90 Philippine Journal of Science 1920 
sometimes, the whole group of symptoms in certain isolated 
clinical cases. The reason why due consideration has not been 
given dental infections is that we have been treating morbid 
conditions; symptoms and their clinical course we never thought 
might have an intimate relation with dental lesions. 
The researches of E. C. Rosenow and of Frank Billings, con- 
firmed later by Hartzell and- by others, as to the relation of 
various pathological manifestations to chronic dental infections, 
have been the guide of radiologists, dentists, physicians, and 
laboratory workers. In consequence the medical literature has 
been enriched by enough data to enable us to form a clear and 
exact idea concerning the intimate relation existing between 
chronic dental infections and certain forms of arthritis, neuritis, 
neuralgia, various types of rheumatic manifestations, and certain 
pathological conditions in the stomach, the duodenum, the ap- 
pendix, the gall bladder, the heart, and the kidney, and blood 
diseases such as pernicious anzmia, etc. 
Taking into consideration the fact that the manifestation of 
chronic dental infection cannot generally be diagnosed with ac- 
curacy by any clinical means without the X-rays—and even with 
them in certain cases with difficulty—I will first deal with the two 
main dental infections that commonly bear relation to the morbid 
manifestations mentioned; namely, the apical and periapical 
abscess and pyorrhea alveolaris. As a routine in our dental 
radiograms we employ the extraoral method with photographic 
plates and, exceptionally, the intraoral by means of photographic 
films and plates of proper dimensions to be placed within the 
mouth. We deem the extraoral method more practical, in a5 
much as it enables us to obtain, not only a large number of teeth, 
but certain information concerning both maxille, especially the 
upper, in its relation with the nasal cavities and the maxillar 
sinuses. : 
With a well-conducted technic, we are able to make a complete 
exploration of both maxille, and their respective teeth, by five 
exposures, whereas twelve at least are necessary in the intrao 
method—six exposures for the inferior—provided that every one 
of the exposures is satisfactory. 
In order to save time on one hand, and to avoid the patient 
being unduly exposed to the X-ray on the other, we decided to 
use the extraoral in preference to the intraoral. 
We use the oblique projection technic recommended by Drs- 
E. Speder, J. Belet, and J. D. McCoy. 
