- Email: [email protected]
Evaluation of oral function of the orthodontic patient
Evaluation of oral function of the orthodontic patient James Bethesda,
F. Bosma,
M.D.*
Md.
T
his tribute to Dr. H. C. Pollock is offered by one whose work is related to orthodontics. It offers my conceptual framework of studies of function and form of the child’s mouth. The perspcctivc is that of postnatal development of the pharynx and the mouth, In early infancy, these two organs perform as a closely knit composite. In this integration the pharynx, the more primitive element, is commonly dominant. I’ostnatally, the mouth acquires autonomy and differentially progresses to the rnost complex and heterogeneous actions effected by our motor mechanisms. These are the results of developmental encephalization, whereby the successively acquired representations of the mouth are integrated with the maturing environmental orientation, intelligence, and emotions of the organism. In recent years, we have increasingly recognized the role of the mouth’s sensory systerns in its neurologic development. This role includes the immediate guidance of actions of the mouth by proprioception from the musculature of the mandible, hyoid bone, and tongue and from the teeth and oral surfaces. It also includes the more elegant exteroceptions from the oral surfaces which penetrate directly or by neuronal relay through the branchial nuclei to representations in the thalamus and cerebrum and which implement our most sophisticated surface touch perception, sensorimotor manipulations, and chemosensory detection and discrimination. These cxteroccptive afferents and the motor functions which they elicit and guide are the basis of common variations in function and associated variations in the form of the human mouth. Accordingly, developmental stomatology is concerned with both the anatomically growing mouth and with t,he oral representations in the maturing encephalon which determine the mouth’s sensorimotor functions. The two major functions of the newborn infant,% mouth are those of positional *Chief, Research,
578
Oral and National
Phargngeal Institutes
of
Development Health.
Section,
National
Institute
of
Dental
Oral function
of orthodontic
patient
579
stabilization and feeding. Positional stabilixation of the dorsal portion of the mouth is a function shared with the pharynx and is also a part of pharyngeal participation in respiration. Throughout postnatal life, the column arrangement of tongue, hyoid, and larynx is held forward, maintaining patency of the airway in the pharynx and the laryngeal vestibule. This column is also held lipward, with the tongue in approximation to the palate, so that the airway is in continuity with the nose, rather than the mouth. The soft palate is active in this approximation, separating the mouth from the pharynx (Fig. 1, A). With the postnatal elongation of the vertical array of the mandible, hyoid, and larynx, the composition of the anterior wall of the pharynx is changed by the appearance of the tongue between the palate and the epiglottis (Fig. 1, B) . The mandible is a motor reference for this position of the tongue-hyoid-larynx column ; accordingly, we evaluate the positional stability of the column by passively lowering the mandible and attempting manually to displace the hyoid and then the tongue backward and/or downward. In the normal subject, this action is actively resisted. Another maneuver of evaluation of the tongue-hyoid-larynx column stability in relation to the pharyngeal airway is that of passive anteflexion of the head on the neck. In the normal subject, the hyoid and tongue are actively moved toward mandibular symphysis during this maneuver, but in impairment of this function the tongue and epiglottis protrude into the pharyngeal airway and may occlude it. The stability of this column on a longer calendar of observation is indicated by consistency of the anteroposterior diameter of the air-outlined mesopharynx; after surgical shortening of the mandible in prognathic adults, the tongue mass is not displaced backward with the body of the mandible but, with the hyoid, is displaced d0wnward.l
B
A
Fig. 1. Schema of spatial orientation muscles in the newborn infant (A) and
of mouth in the adult
and (B).
pharynx
and
of
hyoid
suspensory
580
Bosrna
Am.
J. Orthodontics June1969
This mechanism of stability of the tongue-hyoid-larynx column is critically impaired in the syndrome of Robin in which ptosis and retrodisplacement of the column and rctrusion and hinge-patt.erned motions of the mandible arc associated with hypoplasia or cleft of the dorsal portion of the palate.’ This positional stabilization about the pharyngeal airway is a primitive mechanism, below our subjective awareness. It is determinant of spatial relations of the tongue, hyoid, and mandible to each other and to other cervical and facial structures.” The anterior part of the mouth undergoes extensive and conspicuous postnatal changes in spatial arrangement and in posit.ion. In the infant at rest, the tongue generally approximates the hard palate. During or temporally adjacent to suckling, the tongue tip commonly approximates the lower lip. In minor motions and in the stereotyped suckle maneuvers the anterior part of tongue, the lower lip, and the mandible move in synergy as a composite motor organ.” The lips may be pursed in closure about a nipple or similar stimulus, but otherwise the upper and lower lips are not consistently in contact. With postnatal expansion of the facial skeleton and oral cavity, and wit,h the descent of the tongue-hyoid-larynx column, a “masticatory space” appears in the front of the mouth. More significantly, the tongue, lips, and mandible achieve independent function. The mandible becomes a stable spar in the motor system of upright posture and also, with its newly acquired periodontal sensors, performs as the primary effector in biting and chewing. The lips acquire a gate function. The expanded oral cavity is thus enclosed by the dental array and the consistently apposed lips. However, the most striking developmental adaptation of the human mouth is that of the mobile anterior portion of the tongue within the expanding oral cavity. This is analogous to the developmental enlargement of the upper pharynx and the acquisition of matching mobility of the soft palate. The postnatal sequence of development of the feeding a&o?@ are somewhat analogous to those of positional stabilization. During infant swallow, the anteroposterior position of the tongue-hyoid-larynx column approximates its position during tidal respiration, and the constrictor walls converge about the column in that position.” The tongue and hyoid then move forward in the final phase of swallowing. As the tongue-hyoid-larynx column descends and elongates, swallowing is changed in pattern of displacements; the initial and principal motions are of elevation and shortening of the column and of the constrictor walls of the pharynx. The hyoid then moves forward as the body of the tongue rolls backward to approximate the slightly moving dorsal pharyngeal wall5 The maturation of feeding actions of the mouth is a process of acquisition of discriminate actions of the parts that had performed in simple synergy in the action of suckling. The lips prehend and manipulate in maneuvers which appear to integrate with their formation of the “labial gate.” The mandible differentially accomplishes biting and chewing. The tongue has multiple actions of prehension relevent to biting, to placing the bolus upon the molar table, and to gathering the bolus in preparation for swallowing. Its actions of sucking, of retention of bolus, and of convergence of bolus into pharynx resemble those of the infant. In our current perspective of development, this enumeration of achieved oral
Oml function
of odhodontic
patient
581
performances is quite misleading, for the essential development is of the central representations of the mouth. The prerequisite discrimination is in the information afferent from the mouth and from other sensory resources related to particular oral actions. In this perspective, the erupted teeth are significant as supplementary sensors as well as physical demarcations within the oral cavity and as instruments which facilitate biting and chewing. In this perspective, the continuing varied actions of the mouth are essential for maturation of its funetions, for most of the oral sensations are generated by its own motions. The acquisition of skills is the refinement of sensory guidance of the sa.me motor S,Wtern which generates the sensory experience constituting the background or subtrate of this development. The analysis and specification of these processes of neurologic development of oral function are a problematic task. The branchial representations in the brain stem have been the subject of exact neurophysiologic experimentation, from which the immediate proprioceptive guidance of trigeminal, facial, and hypoglossal motor function has been described,cp 7 and the internuncial mechanisms controlling the penetration of afferents through the trigeminal system have also been described.8, 9 Analogously, adequate descriptions are available of the infant oral functions of suckling49 lo, I1 and rooting,lO and of the mouth’s participation in infant crying.12 The current need is for experiments by which we may specify the sensory participations in the genesis of postnatal functional development. Methods should include imposition of stimuli, facilitation of autogenous stimulation, and temporary covering of selected receptor areas. Sensory elicitation or modulation may apply only to performances in their novel or nascent state. When they are stabilized in pattern, they may acquire the capacity for adequacy despite imposed variations in local sensation, like that which infant suckling and mature speech articulation13 seem to possess. The evaluation of novel sensorimotor function in subjects with mature oral awareness and cooperation is now well exemplified by studies of oral recognition of plastic forms, or “stereognosis.” There are a variety of routines of intermodal testing, comparing recognition by mouth with that by eye or hand,l”-16 and of intramodal testing, orally comparing a form with one previously in the n1outh.l’ Skills of tongue probing of graduated ridges or of patterned grooves in a plastic plate have been evaluated by Rutherford and McCall.l* The evaluation of novel or nascent oral functions of position, feeding, and speech requires the adaptation of methods of observation and of sensory cueing to infants and preschool children. These functions are well stabilized in the normal kindergarten or first-grade child. In other clinical fields, our experience with pathologic subjects allows strategic insights into basic mechanisms. Such has already been true of the development of oral function. The coincidentally developing encephalon and mouth are liable to several patterns of abnormality and impairment. The least disruption of central representation and of oral function is found in the circumstance of anomalies of oral form, as in cleft palate or in hypoplasia of the tongue.lg’ 2o If local sensation is adequate, these anomalous children commonly develop
582
Bosnta
Am.
J. Orthodontics Jtlne 1969
functionally adequate adaptive patterns of position, feeding, and speech articulation. IIowevcr, congenital deficiencies of oral tactile sensation were found to be associated in two children with general disruption of oral functions and with a pcrsistencc of distorted infantile oral feeding patterns and swallowing.“’ Their oral articulation of speech was minimal, and the few lip and tongue-tip speech gestures which one suhjcet learned at great effort by mirror practice wore not retained. In the evolution of oxgeriencc in our clinical study group, wc have now come to the LISC of sensory criteria as a basis of s,vndrome identification. I Jsing sens0r.y aberrations as criteria, IJcnkin, Ulristianscn, and Rosma2z have distinguished a syadromc group of five children with failure to recognize detected taste items (“recognition hypogcusia”) ! impairment of tliscrimination of twopoint touch, and patterned (“Type 2”) hyposmia. All of these children have facial hypoplasia, submucous cleft palate, general growt,li rctnrtlation, oral articulation disorders, and tongue-thrusting. These children demonstrate the juxtaposition of abnormalities of somatic form, of sensory and perceptual deficiency, and of distortions of coordination. Of these, the sensory ant1 percept,ual aberrations are the most specific. By such studies of clinical variations, we arc beginning to distinguish the multiple mechanisms of oral sensation and perception. Some specific variations, such as recognition of the taste of phenylthiocarbamate (PTC), are clearly within the norrnal variation of taste sensibility and are without recognizable associated abnormalities.‘3 Others, such as the impairments of taste detection in familial dysautonomia, arc concomitants of systemic disorders. Thcsc are gcnetically determined variations of oral sensation and perception. The individual is further defined by his own patterns of potential development of oral rcprescnt,ation under the influence of oral sensorimotor experience. These autogenous variations may be complicated again by nutritional disorders, such as the neuropathy found after kmashiorkor’” or in l~istidincmi:~.2” The development of oral representations in the encephalon is compounded further by intlividuality of oral involvement in life expcrienccs. Walter StanleyzG has shown that experimental variation in nutrient provision and in several variables of feeding circumstance are potent modifiers of puppy behavior; the puppies adapted rapidly and soon st,abilized in their newly learned patterns. The effectiveness of learning expcricnces involving feeding of human infants is familiar to mothers, whet,her t,hcy experience the completeness of social linkage by breast feeding or whether they mediate this by the nursing bottle. The infant and young child relate to mother and family in terms of their succcssion of feeding patterns. In a separate, later sequence, they select oral a.rticulations of speech to match that of their social ctnvironment. And, in still another parameter of expericncc, they utilize their mouth ilS a, site of affective csprcssion in digit-sucking, lip-suckin,, v or other oral rhythmic maneuvers. as we view the dcyelopment of oral function in the infant and child in this perspective of distinctive autonomous cxpacit,ics for oral experience compounded by his unique environmental experience, WC arc more aware that the essential
Oral function
of odhoclontic
patient
583
history of the mouth is recorded in its central representations. Its history is recorded more incidentally in the anatomic mouth and face, where the genetically determined elements of teeth, facial skeleton, and connective tissue have been continually modulated in position and form by the various sensorimotor functions of the mouth. REFERENCES
1. Takagi, Y., Gamble, J. W., Proffit, W. R., and Christiansen, R. L.: Postural change of the hyoid bone following osteotomy of the mandible, Oral Surg., Oral Med. & Oral Path. 23: 688-692, 1967. of upper respiratory and swallow 2. Bosmn, J. F., Truby, H. M., and Lind, J.: Distortions motions in infants having anomalies of the upper pharynx, Acta paediat. seandinav. Hupp. 163: 111-128, 1966. 3. Hosma, J. F.: Human infant oral function. In Symposium on oral sensation and perctption, Springfield, Ill., 1966, Charles C Thomas Publisher, chap. 4. 4. Ardran, G. M., Kemp, F. H., and Lind, J.: A cineradiographic study of bottle feeding, Brit. J. Radiol. 31: 11-22, 1958. 5. Atkinson, M., Kramer, P., Wyman, S. M., and Ingelfinger, F. J.: The dynamics of swallowing. I. Normal pharyngeal mechanisms, J. Clin. Invest. 36: 581-588, 1967. 6. Jerge, C. R.: The neural substratum of oral sensation. In Symposium I on oral sensation and perception, Springfield, Ill., 1966, Charles C Thomas Publisher, chap. 2. 7. Kawamura, Y.: A role of oral afferents for mandibular and lingual movements. In Symposium II on oral sensation and perception. (In press.) 8. King, R. B.: Interaction of peripheral inputs within the trigeminnl complex. In Symposium II on oral sensation and perception. (In press.) 9. Dubner, R.: Peripheral and central input to the main sensory trigeminal nucleus of the cat. In Symposium II on oral sensation and perception. (In press.) 10. Pieper, A.: Die Eigeuart dcr kindlichen Hirntatigkeit, ed. 2, Leipzig, 1956, Georg Thieme Verlag. 11. Kron, R. E.: Studies of sucking behavior in the human newborn: The predictive value of measures of earliest oral behavior. In Symposium II on oral sensation and perception. (In press.) 12. Bosma, J. F., Truby, H. M., and Lind, J.: Cry motion of the newborn infant, Acta paediat. scandinar. Supp. 163: 61-92, 1965. 13. Ringel, R. L., and Steer, M. D.: Some effects of tactile and auditory alterations on spceeh output, J. Speech & Hearing Res. 6: 369-378, 1963. 14. McDonald, E. T., and Aungst, L. F.: An abbreviated test of oral stereognosis. In Symposium II on oral sensation and perception. (In press.) 15. Arndt, W. B., Elbert, M., and Shelton, R,. L.: Standardization of a test of oral stereognosis. In Symposium II on oral sensation and perception. (In press.) 16. Weinberg, B., Lyons, M. J., and Liss, G. M.: Studies of oral, manual, and visual form identification in children and adults. In Symposium II on oral sensation and perception. (In press.) 17. Ringel, R. L., Burk, K. W., and Scott, C. M.: Tactile perception: Form discrimination in t,hc mouth, Brit. J. Dis. Comm. 3: 150.155, 1968. 18. Rutherford, D., and McCall, G.: Testing oral sensation and perception in persons with dysarthris. In Symposium I on oral sensation and perception, Springfield, Ill., 1966, Charles C Thomas Publisher, chap. 10. 19. Salzmann, J. A., and Seide, L. J.: Malocclusion with extreme mieroglossia, A&l. J. ORTHODONTICS 48: 11, 84%857,1962. 20. Weinberg, B., Christensen, R., Logan, W., Bosma, J. F., and Wornall, A. : severe ]lypoplasia of the tongue, J. Speech & Hearing Disorders. (In press.) 21. Bosma, J. F., Grossman, R. C., and Kavanagh, J. F.: A syndrome of impairment of oral
584
22.
23.
24.
25.
26.
Bosrna
Am.
J. Odhodontics June 1969
percehtion. In Symposium I on oral sensation and perception, Springfield, JII., 1966, Charles C Thomas Publisher, chap. 18. Hcnkin, R. I., Christiansen, R. L., and Bosma, J. F.: Facial llypoplasia growth retardation, impairment of oral sensation and perception and hyposmia. In symposium II on oral sensation and perception. (In press.) Chung, (!. S., Witkop, C. J., Wolf, R. O., and Brown, Ii. 8.: Dental caricls in relation to PTC taste sensitivity, secretor status and salivary thiocyanate level, Arch. Oral Biol. 10: 645653, 1965. Witkop, C. J., Baldizon, C. G., Castro, O., and Umnna, R.: Auditory memory span and oral stcreognosis in children recovered from kmashiorkor. In Symposium TT on oral sensation and perception. (In press.) Witkop, C. J., and Henry, F.: Sjggren-Larsson syndrome and histidinemia: Hweditary biochemical diseases with defects of speech and oral functions, J. Speech & Hearing Tjisorders 28: 109-123, 1963. Stanley, XV’.: Variables controlling sucking behavior in dogs. In Symposium I [ on oral sensation and perception. (Tn press.)
F. Bosma,
M.D.*
Md.
T
his tribute to Dr. H. C. Pollock is offered by one whose work is related to orthodontics. It offers my conceptual framework of studies of function and form of the child’s mouth. The perspcctivc is that of postnatal development of the pharynx and the mouth, In early infancy, these two organs perform as a closely knit composite. In this integration the pharynx, the more primitive element, is commonly dominant. I’ostnatally, the mouth acquires autonomy and differentially progresses to the rnost complex and heterogeneous actions effected by our motor mechanisms. These are the results of developmental encephalization, whereby the successively acquired representations of the mouth are integrated with the maturing environmental orientation, intelligence, and emotions of the organism. In recent years, we have increasingly recognized the role of the mouth’s sensory systerns in its neurologic development. This role includes the immediate guidance of actions of the mouth by proprioception from the musculature of the mandible, hyoid bone, and tongue and from the teeth and oral surfaces. It also includes the more elegant exteroceptions from the oral surfaces which penetrate directly or by neuronal relay through the branchial nuclei to representations in the thalamus and cerebrum and which implement our most sophisticated surface touch perception, sensorimotor manipulations, and chemosensory detection and discrimination. These cxteroccptive afferents and the motor functions which they elicit and guide are the basis of common variations in function and associated variations in the form of the human mouth. Accordingly, developmental stomatology is concerned with both the anatomically growing mouth and with t,he oral representations in the maturing encephalon which determine the mouth’s sensorimotor functions. The two major functions of the newborn infant,% mouth are those of positional *Chief, Research,
578
Oral and National
Phargngeal Institutes
of
Development Health.
Section,
National
Institute
of
Dental
Oral function
of orthodontic
patient
579
stabilization and feeding. Positional stabilixation of the dorsal portion of the mouth is a function shared with the pharynx and is also a part of pharyngeal participation in respiration. Throughout postnatal life, the column arrangement of tongue, hyoid, and larynx is held forward, maintaining patency of the airway in the pharynx and the laryngeal vestibule. This column is also held lipward, with the tongue in approximation to the palate, so that the airway is in continuity with the nose, rather than the mouth. The soft palate is active in this approximation, separating the mouth from the pharynx (Fig. 1, A). With the postnatal elongation of the vertical array of the mandible, hyoid, and larynx, the composition of the anterior wall of the pharynx is changed by the appearance of the tongue between the palate and the epiglottis (Fig. 1, B) . The mandible is a motor reference for this position of the tongue-hyoid-larynx column ; accordingly, we evaluate the positional stability of the column by passively lowering the mandible and attempting manually to displace the hyoid and then the tongue backward and/or downward. In the normal subject, this action is actively resisted. Another maneuver of evaluation of the tongue-hyoid-larynx column stability in relation to the pharyngeal airway is that of passive anteflexion of the head on the neck. In the normal subject, the hyoid and tongue are actively moved toward mandibular symphysis during this maneuver, but in impairment of this function the tongue and epiglottis protrude into the pharyngeal airway and may occlude it. The stability of this column on a longer calendar of observation is indicated by consistency of the anteroposterior diameter of the air-outlined mesopharynx; after surgical shortening of the mandible in prognathic adults, the tongue mass is not displaced backward with the body of the mandible but, with the hyoid, is displaced d0wnward.l
B
A
Fig. 1. Schema of spatial orientation muscles in the newborn infant (A) and
of mouth in the adult
and (B).
pharynx
and
of
hyoid
suspensory
580
Bosrna
Am.
J. Orthodontics June1969
This mechanism of stability of the tongue-hyoid-larynx column is critically impaired in the syndrome of Robin in which ptosis and retrodisplacement of the column and rctrusion and hinge-patt.erned motions of the mandible arc associated with hypoplasia or cleft of the dorsal portion of the palate.’ This positional stabilization about the pharyngeal airway is a primitive mechanism, below our subjective awareness. It is determinant of spatial relations of the tongue, hyoid, and mandible to each other and to other cervical and facial structures.” The anterior part of the mouth undergoes extensive and conspicuous postnatal changes in spatial arrangement and in posit.ion. In the infant at rest, the tongue generally approximates the hard palate. During or temporally adjacent to suckling, the tongue tip commonly approximates the lower lip. In minor motions and in the stereotyped suckle maneuvers the anterior part of tongue, the lower lip, and the mandible move in synergy as a composite motor organ.” The lips may be pursed in closure about a nipple or similar stimulus, but otherwise the upper and lower lips are not consistently in contact. With postnatal expansion of the facial skeleton and oral cavity, and wit,h the descent of the tongue-hyoid-larynx column, a “masticatory space” appears in the front of the mouth. More significantly, the tongue, lips, and mandible achieve independent function. The mandible becomes a stable spar in the motor system of upright posture and also, with its newly acquired periodontal sensors, performs as the primary effector in biting and chewing. The lips acquire a gate function. The expanded oral cavity is thus enclosed by the dental array and the consistently apposed lips. However, the most striking developmental adaptation of the human mouth is that of the mobile anterior portion of the tongue within the expanding oral cavity. This is analogous to the developmental enlargement of the upper pharynx and the acquisition of matching mobility of the soft palate. The postnatal sequence of development of the feeding a&o?@ are somewhat analogous to those of positional stabilization. During infant swallow, the anteroposterior position of the tongue-hyoid-larynx column approximates its position during tidal respiration, and the constrictor walls converge about the column in that position.” The tongue and hyoid then move forward in the final phase of swallowing. As the tongue-hyoid-larynx column descends and elongates, swallowing is changed in pattern of displacements; the initial and principal motions are of elevation and shortening of the column and of the constrictor walls of the pharynx. The hyoid then moves forward as the body of the tongue rolls backward to approximate the slightly moving dorsal pharyngeal wall5 The maturation of feeding actions of the mouth is a process of acquisition of discriminate actions of the parts that had performed in simple synergy in the action of suckling. The lips prehend and manipulate in maneuvers which appear to integrate with their formation of the “labial gate.” The mandible differentially accomplishes biting and chewing. The tongue has multiple actions of prehension relevent to biting, to placing the bolus upon the molar table, and to gathering the bolus in preparation for swallowing. Its actions of sucking, of retention of bolus, and of convergence of bolus into pharynx resemble those of the infant. In our current perspective of development, this enumeration of achieved oral
Oml function
of odhodontic
patient
581
performances is quite misleading, for the essential development is of the central representations of the mouth. The prerequisite discrimination is in the information afferent from the mouth and from other sensory resources related to particular oral actions. In this perspective, the erupted teeth are significant as supplementary sensors as well as physical demarcations within the oral cavity and as instruments which facilitate biting and chewing. In this perspective, the continuing varied actions of the mouth are essential for maturation of its funetions, for most of the oral sensations are generated by its own motions. The acquisition of skills is the refinement of sensory guidance of the sa.me motor S,Wtern which generates the sensory experience constituting the background or subtrate of this development. The analysis and specification of these processes of neurologic development of oral function are a problematic task. The branchial representations in the brain stem have been the subject of exact neurophysiologic experimentation, from which the immediate proprioceptive guidance of trigeminal, facial, and hypoglossal motor function has been described,cp 7 and the internuncial mechanisms controlling the penetration of afferents through the trigeminal system have also been described.8, 9 Analogously, adequate descriptions are available of the infant oral functions of suckling49 lo, I1 and rooting,lO and of the mouth’s participation in infant crying.12 The current need is for experiments by which we may specify the sensory participations in the genesis of postnatal functional development. Methods should include imposition of stimuli, facilitation of autogenous stimulation, and temporary covering of selected receptor areas. Sensory elicitation or modulation may apply only to performances in their novel or nascent state. When they are stabilized in pattern, they may acquire the capacity for adequacy despite imposed variations in local sensation, like that which infant suckling and mature speech articulation13 seem to possess. The evaluation of novel sensorimotor function in subjects with mature oral awareness and cooperation is now well exemplified by studies of oral recognition of plastic forms, or “stereognosis.” There are a variety of routines of intermodal testing, comparing recognition by mouth with that by eye or hand,l”-16 and of intramodal testing, orally comparing a form with one previously in the n1outh.l’ Skills of tongue probing of graduated ridges or of patterned grooves in a plastic plate have been evaluated by Rutherford and McCall.l* The evaluation of novel or nascent oral functions of position, feeding, and speech requires the adaptation of methods of observation and of sensory cueing to infants and preschool children. These functions are well stabilized in the normal kindergarten or first-grade child. In other clinical fields, our experience with pathologic subjects allows strategic insights into basic mechanisms. Such has already been true of the development of oral function. The coincidentally developing encephalon and mouth are liable to several patterns of abnormality and impairment. The least disruption of central representation and of oral function is found in the circumstance of anomalies of oral form, as in cleft palate or in hypoplasia of the tongue.lg’ 2o If local sensation is adequate, these anomalous children commonly develop
582
Bosnta
Am.
J. Orthodontics Jtlne 1969
functionally adequate adaptive patterns of position, feeding, and speech articulation. IIowevcr, congenital deficiencies of oral tactile sensation were found to be associated in two children with general disruption of oral functions and with a pcrsistencc of distorted infantile oral feeding patterns and swallowing.“’ Their oral articulation of speech was minimal, and the few lip and tongue-tip speech gestures which one suhjcet learned at great effort by mirror practice wore not retained. In the evolution of oxgeriencc in our clinical study group, wc have now come to the LISC of sensory criteria as a basis of s,vndrome identification. I Jsing sens0r.y aberrations as criteria, IJcnkin, Ulristianscn, and Rosma2z have distinguished a syadromc group of five children with failure to recognize detected taste items (“recognition hypogcusia”) ! impairment of tliscrimination of twopoint touch, and patterned (“Type 2”) hyposmia. All of these children have facial hypoplasia, submucous cleft palate, general growt,li rctnrtlation, oral articulation disorders, and tongue-thrusting. These children demonstrate the juxtaposition of abnormalities of somatic form, of sensory and perceptual deficiency, and of distortions of coordination. Of these, the sensory ant1 percept,ual aberrations are the most specific. By such studies of clinical variations, we arc beginning to distinguish the multiple mechanisms of oral sensation and perception. Some specific variations, such as recognition of the taste of phenylthiocarbamate (PTC), are clearly within the norrnal variation of taste sensibility and are without recognizable associated abnormalities.‘3 Others, such as the impairments of taste detection in familial dysautonomia, arc concomitants of systemic disorders. Thcsc are gcnetically determined variations of oral sensation and perception. The individual is further defined by his own patterns of potential development of oral rcprescnt,ation under the influence of oral sensorimotor experience. These autogenous variations may be complicated again by nutritional disorders, such as the neuropathy found after kmashiorkor’” or in l~istidincmi:~.2” The development of oral representations in the encephalon is compounded further by intlividuality of oral involvement in life expcrienccs. Walter StanleyzG has shown that experimental variation in nutrient provision and in several variables of feeding circumstance are potent modifiers of puppy behavior; the puppies adapted rapidly and soon st,abilized in their newly learned patterns. The effectiveness of learning expcricnces involving feeding of human infants is familiar to mothers, whet,her t,hcy experience the completeness of social linkage by breast feeding or whether they mediate this by the nursing bottle. The infant and young child relate to mother and family in terms of their succcssion of feeding patterns. In a separate, later sequence, they select oral a.rticulations of speech to match that of their social ctnvironment. And, in still another parameter of expericncc, they utilize their mouth ilS a, site of affective csprcssion in digit-sucking, lip-suckin,, v or other oral rhythmic maneuvers. as we view the dcyelopment of oral function in the infant and child in this perspective of distinctive autonomous cxpacit,ics for oral experience compounded by his unique environmental experience, WC arc more aware that the essential
Oral function
of odhoclontic
patient
583
history of the mouth is recorded in its central representations. Its history is recorded more incidentally in the anatomic mouth and face, where the genetically determined elements of teeth, facial skeleton, and connective tissue have been continually modulated in position and form by the various sensorimotor functions of the mouth. REFERENCES
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