PREVALENCE OF INCIDENTAL FINDINGS IN MAXILLARY SINUS USING CONE BEAM COMPUTED TOMOGRAPHY – A RETROSPECTIVE STUDY

Shilpa Syam^1*, Uma Maheswari¹

ABSTRAC

Maxillary sinus pathologies and normal variations in the sinus anatomy can result in complications during surgical interventions. Hence, maxillofacial radiologists should be knowledgable regarding thes radiographic findings poiting to pathologies/variations.

To study the prevalence of various incidental findings in the maxillary sinus region using cone beam computed tomography (CBCT). This was a retrospective- cross sectional study. CBCT scans of sixty patients who have been advised radiographs exclusively for dental complaints were retrospectively collected and examined for maxillary sinus pathologies. Their frequencies as well as unilateral/ bilateral involvement were recorded and analyzed. The most prevalent incidental finding of the maxillary sinus was mucosal thickening followed by septations. Few cases presented with infrequent findings like sinus floor discontinuity and root canal sealant inside the sinus. Significant maxillary sinus pathologies may present without any associated symptoms. Hence, oral radiologists examining CBCT scans should mandatorily evaluate the entire volume of the scan and any abnormal finding must be identified and reported to the clinician.

Keywords: Maxillary antrum, Incidental finding, Cone beam computed tomography, Mucosal thickening, Sinus opacification

Introduction

Maxillary sinus pathologies are frequently encountered by dentists during the radiographic assessment of patients with teeth-related complaints. Also, maxillary sinus pathologies are observed as incidental radiographic findings in asymptomatic patients who are evaluated for implant assessment, endodontic therapy, impacted/ supernumerary teeth and orthodontic correction [1]. A variety of imaging modalities including plain films as well as advanced radiographs provide visualization of maxillary sinus. Computed tomography, although is the gold standard out of these, has limitations of high radiation exposure and cost [2, 3]. Cone beam computed tomography (CBCT) which is being widely used now by the dentists for an array of indications, also is a good option for studying maxillary sinus. Despite of its poor soft tissue contrast, CBCT images can aid in viewing inflammatory pathologies and sinus opacification [4].

The prevalence of maxillary sinus pathologies in asymptomatic patients ranged widely between 10.9 % and 69.1 % across studies in literature [5-9]. Maxillary sinus abnormalities can be classified as developmental, inflammatory, cystic, calcifications or neoplasms [10]. The most commonly encountered being the lesions of imflammatory origin. Radiographically, these may appear as mucosal thickening (MT) or as sinus opacification (SO) [11]. The presence of an air-fluid level can also be a sign of inflammation implying acute sinus disease [12]. The cystic lesions of maxillary sinus can be retention cysts or mucoceles. Blockage of secretory ducts of seromucinous glands causing submucosal accumulation of secretions result in a pseudocyst called the mucous retention cyst. This is viewed in radiographs well defined non corticated, smooth, dome shaped, mostly sessile radiopaque mass [13]. Mucoceles on the other hand are expansile destructive masses due to a blocked sinus ostium and can appear as completely opacified maxillary sinus [14]. Maxillary sinus polyps are formed by thickened mucous membrane of chronically inflamed sinus which form polypoid folds which may be isolated or multiple [15].

Deposition of mineral salts such as calcium phosphate and calcium carbonate around the nidus results in a maxillary antrolith. Smaller antroliths are asymptomatic and are discovered as incidental findings [16, 17]. Radiographically, these appear as radiopaque structures of varying densities, with a well-defined periphery. They can have smooth or irregular borders and at times an internal structure resembling laminations [18].

Hence, it is evident that numerous pathologies can develop asymptomatically in the maxillary sinus region. Because we dentists evaluate CBCT scans of patients that involve the maxillary sinus region in our day-to-day practice, we must be knowledgeable to identify such lesions and advise proper management when necessary. This study aimed to assess the prevalence of various incidental findings in the maxillary sinus region using CBCT.

Materials and Methods

CBCT scans of sixty patients who were referred to the oral radiology department of a dental college were collected retrospectively. CBCT scans covering either the upper arch alone or both upper and lower arches, allowing adequate visualization of bilateral maxillary sinus regions, were included. Patients who were advised to radiograph exclusively for dental complaints were included and those suspected of having sinus-related pathologies clinically were excluded. Patients below the age of 18 years and those above 50 years were excluded from the study.

A thickening of mucosal membrane measuring > 3mm was considered pathological (Figure 1). Also, homogenously radiopaque mass with a convex/ polypoid shape, of any etiology, was radiographically recorded as a polypoidal thickening (PT). In addition to the frequency of various pathologies (Figure 2), the involvement of the sinus by the lesion was also noted and recorded as unilateral or bilateral.

Results and Discussion

The most prevalent incidental finding was MT followed by separations, OPA, air-fluid level, PT, antrolith, and sinus floor discontinuity. Root canal sealant was observed in one case which was the least prevalent abnormal finding. Also most of the pathologies had a bilateral presentation whereas less than half of the cases showed a unilateral involvement (Figures 3 and 4).

In our study out of the 60 patients, CBCT scans of 80% had incident findings in relation to the maxillary sinus and 20% had none. In a similar study done by Mamta Raghav et. al., 59.7 % of the study sample had incidental findings in the maxillary sinus [4].

In our study, the most prevalent incidental finding was MT (31.66%) followed by septations (18.33%) in the maxillary sinus. The normal thickness of the maxillary sinus mucosa is 0.8–1 mm, and with no consensus about how thick the mucosa should be for mucosal thickening literature. The maxillary sinus mucosa thickness value varies between 2-6 mm for the diagnosis of 'mucosal thickening'. In a study by Pazera et al. 1 mm was taken as the cut-off value [19]. Following Lana et al., the current study accepted a value of 3 mm [20]. Variability in the rate of mucosal thickness may be because the researchers accepted different threshold values and the patient criteria included in the study were different. Ritter et. al., reported MT followed by OPA and PT to be the most frequent findings [21]. These studies have not mentioned the prevalence of septations as individual findings and have rather grouped them along with other findings. This could be probably due to more focus on lesions. But we highlight the high prevalence of maxillary sinus septations in our study especially since it is significant for surgical planning in certain cases of implant and sinus lift procedures [22]. Also, the frequency of OPA (11.66 %) and PT (6.66 %) was lower compared to that reported in these studies. But these prevalence rates were consistent with another study conducted by Lim CG et al. in using CT scans [23]. The mucous retention cyst and antrochoanal polyp represent polypoid lesions of the maxillary sinus. The first lesion is a common asymptomatic incidental finding that can be viewed at 2%–5% rate on radiographic examinations. It is characterized by a dome-shaped radiopacity, extending from the sinus wall. The second lesion is a benign polypoid lesion that originates from the maxillary sinus mucosa and extends through its ostium to the choana. As both polypoid lesions show fluid density in the sinus on CT, they cannot be differentiated only with CT findings. For that reason, both have been grouped under the same heading in the current study, following Lana et al. [20].

Air Fluid Level CC Ani et al.

Eleven patients (9.3%) were found with maxillary mucosal thickening associated with a fluid level. The presence of an air-fluid level implied acute sinus disease and mucosal thickening in a normal-sized maxillary sinus suggested chronic sinusitis. Opacified maxillary sinus (partial or complete) had been described in other studies and might have either fluid or solid material as its content. Maxillary mucosal thickening with air-fluid level indicated an acute on the chronic process.

Antrolith

Antroliths are pathologic calcifications formed as a result of mineral salt deposition in the paranasal sinuses and show up as radiopaque masses with different sizes and shapes in the radiographic examination. Antrolith incidence was between 0.15%–4.54% in the literature. This incidence was 1.3% in the current study and our results were in accordance with other studies.

Foreign Body

Foreign bodies may access the maxillary sinus via an oroantral fistula. This can also occur through tooth extraction or root canal treatment (RCT) or because of surgical procedures in the maxillary sinus. While the current study found foreign bodies in the maxillary sinus at a rate of 0.3%, Lana et al. found this rate to be 1.6% [20].

OAF

Oroantral fistula is a common complication of dental surgery. Surgical treatment should be done so that normal sinus function can resume and inflamed sinus mucosa can heal. While Rege et al. found the incidence of the oroantral fistula rate to be 2.2%, Price et al. found it to be 2.7% in their study, and nine of these cases involved implant patients [24, 25]. The current study examined patients who underwent CBCT imaging for implant treatment and we found the oroantral fistula percentage as 0.3%. This result is quite lower than in the aforementioned research.

Conclusion

This study reported a very high incidence of incidental findings on CBCT evaluation of maxillary sinus.  Hence, radiologists should mandatorily evaluate the entire CBCT section and report the pathological as well as incidental findings, if any, so as to avoid complications during surgical procedures.

Acknowledgments: None

Conflict of interest: None

Financial support: None

Ethics statement: None

1.        Flaiban E, Alonso MB, Freitas CF, Torres FC, Lipiec-Ximenes M, Costa AL. Incidental findings in patients evaluated with cone beam computed tomography for orthodontic treatment. RGO-Rev Gaúcha Odontol. 2017;65(2):134-8.

2.        Jain S, Choudhary K, Nagi R, Shukla S, Kaur N, Grover D. New evolution of cone-beam computed tomography in dentistry: Combining digital technologies. Imaging Sci Dent. 2019;49(3):179-90.

3.        Tassoker M. What are the risk factors for maxillary sinus pathologies? A CBCT study. Oral Radiol. 2020;36(1):80-4.

4.        Mao W, Gardner SJ, Snyder KC, Wen NW, Zhong H, Li H, et al. On the improvement of CBCT image quality for soft tissue-based SRS localization. J Appl Clin Med Phys. 2018;19(6):177-84.

5.        Chandran A, Patil MB, Nachiappan S, Panwar PS, Nagarajappa AK, Kolte DR, et al. Accidental Pathological Findings in Asymptomatic Maxillary Sinuses in Patients Referred for Head and Neck Cone-Beam Computed Tomography: A Cross-sectional Study Analysis. J Med Signals Sens. 2022;12(2):138-44.

6.        Da Silva AF, Fróes GR Jr, Takeshita WM, Da Fonte JB, De Melo MF, Sousa Melo SL. Prevalence of pathologic findings in the floor of the maxillary sinuses on cone beam computed tomography images. Gen Dent. 2017;65(2):28-32.

7.        Ata-Ali J, Diago-Vilalta JV, Melo M, Bagán L, Soldini MC, Di-Nardo C, et al. What is the frequency of anatomical variations and pathological findings in maxillary sinuses among patients subjected to maxillofacial cone beam computed tomography? A systematic review. Med Oral Patol Oral Cir Bucal. 2017;22(4):e400.

8.        Wang W, Jin L, Ge H, Zhang F. Analysis of the Prevalence, Location, and Morphology of Maxillary Sinus Septa in a Northern Chinese Population by Cone Beam Computed Tomography. Comput Math Methods Med. 2022;2022:1644734.

9.        Özcan İ, Göksel S, Çakır-Karabaş H, Ünsal G. CBCT analysis of haller cells: relationship with accessory maxillary ostium and maxillary sinus pathologies. Oral Radiol. 2021;37(3):502-6.

10.     Bornstein MM, Yeung AWK, Tanaka R, von Arx T, Jacobs R, Khong PL. Evaluation of Health or Pathology of Bilateral Maxillary Sinuses in Patients Referred for Cone Beam Computed Tomography Using a Low-Dose Protocol. Int J Periodontics Restorative Dent. 2018;38(5):699-710.

11.     Hsiao YJ, Yang J, Resnik RR, Suzuki JB. Prevalence of maxillary sinus pathology based on cone-beam computed tomography evaluation of multiethnicity dental school population. Implant Dent. 2019;28(4):356-66.

12.     Drumond JP, Allegro BB, Novo NF, de Miranda SL, Sendyk WR. Evaluation of the Prevalence of Maxillary Sinuses Abnormalities through Spiral Computed Tomography (CT). Int Arch Otorhinolaryngol. 2017;21(2):126-33.

13.     Peñarrocha-Oltra S, Soto-Peñaloza D, Bagán-Debón L, Bagan JV, Peñarrocha-Oltra D. Association between maxillary sinus pathology and odontogenic lesions in patients evaluated by cone beam computed tomography. A systematic review and meta-analysis. Med Oral Patol Oral Cir Bucal. 2020;25(1):e34-e48.

14.     Yeung AWK, Tanaka R, Khong PL, von Arx T, Bornstein MM. Frequency, location, and association with dental pathology of mucous retention cysts in the maxillary sinus. A radiographic study using cone beam computed tomography (CBCT). Clin Oral Investig. 2018;22(3):1175-83.

15.     Zadsirjan S, Sheikhi M, Dakhilalian A, Feli M. Association of Inflammatory Periapical Lesions with Maxillary Sinus Abnormalities: a Retrospective Cone-Beam Computed Tomography Study. J Dent (Shiraz). 2021;22(4):273-80.

16.     Harouak H, Ibijbijen J, Nassiri L. Comparison between Medicinal Plants Used Against Oral Diseases and Pharmaceutical Dental Products in Morocco. Ann Dent Spec. 2019;7(2):1-4.

17.     Asgari I, Soltani S, Sadeghi SM. Effects of iron products on decay, tooth microhardness, and dental discoloration: a systematic review. Arch Pharm Pract. 2020;11(1):60-82.

18.     Cho BH, Jung YH, Hwang JJ. Maxillary antroliths detected by cone-beam computed tomography in an adult dental population. Imaging Sci Dent. 2019;49(1):59-63.

19.     Pazera P, Bornstein MM, Pazera A, Sendi P, Katsaros C. Incidental maxillary sinus findings in orthodontic patients: A radiographic analysis using cone-beam computed tomography (CBCT). Orthod Craniofac Res. 2011;14(1):17-24.

20.     Lana JP, Carneiro PM, Machado Vde C, de Souza PE, Manzi FR, Horta MC. Anatomic variations and lesions of the maxillary sinus detected in cone beam computed tomography for dental implants. Clin Oral Implants Res. 2012;23(12):1398-403.

21.     Ritter L, Lutz J, Neugebauer J, Scheer M, Dreiseidler T, Zinser MJ, et al. Prevalence of pathologic findings in the maxillary sinus in cone-beam computerized tomography. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2011;111(5):634-40.

22.     Ilavenil K, Guru AT, Gugapriya TS, Nalinakumari SD. Maxillary Sinus Septation: A Radiological Study. Int J Sci Study. 2015;3(2):101-4.

23.     Lim CG, Spanger M. Incidental maxillary sinus findings in patients referred for head and neck CT angiography. Singapore Dent J. 2012;33(1):1‐4.

24.     Rege IC, Sousa TO, Leles CR, Mendonca EF. Occurrence of maxillary sinus abnormalities detected by cone beam CT in asymptomatic patients. BMC Oral Health. 2012;12(1):30.

25.     Price JB, Thaw KL, Tyndall DA, Ludlow JB, Padilla RJ. Incidental findings from cone beam computed tomography of the maxillofacial region: A descriptive retrospective study. Clin Oral Impl Res. 2012;23(11):1261-8.