– The objective was to compare the erosive effect of some commonly used acidic drinks and milk products on a bovine tooth enamel model system. Conditions were selected to be sufficiently severe to cause erosion. Loss of material after erosion experiments was measured by recording the depth of the surface profile after repeated and prolonged exposure. Changes in the enamel surface were observed by scanning electron microscopy. The reparative mechanisms were studied by immersing test teeth in saliva, with or without (2 ppm) fluoride, after severe demineralization in the test products. According to the t‐test for paired means, cola beverages and orange beverages differed from beer, coffee with or without sugar, strawberry yoghurt, buttermilk, and carbonated mineral water at the level P0.01. Each of the last‐mentioned test products differed from sports drinks, diet cola beverages and orange juice less significantly. In addition, bathing of teeth in saliva between exposures to the test products did not influence the erosive depth. The results, based on in vitro conditions that ensured erosion, are useful for comparative purposes but cannot be directly extended to the oral cavity under normal use conditions.

Dental erosion is often seen on the lingual tooth surfaces. For this reason tongue pH after consuming orange juice, Coca-Cola (old and new formula), Coca-Cola Light, Jaffa orange beverage, Hart-Sport sport drink, coffee (with and without sugar), beer, sour milk, and strawberry yoghurt was studied in a test panel. The lowest pH values which also remained low for the longest time were observed after consuming Hart-Sport (pH down to 3.80), orange juice, yoghurt, Coca-Cola, and Jaffa, in comparison with coffee (pH down to 5.26), Coca-Cola Light, and beer (p < 0.001). The total glucose concentration in the products and in saliva after consuming them was measured in order to assess the clearance of the products from the mouth. Hart-Sport yielded the highest salivary glucose concentrations (14,000 ppm total glucose) immediately after consuming while yoghurt (4,520 ppm) and coffee with sugar (6,480 ppm) caused the least elevation (p < 0.05). All study products, however, were quickly cleared from the mouth and practically no glucose was left in saliva 30 min after ingestion. Since all the studied products caused lowering of tongue pH below pH 5.5, they have the potential to cause adverse effects on the teeth in patients with impaired salivary function. In the healthy subjects in this study, however, the buffering capacity in the mouth was so strong that not even tongue mucosa could be shown to keep low pH levels a couple of minutes after consumption.

Subepithelial basement membrane (BM) of gingiva serves as an important barrier for bacterial penetration. Degradation of Type IV collagen, a major component of BM, was studied by incubating different Type IV collagen preparations with extracts of cultured oral microorganisms at neutral pH. Of the tested species Bacteroides gingivalis and Treponema denticola showed the strongest capacity to degrade Type IV collagen. Both soluble and insoluble substrates were extensively degraded. Limited cleavage of soluble Type IV collagen was observed by Bacteroides asaccharolyticus, Bacteroides endondontalis and Capnocytophaga ochracea. Negligible activity was found with Bacteroides intermedius, Actinobacillus actinomycetemcomitans and Fusobacterium nucleatum. The general proteolytic activity as assayed by the degradation of fibronectin, elastin, casein and some synthetic aminoacid substrates followed the same trend. B. gingivalis and T. denticola showed the highest proteolytic activity. The others tested showed variable and usually less activity towards the various substrates. According to the results B. gingivalis and T. denticola possess a strong proteolytic arsenal, a characteristic probably related to their virulence.

Variations in the outer membrane proteins (OMPs) and lipopolysaccharides (LPSs) of 54 isolates belonging to 16 different pathovars ofXanthomonas campestris were characterized. OMP samples prepared by sarcosyl extraction of cell walls and LPS samples prepared by proteinase K treatment of sonicated cells were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence of 4 M urea. In general, the OMP and LPS profiles within each pathovar were very similar but different from the profiles of other pathovars. Heterogeneity in OMP and LPS profiles was observed within X. campestris pv. campestris, X. campestris pv. translucens, and X. campestris pv. vesicatoria. LPSs were isolated from six X. campestris pathovars, which fell into two major groups on the basis of 0 antigenicity. The 0 antigens of X. campestris pv. begoniae, X. campestris pv. graminis, and X. campestris pv. translucens cross-reacted with each other; the other group consisted of X. campestris pv. campestris, X. campestris pv. pelargonii, and X. campestris pv. vesicatoria. A chemical analysis revealed a significant difference between the compositions of the neutral sugars of the LPSs of those two groups; the LPSs of the first group contained xylose and a 6-deoxy-3-0-methyl hexose, whereas the LPSs of the other group lacked both sugars.