The author measured the length of teeth, ad roots at 30 men of the twenties who had a good occlusion and no restoration in the mouth using the intraoral x-ray film.
Also the author compared the ratio of anatomic crown and root length, and that of clinical crown and root length each tooth.
Results were as follows ;
1. The ratio of clinical crown to root length was that in the upper teeth, central incisor was 1. 22, lateral incisor 1. 45, canine 1. 65, first premolar 1. 57, and second premolar 1.74. And in the lower teeth, central incisor was 1. 27, lateral incisor 1. 31, canine 1.58, first premolar 1. 78, and second premolar 1.78.
2. The ratio of anatomic crown to root length was taat in the upper teeth, central incisor was 1. 19, lateral incisor 1. 34, and canine 1.60. And in the lower teeth, central incisor was 1.35, lateral incisor 1.38 and canine 1.56.
3. The ratio of clinical crown to root length in canines and premolars was better than 1 : 1.5.
4. Each tooth had the length of clinical root requiring in the construction of the simple crown
|