthod. 46: 209-218, 1976.
THE JOURNAL
50 YEARS
AGO
in twenty-five years years of infantile struggling, the orthodontic profession, as a whole, has yet been unable to throw off its swaddling clothes and in its efforts to overcome its limitations and failures grasps at fanciful theories and methods without any apparent analytic reasoning, and may be likened unto the proverbial drowning man and the straw. ‘Tis true we have striven for and almost reached mechanical perfection but with no apparent progress as to proved causative factors, no diminution of time in treatment or appreciable lowering in the percentage of failures, a sad commentary. (Robert Dunn: The international Journal of Orthodontia, Oral Surgery and Radiology, July, 1929.)
and
B. Preston,
Johannesburg,
South
Africa
M
outhbreathing caused by an obstructed airway has been associated with Class II malocclusion, buccal cross-bite, low tongue position, and vertical growth problems.’ Enlarged adenoids, inadequate development of the nasal airway, and soft-tissue swelling resulting from allergies are possible causes of nasopharyngeal obstruction. The nasopharynx consists of a group of muscular organs, and its size and shape depend largely on the surrounding bony structures which, for the most part, are the bones of the base of the cranium.’ With the improvement in x-ray techniques and the advent of laminagraphy, it is possible to study the anatomy of the nasal airway and throat.3 Such studies”, 4 show that the amount of adenoid tissue present must be assessed relative to the dimensions of the nasopharynx. Heredity plays an important role in determining the size and shape of the human face and thus of the airway.” However, environment appears to play a major part in the etiology of nasal obstruction. Marks” states that the sensitization of nasal mucous membranes from early feeding of cow’s milk gives rise to persistent edema. Cow’s milk in the neonatal period may be a priming, sensitizing factor which propels the allergic infant toward progressively severe allergic manifestations, one of which may be dentofacial deformity.6 Preliterate peoples are said to be comparatively free from allergic diseases. Balyeat and Bowen’ remarked on the paucity of allergic manifestations and dentofacial abnormalities in preliterate peoples, such as the Oklahoma Indians. Sincock” stated that he had never seen Chippewa Indians with hay fever, asthma, or eczema. He attributed these findings to the fact that Indian babies were breast-fed for fully 9 months or longer without supplemental foods or water. When early feeding of cow’s milk and adult foods was introduced, eczema and other allergic manifestations appeared. The object of the present study was to investigate the linear dimensions of the nasal passages in preliterate peoples, such as the Lengua Indians of South America and the Sushmen (San) of southwest Africa. A second aim of the study was to determine the degree of soft-tissue, particularly adenoidal tissue, encroachment on the nasopharyngeal airway space of these peoples. Materials
and methods
The Lengua Indians (Pig. 1A) inhabit the Gran Chaco of Paraguay and are considered to be primitive in their life style. The ethnography of the Chaco is described in great detail *Head and Associate Witwatersrand.
646
Professor,
Department
of Orthodontics,
C’JOZ-9416/79/120646+11$01
School
of Dentistry,
.lOiO 0
Universityof the
1979 The C
V. Mosby CO.
l’olumr 76 Number 6
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Fig.
Fig.
IA.
16.
Lengua
female.
Bushman
male.
environment
and
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647
by Men ‘aux , ’ o while Grubb” published a comprehensive monograph on a single Chaco tribe. Tilhe In dian tribes of the Chaco have remained culturally intact 1well into the: twentieth cei‘itury : long after most other Amerindian cultures have dissolve:d.r2 A recent estimate of the C:haco tribal population is 27,000, of which 3,000 to 4,000 1are Lengua . I2 The Lengua have typical Mongoloid features, as described by Bj6rk.13, l4 The Bus1hmen (Fig. 1B) of southwest africa, like the Lengua Indians of South
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NS
Fig.
2. Cranial
landmarks.
America, have little contact with modern society, and they provide us with a remarkable view of a present-day society living in a Stone Age cultural context.‘j The investigation was undertaken on 82 Lengua Indians (48 females and 34 males) as well as 71 Bushmen (39 females and 32 males). The Lengua Indians studied were born at and live in the vicinity of Makthlawaiya, a settlement approximately 160 statute miles north of Asuncion, where there is a mission station run by the Sociedad Misionera en Sud America. The ages of all but a few of the Indians were obtained from the records of the mission station. The Bushmen studied live in the northwestern parts of southwest Africa in close proximity to a small medical outpost. It was impossible to determine their ages accurately, but all were adults with fully erupted permanent dentitions. Lateral cephalometric radiographs were taken of all the subjects included in the study. These radiographs were taken at a 5foot target-to-film distance, and they were all developed on site. Ail measurements were derived from tracings of the lateral cephalometric films. Linear measurements were read to the nearest 0.5 mm. and angular measurements to the nearest 0.5 degree. The measurements were all performed by the same operator but were repeated after an interval to determine and to limit the degree of error. The various anatomic reference points and planes used were previously defined by Ricketts’ and are illustrated in Figs. 2 and 3. From these reference points and planes, nine linear dimensions, three angles, and one percentage were determined. The length of the posterior cranial base is defined by the dimension sella to basion (S-Ba) (Fig. 2). The anteroposterior dimension of the pharynx is measured as the angle Ba-S-PNS and is also reflected by the dimension PNS-AA (AA is the most anterior point
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Fig.
3. Anteroposterior
Fig.
4. Vertical
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measurements
measurements
on the anterior arch of the atlas) (Fig. 3). The vertical dimension of the nasopharynx is measured (Fig. 4) by the line which joins the spheno-occipital suture (SOS) to point IN (IN is the inferior end of the perpendicular from SOS to the line PNS-AA) and by the angle S-Ba-PNS. The amount of adenoid tissue present in each nasopharynx is represented by a percentage which equals the percentage of the line SOS-IN covered with lymphoid tissue (Fig. 5)? Schulhof’ recommended three additional measurements to determine the patency of the airway space (Fig. 6): 1. D-Ad1 : PNS: Distance from posterior nasal spine (PNS) to nearest adenoid tissue measured along the line posterior nasal spine-basion (PNS-BA). (Linder-Aronson4)
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Fig.
5. Percentage
of adenoid
tissue
in the nasopharynx
2. D-Ad2: PNS: Distance from PNS to the nearest adenoid tissue measured along a line through PNS perpendicular to sella-basion (S-Ba). (Linder-Aronson”) 3. D-PTV: AD: Distance to the nearest adenoid tissue from a point on the pterygoid vertical (PTV) 5 mm. above PNS. The final group of measurements was designed to find the length and thickness of the soft palates and to determine their angular relationship to the hard palate. A line representing the long axis and length of the soft palate was drawn from the posterior nasal spine (PNS) to the most inferior point of the soft palate.2 Similarly, a line drawn from a point midway on the posterior-superior surface to a corresponding point on the anterior-inferior aspect of the soft palate represents its thickness .2 The angle formed by the line ANS-PNS and the long axis of the soft palate defined the angle of the soft palate.” Findings
The posterior cranial base of the Bushmen male has a mean length of 42.3 mm. (S.D. = 3.7; range 37.0 to 51.5), while the Bushman female has a value of 40.5 mm. (S.D. = 2.7; range 35.5 to 44.0) for this parameter. The Lengua Indians have posterior cranial bases which are slightly larger (males: x = 48.3 mm., S.D. = 3.5, range 41.0 to 57.0; females: -iT = 44.8, S.D. = 2.9, range 39.0 to 51.5) than those seen in the Bushmen. Lavelle17 studied 90 British male Caucasians 16 to 18 years of age. His sample was divided equally into the three major Angle occlusal categories. In these male subjects the mean posterior cranial base lengths varied between 45.7 mm. and 46.4 mm., the lower value belonging to Class III and the upper value to the Class II subgroups. The Lengua Indians have a relatively large mean ANB angle, which has been attributed to their short anterior cranial bases. l6 The morphology of the cranial base reflects facial features, which may be linked to race, and for this reason care must be taken in studying single dimensions of this area. However, when the lengths of the posterior cranial bases in the Lengua Indian, Bushman, and Caucasoid samples are compared, some perspective may be gained as to the relative sizes of skulls in these three races. According-
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Fig. 6. Dimensions
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air space
ly, the Lengua and Caucasoid males have the largest skulls while the Bushmen have the smallest. The fact that the Bushmen have smaller skulls can be related to their short stature, as their heights vary between 140 cm. and 170 cm. for males, while females are generally a few centimetres shorter.1sa lg The next measurement was used to determine the relationship of the anterior arch of the atlas (AA) to the palatal plane which was represented by a posterior extension of the line PNS-ANS.’ A line drawn from point AA perpendicularly to the palatal plane indicated the relation of the palate to the atlas (Fig. 3). In the Lengua Indian male point AA is a mean distance of 8.2 mm. below the posterior extension of the palatal plane (S.D. = 3.8, range = 4.0 mm. above to 13.0 mm. below) and a mean distance of 4.6 mm. below in females (S.D. = 3.0, range = 2.0 mm. above to 13.0 mm. below). In the Bushman sample the mean measurements for this distance are smaller, although the ranges are similar (male: x = 6.0, S.D. = 3.4, range 3.5 mm. above to 14.0 mm. below; female: x = 6.65, S.D. = 3.6, range 4.0 mm. above to 13.0 mm. below). The relatively high values of the standard deviations recorded for this measurement may be due to difficulties encountered in posturing the subjects correctly in the cephalostat. It was not possible to communicate directly with the Lengua Indians and the Bushmen, and instructions were given by sign language and example. Ricketts’ studied twenty persons with an average age of 12% years, the majority of whom exhibited Angle Class II malocclusions. In this sample he found that AA was between 1.0 mm. and 15.0 mm. below the posterior extension of the palatal plane. The mean distance was 10.0 mm. below the palatal plane, which is a higher value than is recorded for the same dimension in the Lengua Indians and Bushmen. The Lengua Indians have Mongoloid facial features. l6 All subjects in the present sample have Angle Class I occlusions and, from the lengths of their posterior cranial bases, have different skull sizes
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Table
Drcrmbrr
1. Dimensions of the nasopharynx PNS-AA (mm.1
Caucasoid male Lengua male Lengua female
% 42.0 (33.0-55.0) ?t 38.76 s 4.91 (30.0-52.0) x 35.33 S 3.24 (29.0-43.0)
Bushman x 41.96 male
s 5.73 (34.0-55.0)
Blishman x 40.56 female
1979
S 4.36 (30.0-50.0)
*
6a.S. PNS* (degrees) x61.0 (52.0-69.0) x 58.45 s 5.43 (48.0-68.0) x 59.86 S 4.76 (52.0-53.0) x 65.87 S 6.46 (58.0-84.0) x65.16 s 5.18 (50.0-75.0)
SOS-IN* (mm.)
S.Ba. PNS* (degrees)
D-ADI:PNSt (mm.)
?t 27.0 (21 .O-31 .O) x 27.86 S 2.04 (23.0-32.0) x 25.91 s 2.08 (21.5-30.5) iT 22.71 S 2.39 (16.0-26.0) x21.46 s 1.97 (17.0-29.0)
% 63.0 (54.0-71 .O) x65.11 S 4.42 (57.0-80.0) % 66.40 S 5.68 (57.0-76.0) x 60.73 s 5.33 ;O.;.;;.O’
?t 26.32 S 4.28 x 30.13 s 2.80 (23.0-35.5) x 30.69 S 2.91 (24.0-39.0) x31.06 S 4.02 (26.0-37.5) x 29.51 S 4.24 (15.5-34.5)
%= Mean. S = Standarddeviation. NR = Not reliable. Rangeof measurement is shownin parentheses. *RickettsmixedCaucasoid sample mean age, 12’% t Schulhof mixed Caucasoid sample age range, 6 to
s 4.15 (52.0-71.5)
D-AD2:PNSi (mm.1 x21.78 S 4.67 % 27.07 s 3.41 (17.0-35.5) % 29.29 S 3.22 (22.5-39.0) ?i 24.64 s 3.40 (19.0-3 I .O) x 22.80 s 3.99 (13.0-31.0)
D-PW:AD: x 14.56 s 4.70 % 20.48 NR x 22.22 NR NR
NR
years. 12 years.
as compared to Caucasians. These factors may affect the relationship of point AA to the palatal plane and may account for differences in nasopharyngeal morphology between the peoples were ull preliterate groups and the Caucasoid sample of Ricketts. ’ Thepreliterate adults, while the male Caucasoid samples of Rickett? and Schulhof’ included young children.
Examination of the cephalometric radiographs revealed that two of the Bushmen and two Indians had enlarged adenoid masses in their nasopharynges. The enlargements were not sufficient to obstruct their airway spaces. The dimensions of the nasopharyngeal spaces are set out in Table I. The anteroposterior depth (PNS-AA) of this area is largest in the Caucasoid sample and smallest in the Lengua females. The anteroposterior measurement in the Bushmen (PNS-AA) closely approximates that of the Caucasoids, while the angular measurement Ba-S-PNS confirms that the Bushmen have relatively deep nasopharyngeal air spaces. The Bushmen, however, have smaller vertical nasopharyngeal dimensions (SOS-IN, S-Ba-PNS), as is reflected in Table I. The measurements suggested by Schulhof have been found to be significant at the 0.05 level when mouth breathers were compared with non-mouth breathers.’ Three of the suggested measurements are recorded in Table 1, and they illustrate the following features: The Lengua Indians have high values for these measurements, indicating reduced amounts of soft tissue in this region and the presence of large airway spaces. Considering the smaller skulls of the Bushmen, they too have larger airways when compared to the sample of Caucasoids.’ This is particularly true for the measurement D-Adl: PNS which reflects the relatively large anteroposterior nasopharyngeal size of the Bushmen (Table I). The measurement D-PTV: AD is not reliable in the samples of preliterate people because of the difficulty encountered in measuring this dimension accurately on standard lateral
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cephallometric radiographs. The adenoidal soft tissue is better defined in midsaggital laminagraphic section radiographs 2, 3 than in the standard lateral cephalographic radiographs used in the present study. The amount of adenoid tissue in the nasopharynx is represented by the percentage of soft tissue that is covered along the SOS-IN line.2 In Bushman males the mean percentage is 3.5.27(S.D. = 13.11,range 12.5 to71.1), whileinmales themeanpercentageis 37.38 (S.D. = 13.25, range 14.3 to 77.3). The percentages in the Lengua Indians are lower than those observed in the Bushmen, although the males in this instance appear to have slightly more soft-tissue intrusion into the nasal cavity than do the females (male: X = 31.21, S.D. = 10.58, range = 17.3 to 57.1; females: x = 25.84, S.D. = 9.24, range = 14.5 to 42.2). The ranges for this parameter are slightly smaller in the Lengua Indian:3 than in the Bushmen. The length of the soft palate varied in the Bushman males from a low of 29.0 mm. to a high value of 48.0 mm. (x = 36.14, S.D. = 4.01). In the Bushman females the mean length for this parameter is 34.02 mm. (S.D. = 3.57, range = 27.5 to 42.0). Corresponding values for the Lengua Indians are closely similar to those recorded in the Bushtnen (males: x = 39.19, S.D. = 4.53, range 30.0 to 50.0; females: X = 36.90, S.D. =z 3.05, range = 30.0 to 43.0. The average thickness of the uvula in male Bushmen is 9.32 mm. (S.D. = 1.36, range 7.5 to 13.5) and in female Bushmen the mean thickness is 8.67 mm. (S.D. = 1.2, range 7.0 to 11.5). The Lengua Indians have slightly higher values for uvular thickness (males: X = 10.10, S.D. = 1.38, range 7.0 to 12.0; females:X = 10.29, S.D. = 1.09, range 8.0 to 12.5). The angle of the uvula in Bushman males ranges from a low of 33 degrees to a high of 57 degrees (X = 45.45, S.D. = 7.54). In Bushman females the mean uvular angle is 44.03 degrees (S.D. = 6.73, range 27.0 to 53.0). The uvular angle observed in the Lengua. Indians is higher than that recorded for the Bushmen (males: x = 53.66, S.D. = 4.16, range = 45.0 to 67.0; females: x = 50.27, S.D. = 6.36, range 40.0 to 63.6). Discussion
The Lengua Indians have Mongoloid facial features, as described by Bjork,‘“, I4 and this factor may influence the anatomic shape of their nasopharyngeal regions. From the lengths of the posterior cranial bases, it would appear that there are also slight differences in skull size between the samples. The skeletal elements of the skull and cervical vertebrae control the size and shape of the soft-tissue pharynx, which is literally a group of muscular organs. Differences in the bony structures may thus markedly influence the soft-tissue dimensions as used by Schulhof. ’ In assessing the values recorded in Table I, morphologic differences between the races studied must be kept in mind. The Lengua Indians have relatively small mean anteroposterior dimensions (PNS-AA, Ba-S-PNS) of the bony nasopharyngeal areas, while the Bushmen have comparatively high values for these parameters (Table I). The converse holds true for the vertical measurements (SOS-IN, S-Ba-PNS). The primitive races have relatively high values for the dimensions D-AD1 : PNS and D-AD2:PNS when compared to the sample of Caucasoids.’ These measurements again show that the Bushmen have deep nasopharyngeal air spaces, while the Lengua Indians
6
Preston
Am. J. Orthud. December 1979
have relatively less anteroposterior development for this region. The Lengua Indians, however, compensate by having greater vertical growth in this area. The effective airway spaces are thus greater in the two preliterate tribes than in the Caucasoid’ sample. The Caucasoids’. ’ who constitute the control in this study were selected from an age group in which the adenoids are at their maximal size. The nasopharynx provides space on its posterior wall for lymphoid tissue which often hypertrophies during childhood and which is then recognized as the “adenoids, ‘~~3 23 Anatomically, the pharyngeal tonsils or adenoids which appear at about the sixth month of fetal life as a subepithelial infiltration of lymphocytes lie on the roof and upper posterior wall of the nasopharynx.24, 25 In the adenoid tissue the lymphoid nodules are directly under the epithelium and, in view of their extensively cryptic structure, offer a wide area of contact between these two structures. The adenoidal lymphoid tissue is thought to play a major role in antibody production since its nodules are separated from the oral cavity by only a layer of epithelium and it is thus constantly exposed to bacterial contact. 23 The adenoids follow a lymphoid tissue growth pattern and reach nearly 200 percent of adult size at the age of 12 years. Their size then undergoes a sharp decrease until it is reduced to 100 percent attainment at the age of approximately 20 years.‘6 The samples of preliterate peoples were selected from Lengua Indian adults who had a maximum age of 55 years (male: X = 35 years; female: x = 39 years) and from adult Bushmen with full permanent dentitions. It may thus be expected, on the basis of age, that the amounts of lymphoid tissue in the Caucasoids and preliterate tribes could be different. The airway percentage may be expressed as the percentage of nasopharynx occupied by adenoid tissue.“3 The technique suggested by Handelman requires somewhat sophisticated mathematical analysis. For the present study I have used the technique suggested by Ricketts2 to determine the extent of soft-tissue intrusion into the nasopharynx. The amount of adenoid tissue is represented by a percentage of tissue that is covered along the SOS-IN line. In the Caucasoid sample of Rickett? the average age was 12% years. In these children the maximum adenoid tissue was 92 percent of the SOS-IN dimension, while the low was only 19 percent. The mean of this measurement was recorded as 56 percent. In the Bushman male the mean percentage is 35.55 percent (S .D. = 13.11, range = 12.5 to 71. II), while in female the percentage for this parameter is slightly higher (x = 37.38, S.D. = 13.25, range = 14.28 to 77.27). In the Lengua Indians the percentages of soft-tissue encroachment on the airway space are considerably smaller (male: X = 31.21, S.D. = 10.58, range = 17.3 to 68.0; female: x = 25.84, S.D. = 9.24, range = 14.5 to 42.2). The findings indicate that the Bushmen and the Lengua Indians have less adenoid tissue than do the Caucasoid samples.” 2 The results also appear to support the contention that preliterate peoples are better equipped for nasal breathing.7. ’ It may be noted that Angle, 27in 1907, featured the faces of two adult male Plains Indians. He remarked on the balance in their faces and especially of their mouths, which are in perfect balance with the rest of their features. Angle27 was greatly influenced by George Catlin” who, in 1861, “thundered” against mouth breathing.‘$ Catlinz8 believed that mouth breathing resulted in a large number of psychosocial and dentofacial problems. None of the preliterate subjects had skeletal malocclusions which could be classified as being either Class II or Class III. I6 It is also recorded that none of them were mouth breathers or were at the time suffering from any allergic manifestations.
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It is difficult to draw any definite conclusions from this study, but the indications are that there is less soft-tissue encroachment into the nasopharynges of the two preliterate peoples studied than in the Caucasoid controls. As the Bushman and Lengua samples are not comparable to the Caucasoid samples with respect to age, further studies are required to determine normal values for younger groups of preliterates in order to make comparisons more meaningful. I would like to express my sincere appreciation to the Paraguayan Government, the South West African Administration, and the South African Medical Research Council for the assistance they gave me in undertaking this project. I would also like to thank the following people for their valued assistance: Professor A. Jacobson, Dr. V. Boettner, Dr. C. Perreira, and Professor J. F. van Reenen. Also, I wish to thank Mrs. R. Milstein for typing the manuscript. REFERENCES 1. Schulhof, R. .I.: Consideration of airway in orthodontics, J. Clin. Orthod. 12: 440-444, 1978. 2. Ricketts, R. M.: The cranial base and soft structures in cleft palate speech and breathing, Plast. Reconstr. Surg. 14: 47-61, 1954. 3. Ricketts, R. M.: Respiratory obstruction syndrome, AIM. J. ORTHOD. 54: 495-507, 1968. 4. Linder-Aronson, S.: Adenoids: Their effects on mode of breathing and airflow and their relationship to characteristics of facial skeleton and the dentition, Acta Otolaryngol. Suppl. 265: 1, 1970. 5. Krogman, W. M.: Forty years of growth research and orthodontics, AM. J. ORTHOD. 63: 357, 1973. 6. Marks, M. B.: Allergy in relation to orofacial dental deformities in children; a review, J. Allergy 36: 293-302, 1965. 7. Balyeat and Bowen: Quoted by Ricketts, R. M.: Respiratory obstruction syndrome, AM. J. ORTHOD. 54: 495-507, 1968. 8. Buettner-Janusch, J.: Physical anthropology: A perspective, New York, 1973, John Wiley & Sons, Inc., p. 98. 9. Sincock: Quoted by Ricketts, R. M.: Respiratory obstruction syndrome, AM. J. ORTHOD. 54: 495-507, 1968.
10. Metraux, A.: Ethnography of the Chaco. In Steward, J. H. (editor): Handbook of South American Indians, Bureau of American Ethnology, Bull. No. 143, Washington, D. C., (RepublishedNew York, 1963, Cooper Square) 1946, Smithsonian Institution, pp. 197.370. 11. Grubb, W. B.: An unknown people in an unknown land: An account of the life and customs of the Lengua Indians of the Paraguayan Chaco, with adventures and experiences during twenty years’ pioneering and exploration amongst them, ed. 2, London, 1911, Seely, Service & Co., Ltd. 12. Brown, S. M., Gajdusek, D. C., Leyshon, W. C., Steinberg, A. G., Brown, K. S., and Curtain, C. C.: Genetic studies in Paraguay: Blood group, red cell and serum genetic patterns of the Guayaki and Ayore Indians, Mennonite settlers and seven other Indian tribes of the Paraguayan Chaco, Am. J. Phys. Anthropol. 41: 317-344, 1974. 13. BjGrk. A.: The face in profile, Sven. Tandl%k. Tidskr. (Suppl). 40: 5B, 1947. 14. Bjb;rk, A.: Some biological aspects of prognathism and occlusion of the teeth, Acta Odontol. Stand. 9: l-40, 1950. 15. Tobias, P. V. (editor): The Bushmen, San Hunters and Herders of Southern Africa, Capetown and Pretoria, 1978, Human & Rosseau, pp. 1 l-12. 16. Jacobson, A., Preston, C. B., Boettner, V. A., and Pereira, C. B.: The craniofacial pattern of the Lengua Indians of Paraguay, Am. J. Phys. Anthropol. 47: 467-472, 1977. 17. Lavelle, C. L. B.: An analysis of the craniofacial complex in different occlusal categories, An. J. ORTHOD. 7: 574..582, 1977. 18. de Villiers, H.: The skull of the South African Negro: A biometrical and morphological study, Johannesburg, 1968, Witwatersrand University Press, 19. Singer, R.: The biology of the San. In Tobias, P. V. (editor): The Bushmen, 1978, Human & Rousseau Publishers, pp. 115-129. 20. Brodie, A. G.: On the growth pattern of the human head from the third month to the eighth year of life, Am. J. Anat. 68: 209, 1941.
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King, E. W.: A roentgenographic study of pbaryngeal growth, Angle Orthod. 22: 23-37, 1952. Rosenberger, A. C.: Growth and development of the naso-respiratory area in childhood, Ann. Otol. Rhinol. Laryngol. 43: 495-513, 1934. Handelman, C. S., and Osborne, G.: Growth of the nasopharynx and adenoid development from one to eighteen years, Angle Orthod. 46: 243-259, 1976. Van Alyea, 0. E.: The embryology of the ear, nose and throat, section on instruction, 1949. American Academy of Ophthalmology and Otolaryngology. Waldapfel, R.: The tonsil problem in the adult. Eye, Ear, Nose Throat Month. 30: 27, 1954. Baer, M. J.: Growth and maturation; an introduction to physical development, Cambridge, Mass., 1973, Howard A. Doyle, p. 7. Angle. E. H.: Treatment of malocclusion of the teeth, ed. 7, Philadelphia, 1907, S. S. White Dental Mfg. Co. Catlin, G.: The breath of life: Or mal-respiration and its effects upon the enjoyments and life of man, New York, 1861, John Wiley & Sons, Inc. (Reprinted in 1925 with preface by E. H. Angle.) Krogman, W. M.: The creativity of Edward H. Angle: Retrospect and prospect, Angle Orthod. 46: 209-218, 1976.
THE JOURNAL
50 YEARS
AGO
in twenty-five years years of infantile struggling, the orthodontic profession, as a whole, has yet been unable to throw off its swaddling clothes and in its efforts to overcome its limitations and failures grasps at fanciful theories and methods without any apparent analytic reasoning, and may be likened unto the proverbial drowning man and the straw. ‘Tis true we have striven for and almost reached mechanical perfection but with no apparent progress as to proved causative factors, no diminution of time in treatment or appreciable lowering in the percentage of failures, a sad commentary. (Robert Dunn: The international Journal of Orthodontia, Oral Surgery and Radiology, July, 1929.)