306 



I. REICIIBORN-KJENNERl I) 



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Fig. 5. Reduction in the lumen ot an artery, from a biopsy of a patient with 

 anemic gingiva. In the wall of the vessel, which is verv thick, atrophic and 

 degenerative changes can be seen. ( X 200.) 



The Effect of Increased Functional Stress 

 ON THE Alveolar Bone 



It has been explained that the masticatorv functional stress in- 

 creases when alveolar bone is resorbed and that this may incite a 

 compensatory bone formation. A corresponding production of ce- 

 mentum and pericemental fibers also takes place ( Reichborn-Kjen- 

 nerud, 1956). 



Mechanical functional stress does not have a formative effect, but 

 a destructive one if it is raised above a certain limit. This has been 

 proved in the previously mentioned experiments bv Haupl and 

 Psansky ( 1938 ) , who by means of activators increased the magni- 

 tude and frequency of the intermittent masticatory impulses. When 

 the appliance had been in the mouth for 3 nights, compensatory 

 tissue production was dominant; onlv in some areas were circulatory 

 disturbances and bone resorption observed (Fig. 6). In sections 

 from patients who had used the activators for 7 nights, extensive 



