Download Curve of Spee and Its Relationship with

10.5005/jp-journals-10021-1144
RESEARCH ARTICLE
Prerna Raje Batham et al
Curve of Spee and Its Relationship with
Dentoskeletal Morphology
1
Prerna Raje Batham, 2Pradeep Tandon, 3Vijay Prakash Sharma, 4Alka Singh
ABSTRACT
Objective: The influence of craniofacial morphology on the variation of the depth of curve of Spee includes multiple factors. This plays an
important role in the leveling of the curve which is required for retention of achieved results. The study evaluates relationship between the varying
depths of curve of Spee and dentoskeletal features.
Materials and methods: 120 diagnostic casts and lateral head cephalograms of selected subjects on the basis of depths of curve of Spee as
measured on the mandibular casts were selected. The subjects were divided into three Groups (Group-I- 0-2 mm, Group -II >2-4 mm and
Group-III >4 mm of curve of Spee), and further into subgroups according to sex. Cephalometric and study cast variables were measured and
subjected to statistical analysis with curve of Spee as the dependent variable and others as independent variables.
Results: SNB, APDI, OM, Md5 - MP (mm), OJ and mandibular arch length were negatively correlated and ANB, Md6 to MP, ODI, overbite and
overjet were positively correlated with depth of curve of Spee in both males and females.
Conclusion: The curve of Spee is related to various dentoskeletal variables. Thus, the determination of this relationship is useful to assess the
feasibility of leveling the curve of Spee by orthodontic treatment.
Keywords: Curve of Spee, Dentoskeletal morphology.
How to cite this article: Batham PR, Tandon P, Sharma VP, Singh A. Curve of Spee and Its Relationship with Dentoskeletal Morphology. J Ind
Orthod Soc 2013;47(3):128-134.
INTRODUCTION
A profile view of human skull reveals an upward, concave curve
in the mandibular teeth extending from molars to incisors and
corresponding downward, convex curve in the maxillary arch.
These peculiarities of the geometric arrangement of the teeth
were first described by Ferdinand Graf Von Spee1 in 1890,
using 120 skulls with abraded teeth to define a line of
occlusion, to lie on a cylinder which is tangent to the anterior
border of the condyle, the occlusal surfaces of second molar
and incisal edges of the mandibular incisors and has since been
referred to as ‘The curve of Spee’.
It has been suggested that the curve of Spee has a
biomechanical function during food processing by increasing
the crush shear ratio between the posterior teeth and the
efficiency of the occlusal forces during mastication.2,3
Andrews LF4 considered flat to slight curve of Spee to be
one of the six characteristics of normal occlusion. He also
1
Lecturer, 2Professor and Head, 3Professor and Ex-Head, 4Assistant
Professor
1
Department of Orthodontics and Dentofacial Orthopedics, Sri Auribindo
Institute of Medical Sciences, Indore, Madhya Pradesh, India
2-4
Department of Orthodontics and Dentofacial Orthopedics, Faculty of
Dental Sciences, CSM Medical University (Erstwhile KGMC), Lucknow
Uttar Pradesh, India
Corresponding Author: Prerna Raje Batham, I-43, RSS Nagar, LIG
Colony, Indore, Madhya Pradesh, India, e-mail: [email protected]
Received on: 11/4/12
Accepted after Revision: 25/8/12
128
stated that, there was a natural tendency for the curve to deepen
with time because the lower jaw sometimes grows faster and
continues for longer period than that of the upper jaw. This
causes the lower anterior teeth, which are confined by the
upper anterior teeth and lips, to be forced backward and upward,
resulting in deeper overbite and deeper curve of Spee. So, the
treatment objective should be to achieve a flat curve as an
over treatment.
Recently, the morphologic arrangement of the teeth in the
sagittal plane has been related to the deep overbite, lower
incisor proclination and lower arch circumference.5-7
Although, the influence of craniofacial morphology on the
curve of Spee has been investigated, these studies ignore the
simultaneous contribution of multiple factors to the individual
variation of the curve. These individual variations play
important role in the leveling of the curve which is an everyday
occurrence in orthodontic practices and are required for stable
results.
MATERIALS AND METHODS
The present study was conducted on pretreatment study cast
and lateral head cephalogram of 120 selected subjects on the
basis of varying depths of curve of Spee as measured on the
mandibular study cast5 with the age range of 18 to 25 years
(mean age-21.5 years). Distribution of sample is showen in
Table 1.
Subjects had a full complement of teeth with all teeth in
occlusion up to second molar. No previous orthodontic
treatment was received by any of the subjects. Mild crowding
cases were accepted but gross crowding cases were excluded.
JIOS
Curve of Spee and Its Relationship with Dentoskeletal Morphology
No anterior or lateral cross bite was present. No cast
restoration or cuspal coverage was present.
High quality orthodontic impressions for diagnostic casts
were taken by alginate impression material in the rim lock
impression trays. The lateral cephalograms of the selected
subjects were taken using the standard technique employed in
the Department of Orthodontics and Dentofacial Orthopedics,
CSM Medical University (Erstwhile KGMC). The lateral
cephalograms were traced on acetate tracing sheets 50 micron
in thickness using a sharp 4H pencil on a view box using
transilluminated light in a dark room.
MEASUREMENT OF CURVE OF
SPEE ON STUDY CAST
The depth of curve of Spee was measured as the perpendicular
distance between the deepest buccal cusp tips and a scale that
was laid on the top of the mandibular dental cast, touching the
incisal edges of the central incisors and the distal cusp tips of
the most posterior teeth in the lower arch (Fig. 1). The depth
of curve of Spee was measured with divider placed between
the deepest cusp tip and the scale. The measurements was made
on the right and left side of the mandibular cast and the mean
value of these two measurements was used as the depth of
curve of Spee.5
The cephalometric and study cast measurements used in
the study are described in Figures 2 to 7. The six skeletal
parameters, nine dentoalveolar parameters and three study cast
parameters were measured.
Measurement of Reliability
Reliability of measurements was tested by doing double
determinations of 20 cephalograms and 20 study casts
randomly selected at 15 days interval from the collected
sample by the same operator and comparison was drawn
between first and second determinations by paired ‘t’ test,
whereas testing for method errors was done by using
Dahlberg’s formula. No significant differences in initial and
repeat readings of parameters were found. Hence, good
reliability can be laid on the observations made (Table 2).
RESULTS
The data so obtained was subjected to the statistical analysis
using statistical package program STATA version 9.2.
Descriptive statistics, including the mean and standard
Fig. 1: Measurement of curve of Spee
Fig. 3: Skeletal vertical parameters
Fig. 2: Skeletal horizontal parameters
Fig. 4: Dentoalveolar horizontal parameters
The Journal of Indian Orthodontic Society, July-September 2013;47(3):128-134
129
Prerna Raje Batham et al
Fig. 5: Dentoalveolar vertical parameters
Fig. 7: Measurement of mandibular arch length (mm)
Table 1: Distribution of sample
Fig. 6: Measurement of overbite (a) and overjet (b)
deviation values were calculated for all the parameters in each
Group. Student t-test was used to determine the significant
differences between the mean and standard deviations of
various parameters in the three Groups but among the same
Group I
(flat = 0-2 mm)
(n = 40)
Group II
(normal = 2-4 mm)
(n = 40)
Group III
(deep > 4 mm)
(n = 40)
Ia—20 males
Ib—20 females
IIa—20 males
IIb—20 females
IIIa—20 males
IIIb—20 females
sex. Pearson’s correlation analysis was used to determine
correlation coefficients between the depths of the curve of
Spee and other variables used in the study. Furthermore a
multiple linear regression analysis was performed to
determine the relationship between the curve of Spee as the
dependent variable and other parameters as the independent
variables.
Descriptive statistics, including the mean and SD values,
were determined for each Spee Group and are shown in
Tables 3 and 4 for both males and females.
The correlation (Table 6) shows SNB, APDI, OM, Md5—
MP (mm), OJ and mandibular arch length were negatively
Table 2: Intraobserver comparison of mean ± SD of values of parameters
S. no.
Parameters
Mean ± SD values of
initial readings
Mean ± SD values
of repeat readings
t-value
p-value
Skeletal horizontal
1.
SNB (degree)
2.
ANB (degree)
3.
APDI (degree)
80.40 ± 1.86
2.84 ± 1.32
85.40 ± 2.84
80.30 ± 1.89
2.86 ± 1.73
85.03 ± 4.28
2.39
4.61
5.75
0.95
0.35
0.18
Skeletal vertical
4.
ODI (degree)
76.05 ± 5.99
76.24 ± 6.59
2.23
0.18
Dentoalveolar horizontal
5.
Md6 to MP (degree)
6.
Md7 to MP (degree)
7.
OM (mm)
83.20 ± 5.98
94.45 ± 5.39
44.40 ± 3.32
83.74 ± 3.17
94.20 ± 4.91
44.20 ± 4.09
0.82
0.15
1.58
0.41
0.87
0.12
Dentoalveolar vertical
8.
Md5 to MP (mm)
9.
Md6 to MP (mm)
10.
OJ (mm)
34.45 ± 2.24
33.95 ± 2.37
41.45 ± 4.03
34.35 ± 4.95
33.87 ± 3.15
41.35 ± 3.37
1.49
1.23
2.64
0.14
0.23
0.16
Study cast
11.
Overbite (mm)
12.
Overjet (mm)
13.
Md. arch length (mm)
3.48 ± 1.44
2.50 ± 0.83
39.50 ± 2.03
3.57 ± 1.32
2.72 ± 1.47
39.32 ± 2.89
3.68
3.70
4.39
0.22
0.34
0.27
p-value: >0.05: nonsignificant; <0.05: just significant; <0.01: moderately significant; <0.001: highly significant
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Curve of Spee and Its Relationship with Dentoskeletal Morphology
Table 3: Comparison of mean and standard deviation values for Groups Ia, IIa and IIIa (males)
S. no.
Parameters
Group Ia flat
Mean ± SD
Group IIa normal
Mean ± SD
Group IIIa deep
Mean ± SD
Ia vs IIa
p-value
Ia vs IIIa
IIa vs IIIa
Skeletal horizontal
1.
SNB
2.
ANB
3.
APDI
82.75 ± 3.58
2.60 ± 1.27
85.85 ± 3.53
79.85 ± 2.43
3.80 ± 1.24
83.15 ± 2.39
78.10 ± 3.57
5.55 ± 1.57
77.95 ± 4.94
<0.01**
<0.01**
<0.01**
<0.001***
<0.001***
<0.001***
0.07
<0.001***
<0.001***
Skeletal vertical
4.
ODI
77.35 ± 5.87
81.30 ± 4.62
83.90 ± 8.93
<0.05*
<0.01**
0.25
Dentoalveolar horizontal
5.
Md6 to MP
6.
Md7 to MP
7.
OM (mm)
82.70 ± 6.02
92.60 ± 7.42
47.05 ± 3.92
84.95 ± 5.27
95.05 ± 6.17
46.80 ± 3.33
85.85 ± 6.27
95.20 ± 3.96
43.05 ± 3.78
0.51
0.18
0.82
<0.05*
<0.05*
<0.01**
0.94
0.92
<0.01**
Dentoalveolar vertical
8.
Md5 to MP
9.
Md6 to MP
10.
OJ (mm)
39.20 ± 2.35
37.75 ± 2.38
47.05 ± 4.96
38.00 ± 3.09
37.00 ± 3.36
42.60 ± 4.38
36.95 ± 2.99
36.15 ± 2.74
42.55 ± 5.14
0.17
0.42
<0.01**
<0.05*
0.18
<0.05*
0.28
0.38
0.97
Study cast
11.
12.
13.
2.88 ± 1.37
2.20 ± 0.77
40.50 ± 2.09
3.73 ± 1.19
3.25 ± 0.82
38.30 ± 2.20
6.78 ± 2.67
6.65 ± 4.47
37.40 ± 1.76
<0.05*
<0.001***
<0.01**
<0.001***
<0.001***
<0.001***
<0.001***
<0.01**
0.16
Overbite
Overjet
Md. arch length
p-value : >0.05: nonsignificant; *<0.05: just significant; **<0.01: moderately significant; ***<0.001: highly significant
Table 4: Comparison of mean and standard deviation for Groups Ib, IIb and IIIb (females)
S. no.
Parameters
Skeletal horizontal
1.
SNB
2.
ANB
3.
APDI
Skeletal vertical
4.
ODI
Dentoalveolar horizontal
5.
Md6 to MP
6.
Md7 to MP
7.
OM (mm)
Dentoalveolar vertical
8.
Md5 to MP
9.
Md6 to MP
10.
OJ (mm)
Study cast
11.
Overbite
12.
Overjet
13.
Md. arch length
Group Ib flat
(0-2 mm)
Mean ± SD
Group IIb
normal (2-4 mm)
Mean ± SD
Group IIIb
deep (<4 mm)
Mean ± SD
p-value
Ib vs IIb
Ib vs IIIb
IIb vs IIIb
80.45 ± 1.76
2.80 ± 1.32
85.40 ± 2.84
80.40 ± 2.78
3.20 ± 1.32
84.65 ± 3.97
78.25 ± 3.61
5.05 ± 1.73
77.53 ± 5.28
0.57
0.34
0.49
<0.05*
<0.001***
<0.001***
<0.05*
<0.001***
<0.001***
76.05 ± 5.99
77.20 ± 5.75
80.50 ± 6.59
0.53
<0.05*
0.10
83.20 ± 5.98
94.20 ± 4.91
44.40 ± 3.32
84.80 ± 6.27
94.45 ± 5.39
42.70 ± 4.09
86.55 ± 5.17
94.90 ± 5.32
42.25 ± 5.09
0.06
0.79
0.11
<0.05*
0.87
0.12
0.34
0.67
0.76
34.45 ± 2.24
33.95 ± 2.37
41.45 ± 4.03
34.25 ± 2.55
33.80 ± 2.09
39.55 ± 4.27
33.10 ± 3.35
32.90 ± 2.51
38.70 ± 2.32
0.79
0.83
0.16
0.14
0.23
<0.05*
0.23
0.18
0.44
3.48 ± 1.44
2.50 ± 0.83
39.50 ± 2.03
3.90 ± 1.05
2.80 ± 8.6
38.30 ± 1.41
6.28 ± 2.48
5.38 ± 3.57
36.35 ± 2.89
0.26
0.26
<0.05*
<0.001***
<0.001***
<0.001***
<0.001***
<0.001***
<0.001***
p-value : >0.05: nonsignificant; *<0.05: just significant; **<0.01: moderately significant; ***<0.001: highly significant
correlated and ANB, Md6 to MP, ODI, overbite and overjet
were positively correlated with depth of curve of Spee in both
males and females.
Multiple regression analysis was performed to see the
linear dependence of various studied parameters on curve of
Spee. Corresponding -coefficient and their 95% confidence
interval (CI) are described in Table 5.
Regression analysis shows that there was highly significant
correlation between curve of Spee and ANB, overbite, mandibular archlength (<0.001***), where as for OJ (mm) it was
moderately significant (<0.01**) and for Md5 to MP (mm)
and Md6 to MP (degree) was just significant (<0.05*). These
parameters explained 66% of the total variation of the curve of
Spee.
Table 5: Multiple regression analysis
Parameters
-coefficient (95% CI)
ANB
Overbite
Mandibular archlength
OJ (mm)
Md5-MP (mm)
Md6-MP (degree)
Constant
0.250 (0.17, 0.33)
<0.001***
0.189 (0.12, 0.26)
<0.001***
–0.119 (–0.18, –0.06) <0.001***
–0.044 (–0.07, –0.01) <0.01** 0.66
–0.043 (–0.10, 0.00)
<0.05*
0.041 ( 0.01, 0.11)
<0.05*
10.547 (6.16, 14.94)
0.000
p-value
R2 change
DISCUSSION
The assessment of relationship of curve of Spee with the
dentoskeletal morphology is essential to understand the
The Journal of Indian Orthodontic Society, July-September 2013;47(3):128-134
131
Prerna Raje Batham et al
Table 6: Correlation of depth of curve of Spee with different parameters used in the study in male and female samples
S.no.
Parameters
Males
‘R’
Skeletal horizontal
1.
2.
3.
Skeletal vertical
4.
Dentoalveolar horizontal
5.
6.
7.
Dentoalveolar vertical
8.
9.
10.
Study cast
11.
12.
13.
SNB
ANB
APDI
ODI
– 0.54
0.66
– 0.69
0.35
Females
‘p’
<0.001***
<0.001***
<0.001***
<0.01**
‘R’
– 0.30
0.55
– 0.59
‘p’
<0.05*
<0.001***
<0.001***
0.31
<0.05*
Md6 to MP
Md7 to MP
OM (mm)
0.34
0.09
– 0.46
<0.05*
0.08
<0.001***
0.33
0.06
– 0.20
<0.05*
0.67
0.12
Md5 to MP
Md6 to MP
OJ (mm)
– 0.32
– 0.23
– 0.40
<0.05*
0.08
<0.05*
– 0.21
– 0.17
– 0.34
0.09
0.19
<0.01**
Overbite
Overjet
Mandibular arch length
0.76
0.71
– 0.56
<0.001***
<0.001***
<0.001***
0.61
0.51
– 0.54
<0.001***
<0.001***
<0.001***
p-value : NS: nonsignificant; *<0.05: just significant; **<0.01: moderately significant; ***<0.001: highly significant
influence of multiple factors that leads to variation in the
depth of the curve. It has been suggested that the mandibular
sagittal and vertical position relative to the cranium is related
to the curve of Spee, which is present in various forms in
mammals (Farella et al).8 In humans, an increased curve of
Spee is often seen in brachycephalic facial patterns (Wylie9
and Bjork)10 and associated with short mandibular bodies
(Salem OH et al).11
Although, leveling of the curve of Spee is an everyday
occurrence in orthodontic practices, little research has been
done to examine the relationship of the curve of Spee and the
multiple factors causing variation in its depth, which may be
useful to assess the feasibility of leveling the curve of Spee
by orthodontic treatment.
The measurement of curve of Spee was done and the
average of the distance on right and left side was taken as the
depth of curve of Spee (Nanda SK,12 Dale J,13 and Baydas
et al).5 This method of assessment of curve of Spee was easy
to perform and lacked any magnificational and projectional
errors. Other authors like Baldridge6 used the perpendicular
distances on both sides, Sondhi et al14 used the sum of the
perpendiculars, Bishara et al15 used the average of the sum of
the perpendicular distances to each cusp tip and Braun et al7
and Braun and Schmidt16 used the sum of the maximum depth
on both sides.
The age group was in the range of 18 to 25 years to omit
any effect of growth on the curve of Spee since, the depth
remained relatively constant during adulthood as compared to
the flat curve in decidous dentition and maximum deepening
during adolescent dentition (Marshall et al).17 This was also
supported by Farella et al8 who said that homogenous dental
wear could be the reason for maintenance of curve of Spee in
adulthood.
132
The parameters used were 10 cephalometric and 3 study
cast, of which cephalometric parameters were further divided
into skeletal and dentoalveolar. Since the curve of Spee was
significantly influenced by sagittal and vertical craniofacial
morphology as suggested by Farella et al,8 the cephalometric
parameters were further divided into four skeletal horizontal,
two skeletal vertical, five dentoalveolar horizontal and four
dentoalveolar vertical parameters.
The findings suggested that the depth curve of Spee was
influenced by the position of the mandible with respect to the
anterior cranial base, i.e. SNB. The negative correlation value
suggested that more the mandible was positioned anteriorly
(large SNB angle) the depth of curve of Spee was less, and as
the SNB angle decreased from Groups I to III, depth also
increased in both males and females. This was supported by
studies done by Farella et al8 and Cheon et al.18
It was found that the subjects with higher maxillomandibular discrepancies tend to have deeper curve of Spee.
The value of ANB showed positive correlation with the depth
of curve of Spee, i.e. was less in subjects with small value of
ANB angle (suggesting Class I skeletal pattern) and as the value
of ANB angle increased the depth of curve of Spee also
increased (the Class-II skeletal pattern) also supported by
Cheon et al18 and Orthlieb JD19 who suggested that the depth
of curve of Spee was lesser in those with Class III malocclusions than in Class II malocclusions.
The curve of Spee was influenced by the skeletal pattern
of the subjects as suggested by the values of APDI, that is
smaller the APDI value in relation to the normal mean greater
was the probability of distocclusion thus suggesting Class II
skeletal pattern and deep curve of Spee. This finding was similar
to a study conducted by Cheon et al.18
JIOS
Curve of Spee and Its Relationship with Dentoskeletal Morphology
Overbite depth indicator was given by Kim,20 suggesting
that lower the ODI value greater the chance of there being
openbite or tendency toward an openbite. The overbite and
tendency toward deepbite were found to increase as the ODI
value increased. In the present study the findings suggested
that as the depth of curve of Spee increases from Groups I
to II the tendency for deep bite in the subjects also increases,
this correlates with the increase value of overbite in Group III
as compared to Group I. Similar findings were also reported
by Trauten et al,21 who reported negative curve of Spee in
openbite cases and deep curve of Spee in deep bite cases. The
positive correlation value for both males and females suggested
that the value of ODI increases with increase in the depth of
curve of Spee. The higher value of ODI among Group-III
signifies deep bite and tendency toward deep bite in deep curve
of Spee Groups for both males and females Cheon et al.18
Md6 to MP and Md7 to MP angles were considered to
asses the possible relation between the axial inclination of
the mandibular molars and the depth of curve of Spee. The
mean values were found to be increased with increase in curve
of Spee depth suggesting that the mesial inclination of the
molars were increasing as the depth of the curve of Spee was
increased and the difference was found to be statistically
significant. Similar findings were also reported by Shannon
and Nanda22 and Lie F,23 who suggested that deepening of curve
of Spee can occur as the axial inclination of the teeth
increases. Osborn24 also showed similar findings and related
forward tilting of molars to the inclination of masseter muscle
thus increasing crush- shear ratio, also supported by Hemley25
and Thompson and Strang.26
OM (mm) was the distance measured from the most
posterior point of the dentition on the occlusal plane (point
‘M’) to the point of intersection (point ‘O’) of a line
perpendicular from the superior most point on the condyle
(Farella et al).8 It is the linear distance signifying the horizontal
positioning of the dentition with respect to the condyle. The
value of OM (mm) was found to be decreasing from Groups I
to III suggesting that the samples in which the dentition was
more posteriorly positioned with respect to the condyle, i.e.
smaller the value of ‘OM’ greater the depth of curve of Spee.
The finding of present study supported the hypothesis by Farella
et al8 that the position of dentition in the mandibular arch in
relation to the condyle influences the shape of the curve of
Spee.
The difference of the mean value for Md5 to MP (mm)
was just significant (<0.05) for Groups I vs III in male samples.
Rest all the Groups showed nonsignificant correlations. This
was due to greater infraposition of the mandibular second
premolar with relation to mandibular plane in Group III as
compared to other Groups leading to deep curve of Spee. In
the present study the deepest point of the curve of Spee was
found to be the cusp tip of second premolar region in maximum
number of samples. Koyama27 and Lie F23 also supported this
finding and suggested that the deepest point of the curve is the
cusp tip of mandibular second premolar. Shannon and Nanda,22
reported in their study that there is lack of correlation between
the depth of curve of Spee and perpendicular distance of
mandibular plane to the molar cusp tip same was found in this
study.
OJ signifies the vertical positioning of the lower dentition
with respect to the condyle. It was measured as the perpendicular distance between the superior most point on the condylar
head (point ‘J’) and the point of intersection of this
perpendicular to the occlusal plane (point ‘O’). In this study
the mean value for OJ (mm) was found to be decreasing from
Groups I to III, this finding suggested that the dentition had
moved upward with respect to the condyle in deep curve of
Spee Groups for both males and females. The finding signifies
that as the vertical distance between the lower dentition and
the condyle had decreased as the depth of curve of Spee was
increased. The finding of the study was supported by the
findings of Farella et al.8
The mean value for overbite and overjet was found to be
increased from Groups I to III in both males and females. This
suggested that when the anterior teeth have no vertical stop,
their continued eruption leads to deepening of anterior aspect
of the curve. This was supported by findings of Shannon and
Nanda.22 The positive correlation coefficient value also proved
as the overbite increases depth of curve of Spee also increases.
These findings were supported by studies done by Alqubandi28
and Lie F.23 These finding showed that the overbite measurements in the deep Spee Group were significantly larger than
in the moderate and flat Spee Groups. The most pronounced
differences for overbite were found between the flat and deep
Spee Groups as supported by studies of Kuitert,29 Baydas et al5
and Cheon et al.18 The statistically significant beta-correlation
coefficients between the depth of curve of Spee and overbite
(0.189) confirmed this result. These finding were supported
by Trauten et al21 and Orthlieb,19 they showed that there is
negative curve of Spee in open bite cases and as the curve of
Spee deepens the overbite also deepens.
The value for mandibular arch length was found to be
decreased from Groups I to III in both males and Females.
The possible explanation for these finding could be that as the
curve of Spee is deepening from Groups I to III the mandibular
incisors are becoming more uprighted and thus the
perpendicular distance from the midpoint between the incisal
edges and a line passing through the distobuccal cusp tips was
becoming shorter, thus decreasing the mandibular arch length.
These findings were supported by De Praeter et al,30 who said
that more pronounce curve could be considered as
compensation for lack of arch circumference.
In similar findings Braun et al7 and Al Qubandi,28 said that
deep curve of Spee is associated with smaller mandibular arch
length and there is increase in the arch length as the curve of
Spee is leveled.
The purpose of this cross-sectional study was to find out
the correlation between the dentoskeletal morphology and the
depth of curve of Spee. This study has unmasked the
dentoskeletal morphologic features associated with the flat,
The Journal of Indian Orthodontic Society, July-September 2013;47(3):128-134
133
Prerna Raje Batham et al
moderate and deep curve of Spee. Subjects with deep curve of
Spee had shown to have sagittal discrepancies, posteriorly and
superiorly positioned dentition in the mandible suggesting
Class II pattern. Dentally these subjects showed deep overbites,
elevated anterior teeth, depressed premolars and mesially
inclined molars.
CONCLUSION
Following conclusions were drawn on the basis of the findings
of this study:
1. The depth of curve of Spee was greatly influenced by
sagittal maxillomandibular discrepancies. The values for
parameters SNB, ANB and APDI suggested that the
mandible was located more posteriorly in deep curve of
Spee Group.
2. The variation in the depth of curve of Spee significantly
influences the overbite, overjet and the inclination of
mandibular first molar.
3. The height of mandibular second premolar, position of
mandibular dentition with respect to the condyle and
mandibular arch length showed significant decrease with
increase in the depth of curve of Spee.
4. The correlation coefficients obtained from the study
suggested that the depth of curve of Spee was positively
correlated with ANB, ODI, Md6 to MP (degree), overbite
and overjet that is, as the value of above mentioned
parameters increases as the depth of curve of Spee
increases and negatively correlated with SNB, APDI, Md5
to MP (mm) and mandibular arch length that is, with
decrease in the depth of curve of Spee, the value of above
mentioned parameters decreases.
5. The multiple regression analysis showed that the curve of
Spee was significantly influenced by ANB, overbite,
mandibular arch length, vertical positioning of dentition
with respect to condyle (OJ), Md5 to MP (mm) and Md6
to MP (degree). These parameters explained 66% of the
total variation of the curve of Spee in the regression model.
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