380 



CHARLES E. STOCKARD AND A. L. JOHNSON 



dental malocclusion in the dog's skull is directly associated 

 with the increase in value for muzzle index. 



In text-figure 75, the palatal index for these skulls is shown 

 to be the most important fraction contained within the muzzle 

 index. The group with normal occlusion ranges in palatal 

 index from 80 to slightly below 60. The groups B, C and 

 D, with slight degrees of malocclusion, average much higher 

 for palatal index than do the skulls with normal occlusion, 

 while group E, with general malocclusion, shows a range 

 which lies entirely above the normal group. It is quite clear 

 that short, wide palates are strongly and directly associated 

 with dental malocclusion in the skull of the dog. 



A B C D E F G 



Text-figure 75. Relation of dental occlusion to palatal index in 184 skulls 

 divided into groups as indicated in text-figure 72. 



The indices discussed thus far have involved upper facial 

 dimensions with no consideration to the mandible or lower 

 jaw. An important factor in our study of dental occlusion 

 is to determine whether malocclusion is more largely due 

 to disproportions in the upper jaw or the lower jaw, and to 

 what degree each is responsible for such mechanical dis- 

 harmony. To determine these important facts, the mandibu- 

 lar index, the relation of intercondylar width to length of 

 mandible, has been charted in text-figure 76 for the seven 

 groups of skulls. With the exception of three of the forty-nine 

 normal specimens the range in value for this index lies 



