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OUTLINE FORM 35

at right angles to the seat of the cavity, and pass under the free
margin of the gum at a point in full view of the operator.
Rule 9. Enamel Margins. The enamel margins should be planed
smooth to a full cleavage of the enamel rods and then slightly
beveled that the rods at the cavo-surface angle may be full-length

Fig. 13.—Technic group illustrating outline form.

Fig. 14.— Another view of cavities illustrated in Fig. 13.
rods, supported by shortened enamel rods which are protected by
the overlying filling material.
Rule 10. Extension for Prevention. When possible, carry the
cavity outline upon smooth, unclean surfaces, from an area of great
liability to caries to an area of lesser liability to caries.
This has reference to caries of enamel only and will come into