Supervisors info:
Σπύρος Δαμάσκος, Επίκουρος Καθηγητής, Τμήμα Οδοντιατρικής, Σχολή Επιστημών Υγείας, ΕΚΠΑ
Κωνσταντίνος Τσιχλάκης, Καθηγητής, Τμήμα Οδοντιατρικής, Σχολή Επιστημών Υγείας, ΕΚΠΑ
Στεφανιώτης Θεόδωρος, Επίκουρος Καθηγητής, Τμήμα Οδοντιατρικής, Σχολή Επιστημών Υγείας, ΕΚΠΑ
Summary:
Objectives: The purpose of this study is twofold: α) to determine the relative position of the distribution of ―"calcifications" in various anatomical regions within the parenchyma and the ductal system of parotid gland (PG) using panoramic radiographs (PR) performed in four different focal troughs, and b) to investigate the possibility of differentiating those calcifications from similar structures resembling "tonsiloliths" due to the above used imaging technique. Their exact allocation was determined using cone beam CT (CBCT) as gold standard.
Study Design A model, based on human dry skull was created. On it, the majority of the cranial muscles (e.g.: masseters, lateral and medial pterygoids, buccinators, etc. as well as the tongue) were reconstructed by using dental red wax (Tenatex Red, Toughened Dental Modelling Wax), according to their relative anatomical position and size. Subsequently, the major salivary glands (parotid, submandibular and sublingual) and parsley tonsils were re-created, also on their anatomical position and size, by using hard putty impression material (Speedex, Coltene). To resemble the presence of "calcifications", radiopaque materials (ANA 2000, Nordiska Dental) of different shape and size were inserted into the "gland's parenchyma" and tonsil‘s. Subsequently, the model underwent PR examinations in four different focal trough positions and CBCT. The evaluation of the imaging sites of the radiopaque materials in the PR was determined on the basis of the three-dimensional imaging data obtained from CBCT.
Results All the measurements obtained from the four (4) PRs‘ tomographic zones do not match those of CBCTs. The measurements of the tomographic zones 1 & 2 shows that there is an agreement among them and that they are also closer to the real ones. The measurements of tomography zones 3 & 4 are unreliable. The statistical methodology used to compare the two imaging modalities to each other was Bland-Altman. The data were analyzed using IBM SPSS v.25 and MedCalc v.18.9.
Conclusions: : 1. The presence of "calcified structures" on the deep lobe of the PG is not represented in the PR in any of the investigated tomographic zones (1, 2, 3 and 4). 2. In PR, and in the tomographic zones 1 and 2, the positions of the "calcifications" depicted in the superior part of the PG's superficial lobe are more closely related to the actual CBCT measurements. This condition applies when the measurements are performed from the center of the left mandibular notch. 3. Accordingly, the relative positions of the "calcifications" depicted in the middle and posterior part of the PG‘s superficial pole – as displayed in the tomographic zones 1 and 2 - show an even greater degree of correlation, in absolute values, with actual CBCT measurements. This is the case when the measurements are carried out from the center of the left mandibular notch. 4. In PR, and in the tomographic zones 1, 2 and 3, the relative position of the radiopaque material depicted in the course of the Stensen‘s duct is more closely related to actual CBCT measurements, provided, that the measurements are performed from the mandibular angle. 5. The relative position of the "tonsiloliths", as depicted in PR, is not clearly correlated with actual CBCT measurements, particularly in tomographic zones 3 and 4. 6. The most adequate tomographic zones for imaging "calcifications" in the PG‘s salivary complex are 1 and 2, but, without knowing which of the two is the most appropriate each time. 7. In PR, the measurements of the tomographic zones 3 and 4 diverged - with enormous difference - from those of CBCT. This can be attributed to the positioning of the anatomical structures within the aforementioned tomographic zones. In particular, the measurements of the tomographic zone 4 are totally unreliable compared to those of CBCT (gold standard). 8. The results of our measurements are related to the selection of the most appropriate tomographic zone in PR. This is always in relation to the individual anatomy of each patient‘s skull, as well as its correct placement within the selected focal trough. This determines the location where the anatomical structures of the area of interest are accurately projected.
Keywords:
Calcifications, Imaging area, Parotid gland salivary complex, Panoramic radiography, CBCT
