Page 230 - My FlipBook

114 PATHOLOGY OF THE HARD TISSUES OF THE TEETH.
enamel rods have begun to fall away at one point only. Figure
143 is a photograph of the buccal surface with the whitened
area also stretching from angle to angle, the shadow obscuring
a small part at the mesial angle. The distal surface, Figure
144, shows dark, but the decay is apparent, and on the buccal
surface, as seen in this photograph, the whitened line of carious
enamel is seen to advantage as it rounds to the occlusal follow-
ing the free margin of the gum to join the distal surface decay.
Finally, the whitened decay on the lingual surface, Figure 145,
is seen streaking away from the decay in the mesial surface
in a curved line, which is lost in shadow as it approaches the
distal angle, completing the circle of the tooth.
The pictures of this series are the final illustrations for the
explanation of the tendencies to spreading superficially on the
surface of the enamel and the direction of that spreading as one
of the principal clinical features of caries of the teeth, which
every dentist should fully understand and appreciate as his
guide in the preparation of cavities for the prevention of recur-
rence of decay about the margins of fillings. Every one should
understand distinctly that the spreading on the surface of the
enamel is a thing entirely different and apart from spreading
along the dento-enamel junction and destruction of the enamel
by backward decay, together with the general invasion of and
destruction of dentin by caries. This latter spreads in every
direction from the point of penetration of the enamel, having no
respect whatever for any particular surface or any of the angles
of the teeth. The spreading along the dento-enamel junction
this way or that has no clinical significance in connection with
the recurrence of caries about fillings. This invasion may pro-
duce broad cavities, cavities of awkward shapes, may weaken the
tooth by the destruction of dentin, and, in these and other ways,
has its special points of clinical importance. But this is all
secondary, occurring only after the enamel is broken. The clini-
cal importance of a full appreciation of the superficial spreading
of caries on the enamel has to do especially with the prognosis,
with the probable future of every case individually, and the
rational management of the teeth of each person under our care.
On the details of this management, the success or failure will
depend more than all else, supposing always that the details
of manipulation, as this may be planned, be skillfully executed.
Together with all of this, judgment must be stimulated and
quickened by a careful study of the conditions of immunity and
susceptibility to dental caries.