314 



I. REICIIBORN-KJENNERUD 



Fig. 12. Detail of Fig. 11. A vessel from the gingiva is entering the resorp- 

 tion cavitv, which is filled with connective tissue and bonelike structures. 



(X35.) 



bone from the pericemental side of the lamina dura mav be found 

 while no resorptions or very small ones are seen on the opposing 

 tooth surface. 



It has not been explained why the alveolar bone often is resorbed 

 before the teeth, as is also the case in orthodontic treatment. Ac- 

 cording to histological observations, resorptions do not appear on 

 a root surface where pericemental fibers are intact. This indicates 

 that the fillers must be broken down before the resorption can take 

 place. On the pericemental side of the lamina dura there usually are 

 some places not covered by pericemental fibers, particularlv near 

 the canals where branches of the interalveolar vessels enter the 

 pericementum. This may be the reason why alveolar bone is re- 

 sorbed before the teeth. 



In most of the resorption cavities it can be seen that resorption 

 has been followed by apposition of a bonelike hard tissue, which 

 again may be broken down. This is probably due to changes in the 

 tissue tonus in the resorbing connective tissue. 



