The Prevalence of the Carabelli Cusp in a Selected Saudi Population
*Mohammed Al-Sultan, BDS
*Mansour Al-Askar, BDS
*Mohammed Al-Katheeri, BDS
**Salah Al-Shethri, BDS, MDS
***Abdulaziz Al-Rasheed, BDS, MS, DABP
:‫الملخص‬
‫حدبة كارابيلي هي ُحديبة أو نتوء صغير عادة توجد على السطح الحنكي من الحدبة األنسية الحنكية لألرحاء العلوية الدائمة واألرحاء‬
‫ الهدف من هذه الدراسة هو تبيين انتشار ودرجة وضوح حدبة كارابيلي وحدوث نخر األسنان فيها على األرحاء‬.‫الثانية اللبنية العلوية‬
‫ مريضا ً سعوديا ً حضروا إلى كلية طب‬672 ‫ تم عشوائيا ً فحص‬.‫العلوية األولى والثانية الدائمة في عينة مختارة من السعوديين‬
‫ استثنيت األرحاء األولى والثانية العلوية التي بها‬.‫ سنة‬55 -11 ‫أعمارهم تتراوح بين‬. ‫األسنان بجامعة الملك سعود في مدينة الرياض‬
‫ كان انتشار‬.‫ فـُحص الرحى األول والثاني بعناية لوجود الحدبة وحدوث نخر األسنان‬.‫نخر شديد أو مرممة أو مفقودة في أي جهة‬
‫ ثنائية الجانب لألرحاء‬/ 4278‫ ثنائية الجانب لألرحاء العلوية األولى و‬/ 2176 ‫ في كل العينة و بنسبة‬/ 5772 ‫حدبة كارابيلي بنسبة‬
. / 5575 ‫ أما الموجودة كشرفات بارزة فكانت بنسبة‬/ 6277 ‫ أما بالنسبة للشرفات الموجودة كالثلمات فكانت بنسبة‬.‫العلوية الثانية‬
. ‫استنتج من هذه الدراسة أن أكثر من نصف المجتمع السعودي لديه حدبة كارابيلي وأن وجودها مرتبط بزيادة حدوث نخر األسنان‬
: ‫الصلة السريرية‬
‫الحدبات والثلمات البارزة قد تكون بؤرة الحتباس اللويحة الجرثومية وتطور نخر األسنان والحديبة الكبيرة قد تعيق وضع حلقات تقويم‬
. ‫األسنان وأخيرا ً المعلومات المجموعة من هذه الدراسة قد يستفاد منها لغرض التعليم‬
Abstract:
The carabelli cusp is a tubercle or cuspule, or a groove often seen on the palatal surface of the mesiopalatal cusp of
maxillary permanent molars and maxillary second deciduous molars. The purpose of this study was to determine the
prevalence, degree of expression of the carabelli structure, and caries prevalence in the carabelli structure in the permanent
first and second maxillary molars in a selected Saudi population. 276 Saudi patients attending to the college of dentistry in
King Saud University in Riyadh city were randomly selected for examination. Their age ranged from 11-55 years old.
Patients with severely carious, restored or missing upper first or second maxillary molars on any side were excluded. Both
the first and the second upper molars were carefully examined for the occurrence of the Carabelli structure and the presence
of caries. The prevalence of the carabelli structure was 57.6% with a bilateralism of 91.2% in the first maxillary molars and
86.4% in the second molars. The Carabelli structure was found to be 29.7% as a groove expression, and 35.5% as a cusp
expression. It was concluded that more than half of the Saudi population have a degree of expression of the carabelli
structure and the Carabelli trait is associated with increased caries incidence.
Clinical relevance: Prominent pits and grooves can be a foci of plaque retention and caries development, a large tubercle
can pose some problems with orthodontic bands, and finally data collected from this study can be used for teaching
purposes.
Introduction:
The carabelli structure is a tubercle or cuspule,
or a groove, often seen on the palatal surface of
the mesiopalatal cusp of maxillary permanent
molars and maxillary second deciduous molars1.It
includes a variety of expressions that range from
complete absence to pits, grooves, tubercles,
cusplet, or cusps2. It represents the end product of
the interaction of a complex system of ontogenetic
and environmental factors1.
* Intern, College of Dentistry, King Saud University, Riyadh, Saudi
Arabia.
** Lecturer, Restorative Division, Department of Restorative Dental
Sciences, College of Dentistry, King Saud University, Riyadh, Saudi
Arabia.
*** Lecturer, Periodontic Division, Department of Preventive Dental
Sciences, College of Dentistry, King Saud University, Riyadh, Saudi
Arabia.
Alvesalo et al3 (1975) examined 233 patients
in a Finnish rural population for the presence of
the carabelli cusp. 79% of them had the cusp in
first upper molars. The occurrence of the structure
was bilateral with varying degrees of asymmetry.
Their results suggested low heritability of the
character. They classified the carabelli structure as
follows:
1. Smooth surface.
2. Single pit or furrow.
3. Double furrow or Y-shaped furrow.
4. Slight protuberance or small cusp.
5. Large cusp.
1
In a study made by Rusmah (1992)4, 320
maxillary casts of Malaysian children were
examined for the occurrence of the Carabelli trait
on the maxillary first permanent molars. The total
trait frequency was observed to be 51.6 %. The
cusp was observed to be more bilateral.
17.43% occurrence of the carabelli cusp in
maxillary molars was reported by Falomo (2002)5
after examining 2,604 Nigerians. There was
70.71% bilateralism in the upper first molars, with
1.98% simultaneous bilateralism in the upper first
and second molars. Unilateralism in the upper first
molars accounted for 25.99%.
The purpose of this study was to determine
the prevalence, degree of expression of the
carabelli structure, and caries prevalence in the
carabelli structure in the permanent first and
second maxillary molars in a selected Saudi
population.
Materials and methods:
276 Saudi patients attending to the college of
dentistry in King Saud University in Riyadh city
were randomly selected for examination. Their
age ranged from 11-55 years old. Any patient with
severely carious, restored or missing upper first or
second maxillary molars on any side was
excluded.
Both the first and the second upper molars
were carefully examined for the occurrence of the
structure and the presence of caries, from the
occlusal view using a mouth mirror and dental
explorer. Under efficient light condition, caries
presence was examined by pulling the explorer tip
over the groove created by the cusp looking for
stickiness, and avoiding apically directed force6,7,8.
The structure and its degree of expression was
classified into three categories:
1. Smooth surface or absence of the
structure.
2. Depression or groove.
3. Prominent cusp.
Three examiners collected the data. For interexaminer calibration, and before starting the data
collection, a teaching lesson with an expert
examiner was made to unify standards of
examination. At the beginning, 20 patients were
examined by all examiners, in which the first
examiner performed examination and recorded
data followed by the second and third examiners
in an orderly manner. The data was then crossmatched using the Kappa value.
All statistical analysis was calculated using
the SPSS program version 10, then descriptive
data analysis was used to report findings.
Results:
A high degree of interexaminer calibration
was observed with the first twenty patients
examined by the three examiners. The mean
Kappa values were 0.89 for the detection of the
carabelli structure and 1.00 for the detection of
caries.
Out of the 276 patients, 159 individuals had
some sort of expression of the carabelli trait
(57.6%) in relation to number of teeth, while the
remaining 117 patients did not have any
expression of the structure (42.4%), i.e. smooth
surface (Table 1). Table 2 shows that 35.5% of
patients had cusp expressions, while 29.7% had
groove expressions in at least one tooth. The
degree of expression of the carabelli trait in the
first and in the second maxillary molar teeth are
shown in tables 3 and 4 respectively.
Patient
frequency
Prevalence
(%)
Smooth Surface
117
42.4
Carabelli trait
159
57.6
Total
276
100
Structure
Table 1. Prevalence of patients having the carabelli trait.
Groove or Depression
Structure present in
Prominent Cusp
Patient
frequency
Percentage
(%)
Patient
frequency
Percentage
(%)
One out of the four molars
7
2.5
10
3.6
Two out of the four molars
67
24.3
68
24.6
Three out of the four molars
4
1.4
2
0.7
Four out of the four molars
4
1.4
18
6.5
Total
82
29.7
98
35.5
Table 2. Frequency and percentage of patients having the carabelli trait expression in
relation to number of teeth.
2
Tables 5 and 6 show the bilateralism of the
Carabelli structure in relation to the maxillary first
and second molars respectively. In the first
maxillary molar, the total bilateralism, regardless
of the type of expression, was found to be 91.2%,
of which 36.5% was groove bilateralism, and
54.7% was cusp bilateralism. And in the second
maxillary molar, Bilateralism was 86.4%, of
which 45.4% was groove bilateralism, and 41%
was cusp bilateralism. Simultaneous bilateralism
in the first and second molars, regardless of the
type of expression, was 7.97%.
Caries prevalence in the first and second
molars is shown in table 7. Teeth with no carabelli
structure had no caries. The prevalence of caries
in the Carabelli structure was the same (16.8%)
for the first and the second molars separately. For
the groove expression, caries prevalence was
2.9% in the first molar and 4.8% in the second
molar. And for the cusp expression, it was 13.9%
in the first molar and 12% in the second molar.
Upper first molar
Criteria
Absence of
structure
Groove or
depression
Prominent
cusp
Total
(N= 552)
Percentage
(%)
Total
%
242
43.8
43.8
125
22.7
185
33.5
552
100
Frequency
56.2
100
Table 3. Degree of expression of the carabelli trait in the
upper first molars
Upper second molar
Criteria
Absence of
structure
Groove or
depression
Prominent
cusp
Total
(N= 552)
Percentage
(%)
Total %
469
85
85
44
8
39
7
552
100
Frequency
15
100
Table 4. Degree of expression of the carabelli trait in the
upper second molars
Criteria
Groove or depression
unilaterally
Groove or depression
bilaterally
Prominent cusp
unilaterally
Groove on one side cusp on the other side
Prominent cusp
bilaterally
Carabelli
structure
Frequency
(N = 159)
Percentage
(%)
3
1.9
58
36.5
5
3.1
6
3.8
87
54.7
Table 5. Patient bilateralism in relation to the upper first
molars.
Criteria
Groove or depression
unilaterally
Groove or depression
bilaterally
Prominent cusp
unilaterally
Groove on one side cusp on the other side
Prominent cusp
bilaterally
Carabelli
structure
Frequency
(N = 44)
Percentage
(%)
3
6.8
20
45.4
2
4.5
1
2.3
18
41
Table 6. Patient bilateralism in relation to the upper second
molars.
Discussion:
Since three examiners collected the data, it
was important to unify and standardize their
method of examination and data collection. The
mean Kappa Values obtained were high, which
suggest that the three examiners reached an
excellent interexaminer reliability.
The present study reveals that more than one
half of the Saudi population have a degree of
expression of the Carabelli structure. The results
were very close to those reported by Rusmah
(1992) (51.6%). Prominent pits and grooves can
be a foci of plaque retention and caries development, and a large tubercle can pose some problems with orthodontic bands
Bilateralism of the trait, in this study, was
very high. This supports the findings of other
researchers 3,4,5,10,11, they agree that bilateralism of
the trait is more frequent. Although some
investigators, such as Biggerstaff (1973)1 and
(1972)9, suggested that bilateralism or mirroring is
not a factor in the carabelli trait, even among
twins. Simultaneous Bilateralism in the upper first
and second molars was found to be low, which
agrees with Falomo’s5 findings. An interesting
result was found, which is if the second upper
molars had prominent cusps bilaterally, the upper
first molars would have prominent cusps
3
First molar
Criteria
Smooth Surface
Carabelli
trait
(N = 552)
Caries
frequency
Frequency
percentage
(%)
242
0.0
0.0
No. of teeth
125
groove
310
cusp
Second molar
9
52
185
Frequency
percentage
(%)
469
0.0
0.0
2.9
16.8
43
(N = 552)
Caries
frequency
No. of teeth
44
83
4
14
13.9
39
4.8
16.8
10
12
Table 7. Frequency and percentage of caries in the first and second molars.
bilaterally as well. But it is not true for the
grooves. This could be attributed to genetics, as
some investiga-tors1,2,12,13,14 reported that it may
have a big influence on the carabelli trait.
Many studies3,4,11,15 failed to show any sex
dimorphism in the occurrence of the trait, although some investigators16,17 observed a sex-linked
pattern. Therefore, the relationship of sex to the
Carabelli trait was not investigated in this study.
In the first molars, it was found that the cusp
expression showed higher caries prevalence (23.3)
when compared to groove expression (7.2%), this
is true for the second molar as well. This finding
can be explained by the fact that the cusp
expression has a tubercle in addition to the groove;
this tubercle may act as a physical barrier against
the cleansing mechanisms of a tooth brush and
physiological cleaning by the tongue movement
and the salivary flow. In cases where the Carabelli
structure was absent, caries was not detected
which supports the idea that the Carabelli
structure presents a foci for plaque accumulation
and caries development. The method by which
caries was examined, i.e. avoiding apically
directed force, might have contributed to the low
caries prevelance6,7,8.
Future studies should be made to assess the
relationship of the carabelli trait to genetics and its
heritability. The carabelli trait should also be
studied in relation to sex.
Conclusion:
According to the criteria of the present study,
the following conclusions can be drawn:
1.
2.
The prevalence of the Carabelli trait
in a selected Saudi population was
57.6%.
The Carabelli trait is associated with
increased caries prevalence.
3.
Dentists are advised to perform a
careful examination to the lingual
surfaces of the maxillary first and
second molars to roll out the presence
of the Carabelli structure and caries.
Acknowledgment:
We wish to thank Dr. Nazeer Khan for his
help and assistance in the statistics used in this
research.
References:
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4
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