Ethical approval
The study protocol conducted at college of dentistry, King Saud University included two phases: a retrospective review of CBCT scans and a standardized Arabic-validated disease-specific tool, a Chronic Sinusitis Survey (CSS). Ethical approval was granted by the Institutional Review Board (Project No. E-21-5974).
Imaging selection and interpretations
CBCT scans from 2017 to 2020 at the Department of Maxillofacial Radiology, in which patients were referred from the endodontic department for CBCT imaging of the maxillary posterior area to evaluate post-endodontic disease were included.
Retrospective evaluation of a high-quality technical image with appropriate sharpness, density, and contrast, visibly showing the maxillary posterior teeth apices and sinus floor. Totally edentulous maxilla or the presence of motion or beam-hardening artifacts in the maxillary periapical areas were excluded.
Assessment
CBCT scans were obtained using Planmeca ProMax 3D Plus [Planmeca Co., Helsinki, Finland]. The field of view ranged from small to large according to the original area of interest, and the parameters used were 90 kVp, 11 mA, 12.146 s, and 200 μm voxel size. The CBCT images were assessed by an oral and maxillofacial radiologist for sinus variables and an endodontist for dental variables using Planmeca Romexis® software. Each scan was reviewed in all sections including coronal, axial, and sagittal view to assess the individual area.
Radiographic assessment
The sinus floor and MT in relation to the involved teeth were evaluated in coronal sections by measuring the thickness in millimeters at the maximum area perpendicular to the bone. Based on this measurement, the sinus floor was categorized for MT as present (>1 mm) or absent (<1 mm). Furthermore, the presence of mucosal thickening was classified as localized or generalized (Fig. 1A, B).
Confounding variables
The number of dental conditions, including tooth type and either single or multiple teeth, was assessed in relation to MT, periodontal status, presence or absence of periapical lesion (PA), and adequacy of endodontic treatment. In addition to radiographic and clinical assessments, the age, sex, and systemic disease of the patients were recorded.
CSS
This survey was used to assess the clinical symptoms of persistent chronic sinusitis. Patients who underwent CBCT and met the inclusion criteria were contacted by phone and asked about their status of chronic sinusitis using CSS. This survey is a valid, disease-specific questionnaire to assess the health status of chronic rhinosinusitis (17). The questionnaire was translated to Arabic, validated, and provided open access to researchers (18). The survey consisted of two parts as follow: symptom and medication-based sections. The symptoms assessed were sinus headache or facial pain, nasal drainage, and nasal obstruction. The medication-based section included the use of antibiotics, nasal spray, and sinus medications. The section asks questions based on the duration of symptoms over 8 weeks.
Statistical analysis
The variables analyzed were mucosal thickness, periapical lesions of the teeth and roots, tooth type, patient sex and age, systemic factors, and CSS scores. Data were descriptively analyzed (frequencies, means, and standard deviations) to summarize the sociodemographic and clinical characteristics of the study subjects. The associated variables among the age group, sex, systemic factors, periapical lesions, periodontal health, quality of endodontic treatment, and tooth type in relation to the absence or presence of MT were assessed using the chi-square test. Mean CSS scores were compared between sub-groups (presence or absence of MT) using one-way ANOVA. Logistic regression was used to calculate the odds ratio (OR) and assess the relative risk concerning local and systemic factors. All variables were dichotomized for the binary and logistic regression analyses. All analyses were performed using IBM SPSS Statistics software (version 28). (SPSS, Armonk, NY, USA). The level of significance was set at p < 0.05 and was considered statistically significant.