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130 PREPARATION OF CAVITIES
joining at definite angles, and give the box or mortise
form.
I. Pit and Fissure and "Gingival Third" Cavities.—With
the burs, excavators and chisels flatten the pulpal or axial wall
of the cavity, and true up the lateral walls until they are plane
surfaces, parallel with each other and joining with the pulpal
or axial wall (the seat) at definite angles (see Figs. 141, 142,
143 and 144).
Fig. 154. ^FiG. 155. Fig. 156.
Fig. 154.—Mesial cavity on an upper central incisor showing the flat gingival
wall.
Fig. 155.—Lingual view of the same cavity shown in Fig. 154.
Fig. 156.—Cavity shown in Figs. 154 and 155 seen from a different aspect. The
triangular form with three point angles is noticeable.
2. Cavities in the Proximal Surfaces of the Incisors and
Cuspids not Involving the Angle.— (a) With inverted cone burs,
hatchets, hoes and chisels, flatten the gingival and axial walls,
making a definite line angle at their junction, (b) Bring the
axial, gingival, labial and lingual walls together at two defi-
nite point angles (labio-gingivo-axial and lingo-gingivo-axial
(c) Join the labial and lingual walls together
point angles) .
at a definite point angle at the incisal portion of the cavity, the
resultant form being triangular in shape, with three definite
point angles (Figs. 154, 155 and 156).
joining at definite angles, and give the box or mortise
form.
I. Pit and Fissure and "Gingival Third" Cavities.—With
the burs, excavators and chisels flatten the pulpal or axial wall
of the cavity, and true up the lateral walls until they are plane
surfaces, parallel with each other and joining with the pulpal
or axial wall (the seat) at definite angles (see Figs. 141, 142,
143 and 144).
Fig. 154. ^FiG. 155. Fig. 156.
Fig. 154.—Mesial cavity on an upper central incisor showing the flat gingival
wall.
Fig. 155.—Lingual view of the same cavity shown in Fig. 154.
Fig. 156.—Cavity shown in Figs. 154 and 155 seen from a different aspect. The
triangular form with three point angles is noticeable.
2. Cavities in the Proximal Surfaces of the Incisors and
Cuspids not Involving the Angle.— (a) With inverted cone burs,
hatchets, hoes and chisels, flatten the gingival and axial walls,
making a definite line angle at their junction, (b) Bring the
axial, gingival, labial and lingual walls together at two defi-
nite point angles (labio-gingivo-axial and lingo-gingivo-axial
(c) Join the labial and lingual walls together
point angles) .
at a definite point angle at the incisal portion of the cavity, the
resultant form being triangular in shape, with three definite
point angles (Figs. 154, 155 and 156).
