Rats’ teeth are designed for gnawing. Rats gnaw relentlessly to keep their teeth filed and prevent them from growing out of proportion.
To understand why rat teeth are so strong, we need to look at their dental anatomy.
Rats have 16 teeth: 4 incisors for gnawing, with 2 incisors on the upper jaw and 2 on the bottom jaw. Rats also have 12 molars whose function is to break down food into tiny chunks that are easy to swallow.
Rats don’t have premolars, as their jaws have a space known as a diastema.
Gnawing allows rats to keep their teeth sharp and gives the incisors their characteristic curved appearance. Only the outer layer of a rat’s incisors is coated in a hard yellow enamel.
Therefore, when the rat gnaws, the inside part of their incisors wears away faster than the outside, giving them a curved appearance.
As mentioned, rats only have 16 teeth, comprised of 4 incisors and 12 molars. The incisors are located at the front part of a rat’s mouth, with 2 on each jaw. The incisors are primarily used for gnawing.
According to the Journal of the American Association of Laboratory Animal Science, rats’ incisors don’t have roots, so they never stop growing.
Rodents grind them on hard surfaces to keep these teeth from growing out of proportion.
The molars, which are distributed in three pairs on each jaw, are used for pulverizing food to make it easier to swallow.
Rats have a space (known as a diastema) between the incisors and molars on each jaw. This enables rats to fill it with their cheeks to allow inedible material to fall out of their mouths when chewing.
Rats don’t have canine teeth.
Rats have a space on each side of their mouths between their incisors and molars. This allows rats to suck in their cheeks when chewing to prevent non-edible material from entering their throats.
What Are Rat’s Teeth Made Of?
The outer parts of a rat’s teeth are enamel, while the inner section is soft dentine. As a rat gnaws, the incisors on their top and bottom jaws grind against each other.
This causes the dentine to wear away faster than the enamel. That is what gives rat incisors their characteristically curved appearance, despite not being curved.
Why Are Rats’ Teeth So Strong?
While rat teeth are small in size, they’re very tough. They’re capable of chewing through some of the hardest materials, including wood, metals, and certain types of concrete.
The Mohs scale ranks rat teeth higher than human teeth in terms of toughness.
While human teeth rank 5.0 on this scale, rat teeth are ranked at 5.5. This explains why rats can cause so much damage to property with their relentless gnawing once they get inside your home.
Rats can deliver strong bites while gnawing due to the musculature of their jaws. The attachment point of the muscles in their lower jaws moves forward toward the nose than in humans and other mammals.
Moreover, the muscles attached to the lower jaw are anchored in the eye sockets just behind the eyeballs. This is why a rat’s eyeballs will vibrate in and out as they chew.
According to Exotic Animal Practice, rats have monophyodont teeth.
In other words, they only have one set of teeth that continuously grow throughout their lives. So, a rat’s teeth will grow back as long as they aren’t knocked out or broken due to an accident.
If a rat loses the teeth from its upper jaw, the teeth on its lower jaw will continue to grow even while the upper teeth are missing. This means it’ll need to be trimmed until the new set of upper teeth grows.
After which, it’ll be able to grind its teeth together to keep them in shape.
As mentioned, rat teeth don’t have roots, so they continuously grow throughout their lives. This is useful in an evolutionary sense since it allows the rodents to gnaw and chew food for sustenance.
However, the lifelong growth of a rat’s teeth also presents problems.
Overgrown teeth can make it difficult for them to eat properly. Furthermore, if a tooth is allowed to grow unchecked, it can tilt at an odd angle, piercing their mouths, and causing injury and infection.
An overgrown tooth can cause death if it grows long enough to puncture the brain.
To keep this from happening, rats will constantly grind their teeth to wear them down. This not only prevents overgrowth but also keeps the teeth sharp.
Rats wear down and renew their teeth every 40-50 days.
Rats have a unique dental anatomy that sets them apart from other mammals.
Here are some interesting facts about rats’ teeth:
A rat’s front teeth are open-rooted, and that’s why they continuously grow throughout their lives. Rats’ incisors are estimated to grow 4-5 inches each year.
However, rats won’t allow their teeth to grow out of control, making it difficult or impossible for them to eat and survive. Instead, they constantly gnaw and grind their teeth to wear them down.
It’s estimated that rats renew their front teeth every 40-50 days.
Rats’ Teeth Can Grow Back After Falling Off
Rats can regenerate their front teeth if they lose them in an accident. The remaining teeth will continue to grow even when the rest are missing.
Rats need to grind their remaining teeth on hard surfaces to keep them trimmed as the new front teeth grow.
Rats’ Teeth are Harder Than Human Teeth
According to the Mohs scale, which ranks minerals in their order of toughness from least to most hard, rats’ teeth are significantly tougher than human teeth and even some types of metal.
This scale gives rats’ teeth a ranking of 5.5. By contrast, human teeth have a ranking of 5.0.
Considering this, it shouldn’t come as a surprise that rats can gnaw through some of the toughest materials, including aluminum, iron, copper, cinder blocks, glass, and wood.