0003-9969192 55.00+O.OO Copyright‘0 1992 Pergamon Press Ltd
Arch orolBio1. Vol. 31,So. II,pp. 89%399, 1992 Printedin Great Britain.All rightsreserved
ASSOCIATIONS AMONG DIFFERENT OROFACIAL DYSFUNCTIONS IN 6-8 YEAR OLDS M.
TELLERVO LAINE,’ RII~A
H. PAHKALA,’ S. MARJATTA JAROMA’
and MAFUJ.
QVARNSTR~M’
‘Department of Orthodontics, Faculty of Dentistry, University of Kuopio and %epartment Otolaryngology and Phoniatrics, Kuopio University Hospital. 70211 Kuopio. Finland
of
(Accepted 28 May 1992)
Summary-Associations among several orofacial dysfunctions such as articulatory speech disorders, craniomandibular disorders (CMD) and problems in coordinating the orofacial muscles were examined in two groups of Finnish first-graders, i.e. children with and without speech disorders. In the whole sample of 287 subjects the mean age was 7.5 yr. A speech therapist diagnosed articulatory speech disorders and a phoniatrician examined the morphology and function of the articulators. Signs and symptoms of CMD, capacity for mandibular movement, and prevalence of occhrsal interferences were examined by a dentist. Deviations in motor skills. but not in morphology of the articulators, were associated with speech disorders. The findings also suggested that capacity for mandibular movement, deviation of the jaw during maximal mouth opening and occlusal interferences were related to certain speech disorders among these 6-8 yr olds. Different orofacial dysfunctions appear to be associated with each other during growth. Key words: craniomandibular
disorder, articulatory speech disorders, orofacial dysfunctions, children.
I>-TRODUCTIO;U
To our knowledge, no studies of the relations among various orofacial dysfunctions, such as CMD, speech misarticulation and problems with orofacial motor functions exist. The results of our preliminary study showed, however, that children with articulatory speech disorders had more CMD than the controls (Ettala-Ylitalo and Laine, 1991). There is a lack of studies on coordination of the speech articulators in children with misarticulation. Our purpose now was to examine in a group of first-graders the associations between (1) different types of articulatory speech disorders, (2) morphology and function of the speech articulators and (3) signs and symptoms of CMD. The effects of gender and developmental stage of the dentition were also considered. MATERIALS AND XlETHODS
The sample was composed of two groups of firstgraders in Kuopio, a town of 80,000 inhabitants in Finland. Group 1 consisted of children diagnosed by special-education teachers as having an articulatory speech disorder and who were referred for treatment to the Department of Otolaryngology and Phoniattics at Kuopio University Hospital. In group 2 all the first-graders of two elementary schools in Kuopio were included. None of the children had a hearing deficiency. In group 1 there were 157 children (67 girls and 90 boys) and in group 2, 130 children (67 girls and 63 boys). In both groups the mean and median age was 7.5 yr. The age range was 6.5-8.7 for group 1 and 6.9-8.3 for group 2. Articulatory disorders, if any, were diagnosed by the same speech therapist according to disorders in Abbreuiarions:
CMD, craniomandibular disorder; TMJ, temporomandibular joint.
different sounds and errors in the placement of articulation. Disorders in different sounds were categorized into correct, distorted, substituted or omitted sounds. The placement of articulation was observed by visual inspection of the mouth and the movements of the articulators, especially those of the tongue tip and lips. Both spontaneous speech and articulation of test words were examined using the Remes Articulation Test (Remes, 1975) for the Finnish language. A more detailed description of the clinical examination is presented elsewhere (Qvamstriim, Laine and Jaroma, 1991). At the same time the morphology and function of the articulators were recorded clinically by the same experienced phoniatrician using the method developed for diagnostics at the Department of Otolaryngology and Phoniatrics (Appendix). Tonus of the lips, width and length of the tongue and length of the soft palate were assessed. The functioning of the tongue tip and the lips during different tasks was judged to be either accurate, inaccurate or failed. The coordination of the repeated movements was assessed to be accurate if the subject was able to repeat the movement more than five times in 10 s. Signs of CMD (deflection of the mandible on opening and closing, palpatory tenderness of the masticatory muscles, TMJ sounds, TMJ tenderness on movement and restricted movements of the mandible) and occlusal recordings (interferences and slide between the retruded and intercuspal positions), which are described in detail elsewhere (Pahkala et al., 1991a) were registered during clinical examinations by the same dentist. During the same appointment, symptoms of CMD (headache, bruxism) were noted using a questionnaire. Hard stone casts were prepared for detailed registration of the dental occlusion and developmental stage of the dentition. For the lateral segments, stage of eruption of the permanent teeth was classified as 895
51. TELLERV~ LAM ef ol.
896
Table 1. Relationship between sounds produced too posteriorly (0 = no, 1 = yes) and structure and function of the articulators, prevalence of occlusal recordings and clinical signs and symptoms of CMD, considering the effects of gender (girls = 0, boys = I), age (months) and developmental stage of the dentition among Finnishspeaking first-graders as estimated by logistic regression model Variable Protrusive interferences (no = 0, yes = I) Mediotrusive interferences (no =O, yes = 1) Degree of inaccuracy of the movements* by mainly the longitudinal muscles of the tongue (0,6) Degree of inaccuracy of coordination of movements* by other muscles of the tongue (0.8) Gender
Regression coefficient -0.655 0.429
-0.440
0.166 0.676
SE
Regression coefficient/SE
0.220
- 2.98
0.215
2.00
0.210
0.05 I 0.213
-2.10
3.26 3.17
*See Materials and Methods.
p = 0.481. follows: 0 = at least
one molar erupting, 1 = all molars in occlusion. For the anterior segments the mean value of the relative height (%) of the permanent teeth was calculated by comparing the height of
each visible crown to the mean height of the corresponding tooth in the Finnish normative data (Pahkala, Laine and Lammi, 1991b). In the previous analyses of the present sample malocclusions were not related to speech disorders in first-graders (Palviainen and Laine, 1990), so variation in dental occlusion and expression of malocclusions were not included in the present analyses. Multiple logistic regression models were fitted in order to analyse associations between each type of articulatory speech disorder and morphology and function of the speech articulators, CMD signs and symptoms and occlusal recordings, considering the effects of age, gender and developmental stage of the dentition. For all comparisons, Z values > 1.96 were considered to be statistically significant. RESULTS
In morphological features of the articulators, no differences between the groups were found. Almost all the children studied had normal oral structure. Correlation between two variables describing the
function of the articulators, namely (a) degree of accuracy in coordinating tongue movements of mainly muscles other than longitudinal ones and (b) voiced raspberry, was high (r = 0.70). Thus, these variables were included in the models separately (models A and B, respectively). Tables 1-3 give the results with the former (a) variable included. The results of the models with the latter (b) variable are given in the text. Age was the only variable associated with sounds produced too anteriorly. According to both logistic models, the risk of having these misarticulations decreased with age (Z value = -2.74). The risk for sounds produced too posteriorly (Table 1) increased with mediotrusive interferences and with problems in coordinating movements of all except the longitudinal tongue muscles. On the other hand, protrusive interferences and problems in the movements of mainly the longitudinal tongue muscles decreased this risk. In model B, protrusive interferences were also negatively related to this speech misarticulation (Z value = -2.24). Boys were more prone to have sounds produced too posteriorly (Z value = 3.05). With a large capacity for protrusion of the mandible and with problems in coordinating the movements of muscles other than the longitudinal
Table 2. Relationship between lateral misarticulations (0 = no, 1 = yes) and structure and function of the articulators, prevalence of occlusal recordings and clinical signs and symptoms of CMD, considering the effects of gender (girls = 0, boys = I), age (months) and developmental stage of the dentition among Finnish-speaking firstgraders as estimated by logistic regression model Variable Maximal protrusion (mm) of the mandible Degree of inaccuracy of coordination of movements* by other muscles of the tongue (0,8) *See Materials and Methods. p = 0.479.
Regression coefficient
SE
Regression coefficient/SE
0.176
0.079
2.23
0.134
0.067
1.99
897
Orofacial dysfunctions in children Table 3. Relationship between misarticulations produced in a correct place (0 = no,
1 = yes) and structure and function of the articulators, prevalence of occlusal recordings and clinical signs and symptoms of CMD, considering the effects of gender (girls = 0, boys = l), age (months) and developmental stage of the dentition among Finnish-speaking first-graders as estimated by logistic regression model Variable Maximal opening (mm) of the mandible Deviation on maxima1 opening of the mandible (0.1) Degree of inaccuracy’ of the movements* by mainly the longitudinal muscles of the tongue (0,6) Developmental stage of the maxillary and mandibular permanent incisors (%)
Regression coefficient -0.064
SE 0.022
Regression coefficient SE -2.94
0.549
0.233
2.35
0.400
0.118
3.39
-0.008
0.004
-2.05
*See Materials and Methods.
p = 0.595. tongue muscles, the risk for lateral misarticulation increased. In addition to large protrusive capacity,
a problem with voiced raspberry was related to increased risk of lateral misarticulations in model B (Z values = 2.42 and 2.43, respectively). Deviation of the mandible during mouth opening and problems with movements of the longitudinal muscles of the tongue in particular were positively associated with other misarticulations, i.e. auditively deviant sounds but produced in the correct place of articulation, while high maximal-opening capacity of the mandible was negatively associated with this speech deficiency (Table 3). For models A and B the results were identical. DISCUSSIOS
Unlike those in adults, CMD in children are not necessarily considered to be pathological but rather are connected with normal growth and maturation of the orofacial functions (Dibbets, van der Weele and Uildrics, 1985; Copray, Dibbets and Kantomaa, 1988). During the development of the dentition there is often occlusal disharmony due to tooth eruption. Later, after the permanent canines are fully erupted, occlusion is stabilized (Egermark-Eriksson, 1982; Nilner and Kopp, 1983). In children, the TMJ is not fully developed either (Proffit, 1986) and it takes time until the adult pattern of mandibular movements is adopted. Development of speech articulation is also related to age and maturation of orofacial motor functions (Nichols, 1981; Robbins and Klee, 1987). In this study, therefore, age, gender and eruptional stage of the dentition were included in the data analyses as confounding factors. During the formation of a certain sound the position of the mandible varies according to the sound preceding or following it. This has been confirmed, e.g. for ‘s’-sound in a kinesiographic study (George, 1983). Therefore, we registered misarticulations only if they occurred in all phonetic contexts. In our sample of almost 300 children, movements and coordination of the speech articulators were evaluated clinically. More precise information on changes in mandibular position and
intraoral articulatory postures can lx documented using sophisticated techniques; this study served partly to discover the smaller subgroups that could be examined using these methods to give more detailed information on speech motor control. Protrusive and mediotrusive interferences were associated with laterally produced faulty sounds. Unexpectedly, their relations to this speech disorder were opposite. Deviation of the jaw during mouth opening was related to other misarticulations. In addition, the capacity for mandibular movement was related to speech errors, indicating that children with articulatory speech disorders were not able to open their mouth as wide as the controls but that their protrusive capacity was greater than in children with correct speech production. These findings might be due either to disturbances in peripheral factors (interferences) that assimilate orofacial structures to certain jaw movements or to poor fine-motor control of these muscles. Interestingly, certain variables reflecting motor speech skills were positively related to other misarticulations but negatively related to sounds produced too far posteriorly. In general, maturation of oral functions, such as swallowing and speech, follows a gradient from anterior to posterior (Proffit, 1986). Although immaturity of the longitudinal tongue muscles could predispose a child to sounds produced too far anteriorly, it is logical that this was not associated with sounds produced too far posteriorly. In the Finnish language, ‘r’ is a multiple trilled medioalveolar consonant and the most common posterior misarticulation is ‘r’uvularis. Sounds produced too far posteriorly were here associated with problems in coordinating muscles other than the longitudinal muscles of the tongue. Early in life, the posterior airway space is relatively small and this favours an anterior position of the tongue, which is later modified by involution of lymphoid tissue and mandibular growth, allowing more space for the tongue (Proffit and Mason, 1975; Linder-Aronson and Leighton, 1983). Interestingly, in a recent kinesiographic study, Williamson, Hall and Zwemer (1990) found that patients with CMD tended to swallow with their teeth apart and with
898
M. TELLFXVO LAW
excessive vertical and lateral mandibular movements. We did not study swallowing patterns, but our findings and those of Williamson er al. (1990) are parallel in that deviant function of the orofacial muscles seems to manifest itself during different activities. In summary, deviations in function, but not in morphology, of the orofacial muscles were associated with speech disorders. Among the 6-8-yr-old children studied, some signs of CMD, occlusal interferences, mandibular movement capacity and several variables reflecting orofacial motor skills were also related to certain disorders in speech sound production. Several orofacial dysfunctions seem to be associated with each other during growth. Longitudinal study of our sample will give information on whether orofacial dysfunctions improve with the maturation of finemotor control or whether dysfunctions become fixed with age. Acknowledgernenw-This study was supported by the Academy of Finland, the Finnish Dental Society and the North Savo Fund of the Finnish Cultural Foundation.
REFERENCES
Copray J. C. V. M., Dibbets J. M. H. and Kantomaa T. (1988) The role of condylar cartilage in the development of the temporomandibular joint. Angle Orthod. 58,
et al.
George J. P. (1983) Using the kinesiograph to measure mandibular
movements
during speech: a pilot study.
J. prosthet. Dent. 49, 263-210.
Linder-Aronson S. and Leighton B. C. (1983) A longitudinal study of the development of the posterior nasopharyngeal wall between 3 and 16 years of age. Eur. J. Orlhod. 5, 47-58.
Nichols
A. C. (1981) Articulation-organic
factors.
In
Communication Disorders (Ed. Rieber R. W.), pp. 3-19.
Plenum Press, New York. Nilner M. and Kopp S. (1983) Distribution by age and sex of functional disturbances and diseases of the stomatoanathic system in 7-18 year olds. Swed. dent. J. 7, 191-19r8. Pahkala R., Laine T., Narhi M., Ettala-Ylitalo U.-M. (1991a) Relationship between craniomandibular dysfunction and pattern of speech sound production in a series of first-graders. Eur. J. Orthod. 13. 378-385. Pahkala R., Lame T. and Lammi S. (199lb)‘DevelopmentaI stage of the dentition and speech sound production in a series of first-grade schoolchildren. J. craniofuc. Gene?. deu. Biol. 11, 170-175. Palviainen S. and Laine T. (1990) The role of developmental stage of occlusion for articulatory disorders in speech among first-graders. J. C/in. Pediutr. Dent. 15, 33-38. Protlit W. R. (1986) Contemporary Orthodontics. CV Mosby Co., St Louis, MO. Proffit W. R. and Mason R. M. (1975) Myofunctional therapy for tongue-thrusting: background and recommendations. J. Am. den!. Ass. 90, 403-411. Qvarnstriim M., Laine T. and Jaroma M. (1991) Place of articulation in articulatory speech disorders of different sounds in a group of Finnish first-graders. Fohu Phoniuw. 43, 161-170.
369-380.
Dibbets J. M. H., van der Weele L. Th. and Uildrics A. K. J. (1985) Symptoms of TMJ dysfunction: indicators of growth patterns? J. Pedodonr. 9, 265-284. Egermark-Eriksson I. (1982) Mandibular dysfunction in children and individuals with dual bite. Swed. dent. J. 6, (suppl. 10). Ettaia-Ylitalo U.-M. and Laine T. (1991) Functional disturbances of the masticatory system in relation to articulatory disorders of speech in a group of 6-8-year-old children. Archs orul Biol. 36, 189-194.
Remes K. (1975) Artikulaatiotesti, kuvakortisto puheenkehityksen ja linnevirheisyyden tutkimiseen ja tarkkailuun. Koulun erityispalvelu Oy. Robbins J. and Klee T. (1987) Clinical assessment of oropharyngeal motor development in young children. J. speech Hear. Disord. 52, 271-277.
_
-
Williamson E. H.. Hall J. T. and Zwemer J. D. (1990) Swallowing pattkrns in human subjects with and without temporomandibular dysfunction. Am. J. Orrhod. Denrofat. Orthop. 98, 507-511.
(For Appendix see opposite)
899
Orofacial dysfunctions in children APPENDIX Morphology of the articulators (inspection) Tonus of lips
Width of tongue
Length of tongue
Length of soft palate
0 hypotonic 1 normal 2 hypertonic 0 decreased 1 normal 2 increased 0 decreased 1 normal 2 increased 0 adequate I short
Function of the articulators
Soft palate/ A hh/
0 adequate 1 inadequate Accurate
Tongue movements by mainly the longitudinal muscles of the tongue Tip out-in Tip side-to-side Tip up-down Coordination* of the tongue movements by mainly the longitudinal muscles Tip out-in Tip side-to-side Tip up-down Tongue movements by other than longitudinal muscles: tip round the lips Left to right Right to left Coordination of the tongue movements by other muscles: tip round the lips Left to right Right to left Raspberry-unvoiced Raspberry-coordination Raspberry-voiced DDK/te-de/ Lip movements Pucker-smile Smack Trill with lips Pucker-smile coordination Whistle
Inaccurate
Failed
0 0 0
2 2 2
0 0 0
2 2 2
0
1
0
1
2 2
*In coordination of the movements: accurate, > 5 repetitions in 10 s; inaccurate, 1-5 repetitions in 10 s; failed, no repetition:.
Arch orolBio1. Vol. 31,So. II,pp. 89%399, 1992 Printedin Great Britain.All rightsreserved
ASSOCIATIONS AMONG DIFFERENT OROFACIAL DYSFUNCTIONS IN 6-8 YEAR OLDS M.
TELLERVO LAINE,’ RII~A
H. PAHKALA,’ S. MARJATTA JAROMA’
and MAFUJ.
QVARNSTR~M’
‘Department of Orthodontics, Faculty of Dentistry, University of Kuopio and %epartment Otolaryngology and Phoniatrics, Kuopio University Hospital. 70211 Kuopio. Finland
of
(Accepted 28 May 1992)
Summary-Associations among several orofacial dysfunctions such as articulatory speech disorders, craniomandibular disorders (CMD) and problems in coordinating the orofacial muscles were examined in two groups of Finnish first-graders, i.e. children with and without speech disorders. In the whole sample of 287 subjects the mean age was 7.5 yr. A speech therapist diagnosed articulatory speech disorders and a phoniatrician examined the morphology and function of the articulators. Signs and symptoms of CMD, capacity for mandibular movement, and prevalence of occhrsal interferences were examined by a dentist. Deviations in motor skills. but not in morphology of the articulators, were associated with speech disorders. The findings also suggested that capacity for mandibular movement, deviation of the jaw during maximal mouth opening and occlusal interferences were related to certain speech disorders among these 6-8 yr olds. Different orofacial dysfunctions appear to be associated with each other during growth. Key words: craniomandibular
disorder, articulatory speech disorders, orofacial dysfunctions, children.
I>-TRODUCTIO;U
To our knowledge, no studies of the relations among various orofacial dysfunctions, such as CMD, speech misarticulation and problems with orofacial motor functions exist. The results of our preliminary study showed, however, that children with articulatory speech disorders had more CMD than the controls (Ettala-Ylitalo and Laine, 1991). There is a lack of studies on coordination of the speech articulators in children with misarticulation. Our purpose now was to examine in a group of first-graders the associations between (1) different types of articulatory speech disorders, (2) morphology and function of the speech articulators and (3) signs and symptoms of CMD. The effects of gender and developmental stage of the dentition were also considered. MATERIALS AND XlETHODS
The sample was composed of two groups of firstgraders in Kuopio, a town of 80,000 inhabitants in Finland. Group 1 consisted of children diagnosed by special-education teachers as having an articulatory speech disorder and who were referred for treatment to the Department of Otolaryngology and Phoniattics at Kuopio University Hospital. In group 2 all the first-graders of two elementary schools in Kuopio were included. None of the children had a hearing deficiency. In group 1 there were 157 children (67 girls and 90 boys) and in group 2, 130 children (67 girls and 63 boys). In both groups the mean and median age was 7.5 yr. The age range was 6.5-8.7 for group 1 and 6.9-8.3 for group 2. Articulatory disorders, if any, were diagnosed by the same speech therapist according to disorders in Abbreuiarions:
CMD, craniomandibular disorder; TMJ, temporomandibular joint.
different sounds and errors in the placement of articulation. Disorders in different sounds were categorized into correct, distorted, substituted or omitted sounds. The placement of articulation was observed by visual inspection of the mouth and the movements of the articulators, especially those of the tongue tip and lips. Both spontaneous speech and articulation of test words were examined using the Remes Articulation Test (Remes, 1975) for the Finnish language. A more detailed description of the clinical examination is presented elsewhere (Qvamstriim, Laine and Jaroma, 1991). At the same time the morphology and function of the articulators were recorded clinically by the same experienced phoniatrician using the method developed for diagnostics at the Department of Otolaryngology and Phoniatrics (Appendix). Tonus of the lips, width and length of the tongue and length of the soft palate were assessed. The functioning of the tongue tip and the lips during different tasks was judged to be either accurate, inaccurate or failed. The coordination of the repeated movements was assessed to be accurate if the subject was able to repeat the movement more than five times in 10 s. Signs of CMD (deflection of the mandible on opening and closing, palpatory tenderness of the masticatory muscles, TMJ sounds, TMJ tenderness on movement and restricted movements of the mandible) and occlusal recordings (interferences and slide between the retruded and intercuspal positions), which are described in detail elsewhere (Pahkala et al., 1991a) were registered during clinical examinations by the same dentist. During the same appointment, symptoms of CMD (headache, bruxism) were noted using a questionnaire. Hard stone casts were prepared for detailed registration of the dental occlusion and developmental stage of the dentition. For the lateral segments, stage of eruption of the permanent teeth was classified as 895
51. TELLERV~ LAM ef ol.
896
Table 1. Relationship between sounds produced too posteriorly (0 = no, 1 = yes) and structure and function of the articulators, prevalence of occlusal recordings and clinical signs and symptoms of CMD, considering the effects of gender (girls = 0, boys = I), age (months) and developmental stage of the dentition among Finnishspeaking first-graders as estimated by logistic regression model Variable Protrusive interferences (no = 0, yes = I) Mediotrusive interferences (no =O, yes = 1) Degree of inaccuracy of the movements* by mainly the longitudinal muscles of the tongue (0,6) Degree of inaccuracy of coordination of movements* by other muscles of the tongue (0.8) Gender
Regression coefficient -0.655 0.429
-0.440
0.166 0.676
SE
Regression coefficient/SE
0.220
- 2.98
0.215
2.00
0.210
0.05 I 0.213
-2.10
3.26 3.17
*See Materials and Methods.
p = 0.481. follows: 0 = at least
one molar erupting, 1 = all molars in occlusion. For the anterior segments the mean value of the relative height (%) of the permanent teeth was calculated by comparing the height of
each visible crown to the mean height of the corresponding tooth in the Finnish normative data (Pahkala, Laine and Lammi, 1991b). In the previous analyses of the present sample malocclusions were not related to speech disorders in first-graders (Palviainen and Laine, 1990), so variation in dental occlusion and expression of malocclusions were not included in the present analyses. Multiple logistic regression models were fitted in order to analyse associations between each type of articulatory speech disorder and morphology and function of the speech articulators, CMD signs and symptoms and occlusal recordings, considering the effects of age, gender and developmental stage of the dentition. For all comparisons, Z values > 1.96 were considered to be statistically significant. RESULTS
In morphological features of the articulators, no differences between the groups were found. Almost all the children studied had normal oral structure. Correlation between two variables describing the
function of the articulators, namely (a) degree of accuracy in coordinating tongue movements of mainly muscles other than longitudinal ones and (b) voiced raspberry, was high (r = 0.70). Thus, these variables were included in the models separately (models A and B, respectively). Tables 1-3 give the results with the former (a) variable included. The results of the models with the latter (b) variable are given in the text. Age was the only variable associated with sounds produced too anteriorly. According to both logistic models, the risk of having these misarticulations decreased with age (Z value = -2.74). The risk for sounds produced too posteriorly (Table 1) increased with mediotrusive interferences and with problems in coordinating movements of all except the longitudinal tongue muscles. On the other hand, protrusive interferences and problems in the movements of mainly the longitudinal tongue muscles decreased this risk. In model B, protrusive interferences were also negatively related to this speech misarticulation (Z value = -2.24). Boys were more prone to have sounds produced too posteriorly (Z value = 3.05). With a large capacity for protrusion of the mandible and with problems in coordinating the movements of muscles other than the longitudinal
Table 2. Relationship between lateral misarticulations (0 = no, 1 = yes) and structure and function of the articulators, prevalence of occlusal recordings and clinical signs and symptoms of CMD, considering the effects of gender (girls = 0, boys = I), age (months) and developmental stage of the dentition among Finnish-speaking firstgraders as estimated by logistic regression model Variable Maximal protrusion (mm) of the mandible Degree of inaccuracy of coordination of movements* by other muscles of the tongue (0,8) *See Materials and Methods. p = 0.479.
Regression coefficient
SE
Regression coefficient/SE
0.176
0.079
2.23
0.134
0.067
1.99
897
Orofacial dysfunctions in children Table 3. Relationship between misarticulations produced in a correct place (0 = no,
1 = yes) and structure and function of the articulators, prevalence of occlusal recordings and clinical signs and symptoms of CMD, considering the effects of gender (girls = 0, boys = l), age (months) and developmental stage of the dentition among Finnish-speaking first-graders as estimated by logistic regression model Variable Maximal opening (mm) of the mandible Deviation on maxima1 opening of the mandible (0.1) Degree of inaccuracy’ of the movements* by mainly the longitudinal muscles of the tongue (0,6) Developmental stage of the maxillary and mandibular permanent incisors (%)
Regression coefficient -0.064
SE 0.022
Regression coefficient SE -2.94
0.549
0.233
2.35
0.400
0.118
3.39
-0.008
0.004
-2.05
*See Materials and Methods.
p = 0.595. tongue muscles, the risk for lateral misarticulation increased. In addition to large protrusive capacity,
a problem with voiced raspberry was related to increased risk of lateral misarticulations in model B (Z values = 2.42 and 2.43, respectively). Deviation of the mandible during mouth opening and problems with movements of the longitudinal muscles of the tongue in particular were positively associated with other misarticulations, i.e. auditively deviant sounds but produced in the correct place of articulation, while high maximal-opening capacity of the mandible was negatively associated with this speech deficiency (Table 3). For models A and B the results were identical. DISCUSSIOS
Unlike those in adults, CMD in children are not necessarily considered to be pathological but rather are connected with normal growth and maturation of the orofacial functions (Dibbets, van der Weele and Uildrics, 1985; Copray, Dibbets and Kantomaa, 1988). During the development of the dentition there is often occlusal disharmony due to tooth eruption. Later, after the permanent canines are fully erupted, occlusion is stabilized (Egermark-Eriksson, 1982; Nilner and Kopp, 1983). In children, the TMJ is not fully developed either (Proffit, 1986) and it takes time until the adult pattern of mandibular movements is adopted. Development of speech articulation is also related to age and maturation of orofacial motor functions (Nichols, 1981; Robbins and Klee, 1987). In this study, therefore, age, gender and eruptional stage of the dentition were included in the data analyses as confounding factors. During the formation of a certain sound the position of the mandible varies according to the sound preceding or following it. This has been confirmed, e.g. for ‘s’-sound in a kinesiographic study (George, 1983). Therefore, we registered misarticulations only if they occurred in all phonetic contexts. In our sample of almost 300 children, movements and coordination of the speech articulators were evaluated clinically. More precise information on changes in mandibular position and
intraoral articulatory postures can lx documented using sophisticated techniques; this study served partly to discover the smaller subgroups that could be examined using these methods to give more detailed information on speech motor control. Protrusive and mediotrusive interferences were associated with laterally produced faulty sounds. Unexpectedly, their relations to this speech disorder were opposite. Deviation of the jaw during mouth opening was related to other misarticulations. In addition, the capacity for mandibular movement was related to speech errors, indicating that children with articulatory speech disorders were not able to open their mouth as wide as the controls but that their protrusive capacity was greater than in children with correct speech production. These findings might be due either to disturbances in peripheral factors (interferences) that assimilate orofacial structures to certain jaw movements or to poor fine-motor control of these muscles. Interestingly, certain variables reflecting motor speech skills were positively related to other misarticulations but negatively related to sounds produced too far posteriorly. In general, maturation of oral functions, such as swallowing and speech, follows a gradient from anterior to posterior (Proffit, 1986). Although immaturity of the longitudinal tongue muscles could predispose a child to sounds produced too far anteriorly, it is logical that this was not associated with sounds produced too far posteriorly. In the Finnish language, ‘r’ is a multiple trilled medioalveolar consonant and the most common posterior misarticulation is ‘r’uvularis. Sounds produced too far posteriorly were here associated with problems in coordinating muscles other than the longitudinal muscles of the tongue. Early in life, the posterior airway space is relatively small and this favours an anterior position of the tongue, which is later modified by involution of lymphoid tissue and mandibular growth, allowing more space for the tongue (Proffit and Mason, 1975; Linder-Aronson and Leighton, 1983). Interestingly, in a recent kinesiographic study, Williamson, Hall and Zwemer (1990) found that patients with CMD tended to swallow with their teeth apart and with
898
M. TELLFXVO LAW
excessive vertical and lateral mandibular movements. We did not study swallowing patterns, but our findings and those of Williamson er al. (1990) are parallel in that deviant function of the orofacial muscles seems to manifest itself during different activities. In summary, deviations in function, but not in morphology, of the orofacial muscles were associated with speech disorders. Among the 6-8-yr-old children studied, some signs of CMD, occlusal interferences, mandibular movement capacity and several variables reflecting orofacial motor skills were also related to certain disorders in speech sound production. Several orofacial dysfunctions seem to be associated with each other during growth. Longitudinal study of our sample will give information on whether orofacial dysfunctions improve with the maturation of finemotor control or whether dysfunctions become fixed with age. Acknowledgernenw-This study was supported by the Academy of Finland, the Finnish Dental Society and the North Savo Fund of the Finnish Cultural Foundation.
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(For Appendix see opposite)
899
Orofacial dysfunctions in children APPENDIX Morphology of the articulators (inspection) Tonus of lips
Width of tongue
Length of tongue
Length of soft palate
0 hypotonic 1 normal 2 hypertonic 0 decreased 1 normal 2 increased 0 decreased 1 normal 2 increased 0 adequate I short
Function of the articulators
Soft palate/ A hh/
0 adequate 1 inadequate Accurate
Tongue movements by mainly the longitudinal muscles of the tongue Tip out-in Tip side-to-side Tip up-down Coordination* of the tongue movements by mainly the longitudinal muscles Tip out-in Tip side-to-side Tip up-down Tongue movements by other than longitudinal muscles: tip round the lips Left to right Right to left Coordination of the tongue movements by other muscles: tip round the lips Left to right Right to left Raspberry-unvoiced Raspberry-coordination Raspberry-voiced DDK/te-de/ Lip movements Pucker-smile Smack Trill with lips Pucker-smile coordination Whistle
Inaccurate
Failed
0 0 0
2 2 2
0 0 0
2 2 2
0
1
0
1
2 2
*In coordination of the movements: accurate, > 5 repetitions in 10 s; inaccurate, 1-5 repetitions in 10 s; failed, no repetition:.
