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 Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 30  |  Issue : 1  |  Page : 18-23

Prevalence of anatomical variations in maxillary sinus using cone beam computed tomography


1 Department of OMDR, Aditya Dental College, Beed, Maharashtra, India
2 Department of OMDR, Govt Dental College and Hospital, Nagpur, Maharashtra, India
3 Department of OMDR, DY Patil Dental College, Chinchwad, Maharashtra, India
4 Department of OMDR, M.A. Rangoonwala Dental College, Pune, Maharashtra, India

Date of Submission24-Aug-2017
Date of Acceptance17-Feb-2018
Date of Web Publication23-Apr-2018

Correspondence Address:
Dr. Deepjyoti K Mudgade
Department of OMDR, Aditya Dental College, Beed, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jiaomr.jiaomr_81_17

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   Abstract 


Introduction: The maxillary sinuses (MS) are of particular importance to dentist because of their close proximity to the teeth and their associated structures, so increased risk of maxillary sinusitis has been reported with periapical abscess, periodontal diseases, dental trauma, tooth extraction, and implant placement. Complications of MS are related to its anatomic and pathologic variations. Thus, study was conducted to assess the prevalence of anatomic variations in MS by using cone-beam computerized tomography (CBCT). Aims and Objectives: To determine different anatomical variations in MS by using CBCT. Materials and Methods: CBCT scans of 150 subjects were collected between the age group of 18 years to 70 years and were analyzed for MS anatomical variation. Statistical Analysis: The distribution of age, sex, reasons for CBCT, and dimensions of sinus calculated using descriptive statistics and distribution of other anatomic findings using Chi-square test. Results: Prevalence of obstructed ostium is 23.3% and septa is 66.7%. Average height, width, and antero-posterior (A-P) dimensions for right MS are 34.13 mm, 26.09 mm, 37.39 mm and that of left MS are 33.24 mm, 26.11 mm, 37.72 mm respectively. Average distance between lower border of ostium to sinus floor in right MS is 32.17 mm and that of left is 32.69 mm. Average diameter of ostium in right MS is 1.88 mm and that of left is 1.67 mm. Conclusion: Study highlights the importance of accurate assessment of MS and its variations in order to properly differentiate the pathologic lesions from anatomic variations avoiding unnecessary surgical explorations.

Keywords: CBCT, maxillary sinus, ostium, septa


How to cite this article:
Mudgade DK, Motghare PC, Kunjir GU, Darwade AD, Raut AS. Prevalence of anatomical variations in maxillary sinus using cone beam computed tomography. J Indian Acad Oral Med Radiol 2018;30:18-23

How to cite this URL:
Mudgade DK, Motghare PC, Kunjir GU, Darwade AD, Raut AS. Prevalence of anatomical variations in maxillary sinus using cone beam computed tomography. J Indian Acad Oral Med Radiol [serial online] 2018 [cited 2020 Apr 8];30:18-23. Available from: http://www.jiaomr.in/text.asp?2018/30/1/18/230898




   Introduction Top


The paranasal sinuses are four paired sets of air-filled cavities of craniofacial complex.[1] The very close relationship between teeth roots and maxillary sinus (MS) is referred to as “draping.”[2] Complications of MS are related to its anatomic and pathologic variations.[3]

MS are small at birth, after birth, the MS enlarges with the growing maxilla, though it is fully developed following the eruption of permanent dentition.[4]. MS anatomy varies from person to person. The main characteristics of these structures are pneumatic. Genetic diseases, environmental conditions, and past infections can affect the process of pneumatization of maxillary sinuses. The size of maxillary air sinuses are reported to increase with age.[5]

MS communicates with the homolateral nasal fossa by means of a natural ostium located posterosuperiorly on the medial surface.[6] Normal physiology of the MS is highly dependent on the proper function of both the MS ostium and the mucosal lining.

Underwood was the first to define MS septa as they are walls of cortical bone within the MS, their shape has been described as an inverted gothic arch arising from the inferior or lateral walls of the sinus, and may even divide the sinus into two or more cavities. Location of the septa inside the sinus is repeated in different individuals due to their development at three different moments of tooth eruption.[7]

Anatomic variations within the sinus, such as septa, increase the risk of the sinus membrane perforation during pre-implant surgery in posterior maxilla. Computed tomography (CT) images allow the location of anatomic structures and provide information about bone dimensions and morphology.[8]

The advent of cone-beam computerized tomography (CBCT) is its lower cost, smaller device size, and CBCT can produce an image with significantly less radiation than traditional CT, because it uses an image intensifier, this is particularly important for children. CBCT provides excellent tissue contrast, eliminates blurring, and overlapping of adjacent structures.[9]

It is important to study MS by CBCT as it has become the standard imaging modality for visualizing the MS because of its ability to visualize both bone and soft tissue in multiple views with thin sectioning, having both axial and coronal views which allows the clinician to assess the relationship of a periapical lesion to a sinus floor defect and any resultant changes in the soft tissue of the sinus.[10]

CBCT scans which does not include the ostium, infundibulum, and ethmoidal cells, does not allow an assessment of the MS drainage system, and the dental surgeon cannot predict the safety of the planned procedure. When the demonstrated lower portion of the MS is completely aerated, dentists usually assume normal sinus function and continue with their surgical plan. Therefore, it is essential to analyze sinus anatomy completely including the osteomeatal complex.[11]

CBCT can accurately capture, display, and provide 3-dimensional visualization of maxillofacial anatomy and pathology [12]

So this study is planned to assess the prevalence of anatomic findings and variations in MS by using CBCT as it provides diagnostic information which is essential in clinical decision making, better treatment planning and predictable outcomes.


   Materials and Methods Top


In our retrospective study, CBCT scans of 150 subjects were collected between age group of 18 years to 70 years from different private dental clinics and CBCT centers which were referred for CBCT examination of the maxillofacial region. Only those subject's scans were included in the study whose examinations were performed using i-CAT CBCT machine with Vision software (Imaging Science International) and who have given a signed informed consent on an institutionally approved document.

Linear measurements of maxillary sinus: Measurement of height (H), width (W), antero-posterior (A-P) dimensions

The linear measurements were performed by selection of the cuts which was based on the presence of certain anatomical landmarks. According to the anatomical fact that the MS is pyramidal in shape with an almost square base oriented medially, the measurements of the sinus dimensions were conducted as follows:

  1. Linear measurements of the MS height on sagittal section (craniocaudal extension; CC [Figure 1]
  2. Linear measurements of the MS width (mediolateral dimension) and antero-posterior (A-P) dimensions on axial section [Figure 2].
Figure 1: Linear measurements of the maxillary sinus height (H): Taken on sagittal view

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Figure 2: Linear measurements of the maxillary sinus width (W) and antero-posterioR (A-P) dimensions: (Taken in axial view)

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Measurement of ostium: Measurement of ostium diameter, and distance between lower border of ostium and sinus floor and to check patency of ostium [Figure 3], [Figure 4], [Figure 5].
Figure 3: Measurement of ostium diameter (coronal view)

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Figure 4: Measurement of distance between lower border of ostium and sinus floor. (coronal view)

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Figure 5: Obstructed ostium

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Presence of septa: Septa were diagnosed using three orthogonal slice views: axial, coronal, sagittal and orthopantomogram [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6].
Figure 6: Presence of septa (Panoramic View)

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Statistical analysis

Distribution of sex, age and dimensions of MS was noted using descriptive statistics from the obtained data. The distribution of other anatomic findings in MS was calculated using Chi-square test.


   Results Top


Our study includes data of 150 subjects, which includes 300 maxillary sinuses. Following the statistical analyses the various data obtained were tabulated and described in the form of tables and graphs.

Out of 150 subjects included in our study total number of male subjects observed were 67 (44.7%) and female subjects were 83 (55.3%) [Graph 1].



Considering the inclusion and exclusion criteria of the study the minimum age of patient included in study was 19 years and maximum age of patient was 69 years. All the subjects included in our study were divided into five age groups, i.e., 19–29, 30–39, 40–49, 50–59, 60–69.

In age group 19–29, the total numbers of subjects studied were 10 (6.7%). In age group 30–39, the total numbers of subjects studied were 12 (8.0%). In age group 40–49, the total number of subjects studied was 29 (19.3.0%). In age group 50–59, the total numbers of subjects studied were 37 (24.7.0%). In age group 60–69, the total numbers of subjects studied were 62 (41.3.0%). Minimum number of subjects were studied in age group 19–29 and maximum number of subjects were studied in age group 60–69 [Graph 2].



The reason for which CBCT was advised was recorded as it was different for every subject, it is recorded under following headings: implant purpose, surgical purpose, orthodontic purpose, postoperative trauma evaluation purpose, prosthetic purpose, and any other reason. Out of total 150 subjects, 73 subjects, has a reason of implant purpose, i.e., (48.7%), 51 subjects, has a reason of prosthetic purpose, i.e., (34.0%) 16 subjects, has reason of surgical purpose, i.e., (10.7%), five subjects, has reason of orthodontic purpose, i.e., (3.3%), four subjects, has reason of any other purpose, i.e., (3.3%).

Implant purpose is highly indicated reason for CBCT followed by prosthetic purpose and surgical purpose, and postoperative trauma evaluation is least indication for CBCT in our study. There was no statistically significant difference between different indications groups for CBCT scans [Graph 3].



Height measurement of right MS showed average minimum height of 18 mm and average maximum height of 51.75 mm, showing mean value as 34.13 mm and standard deviation (SD) value as 5.36 mm and for left MS average minimum height of 3 mm and average maximum height of 50.00 mm, showing mean value as 33.24 mm and SD value as 5.39 mm. It showed that height of right MS is larger than left sinus [Table 1].
Table 1: Dimensions of maxillary sinus

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It showed that width of left MS is larger than right sinus [Table 1]. Average minimum width of right MS was 14 mm and average maximum width of right MS was 36.3 mm. Average minimum width of left MS was 3.75 mm and average maximum width of left MS was 36.76. It showed that width of left MS (mean 26.11 mm and SD value 4.87 mm) was larger than right MS (mean 26.09 mm & SD value 4.24 mm) [Table 1].

Average minimum A-P dimension of right MS was 23.76 mm and average maximum A-P dimension of right MS was 47.75 mm. Average minimum A-P dimension of left MS was 1.12 mm and average maximum A-P dimension of left MS was 47.25 mm. It showed that A-P dimension of left MS (mean value 37.72 mm, SD 4.60) is larger than right MS (mean value 37.39 mm, SD 4.07) [Table 1].

Average minimum diameter of ostium of right MS was 0.50 mm and average maximum diameter of ostium of right MS was 5.51 mm. Average minimum diameter of ostium of left MS was 0.50 mm and average maximum diameter of ostium of left MS was 5.37 mm It showed that diameter of ostium of right MS (mean value 1.88mm, SD 0.91 mm) is larger than left sinus (mean value 1.67 mm, SD 0.82 mm) [Table 1].

Average minimum distance from lower border of ostium to floor of right MS was 17.90 mm and average maximum distance from lower border of ostium to floor of right MS was 45.48 mm. Average minimum distance from lower border of ostium to floor of left MS was 21 mm and average maximum distance from lower border of ostium to floor of left MS was 53.36 mm. It showed that distance from lower border of ostium to floor of sinus in left MS (Mean Value 32.69 mm, SD 5.36 mm) is larger than right sinus (Mean Value 32.17 mm, SD 5.31 mm) [Table 1].

Out of all the 150 CBCT scans studied, total 51 subjects showed obstructed ostium. Right sided ostium was obstructed in 26 subjects (17.3%) and left sided ostium was obstructed in 25 subjects (16.7%). Overall prevalence of obstructed ostium in our study is 23.3% [Table 2].
Table 2: Distribution of other anatomic findings in maxillary sinus

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Both the sinuses were evaluated for the presence of septae, in which 97 subjects, i.e., (64.7%) showed presence of septa in right MS and 99 subjects, i.e., (66%) showed presence of septa in left MS. The overall prevalence of septa is 66.7%. Obstructed ostium and presence of septa did not differ significantly between right and left maxillary sinuses. (Chi-square value = 0.036, P value = 0.850 (NS) [Table 2].


   Discussion Top


It has been reported that maxillary sinuses stay intact though the skull and other bones may be severely disfigured in victims who are incinerated and hence, that maxillary sinuses can be used for identification.[13]

The maxillary sinuses are of particular importance to the dentist because of their proximity to the dental structures. Consequently, diseases of the sinuses may mimic odontogenic disease, and conversely, odontogenic disease may spread to the sinuses or mimic sinus disease.

Maxillary sinuses may appear on radiographs made for dental purposes, including maxillary periapical and extraoral radiographs such as panoramic radiographs and lateral cephalometric radiographs. Therefore, the dentist should have some familiarity with the normal appearances and more common diseases of the maxillary sinuses.[2]

Considering the anatomical variability of the MS, its proximity with posterior teeth and pneumatization, a three-dimensional assessment of MS for the presence of septa, obstructed ostium, and its linear measurement is most useful.

In our study the parameters of right MS (mean Value) calculated wereas follows: height 34.13 mm, width 26.09 mm, Antero-Posterior dimension (A-P) 37.39 mm and that of left MS were as follows: height 33.24 mm, width 26.11 mm, Antero-Posterior dimension (A-P) 37.72 mm. Whereas in the study by Hamdy [14] showed the largest average measurements of MS as height 31.54 mm, width 20.43 mm, and Antero-Posterior dimension (A-P) 35.54 mm. Tiwana et al.[15] stated that 33 mm height, 23 mm width, and 34 mm in an Antero-Posterior dimension (A-P) length were the average dimension of the MS.

Study by Shahbazian et al.[16] revealed that the Antero-Posterior dimension (A-P) and mediolateral dimensions of MS were in the range of 38 mm and 23.5 mm, respectively. Yet, their study did not mention information about the craniocaudal extension of the sinus. Similar measurements were found byBaweja et al.[17] who notedaverage of A-P; transverse and vertical dimensions as 3.35 ± 0.53 cm, 2.17 ± 0.35 cm, and 3.71 ± 0.74 cm, respectively.

In our study, average diameter of ostium in right MS was 1.88 mm and that of left side was 1.67 mm and average distance between lower border of ostium to sinus floor in right side was 32.17 mm and that of left side was 32.69 mm.

Similar findings were shown by Ritter et al.[6] the mean diameter of the MS ostium was 1.797 mm on the left and 1.792 on the right side, and distance between lower border of ostium to MS floor was 31.91 on the right side and distance between lower border of ostium to MS floor was 31.91 on the left side was 32.02 mm on the left. This similarity in results may be due to similar measurement criteria used in our study to that of criteria used in both studies.

Septa are walls of cortical bone within the MS, with a shape as inverted gothic arch arising from any of the MS wall. In our study, the prevalence of septa was 66.7% [Table 2] which was in contrast with the study by Dobele et al.[11] reported (20.6%), Lugmayr et al.[18] reported (13%), Krennmair et al.[19] reported (18.8%), Ulm et al.[20] reported (31.7%)., Ritter et al.[6] reported (47%), Shiki et al.[21] reported 49%, Velásquez-Plata et al.[22] reported (24%), Kim et al.[23] reported (26.5%), González-Santana et al.[24] reported (25%). Results of Underwood [7] who reported 66.7% were in accordance with the present study. The prevalence of septa in other studies varies with that of our study that may be due to septa calculation which was based either percentage of sinuses or percentage of patients and also it can be due to different material or imaging modality used to study septa prevalence.

The MS communicates with the homolateral nasal fossa by means of a natural ostium.

In our study obstructed ostium showed prevalence of 23.3% [Table 2] which was in similar range with study by Dobele et al.[11] who found prevalence of 26.5% of obstructed ostium. While Carmeli et al.[25] found 15% prevalence of obstructed ostium which was quite less than our observations.

The intraoral periapical radiograph provides the most detailed but limited view of the floor of the maxillary antrum. The conventional radiographs does not give the clear visualization of maxillary sinuses because of their own limitations, CT and magnetic resonance imaging (MRI) were proved to be good imaging modality for evaluation of maxillary sinuses but because of higher radiation exposure in CT and high cost factor in MRI, cone-beam computed tomography (CBCT) is gaining importance for evaluation of sinus.[9]


   Conclusion Top


CBCT provide multiple sections through the sinuses in different planes, they help in delineating the extent of disease and the final diagnosis. High-resolution axial, coronal, and sagittal sections are the most revealing, noninvasive techniques for the MS anatomy, pathology and its adjacent structures and areas.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
 
 
    Tables

  [Table 1], [Table 2]



 

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