Effect of water-soluble reduced chitosan on Streptococcus mutans, plaque regrowth and biofilm vitality

The purpose of the present study was to examine the effects of a newly developed water-soluble reduced chitosan on Streptococcus mutans, plaque regrowth, and biofilm vitality. A 1.0%, water-soluble reduced chitosan, with pH ranging from 6.0 to 6.5, molecular weights between 3,000 and 5,000 Da, and 70% degree of deacetylation, was used. To determine antibacterial and antiplaque potency of chitosan, minimal inhibitory concentrations (MICs) for S. mutans and S. sanguinis (formerly S. sanguis), short-term exposure to S. mutans, and clinical trial of plaque regrowth and biofilm vitality were conducted. Twelve dental students volunteered to participate in the 6-week, double blind, randomized clinical trial using the classical 4-day plaque regrowth design. The MIC of water-soluble reduced chitosan for S. mutans was 1.25 g/l. While the cells exposed to distilled water (DW) grew rapidly, with a maximum turbidity reached by 16 h postinoculation, S. mutans exposed to chitosan (5.0 g/l) exhibited a substantial delay in growth and reached a maximum turbidity by 32 h postinoculation. The chitosan solution reduced the plaque index and the vitality of the plaque flora significantly when compared to DW, but this was less than the reductions found with the positive control of 0.1% chlorhexidine solution. The water-soluble reduced chitosan exhibited potent antibacterial effect on S. mutans, and displayed a significant antibacterial and plaque-reducing action during the 4-day plaque regrowth.

A comparison of oral health related quality of life between complete and partial removable denture-wearing older adults in Korea

The purpose of this study was to compare the oral health related quality of life (OHRQoL) between older Korean adults with complete and partial removable dentures using oral health impact profile (OHIP). A pool of 4250 Korean older adults was identified by random stratification by area from the sample cohort of Korean National Survey of Oral Health in the year of 2000. Out of the potential pool, 445 subjects with removable partial dentures (RPDs) or complete dentures (CDs) agreed to be interviewed by telephone. Each question in the survey was about how frequently each event was experienced during the past 12 months. To analyse the association between OHIP scores and removable denture status, bivariable analysis and multiple linear regression analysis were used. RPD users showed higher scores on eight items than CD users. They were 'breath stale', 'food catching', 'sensitive teeth', 'toothache', 'tense', 'unable to brush teeth', 'less tolerant to family members' and 'irritable with others'. RPD users might be associated with higher scores of functional limitation, physical pain and psychological discomfort than CD users. RPD users had slight tendency to be associated with higher OHIP-49 score than CD users, but it was not statistically significant. The findings of the present study confirm that there is no general OHRQoL difference between RPD and CD users. But in the items and subscales of OHIP, RPD users might experience more impaired OHRQoL than CD users.

Herpes simplex virus enhances the 7,12-dimethylbenz[a]anthracene (DMBA)-induced carcinogenesis and amplification and overexpression of c-erb-B-1 proto-oncogene in hamster buccal pouch epithelium

We studied the effects of herpes simplex virus type 1 (HSV-1) inoculation and topical 7,12-dimethylbenz[a]anthracene (DMBA) application, alone or in combination, on the carcinogenesis and on the amplification and expression of various cellular proto-oncogenes in hamster buccal pouch tissue. Topical DMBA treatment produced tumor formation in pouches, but HSV-1 inoculation, alone caused no neoplastic changes. In pouch tissues receiving both DMBA application and HSV-1 inoculation, the development of initial leukoplakia and tumor has hastened and enhanced in comparison with those receiving DMBA alone. Topical DMBA application to pouch tissue induced an amplification and an increase in the expression of cellular erb-B-1 (c-erb-B-1) proto-oncogene in the epithelial tissue, whereas repeated infection with HSV-1 alone did not. Topical DMBA combined with HSV-1 inoculation, however, resulted in greater amplification and expression of c-erb-B-1 proto-oncogene in the pouch epithelial tissue compared to the DMBA alone. These data indicate that HSV-1 inoculation significantly increases the carcinogenic activity of DMBA, in part, by probably enhancing DMBA-induced amplification and expression of c-erb-B-1 proto-oncogene in hamster buccal pouch tissue.

Knowledge of and practices related to caries prevention among Koreans

OBJECTIVES

This study assessed the knowledge and opinions of caries prevention and source of oral health information among Koreans.

METHODS

A questionnaire consisting of 36 items was used to interview 2,000 Koreans 10 through 69 years of age. Results for only selected questions are reported. A multistage, stratified, random sampling method was used.

RESULTS

Sixty-nine percent of the respondents had heard about fluoride. Only 16 percent knew that some community water supplies in Korea are fluoridated. Fifty-five percent of respondents who knew about community water fluoridation learned the information from television, whereas 28 percent read about it in a newspaper. Among those respondents who reported hearing about community water fluoridation, only 30 percent had precise information about its purpose. Fifty-five percent of the respondents reported that toothbrushing is the best way to maintain good oral health. Almost all respondents (97 percent) reported brushing their teeth one or more times a day.

CONCLUSIONS

These data indicate that there is a relatively low level of accurate knowledge about dental caries prevention among Koreans 10 through 69 years of age. The majority of respondents report learning information about oral health from the mass media.

National survey of Korean dentists' knowledge and opinions: dental caries etiology and prevention

OBJECTIVE

Dentists have the potential to influence what their patients know and do regarding dental caries prevention. The practices of dentists and what they tell their patients are influenced, in part, by their own knowledge and opinions. The purposes of this study were to determine the level of knowledge and opinions about caries etiology and prevention among Korean dentists and to describe related factors.

METHODS

A pretested, 27-item questionnaire was mailed to 2,047 dentists, selected by a stratified random sampling allocated proportionately. A postcard reminder was sent to all dentists after one week. Nonrespondents were sent additional complete mailings after three, seven, and nine weeks. The response rate was 83 percent (n = 1,700 dentists).

RESULTS

Analysis of six factors thought to be related to knowledge about caries etiology and prevention showed that recent graduates and dentists who worked in public health centers were likely to be more knowledgeable about caries etiology and prevention than their counterparts (P < .05). In regression analysis of perceived effectiveness of caries-preventive procedures for children, recent graduates, males, and dentists who worked in public health centers tended to rate caries-preventive procedures more effective than other dentists (P < .05). Dentists who had experience with school-based preventive programs and dentists in rural areas were likely to rate caries-preventive procedures for adults more effective than other dentists (P < .05).

CONCLUSIONS

Overall, results of this study suggest that the majority of dentists do not know current information concerning etiology and prevention of dental caries, mechanisms of action of fluoride, and effectiveness of preventive procedures for children and adults. Efforts to enhance the level of knowledge and practices of Korean dentists about caries prevention should focus on strategies to educate older graduates and female dentists, especially those in private practice.

Korean dental hygienists' knowledge and opinions about etiology and prevention of dental caries

OBJECTIVES

Because of their formal education Korean dental hygienists have the potential to be the primary source of information on caries prevention for patients and the general public, and influence the use and adoption of caries preventive procedures. The purposes of this study were to determine the knowledge and opinions about caries etiology and prevention among Korean dental hygienists, and to describe associated factors.

METHODS

A pre-tested, 20-item questionnaire was mailed to 1120 dental hygienists selected by stratified random sampling and allocated proportionately. A postcard reminder was sent to all dental hygienists after 1 week. Non-respondents were sent additional complete mailings after 3 and 7 weeks. The response rate was 77% (n=863).

RESULTS

Analysis of six factors thought to be related to knowledge about caries etiology and prevention showed that dental hygienists who were taught to provide oral health education and believe that it is desirable to practice oral health education during dental hygiene school and those employed in health centers were likely to be more knowledgeable about caries etiology and prevention than other hygienists (P<0.05). In regression analysis of the perceived effectiveness of caries preventive procedures, hygienists who provided oral health education during their formal training tended to rate caries preventive procedures as being more effective than other dental hygienists (P<0.05).

CONCLUSIONS

Overall, the results of this study suggest that most dental hygienists do not have up-to-date information on the etiology and prevention of dental caries, mechanisms of action of fluoride and effectiveness of preventive procedures. Efforts to increase the level of knowledge of Korean dental hygienists about caries prevention should focus on strategies to educate dental hygienists who have not been taught to provide oral health education, who do not have favorable opinions about the desirability of oral health education, and who had no experience with providing oral health education as part of their work, especially hygienists working in private clinics. Further, these efforts should include the revision of dental hygiene curricula and continuing education courses.

Effect of smoked tobacco tar on the growth, cytolytic action, DNA synthesis, and gene expression of herpes simplex virus

Previous experiments have shown that topical application of smoked tobacco tar condensate to HSV-infected oral mucosae of mice promotes neoplastic changes. Although HSV is an oncogenic virus, the virus must be inactivated and lose its cytolytic activity to be oncogenic in vitro and in vivo. Therefore, we investigated the effect of the water-extractable components of smoked tobacco tar condensate (smoked tobacco tar extract) on the growth, cytolytic activity, DNA synthesis, and gene expression of type 1 herpes simplex virus (HSV-1). Diluted tar extracts in tissue culture medium markedly inhibited the replication and cytolytic activity of HSV-1 in vitro. The smoked tobacco tar extract also notably inhibited the synthesis of viral DNA and late gene expression in a dose-dependent manner. The synthesis of alpha- and beta-classes of viral proteins was not affected by the extract. Therefore, it is probable that the smoked tobacco tar extract inhibits the synthesis of viral DNA directly rather than indirectly by depressing early gene expression.

Establishment of two cell lines from hamster buccal pouch tumors induced by topical 7,12-dimethylbenz(a)anthracene and topical DMBA in conjunction with herpes simplex virus infection

Two cell lines designated HBPC-1 and HBPC-2 have been established from hamster buccal pouch tumors induced by topical 7,12-dimethylbenz(a)anthracene (DMBA) and DMBA in conjunction with type 1 herpes simplex virus infection, respectively. The cells are epithelial in morphology, have a doubling time of approximately 18 h, and require bovine serum for optimal growth. The karyotype is aneuploid, with several marker chromosomes, and the cells produce squamous cell carcinomas when transplanted into normal hamster pouch tissues.

The photochemical attachment of the O-glucoside of 3-hydroxykynurenine to alpha-crystallin: a model for lenticular aging

The young human lens contains a small metabolite from tryptophan called the O-glucoside of 3-hydroxykynurenine (3-HKG). Its function is to absorb most radiation between 295 and 400 nm, preventing it from reaching the retina. With age the concentration of this component decreases while the lens crystallins acquire covalently attached chromophores. This study investigates the photochemical attachment of 3-HKG to lens alpha-crystallin. Initial studies showed that alpha-crystallin photolyzed in the presence of 3-HKG developed a fluorescence (emission, 440 nm) and UV-visible spectrum similar to that found in aged human lens proteins. Extensive studies were then performed on the tryptic HPLC maps as monitored by photodiode array and fluorescent detection. Numerous photoproducts with either blue (emission, > 400 nm) or green (emission, > 500 nm) fluorescence were formed in addition to nonfluorescent compounds with absorption maxima above 300 nm. Comparisons were made between these model photoproducts and peptide maps from alpha-crystallin isolated from old human lenses. In terms of retention time and UV-visible spectra at least two of the peptides that appear in the model system are also present in the human samples. It is concluded that one of the aging processes in the human lens is the photochemically induced attachment of 3-HKG to lens proteins.