Discussion
precancerous lesions, hyperplasia, trauma, OPMDs, OLP ulcer, dysplasia, hyper-keratosis, microinvasive carcinoma, hyper-parakeratosis, OPMD, malignity, OSCC, PVL
PRECANCEROUS LESIONS, HYPERPLASIA, PROLIFERATION, OPMDS, DYSPLASIA, ULCERS, MICROINVASIVE CARCINOMA, LEUKOPLAKIA, ORAL CANCER
The ability of OCT to distinguish between precancerous lesions and oral cancer is still unclear. A recent study calculated a sensitivity (93–96%) and specificity (74–49%) in ex-vivo OSCC, leukoplakia with hyperplasia and healthy simple tissue by creating computational models of these tissues and employing an artificial neural network analysis algorithm [Another recent meta-analysis reported the trend of OCT in OPMDs to be less sensitive (0.8960) and specific (0.8962) than OSCC (0.9316) [The possible explanation for this result lies in the absence of systematic reviews that analyzed only the OCT patterns only for OPMDs, in the lack of standardization of instrument settings and image measurement methods for the universal use of data. However, the generally high sensitivity and specificity indicate the potential utility of OCT for OPMD follow-up.The use of artificial intelligence will be the real upgrade of use of OCT in Oral Medicine [Currently, the main limitations of this procedure depend on both the device and the operator. The first concerns the device itself, i.e. the limited diffusion of OCT in the dental field with high-performance intraoral OCT handheld probes and the limited imaging depth [Knowledge of OCT healthy tissue is essential for understanding ultrastructural alterations [In the healthy tissue, the EP layer is always hypo-reflective (with the exception of the superficial KL, if it is present), the LP is always hyper-reflective with an internal non-reflective areas; the difference between these two degrees of reflectance leads to estimate the position of the BM.The data of this study are broadly in agreement with the study of Albrecht et al. [Furthermore, the authors affirm that it is possible to identify large vascular structures in the structure of the lamina propria: also, this data is in agreement with our evidence. The same author argues that it is difficult to highlight the basal membrane in the region of the ventral tongue, while we were able to clearly identify it. This could be due to the different position of the intraoral probe: in our study the probe was brought into contact with the mucosa.According to some authors, the hyper-reflectance of the epithelial layer can be understood as a good parameter to differentiate diseased tissues from healthy ones [The site-specificity in which the lesions appear is the first step in being able to identify the pathological tissue from the healthy one.Panzarella et al. [The same authors highlight how in dorsum tongue there is no real difference in reflectance that allows us to distinguish KL from EP, therefore the anatomy is not the same as other structures that appear flat.Although the investigated sites are dissimilar, the common aspects of all the OPMDs analyzed were two: increase in epithelial reflectance and decrease in reflectance of the lamina propria [For this reason, ulcers patterns could highlight a superficial hyper-reflectance because epithelial cells increase proliferation starting from the edges of the lesion to try to re-epithelialize the area. In extensive ulcers also the central fibrin panniculus could result in greater reflectance, but this data should be further investigated. The presence of hyper-reflectance area in the residual epithelium of an OLP ulcer is due to a mild hyper-keratosis or hyper-parakeratosis but the loss of the clear difference between the two reflectance degrees (between epithelial and connective tissue) makes it difficult to identify the basal membrane [It is almost established that the more the lesions evolve towards malignity, the less the layers and the basal membrane are identifiable [The loss of the clear difference between the two reflectance degrees (between epithelial and connective tissue) makes it difficult to identify the basal membrane: the lesions for which it was more difficult to identify the basal membrane were those affecting the buccal mucosa, the adherent gingiva, the border and the ventral tongue.Specifically, it is difficult to identify the basal membrane in: OLP ulcers on the edge of the tongue, ventral tongue and buccal mucosa, spot on the buccal mucosa due to OLP, inhomogeneous white/red lesion on adherent gingiva (K-MICRO) and PVL on adherent gingiva. From the analysis of our images it was possible to notice a characteristic aspect of OLP ulcers: the almost total loss of the epithelial component and a uniform LP hypo-reflectivity of the connective component. This makes it very difficult to estimate the position of the basal membrane. In trauma ulcers, this specific pattern appears not to occur so frequently [A white lesion does not always clinically correspond to an increased epithelial tissue thickness. Even if we are considering keratinized lesions, it is not always possible to assess a KL, because often the keratinization process involves the entire thickness of EP and not only the superficial layer. For this reason, withe lesions on the tissue surface can lead to a decrease in the depth of light penetration, effectively limiting the potential of the OCT system.We conducted our in vivo investigation on different types of lesions without preliminarily knowing the result of the initial histopathological analysis. In our series, an inhomogeneous white-red lesion turned out to be a microinvasive carcinoma and the OCT pattern already describes the typical peculiarities of invasive oral cancer such as the non-determinability of the basement membrane [Although this study did not investigate the possibility of recognizing the presence of dysplasia using the OCT system, it is suggested that dysplasia is also present in perilesional clinically healthy tissue [