Download correlation between curve of spee and vertical eruption of teeth

Original Article
CORRELATION BETWEEN CURVE OF SPEE AND VERTICAL
ERUPTION OF TEETH AMONG VARIOUS GROUPS OF
MALOCCLUSION
TAYYABA BIBI
AHSAN MAHMOOD SHAH
1
2
ABSTRACT
The aim of this study was to determine the depth of curve of Spee (COS) in different types of malocclusion and find a relationship between depth of COS and vertical eruption of anterior or posterior
teeth.
The study was conducted at Department of Orthodontics, Khyber College of Dentistry using the
record of 120 patients in the form of lateral cephalograms and dental casts. The patients were divided
into 4 equal groups (30 each) based on dental malocclusion as class I, class II div 1, class II div2 and
class III. The depth of COS was measured for each group using a flat plane touching the incisors
anteriorly and distal marginal ridges of posterior teeth on mandibular cast. On lateral cephalograms,
perpendicular distances from the incisal tip of mandibular central incisor (L1-MP), the deepest point
of COS (S-MP) and distobuccal cusp tip of mandibular second molar (L7-MP) to mandibualr plane
(MP) were measured and proportioned as L1-MP/S-MP and L7-MP/S-MP. Pearson correlation was
used to assess the relationship between COS and L1-MP/S-MP and L7-MP/S-MP.
The second premolar cusp tip was the deepest point of COS in all groups with the maximum depth
of 2.80 ± 0.417mm in Class II div2 and minimum depth of 1.40 ± 0.693mm in Class I malocclusion.
Significant positive correlations were found between depth of COS and LI-MP/S-MP for Class I
(r =0.670) and Class III (r =0.267) groups while L7-MP/S-MP was significant for Class II div 2
(r =0.235).
It was concluded that depth of COS is affected by vertical eruption of anterior teeth in class I and
Class III malocclusion while posterior teeth eruption significantly contributed in Class II div 2.
Key Words: Curve of Spee, malocclusion, mandibular plane, vertical eruption, teeth.
INTRODUCTION
Lateral view of the human dentition reveals an
anatomic plane which is generally concave with the
concavity facing upward.1 In 1890 Ferdinand Graf Von
Spee2 defined a line of occlusion by using skulls with
abraded teeth which is now termed as curve of Spee
(COS). The curve of Spee is a line on a cylinder that is
tangent to the anterior border of the condyle, the occlusal surface of the mandibular second molar and the
incisal edges of the mandibular incisors. Clinically the
distal marginal ridges of posterior teeth and the incisal
edges of the incisors determine the curve of Spee.3 The
presence of curve of Spee of variable depth is a common
Tayyaba Bibi, BDS, Orthodontics resident Khyber College of Dentistry, Peshawar Address: Department of Orthodontics, Khyber
College of Dentistry, Peshawar E-mail: [email protected]
2
Ahsan Mahmood Shah, BDS, FCPS (Orthodontics) Assistant Professor Orthodontics, Khyber College of Dentistry, Peshawar
Received for Publication:
January 7, 2017
Revised:
February 20, 2017
Approved:
February 22, 2017
1
finding in the occlusal arrangement of the dentition.
From functional perspective COS has a biomechanical
function by increasing the crush-shear ratio between
posterior teeth and the efficiency of occlusal forces
during mastication.4
A possible explanation for the development of the
curve of Spee is the earlier eruption of mandibular
permanent teeth before maxillary counterparts. On
average, mandibular first molar erupts 1-2 months
earlier than maxillary first molars and eruption of
mandibular permanent incisors preceds the maxillary
counterparts by 12 months. Due to differential timing
of eruption, this could permit the mandibular first
molars and incisors to erupt beyond the established
occlusal plane.5 This implies that the development of
curve of Spee is a dental phenomenon. However several
factors contribute to the development of curve of Spee
including dental eruption timing, craniofacial variation
and neuromuscular system.6
In deciduous dentition the COS is suggested to range
from flat to mild whereas curve of Spee in permanent
Pakistan Oral & Dental Journal Vol 37, No. 1 (January-March 2017)
66
Curve of spee/vertical eruption of teeth
dentition tends to be deeper. In humans curve of Spee
of increasing depth is common to brachycephalic facial
pattern and associated with short mandibular bodies.7
Andrews8 described 6 keys to normal occlusion by
studying 120 untreated subjects with pleasing appearance and normal occlusion and stated curve of Spee as
the sixth key to normal occlusion ranging from flat to
mild curve. He further stated that there is a natural
tendency for cuve of Spee to deepen with time due to
continued growth of the lower jaw compared to upper
jaw. Therefore, leveling COS during orthodontic treatment is recommended for good intercuspation.
Orthodontics and prosthetics dentistry differ with
respect to the clinical significance of COS. Its proper
arrangement is critical for fabrication of stable complete dentures.9 Leveling of the excessive curve of Spee
inevitably increases arch length as this leads to incisor
protrusion unless molars are moved distally, which
is difficult.10 Baldridge11 reported that decreasing the
depth of the curve of Spee leads to an increase in arch
circumference as the lower incisors will procline in
direct response.
A deep curve of Spee is usually associated with
increased overbite.12 Orthodontic correction of deep bite
involves leveling of curve of Spee by anterior intrusion,
posterior extrusion or a combination of these.13 Schudy14
proposed the correction of deepbite and deep curve of
Spee by posterior extrusion because intrusion of anterior teeth tends to relapse. The aim of this study was
to evaluate the correlation between vertical pattern
of teeth and curve of Spee in various malocclusion
groups in order to better understand the contribution
of anterior or posterior tooth eruption to development
of curve of Spee in individual malocclusion type.
METHODOLOGY
This retrospective, cross-sectionsl study was carried
out at Department of Orthodontics, Khyber College of
Dentistry between May 2016 to August 2016, using
lateral cephalograms and dental casts of patients. The
records of 120 patients were selected on the basis of
inclusion criteria:
1
Presence of all permanent teeth except third molar
2 Patients having class I, class II div 1/div 2, class
III dental malocculusion
3
Mild crowding or spacing with well aligned arches
4 Cephalograms of high clarity.
Those patients with previous history of orthodontic
therapy, prosthetic replacement of missing teeth and
fractured dental casts were excluded. Pretreatment
lateral cephalograms and dental casts were obtained
and divided into 4 equal groups according to type of
dental malocclusion: class I (mean age 19.8±3.6 years),
class II div 1 (mean age 17.3±3.9 years), class II div
2 (mean age 16.433±2.824 years) and class III (mean
age 21.4±5.5 years). The depth of curve of Spee was
measured on dental casts as advocated by Marshall et
al7 i.e the perpendicular distance between the deepest
cusp tip and a flat plane touching the incisal edges of
the incisors and distobuccal cusp tip of most posterior
teeth of the mandibular arch as shown in Fig 1.
Pretreatment lateral cephalograms of patients were
obtained by using Kodac - 9000 C machine with film size
of 11×14. Measurements were made by a single operator
after tracing the landmarks manually using illuminator.
The reference points on lateral cephalogram were: L1
(the incisal tip of mandibular central incisor), M7 (the
distobuccal cusp tip of mandibular second molar) and
point S (the deepest point of COS). The planes used
were: mandibular plane (the line between gonion and
gnathion); L1-MP (the perpendicular distance from
L1 to mandibular plane); L7-MP (the perpendicular
distance from L7 to mandibualr plane) and S-MP (the
perpendicular distance from deepest point of COS to
the mandibular plane) Fig 2. The mean values of COS
and cephalometric measurements were recorded for
each patient.
STATISTICAL ANALYSIS
The data was analyzed using SPSS version 20.0.
Mean ±SD was calculated for numerical variables like
curve of Spee and age according to malocclusion type.
The correlation between curve of Spee and vertical
eruption of anterior/posterior was assessed by Pearson
correlation test and coefficients were determined for
curve of Spee and LI-MP/S-MP and L7-MP/S-MP. The
level of significance was set at 0.05 (p-value).
RESULTS
The sample of 120 patients was divided into four
malocclusion classes and their mean ages stratified by
gender are given in Table 1. Class III male subjects had
advanced mean age (23.56 ± 6.02 years) as compared
to other classes of malocclusion. Our sample curve of
Spee ranged from 1.40mm to 2.80mm (Table 2). The
maximum value for COS was found in class II div 2
2.80±0.41mm while minimum depth of1.40±0.69 mm
was in class I malocclusion. The second premolar cusp
tip was found to be the deepest part of COS while the
curve varied in depth as class II div 2 >class II div
1>class III>class I.
The statistical results for Pearson correlation
revealed significant association between COS and LIMP/S-MP and L7-MP/S-MP. The correlation between
LI-MP/S-MP and COS was significant for class I (r=
0.610) and class III (r= 0.267) malocclusion groups. Also,
a significant positive correlation between L7-MP/S-MP
was found for class II div 1 (r = 0.19) and class II div
2 (r =0.23). The mean value for L7-MP/S-MP was 0.8
for all classes of malocclusion.
Pakistan Oral & Dental Journal Vol 37, No. 1 (January-March 2017)
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Curve of spee/vertical eruption of teeth
TABLE 1: AGE DISTRIBUTION ACCORDING
TO GENDER AMONG DIFFERENT
MALOCCLUSION TYPES
Malocclusion type
Male
Female
Age (y)
n
Age
n
Class I
16.33±3.77
6
20.67±3.13
24
Class II div 1
16.75±3.93
12
17.66±3.97
18
Class II div 2
17.2±3.11
10
16.05±2.66
20
Class III
23.56±6.02
18
18.33±2.69
12
TABLE 2: MEAN VALUES OF CURVE OF
SPEE AMONG DIFFERENT CLASSES OF
MALOCCLUSION
Malocclusion
Fig 2: Cephalometrics landmarks and measurements
Mean (mm)
SD
Class I
1.400
0.693
DISCUSSION
Class 2 Div 1
2.333
0.599
Class 2 Div 2
2.800
0.417
Class III
1.550
0.657
The objective of this cross-sectional study was to
determine depth of COS among different classes of
malocclusion and contribution of vertical eruption of
anterior or posterior teeth to its development. The
COS is a naturally occurring phenomenon and is routinely leveled during the first phase of comprehensive
orthodontic treatment. The depth of COS varies and
depends on several factors, one factor being the dental
eruption pattern.
It has been found that COS is minimal in primary
dentition; its depth increases in the mixed dentition
with the eruption of permanent molars and incisors.
Maximum depth is acquired with the eruption of second molar and remains stable throughout adolescence
and adulthood.7 Therefore due to its stable nature in
adolescence and adulthood sample was selected on the
basis of full set of permanent dentition except third
molars.
Different methods have been advocated by different
researchers regarding its measurement. Baldridge11
used the perpendicular distances from all teeth to the
occlusal plane on both sides while Sondhi et al1 employed the same method but for right side only. Bishara
et al16 measured the COS as the average of the sum
of the perpendicular distances to each cusp tip. Braun
et al17 used the sum of right and left side maximum
depth while Marshall et al7 employed the same with
the difference being average of the sum of maximum
depth of both sides. In our study we measured COS as
advocated by Veli et al5 and Marshall et al.7
Clinically, the COS is measured by placing a flat
plane touching the incisal edges anteriorly and distal
marginal ridges of the most posterior teeth.18 This is
in contrast to prosthetic dentistry where the curve
begins from cusp tip of mandibular canine and follows
the buccal cusp tips of posterior teeth.19 In our study
mandibular incisors were used as the anterior limit of
the curve as to determine the contribution of anterior
vertical eruption to its development.
The effect of craniofacial morphology on COS has
been investigated in several studies with conflicting
TABLE 3: PEARSON CORRELATION BETWEEN
CURVE OF SPEE AND VARIABLES DETERMINING VERTICAL ERUPTION OF TEETH AMONG
VARIOUS MALOCCLUSION GROUPS
Group
Measurement
Mean
SD
r
Class I
L1-MP/S-MP
1.2350
0.065 0.670**
L7-MP/S-MP
.8317
0.050
0.012
Class II
div 1
L1-MP/S-MP
1.3206
0.075
0.194
L7-MP/S-MP
.8585
0.064
0.191
Class II
div 2
L1-MP/L7-MP
1.2743
0.074
0.138
L7-MP/S-MP
.8576
0.051
0.235
Class III
L1-MP/S-MP
1.2305
0.065
0.267
L7-MP/S-MP
0.8063
0.063
0.040
**correlation is significant at 0.01 level (2-tailed)
Fig 1: Measurement of curve of Spee on dental cast
Pakistan Oral & Dental Journal Vol 37, No. 1 (January-March 2017)
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Curve of spee/vertical eruption of teeth
results. A positive correlation was found in a study
by Batham et al4 whereas Kumar and Tamizharasi20
reported a minor influence of cranioskeletal morphology
on COS. Hence patients in this study were included on
the basis of dental malocclusion rather than skeletal
malocclusion.
In this study the curve of Spee was deepest for class
II div 2 and minimal for class I with the depth varied
as class II div 2>class II div 1>class III>class I. The
finding of deeper COS in class II div 2 compared to class
II div 1 is consistent with the findings of Ahmed et al.3
However Veli et al5 found class II div 1 to be greater in
the depth compared to class II div 2. This difference may
be attributed to difference in ethnicity and population
being studied. Shanon and Nanda12 found that class
II malocclusion had significantly greater COS than in
class I malocclusion supporting our study.
The deepest point of the curve was consistently
found to be the second premolar cusp which is similar
to the findings of and Batham et al4, Koyama21 and Lie
F.22 Our study disagree the study conducted by Veli et
al5 and Garcia23 who found mesiobuccal cusp tip of first
permanent molar as the deepest point.
In this study a correlation between vertical eruption
of anterior or posterior teeth and COS was evaluated. It
was found that eruption of anterior teeth was positively
correlated to COS in class I and Class III malocclusion
with a striking correlation of 0.670 for class I. This
finding is very close to 0.541 found in another study.5
Among class II malocclusion, posterior eruption of
teeth was found to significant contributor to the depth
of COS. Consistent with other studies, COS was found
deeper in class II malocclusion.
The cross sectional design of this study has a limitation regarding development of COS which should be
studied longitudinally. Moreover small sample size was
used and the effect of skeletal pattern on COS was not
assessed as the literature shows conflicting results.
This study provides a valuable data on depth of COS
among different malocclusion classes and compares it
with other studies for possible differences. It also provides an insight to contribution of vertical eruption to
COS development as no data is available in this region
and emphasis has been put to consider the contribution
of vertical eruption of teeth to its development during
diagnosis and treatment planning.
CONCLUSION
This study concludes its results as:
I The curve of Spee is deepest in class II div 2 malocclusion with the depth varying as: Class II div
2>Class II div 1>Class III>Class I.
II Second premolar cusp tip is the deepest point in
all types of malocclusion.
III Class I and Class III malocclusion has more anterior
eruption of teeth compared to other classes.
IV Posterior eruption was significant among Class II
malocclusion than in other classes.
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CONTRIBUTIONS BY AUTHORS
1 Tayyaba Bibi:
Paper writing, data collection, statistical analysis.
2 Ahsan Mahmood Shah: Topic selection, proof reading.
Pakistan Oral & Dental Journal Vol 37, No. 1 (January-March 2017)
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