Skip to content
PawLabel
Sign in
anatomy guide

Rat dental anatomy — continuously growing incisors and rooted molars

Overview of rat dentition — sixteen teeth, elodont incisors with enamel only on the front surface, a long diastema, and rooted molars that stop growing once they have erupted.
General educational reference only — not clinical or veterinary advice. Anatomy varies between individual animals; consult a licensed veterinarian for any health concern.

Sixteen teeth and a long diastema

A rat has sixteen teeth: one pair of incisors and three molars in each quadrant, written 2 × (I 1/1, C 0/0, P 0/0, M 3/3). There are no canines and no premolars, leaving a long toothless gap, the diastema, between the incisors and the molar rows. Folds of cheek and lip skin can be drawn inward across this gap, closing the mouth off behind the incisors while material is gnawed.

Incisors that never stop growing

The incisors are aradicular hypsodont, or elodont: they have no closed root, keep a permanently open apex and grow throughout life. Enamel is laid down only on the labial surface and is pigmented yellow-orange; the lingual side is softer dentine. The two wear at different rates as the teeth work against each other, so the tip is continuously reshaped into a beveled chisel edge. The lower incisors are the longer pair, their growing apices lying deep within the mandible.

Rooted molars and two jaw positions

Unlike the incisors, and unlike the cheek teeth of chinchillas and guinea pigs, rat molars are brachydont and rooted: they erupt in the first weeks of life, close their apices and then grow no further. Their occlusal surfaces bear rows of cusps for grinding. The mandible must be positioned differently for each set — drawn forward so the incisor tips meet for gnawing, and pulled back so the molars occlude for chewing — so the two actions cannot happen at once.

Sources

Other species

Dog digestive system — anatomy overviewDog skeletal system — anatomy overviewDog cardiovascular system — anatomy overviewDog respiratory system — anatomy overviewDog urinary system — anatomy overviewDog integumentary system — skin and coat anatomy overviewDog nervous system — anatomy overviewDog dental anatomy — teeth overviewCat digestive system — anatomy overviewCat skeletal system — anatomy overviewCat cardiovascular system — anatomy overviewCat respiratory system — anatomy overviewCat urinary system — anatomy overviewCat integumentary system — skin and coat anatomy overviewCat dental anatomy — teeth overviewRabbit digestive system — hindgut fermentation and cecotrophyRabbit dental anatomy — continuously growing (elodont) teethRabbit skeletal system — lightweight bones and a fragile spineFerret digestive system — short-gut obligate carnivoreFerret respiratory system — anatomy overviewGuinea pig digestive system — hindgut fermenter with vitamin-C dependenceGuinea pig dental anatomy — open-rooted, continuously growing teethParrot respiratory system — air sacs and flow-through lungsParrot digestive system — crop, gizzard, and cloacaParrot skeletal system — pneumatic bones and a flight frameBearded dragon digestive system — anatomy overviewBearded dragon skeletal system — anatomy overviewBearded dragon thermoregulation — ectothermy and skinSnake digestive system — a highly distensible carnivore gutSnake skeletal system — vertebrae and ribsTortoise skeletal system — carapace, plastron, and fused ribsTortoise digestive system — beak, gut, and hindgut fermentationBearded dragon respiratory system — glottis, trachea, and faveolar lungsParrot urinary system — avian kidneys, ureters, and uric acidLeopard gecko digestive system — an insectivore's gutParrot cardiovascular system — avian heart and circulationTurtle skeletal system — shell, girdles, and neck retractionBearded dragon dental anatomy — acrodont and pleurodont teethSnake respiratory system — glottis, tracheal lung, and one functional lungLeopard gecko skeletal system — limbs and tail autotomyAxolotl respiratory system — external gills, lungs, and skinHorse digestive system — hindgut fermenter with a large colonSnake integumentary system — scales, ecdysis, and the spectacleTortoise respiratory system — breathing inside a rigid shellBetta respiratory system — gills and the labyrinth organGoldfish digestive system — pharyngeal teeth and no true stomachGoldfish respiratory system — gill arches, lamellae, and countercurrent exchangeParrot integumentary system — feathers, tracts, and the preen glandSnake cardiovascular system — a three-chambered heart along the bodyLeopard gecko integumentary system — skin, shedding, and toes without padsChinchilla dental anatomy — elodont teeth and continuous eruptionChinchilla digestive system — a sacculated cecum and an exceptionally long colonAfrican pygmy hedgehog integumentary system — spines, mantle, and the orbicularis muscle

Explore

All anatomy guidesToxic foods & substancesPet-food allergens