ABERRATIONS OP DENTITION. 117 



other, and the smaller dimensions of the fangs of the wisdom 

 teeth, owing to the contracted space in which they are 

 developed. These teeth decay early, are comparatively of 

 little utility, and probably from the same cause ; for in cases, 

 where prior to their development one of the molares in front 

 of them have been removed, they take a more forward 

 position, are developed with larger fangs, and become much 

 more serviceable. 



When the first teeth have made their appearance through 

 the gum, they are not yet completed ; the process of thickening 

 the body by~ layers from within, and of lengthening the root 

 below, is for a time still continued by the pulp. After their 

 completion, the only physiological changes they undergo, is 

 the wearing down of the bodies by friction, and the filling up 

 of the top of their cavity within by the pulp, with a yellowish 

 bony matter in old age, (cementum,) which prevents the 

 exposure of the cavity, and protects the vasculo-nervous pulp, 

 which is so exquisitely sensitive, as to be considered by some 

 in the light of a nervous ganglion. This latter process unhap- 

 pily is not universal, and is especially defective when the teeth 

 decay early in life, apparently before the period nature has 

 assigned them. 



* 



Aberrations of Dentition. 



Occasionally at birth teeth have been found developed on 

 the surface of the gum, as in the cases of Louis XIV. of France 

 and Richard III. of England : in such cases they are generally 

 mere shells, and are quickly shed, and below exist the double 

 series of germs, which are developed in the regular order. 

 In some rare cases, from the non-existence or disease of the 

 germs, no teeth have ever been developed.* Borelli mentions 

 a case of this sort occurring in a woman then seventy-two 

 years old. 



Sometimes the temporary teeth only exist, which fall at the 

 regular period and ?s never replaced. Occasionally the set 



* Oudet. Consid. sur la Nature des Dents et leur Alterations ; Journal Univ. 

 Des Sciences Med. torn. 43, 1826. 



