Collagen and Apatite in Hard Tissues and Pathological Formations 149 



Hansen, 1962; Hohling, 1963 a, b, 1964; Hohling and Pfefferkorn, 1964). Thus we 

 concluded that the macromolecular arrangement of collagen influences the length of 

 the apatite crystallites. 



Following the results of Hodge and Petruska (1963, Fig. 9) we assume that the 

 nuclei develop on certain "dark bands" of the collagen cross-striation within the so- 

 called "hole zone". In the area of the "hole zone" the nuclei grow in length (and also 

 in thickness), until they reach the "overlap zone" of the macroperiod in which there 

 seems to be a blocking force which prevents further growth in length (Hohling, 

 1964; Hohling et ai, in press, Fig. 5). 



In the case of dentine caries as an example of hard tissue decay we made the 

 following observations. In carious dentine it is mainly the thin, dark-looking apatitic 

 formations which are decomposed. But the light-looking crystallites are also affected 

 and disorganized in their arrangement. By the decomposition of the thin, dark- 

 looking apatitic formations the "cemented" collagen subfibers are set free but then 

 combine again to form thicker collagen fibers with the characteristic cross-striation 

 and macromolecular arrangement. (Of course this is not a new formation of collagen 

 fibers but only a lateral aggregation of subfibers to thicker fibers which already 

 existed before mineralization, in embryonic dentine.) These carious changes are shown 

 in Fig. 2. 



During further carious attack the macromolecular arrangement of collagen is 

 destroyed and the thicker collagen fibers are decomposed into their subelements. By 



■ £JA 



-V.SA- 



■// A ■ 



7./ A 



rr\ 



Fig. 3. Diagrammatical representation of x-ray wide angle — and low angle — patterns for sound and diseased 



tendon. The loss of reflexions from the sound to the diseased state (in the figure from left to right) is the 



same as from sound demineralized to carious additionally demineralized dentine. But for carious dentine there 



was seldom reached the stage i/, in which onlv the 4.5.4- and 11 A reflexion had remained 



combined x-ray diffraction and infrared-absorption analysis we found that the 

 collagen decay caused by dentine caries occurs in the same way as the collagen decay 

 described by us for human tendon and meniscus (Dahmen and Hohling, 1962; 

 Hohling and Dahmen, 1963; Hohling, 1963 c; Hohling et ai, 1965; Hohling 

 and Pfefferkorn, in press). 



