In filling the anterior teeth when the labial wall is gone, and the lingual wall intact or nearly so, use a piece of thin metal three-quarters of an inch long and wide enough to cover the cavity in the tooth to be filled, insert it between the teeth, and bend the lingual end over the cavity; the labial end is bent out of the way over the labial surface of the adjoining tooth, as shown in Fig. 4. When the labial wall is intact or nearly so, access to the cavity should be obtained from the lingual side, and in this case the bending of the shield would be reversed, as shown in Fig. 5. The shield is not absolutely essential, but it helps support the tin, and also keeps a separation. [Illustration: FIG. 4.] [Illustration: FIG. 5.] It is preferable to save the labial wall and line it with (say) five layers of No. 4 semi-cohesive gold folded into a mat and extended to the outer edge of the cavity; this gives the tooth a lighter shade, and bicuspids or molars can be filled in the same manner. Cases are on record where incisors with translucent labial walls, filled by this method, have lasted from twenty-three to thirty-seven years. CHAPTER VII. For the last ten years the writer has been using tin at the cervical margin of proximal cavities in bicuspids and molars, especially in deep cavities (now an accepted practice), and he finds that it prevents further caries oftener than any other metal or combination of metals he has ever seen used. In filling such cavities, adjust the rubber, and use a shield or matrix of such form as to just pass beyond the cervical margin; this will generally push the rubber out of the cavity, but if it does not, then form a wedge of wood and force between the metal and the adjoining tooth, thus bringing the metal against the cervical margin, and if a small film of rubber should still remain in the cavity, it may be forced out by using any flat burnisher which will reach it, or it can be dissolved out with a little chloroform. Fill from one-fourth to one-half of the cavity with tin, and complete the remainder with gold when the tooth is of good structure; this gives all the advantages of gold for an occlusal surface. Before beginning with the gold, have the tin solid and square across the cavity, and the rest of the cavity a good retaining form, the same as for gold filling; then begin with a strip of gold slightly annealed and mallet it into the tin, but do not place too great reliance upon the connection of the metals to keep the filling in place.