Of course, the shape and placing of the teeth are not without significance in the character given by the mouth. When the upper gum shows above the teeth directly the lips are open, it is a sign of a selfish and phlegmatic nature.
Short, small teeth are held by the old physiognomists to denote weakness and short life, whilst rather long teeth, if evenly set in the head, denote long life.
The more the teeth, in point of size, shape and arrangement, approach to those of the carnivorous animals, the more violent are the animal instincts in the person; whilst the more the human teeth in shape and position approach to those of the graminivorous animals, the more placid is the character.
White, medium-sized and evenly-set teeth, which are seen as soon as the mouth is open, but which are never exposed—that is, which do not at any time show the gums—are a sign of good and honest natures.
Projecting teeth show rapacity; small, retreating teeth, such as are rarely seen unless in laughter, show weakness and want of physical and moral courage. The lower teeth projecting and closing over the upper range are indicative of a harsh nature.
In most faces the mouth or the nose is the more prominent. Where the nose is the dominant feature, energy, command and force of willpower, combined (unless the mouth and eyes show great kindness) with selfishness, show themselves in the character. Where the mouth, jaw and chin are more prominent, the appetites and passions are strong.
Broad jaws, with a broad forehead, mean both force of intellect and force of animal passion. Byron had this combination of brow and jaw; but the lips, which were full and flexible and with upward-curving corners, redeemed the sensuality given by the jaws, and the intellectual qualities shown by the form of the brow were in excess of the indications of voluptuousness given by the lower part of the face.
A person who has the jaw much broader than the brow and head has strong passions and a weak intellect—the very worst possible combination.
When the jaws are massive and yet the head and brow are more so, we have a powerful character, who can exert all his intellectual powers on one subject—one who has the very valuable faculty of concentration.
Where the jaws are much narrower than the head, we have a character where the sensual instincts are feeble, and where intellect is of a subtle and refined order. Wit is shown by this form of face, especially if the nose is delicately outlined, the tip pointed and somewhat drooping over the mouth.