Biomedical subjects
Publications and source records attributed to S Edwardsson.
Forty-two adults, visiting a Swedish health home, participated in the investigation, which included a 6-day period of fasting, followed by a 6-day period with a lactovegetarian diet. The results obtained indicated only a minor and mostly not significant influence on secretion rate, buffer effect, concentration of various electrolytes, and number of lactobacilli and S. mutans of whole saliva.
Sorbitol is a commonly used sweetener in many so called sugar-free products, like chewing-gums, lozenges and medicines. It is also used as a stabilizer in tooth pastes and is found naturally in some fruits and berries. Many methods have been used to evaluate the cariogenicity of sorbitol, e.g. short and long term studies in man, animal experiments and pH-measurements in dental plaque in vivo and in vitro. Most of these studies indicate that sorbitol has a low or no cariogenicity. However, there are some data showing that frequent consumption of sorbitol may result in an increased acid production in dental plaque and in an increased number of sorbitol-fermenting microorganisms. This adaptation is probably of no or only minor clinical importance, at least for persons with a normal salivary function and for people with a moderate consumption of sorbitol-containing products. Thus, present knowledge shows that sorbitol might be considered as a "low cariogenic" sugar substitute.
The capacity of the oral bacteria Streptococcus mitior, S. mutans and S. sanguis to methylate mercury was investigated in vitro. Mercuric chloride and pulverized dental amalgam in distilled water, respectively, were used as sources of mercury. Methylmercury was found in the bacterial cells of all three tested strains. The results indicate that organic mercury compounds may be formed in the oral cavity.
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The efficacy of autoclaving high-speed dental handpieces was tested in two types of downward displacement steam sterilizers (instrument autoclaves), commonly used in the dentist's office. Eight series of experiments were performed with various sterilization schedules. Lubrication oils with or without antimicrobial agent were used in four of the series. Each handpiece was inoculated with 1 ml of a suspension containing equal amounts of saliva and spores of Bacillus stearothermophilus (approx. 10(6) spores/ml). Neither sterilization at 120-124 degrees C for 20 min nor at 134-136 degrees C for 10 min resulted in complete inactivation of the spores in series in which the instruments were tested without oil or with oil containing no antimicrobial agent. However, when the handpieces were lubricated with oil containing isopropanol and formaldehyde and the schedule 134-136 degrees C/10 min was used, no growth was observed. The results indicate that instrument autoclaves with built-in programs of 120-124 degrees C/20 min and 134-136 degrees C/10 min could have insufficient capacity to sterilize lubricated or unlubricated dental handpieces. The use of oils containing an antimicrobial agent can overcome this problem.
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The occurrence, viability and identification of the microbial flora under composite fillings using an anaerobic technique were studied. Class V cavities were prepared on clinically healthy buccal surfaces of 7 contralateral pairs of premolars in children 11--15 years of age. After preparation, rubber dam was applied and one cavity in each pair of teeth was washed with water blasted dry with air and filled with Adaptic. The other cavity was washed with a cavity cleaner (Tubulicid) and a cavity liner (Tubulitec) was applicated prior to filling with Adaptic. The teeth were extracted after 4--6 weeks. Under anerobic conditions the tooth crown was split. From one half samples were taken from the pulpal wall under the filling and cultured on blood agar and in broth medium. The other half was examined with histobacteriological technique. No growth occurred in cultures from lined cavities but in 6 of the 7 unlined cavities. Full agreement was observed between the findings from the culturing and histobacteriological examinations concerning presence or absence of microorganisms at the pulpal wall in all 14 teeth. The flora was mixed. Gram-positive bacteria, mainly Streptococcus and Actinomyces, dominated over gram-negative bacteria including Veillonella, Fusobacterium, Campylobacter and Selenomonas. The composition of the flora was more similar to that observed in dental plaque than that found in carious dentin or in saliva in other studies.
Lozenges containing hydrogenated starch hydrolysate (Lycasin), maltitol, sorbitol or xylitol were consumed 4 times daily during 3 months by 4 groups of persons (in all 85 subjects). In the maltitol-, sorbitol- and xylitol-group the plque wet weights were of the same magnitude before and after the test period. In the Lycasin-group, a higher value was found after than before the 3-month period (p less than 0.01). The acid production in suspensions of dental plaque material from Lycasin, maltitol and sorbitol expressed as per cent of that from glucose was approximately the same before and after the test period. From xylitol no acid production could be demonstrated either before or after the 3-month period. There were no statistically significant differences between the plaque pH-changes induced by rinsing with 50% solutions of Lycasin, maltitol, sorbitol or xylitol before and after the test period. However, there was a tendency (p less than 0.05) towards lower pH-values induced by the maltitrol and sorbitol rinse after the 3-month period compared with before. No difference in the relative numbers of facultative anaerobic streptococci. Streptococcus mutans or facultative anaerobic lactobacilli before and after the test period was found.
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