Anatomy of rabbit teeth
Dale Kressin, DVM, FAVD, Dipl. AVDC
With the gracious permission of Dr. D. Kressin to reproduce in MediRabbit.com
The incisors and cheek teeth of rabbits are called aradicular hypsodont (high-crowned teeth and enamel which extends past the gum line) teeth. This is sometimes referred to as an elodent dentition. These teeth grow or erupt continuously. The growth or eruption is held in balance by dental abrasion from chewing a diet high in fiber.
Familiarity with the incisor anatomy is important if the veterinarian is considering extraction of these teeth. The upper incisors are paired teeth on the left and right sides. The front incisor is larger than the distal smaller (peg) tooth. The larger incisor is in the formation of a half circle. The vestibular aspect of these incisors have a deep developmental groove. The smaller peg incisor has a broader curvature and is roughly half as long as the larger incisor. The mandibular incisor is longer than the anterior upper incisor and its curvature is broader. The apical end of the mandibular incisor is orientated lingual to the first mandibular cheek tooth (premolar).
Why would I take the time to discuss the anatomy of the cheek teeth?
I believe an understanding of this dental anatomy is critical to performing occlusal adjustments effectively. Understanding the normal anatomy allows the veterinarian to recreate near normal anatomic dental arch relationships by properly performing occlusal adjustment.
The teeth of the rabbit are heterodont and diphydont.
Heterodont teeth are simply teeth of different types as opposed to teeth of the same type, called homodont. Rabbits have incisor teeth and cheek teeth. The cheek teeth include both premolars and molars. Rabbits do not have canine teeth as in cats, dogs, ferrets and hedgehogs. Rabbits have a diphydont dentition since they have deciduous (primary) and secondary (adult) teeth.
Anatomic Dental Formula
2(i2/1 c0/0 m3/2)= 16 deciduous teeth
2(I2/1 C0/0 P3/2 M3/3)= 28 permanent teeth
Cheek teeth occlusion
There is a clear jaw width disparity when viewing the cheek teeth from an occlusal view. The upper and lower jaw relationship is anisognathic. The mandibular dental arch consists of premolars and molars orientated in a straight line. The upper dental arch (maxillary) consists of premolars arranged in a lateral convex curved orientation. The dental arches have a slightly convex curvature in the vertical plane. The mandibular dental arch curves toward the buccal side and the maxillary arch curves toward the tongue and the palate as viewed in the vertical plane.
The jaws are anisognathic. The mandibular dental arches are positioned slightly lingual to the maxillary dental arches. The buccal edges of the caudal mandibular molar cheek teeth, contact the palatal aspect of the opposing maxillary molar cheek teeth.
Dental attrition of rabbit cheek teeth
Dental attrition is critical to the oral health of rabbits since their teeth continuously grow. The buccal surfaces of the mandibular cheek teeth wear more quickly than the lingual aspects. The palatal-lingual aspect of the maxillary cheek teeth wear more than the buccal aspects of these teeth. The anisognathic relationships of the upper and lower jaws causes the occlusal wear patterns and the development of the occlusal plane.
The veterinarian must be aware that the maxillary cheek teeth are normally longer at the buccal aspect and shorter at the palatal-lingual aspect. The mandibular cheek teeth are normally shorter at the buccal aspect and longer at the lingual aspect. The maxillary and mandibular cheek teeth meet at approximately 15 degrees from horizontal (or level bite) to form the occlusal plane. The purpose of occlusal adjustment is to recreate this occlusal plane as accurately as possible. There is less attrition (wear) at the rostral and caudal aspects of the upper dental arches and more in the middle. The mandibular dental arches adapt to the maxillary dental attrition.
Cheek teeth shape
The occlusal cusp surfaces of the cheek teeth have enamel folds or ridges formed by enamel. The troughs consist of dentin and cementum.
The shape of the occlusal aspect of rabbit mandibular cheek teeth are very close to square. The buccal to lingual measurement is close to the mesial to distal measurement. The maxillary shape of the cheek teeth near the occlusal surface is somewhat rectangular. The buccal to palatal-lingual measurement is larger than the mesial to distal measurement.
lingual-palatal and buccal appearance
The side views of the mandibular cheek teeth have folds called embrasures. The buccal aspect of the mandibular cheek teeth have deep logitudinal embrasures and the lingual aspect has more shallow logitudinal embrasures. These embrasures are located near the distal third of the mandibular cheek teeth. The maxillary cheek teeth also have logitudinal embrasures; however, they run down the middle of the upper cheek teeth and are somewhat shallower than in the mandibular cheek teeth. In the upper dental arch, the first premolar tooth and the last molar tooth do not have embrasures. In the mandible the last molar lacks the embrasure but the first premolar has two embrasures on the buccal side and one on the lingual side.
Apical aspect of cheek teeth
The lower cheek teeth apices diverge and protrude toward the ventral-lingual aspect of the mandible. The upper cheek teeth converge and project toward the buccal aspect of the maxilla.