Like fingerprints, every person’s tongue has a unique print that sets them apart. This little-known fact has sparked interest in the scientific community, with researchers exploring the potential applications of tongue prints in fields like forensics and biometrics. But what makes tongue prints so unique, and how can they be used to identify individuals? Let’s delve into the fascinating world of tongue prints and uncover their secrets.
An overview
Tongue is a vital internal organ well encased within the oral cavity and protected from the environment. It has unique features which differ from individual to individual and even between identical twins. The color, shape, and surface features are characteristic of every individual, and this serves as a tool for identification.
Many modes of biometric systems have come into existence such as fingerprint, iris scan, skin color, signature verification, voice recognition, and face recognition. The search for a new personal identification method secure has led to the use of the lingual impression or the tongue print as a method of biometric authentication.
Tongue characteristics exhibit sexual dimorphism thus aiding in the identification of the person. Emerging as a novel biometric tool, tongue prints also hold the promise of a potential forensic tool. This review highlights the uniqueness of tongue prints and its superiority over other biometric identification systems. The various methods of tongue print collection and the classification of tongue features are also elucidated.
Uniqueness of Tongue
Tongue is a vital organ, and its vitality is described in Traditional Chinese Medicine (TCM) as “Tongue of life” where the tongue has a vital color. In contrast, the “Tongue of death” in TCM is termed so due to its dark and withered appearance.
Its uniqueness is further showcased by the fact that since it is an internal organ, it is a proof of life that is whether the person is alive or dead. Only when a person is alive can they protrude the tongue for examination purposes.
Many a times, death occurs when the tongue falls back to obstruct the airway, especially in cases of sleep apnea. Second, the analysis of shape, texture, and color reveals visible differences between one individual and another thereby making it a useful tool in personal identification. It conveys a lot of information regarding the health status of an individual. Hence, it has been commonly studied and evaluated in TCM.
The tongue like any other organ has its share of skeletal muscles, blood vessels, and nerve supply. In addition, it is bestowed with papillae and taste buds. In TCM, it has been observed and stated that the general texture of the tongue varies between individuals and since it is affected by diseases, it can be a useful tool in identifying medical conditions. Simple visual comparison can indicate clear differences.
Tongue Print Versus Other Biometric Systems
The different biometric systems that are employed for security purposes are fingerprint, retinal scan, skin color, voice check, palm print, face scan, signature check, etc. Each of these systems has their own advantages and disadvantages. The disadvantages for each system make it vulnerable for security breach and also a hassle in identification purposes.
Fingerprints can be eroded, changed due to work, altered by surgery, and subjected to injuries and burns, so they are not stable. When voice is considered, it is affected by sicknesses such as cold and coughs. In the case of extreme emotional states, there are chances of misspoken words. Retinal scan is highly sensitive.
It is dependent on the user and can be affected by bright light and diseases such as cataract and astigmatism. Skin color is also one type of biometric system, but it presents with stability problems as considerable differences are seen with age, burns, diseases, and use of skin creams or medications.
Numerous advantages exist in using tongue print over other biometric systems such as fingerprint, voice check, and retinal scan. The tongue is unique to every person concerning its shape and surface textures. Since it is an internal organ, it can be easily exposed for inspection and the exposed surface carries the required information. The physiological texture and shape remain constant.
It is well protected from the external environment, and so it is not affected by external factors. It is also a reliable proof of life. In recent years, tongue print is gaining momentum as an important tool in biometric authentication.
How to Identify Tongue Prints and its Collection
Tongue prints can be obtained in different ways. A simple visual inspection of the tongue reveals many features such as the color of the tongue, mobility, surface textural variations, and any other special characteristics if present. Digital photographs of the tongue can be captured and matched with a database for verification.
They can also be used to identify the shape of the tongue. The shape of the tongue is obtained by joining three reference points. A study carried out at Hong Kong Polytechnic University in 2007, was designed to develop a tongue image database, which included both tongue geometric shapes and surface textures of individuals, and this database was assumed to be a valuable resource for assessment, comparison, and evaluation.
Three-dimensional analysis of the tongue is a viable option for assessment. Analysis of the tongue can be performed by taking an alginate impression followed by cast preparation. This helps in capturing the unique features and reproducing them onto a cast which can be used for study purposes.
Digital software has been formulated that autocorrects for the color and hue along with the positional alterations and camera conditions and then analyses the tongue for its color and texture to match with its database to bring about identification.
Many studies have been researched to prepare a proper algorithm for tongue image analysis. Other methods tried are capturing the video of a tongue and extracting images from the same as the tongue is a non-rigid organ.
The alternate method includes sublingual vein analysis, which is one of the common methods employed in tongue diagnosis. An ultrasound technique has been employed using an ultrasound transducer placed in the sublingual area to analyze the tongue function. Histological examination of the tongue can also be undertaken.
