Dental plaque is generally considered to be of paramount significance in the etiology of dental caries and periodontal disease. Its microbial content, biochemical composition and its mode of formation may be great important to control of dental disease.
Since Miller(1890) had proposed that bacteria which producing sufficient acid to decalcify the tooth were etiologic agents of dental caries, almost all investigators aimed at the control of caries was directed towards increasing the resistance of the tooth to acid dissolution. Stephan(1953) has reviewed the historical development of the plaque concept. In the intervening years, a number of investigators attempted to equate the specific microorganisms with plaque formation and dental caries because of their ability to produce mucinous polysaccharides from sucrose.
A nummerous researchers have been participated to seek for the nature and role of dental plaques by bacteriological, biochemical and pathological methods or electron microscopic examination and fluorescent antibody techniques. Its microbial content, mode of formation and relationship to dental caries and periodontal disease, have been discussed in several recent reviews(Mandel, 1966; Leach, 1970; Dawes, 1968; Jenkins 1968, 1972; Keyes, 1968; Meckel, 1968; Schroeder, 1969, Egelberg, 1970; Kleinberg, 1970; Socransky, 1970; Gibbons and van Houte, 1973).
And, there are two intraoral processes, those are, microbial colonization and mineralization processes. It iss ure that plaque are concerned in periodontal inflammation by endotoxins, enzymes, and antigens; in caries by acid production: and in calculus formation with mineralization.
This study was dealt with oral flora and inorganic constituents of dental plaque of 279 Korean women:
1) Oral examination by the recommanded criteria of W.H.O.
2) Dental plaqnes of low right canine and first molor of each subject were collected and were cultured on the plate, of blood agar, nutrien agar, eosin methylene blue(E.M.B.) agar, sabouraud's media and bromcresol purple(B.C.P.) media in an aerobic condition. The specimen was also cultured anaerobically in thioglycollate broth medium and on blood agar plate in Torbal jar. On the other hand, direct smear were obtained and stained by gram and acid-fast staining.
3) On blood agar those were cultured anaerobically and aerobically, colony countings were done for the total viable count.
4) Attaching the alminium foils on the lingual surfaces of ower central incisors for 1, 2, 3, 5, 10 and 15-days, measured their weight. Then, dried for three hours in 110℃. for the measurement of Ca, Mg, K, and Zn, the quantity was analysed by the atomic absoption spectrometry, Model 303 of Perkin-elmer Co.. And the
measurement of phosphorus was done by Fiske-Subba-row method.
5) For the electron microscopic study, the following processes had done: fixation of plaque at 4℃ with 3% glutaraldehyde and osmium tetroxide solution; dehydration with alcohol and propylene oxide; embedding(Epon 812); ultrathin section of 500∼600A; staining of uranyl acetate and lead citrate; and observation with
electron microscope(Hitachi, HU-11, E-1 type).
The results obtained in this study were as follows:
1.l Prevalence of dental caries of the subject was 91.9%, while the control group reveals 83.3%.
2. In identification of microflora isolated from dental plaque(N=279), 127 cases(45.1%) were identified. Bacterioides sp.(9.8%), Straphylococcus(9.1%), Streptococcus(7.1%) are found as predominant species; and the unidentified 170 cases could be classify into species only morphologically. Among them the gram
negative bacillus, long and thin from were in 52 cases(17.5%), short and coccoid from in 47 cases(15.8%); and unidentified of gram positive bacilli in 25 cases(8.4%).
3. The total viable count of the anaerobic and aerobic culture reveals increasing with the age of deposit day by the eleventh day except the fifty day. The count of the eleventh day was 27.0×10**7 cell/ml and 12.5×10**7 cell/ml of aerobic
cultivation. After the fifteenth day it decreased to 1.4×10**7 cell/ml and 1.5×10**7 cell/ml respectively.
4. The analysis of inorganic constituents of dental plaque which were obtained from alminium foils showed increasing tendency with the age of deposit day, especially by fifth day. Calcium, magnessium, potasium, zinc, and phosphorus are increased. Ca/P ratios of 1, 2, 3, 5, 10, and 15 day were 1.00, 1.11, 1.80, 1.80, 1.70, and 1.67.
5. Of electron microscopic finding, nummerous microorganisms were found in early stage. However, after two weeks, especially after five weeks, crystal-like substance, those are, needle-shaped crystal and platelet-sharped crystal revealed obviously as other investigators reported.