Journal of International Oral Health

ORIGINAL RESEARCH
Year
: 2018  |  Volume : 10  |  Issue : 2  |  Page : 94--98

Sella turcica bridging a diagnostic marker for impacted canines and supernumerary teeth


S Divya1, Arun S Urala1, G Lakshmi Prasad2, Kalyan C Pentapati3,  
1 Department of Orthodontics, Manipal College of Dental Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, India
2 Department of Neurosurgery, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India
3 Department of Public Health Dentistry, Manipal College of Dental Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, India

Correspondence Address:
Dr. S Divya
Department of Orthodontics, Manipal College of Dental Sciences, Room 7, Manipal - 576 104, Karnataka
India

Abstract

Aims: Altered sella turcica morphology, sella turcica bridging, or calcification of the interclinoidal ligament (ICL) of the sella turcica has been associated with various dental anomalies. To investigate whether impacted canines or the presence of hyperdontia (supernumerary teeth) is associated with sellar bridging, a retrospective study was done. The aim of the study was to check the frequency of sella turcica bridging in participants with impacted canines and hyperdontia compared with a control group. Material and Methods: Determination of the extent of sella turcica bridging was carried out using lateral cephalometric radiographs from 39 patients with impacted canines and 23 patients with hyperdontia or supernumerary teeth. The extent of the sella turcica bridging on each lateral cephalogram was assessed based on a standardized scoring scale (Type I, II, and III) and then compared with those of the control group consisting of 36 patients. Results: The frequency of complete calcification of ICL (Type III bridging) in patients with impacted canines and hyperdontia was 17.9% and 21.7%, whereas 5.6% was found in the control group. A partially calcified ICL (Type II bridging) was observed in 43.6% and 21.7% of patients with impacted canines and hyperdontia compared with 19.7% in the control group. P < 0.05 was considered statistically significant according to Chi-square statistics which proved the frequency of sella turcica bridging in patients with dental anomalies is increased. Conclusion: The frequency of sella turcica bridging is positively associated and increased in patients with impacted canines and hyperdontia when compared to a control group. Sella turcica bridging can be used as a diagnostic marker of underlying dental anomalies such as impacted canines and hyperdontia.



How to cite this article:
Divya S, Urala AS, Prasad G L, Pentapati KC. Sella turcica bridging a diagnostic marker for impacted canines and supernumerary teeth.J Int Oral Health 2018;10:94-98


How to cite this URL:
Divya S, Urala AS, Prasad G L, Pentapati KC. Sella turcica bridging a diagnostic marker for impacted canines and supernumerary teeth. J Int Oral Health [serial online] 2018 [cited 2022 Jun 27 ];10:94-98
Available from: https://www.jioh.org/text.asp?2018/10/2/94/230878


Full Text

 Introduction



Dental anomalies can result from numerous factors, be it genetic, epigenetic, or environmental.[1] Several studies have investigated the prevalence of various dental anomalies, but only a few have addressed the correlation between dental anomalies and sella turcica bridging.

The sella turcica is a cephalometric landmark used by orthodontists for cephalometric analysis as a part of orthodontic treatment.[2] The sella turcica consists of a central hypophyseal fossa and two pairs of anterior and posterior clinoid processes. These anterior and posterior processes are connected by interclinoidal ligament (ICL). The sella turcica bridge (STB) is the true bony union of the anterior and posterior clinoid processes. The easiest way of diagnosing a sella turcica bridging is with a lateral skull–cephalometric radiography.[3] This sella turcica bridging in skeletal Class II and Class III malocclusions, dental anomalies, unilateral cleft lip and palate, severe craniofacial deviations, and in syndromes has been reported in previous studies.[4],[5],[6],[7],[8],[9] Hence, the aim of this study was to check the frequency of sella turcica bridging in participants with impacted canines and hyperdontia compared with a control group.

 Materials and Methods



This protocol was approved by the Institutional Ethical Committee Board (IEC Number: 533/2017).

This case–control study was performed with 98 pretreatment lateral cephalometric radiographs of three groups. The study group consisted of 62 orthodontic patients with impacted canines (39 participants – 30 maxillary and 9 mandibular) and hyperdontia (23 participants). The control group consisted of 36 orthodontic patients without the presence of any dental anomaly.

To collect the patient data, all pretreatment radiographs of orthodontic patients who visited the department (150 patients, time-bound sample – 6 months) were collected. The exclusion criteria comprised of incomplete patient files (lacking either lateral cephalograms or panoramic radiographs, poor image quality, presence of a cleft lip and palate/history of cleft lip and palate repair or other craniofacial anomaly or syndrome, trauma, and history of orthodontic treatment or surgeries).

For inclusion in the study, malocclusion type was not a criterion for sample selection. In the study group, the impacted canine group needed to have at least one impacted canine (with any depth, position, direction, or severity) and participants in hyperdontia needed to have at least one supernumerary tooth (mesiodens, paramolar, or distomolar). To be included in the control group, participants needed to have no dental anomalies at any degree of severity.

The description of the study sample is shown in [Table 1] and [Table 2].{Table 1}{Table 2}

Determination of the extent of sella turcica bridging

The length and diameter of the sella turcica were measured to quantify the extent of sella turcica bridging. The tip of the dorsum sella (DS) to the tuberculum sella (TS) was traced which formed the contour of the pituitary fossa. The length of the sella turcica (distance from the tip of the DS to the TS) and anteroposterior greatest diameter (distance from TS to the most posterior point on the inner wall of the pituitary fossa) will be measured [Figure 1].[10]{Figure 1}

The extent of the sella turcica bridging on each lateral cephalogram will be assessed based on a standardized scoring scale (Leonardi et al.):[11]

Type I (no calcification): Length of the sella turcica was greater than or equal to three-fourths of the diameter [Figure 2]aType II (ICL partially calcified): Length of the sella turcica was lesser than or equal to three-quarters of the diameter [Figure 2]bType III (ICL completely calcified): Radiographically visible diaphragma sella [Figure 2]c.{Figure 2}

The lateral cephalograms were traced and measured by one observer. The lateral cephalometric tracings were made on 0.003-inch thick acetate paper with 0.3 mm HB lead pencil and the landmarks were identified.

Statistical analysis was performed with SPSS version 18 software(Armonk, NY: IBM Corp). To assess the error of location of the reference points, 25 randomly selected radiographs were retraced and measured after 2 weeks. The difference between the first and second measurements of the 25 tracings was not significant.

Descriptive statistics were calculated for both the study and control groups. The Chi-squared test was used to determine the sella turcica bridging between the study and control groups. The level of significance was predetermined at P < 0.05.

 Results



In the control group, nine patients (25%) had sella bridging (Type II and III), and 24 patients (61.5%) with impacted canines and 10 patients (43.4%) with hyperdontia had this anomaly (Type II and III). The difference between the groups was statistically significant (P = 0.018). Chi-square test showed that the presence of partial and complete sella bridging in patients with impacted canines and hyperdontia is significantly more than in the control group [Table 3] and [Graph 1]. A comparison of the degree of sella turcica bridging in dental anomalies with other studies is shown in [Table 4].{Table 3}{Table 4}[INLINE:1]

 Discussion



Radiographic evidence of sella bridging/calcification of ICL on lateral cephalometric radiographs is typically recorded as a supplemental finding, unless there is a warranting clinical or historical condition.[2]

Radiographic studies have reported that sella bridging has been reported to be a diagnostic feature of other dental anomalies. In this study, the prevalence of sella turcica bridging was investigated in a group of patients with dental anomalies consisting of impacted canines [Figure 3] or supernumerary teeth [Figure 4] and compared with normal participants.{Figure 3}{Figure 4}

According to a review of literature, canine impactions are twice as common in females (1.17%) as in males (0.51%). The prevalence of impacted maxillary canines is 0.9%–2.2%, but mandibular canine impaction occurs 20 times less frequently than maxillary canines,[17] whereas the prevalence of supernumerary teeth has been reported in several studies which ranged from 0.5% to 5.3%. In addition, the gender-wise prevalence of supernumerary teeth is predominantly seen in males than in females.[18] However, our results were consistent with the reported demographic data of both impacted canines and supernumerary teeth [Table 1].

The sella turcica bridging can be due to various possible causes. First, it must be ruled out that the bridging can be due to the superimposition of structures and there is no real bony fusion. Second, a STB could be a malformation from prenatal life. It has been suggested that, at an early stage of development, interclinoid ligament is laid down in cartilage and then ossifies in very early childhood. Hence, according to this, a STB should be considered a developmental anomaly. Formation of the sellar bridges may result directly from the pattern of sphenoid development or the physiological activities of chemical compounds that are involved in embryogenesis.[8]

During embryological development, the neural crest cells migrate to the frontonasal and maxillary developmental fields. The calcifications of the ICL may be associated to the dental anomalies as they share the common embryological developmental pathway.[19],[20] This anatomical variation of the sella turcica may reflect the developing pathological conditions of the oral cavity which may alert the clinician in predicting the susceptibility to dental anomalies.

In the present work, we tried to investigate the sella bridging in both maxillary (30 participants) and mandibular impacted canines (9 subjects) and supernumerary teeth (23 participants). It has been the first study to investigate the prevalence of sella turcica bridging in patients with dental anomalies among the Indian population.

Till now, researchers focused their attention mainly on sella bridging in malposed maxillary canines be it palatally displaced or impacted canines, highly placed canines, combination of buccal and palatal canine impactions.[12],[13],[14],[15] However, there are only a few studies reported on the combination of dental anomalies such as palatally displaced canines and missing mandibular second premolar, transposition.[11],[16] Until now, the only study that analyzed the prevalence of a STB in relation to various dental anomalies such as palatally and vestibular impacted canines, upper lateral incisors, and lower second premolar agenesis, and hyperdontia was conducted by Scribante et al.[6]

It has been demonstrated that the presence of partial and complete bridging is significantly increased in patients with dental anomalies versus control group which were consistent with the few previous reports.

This study was limited by few factors. Lateral cephalograms were used in the study which is a two-dimensional representation of a three-dimensional object and has its own errors such as landmarks identification and tracings errors. Therefore, cone-beam computed tomography, a three-dimensional imaging, could give more precise representation. However, such imaging techniques in orthodontic patients are not indicated due to the higher exposure to radiation for routine use. A higher sample size inclusion with different dental anomalies would yield more significant results.

 Conclusion



The sella turcica bridging may not be closely inspected during cephalometric analysis. However, the detection of sella turcica bridging or calcification of the ICL may help in the early diagnosis or susceptibility to such dental problems.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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