Page 52 - My FlipBook

20 DENTAL ANATOMY

12. Outline a figure (Fig. i8) consisting of three pyramids
and a trapezoid, placed base to base, and draw the buccal as- f
pect of showing three roots, buccal groove, curvature of the
6J
cervical line and location of the mesio- and disto-bucco-oc-

clusal angles.
13. The shape of the occlusal surfaces of _6^ 7^ _8_ is irregu- \
larly rhombic (Figs. 19, 20, 21). Draw three such figures and
outline the occlusal surface of 6^ 7^> _8_ one in each, showing
differences in general shape of the surfaces of the three, the

Fig. 22.—The molar triangle. Right upper first, second and third molars. A
Entrance to mesio-buccal canal; B, entrance to disto-buccal canal; C, entrance to
lingual canal.

difference in size of the disto-lingual lobe, location of the
fifth cusp on _^ and shape of the angles. Indicate by letters

the ridges, fossae, lobes and grooves.
14. The entrance to the canals on the floor of the pulp
chambers of upper molars is situated at the corners of an
imaginary triangle known as the Molar Triangle (Fig. 22).
Draw three triangles, one to represent each upper molar, right

side, showing the difference in the shape and size of the tri-
angles, due to diminution in the size of the teeth and change of
location of the disto-buccal canal. Indicate by letters on the
drawings the location of each individual canal.
15. Draw three cubical figures and place the mesial and

distal roots of a lower molar at their bases (Fig. 23). Indicate