Comprehensive analysis of maxillary sinus anatomical features and associated characteristics: a CBCT-based study in a Saudi subpopulation

Abstract

Background

The maxillary sinus exhibits significant anatomical variation, influenced by sex, age and laterality. Understanding these morphological characteristics is essential for effective diagnostic and surgical planning in dentistry and maxillofacial procedures. Comprehensive Comprehensive cone-beam computed tomography (CBCT)-based evaluations in Saudi populations remain limited.

Objective

This study aimed to assess maxillary sinus anatomical features and dimensions using CBCT imaging in a Saudi subpopulation, examining associations with sex, side and age.

Methods

A retrospective, cross-sectional analysis was conducted on 1018 CBCT scans (2036 sinuses) of adults aged ≥ 18 years, obtained between January 2024 and January 2025 at a leading dental centre in Ha’il, Saudi Arabia. Sinus parameters, comprising width, length, area, perimeter, septa, fluid, and mucosal thickening, were measured. Statistical tests evaluated associations with sex, age and laterality.

Results

Sinus fluid was the most frequent abnormality and was significantly more common in male and older adults (p < 0.001). Sinus dimensions (width, length, area, perimeter) were significantly larger in male than in female (p < 0.001) and decreased progressively with age, particularly after the fifth decade. Bilateral dimensions were strongly correlated (ρ > 0.55, p < 0.001), confirming anatomical symmetry.

Conclusions

Maxillary sinus morphology varied significantly with sex and age in this Saudi population. Male and younger individuals exhibited larger sinus dimensions, and sinus pathology was more common in older adults. These findings underscore the value of CBCT imaging for individualised treatment planning and highlight the need for population-specific anatomical references in clinical and forensic contexts. These findings have implications for surgical planning and sex estimation in forensic cases.

Introduction

The maxillary sinus (MS) is the first paranasal sinus to develop. It is composed of two pyramid-shaped, mucosa-lined, air-filled chambers [1]. The morphological anatomy of the sinus varies by individual, sex, age and laterality (left or right side of the same person) [2]. The MS’s growth persists until the second and third decades of life in female and male, respectively [3]. Therefore, measuring MS dimensions and volume is considered useful to identify sex in forensic medicine [4]. The development of three-dimensional cone-beam computed tomography (CBCT), which offers high-resolution volumetric imaging faster and with less radiation exposure, made it a trustworthy method for assessing the anatomical structure and dimension characteristics of the MS [5].

The proximity of the MS to the nasal and oral cavities has made it of great interest to dental practitioners and obliges accurate diagnostic and treatment planning for successful outcomes [6]. Periapical disease in the maxillary first molars is the main origin for odontogenic MS pathophysiology [6]. Furthermore, various dental procedures depend on an understanding of the MS anatomy, including tooth extraction, preoperative planning for dental implant treatments, graft size prediction for sinus lift procedures, orthodontic mini-implant insertion and the prevention of potential complications in maxillofacial surgery [7].

In Saudi Arabia, scant studies have investigated the incidence, position and morphological variations of the MS septa, which is the bony structure divides the MS into several compartments, in Al-Qassim [8], Madinah [9] and Riyadh [10] populations to consider the clinical implications as well as the possible complications during sinus-related surgical procedures. The prevalence of the MS septa was varied among studies. It was 25.6% in Al-Qassim, with a moderate risk of Schneiderian membrane perforation [8], 39.6% in Madinah [9] and 72% in Riyadh [10]. While the location and the anatomical features were diverse among individuals therefore no certain conclusion was drawn [8–10].

Importantly, anatomical variations are population-specific, influenced by genetic, environmental and developmental factors. Hence, extrapolating findings from one demographic to another may lead to suboptimal treatment planning or increased risk during surgical interventions. Existing studies in Saudi Arabia have been limited to specific regions and focused primarily on septal prevalence without comprehensive dimensional or bilateral analysis. Wile Comprehensive anatomical and volumetric parameters concerning sex, side and age using large, representative samples have not yet been reported. Therefore, a detailed CBCT-based assessment of MS morphology in a broader Saudi subpopulation is essential to improve diagnostic accuracy and surgical planning. Hence, this study aimed to comprehensively investigate the anatomical features of the MS in Saudi Arabia by evaluating its dimensions and structural differences based on sex, side and age to improve treatment planning in dentistry and maxillofacial surgery using CBCT. The null hypothesis was no difference in the anatomical structures of MS based on sex, side or age among Sauid population.

Methodology

Ethical considerations

Ethical approval was obtained from the Institutional Review Board at the University of Ha’il, following ethical research guidelines (Approval No. H-2025-609). Due to the retrospective nature of the study, the Ethics Committee of the College of Dentistry at University of Ha’il waived the requirement for informed consent. All patient data were anonymised to ensure confidentiality and privacy.

Study design and setting

This cross-sectional retrospective observational study used CBCT scans to assess the anatomical features of the MS in a Saudi subpopulation, conducted at a leading dental centre in the Ha’il region, Saudi Arabia, from the 1 st of January 2024 to the 1 st of January 2025.

The inclusion criteria were patients aged > 18 years, with all permanent teeth (excluding third molars), no missing teeth in the maxillary posterior regions, and CBCT imaging performed for dental implant surgery, orthognathic surgery, impacted third molar surgery, or a cyst or tumour of dental structures not affecting the MS. Additionally, patients were required to have no pathology or trauma affecting the anatomy or integrity of the MS. Only CBCT scans with an adequate field of view (FOV) encompassing both maxillary sinuses, bilateral examination, complete visualization of sinus boundaries, and absence of motion or metallic artefacts were included.

The exclusion criteria were patients with pathological or traumatic conditions affecting the MS (e.g. fractures, inflammation, residual roots, overflowing endodontic material, cysts or tumours or conditions requiring surgery), a history of MS surgery; bone diseases (e.g. osteoporosis); skeletal asymmetries; congenital disorders; syndromic conditions; or orthodontic treatment (e.g. braces) during the imaging period.

Sample size calculation

The sample size was calculated using Daniel equation; 𝑛=Z² *P *(1-P)/d², where n = sample size, Z statistic for a 95% level of confidence, P is the expected prevalence based on the earlier study (9) and d is percision of 5%. The sample size was 366. A total of 1018 scans were used to ensure accuracy, reliability and generalisability of the findings.

Data collection

The scans were obtained using the CBCT machine Carestream CS 8100 3D (Carestream Dent LLC, Atlanta, USA). The X-ray generator operated within a range of 60–90 kV, 2–15 mA, and 140 kHz. This unit features a CMOS sensor and dental volumetric reconstruction capability. Scan times ranged from 3 to 15 s, with available fields of view of 4 × 4 cm, 5 × 5 cm, 8 × 5 cm, and 8 × 8 cm, and a minimum voxel size of 75 μm. Image analysis was conducted using CS 3D Imaging Software (Carestream Dent LLC, Atlanta, USA).

Out of the total 32,400 CBCT scan images initially reviewed, 1,018 were selected for inclusion in the study based on the predefined eligibility criteria. Before the evaluation process, the primary examiner underwent structured calibration training to ensure consistency, accuracy, and adherence to the assessment criteria. All CBCT images were reviewed and analysed by a single trained operator (YEA) to maintain uniformity in interpretation. This process was supervised by three senior observers (AAM, AFA, and AA), each with more than 10 years of clinical and radiological experience. The observers jointly established a standardized measurement protocol through consensus sessions on 20 randomly selected CBCT scans, agreeing on anatomical landmarks, measurement definitions, and image orientation. The first 50 cases were reviewed collectively with the operator to ensure adherence to this protocol, followed by periodic random checks of 10% of cases for quality control. Inter-evaluator agreement was further assessed on a random subset of 25% of cases, independently re-measured by the senior observers, with reliability tested using Cohen’s Kappa for categorical variables and ICC for continuous variables, both demonstrating excellent agreement (Kappa = 0.92; ICC > 0.90).

The collected data included patient sex, age, and sinus anatomical features comprising fluid, septa, membrane thickness, and abnormalities. All linear measurements were obtained on the coronal plane of the CBCT scans (Fig. 1). To ensure standardization, head orientation was adjusted so that the Frankfort horizontal plane was parallel to the floor before measurement. A single coronal slice was consistently selected at the level of the maxillary sinus ostium (widest anteroposterior and mediolateral extent) for all cases. This standardized slice served as the reference for subsequent dimensional and planimetric measurements. The sinus width was defined as the distance from the outermost point of the lateral wall to the medial wall (mm), while the length represented the longest anterior–posterior dimension of the cavity (mm). The planimetric area of the sinus cavity (cm²) was obtained by manually tracing the sinus boundary using the CS 3D Imaging Software, and the software simultaneously provided the perimeter (cm) of the traced region of interest.

Fig. 1.

CBCT image of the maxillary sinus illustrating the dimensional measurements applied in this study. The width was defined as the distance from the lateral wall to the medial wall, and the length as the greatest anterior–posterior dimension. The planimetric area was obtained by manually tracing the sinus boundary, while the perimeter represented the total length of the traced outline. All measurements were standardized on the coronal plane, with patient head orientation aligned to the Frankfort horizontal plane and the reference slice consistently selected at the level of the maxillary sinus ostium. Clinically, these dimensional parameters are critical for preoperative implant planning, sinus augmentation, and surgical navigation, as reduced dimensions or asymmetries may increase the risk of complications

Statistical analysis

SPSS version 23.0 was used to organise and analyse the data. Normality testing using the Shapiro–Wilk test indicated that the data were not normally distributed; therefore, non-parametric tests were applied. Descriptive statistics were employed to evaluate the frequency distribution of MS parameters, and comparisons were made based on sex and age. Chi-square test was employed to examine the associations between the anatomical features of the MS and the variables of age, sex and side. Subgroup comparisons were conducted using either the Mann–Whitney or the Kruskal–Wallis tests.To assess the correlation between corresponding anatomical features of the right and left MS, Spearman’s rank correlation coefficient was used. The reliability was assessed using Cohen’s Kappa for categorical variables (Kappa = 0.92), indicating excellent agreement. For continuous variables (e.g., sinus dimensions), reliability was evaluated using the intraclass correlation coefficient (ICC), which also demonstrated excellent consistency (ICC > 0.90). A p-value < 0.05 was considered statistically significant.

Results

A total of 2,036 MSs from 1,018 CBCT scans were analysed, comprising 446 male (43.8%) and 572 female (56.2%). The participants’ ages ranged from 18 to over 60 years, with most falling within the 18–25 (25.6%) and 31–40 (27.5%) age ranges (Table 1).

Table 1.

Descriptive distribution of demographic characteristics and maxillary sinus anatomical parameters

Variables	N (%)
Sex
Male	446 (43.8%)
Female	572 (56.2%)
Age
18–25 years old	261 (25.6%)
26–30 years old	104 (10.2%)
31–40 years old	280 (27.5%)
41–50 years old	228 (22.4%)
51–60 years old	104 (10.2%)
> 60 years old	41 (4.0%)
Right Maxillary Sinus Finding
Sinus Fluid	196 (19.3%)
Sinus Septa	65 (6.4%)
Thick Sinus Membrane	42 (4.1%)
Septa and Thick Sinus Membrane	16 (1.6%)
No Abnormality Detected	699 (68.7%)
Left Maxillary Sinus Finding
Sinus Fluid	186 (18.3%)
Sinus Septa	76 (7.5%)
Thick Sinus Membrane	41 (4.0%)
Septa and Thick Sinus Membrane	11 (1.1%)
No Abnormality Detected	704 (69.2%)
Right Maxillary Sinus Width
< 25 mm	170 (16.7%)
25–30 mm	478 (47%)
31–35 mm	333 (32.7%)
36–40 mm	31 (3.0%)
> 40 mm	6 (0.6%)
Left Maxillary Sinus Width
< 25 mm	204 (20%)
25–30 mm	480 (47.2%)
31–35 mm	304 (29.9%)
36–40 mm	29 (2.8%)
> 40 mm	1 (0.1%)
Right Maxillary Sinus Length
< 25 mm	19 (1.9%)
25–30 mm	111 (10.9%)
31–35 mm	461 (45.3%)
36–40 mm	370 (36.3%)
> 40 mm	57 (5.6%)
Left Maxillary Sinus Length
< 25 mm	17 (1.7%)
25–30 mm	153 (15.0%)
31–35 mm	477 (46.9%)
36–40 mm	345 (33.9%)
> 40 mm	26 (2.6%)
Right Maxillary Sinus Area
< 1000 cm2	536 (52.7%)
1000–1200 cm2	339 (33.3%)
> 1200 cm2	143 (14.0%)
Left Maxillary Sinus Area
< 1000 cm2	582 (57.2%)
1000–1200 cm2	335 (32.9%)
> 1200 cm2	101 (9.9%)
Right Maxillary Sinus Perimeter
< 125 cm	474 (46.6%)
126–135 cm	286 (28.1%)
> 135 cm	258 (25.3%)
Left Maxillary Sinus Perimeter
< 125 cm	523 (51.4%)
126–135 cm	314 (30.8%)
> 135 cm	181 (17.8%)

Prevalence of maxillary sinus findings

The most common abnormality was sinus fluid accumulation, observed in approximately one-fifth of sinuses, while septa and mucosal thickening were less frequent. Overall, about two-thirds of sinuses showed no detectable abnormalities (Table 1; Fig. 2).

Fig. 2.

Representative axial CBCT sections showing common anatomical variations and pathologies of the maxillary sinus observed in the study population. A Maxillary sinus with bony septa dividing the cavity; B sinus with septa and mucosal membrane thickening; C sinus exhibiting fluid accumulation; and D sinus with isolated mucosal membrane thickening. These variations highlight the diversity of sinus morphology relevant for diagnostic and surgical planning. These variations highlight the importance of CBCT evaluation in identifying risk factors that may affect surgical outcomes, implant stability, and postoperative healing

Detailed comparisons of sinus fluid prevalence by sex and age are presented in Table 2. Significant sex-based differences were observed, with sinus fluid more common in males than females on both sides (right: 27.1% vs. 13.1%, p < 0.001; left: 22.2% vs. 15.2%, p < 0.05). The prevalence of sinus fluid also varied significantly across age groups on both sides (right: p < 0.05; left: p < 0.001), being highest in individuals aged 41–50 years and above. Other anatomical variations, including sinus septa and membrane thickening, exhibited less pronounced but observable variability with age and sex. For example, sinus septa were more common in females (left side: 8.2%) and in individuals aged 18–25 years (10.0%), although these differences did not reach statistical significance (Table 2).

Table 2.

Prevalence of right and left maxillary sinus findings in relation to gender and age groups

Maxillary Sinus Findings		Sex			Age Groups
		Male	Female	P value	18–25 years old	26–30 years old	31–40 years old	41–50 years old	51–60 years old	> 60 years old	P value
Right	Sinus Fluid	121 (27.1%)	75 (13.1%)	< 0.001+	28 (10.7%)	17 (16.3%)	55 (19.6%)	59 (25.9%)	27 (26.0%)	10 (24.4%)	< 0.001#
	Sinus Septa	21 (4.7%)	44 (7.7%)	< 0.001+	27 (10.3%)	6 (5.8%)	11 (3.9%)	13 (5.7%)	7 (6.7%)	1 (2.4%)	< 0.001#
	Thick Sinus Membrane	20 (4.5%)	22 (3.8%)	0.966	10 (3.8%)	1 (1.0%)	14 (5.0%)	10 (4.4%)	4 (3.8%)	3 (7.3%	< 0.001#
	Septa and Thick Sinus Membrane	7 (1.6%)	9 (1.6%)	0.992	5 (1.9%)	2 (1.9%)	3 (1.1%)	2 (0.9%)	4 (3.8%)	0 (0.0%)	0.252
	No Abnormality Detected	277 (62.1%)	422 (73.7%)	< 0.001+	192 (73.6%)	78 (75%)	196 (70%)	144 (63.2%)	62 (59.6%)	27 (65.9%)	< 0.001#
P value	< 0.001*				0.009*
Left	Sinus Fluid	99 (22.2%)	87 (15.2%)	< 0.001+	23 (8.8%)	10 (9.6%)	65 (23.2%)	51 (22.4%)	27 (26.0%)	10 (24.4%)	< 0.001#
	Sinus Septa	29 (6.5%)	47 (8.2%)	0.001+	26 (10.0%)	4 (3.8%)	18 (6.4%)	13 (5.7%)	11 (10.6%)	4 (9.8%)	< 0.001#
	Thick Sinus Membrane	24 (5.4%)	17 (3%)	0.263	6 (2.3%)	3 (2.9%)	16 (5.7%)	8 (3.5%)	4 (3.8%)	4 (9.8%)	< 0.001#
	Septa and Thick Sinus Membrane	4 (0.9%)	7 (1.2%)	0.702	4 (1.5%)	1 (1.0%)	2 (0.7%)	3 (1.3%)	1 (1.0%)	0 (0.0%)	0.406
	No Abnormality Detected	290 (65%)	414 (72.4%)	< 0.001+	202 (77.4%)	86 (82.7%)	179 (63.9%)	153 (67.1%)	61 (58.7%)	23 (56.1%)	< 0.001#
P value	0.009*				0.001*

P-value calculated using Chi-square test. (*) means statistically significance (P-value < 0.05)

 P-value calculated using Mann–Whitney test. (⁺) means statistically significance (P-value < 0.05)

 P-value calculated using Kruskal–Wallis test. (^#) means statistically significance (P-value < 0.05)

Maxillary sinus dimensions

Anatomical measurements of the MS showed significant sex-based differences (Table 3). Across both sides, males consistently exhibited significantly larger sinus dimensions than females, including width, length, area, and perimeter (all p < 0.001). As shown in Table 3, these sex-related differences were most pronounced for sinus area and perimeter.

Table 3.

Distribution of maxillary sinus dimensions (width, length, area, perimeter) by gender and age group for both right and left sides

Maxillary Sinus			Sex			Age Groups
			Male	Female	P value	18–25 years old	26–30 years old	31–40 years old	41–50 years old	51–60 years old	> 60 years old	P value
Right	Width	< 25 mm	61 (13.7%)	109 (19.1%)	< 0.001+	46 (17.6%)	16 (15.4%)	38 (13.6%)	45 (19.7%)	18 (17.3%)	170 (16.7%)	0.994
		25–30 mm	181 (40.6%)	297 (51.9%)	< 0.001+	123 (47.1%)	53 (51.0%)	128 (45.7%)	110 (48.2%)	47 (45.2%)	478 (47.0%)	995
		31–35 mm	175 (39.2%)	158 (27.6%)	0.348	87 (33.3%)	31 (29.8%)	102 (36.4%)	64 (28.1%)	32 (30.8%)	333 (32.7%)	0.383
		36–40 mm	25 (5.6%)	6 (1.0%)	< 0.001+	4 (1.5%)	2 (1.9%)	10 (3.6%)	8 (3.5%)	7 (6.7%)	31 (3.0%)	0.383
		> 40 mm	4 (0.9%)	4 (0.9%)	1.000	1 (0.4%)	2 (1.9%)	2 (0.7%)	1 (0.4%)	0 (0.0%)	6 (0.6%)	0.990
	P value	< 0.001*				0.389
	Length	< 25 mm	6 (1.3%)	13 (2.3%)	< 0.001+	6 (2.3%)	4 (3.8%)	4 (1.4%)	3 (1.3%)	2 (1.9%)	0 (0.0%)	< 0.001#
		25–30 mm	46 (10.3%)	65 (10.3%)	0.096	34 (13.0%)	12 (11.5%)	26 (9.3%)	24 (10.5%)	9 (8.7%)	6 (14.6%)	0.368
		31–35 mm	169 (37.9%)	292 (51%)	0.007+	123 (47.1%)	45 (43.3%)	125 (44.6%)	109 (47.8%)	46 (44.2%)	13 (31.7%)	0.091
		36–40 mm	192 (43%)	178 (31.1%)	0.006+	88 (33.7%)	40 (38.5%)	106 (37.9%)	78 (34.2%)	40 (38.5%)	18 (43.9%)	0.331
		> 40 mm	33 (7.4%)	24 (4.2%)	0.553	10 (3.8%)	3 (2.9%)	19 (6.8%)	14 (6.1%)	7 (6.7%)	4 (9.8%)	0.540
	P value	< 0.001*				0.714
	Area	< 1000 cm2	196 (43.9%)	340 (59.4%)	< 0.001+	136 (52.1%)	57 (54.8%)	139 (49.6%)	132 (57.9%)	53 (51.0%)	19 (46.3%)	0.239
		1000–1200 cm2	160 (35.9%)	179 (31.3%)	0.034+	96 (36.8%)	33 (31.7%)	97 (34.6%)	67 (29.4%)	32 (30.8%)	14 (34.1%)	0.337
		> 1200 cm2	90 (20.2%)	53 (9.3%)	0.004+	29 (11.1%)	14 (13.5%)	44 (15.7%)	29 (12.7%)	19 (18.3%)	8 (19.5%)	0.643
	P value	< 0.001*				0.509
	Perimeter	< 125 cm	165 (37%)	309 (54%)	< 0.001+	123 (47.1%)	49 (47.1%)	120 (42.9%)	121 (53.1%)	45 (43.3%)	16 (39.0%)	0.327
		126–135 cm	128 (28.7%)	158 (27.6%)	0.003+	87 (33.3%)	32 (30.8%)	75 (26.8%)	52 (22.8%)	27 (26.0%)	13 (31.7%)	0.282
		> 135 cm	153 (34.3%)	105 (18.4%)	0.003+	51 (19.5%)	23 (22.1%)	85 (30.4%)	55 (24.1%)	32 (30.8%)	12 (29.3%)	0.480
	P value	< 0.001*				0.063
Left	Width	< 25 mm	95 (21.3%)	109 (19.1%)	0.983	42 (16.1%)	14 (13.5%)	57 (20.4%)	61 (26.8%)	20 (19.2%)	10 (24.4%)	0.589
		25–30 mm	189 (42.4%)	291 (50.9%)	< 0.001+	139 (53.3%)	56 (53.8%)	123 (43.9%)	98 (43.0%)	47 (45.2%)	17 (41.5%)	0.824
		31–35 mm	140 (31.4%)	164 (28.7%)	0.983	79 (30.3%)	29 (27.9%)	94 (33.6%)	58 (25.4%)	32 (30.8%)	12 (29.3%)	0.819
		36–40 mm	21 (4.7%)	8 (1.4%)	0.985	1 (0.4%)	5 (4.8%)	6 (2.1%)	10 (4.4%)	5 (4.8%)	2 (4.9%)	0.995
		> 40 mm	1 (0.2%)	0 (0.0%)	0	0 (0.0%)	0 (0.0%)	0 (0.0%)	1 (0.4%)	0 (0.0%)	0 (0.0%)	0
	P value	0.003*				0.038*
	Length	< 25 mm	8 (1.8%)	9 (1.6%)	0.585	6 (2.3%)	0 (0.0%)	5 (1.8%)	3 (1.3%)	1 (1.0%)	2 (4.9%)	0.447
		25–30 mm	66 (14.8%)	87 (15.2%)	0.037+	39 (14.9%)	12 (11.5%)	45 (16.1%)	38 (16.7%)	13 (12.5%)	6 (14.6%)	0.345
		31–35 mm	182 (40.8%)	295 (51.6%)	0.008+	119 (45.6%)	53 (51.0%)	119 (42.5%)	116 (50.9%)	54 (51.9%)	16 (39.0%)	0.273
		36–40 mm	173 (38.8%)	172 (30.1%)	0.155	93 (35.6%)	34 (32.6%)	106 (37.9%)	64 (28.1%)	33 (31.7%)	15 (36.6%)	0.288
		> 40 mm	17 (3.8%)	9 (1.6%)	0.150	4 (1.5%)	5 (4.8%)	5 (1.8%)	7 (3.1%)	3 (2.9%)	2 (4.9%)	0.290
	P value	0.002*				0.471
	Area	< 1000 cm2	231 (51.8%)	351 (61.4%)	< 0.001+	152 (58.2%)	55 (52.9%)	153 (54.6%)	141 (61.8%)	59 (56.7%)	22 (53.7%)	0.114
		1000–1200 cm2	148 (33.2%)	187 (32.7%)	< 0.001+	96 (36.8%)	34 (32.7%)	95 (33.9%)	65 (28.5%)	34 (32.7%)	11 (26.8%)	0.009#
		> 1200 cm2	67 (15%)	34 (5.9%)	0.023+	13 (5.0%)	15 (14.4%)	32 (11.4%)	22 (9.6%)	11 (10.6%)	8 (19.5%)	0.188
	P value	< 0.001*				0.059
	Perimeter	< 125 cm	210 (47.1%)	313 (54.7%)	< 0.001+	137 (52.5%)	47 (45.2%)	139 (49.6%)	130 (57.0%)	50 (48.1%)	20 (48.8%)	0.111
		126–135 cm	133 (29.8%)	181 (31.6%)	0.004+	87 (33.3%)	36 (34.6%)	87 (31.1%)	60 (26.3%)	35 (33.7%)	9 (22.0%)	0.107
		> 135 cm	103 (23.1%)	78 (13.6%)	0.041+	37 (14.2%)	21 (20.2%)	54 (19.3%)	38 (16.7%)	19 (18.3%)	12 (29.3%)	0.160
	P value	< 0.001*				0.262

P-value calculated using Chi-square test. (*) means statistically significance (P-value < 0.05)

P-value calculated using Mann–Whitney test. (⁺) means statistically significance (P-value < 0.05)

P-value calculated using Kruskal–Wallis test. (^#) means statistically significance (P-value < 0.05)

Bilateral association of findings

A statistically significant association was found between the presence of sinus abnormalities on the right and left sides (p < 0.001). Among cases with sinus fluid on the right, 45.4% also exhibited fluid on the left. Additionally, septa, thickened membranes and combined findings showed moderate levels of bilateral occurrence, supporting anatomical symmetry in pathological presentation as shown in Table 4.

Table 4.

Cross-tabulation of anatomical findings between right and left maxillary sinuses

Maxillary Sinus findings
Right Side Maxillary Sinus Findings	Left Side Maxillary Sinus Findings	N (%)	P Value
Sinus Fluid	Sinus Fluid	89 (45.4%)	< 0.001*
	Sinus Septa	2 (3.1%)
	Thick Sinus Membrane	9 (21.4%)
	Septa and Thick Sinus Membrane	6 (37.5%)
	No Abnormality Detected	80 (11.5)
Sinus Septa	Sinus Fluid	9 (4.6%)	< 0.001*
	Sinus Septa	30 (46.2%)
	Thick Sinus Membrane	0 (0.0%)
	Septa and Thick Sinus Membrane	34 (4.9%)
	No Abnormality Detected	3 (18.8%)
Thick Sinus Membrane	Sinus Fluid	5 (2.6%)	< 0.001*
	Sinus Septa	3 (4.6%)
	Thick Sinus Membrane	25 (59.5%)
	Septa and Thick Sinus Membrane	1 (6.3%)
	No Abnormality Detected	7 (3.3%)
Septa and Thick Sinus Membrane	Sinus Fluid	1 (0.5%)	< 0.001*
	Sinus Septa	3 (4.6%)
	Thick Sinus Membrane	1 (2.4%)
	Septa and Thick Sinus Membrane	4 (25.0%)
	No Abnormality Detected	2 (0.3%)
No Abnormality Detected	Sinus Fluid	92 (46.9%)	< 0.001*
	Sinus Septa	27 (41.5%)
	Thick Sinus Membrane	7 (16.7%)
	Septa and Thick Sinus Membrane	2 (12.5%)
	No Abnormality Detected	576 (82.5%)

P-value calculated using Chi-square test. (*) means statistically significance (P-value < 0.05)

Correlation between right and left sinus dimensions

Significant positive correlations were observed between the anatomical measurements of the right and left MSs, as presented in Table 5. These results demonstrate a high degree of bilateral symmetry in sinus morphology within the studied population.

Table 5.

Correlation between right and left maxillary sinus anatomical dimensions and findings

Maxillary Sinus	Right	Left	P Value
	Spearman’s rho
Sinus Findings	0.331		< 0.001*
Width	0.574
Length	0.560
Area	0.622
Perimeter	0.639

P-value calculated using Chi-square test. (*) means statistically significance (P-value < 0.05)

The sinus width exhibited a moderate correlation between sides (Spearman’s ρ = 0.574, p < 0.001), indicating that individuals with a broader sinus on one side tended to have a similarly broad sinus on the opposite side. Likewise, sinus length showed a statistically significant correlation (ρ = 0.560, p < 0.001), reflecting proportional development across both sides. Stronger correlations were noted for sinus area and perimeter, with coefficients of ρ = 0.622 and ρ = 0.639, respectively (p < 0.001 for both). These findings suggest that not only linear dimensions but also derived geometric characteristics of the sinus demonstrate substantial bilateral consistency. A moderate correlation was observed between right and left sinus findings, including fluid accumulation, septa and mucosal thickening (ρ = 0.331, p < 0.001). Although this correlation is lower than those seen in dimensional metrics, it still implies a degree of bilateral tendency in sinus pathologies.

Discussion

Variations in sinus size, the presence of septa and mucosal thickening significantly influence clinical decision-making. Additionally, the anatomical dimensions of the MS are critical for surgical planning in dentistry and otolaryngology [11–14]. Accordingly, this study presents a comprehensive CBCT-based evaluation of MS anatomical features, emphasising the impact of sex and age across a large sample population.

The null hypothesis that MS anatomy does not differ by sex, age, or side was partially rejected. Males exhibited significantly larger sinus dimensions and a higher prevalence of sinus fluid compared to females. Additionally, both sinus size and fluid prevalence varied across age groups, whereas bilateral symmetry was largely maintained. TThese findings highlight the influence of sex and age on MS anatomy and have clinical relevance for diagnosis and surgical planning.

This CBCT-based study revealed notable variations in the prevalence of MS abnormalities, specifically sinus fluid accumulation, sinus septa and mucosal membrane thickening. A statistically significant difference was observed in the distribution of sinus fluid between sexes, with male exhibiting a higher prevalence than female on both the right and left sides. Furthermore, the occurrence of sinus fluid increased progressively with age, reaching its highest frequency in individuals aged 31 to 60 years. These findings contrast with a pervious Saudi CBCT investigation that reported a high prevalence of sinusitis (50.6%) but found no significant associations with sex or age [14]. Likewise, a retrospective analysis conducted in Al-Hasa observed mucosal thickening in 63.3% of asymptomatic dental patients, yet demographic factors showed no correlation [15]. On the other hand, these findings align with those of previous studies, including Shiki et al. [16] and Yousef et al. [17]. Both documented a greater incidence of maxillary sinus mucosal thickening and fluid retention in male populations. This sex disparity may be attributed to lifestyle-related and environmental exposures more commonly experienced by male, such as tobacco use, occupational irritants and poor air quality, all of which can compromise sinus health and function. The age-related increase in sinus abnormalities may be explained by three factors: long-term exposure to environmental irritants, reduced mucociliary clearance with ageing, and a higher risk of dental infections or maxillary disease. Tadinada et al. [18] similarly suggested that long-term inflammatory or infectious stimuli could contribute to mucosal changes and sinus dysfunction over time, reinforcing the importance of early detection and preventive care.

The relatively high prevalence of sinus fluid observed in our study is clinically significant. Fluid accumulation may indicate subclinical or undiagnosed sinus disease, which can complicate maxillary sinus augmentation procedures, implant placement, and extractions of maxillary posterior teeth. Its higher frequency in male and older individuals highlights the importance of preoperative CBCT screening in these groups to reduce the risk of Schneiderian membrane perforation and postoperative sinusitis.

Sinus septa were more frequently observed in female on both the right and left sides; however, this difference did not reach statistical significance (p >0.05). The highest rates of septa occurrence were found in the 18–25 and 51–60 years age groups. Concerning septal prevalence, our findings are consistent with previous CBCT-based studies from various regions of Saudi Arabia. A study from the Madinah region reported that over 60% of maxillary sinuses lacked septa, while single septa were more frequent in younger individuals, with a slightly higher—but nonsignificant—prevalence in males [9]. Comparable observations were noted in another Saudi CBCT study, which highlighted morphological variations of sinus septa across different age groups [19]. Addtionally, these findings align with those reported by Krennmair et al. [20] and Türker et al. [21], who documented septa prevalence ranging between 10% and 35%, with considerable variability attributed to anatomical and developmental factors. The absence of a statistically significant association between sinus septa and sex or age in our study supports the widely accepted view that sinus septa are primarily congenital or developmental in origin rather than acquired through environmental or pathological processes. This interpretation is consistent with the broader literature, which emphasises individual anatomical variability as the primary determinant of septa presence. The prevalence of thickened sinus membranes was generally comparable between male and female, as well as across different age groups. However, a slight increase was noted among male participants and individuals over the age of 50. This trend, although not statistically significant, may reflect subtle influences of age- and sex-related factors. Shahbazian et al. [22] reported that sinus membrane thickening is frequently associated with underlying periapical pathology or chronic sinusitis, rather than being directly influenced by sex. Additionally, findings from Lu et al. [23] demonstrated a higher prevalence of membrane thickening in older populations, which aligns with the age-related pattern observed in this study. These results suggest that age-related changes in dental health and sinus drainage may contribute to increased mucosal thickening over time. Significantly more female showed no detectable MS abnormalities compared to male. Additionally, individuals aged 18–30 years exhibited the lowest prevalence of sinus abnormalities, with the rate of pathological findings progressively increasing with age. These findings are consistent with those reported by Tadinada et al. [18], who also observed a lower incidence of sinus pathology among female and younger age groups. This trend suggests that MS health may deteriorate with age, likely due to factors such as the accumulation of dental infections, age-related anatomical remodelling and prolonged exposure to chronic inflammatory conditions.

The width of the MS was significantly greater in male than in female on both sides. Male most commonly exhibited widths in the 25–35-mm range, whereas female showed a higher frequency of sinuses < 25 mm. Several studies have reported that male have larger MS dimensions than female, which is often attributed to larger craniofacial structures and hormonal influences on bone development. Our results regarding sex-related dimensional differences are consistent with previous CBCT-based studies from various provinces of Saudi Arabia. A study reported significantly larger sinus volumes in males (16,517 mm³) compared to females (13,595 mm³) [24]. Similarly, investigations in other regions, including Riyadh and Al-Hasa, documented greater mucosal membrane thickness and higher anatomical complexity in males undergoing sinus augmentation [25]. Furthermore, Tambawala et al. [26] and Al-Rawi et al. [27] also found significantly larger sinus widths in male, using CBCT imaging. Kocak et al. [28] found that male had a significantly larger sinus width and height, using CBCT in a Turkish population. MS length also showed significant differences by sex, with male more likely to have lengths ≥ 36 mm. This agrees with the findings of Prabhat et al. [29], who reported significantly greater anteroposterior lengths in male compared to female. Both area and perimeter were significantly larger in male, consistent with findings by Chatra et al. [30], who emphasised the reliability of area and perimeter differences in sex-based anthropometry of the sinus. The larger sinus dimensions in male are likely attributable to overall greater skeletal and craniofacial growth, as well as environmental and functional factors such as masticatory loading.

From a forensic perspective, the maxillary sinus offers a valuable anatomical marker because it is resistant to postmortem trauma and remains intact even when other skeletal structures are fragmented. The significant sex-related differences observed in our study (larger sinus dimensions in male) highlight its potential as a supplementary tool for sex estimation, especially in populations where conventional skeletal markers are unavailable or compromised. In practical terms, maxillary sinus morphology can support forensic experts when the pelvis or skull—considered the most reliable indicators of sex—are damaged, incomplete, or missing. For example, CBCT-based sinus dimension analysis has been applied to confirm sex identity in mass disaster victims and in cases of severe craniofacial trauma where conventional anthropological landmarks were not preserved. Furthermore, integrating sinus-based measurements with established skeletal indices has been shown to increase classification accuracy in forensic cases, providing a cross-validated approach when multiple markers are assessed together. Incorporating such complementary methods is particularly useful in medico-legal contexts, where even partial remains can yield reliable sex estimation when maxillary sinus morphology is included in the analysis.

Incorporating population-specific reference data, such as those provided here for a Saudi subpopulation, may enhance the accuracy of forensic identification and support medico-legal investigations.

Sinus size decreased progressively with age, particularly after 50 years. This trend may be linked to sinus wall thickening, bone remodelling, and loss of pneumatisation [31]. The largest widths were seen in the 41–50 year group, followed by a gradual decline. The effect of age on sinus size remains controversial. Some studies, such as Park et al. [32], have found that sinus dimensions increase up to the third decade and gradually reduce due to pneumatisation stabilisation and potential age-related bone remodelling. However, Aktuna Belgin et al. [33] noted minimal age-related changes, aligning with our non-significant age findings. Altındağ et al. [34] showed that sinus dimensions peak in young adulthood and decline with age, likely due to pneumatisation slowing, sinus wall thickening and tooth loss. Ramanathan et al. [35] reported age-related decreases in sinus height and volume in both male and female. Tiwari et al. [31] found that MS dimensions reduced with age, especially after the fifth decade of life, in an Indian cohort. From a clinical standpoint, the reduction in sinus volume and dimensions in older adults has direct implications for implant dentistry and sinus augmentation procedures. Smaller sinus cavities with thicker bony walls may initially appear favourable for implant stability due to increased bone density; however, limited vertical height and reduced pneumatisation can restrict implant length and complicate sinus lift procedures. Moreover, anatomical changes associated with ageing may increase the risk of Schneiderian membrane perforation during surgery. Therefore, careful CBCT evaluation in older patients is critical to determine implant feasibility, optimise grafting strategies, and reduce intraoperative complications.

Some side-related differences were observed in the dimensional characteristics of the MSs, indicating minor asymmetry. This finding is consistent with previous CBCT-based studies, such as Bayrak et al. [36], which have reported variations in sinus morphology between the right and left sides. Similarly, Przystańska et al. [37] suggested that such asymmetries may arise from developmental factors or environmental influences, with one side occasionally dominating in size. Conversely, studies by Motawei et al. [38] reported minimal asymmetry in sinus dimensions, and these differences were not statistically significant. Together, these findings highlight that although the MSs are generally bilaterally symmetrical, individual variations can occur. Therefore, each sinus must be assessed independently during surgical planning to ensure precise anatomical evaluation and minimise complications.

This study emphasises the value of CBCT imaging to identify sinus fluid, septa and membrane thickening before dental and surgical procedures, helping prevent complications. Sex- and age-related variations in sinus anatomy support the need for personalised treatment planning, especially in male and older patients. The findings also highlight the role of preventive care to reduce sinus pathology and serve as a valuable anatomical reference for education, clinical planning and population-specific research in the Saudi context.

Key findings from this study include: (i) sinus dimensions (width, length, area, and perimeter) were significantly larger in males than in females (p < 0.001); (ii) sinus size decreased progressively with age, particularly after the fifth decade of life; and (iii) sinus fluid was the most frequent abnormality, with higher prevalence in males and older individuals. Beyond their descriptive value, these findings have important clinical and forensic implications. In dentistry and maxillofacial surgery, awareness of sex- and age-related sinus variations is essential for safer surgical planning, implant placement, and sinus lift procedures, helping to minimize complications. In forensic contexts, dimensional differences of the maxillary sinus may serve as a reliable tool for sex estimation, supporting human identification when conventional markers are unavailable.

This study has several limitations. First, because the CBCT scans were obtained for specific dental procedures rather than screening of the general population, a degree of selection bias cannot be excluded, which may limit the representativeness of the sample. Second, although the sample size was large, the sex and age distribution may not fully reflect the general Saudi population, and this could affect the external validity of our findings. Third, the retrospective design precluded clinical correlation with symptomatology or patient history, limiting the ability to link anatomical variations with clinical outcomes. Finally, the cross-sectional nature of the study prevents causal inferences.

Conclusions

Under the limitations of this study, it could be concluded that this study emphasises a clear association between demographic factors (sex and age) and MS characteristics. Male and younger individuals tended to have larger sinus dimensions, while older adults showed a progressive reduction in size. Fluid accumulation and membrane thickening were more prevalent in male and older individuals, whereas sinus septa did not vary substantially by sex or age.

These findings highlight the diagnostic value of CBCT in the preoperative assessment of the posterior maxilla, where imaging is clinically justified to ensure tailored and safe surgical outcomes. Understanding these differences is vital for minimising complications in sinus-related dental procedures. Clinically, the high prevalence of sinus fluid underscores the need for careful radiographic evaluation before maxillary sinus–related surgical procedures, as unrecognized pathology may increase the risk of intraoperative complications. CBCT should be considered an essential tool in cases where detailed three-dimensional assessment of the maxillary sinus is indicated. Beyond clinical practice, these findings also provide valuable anatomical markers for sex estimation in forensic investigations, further underscoring their broader applicability. Future research should consider prospective designs with broader multi-regional population sampling and integration of clinical correlation to improve generalizability.

Author contributions

AAM and AFA contributed to the concept of the research, study design, data collection, supervision, statistical analysis, writing the original draft, and reading and editing the final paper. YEA, BBA, AYA, EAA, SHA, and KAK contributed to data collection and writing the original draft. Every author evaluated and approved the final manuscript.

Funding

declaration.

This research has been funded by Scientific Research Deanship at University of Ha'il-Saudi Arabia through project number <<RCP-25 033>>.

Data availability

Data is provided within the manuscript or supplementary information files.

Declarations

Ethics approval and consent participate

The Institutional Review Board (IRB) at Ha’il Health Cluster, Saudi Arabia approved the protocol of this study. Informed consent waived as the study retrospective. All methods were performed in accordance with the declaration of Helsinki.

Consent for publication

“Not Applicable”.

Competing interests

The authors declare no competing interests.