116 SIXTH REPORT — 1836. 



rather than to the tension of the capsule, against which opinion the 

 immediate relief obtained by cutting the gum and capsule forms no 

 argument, as this operation would also have the effect of liberating 

 the pulp from pressure. When we contemplate the ultimate structure 

 of the nerves in the pulp, and consider that they are branches of so 

 complex a nerve as the fifth, we see sufficient cause for the numerous 

 morbid feelings and actions which may attend the development of 

 the teeth, and we may admit their connection with this event to the 

 extent supposed by Dr. Ashburner in his ingenious little work on 

 dentition. 



In the teeth we have an example of an animal substance resembling 

 the cartilaginous material of common bone, but placed out of the circu- 

 lation, and apparently carrying on no vital action, yet in immediate 

 contact with a pulp which is perhaps the most highly organized sub- 

 stance in the body, and adhering on the outside without a vascular 

 union to the periosteum which lines the alveola of the jaws, and the 

 vascular structure of the gums, and subject also to a peculiar species of 

 decay, which is neither like the mortification of li^^ng structure, nor 

 the putrefactive decomposition of the dead. The destruction of the 

 substance of the teeth by what is improperly called caries, takes place 

 in the following manner, wliich it is believed has not yet been accu- 

 rately described by any author. At first a dark green speck is observed 

 on the enamel. When a section is made of the tooth, the enamel at this 

 part appears to have lost its animal substance ; it is more porous, has a 

 more opake white colour, and appears as if it were charred by heat. To 

 this change succeeds the first step of decomposition in the proper sub- 

 stance of the tooth, which is marked by a greenish streak leading from 

 the place where the decay began in the enamel, to the nearest part of 

 the cavity holding the pulp. The enamel afterwards breaks down, and 

 is lost where it was first affected , and the fluids of the mouth are ad- 

 mitted more freely to the proper substance of the tooth, which becomes 

 soft, and gradually wears away, until the decay reaches the cavity of 

 the tooth. The pulp is then exposed, and usually inflames, causing one 

 species of toothache. Like all other very delicate tissues, such as the 

 brain and the nerves of vision and hearing, the pulp cannot bear ex- 

 posure and inflammation without sloughing more or less, and when 

 a part of it is thus lost, it is never repaired, nor properly speaking even 

 healed. The inflammation of the pulp may be excited, and kept up by 

 the shghtest external causes, such as contact of foreign bodies or any 

 unusual degrees of either heat or cold. The tooth-ache is frequently 

 produced by secret irritations of the sentient surface of the alimentary 

 canal, or of some other part of the nervous system, and hence it is 

 sometimes removed by an active purge, by baths, or by strong mental 

 impressions. 



That the decay of the substance of the teeth is not a vital action, as 

 supposed by Mr. Hunter and others, is proved by the fact of its taking 

 place even more readily in artificial teeth, than in those naturally fixed 

 in the head, whether these artificial teeth be taken from the human 

 subject or made of the teeth of an animal : and that it is produced by 



