European Journal of Orthodontics 12 (1990) 408-413
I 1990 European Orthodontic Society
Relationship between craniofacial and condyle path asymmetry in unilateral cross-bite patients Pertti Pirttiniemi, Tuomo Kantomaa, and Pia Lahtela Institute of Dentistry, University of Oulu, Oulu, Finland
Introduction
Mild craniofacial asymmetry has been shown to be common in human beings (Letzer and Kronman, 1967; Cook, 1980), the left side of the face being slightly larger than the right side in general (Vig and Hewitt, 1975). Dental midline asymmetry is also common in the normal population, and the midline of the lower dental arch is found to deviate to the right more often than to the left (Svanholt and Solow, 1977). The slope of the condyle path has been found clinically to vary greatly between individuals (Ricketts, 1950) and slight asymmetry is common (Isaacson, 1959). However, reports on dentofacial asymmetry or transverse malocclusions are few and little is known of the associations between these, although it has been noticed that the face tends to be more asymmetric in association with asymmetric malocclusion in particular (Alavi el al., 1988). As the shape of the articulating surface of the TMJ has recently been shown to be an important element in the development of the mandible
(Kantomaa, 1988, 1989), the aim of this study was to examine the degree and direction of asymmetry in the condyle path and its correlations with facial and dental midline asymmetry in patients with treated or untreated unilateral cross-bite.
Subjects and methods
The subjects were 22 patients, 16 female and 6 male, aged from 9 to 50 years. Nine patients had a history of treated unilateral cross-bite, the mean age of this group being 11.1 years (aged from 9 to 13 years). A removable or fixed expansion appliance had been used at an age of 5-8 years. Thirteen patients had untreated unilateral cross-bite, the mean age being 23.4 years (aged from 10 to 50 years). The clinical examinations were performed by two orthodontists. Standard PA roentgenograms were taken in a cephalostat. The lines and angles used are shown in Fig. 1. All the angles
Downloaded from http://ejo.oxfordjournals.org/ at Université Laval on June 30, 2014
SUMMARY The aim of this work was to examine the degree and direction of asymmetry in the condyle path, and its associations with facial and dental midline asymmetry in patients with treated and untreated unilateral cross-bite. The subjects were 22 patients, 16 female and 6 male, aged from 9 to 50 years. Nine patients had a history of treated unilateral cross-bite, the mean age of this group being 11.1 years. The children had been treated with removable or fixed expansion appliances at an age of 5-8 years. Thirteen patients had untreated unilateral cross-bite, their mean age being 23.4 years. The clinical examinations were performed by two orthodontists and standard PA roentgenograms were taken in a cephalostat. The condyle path was recorded from the inversion of a face bow fixed rigidly on the anterior mandibular teeth, the positions of the bow being first recorded with the teeth in maximal intercuspation and then in protrusion with the midline unchanged. The condyle path was found to be asymmetric in both the treated and untreated lateral crossbite groups and to be steeper on the side of the diagnosed or treated cross-bite. The degree of asymmetry was found to be twice as great in the untreated as in the treated group. The facial asymmetry parameters describing the position of the mandible showed the strongest correlation with condyle path asymmetry. The results stress the importance of early treatment of lateral crossbites.
409
CONDYLE PATH ASYMMETRY WITH CROSS-BITE
Figure 1 Linear variables, lines, and angles on standard P.A. roentgenograms. The vertical reference line goes through the lowest midpoint of the Crista Galli and is perpendicular to the orbital plane. a.n.s., Distance between the anterior nasal spine and the vertical reference line in millimetres, u.inc, Distance between the upper incisal midline and the vertical reference line in millimetres. Line, Distance between the lower incisal midline and the vertical reference line in millimetres. Line.-u.inc, Relationship of the lower incisal midline to the upper incisal midline. me, Distance between the menton and the vertical reference line in millimetres. Occl PL, tangent to the lower most tips of the cusps of the molars of the maxilla. Mand PL, plane through the left and right antegonial notches. Orb PL, tangent to the extreme superior orbital margins.
were traced twice to test the intra-examiner methodological error by the formula
where d is the difference between repeated measurements. Asymmetry in the condyle path was recorded from inversion of a face bow cemented rigidly to the anterior mandibular teeth after mechanical fixation (Fig. 2). The end of the outer bow was adjusted so that it was located in the TMJ area.
Results
The means, standard deviations, and intra-examiner errors are presented in Table 1. The condyle path was found to be asymmetric in both the treated and non-treated lateral cross-bite groups (Table 2). Most of the patients (20 out of 22) showed asymmetry in the descent of the condyle which was greater than 0.25 degrees in relation to the interpupillary axis in frontal projection (Table 3). When the direction of asymmetry was studied with respect to the left side and right side cross-bites, the condyle path was found to be steeper on the side of the treated or untreated cross-bite (Tables 3 and 4). Asymmetry in the condyle path was twice as great in the untreated as in the treated patients (Table 2). In the clinical examination three of the patients, two in the treated cross-bite group and one in the untreated group were found to have asymmetric slides from maximal intercuspal position to retruded position. The parameters of facial and dental midline asymmetry were studied in relation to condyle path asymmetry. The parameters describing the position of the mandible showed the strongest correlation with condyle path asymmetry. If the condyle path was steeper on the right, the mandible was shifted further to the right and the
Downloaded from http://ejo.oxfordjournals.org/ at Université Laval on June 30, 2014
The patient was first photographed in frontal and lateral projection with the teeth in maximal intercuspation. The upper dental midline was marked on the cemented face bow with a sharp pencil. After this the mandible was protruded, with the midlines unchanged, and a new photograph in the frontal plane was taken. The constancy of the dental midlines during the movement to protrusion was first established by checking that the marked midlines exactly coincided after the protrusion. The angular inversion of the bicondylar path in the frontal plane could then be measured from the change in the two frontal photographs, in which the interpupillary axis served as a reference line (Fig. 3). The mean value of two measurements was used in the analysis to reduce random error, as has been suggested (Houston, 1983). The intra-examiner methodological error was tested with the same formula as above. The statistical analysis included Student's Mest, Spearman's correlation, Fischer's exact test, and Mann-Whitney's [/-test.
410
(b)
Figure 2 (a) The face bow cemented on patients anterior lower teeth. Teeth are in maximal intercuspation. (b) The mandible is brought to protrusion with midline unchanged.
lower border of the mandible was rotated clockwise in the frontal projection. The direction of asymmetry was found to be the same where the parameters of the maxilla were concerned, but the correlation was weaker (Table 5). Discussion A relationship has been described between the height of the eminence and the shape of the articulating surface of the glenoid fossa (Ingervall, 1974), Isaacson (1959) and Ingervall (1974) have suggested that the condyle path is closely associated with the shape of the articulating surface of the glenoid fossa and that the functional anatomy of the glenoid fossa can be accurately studied from the movement of the mandible. As the new method used here to record asymmetry between the right and left side of the condylar path appears to be accurate and simple to use, it may be recommended for measuring
asymmetry in the slope of the articulating surface of the glenoid fossa in clinical practice. The adaptive nature of the glenoid fossa has been shown in various descriptions of the functional anatomy of the TMJ after changes in occlusion and the position of the mandible (Breitner, 1940; Hinton, 1981; Hinton and MacNamara, 1984;Woodsideef a/., 1987). Although the mandible may not remain in the asymmetric maximal intercuspal position long enough to affect craniofacial growth, Troelstrup and Moller (1970), and Ingervall and Thilander (1975) have observed that temporal muscle activity is also asymmetric in postural positions, which indicates that the mandible may be asymmetrically positioned most of the time. The fact that only one of 13 untreated lateral cross-bite patients showed a clinically detectable asymmetric slide from intercuspal position to retruded position may be due to adaptation, as the mean age of this group was higher than the average in
Downloaded from http://ejo.oxfordjournals.org/ at Université Laval on June 30, 2014
(a)
P. PIRTTINIEMI ET AL.
411
CONDYLE PATH ASYMMETRY WITH CROSS-BITE
Table 3 Eminence height asymmetry studied in a group of treated or untreated unilateral cross-bite patients with measured asymmetry > 0.25 degrees in the frontal plane (w = 20). Number of patients Cross-bite Corrected cross-bite
R L R L
Eminence higher on the right
Eminence higher on the left
9 0 6 0
0 (0%) 3(25%) •* 0 (0%) 2(25%) *
(75%) (0%) (75%) (0%)
** />
I 1990 European Orthodontic Society
Relationship between craniofacial and condyle path asymmetry in unilateral cross-bite patients Pertti Pirttiniemi, Tuomo Kantomaa, and Pia Lahtela Institute of Dentistry, University of Oulu, Oulu, Finland
Introduction
Mild craniofacial asymmetry has been shown to be common in human beings (Letzer and Kronman, 1967; Cook, 1980), the left side of the face being slightly larger than the right side in general (Vig and Hewitt, 1975). Dental midline asymmetry is also common in the normal population, and the midline of the lower dental arch is found to deviate to the right more often than to the left (Svanholt and Solow, 1977). The slope of the condyle path has been found clinically to vary greatly between individuals (Ricketts, 1950) and slight asymmetry is common (Isaacson, 1959). However, reports on dentofacial asymmetry or transverse malocclusions are few and little is known of the associations between these, although it has been noticed that the face tends to be more asymmetric in association with asymmetric malocclusion in particular (Alavi el al., 1988). As the shape of the articulating surface of the TMJ has recently been shown to be an important element in the development of the mandible
(Kantomaa, 1988, 1989), the aim of this study was to examine the degree and direction of asymmetry in the condyle path and its correlations with facial and dental midline asymmetry in patients with treated or untreated unilateral cross-bite.
Subjects and methods
The subjects were 22 patients, 16 female and 6 male, aged from 9 to 50 years. Nine patients had a history of treated unilateral cross-bite, the mean age of this group being 11.1 years (aged from 9 to 13 years). A removable or fixed expansion appliance had been used at an age of 5-8 years. Thirteen patients had untreated unilateral cross-bite, the mean age being 23.4 years (aged from 10 to 50 years). The clinical examinations were performed by two orthodontists. Standard PA roentgenograms were taken in a cephalostat. The lines and angles used are shown in Fig. 1. All the angles
Downloaded from http://ejo.oxfordjournals.org/ at Université Laval on June 30, 2014
SUMMARY The aim of this work was to examine the degree and direction of asymmetry in the condyle path, and its associations with facial and dental midline asymmetry in patients with treated and untreated unilateral cross-bite. The subjects were 22 patients, 16 female and 6 male, aged from 9 to 50 years. Nine patients had a history of treated unilateral cross-bite, the mean age of this group being 11.1 years. The children had been treated with removable or fixed expansion appliances at an age of 5-8 years. Thirteen patients had untreated unilateral cross-bite, their mean age being 23.4 years. The clinical examinations were performed by two orthodontists and standard PA roentgenograms were taken in a cephalostat. The condyle path was recorded from the inversion of a face bow fixed rigidly on the anterior mandibular teeth, the positions of the bow being first recorded with the teeth in maximal intercuspation and then in protrusion with the midline unchanged. The condyle path was found to be asymmetric in both the treated and untreated lateral crossbite groups and to be steeper on the side of the diagnosed or treated cross-bite. The degree of asymmetry was found to be twice as great in the untreated as in the treated group. The facial asymmetry parameters describing the position of the mandible showed the strongest correlation with condyle path asymmetry. The results stress the importance of early treatment of lateral crossbites.
409
CONDYLE PATH ASYMMETRY WITH CROSS-BITE
Figure 1 Linear variables, lines, and angles on standard P.A. roentgenograms. The vertical reference line goes through the lowest midpoint of the Crista Galli and is perpendicular to the orbital plane. a.n.s., Distance between the anterior nasal spine and the vertical reference line in millimetres, u.inc, Distance between the upper incisal midline and the vertical reference line in millimetres. Line, Distance between the lower incisal midline and the vertical reference line in millimetres. Line.-u.inc, Relationship of the lower incisal midline to the upper incisal midline. me, Distance between the menton and the vertical reference line in millimetres. Occl PL, tangent to the lower most tips of the cusps of the molars of the maxilla. Mand PL, plane through the left and right antegonial notches. Orb PL, tangent to the extreme superior orbital margins.
were traced twice to test the intra-examiner methodological error by the formula
where d is the difference between repeated measurements. Asymmetry in the condyle path was recorded from inversion of a face bow cemented rigidly to the anterior mandibular teeth after mechanical fixation (Fig. 2). The end of the outer bow was adjusted so that it was located in the TMJ area.
Results
The means, standard deviations, and intra-examiner errors are presented in Table 1. The condyle path was found to be asymmetric in both the treated and non-treated lateral cross-bite groups (Table 2). Most of the patients (20 out of 22) showed asymmetry in the descent of the condyle which was greater than 0.25 degrees in relation to the interpupillary axis in frontal projection (Table 3). When the direction of asymmetry was studied with respect to the left side and right side cross-bites, the condyle path was found to be steeper on the side of the treated or untreated cross-bite (Tables 3 and 4). Asymmetry in the condyle path was twice as great in the untreated as in the treated patients (Table 2). In the clinical examination three of the patients, two in the treated cross-bite group and one in the untreated group were found to have asymmetric slides from maximal intercuspal position to retruded position. The parameters of facial and dental midline asymmetry were studied in relation to condyle path asymmetry. The parameters describing the position of the mandible showed the strongest correlation with condyle path asymmetry. If the condyle path was steeper on the right, the mandible was shifted further to the right and the
Downloaded from http://ejo.oxfordjournals.org/ at Université Laval on June 30, 2014
The patient was first photographed in frontal and lateral projection with the teeth in maximal intercuspation. The upper dental midline was marked on the cemented face bow with a sharp pencil. After this the mandible was protruded, with the midlines unchanged, and a new photograph in the frontal plane was taken. The constancy of the dental midlines during the movement to protrusion was first established by checking that the marked midlines exactly coincided after the protrusion. The angular inversion of the bicondylar path in the frontal plane could then be measured from the change in the two frontal photographs, in which the interpupillary axis served as a reference line (Fig. 3). The mean value of two measurements was used in the analysis to reduce random error, as has been suggested (Houston, 1983). The intra-examiner methodological error was tested with the same formula as above. The statistical analysis included Student's Mest, Spearman's correlation, Fischer's exact test, and Mann-Whitney's [/-test.
410
(b)
Figure 2 (a) The face bow cemented on patients anterior lower teeth. Teeth are in maximal intercuspation. (b) The mandible is brought to protrusion with midline unchanged.
lower border of the mandible was rotated clockwise in the frontal projection. The direction of asymmetry was found to be the same where the parameters of the maxilla were concerned, but the correlation was weaker (Table 5). Discussion A relationship has been described between the height of the eminence and the shape of the articulating surface of the glenoid fossa (Ingervall, 1974), Isaacson (1959) and Ingervall (1974) have suggested that the condyle path is closely associated with the shape of the articulating surface of the glenoid fossa and that the functional anatomy of the glenoid fossa can be accurately studied from the movement of the mandible. As the new method used here to record asymmetry between the right and left side of the condylar path appears to be accurate and simple to use, it may be recommended for measuring
asymmetry in the slope of the articulating surface of the glenoid fossa in clinical practice. The adaptive nature of the glenoid fossa has been shown in various descriptions of the functional anatomy of the TMJ after changes in occlusion and the position of the mandible (Breitner, 1940; Hinton, 1981; Hinton and MacNamara, 1984;Woodsideef a/., 1987). Although the mandible may not remain in the asymmetric maximal intercuspal position long enough to affect craniofacial growth, Troelstrup and Moller (1970), and Ingervall and Thilander (1975) have observed that temporal muscle activity is also asymmetric in postural positions, which indicates that the mandible may be asymmetrically positioned most of the time. The fact that only one of 13 untreated lateral cross-bite patients showed a clinically detectable asymmetric slide from intercuspal position to retruded position may be due to adaptation, as the mean age of this group was higher than the average in
Downloaded from http://ejo.oxfordjournals.org/ at Université Laval on June 30, 2014
(a)
P. PIRTTINIEMI ET AL.
411
CONDYLE PATH ASYMMETRY WITH CROSS-BITE
Table 3 Eminence height asymmetry studied in a group of treated or untreated unilateral cross-bite patients with measured asymmetry > 0.25 degrees in the frontal plane (w = 20). Number of patients Cross-bite Corrected cross-bite
R L R L
Eminence higher on the right
Eminence higher on the left
9 0 6 0
0 (0%) 3(25%) •* 0 (0%) 2(25%) *
(75%) (0%) (75%) (0%)
** />
