Page 6-continued

However another factor plays an important role in the production of acid, i. e., the amount of inoculum or number of bacteria with which the culture medium is inoculated. If, for instance, a tube of litmus milk is inoculated with say 2 or 3 cc. of rich culture, containing enormous numbers of viable bacteria, instead of the loopful as suggested above, containing relatively only a fraction as many, then we find acidity developing and the color changing within a shorter time, sometimes only a few hours.

Applying the above elementary information to our problem of preventing acid formation and thereby preventing caries, it is evident that removing from about a tooth all food material which may serve as culture media for acid producing bacteria and removing from the same location most of the bacteria, there will be little growth of bacteria (for lack of culture media) and no production of acid( for lack of fermentable carbohydrates) until food is again lodged at the particular place and sufficient time elapses for bacteria to multiply and produce acid.

Decomposing food material that has been retained and has accumulated about the teeth during the daytime gives the bacteria growing there a good start towards acid production by bedtime. If these conditions are allowed to continue through the night during sleep the most favorable conditions exist for more rapid bacterial growth and production of acids, and their action upon the teeth. As a matter of fact, the caries process progresses principally at night and during sleep. Therefore to prevent the initiation and further progress of caries the teeth must be effectively cleaned of food and accumulated bacterial material at night before retiring. Nothing else will suffice.

Early Stage Peridontoclasia

Periodontoclasia begins and progresses as a local microscopic disease process. The earliest stage lesions are too small and inaccessible to be recognized except by microscopic examination of suitable sections or other preparations of the tissues involved. What is ordinarily diagnosed clinically as periodontoclasia (pyorrhaea) on the basis of flow of visible amounts of pus, receded periodontal soft tissue, alveolar resorption, pocket formation, loosened drifting teeth, etc., represents, in fact, the far advanced stage and results of a disease that usually has existed and progressed at the particular location for many years. Long previously, there was an earlier stage, actually a beginning, of the same disease about the tame tooth. It is this earlier stage against which effective prevention must be directed. Measures for this purpose must be based upon clear understanding of the etiological conditions at the locations where the disease starts and from which the lesions about each tooth advance.

Relation Of The Enamel Cuticle To Early Stage Lesions

It has been shown that the enamel cuticle bears an important relationship to the early stage of the periodontoclasia lesion. The marginal gingiva normally rests upon the smooth, non-irritating enamel cuticle. Bacteria allowed to grow and accumulate for a long time on the tooth at the gingival margin, tend, in time, to produce microscopic roughness and hardened concretion upon the cuticle. The tendency is for this to increase, not only encroaching upon the gingival margin but extending into the gingival crevices (Figure 10). In time a narrow portion of the free gingiva (the free gingiva is that portion extending occlusalward from the level of the bottom of the crevice) rests against a surface covered with hard concretion and a pack of soft bacterial material. The irritation caused by the presence of this foreign

Continued...