A cross-sectional study

Background

The aim of this study was to evaluate the relationship between frontal sinus shape and facial growth pattern.

Methods

The three-dimensional examination was carried out by means of 80 CBCT scans selected from a sample of 1247 records of patients treated, for different reason, at the Department of Biomedical Surgical and Dental Sciences at University of Milan, Fondazione IRCCS Ca’ Granda, Ospedale Maggiore Policlinico Milan. The sample (age ranges between 12 and 40 years) was divided according to gender and age in four groups (12-17, 18-20, 21-30, 31-40). Left and right frontal sinus volume (VOL), surface (SUP) and linear maximum width (XMAX), depth (ZMAX) and height (YMAX) were calculated using Mimics Research 17.0 (Materialise N.V., Leuven, Belgium). Cephalometric analysis has been performed for all subjects to categorize the patients depending on their facial growth pattern. Univariate and multivariate regression analysis were performed to investigate any association of frontal sinuses measurements (height, width, depth, volume and surface) and cephalometric variables. P value < 0.05 was considered statistically significant.

Results

A total of 160 frontal sinuses were measures in 80 patients: 40 men and 40 women, average age of 23.5 ±14.6. Globally the frontal sinuses had the following average dimensions: volumes of 9055.8 ± 6505 mm³ and surfaces of 3820.3 ± 2125 mm². The statistical analysis showed that frontal sinus volume was statistically significant (p=0.003) greater for male (11,425 mm³) than female (6597.5 mm³). Similarly, the surface showed to be greater in men than in women (p=0.005). No correlation between age and frontal sinuses characteristics has been found. A statistically significant (p<0.05) increase of frontal sinus depth, surface and volume was correlated with SNB angle. In addition, frontal sinus volume increased in subjects with greater anterior skeletal dimension values and with a superior length of the cranial base. Furthermore, a decrease of ANB has been found related to an increase in frontal sinus volume (p=0.04).

Conclusions

The present study showed a correlation between frontal sinuses dimensions and craniofacial aspects, despite the inter-individual variability of their morphology. The results suggested that young adults in whom the frontal sinuses have reached their maximum size, while vertical growth continues, a larger frontal sinus may be associated with future vertical growth.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13005-022-00308-3.

First record of Troglotrema acutum (Trematoda, Troglotrematidae) in European polecats Mustela putorius from Luxembourg

We report the first record of the trematode Troglotrema acutum in skulls of European polecats (Mustela putorius) from Luxembourg. Thirty-one road-killed polecats from the northern and eastern parts of the country were examined. We found the trematode in three polecats from the administrative districts of Clervaux and Vianden in the northeast of the country. The parasites were detected in the frontal sinuses of one juvenile male as well as one adult of each sex. The animals were infected with six, nine and 13 adult trematodes, respectively, and we recovered 24 trematode eggs from one polecat. While the two adult hosts showed the lesions and deformations of the skull that are typical of T. acutum infections in polecats, the skull of the juvenile was not deformed. The prevalence of 9.7% reported here was lower than the values reported from Central European studies. Our findings indicate that the distribution range of T. acutum in western Central Europe extends to the Ardennes low mountain range.

Does the choice of the reference model affect the results of 3D-3D superimposition procedure? A comparison of different protocols for personal identification

In literature, 3D-3D superimposition has been widely recognized as a valid method for personal identification. However, very little information is available about possible variability due to differences in protocols of registration of 3D models and calculation of RMS (root mean square) point-to-point distance. Frontal sinuses from 50 CT scans were segmented twice through the ITK-SNAP software and grouped in two samples (1 and 2). Maximum breadth, height and volume were measured. 3D models belonging to the same subject were then superimposed one on each other in 50 matches. In addition, superimposition of 50 random mismatches was performed. For each superimposition, the procedure was repeated four times choosing different reference models both for registration and calculation of RMS. Differences in RMS value among protocols of registration and RMS calculation were assessed through paired Student's t-test (p < 0.05). Possible correlations between differences in RMS among groups and differences in frontal sinus size between the superimposed models were analysed through calculation of Pearson's correlation coefficient (p < 0.05). Results showed that RMS calculation did not yield significant differences according to which 3D model is used as reference; on the other hand, RMS values from registration procedure significantly differ according to which model is chosen as reference, but only in the mismatch group (p < 0.001). Differences in RMS value according to RMS calculation are dependent upon all the three measurements, whereas differences according to registration protocols were significantly related only with the breadth of frontal sinuses but only in mismatches (p < 0.001). In no case, superimpositions of RMS values were found between matches and mismatches. This article for the first time proves that the protocol of registration and calculation of RMS significantly influences the results of 3D-3D superimposition only in case of mismatches.

Frontal sinus: is it a predictor for vertical malocclusions?

The aim of the present study was to evaluate 3D frontal sinus morphology in consideration with different vertical facial developments. The study was conducted with the pre-treatment CBCT images of 87 patients, who were divided into 3 groups according to the sum of the posterior angle. The frontal sinus measurements were performed on the axial, sagittal, and coronal sections of the CBCT images. Craniofacial measurements were performed on the lateral cephalograms, obtained from the CBCT scans. Normal distribution of the data was confirmed by the Kolmogorov-Smirnov test. ANOVA, followed by post hoc Duncan tests, was used to compare the differences among the three groups. The relationships between sinus dimensions and craniofacial parameters were assessed by the Pearson's correlation coefficient (P < 0.05). The maximum anterior-posterior dimension of the frontal sinuses (0.017), the width of the right (0.020) and left (0.041) frontal sinuses, and the anterior-posterior dimension of the left (0.038) frontal sinus were significantly smaller in the hyperdivergent group compared to hypodivergent group. There was no significant difference between groups in terms of the height of the frontal sinuses. Significant correlation was noted between the maximum anterior-posterior dimension of the frontal sinus and SN-PP, N-Me, N-ANS, SN-GoGn, Post. sum, and Jarabak's ratio. No significant correlation between the height of the frontal sinuses and the craniofacial measurements was found. Individuals with vertical growth pattern presented decreased anterior-posterior dimension of the frontal sinuses, revealing significant correlations with vertical craniofacial parameters.

An innovative 3D-3D superimposition for assessing anatomical uniqueness of frontal sinuses through segmentation on CT scans

Anatomical uniqueness plays a significant role in the personal identification process of unknown deceased. Frontal sinuses have been widely used in the past decades for this purpose, mostly using 2D X-ray techniques. However, the modern 3D CT-based segmentation methods may help in developing novel and more reliable methods of identification. This study aims at assessing the anatomical uniqueness of frontal sinuses through the 3D model registration. Thirty subjects who underwent two maxillofacial CT scans (interval: 1 month to 5 years) were selected from a hospital database. Frontal sinuses were automatically segmented through ITK-SNAP open source software and the 3D models belonging to the same patient were automatically superimposed according to the least point-to-point difference between the two surfaces. Two hundred patients were randomly selected from the same database and undergo the same procedure to perform 200 superimpositions of frontal sinuses belonging to different individuals, equally divided between males and females (mismatches). Statistically significant differences of average root mean square (RMS) point-to-point distance between the group of matches and mismatches, as well as possible differences according to sex, were assessed through Mann-Whitney U test (p < 0.05). In the group of matches, RMS ranged between 0.07 and 0.96 mm (mean RMS 0.35 ± 0.23 mm), while in the group of mismatches, it ranged between 0.96 and 10.29 mm (mean RMS 2.59 ± 1.79 mm), with a statistically significant difference (p < 0.0001). Neither the matches nor the mismatches group showed statistically significant differences according to sex. This study proposes a novel 3D approach for the assessment of anatomical uniqueness of frontal sinuses, providing both morphological and quantitative analysis, and a new method of identification based on 3D assessment of frontal sinuses, applicable when ante-mortem CT scans are available.