i 1992 Europem Onhodomic Society
European Journal of Orlhodonlicj 14 (1992) 302-309
Malocclusion traits and articulatory components of speech Tellervo Laine Department of Orthodontics, University of Kuopio, Kuopio, Finland
Introduction
Although there have been many attempts to explain the relationship between speech and dental malocclusion the results are inconclusive for a variety of reasons. Previous studies have involved different populations, different linguistic areas and different methodologies for specifying articulation deficits and identifying malocclusions. Additionally, the relationship between speech and malocclusion is complicated by such factors as intelligence, hearing ability, speech standards of the environment and motivation (Rathbone, 1955). Higher frequencies of articulatory speech disorders have been reported to be associated with distal occlusion (Blyth, 1959; Subtelny et al., 1964), as well as the contrasting occlusal characteristic of mesial occlusion (Guay et al., 1978; Laine, 1987). Similarly, some report a higher frequency of misarticulations with open bite (Bernstein, 1954; Klechak et al, 1976; Guay et al., 1978), while others cite deep bite (Blyth, 1959; Lubit, 1967) as the source of most errors. The occlusal trait most often implicated in misarticulations is an anterior open bite. Researchers have consistently noted the relationship between an anterior open bite and sibilant disorders across languages (Ingervall and Sarnas, 1962; Klechak et al., 1976; Guay et al., 1978; Laine, 1987). One problem in studying the possible effects of malocclusions on speech sound production
is that the same individual may have a combination of several occlusal anomalies, with the number of different combinations being extensive across groups of subjects. This is also true for articulatory speech disorders, although the number of possible combinations clearly is smaller. Most studies focused only on certain misarticulations rather than all associated misarticulations. The aim of this study was to determine the effects of particular types of malocclusion including the effects of combinations of different occlusal anomalies on articulation. Subjects and methods
The subjects were 451 Finnish-speaking undergraduate students at the University of Jyvaskyla, 325 girls and 126 boys, corresponding to the sex ratio at the university. Mean and median age of the subjects was 23 years. Data collection has been described in detail in earlier publications (Laine and Hausen, 1982; Laine, 1984). Eleven per cent of the students had received orthodontic treatment and 6 per cent of them had undergone speech therapy. All had normal hearing. Occlusal and space anomalies using the method described by Bjork et al. (1964) with slight modifications were recorded by the same examiner. The prevalence of occlusal anomalies (Laine and Hausen, 1983), space anomalies
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SUMMARY The aim here was to determine the effects of particular types of malocclusion including the effects of combinations of different occlusal anomalies on speech articulation. Occlusal anomalies and articulatory speech disorders, a diagnosis based on errors in place of articulation, were determined for 451 students, mean age 23 years. The present results showed that risk ratios for producing consonants too far anteriorly was greater by 4.5 times for subjects with mesial occlusion, 3.7 times for those with mandibular overjet, 3.4 times for subjects with incisal open bite and 1.7 for those with lateral cross-bite compared to individuals without those occlusal anomalies. This study suggests that incisal open bite alone is rarely associated with articulatory speech disorders, but if present they tend to be mild. Incisal open bite combined with other occlusal anomalies, especially with mesial occlusion, is related to more severe misarticulations of consonants.
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MALOCCLUSION AND SPEECH SOUND PRODUCTION
(Laine and Hausen, 1985) and cumulative proportions of different types of malocclusions (Laine, 1984) were presented in previous reports. Table 1 shows the occurrence of occlusal anomalies as a single trait and that of combinations of different traits. In this sample of 451 students, 91 subjects (20 per cent) had neither occlusal nor space anomalies. 189 subjects had at least one occlusal anomaly, 30
different combinations being found. When space anomalies in addition to occlusal anomalies were considered, in the group of 360 students the total number of various combinations was 125. Articulatory speech disorders were diagnosed by two speech therapists independently. The diagnoses were identical in 85 per cent of the cases, indicating high interexaminer consistency.
Table 1 Distribution of subjects according to combination of different types of occlusal and space anomalies among Finnish students (/i = 451). %
n
I Occlusal anomalies (space anomalies included) Sagittal occlusal anomalies 37 DMO DMO+EMO 12 1 DMO + EMO + incisal deep bite DMO + EMO + incisal open bite 2 1 DMO + EMO + cross-bite I DMO + EMO + scissor bite DMO + incisal deep bite 3 DMO + incisal deep bite + scissor bite 2 DMO + cross-bite 6 DMO + cross-bite + scissor bite 1 DMO + scissor bite 3 7 MMO 1 MMO + MO + incisal open bite MMO + MO + incisal open bite + cross-bite 11 1 MMO + MO + cross-bite 1 MMO + cross-bite + scissor bite 1 EMO + scissor bite MO + incisal open bite 3 1 MO + incisal open bite + cross-bite Vertical occlusal anomalies Incisal deep bite Incisal deep bite + scissor bite Incisal open bite Incisal open bite + lateral open bite + cross-bite Incisal open bite + cross-bite Lateral open bite Lateral open bite + cross-bite Lateral open bite + scissor bite Transversal occlusal anomalies Cross-bite Cross-bite + scissor bite Scissor bite II
Space anomalies only Crowding and/or spacing
HI
No anomalies
8.2 2.7 0.2 0.4 0.2 0.2 0.7
Cumulative %
0.4 1.3 0.2 0.7 1.6 0.2
8.2 10.9 11 1 11.5 11.7 11.9 12.6 13.0 14.3 14.5 15.2 16.8 17.0
2.4 0.2 0.2 02 0.7 0.2
19.4 196 19.8 20.0 20.7 20.9
5 1 7
I.I 0.2 1.6
22.0 22.2 23.8
1 4 5 2 1
0.2 0.9 1.1 02 0.2
24.0 24.0 26 0 26.2 26.4
53
3 12
11.8 0.7 2.7
38.2 38.9 41.6
171
37.9
79.5
91
20.2
—
DMO = distal molar occlusion; MMO = mesial molar occlusion; EMO = extreme maxillary overjet; MO = mandibular overjet.
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Type of anomaly
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T. LAINE
All sounds found to be distorted in this sample were medioalveolar consonants: distortions of Is/-, /r/-, /I/-, /n/-, and /d/. Anterior variants were found in 28 per cent, posterior variants in 5 per cent, lateral variants as well as unclassified ones in 2 per cent of the students. Table 2 shows that in most cases the subjects had one articulatory speech disorder only, nine of them having distortions of at least two consonants, the greatest being one individual who had distortions of five different consonants. Eight persons had anterior variants of different consonants combined with each other and/or with unclassified variants. One individual had
a combination of a posterior and a lateral faulty variant. A log-linear function was fitted to analyse the relationship and interactions between different occlusal anomalies and articulatory speech disorders, considering the possible effects of previous dental treatment and speech therapy. Z-values of ^ 1.96 were considered statistically significant. Results Table 3 shows the statistically significant interactions regarding sagittal occlusal anomalies and different types of misarticulations. Mesial molar occlusion and mandibular overjet were related to consonants produced too far anteriorly (Z-values 3.28 and 2.60, respectively). Slightly less than one-quarter of the subjects without either of these anomalies had anterior variants while more than half of the subjects with these anomalies had consonants that were produced too far anteriorly. Risk ratios of having anterior variants was 4.5 for mesial occlusion and 3.7 for mandibular overjet, respectively. No statistically significant associations were found between distal molar occlusion or extreme maxillary overjet and any of the articulatory speech disorders. With regard to vertical occlusal anomalies, incisal open bite was clearly related to consonants that were produced too far anteriorly (Table 4). Less than one-quarter of the subjects
Table 2 Combinations of different types of articulatory disorders in speech according to errors of place of articulation among Finnishspeaking students (n = 451). Number of faulty variants of consonants
Number of subjects
Proportions of subjects (%)
Cumulative proportions of subjects (%)
AV PV LV UV AV + AV AV+AV+AV+AV+AV AV + UV AV + AV+UV PV+LV
104 16 10 5 1 2 4 I 1
23.1 3.5 2.2 1.1 0.2 0.4 0.9 02 0.2
23.1 26.6 28.8 29 9 30 1 30.5 31.4 31.6 31.8
AV = anterior variant; PV = posterior variant: LV = lateral variant; UV = unclassified variant.
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A detailed description of the method has been published (Laine et al., 1987). All acoustically distorted sounds were diagnosed according to type of sound disorder and faulty place of articulation. In this report, a diagnosis based on place of articulation was used. Placement was categorized as anterior, posterior, lateral or an unclassified variant of the sounds. An anterior variant indicates that the faulty sound has been produced anterior to the correct placement. Correspondingly, posterior variants have been produced posteriorly and lateral ones laterally when compared to the correct place of articulation of the specific sound. Unclassified variants are produced in a correct place, but are acoustically distorted in all phonetical contexts. Articulatory speech disorders were classified into grade 1 and grade 2, the latter indicating a need for treatment.
305
MALOCCLUSION AND SPEECH SOUND PRODUCTION
Table 3 Proportions of subjects with and without articulatory disorders in speech in subjects with sagittal occlusal anomalies (n = 451). Only statistically significant interactions are given. Occlusal anomalies Mesial molar occlusion
Mandibular overjet Yes
No
No
Yes
Articulatory disorders
n
No anterior variants
331
77
9
43
332
76
8
47
99
23
12
57
102
24
9
53
430
100
21
100
434
100
17
100
Anterior variants
n
%
n
%
3.28
Z-value*
%
2.60
* By a fitted log-linear function.
Table 4 Proportions of subjects with and without articulatory disorders in speech in subjects with vertical or transverse occlusal anomalies (n = 451). Only statistically significant interactions are given. Vertical anomalies
Transverse anomalies
Incisal open bite
Lateral cross-bite Yes
No
No
Yes
Articulatory disorders
n
No anterior variants
325
77
15
50
283
77
57
67
96
23
15
50
83
23
28
33
421
100
30
100
366
100
85
100
Anterior variants Total Z-value*
n
%
3.18
%
n
n
%
%
1 97
* By a fitted log-linear function
without open bite had this articulatory disorder while half of the subjects who had incisal open bite also had consonants produced too far anteriorly. With regard to lateral cross-bite the difference was smaller, 23 and 33 per cent, respectively. Risk ratios for producing consonants too far anteriorly were 3.4 times for subjects with open bite and 1.7 times for those with lateral cross-bite compared to individuals without those occlusal anomalies. Based on the results of log-linear function, subjects with mesial molar occlusion and incisal open bite were observed separately. Table 5 lists the subjects with mesial molar occlusion and
shows the combination of mesial occlusion with other occlusal anomalies, as well as the occurrence of misarticulations in those subjects. Twothirds of the subjects with mesial molar occlusion demonstrated articulatory speech disorders, primarily anterior variants that were grade 2. Two students who had several distorted sounds demonstrated a mesial molar occlusion and also an anterior open bite. In addition one also had a lateral cross-bite. Twenty out of thirty subjects with incisal open bite had articulatory speech disorders (Table 6). Six of them had an open bite as a single malocclusion trait, fourteen students had,
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Total
n
%
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T. LAINE
Table 5 Occurrence of combinations of misarticulations of consonants according to errors of place of articulation in subjects with mesial molar occlusion (n = 21) in young adults.
Table 6 Occurrence of combinations of misarticulations of consonants according to errors of place of articulation in subjects with incisal open bite (H = 30) in young adults.
Occlusal anomalies combined with mesial molar occlusion
Occlusal anomalies combined with incisal open bite
Grade 1 Grade 2
AV PV (n = 3) (n = 4) (n = 2) (n= 1) (n = 1)
MO + cross-bite (n = 1) Cross-bite + scissor bite (n= 1)
AV AV PV
— —
AV+AV+ AV + AV + AV AV + AV + UV AV
MO = manibular overjet; IOB = incisal open bite; AV = anterior vanant; PV = posterior variant; UV = unclassified variant.
in addition to open bite, at least one occlusal anomaly, most often mesial molar occlusion and/or lateral cross-bite. Eight individuals had one mild anterior, posterior or unclassified misarticulation of a consonant. Twelve subjects had more severe, mainly anterior variants, one of them having a combination of five anterior variants and one individual revealing a combination of one unclassified and two anterior variants. Discussion Articulatory speech disorders while not the most severe type, represent 50-60 per cent of all speech disorders (Van Riper, 1978), thus being relatively important in terms of channelling resources for speech therapy. There are a variety of methods for diagnosing articulation disorders in speech. In the present study, both the traditional classification, based on acoustical perception of different sounds (Van Riper, 1978), and spatial classification, describing movements of the tongue during speech sound production, were used. From a functional point of view, diagnosing on the basis of place of articulation seems to be more relevant. Although there are some who suggest that articulation disorders are psychologically based,
None(n=l) None(n = 2) None(n = 2) None(n=l) None(n=l) MMO + MO + cross-bite (n = 3) M MO + MO + cross-bite (" = 2) M MO + MO + cross-bite M MO + MO + cross-bite (n= 1) M MO + MO + cross-bite MMO+MO(n=l) MO + cross-bite (n= 1) MO(/7 = 3) Cross-bite (n = 3) Cross-bite [n= 1) DMO+EMO (n=I) DMO + EMO (/?=1) Cross-bite + lateral open bite
Misarticulation Grade 1 Grade 2 AV — PV UV
— AV — —
AV
— AV
— PV
AV + AV + AV + AV + AV —
— — — — — UV —
AV + AV + UV LV — — AV AV — AV
MMO = mesial molar occlusion; MO = manibular overjet; DMO = distal molar occlusion; EMO = extreme maxillary overjet; AV = anterior variant; PV = posterior variant; UV = unclassified variant; LV = lateral variant.
learned phenomena, it is commonly acknowledged that articulation defects may have both organic and functional origin (Nichols, 1981). Speech movements consist of coarse and fine adjustments, a coarse movement preceding movements involving fine motor control. As the term articulation disorders or phonetic disorders describes an inability to produce certain sounds correctly due to difficulties with the motor production aspects of speech, phonological disorders, on the other hand, places speech sounds within the larger context of language. For individuals whose errors are primarily phonological in the presence of relatively normal motor-phonetic characteristics (Hardcastle et al., 1987), structural deviations are of no importance from an aetiological point of view. In this sample, all articulation disorders were distortions of different consonants, usually representing phonetic errors while phonological
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None (/i = 3) None(n = 3) None ( n - 1) MO + IOB + cross-bite MO + IOB + cross-bite MO + IOB + cross-bite MO + IOB + cross-bite MO + IOB + cross-bite
Misarticulation
MALOCCLUSION AND SPEECH SOUND PRODUCTION
It is obvious from the many reports in the literature that individuals can compensate for rather severe deviations of the orofacial structures and produce speech without distortions.
Although compensation is often mentioned in the literature (Rathbone, 1955; Benediktsson, 1958; Bankson and Byrne, 1962; Lubit, 1967; Bloomer, 1971; Van Riper, 1978; Lehtihalmes, 1984) little is known about the mechanisms involved in compensatory adjustments (Jensen, 1968; Weinberg, 1968; Subtelny et al., 1964, 1972; Kelso et al., 1984). Studies on function of the articulators for normal speech production (Lindblom, 1967; Lindblom and Sundberg, 1971; Subtelny et al., 1968, 1969, 1972; Niimi et al., 1982; Hirose, 1986) are supplemented by studies describing compensation under exceptional conditions, mainly in cleft palate patients (Subtelny et al., 1968, 1969; Warren, 1967, 1986; Dalston et al., 1988; Laine et al., 1988, 1989). There are also similar reports of an experimental nature (Lindblom et al., 1979; Gay et al., 1981; Warren et al., 1980, 1981, 1984; Putnam et al., 1986) demonstrating a better ability to compensate for induced malocclusions rather than natural ones. One interesting point relevant to the role of different types of malocclusion in articulatory speech disorders is that mesial molar occlusion with mandibular overjet occurs only rarely in young children while an incisal open bite and also lateral cross-bite frequently occur during speech development. Longitudinal studies to determine whether children with these occlusal anomalies and articulation disorders have the same faulty sounds at a later age or whether articulatory speech disorders appear later during development of the dentition, would clarify these issues. It is commonly hypothesized that misarticulations of especially /s/ and /r/ sounds are what Hardcastle et al. (1987) call 'residual speech errors', dating from the early stages of speech development. If this is true, any other malocclusion except those existing at the age of 2 to 4-5 years could not possibly have any effect on speech sound production. Finally, it is important to point out that the articulation of speech sounds is the last stage during the production of speech, preceded by respiration, phonation, and resonance. Recent studies have focused on control and regulation of breathing and aerodynamic variables during speech sound production (Smitheran and Hixon, 1981; Warren, 1982, 1986; Putnam et al., 1986; Warren el al., \9%9a,b). In addition, temporal responses of the vocal tract for normal speech utterances (Tuller and Kelso, 1984), as
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errors often comprise substitutions and omissions of different sounds. Previous studies concerning the relationship between malocclusions and speech disorders consist mainly of reports dealing with incisal open bite and distortions of the /s/ sound, although some studies considered tongue thrust swallowing as well. Undoubtedly, misarticulations of fricatives are the most common articulatory speech disorder in many languages and an association between incisal open bite and distortions of the unvoiced linguoalveolar /s/ sounds is the most common finding. Our results were parallel to previous findings. However, in the present sample individuals with mesial molar occlusion and anterior cross-bite showed a higher risk for articulatory speech disorders than those with incisal open bite. In addition, subjects with lateral cross-bite had a greater risk of articulation disorders than those without this occlusal anomaly. Differences between the results reported in this study and previous reports stem primarily from the fact that investigations focused on only one occlusal trait or one type of malocclusion rather than several occlusal traits. The only other study of mesial molar occlusion and articulation proficiency (Guay et al., 1978) reported findings that are consistent with the present results. Interestingly, in this and the Guay et al. study, mesial occlusions were mild in character. There are several explanations why individuals with a mesially located mandible and tongue might have difficulties in producing a correct unvoiced linguoalveolar /s/ sound. It is one of the most difficult sounds to produce, requiring precise placement and function of both the tip and the blade of the tongue as well as space enough anteriorly to the tip of the tongue in the most anterior part of the palate. Deviant structure or volume of the posterior part of the oropharynx may complicate adequate placement of the tongue. Indeed, subjects with Class III incisor relationship have been reported to have a different pattern of movement of the mandible (Howell, 1987) which may affect the close co-ordination of the lips, tongue, and mandible, required for accurate speech sound production (Lindblom and Sundberg, 1971).
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Address for correspondence
Tellervo Laine Department of Orthodontics Faculty of Dentistry University of Kuopio P.O. Box 1627
70211 Kuopio Finland Acknowledgements
The author wishes to thank Helena Rantala, B.A., and Arja-Liisa Linnasalo, M.A., Department of Special Education, University of Jyvaskyla, for diagnosing speech disorders. The study was financially supported by the Emil Aaltonen Foundation and by the Finnish Dental Society. References Bankson N W, Byrne M C 1962 The relationship between missing teeth and selected consonant sounds. Journal of Speech and Hearing Disorders 27: 341-348 Benediktsson E 1958 Variation in tongue and jaw position in 's' sound production in relation to front teeth occlusion. Acta Odontologica Scandinavica 15: 275-303 Bernstein M 1954 The relation of speech defects and malocclusion. American Journal of Orthodontics 40: 149-150
Bjork A, Krebs A, Solow B 1964 A method for epidemiologlcal registration of malocclusion. Acta Odontologica Scandinavica 22: 27-41 Bloomer H H 1971 Speech defects associated with dental abnormalities and malocclusions. In- Travis L E (ed ) Handbook of speech pathology. Prentice-Hall, Englewood Cliffs, NJ, pp. 608-652 Blyth P 1959 The relationship between speech, tongue behaviour, and occlusal abnormalities. Dental Practitioner 10: 11-20 Dalston R M, Warren D W, Morr K E, Smith L 1988 Intraoral pressure and its relationship to velopharyngeal inadequacy. Cleft Palate Journal 25: 210-219 Gay T, Lindblom B, Lubker J 1981 Production of biteblock vowels: Acoustic equivalence by selective compensation. Journal of Acoustical Society of America 69: 802-810 Guay A H, Maxwell D L, Beecher R 1978 A radiographic study of tongue posture at rest and during the phonation of /s/ in Class III malocclusion. Angle Orthodontist 48' 10-22 Hardcastle W J, Morgan Barry R A, Clark C J 1987 An instrumental phonetic study of lingual activity in articulation-disordered children. Journal of Speech and Hearing Research 30. 171-184 Hirose H 1986 Pathophysiology of motor speech disorders (dysarthria). Folia Phoniatrica 38. 61-88 Howell P G T 1987 The variation in the size and shape of the human speech pattern with incisor-tooth relation. Archives of Oral Biology 32: 587-592 Ingervall B, Sarnas K.-V 1962 Comparison of dentition in lispers and non-hspers. Odontologisk Revy 13: 344-354 Jensen R 1968 Anterior teeth relationship and speech. Acta Radiologica suppl 276: 1-69 Kelso J A S, Tuller B, Vatikiotis-Bateson E, Fowler C A 1984 Functionally specific articulatory cooperation following jaw perturbations during speech: Evidence for coordinative structures. Journal of Experimental Psychology: Human Perception and Performance 10: 812-832 Klechak T L, Bradley D P, Warren D W 1976 Anterior open bite and oral port constriction. Angle Orthodontist 46: 232-242 Laine T 1984 Morphology of the dentition in young adults. An epidemiological study on Finnish students. Proceedings of the Finnish Dental Society 80: suppl. IV, 1-42 Laine T 1987 Associations between articulatory disorders in speech and occlusal anomalies. European Journal of Orthodontics 9: 144-150 Laine T, Hausen H 1982 Cross-sectional study of orthodontic treatment and missing of permanent teeth in two birth cohorts of Finnish students according to sex. Community Dentistry and Oral Epidemiology 10: 209-213 Laine T. Hausen H 1983 Occlusal anomalies in Finnish students related to age, sex, absent permanent teeth and orthodontic treatment. European Journal of Orthodontics 5: 125-131 Laine T, Hausen H 1985 Space anomalies, missing permanent teeth and orthodontic treatment. Angle Orthodontist 55: 242-250 Laine T, Linnasalo A-L, Jaroma M 1987 Articulatory disorders in speech among Finnish speaking students
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well as to compensate structural deviations, have been studied (Warren et ai, 1989a). Studies on the linguistic aspects of speech, though extensive in number and of essential importance in the process of expressing thoughts as words, are outside the scope of this report. However, it should be realized that anatomical variation may play a minor role in this process. In summary, studies dealing with the developmental aspects of speech in relation to occlusion and 'compensatory' speech responses to the presence of structural deviations are clearly lacking, partly due to methodological difficulties. Regarding single traits of malocclusion, the present and earlier results of this sample of young adults indicate that individuals with mesial molar occlusion, mandibular overjet, incisal open bite and/or lateral cross-bite have a higher risk for articulatory speech disorders, especially consonants produced too far anteriorly. Incisal open bite alone is rarely associated with articulatory speech disorders, but if present they tend to be mild. Incisal open bite combined with other occlusal anomalies, especially with mesial occlusion, is related more often to more severe misarticulations.
T. LAINE
MALOCCLUSION AND SPEECH SOUND PRODUCTION according to age, sex and speech therapy Journal of Communication Disorders 20. 327-338 Laine T, Warren D W, Dalston R M, Hairfield W M, Morr K E 1988 Intraoral pressure, nasal pressure and airflow rate in cleft palate speech. Journal of Speech and Hearing Research 31: 432-437 Laine T, Warren D W, Dalston R M, Morr K E 1989 Effects of velar resistance on speech aerodynamics European Journal of Orthodontics II. 52-58 Lehtihalmes M 1984 Puheen fysiologian perusteista. In Narhi M, Johansson G (eds) Purentaelimen Fysiologia Turun Yliopiston Hammaslaaketieteen laitoksen off-set paino, Turku, pp. 201-210
Lindblom B E F, Sundberg E F 1971 Acoustical consequences of lip, tongue, jaw, and larynx movement. Journal of Acoustical Society of America 50: 1166-1179 Lindblom B, Lubker J, Gay T 1979 Formant frequencies of some fixed-mandible vowels and a model of speech motor programming by predective simulation Journal of Phonetics 7: 147-161 Lubit E C 1967 The relationship of malocclusion and faulty speech articulation Journal of Oral Medicine 22: 47-55 Nichols A C 1981 Articulation—Organic factors. In: Rieber R W (ed.) Communication Disorders. Plenum Press, New York and London, pp 3-19 Niimi S, Bell-Berti F, Harris K S 1982 Dynamic aspects of velopharyngeal closure. Folia Phoniatrica 34: 246—257 Putnam A H B, Shelton R L, Kastner C V 1986 Intraoral air pressure and oral air flow under different bleed and bite-block conditions. Journal of Speech and Hearing Research 29: 37-49 Rathbone J S 1955 Appraisal of speech defects in dental anomalies Angle Orthodontist 25' 42-48 Smitheran J R, Hixon T J 1981 A clinical method for estimating laryngeal airway resistance during vowel production. Journal of Speech and Hearing Disorders 46' 138-146 Subtelny J D, Mestre J C, Subtelny J D 1964 Comparative study of normal and defective articulation of/s/ as related to malocclusion and deglutition. Journal of Speech and Hearing Disorders 29- 269-285 Subtelny J D, McCormack R M, Subtelny J D, Worth J H, Cramer L M, Runyon J C, Rosenblum R M 1968
Synchronous recording of speech with associated physiological and pressure-flow dynamics: instrumentation and procedures. Cleft Palate Journal 5: 93-115 Subtelny J D, Kho G H, McCormack R M, Subtelny J D 1969 Multidimensional analysis of bilabial stop and nasal consonants—cineradiographic and pressure-flow analysis. Cleft Palate Journal 6- 263-289 Subtelny J D, Oya N, Subtelny J D 1972 Cineradiographic study of sibilants. Folia Phoniatnca 24: 30-50 Tuller B, Kelso J A S 1984 The timing of articulatory gestures- Evidence for relational invariants Journal of Acoustical Society of America 76: 1030-1036 Van Riper C 1978 Speech Correction Principles and methods. Prentice-Hall, Englewood Cliffs, NJ Warren D W 1967 Nasal emission of air and velopharyngeal function. Cleft Palate Journal 4- 148-156 Warren D W 1982 Aerodynamics of speech. In: Lass N J, McReynolds L V, Northern J L, Yoder D E, (eds) Speech, language and hearing. W B Saunders, Philadelphia, pp. 219-245 Warren D W 1986 Compensatory speech behaviors in individuals with cleft palate- A regulation/control phenomenon? Cleft Palate Journal 23 251-260 Warren D W, Nelson G R, Allen G 1980 Effects of increased vertical dimension on size of constriction port and fricative sound intelligibility Journal of Acoustical Society of America 67: 1828-1831 Warren D W, Hall D J, Davis J 1981 Oral port constriction and pressure-airflow relationships during sibilant productions. Folia Phoniatnca 33 380-393 Warren D W, Allen G. King H A 1984 Physiologic and perceptual effects of induced anterior open bite. Folia Phoniatnca 36. 164-173 Warren D W, Dalston R M, Morr K E, Hairfield W M, Smith L R 1989a The speech regulating system, temporal and aerodynamic responses to velopharyngeal inadequacy. Journal of Speech and Hearing Research 32. 566-575 Warren D W, Morr K E, Putnam Rochet A, Dalston R M 1989ft Respiratory response to a decrease in velopharyngeal resistance. Journal of Acoustical Society of Amenca 86 917-924 Weinberg B 1968 A cephalometric study of normal and defective /s/ articulation and variations in incisor dentition. Journal of Speech and Hearing Research 11: 288-300
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Lindblom B 1967 Vowel duration and a model of lip mandible coordination. Speech Transmission Laboratory' Quarterly Progress Status Report 4: 1-29
309
European Journal of Orlhodonlicj 14 (1992) 302-309
Malocclusion traits and articulatory components of speech Tellervo Laine Department of Orthodontics, University of Kuopio, Kuopio, Finland
Introduction
Although there have been many attempts to explain the relationship between speech and dental malocclusion the results are inconclusive for a variety of reasons. Previous studies have involved different populations, different linguistic areas and different methodologies for specifying articulation deficits and identifying malocclusions. Additionally, the relationship between speech and malocclusion is complicated by such factors as intelligence, hearing ability, speech standards of the environment and motivation (Rathbone, 1955). Higher frequencies of articulatory speech disorders have been reported to be associated with distal occlusion (Blyth, 1959; Subtelny et al., 1964), as well as the contrasting occlusal characteristic of mesial occlusion (Guay et al., 1978; Laine, 1987). Similarly, some report a higher frequency of misarticulations with open bite (Bernstein, 1954; Klechak et al, 1976; Guay et al., 1978), while others cite deep bite (Blyth, 1959; Lubit, 1967) as the source of most errors. The occlusal trait most often implicated in misarticulations is an anterior open bite. Researchers have consistently noted the relationship between an anterior open bite and sibilant disorders across languages (Ingervall and Sarnas, 1962; Klechak et al., 1976; Guay et al., 1978; Laine, 1987). One problem in studying the possible effects of malocclusions on speech sound production
is that the same individual may have a combination of several occlusal anomalies, with the number of different combinations being extensive across groups of subjects. This is also true for articulatory speech disorders, although the number of possible combinations clearly is smaller. Most studies focused only on certain misarticulations rather than all associated misarticulations. The aim of this study was to determine the effects of particular types of malocclusion including the effects of combinations of different occlusal anomalies on articulation. Subjects and methods
The subjects were 451 Finnish-speaking undergraduate students at the University of Jyvaskyla, 325 girls and 126 boys, corresponding to the sex ratio at the university. Mean and median age of the subjects was 23 years. Data collection has been described in detail in earlier publications (Laine and Hausen, 1982; Laine, 1984). Eleven per cent of the students had received orthodontic treatment and 6 per cent of them had undergone speech therapy. All had normal hearing. Occlusal and space anomalies using the method described by Bjork et al. (1964) with slight modifications were recorded by the same examiner. The prevalence of occlusal anomalies (Laine and Hausen, 1983), space anomalies
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SUMMARY The aim here was to determine the effects of particular types of malocclusion including the effects of combinations of different occlusal anomalies on speech articulation. Occlusal anomalies and articulatory speech disorders, a diagnosis based on errors in place of articulation, were determined for 451 students, mean age 23 years. The present results showed that risk ratios for producing consonants too far anteriorly was greater by 4.5 times for subjects with mesial occlusion, 3.7 times for those with mandibular overjet, 3.4 times for subjects with incisal open bite and 1.7 for those with lateral cross-bite compared to individuals without those occlusal anomalies. This study suggests that incisal open bite alone is rarely associated with articulatory speech disorders, but if present they tend to be mild. Incisal open bite combined with other occlusal anomalies, especially with mesial occlusion, is related to more severe misarticulations of consonants.
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MALOCCLUSION AND SPEECH SOUND PRODUCTION
(Laine and Hausen, 1985) and cumulative proportions of different types of malocclusions (Laine, 1984) were presented in previous reports. Table 1 shows the occurrence of occlusal anomalies as a single trait and that of combinations of different traits. In this sample of 451 students, 91 subjects (20 per cent) had neither occlusal nor space anomalies. 189 subjects had at least one occlusal anomaly, 30
different combinations being found. When space anomalies in addition to occlusal anomalies were considered, in the group of 360 students the total number of various combinations was 125. Articulatory speech disorders were diagnosed by two speech therapists independently. The diagnoses were identical in 85 per cent of the cases, indicating high interexaminer consistency.
Table 1 Distribution of subjects according to combination of different types of occlusal and space anomalies among Finnish students (/i = 451). %
n
I Occlusal anomalies (space anomalies included) Sagittal occlusal anomalies 37 DMO DMO+EMO 12 1 DMO + EMO + incisal deep bite DMO + EMO + incisal open bite 2 1 DMO + EMO + cross-bite I DMO + EMO + scissor bite DMO + incisal deep bite 3 DMO + incisal deep bite + scissor bite 2 DMO + cross-bite 6 DMO + cross-bite + scissor bite 1 DMO + scissor bite 3 7 MMO 1 MMO + MO + incisal open bite MMO + MO + incisal open bite + cross-bite 11 1 MMO + MO + cross-bite 1 MMO + cross-bite + scissor bite 1 EMO + scissor bite MO + incisal open bite 3 1 MO + incisal open bite + cross-bite Vertical occlusal anomalies Incisal deep bite Incisal deep bite + scissor bite Incisal open bite Incisal open bite + lateral open bite + cross-bite Incisal open bite + cross-bite Lateral open bite Lateral open bite + cross-bite Lateral open bite + scissor bite Transversal occlusal anomalies Cross-bite Cross-bite + scissor bite Scissor bite II
Space anomalies only Crowding and/or spacing
HI
No anomalies
8.2 2.7 0.2 0.4 0.2 0.2 0.7
Cumulative %
0.4 1.3 0.2 0.7 1.6 0.2
8.2 10.9 11 1 11.5 11.7 11.9 12.6 13.0 14.3 14.5 15.2 16.8 17.0
2.4 0.2 0.2 02 0.7 0.2
19.4 196 19.8 20.0 20.7 20.9
5 1 7
I.I 0.2 1.6
22.0 22.2 23.8
1 4 5 2 1
0.2 0.9 1.1 02 0.2
24.0 24.0 26 0 26.2 26.4
53
3 12
11.8 0.7 2.7
38.2 38.9 41.6
171
37.9
79.5
91
20.2
—
DMO = distal molar occlusion; MMO = mesial molar occlusion; EMO = extreme maxillary overjet; MO = mandibular overjet.
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Type of anomaly
304
T. LAINE
All sounds found to be distorted in this sample were medioalveolar consonants: distortions of Is/-, /r/-, /I/-, /n/-, and /d/. Anterior variants were found in 28 per cent, posterior variants in 5 per cent, lateral variants as well as unclassified ones in 2 per cent of the students. Table 2 shows that in most cases the subjects had one articulatory speech disorder only, nine of them having distortions of at least two consonants, the greatest being one individual who had distortions of five different consonants. Eight persons had anterior variants of different consonants combined with each other and/or with unclassified variants. One individual had
a combination of a posterior and a lateral faulty variant. A log-linear function was fitted to analyse the relationship and interactions between different occlusal anomalies and articulatory speech disorders, considering the possible effects of previous dental treatment and speech therapy. Z-values of ^ 1.96 were considered statistically significant. Results Table 3 shows the statistically significant interactions regarding sagittal occlusal anomalies and different types of misarticulations. Mesial molar occlusion and mandibular overjet were related to consonants produced too far anteriorly (Z-values 3.28 and 2.60, respectively). Slightly less than one-quarter of the subjects without either of these anomalies had anterior variants while more than half of the subjects with these anomalies had consonants that were produced too far anteriorly. Risk ratios of having anterior variants was 4.5 for mesial occlusion and 3.7 for mandibular overjet, respectively. No statistically significant associations were found between distal molar occlusion or extreme maxillary overjet and any of the articulatory speech disorders. With regard to vertical occlusal anomalies, incisal open bite was clearly related to consonants that were produced too far anteriorly (Table 4). Less than one-quarter of the subjects
Table 2 Combinations of different types of articulatory disorders in speech according to errors of place of articulation among Finnishspeaking students (n = 451). Number of faulty variants of consonants
Number of subjects
Proportions of subjects (%)
Cumulative proportions of subjects (%)
AV PV LV UV AV + AV AV+AV+AV+AV+AV AV + UV AV + AV+UV PV+LV
104 16 10 5 1 2 4 I 1
23.1 3.5 2.2 1.1 0.2 0.4 0.9 02 0.2
23.1 26.6 28.8 29 9 30 1 30.5 31.4 31.6 31.8
AV = anterior variant; PV = posterior variant: LV = lateral variant; UV = unclassified variant.
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A detailed description of the method has been published (Laine et al., 1987). All acoustically distorted sounds were diagnosed according to type of sound disorder and faulty place of articulation. In this report, a diagnosis based on place of articulation was used. Placement was categorized as anterior, posterior, lateral or an unclassified variant of the sounds. An anterior variant indicates that the faulty sound has been produced anterior to the correct placement. Correspondingly, posterior variants have been produced posteriorly and lateral ones laterally when compared to the correct place of articulation of the specific sound. Unclassified variants are produced in a correct place, but are acoustically distorted in all phonetical contexts. Articulatory speech disorders were classified into grade 1 and grade 2, the latter indicating a need for treatment.
305
MALOCCLUSION AND SPEECH SOUND PRODUCTION
Table 3 Proportions of subjects with and without articulatory disorders in speech in subjects with sagittal occlusal anomalies (n = 451). Only statistically significant interactions are given. Occlusal anomalies Mesial molar occlusion
Mandibular overjet Yes
No
No
Yes
Articulatory disorders
n
No anterior variants
331
77
9
43
332
76
8
47
99
23
12
57
102
24
9
53
430
100
21
100
434
100
17
100
Anterior variants
n
%
n
%
3.28
Z-value*
%
2.60
* By a fitted log-linear function.
Table 4 Proportions of subjects with and without articulatory disorders in speech in subjects with vertical or transverse occlusal anomalies (n = 451). Only statistically significant interactions are given. Vertical anomalies
Transverse anomalies
Incisal open bite
Lateral cross-bite Yes
No
No
Yes
Articulatory disorders
n
No anterior variants
325
77
15
50
283
77
57
67
96
23
15
50
83
23
28
33
421
100
30
100
366
100
85
100
Anterior variants Total Z-value*
n
%
3.18
%
n
n
%
%
1 97
* By a fitted log-linear function
without open bite had this articulatory disorder while half of the subjects who had incisal open bite also had consonants produced too far anteriorly. With regard to lateral cross-bite the difference was smaller, 23 and 33 per cent, respectively. Risk ratios for producing consonants too far anteriorly were 3.4 times for subjects with open bite and 1.7 times for those with lateral cross-bite compared to individuals without those occlusal anomalies. Based on the results of log-linear function, subjects with mesial molar occlusion and incisal open bite were observed separately. Table 5 lists the subjects with mesial molar occlusion and
shows the combination of mesial occlusion with other occlusal anomalies, as well as the occurrence of misarticulations in those subjects. Twothirds of the subjects with mesial molar occlusion demonstrated articulatory speech disorders, primarily anterior variants that were grade 2. Two students who had several distorted sounds demonstrated a mesial molar occlusion and also an anterior open bite. In addition one also had a lateral cross-bite. Twenty out of thirty subjects with incisal open bite had articulatory speech disorders (Table 6). Six of them had an open bite as a single malocclusion trait, fourteen students had,
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Total
n
%
306
T. LAINE
Table 5 Occurrence of combinations of misarticulations of consonants according to errors of place of articulation in subjects with mesial molar occlusion (n = 21) in young adults.
Table 6 Occurrence of combinations of misarticulations of consonants according to errors of place of articulation in subjects with incisal open bite (H = 30) in young adults.
Occlusal anomalies combined with mesial molar occlusion
Occlusal anomalies combined with incisal open bite
Grade 1 Grade 2
AV PV (n = 3) (n = 4) (n = 2) (n= 1) (n = 1)
MO + cross-bite (n = 1) Cross-bite + scissor bite (n= 1)
AV AV PV
— —
AV+AV+ AV + AV + AV AV + AV + UV AV
MO = manibular overjet; IOB = incisal open bite; AV = anterior vanant; PV = posterior variant; UV = unclassified variant.
in addition to open bite, at least one occlusal anomaly, most often mesial molar occlusion and/or lateral cross-bite. Eight individuals had one mild anterior, posterior or unclassified misarticulation of a consonant. Twelve subjects had more severe, mainly anterior variants, one of them having a combination of five anterior variants and one individual revealing a combination of one unclassified and two anterior variants. Discussion Articulatory speech disorders while not the most severe type, represent 50-60 per cent of all speech disorders (Van Riper, 1978), thus being relatively important in terms of channelling resources for speech therapy. There are a variety of methods for diagnosing articulation disorders in speech. In the present study, both the traditional classification, based on acoustical perception of different sounds (Van Riper, 1978), and spatial classification, describing movements of the tongue during speech sound production, were used. From a functional point of view, diagnosing on the basis of place of articulation seems to be more relevant. Although there are some who suggest that articulation disorders are psychologically based,
None(n=l) None(n = 2) None(n = 2) None(n=l) None(n=l) MMO + MO + cross-bite (n = 3) M MO + MO + cross-bite (" = 2) M MO + MO + cross-bite M MO + MO + cross-bite (n= 1) M MO + MO + cross-bite MMO+MO(n=l) MO + cross-bite (n= 1) MO(/7 = 3) Cross-bite (n = 3) Cross-bite [n= 1) DMO+EMO (n=I) DMO + EMO (/?=1) Cross-bite + lateral open bite
Misarticulation Grade 1 Grade 2 AV — PV UV
— AV — —
AV
— AV
— PV
AV + AV + AV + AV + AV —
— — — — — UV —
AV + AV + UV LV — — AV AV — AV
MMO = mesial molar occlusion; MO = manibular overjet; DMO = distal molar occlusion; EMO = extreme maxillary overjet; AV = anterior variant; PV = posterior variant; UV = unclassified variant; LV = lateral variant.
learned phenomena, it is commonly acknowledged that articulation defects may have both organic and functional origin (Nichols, 1981). Speech movements consist of coarse and fine adjustments, a coarse movement preceding movements involving fine motor control. As the term articulation disorders or phonetic disorders describes an inability to produce certain sounds correctly due to difficulties with the motor production aspects of speech, phonological disorders, on the other hand, places speech sounds within the larger context of language. For individuals whose errors are primarily phonological in the presence of relatively normal motor-phonetic characteristics (Hardcastle et al., 1987), structural deviations are of no importance from an aetiological point of view. In this sample, all articulation disorders were distortions of different consonants, usually representing phonetic errors while phonological
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None (/i = 3) None(n = 3) None ( n - 1) MO + IOB + cross-bite MO + IOB + cross-bite MO + IOB + cross-bite MO + IOB + cross-bite MO + IOB + cross-bite
Misarticulation
MALOCCLUSION AND SPEECH SOUND PRODUCTION
It is obvious from the many reports in the literature that individuals can compensate for rather severe deviations of the orofacial structures and produce speech without distortions.
Although compensation is often mentioned in the literature (Rathbone, 1955; Benediktsson, 1958; Bankson and Byrne, 1962; Lubit, 1967; Bloomer, 1971; Van Riper, 1978; Lehtihalmes, 1984) little is known about the mechanisms involved in compensatory adjustments (Jensen, 1968; Weinberg, 1968; Subtelny et al., 1964, 1972; Kelso et al., 1984). Studies on function of the articulators for normal speech production (Lindblom, 1967; Lindblom and Sundberg, 1971; Subtelny et al., 1968, 1969, 1972; Niimi et al., 1982; Hirose, 1986) are supplemented by studies describing compensation under exceptional conditions, mainly in cleft palate patients (Subtelny et al., 1968, 1969; Warren, 1967, 1986; Dalston et al., 1988; Laine et al., 1988, 1989). There are also similar reports of an experimental nature (Lindblom et al., 1979; Gay et al., 1981; Warren et al., 1980, 1981, 1984; Putnam et al., 1986) demonstrating a better ability to compensate for induced malocclusions rather than natural ones. One interesting point relevant to the role of different types of malocclusion in articulatory speech disorders is that mesial molar occlusion with mandibular overjet occurs only rarely in young children while an incisal open bite and also lateral cross-bite frequently occur during speech development. Longitudinal studies to determine whether children with these occlusal anomalies and articulation disorders have the same faulty sounds at a later age or whether articulatory speech disorders appear later during development of the dentition, would clarify these issues. It is commonly hypothesized that misarticulations of especially /s/ and /r/ sounds are what Hardcastle et al. (1987) call 'residual speech errors', dating from the early stages of speech development. If this is true, any other malocclusion except those existing at the age of 2 to 4-5 years could not possibly have any effect on speech sound production. Finally, it is important to point out that the articulation of speech sounds is the last stage during the production of speech, preceded by respiration, phonation, and resonance. Recent studies have focused on control and regulation of breathing and aerodynamic variables during speech sound production (Smitheran and Hixon, 1981; Warren, 1982, 1986; Putnam et al., 1986; Warren el al., \9%9a,b). In addition, temporal responses of the vocal tract for normal speech utterances (Tuller and Kelso, 1984), as
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errors often comprise substitutions and omissions of different sounds. Previous studies concerning the relationship between malocclusions and speech disorders consist mainly of reports dealing with incisal open bite and distortions of the /s/ sound, although some studies considered tongue thrust swallowing as well. Undoubtedly, misarticulations of fricatives are the most common articulatory speech disorder in many languages and an association between incisal open bite and distortions of the unvoiced linguoalveolar /s/ sounds is the most common finding. Our results were parallel to previous findings. However, in the present sample individuals with mesial molar occlusion and anterior cross-bite showed a higher risk for articulatory speech disorders than those with incisal open bite. In addition, subjects with lateral cross-bite had a greater risk of articulation disorders than those without this occlusal anomaly. Differences between the results reported in this study and previous reports stem primarily from the fact that investigations focused on only one occlusal trait or one type of malocclusion rather than several occlusal traits. The only other study of mesial molar occlusion and articulation proficiency (Guay et al., 1978) reported findings that are consistent with the present results. Interestingly, in this and the Guay et al. study, mesial occlusions were mild in character. There are several explanations why individuals with a mesially located mandible and tongue might have difficulties in producing a correct unvoiced linguoalveolar /s/ sound. It is one of the most difficult sounds to produce, requiring precise placement and function of both the tip and the blade of the tongue as well as space enough anteriorly to the tip of the tongue in the most anterior part of the palate. Deviant structure or volume of the posterior part of the oropharynx may complicate adequate placement of the tongue. Indeed, subjects with Class III incisor relationship have been reported to have a different pattern of movement of the mandible (Howell, 1987) which may affect the close co-ordination of the lips, tongue, and mandible, required for accurate speech sound production (Lindblom and Sundberg, 1971).
307
308
Address for correspondence
Tellervo Laine Department of Orthodontics Faculty of Dentistry University of Kuopio P.O. Box 1627
70211 Kuopio Finland Acknowledgements
The author wishes to thank Helena Rantala, B.A., and Arja-Liisa Linnasalo, M.A., Department of Special Education, University of Jyvaskyla, for diagnosing speech disorders. The study was financially supported by the Emil Aaltonen Foundation and by the Finnish Dental Society. References Bankson N W, Byrne M C 1962 The relationship between missing teeth and selected consonant sounds. Journal of Speech and Hearing Disorders 27: 341-348 Benediktsson E 1958 Variation in tongue and jaw position in 's' sound production in relation to front teeth occlusion. Acta Odontologica Scandinavica 15: 275-303 Bernstein M 1954 The relation of speech defects and malocclusion. American Journal of Orthodontics 40: 149-150
Bjork A, Krebs A, Solow B 1964 A method for epidemiologlcal registration of malocclusion. Acta Odontologica Scandinavica 22: 27-41 Bloomer H H 1971 Speech defects associated with dental abnormalities and malocclusions. In- Travis L E (ed ) Handbook of speech pathology. Prentice-Hall, Englewood Cliffs, NJ, pp. 608-652 Blyth P 1959 The relationship between speech, tongue behaviour, and occlusal abnormalities. Dental Practitioner 10: 11-20 Dalston R M, Warren D W, Morr K E, Smith L 1988 Intraoral pressure and its relationship to velopharyngeal inadequacy. Cleft Palate Journal 25: 210-219 Gay T, Lindblom B, Lubker J 1981 Production of biteblock vowels: Acoustic equivalence by selective compensation. Journal of Acoustical Society of America 69: 802-810 Guay A H, Maxwell D L, Beecher R 1978 A radiographic study of tongue posture at rest and during the phonation of /s/ in Class III malocclusion. Angle Orthodontist 48' 10-22 Hardcastle W J, Morgan Barry R A, Clark C J 1987 An instrumental phonetic study of lingual activity in articulation-disordered children. Journal of Speech and Hearing Research 30. 171-184 Hirose H 1986 Pathophysiology of motor speech disorders (dysarthria). Folia Phoniatrica 38. 61-88 Howell P G T 1987 The variation in the size and shape of the human speech pattern with incisor-tooth relation. Archives of Oral Biology 32: 587-592 Ingervall B, Sarnas K.-V 1962 Comparison of dentition in lispers and non-hspers. Odontologisk Revy 13: 344-354 Jensen R 1968 Anterior teeth relationship and speech. Acta Radiologica suppl 276: 1-69 Kelso J A S, Tuller B, Vatikiotis-Bateson E, Fowler C A 1984 Functionally specific articulatory cooperation following jaw perturbations during speech: Evidence for coordinative structures. Journal of Experimental Psychology: Human Perception and Performance 10: 812-832 Klechak T L, Bradley D P, Warren D W 1976 Anterior open bite and oral port constriction. Angle Orthodontist 46: 232-242 Laine T 1984 Morphology of the dentition in young adults. An epidemiological study on Finnish students. Proceedings of the Finnish Dental Society 80: suppl. IV, 1-42 Laine T 1987 Associations between articulatory disorders in speech and occlusal anomalies. European Journal of Orthodontics 9: 144-150 Laine T, Hausen H 1982 Cross-sectional study of orthodontic treatment and missing of permanent teeth in two birth cohorts of Finnish students according to sex. Community Dentistry and Oral Epidemiology 10: 209-213 Laine T. Hausen H 1983 Occlusal anomalies in Finnish students related to age, sex, absent permanent teeth and orthodontic treatment. European Journal of Orthodontics 5: 125-131 Laine T, Hausen H 1985 Space anomalies, missing permanent teeth and orthodontic treatment. Angle Orthodontist 55: 242-250 Laine T, Linnasalo A-L, Jaroma M 1987 Articulatory disorders in speech among Finnish speaking students
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well as to compensate structural deviations, have been studied (Warren et ai, 1989a). Studies on the linguistic aspects of speech, though extensive in number and of essential importance in the process of expressing thoughts as words, are outside the scope of this report. However, it should be realized that anatomical variation may play a minor role in this process. In summary, studies dealing with the developmental aspects of speech in relation to occlusion and 'compensatory' speech responses to the presence of structural deviations are clearly lacking, partly due to methodological difficulties. Regarding single traits of malocclusion, the present and earlier results of this sample of young adults indicate that individuals with mesial molar occlusion, mandibular overjet, incisal open bite and/or lateral cross-bite have a higher risk for articulatory speech disorders, especially consonants produced too far anteriorly. Incisal open bite alone is rarely associated with articulatory speech disorders, but if present they tend to be mild. Incisal open bite combined with other occlusal anomalies, especially with mesial occlusion, is related more often to more severe misarticulations.
T. LAINE
MALOCCLUSION AND SPEECH SOUND PRODUCTION according to age, sex and speech therapy Journal of Communication Disorders 20. 327-338 Laine T, Warren D W, Dalston R M, Hairfield W M, Morr K E 1988 Intraoral pressure, nasal pressure and airflow rate in cleft palate speech. Journal of Speech and Hearing Research 31: 432-437 Laine T, Warren D W, Dalston R M, Morr K E 1989 Effects of velar resistance on speech aerodynamics European Journal of Orthodontics II. 52-58 Lehtihalmes M 1984 Puheen fysiologian perusteista. In Narhi M, Johansson G (eds) Purentaelimen Fysiologia Turun Yliopiston Hammaslaaketieteen laitoksen off-set paino, Turku, pp. 201-210
Lindblom B E F, Sundberg E F 1971 Acoustical consequences of lip, tongue, jaw, and larynx movement. Journal of Acoustical Society of America 50: 1166-1179 Lindblom B, Lubker J, Gay T 1979 Formant frequencies of some fixed-mandible vowels and a model of speech motor programming by predective simulation Journal of Phonetics 7: 147-161 Lubit E C 1967 The relationship of malocclusion and faulty speech articulation Journal of Oral Medicine 22: 47-55 Nichols A C 1981 Articulation—Organic factors. In: Rieber R W (ed.) Communication Disorders. Plenum Press, New York and London, pp 3-19 Niimi S, Bell-Berti F, Harris K S 1982 Dynamic aspects of velopharyngeal closure. Folia Phoniatrica 34: 246—257 Putnam A H B, Shelton R L, Kastner C V 1986 Intraoral air pressure and oral air flow under different bleed and bite-block conditions. Journal of Speech and Hearing Research 29: 37-49 Rathbone J S 1955 Appraisal of speech defects in dental anomalies Angle Orthodontist 25' 42-48 Smitheran J R, Hixon T J 1981 A clinical method for estimating laryngeal airway resistance during vowel production. Journal of Speech and Hearing Disorders 46' 138-146 Subtelny J D, Mestre J C, Subtelny J D 1964 Comparative study of normal and defective articulation of/s/ as related to malocclusion and deglutition. Journal of Speech and Hearing Disorders 29- 269-285 Subtelny J D, McCormack R M, Subtelny J D, Worth J H, Cramer L M, Runyon J C, Rosenblum R M 1968
Synchronous recording of speech with associated physiological and pressure-flow dynamics: instrumentation and procedures. Cleft Palate Journal 5: 93-115 Subtelny J D, Kho G H, McCormack R M, Subtelny J D 1969 Multidimensional analysis of bilabial stop and nasal consonants—cineradiographic and pressure-flow analysis. Cleft Palate Journal 6- 263-289 Subtelny J D, Oya N, Subtelny J D 1972 Cineradiographic study of sibilants. Folia Phoniatnca 24: 30-50 Tuller B, Kelso J A S 1984 The timing of articulatory gestures- Evidence for relational invariants Journal of Acoustical Society of America 76: 1030-1036 Van Riper C 1978 Speech Correction Principles and methods. Prentice-Hall, Englewood Cliffs, NJ Warren D W 1967 Nasal emission of air and velopharyngeal function. Cleft Palate Journal 4- 148-156 Warren D W 1982 Aerodynamics of speech. In: Lass N J, McReynolds L V, Northern J L, Yoder D E, (eds) Speech, language and hearing. W B Saunders, Philadelphia, pp. 219-245 Warren D W 1986 Compensatory speech behaviors in individuals with cleft palate- A regulation/control phenomenon? Cleft Palate Journal 23 251-260 Warren D W, Nelson G R, Allen G 1980 Effects of increased vertical dimension on size of constriction port and fricative sound intelligibility Journal of Acoustical Society of America 67: 1828-1831 Warren D W, Hall D J, Davis J 1981 Oral port constriction and pressure-airflow relationships during sibilant productions. Folia Phoniatnca 33 380-393 Warren D W, Allen G. King H A 1984 Physiologic and perceptual effects of induced anterior open bite. Folia Phoniatnca 36. 164-173 Warren D W, Dalston R M, Morr K E, Hairfield W M, Smith L R 1989a The speech regulating system, temporal and aerodynamic responses to velopharyngeal inadequacy. Journal of Speech and Hearing Research 32. 566-575 Warren D W, Morr K E, Putnam Rochet A, Dalston R M 1989ft Respiratory response to a decrease in velopharyngeal resistance. Journal of Acoustical Society of Amenca 86 917-924 Weinberg B 1968 A cephalometric study of normal and defective /s/ articulation and variations in incisor dentition. Journal of Speech and Hearing Research 11: 288-300
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Lindblom B 1967 Vowel duration and a model of lip mandible coordination. Speech Transmission Laboratory' Quarterly Progress Status Report 4: 1-29
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