Associations between the Volume of Bilateral Inferior Turbinates with Ipsilateral and Contralateral Sinus Mucosal Lining Thicknesses in Various Ages and Sexes: a CBCT Study of 302 Individuals.

Introduction: Rhinosinusitis is an important prevalent and bothersome problem relevant to dental specialties like maxillofacial surgery, pathology and radiology. Two main contributing factors to this problem are the inferior turbinate and sinus membrane. Except one flawed and incomplete preliminary study, no study has examined the potential link between the thickness of sinus mucosal lining and the volume of the inferior turbinate. Besides, the role of gender and aging on turbinate volume or sinus membrane thickness is not assessed, except in one or two studies. Therefore, this large study was conducted.

Methods: This cross-sectional study was performed on 604 right and left turbinates and sinuses in 302 patients (154 males, 184 females; mean age 30.14 ± 9.44 years). This sample size was deemed about 12 times larger than the size necessary for high powers. Archival CBCTs were screened for cases with bilateral maxillary sinuses and turbinates. The thickness of their sinus membranes was measured on six points on each side and the greatest one was recorded in millimeters (mm). Their inferior turbinates were segmented manually and their volumes were measured in cm³ using a computer program set at the threshold range of 0-300 HU. Sinus membranes 1.0 mm thick or thicker were considered mucositis. The associations among turbinate volume, the occurrence of turbinate hypertrophy, sinus mucosal membrane, sinus mucositis occurrence and patients' age and sex were examined using the multiple linear regression, partial correlation coefficient controlling for sex, Pearson correlation coefficient, chi-squared and paired and unpaired t-tests (α = 0.05).

Results: The sample was balanced in terms of sex and age (P = 0.102). The mean (SD) for the right turbinate volume, left turbinate volume, right mucosa thickness, left mucosa thickness, average turbinate volume and average mucosa thickness were 6.223 ± 1.404 cm³, 6.256 ± 1.811 cm³, 1.918 ± 3.777 mm, 2.501 ± 4.793 mm, 6.239 ± 1.236 cm³ and 2.209 ± 3.690 mm, respectively. The volume of each turbinate was correlated with the mucosal thickness of the ipsilateral and contralateral sinuses (R values ranging between 0.351 and 0.459, all P values = 0.000). The correlation between average turbinate volume and average mucosa thickness was 62.8% (P = 0.000). Age was not correlated with any of the anatomic measurements. Multiple regression identified both left/right sinus membrane thicknesses as predictors of turbinate volume (P < 0.003); sex (but not age) was the predictor for the left and average turbinates (P < 0.05). Turbinates were larger in men; mucosae were thicker in men (all P values < 0.05). The volumes of turbinates were similar on the right and left sides (P = 0.789); however, sinus membranes were significantly thicker on the left side compared to the right (P = 0.024).

Conclusions: The inferior turbinate volume may be associated with the thickness of both ipsilateral and contralateral sinus membranes. The male sex is associated with thicker mucosa linings and larger turbinates. Aging might not affect turbinate volume or sinus mucosa thickness.