**7. Diagnostic aids in detection of the potentially malignant disorders of the oral and maxillofacial region**

Development of cancers and cancer-related death and negative health impacts can be reduced effectively and efficiently by early identification and treatment of premalignant disorders that have a high risk of developing into cancers [29]. This proactive strategy not only helps in detecting cancer at its earliest stages but also allows for interventions that can prevent or delay the progression of these lesions into invasive cancer. Oral lesions are early indications of oral cancer and lesions exhibiting dysplastic characteristics fall under the classification of oral potentially malignant disorders (OPMDs) [22, 59]. These OPMDs include oral leukoplakia, erythroplakia, oral submucous fibrosis (OSF), proliferative verrucous leukoplakia, and oral lichen planus [22, 25, 30], which are considered to carry a significant risk of developing into malignancy [22]. Indeed, conventional oral examination (COE) alone may have limitations when it comes to diagnosing potentially malignant disorders in the oral cavity. However, in recent years, several cutting-edge techniques and advancements in technology have been introduced to overcome these limitations (**Figure 2**).

Biopsy as a histological examination remains the gold standard for diagnosing oral potentially malignant disorders (OPMDs) [25, 30]. This traditional method involves the surgical removal of a small tissue sample from the suspicious area, which is then examined under a microscope by a pathologist to determine if any abnormal cellular changes or potentially malignant features are present. However, in recent decades, more advanced and less invasive techniques in oral cytology have been proposed as alternative methods for the diagnosis and follow-up of OPMDs. Two notable modern methods are brush biopsy and microbiopsy [30].

At present time, fluorescent technologies are broadly used in potentially malignant diagnosis. Ionic imbalance, abnormal nucleus or high ratios of nucleus/cytoplasm, unnecessary infiltrated inflammation, etc. are the indications of the abnormal mucosal lesion. During the process of examining tissues under chemiluminescent illumination, those abnormal mucosal lesions seen as aceto-white, but healthy normal mucosa display a dark blue color [59]. This difference in appearance is due to variations in how light is scattered back from the tissue between normal mucosa and abnormal lesions. Autofluorescence imaging is another fluorescent technology for potentially malignant lesion diagnosis [30]. This technology uses blue light whose wavelength is 400–460 nm [58]. When blue light is applied to tissues, normal healthy tissue displays

#### **Figure 2.**

*Diagnostic aids for the detection of malignant transformation capacity of the potentially malignant disorders of the oral and maxillofacial region.*

apple green fluorescence whose wavelength is 510 nm, while malignant lesions do not show any color (loss of autofluorescence) [59].

Imaging techniques offer additional information to physicians and can assist in planning more effective treatment strategies. In recent years, an innovative category of optical imaging technologies called *in vivo* microscopy (IVM) has emerged, offering great potential as a diagnostic tool for OPMDs. IVM works by capturing images of minute tissue characteristics through the measurement of tissue optical properties, including reflectance, scattering, absorption, and fluorescence emission. These properties often undergo changes in various disease conditions [25]. The application of IVM has shown promise in the early detection of oral potentially malignant disorders (OPMDs), although the assessment of this method is still in its preliminary stages. Multimodal imaging, optical coherence tomography, reflectance confocal microscopy, and multiphoton microscopy are some examples of IVM.

There are many clinical tissues staining technique for potentially malignant disorders diagnosis; among them toluidine blue, a cationic metachromatic dye is the most common [30]. Toluidine blue is a diagnostic adjunct that can be employed for the early detection of oral squamous cell carcinoma [60, 61]. Toluidine blue has a higher affinity for DNA and RNA, and since malignant lesions contain more DNA and RNA components, they tend to exhibit a greater uptake of the stain [60]. Toluidine blue stained areas of the dysplastic epithelium look royal blue [30]. In a study, the sensitivity of toluidine blue in detecting malignant and potentially malignant lesions was found to be 88.89% [60]. This technique not only aids in the detection of early dysplastic lesions but also assists in determining the appropriate site for biopsy [60].

#### *Genetic Revelation of the Potentially Malignant Disorders in the Oral and Maxillofacial… DOI: http://dx.doi.org/10.5772/intechopen.112697*

Furthermore, the method is simple, noninvasive, and can be performed chair-side with a good level of diagnostic accuracy [61]. Vital iodine staining is also effective for detecting potentially malignant and malignant lesions of the oral mucosa [62].

Dysplasia is the most well-established marker but non-obligate precursors of oral squamous cell carcinoma (OSCC) [25]. Phenotypic changes in molecular markers can serve as valuable indicators for evaluating the cancer risk associated with oral potentially malignant disorders (OPMDs). These markers encompass both genetic and protein-based indicators [29]. In the context of OPMD diagnosis, stem cell selfrenewal factors can be regarded as biomarkers since there are numerous shared characteristics between stem cells and cancer cells [29]. Some notable protein markers include β-catenin, cyclooxygenase 2 (COX2), c-Met, carbonic anhydrase 9 (CA9), Podoplanin, Ki-67, p16, p53, IMP3, c-Jun, SNAI1 (snail family transcriptional repressor 1), AXIN2 (axin 2), SMAD4 (SMAD family member 4), Notch1, ATM (ATM serine/threonine kinase), yH2AFX, nucleostemin (NS), SOX2 (SRY-box transcription factor 2), ALDH1, and NANOG (Nanoghomeobox), MAGE-A (MAGE family member A), cortactin, FAK (protein tyrosine kinase 2), loss of heterozygosity (LOH), Methyltransferase-Like 3 (METTL3) salivary exosomal microRNAs, etc., all of which have demonstrated potential as risk-predictive markers for OPMDs [29, 63, 64]. The abnormal alterations in the levels of these markers can be indicative of the presence of oral potentially malignant disorders (OPMDs), and the examination of those biomarkers helps to detect oral potentially malignant disorders.

Metabolic phenotypes exhibited notable distinctions between individuals with cancer and those without, indicating a promising avenue for identifying biomarkers associated with various diseases. Metabolic analysis has shown remarkable efficacy in the detection of potentially malignant disorders within the oral cavity [42]. Oral lichen planus (OLP) is classified as an oral potentially malignant disorder. A study utilizing metabolic analysis identified 21 metabolites and eight signaling pathways, which have the potential to serve as biomarkers for OLP [53]. In another study, a biomarker panel composed of Glutamic acid, LysoPE (18:0), and taurine achieved an accuracy of 87.1% in detecting OLP [42]. The researchers employed ultra-performance liquid chromatography-quadrupole/orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) for this detection method.
