Types of tooth

TYPES OF TOOTH
(OX, Sheep & Goat, Horse,Pig, Dog, Rabbit, Fowl )

Brachyodent tooth

  • They are simple, unspecialized tooth consists of conical crown, a slightly constricted neck and a simple conical root.

Hypsodent tooth

  • These are more specialized tooth where in crown and neck are not easily distinguished and there is only a body and root.

Isognathus and anisognathus

  • Isognathus animals with equal upper and lower jaw width whereas the lower jaw is narrower than the upper jaw is called as

Ox

  • The incisors are absent in the upper jaw. There are 8 incisors in the lower jaw arranged in a fan-like manner
  • They are all simple teeth and have no infundibula. The crown is white, sharp and shovel-shaped. Each presents labial and lingual surfaces separated by a sharp edge in front
  • The crown is at first entirely covered with enamel but later as the masticatory surface is developed the dentine comes into view on the surface
  • The root is rounded and is embedded in the jaw as to allow a small amount of movement. Neck is very distinct
  • The incisors are termed as centrals, intermediates, laterals and corners of which the corners are probably canines
  • The incisors do not undergo continued eruption but the length of the crown is maintained by retraction of the gums
  • The deciduous incisors are smaller and the crown is narrower and the canines are absent.
  • The cheek teeth are made up of three premolars and three molars in each side of upper and lower jaws
  • They are small but they show gradual increase in size from first to the last. The enamel folds on the tables are prominent
  • The tables are not flat but oblique. The upper teeth are longer on the outside and the lower ones on the inside 

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Sheep and Goat

  • Same as ox.
  • The incisor teeth form a narrow and strongly curved arch
  • The crown is long and narrow
  • Their labial surfaces are strongly convex and end at a sharp edge, which is used, in chopping the grass
  • The roots are more firmly embedded than ox
  • The cheek teeth resemble ox but have a thinner layer of cement, which is often blackened by deposits from the food

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Horse

  • The formula for the permanent teeth of horse is, 2 (I.3/3 C.I/I P.M. 3 or 4/3, M 3/3)=40 or 42.
  • Incisors: They are twelve in number, six in each jaw placed close together so that their lateral edges form almost a semi circle in the young horse. These teeth have the peculiarity of presenting instead of the simple cap of enamel on the crown, a deep invagination -the infundibulum that becomes filled up with cement. Hence as the tooth wears the table has a central ring of enamel surrounding the infundibulum in addition the peripheral enamel. The cavity becomes darkened and is termed the cup or infundibulum mark.
  • Each tooth is so curved as to present a convex lateral surface and the embedded part of the teeth converge. The tooth tapers from the crown to the root regularly so that there is no distinct neck. In young horse, the masticatory surface is broad transversely towards the middle of the tooth, the two diameters are about equal and near the apex, and the antero-caudal diameter is considerably greater than the transverse diameter.
  • This fact is of value in the determination of age since the masticatory surface at different ages represent a series of cross sections. As the crown wear down, the embedded part emerges from the alveolus so that the tables of the first and second incisors are at first oval, with the long diameter transverse; at old age the tables are triangular, the base being at the labial edge. At the same time, the infundibula become smaller with age, approach the lingual border and finally disappear. Another important feature is one of the progressive approaches to the horizontal direction of the teeth as age advances. They become parallel and even convergent.
  • Canines: They are four in number in the male and rudimentary or absent in the mare. The upper canines are at junction of the premaxilla, the lower ones being nearer to the comer incisors. They are slightly curved with concavity directed inwards. The embedded part is round and the pulp cavity is large.
  • Cheek teeth: They are twenty-four, twelve in each jaw. Sometimes there is a first premolar in the upper jaw - wolf tooth and rarely a corresponding one in the lower jaw.
  • The cheek teeth are large, prismatic in form and quadrilateral in section except the first and last, which are three sided. The crown is long and most of it is embedded and erupts as the part wears away.
  • The upper cheek teeth are embedded in the alveolar processes of the maxilla
  • They are slightly curved with the convexity towards the cheek. The embedded parts diverge. The buccal surface presents a central ridge and two grooves
  • The lingual surface presents wide rounded ridge separating two grooves
  • The masticatory face presents two infundibula. It slopes downwards and outwards so that the buccal edge is prominent and sharp
  • The first and last have three roots and others three or four. The roots of the last three and sometimes that of the third also project into the maxillary sinus.
  • The lower cheek teeth are implanted in the rami of the mandible, forming two straight rows
  • The buccal surface has a longitudinal furrow
  • The lingual face is uneven having 3 or more grooves
  • The masticatory surface is oblique, slopes upwards and inwards so that the lingual edge is prominent. The first five have two roots, and the sixth has three
  • Two infundibula run through the entire length of the crown
  • The temporary teeth are smaller, present a distinct neck, crown is very short, infundibula are shallow. The canines do not erup

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Pig

  • The dental formula is 2(I. 3/3 C. 1/1 P.M. 4/4 M. 3/3)=42
  • The upper incisors are small and separated by each other by spaces and from the canines by a large interval
  • The first incisors are the largest
  • The lower incisors are horizontal and convergent and close together
  • The canines or tusks of the male are greatly developed and project out of the teeth
  • The upper one is 3-4 inches whereas the lower one is 8 inches
  • The cheek teeth increase in size from before backward

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Dog

  • The dental formula is 2 (I. 3/3 C. 1/1 P.M. 4/4 M. 2/3) = 42
  • The incisors are placed vertically and close together
  • They do not correspond to an opposing tooth but to parts of two teeth of the opposite jaw like the dovetail
  • The canines are large, conical and curved. The upper canine is separated from the comer incisor by an interval into which the lower canine is received
  • The lower canine is close to the comer incisor
  • The cheek teeth are 6/7 and the masticatory surfaces are tuberculate, having conical projections
  • The fourth of the upper row and fifth of lower row are much larger than the rest and are termed carnassial or sectorial teeth

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Rabbit

  • The dental formula is 2(I 2/1 C 0/0 P 3/2 M 3/3)
  • Each half of the upper jaw has two sharp chisel incisors
  • The larger one is situated in front and the smaller one is placed behind, as if to support the larger one 

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Fowl
Last modified: Friday, 20 April 2012, 8:57 AM