Palatine rugae in the mouth

December 06, 2020

  

A look inside the oral cavity of a human reveals many important parts. The first ones to be distinguished are the teeth, tongue, the inner lining of the cheeks and the gingiva. The next thing someone can observe is the area below the tongue that is called the floor of the mouth. Apart from these structures, a layman won't appreciate any other structure with the naked eye. But there is one structure that is not much talked about and holds enormous importance. This is the palatine rugae.

The word rugae is derived from the Latin word 'ruga' which means a wrinkle or a crease. The roof of the mouth is called the palate and hence the name palatine rugae. The palatine rugae are located right behind the upper front teeth in the slope of the palate. It is seen as a structure with multiple wavy folds of tissue (the wrinkles). In this article we shall talk about the importance of this structure, the reason behind its uniqueness and how it is of prime importance to assess your dental health.

The location of the palatine rugae is such that it covers the anterior (front) 1/3rd of the palate. It will never reach the middle portion of the roof of the mouth. Right behind the center of the upper front teeth, a line extends the length of the palate dividing it into two halves. This structure is called the mix-palatine raphae. In the anterior region of the palate, on both sides of the mid-palatine raphae we see the folds of the rugae. These folds are seen as a result of a deflated tissue during development. The number, shape and size of the palatine rugae differ in each individual, making them an identification mark for each human just like thumbprints. Moreover, the left and right halves of the rugae are also never identical.

The number of rugae vary between three and five. These are usually curvy or angular. The last rugae in the pattern is likely to be divided and follows a more treacherous pattern. The growth of the rugae continues in a gradual manner for as long as 20 years. The measurement of the rugae determines the type of rugae. This length is measured from its origin near the mid-palatine raphae till the part that it extends to. The primary rugae are 5 mm in length, the secondary are 3 to 5 mm and the ones between 2-3 mm are tagged as fragmentary. The reason why we need to understand this is because from a clinical point of view, the dimensions can help us know about the abnormalities in the dental architecture. In order to better understand this, let us further proceed with the significance of having a folded, wrinkled structure right behind the upper front teeth.

As we saw earlier, the palatine rugae is unique in each individual. Moreover, its growth is slow and thus can serve as a reference point in analyzing the growth of the teeth that fall in its plane. This comes in handy when a patient opts for braces. Braces make significant change in the movements of the teeth and rugae can serve as good reference points to see the change in this movement.

The use of rugae as a reference point to analyze the movement of teeth is not restricted to the ones opting for braces. Dentists that are oriented to research might analyze the change in teeth movement during normal development at different age intervals. They might as well observe the change in the direction of growth rugae following an extraction of a tooth or teeth or after procedures that are likely to affect the structures responsible for tooth movement.

Palatine Rugae's other significance is highlighted in a developmental anomaly called cleft lip and cleft palate (CLCP). Just as the name suggests, the lip and the palate develop a depression that splits them apart. The repair of this defect takes time but most often gets resolved. When the split is seen in the palate, it is often observed that the rugae follows the notch or the depression. Before and after counts of the rugae after resolution of the defect has shown that the rugae count decreases. This is likely because, in the treatment of CLCP, appliances are wore by the patient that brings the two split ends of the palate together to close the notch. This can stretch the surrounding the tissues of the palate, thereby resulting in a decreased count.

Chronic smokers often complain of irritation or burning sensation in the palate. This is because the heat from the smoke is sensed by the palatine rugae which houses a rich nerve and blood supply. In the process, the palatine rugae is likely to be discolored in a greyish hue which might also give a hint of the extent of the person's smoking habits.

It is postulated that the palatal rugae also helps in speech. Sounds like "s" and "sh" are produced with vital role being played by the folds of the tissue. This is still difficult to ascertain as the thickness and shape of each tissue fold is different.

In patents requiring a denture, it is often seen that making the roof too smooth might lead to lisping (a form of improper speech). Attempts have been made to replicate the rugae on the denture but has not been too effective. This is because it would increase the thickness of the denture which would add to the discomfort of the patient.

The final and the most significant usage of palatine rugae is seen in forensic odontology. In cases of traumatic incidents like traffic accidents, burns, etc, palatine rugae has been used as an identification mark. Even though fingerprints and DNA analysis exist, they have their own shortcomings. Fingerprints might not be the best choice in burn victims whereas DNA analysis can be time-consuming and expensive. On the contrary, the palatine rugae is a well-protected area as it is covered by teeth, cheeks, lips, etc. It has been reported that in 93% of victims of third-degree burns, the palatine rugae was unharmed. Thus, palatine rugae is one of the most reliable techniques in identifying a victim.

Thus, the palatine rugae, which is difficult to appreciate at a first glance is one of the most important landmarks of the oral cavity.

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