26 
SUPERNUMERARY TEETH. 
(4) At a later stage wasting and loss of strength. In cattle epileptiform 
convulsions have been seen as a result of dental disease. In dogs 
salivation should always draw attention to the state of the mouth, and 
particularly of the teeth. 
Alveolar periostitis is the most common dental disease in animals, and 
always gives the mouth an extremely offensive smell. 
Immediately any such symptoms are present, the mouth, and especially 
the teeth, should be thoroughly examined. In some horses, irregularities 
of the teeth can he detected through the thickness of the cheeks by pal¬ 
pation from without. Sometimes the bone swells and fistulae form. The 
incisors are easily inspected, but examination of the molars requires certain 
precautions varying in the different classes of animals. Deviation of the 
teeth from their absolute or relative positions likewise points to disease. 
Diseases of the teeth may be clinically divided into the following four 
groups :— 
A. Irregularities in development. 
B. Irregularities in wear. 
C. Diseases of the tooth proper. 
D. Diseases of the alveolar periosteum. 
(A) IRREGULARITIES IN THE DEVELOPMENT OF THE 
TEETH. 
(a) EXTRA OR ADVENTITIOUS TEETH (POLYODONTIA, HYPERDENTITION). 
Kollmann states that in man during foetal life more enamel germ is 
sometimes formed than is required for the normal number of teeth, and 
that this determines the production of supernumerary teeth. Kitt looks 
on hyperdentition as a result of atavism, and points to the fact that in 
former ages foals had more teeth than at present. The same theory 
explains the appearance of the pre-molars in the horse, whose ancestors 
(Hipparion, &c.) always had four pre-molars. Kitt describes as a typical 
hyperdentition the apparently purposeless excess of teeth, an example of 
which is cited by Goubaux, where a certain horse had double the normal 
number of incisors. Gunther, Stockfleth, and others have noted super¬ 
numerary molars. Their commonest situation seems to be behind the 
third molar, but they may lie alongside the normal teeth, being either in 
contact with the tongue or cheek. At times milk teeth may be retained 
by becoming fixed between their permanent successors. 
Supernumerary teeth are seen in most of the domestic animals, super¬ 
numerary incisors, canines, and molars all being represented, the latter 
most frequently. A regular series of such observations in horses and 
oxen has been compiled by Morot, and in the dog by Sussdorf. 
Excess teeth seldom cause trouble until, by continued unopposed growth, 
