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caries as a whole. its clinical featuees. 107

Proximal Surface Decays in Incisors and Cuspids.
ILLUSTRATIONS: FIGURES 78-81, 129-133.
Principal clinical features: (1.) The V-shaped form of
the proximal surfaces. (2.) The necessity that cavities be
approached through the labial or lingual embrasures, differing
from the approach through the occlusal surface in the molars and
bicuspids. (3.) The curvature of the surface at the usual point
of initial attack carries extensions of decay along the dento-
enamel junction quickly to the undermining of the lingual or
labial enamel plates, or often both. (4.) The frequent danger
of the spread of decay incisally along the dento-enamel junc-
tion, destroying the support of the incisal angle. (5.) The ten-
dency to spreading of caries to the linguo-gingival and labio-
gingival angles of tbe surface, especially after fillings have been
made. (6.) The triangular forms of prepared cavities, with
extensions at the labio-gingival and linguo-gingival angles only,
instead of the square-cut cavities in proximal surfaces of the
bicuspids and molars. (7.) The necessity for forming incisal
anchorages of a form not used elsewhere. (8.) The greater
necessity for esthetic considerations in all parts of the treatment,
and especially in the preservation of the stronger parts of under-
mined labial enamel. (9.) The great danger of injury to the
attachment of the soft tissues to the tooth at the crest of the
arch of the gingival line on the mesial and distal surfaces in
the use of ligatures.
The two groups of Figures, 78-81, 129-133, taken together,
present a progression from the very early beginnings of caries
in the enamel in proximal surfaces of incisors and cuspids to a
very considerable invasion of the dentin. They give a fair view
of the usual conditions found, including the place of beginning
and the manner and direction of the invasion. Particular atten-
tion should be given to the arch of the gingival line as it passes
from labial to lingual across the proximal surfaces. This is
well shown in Figures 129, 130, which exhibit plainly the danger
of serious damage to the attachment of the soft tissue to the
tooth at the crest of the arch of the gingival line by tying liga-
tures tightly and forcing them to the gingival line on the labial
and lingual surfaces. This danger is found particularly with
the incisors and cuspids, and great damage is frequently done
by inattention to this point.