With 56 species on six continents (Antarctica excluded), it’s no wonder rats are recognizable to just about everyone. But what are rats’ teeth made of? And why do they have such a propensity for gnawing? Here, we’ll learn more about the fascinating teeth of these sometimes loved, sometimes hated, long tailed rodents. Then, we’ll go over common dental problems to watch out for in your pet rat, and how to prevent and treat them, should they arise.
What Kind of Teeth Do Rats Have?
Rats are monophyodonts, which means they only have one set of teeth for life. In contrast, humans have two sets of teeth; one set of ‘baby’ teeth, and one set of ‘adult’ teeth. Rats, like many rodents, have incisors that never stop growing. Unlike some of their relatives though, their molars have ‘true roots’, and grow only once in their lifetime–not continuously like their incisors. But not to worry; rat molars are extremely tough, and hard to wear out.
How Many Teeth Do Rats Have?
Rats have a total of 16 teeth; four incisors, and 12 molars. Unlike other animals, rats do not have a canine tooth. Instead, they have a gap called a diastema where the canine would normally sit. The jaws of most rodents share a similar, canine-less pattern.
Let’s learn a little more about what each type of tooth is used for, and what it looks like.
Rats’ incisors are located at the front of their mouth. They have two on top and two on bottom. When rats are born, these teeth are pearly white, but by the time they’re a couple months old, the incisors turn a bright yellow color. Not to worry though, yellow is a perfectly natural, healthy color for the teeth of older rats.
Rats use their incisors for one thing and one thing only; gnawing. Rats can gnaw through just about anything, and with incisors that grow at a rate of more than 2 millimeters per week, it’s no wonder. Rats have powerful jaw muscles to match their fearsome front teeth; the more a rat gnaws, the faster its incisors grow.
A healthy rat’s mouth should have bottom incisors that are about twice as long as the top incisors. The top and bottom incisors should meet and occlude (grind) against each other.
They may look like weapons, but rats only use their incisors to bite if they feel threatened or trapped.
The second type of tooth rats have is the molar. They have six on each side, with six on the top, and six on the bottom. These teeth are often called ‘cheek teeth’ because, in rodents, they are nearly identical to one another.
Molars are used to chew up the tough foods that rats subsist on. They are never used to gnaw, just like the incisors are never used to chew food. In fact, when a rat uses its incisors to gnaw, its molars never actually touch.
Unlike the incisors, which are ever-growing, rat molars have true roots (like human teeth) and only grow once, when the rat is young. Rats don’t generally have to worry about wearing out their cheek teeth though; they’re notoriously tough.
What Are Rat Teeth Made Of?
Rats have two types of teeth; the ever-growing incisors, and the more typical molars. The incisors have a thick layer of enamel coating that actually develops below the gumline–this is part of how the incisors stay in a constant state of growth, by continuously developing enamel below the surface. Below the enamel, the incisors are made of dentin, a much softer substance that forms the living part of the tooth.
Rat molars, however, are much more similar to human molars than are their incisors. The outside of the molar is made up of a layer of enamel which is thin on the sides and thick on the top. The enamel needs to be thick on the top of the tooth; this is the occlusal (chewing) surface, and wears down faster than any other part of the tooth.
Below the enamel is a second layer of slightly softer tooth material called cementum which protects the innermost part of the tooth–the dentin. The tooth’s dentin is the ‘root’ of the tooth–the living part. The dentin is filled with nerves and blood vessels, and keeps the tooth alive and healthy.
Like many rodents, rats are vulnerable to malocclusion (misalignment) and subsequent overgrowth. Unlike rodents like hamsters and rabbits though, whose cheek teeth are ever-growing and can become overgrown, rats’ cheek teeth are in no danger of overgrowth.
This leaves their incisors. Incisors can become overgrown through congenital defect, trauma (injury), or a lack of chewable items. When the top and bottom incisors don’t line up, they can’t grind against each other, and won’t wear each other down. Once this happens, the incisors rapidly become overgrown, making them difficult or even impossible for the rat to use.
If you suspect that your rat’s teeth are misaligned or overgrown, you should contact a vet who specializes in rodents. Depending on the severity of the issue, the vet may recommend either filing, cutting, or extracting the teeth. Never try to file or cut your rat’s teeth on your own, as they generally need to be sedated in order to safely trim their teeth. If a rat has incisors that grow in wrong, it may need to have frequent trimmings throughout its life, or even have the teeth extracted.
Preventing overgrown teeth in rats is easy; they just need enough stuff to chew. The best chewables are pet safe, non-toxic wood blocks. These can be found at any pet store, and should be given to your rat in abundance. Additionally, it’s important to feed your rat an appropriate diet to ensure it uses its cheek teeth correctly, and does not develop caries (cavities).
The photo featured at the top of this post is © daniiD/Shutterstock.com
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