520 
MR. JOHN TOMES ON THE PRESENCE OF FIBRILS 
operation of removing the carious part is productive of pain, even from the com- 
mencement ; indeed pressure upon the surface of the softened tissue gives rise to dis- 
comfort, If in such cases the softened dentine be examined, fibrils may here and 
there be found but little altered from their natural appearance. 
The greater degree of sensitiveness observable in the dentine immediately below the 
enamel, that is, at the point of ultimate distribution of the dentinal tubes, and con- 
sequently of the fibrils, may be fully accounted for on the supposition that the latter 
are organs of sensation, just as in nerves of sensation the point of greatest sensibility 
is that of their ultimate distribution. 
The recognition of the dentinal fibrils must lead to a modification of the opinions 
hitherto entertained as regards the office of the tubes, namely, that they are for the 
circulation of fluids only. The presence of soft tissue would not, however, hinder 
the slow passage of fluids ; and that fluids do pass through or by the side of the fibrils 
is rendered probable by the fact, that they are capable of undergoing change at the 
parts furthest removed from the pulp. When the fibrils become calcified near the 
surface of the dentine, the hardening material must have been derived from the pulp 
when the consolidation has taken place in the crown of the tooth. 
The foregoing observations wiL I think warrant the conclusion, that the dentinal 
fibrils are subservient to sensation in the dentine, and are the channels by which 
nutrition is carried to that tissue. 
Further evidence may be adduced in favour of the latter opinion. I have already 
observed that dentine may remain for a time apparently unaltered if the pulp be 
destroyed and the cavity filled with gold. After a while many teeth so circumstanced 
become loose, and when removed it is found that a considerable portion of the den- 
tine has been removed by absorption ; a state of things in some respects similar to 
that which accompanies the loss of teeth in old people. Here we find, that, although 
the pulp may be living, the tubes of the root of the tooth have become eonsolidated, 
and the part rendered translucent. Teeth so circumstanced will on examination 
exhibit loss of dentine. A similar condition may be found in teeth the crowns of 
which have been lost; the roots are then diminished by absorption. In each of the 
instances adduced, the teeth may, however, be retained for a lengthened period in 
th e jaw, but such persistence is always accompanied by the deposition of cementurn 
to an unusual extent upon the roots. These phenomena have been brought forward 
to show, that the presence of the dentinal fibrils in a state of integrity is necessary 
to the normal condition of the tooth ; that if from any cause they are consolidated or 
destroyed, nature will coat over the root with cementurn, and often to an extent 
amounting to disease, or will set up a process for its removal. The dentine will 
be diminished by absorption, the root will be thrown up on the surface of the gum, 
or the socket will disappear, and the tooth by the one or other process, or by a 
combination of each, will be cast off as an organ no longer fitted for a place in the 
living body. 
