of the past fifteen years. Today we know that pyorrhea is a primary atrophy of the alveolar bone, the latter having a natural tendency to such atrophy because, unlike most bone, there are no muscles inserted in it. But occlusal impact takes the place of muscular attachment to some extent and there is normally an equilibrium between the occlusal impact and the tendency to absorption. Infection is only an unessential accident in the development of pyorrhea. In vertical pyorrhea we see separation of the teeth and loosening; followed by pocket formation and infection. In the horizontal type we see suppurative gingivitis and large quantities of supragingival calculus, pocket formation being slight and separation rare, loosening of the teeth occurring at a very late period. Diagnosis can be made only from roentgenograms which show the amount of absorption-never from mere presence of gingivitis or gingival suppuration. Horizontal pyorrhea can be prevented and benefited by ordinary buccal hygiene. In general the treatment should be prosthetic and surgical, local applications being of little value.
Atrophy
of the Alveolus
(Innsbruck).
Paradentitis
Vierteljahrsschrift
and Pyorrhea fiir
Alveolaris.
Zahnheilkundc.
F. J. Lang 1923, xxxix. 4.
The author cites the increasing consensus of opinion that pyorrhea is due to a primary atrophy of the alveolar process. In 1909 RGmer termed it a local osteomalacia, Hopewell-Smith and Talbot use the terms halisteresis and decalcification, and Fleischmann and Gottlieb osteolysis. Absorption of the calcium leaves the bone a mere mass of fibrous tissue. In order to throw some light on this subject the author examined the alveolar processes of 32 deceased subjects. There was apparently no selection of material but t.he cadavers were taken as they were sent into the section room. In six of the 32 there were present various degrees of pyorrhea; while the remaining 26, free from this affection, gave ample opportunity for controls, presenting a great variety of alterat,ions of non-pyorrheic character. The conclusions reached were as follows : alveolar atrophy is not a matter of years for while it is most often encountered in advanced age it may be met with in early life. It may be associated with a great variety of local and general conditions including cachexias; but in these cases there may not be the least suggestion of clinical pyorrhea. Alveolar atrophy may be favored by a great variety of local and general conditions-for example in the old by arteriosclerosis and independently of age by calculus formation. In regard to the exact cause of pyorrhea the author agrees with Rijmer and others that there is a form due to rarefying osteitis and paradentitis, which has a sequela, the atrophy of the alveolar process. Paradentitis is in other words something distinct from so-called primary or spont,aneous atrophy. The microscope is requisite to differentiate between these two conditions. The author does not deny that atrophy of the alveolar process may also be a factor in the development of pyorrhea, so that we have two forms of the latter, one secondary to atrophy from whatever cause while the other and more important is the result of inflammation of the paradentium and rarefying osteitis.