Dentinal tubules occluded by bioactive glass-containing toothpaste exhibit high resistance toward acidic soft drink challenge.

BACKGROUND: Dentine hypersensitivity is a common problem attributed by patent dentinal tubules. Ingredients incorporated in toothpastes aim to occlude patent dentinal tubules to minimize the dentine hypersensitivity. However, frequent consumption of acidic soft drinks may reverse the dentinal tubules' occlusion. In this in vitro study, the efficacy of dentinal tubules occluded by commercially available toothpastes to withstand different durations of an acidic soft drink challenge was investigated. METHODS: One hundred and twenty dentine discs were divided into three groups. The discs from each group were brushed with toothpaste containing bioactive glass, arginine and control toothpaste. Each group was then divided into four subgroups and exposed to acidic soft drink over four different time durations. RESULTS: The scoring and the percentage of occluded dentinal tubules by Novamin-containing toothpaste was significantly better compared with arginine or the control toothpaste. Acidic soft drink challenge reduced the extent of dentinal tubules occlusion along with time. Dentinal tubules occluded by Novamin-containing toothpaste withstand the acidic challenge comparatively for a longer period. CONCLUSIONS: The findings demonstrated that occlusion of dentinal tubules is more efficient by the bioactive glass-containing toothpaste and thus may contribute to its better resistance to acidic soft drink challenge.

In vitro expression of Candida albicans alcohol dehydrogenase genes involved in acetaldehyde metabolism.

Alcohol consumption is a risk factor for oral cancer, possibly via its conversion to acetaldehyde, a known carcinogen. The oral commensal yeast Candida albicans may be one of the agents responsible for this conversion intra-orally. The alcohol dehydrogenase (Adh) family of enzymes are involved in acetaldehyde metabolism in yeast but, for C. albicans it is not known which family member is responsible for the conversion of ethanol to acetaldehyde. In this study we determined the expression of mRNAs from three C. albicans Adh genes (CaADH1, CaADH2 and CaCDH3) for cells grown in different culture media at different growth phases by Northern blot analysis and quantitative reverse transcription polymerase chain reaction. CaADH1 was constitutively expressed under all growth conditions but there was differential expression of CaADH2. CaADH3 expression was not detected. To investigate whether CaAdh1p or CaAdh2p can contribute to alcohol catabolism in C. albicans, each gene from the reference strain C. albicans SC5314 was expressed in Saccharomyces cerevisiae. Cell extracts from an CaAdh1p-expressing S. cerevisiae recombinant, but not an CaAdh2p-expressing recombinant, or an empty vector control strain, possessed ethanol-utilizing Adh activity above endogenous S. cerevisiae activity. Furthermore, expression of C. albicans Adh1p in a recombinant S. cerevisiae strain in which the endogenous ScADH2 gene (known to convert ethanol to acetaldehyde in this yeast) had been deleted, conferred an NAD-dependent ethanol-utilizing, and so acetaldehyde-producing, Adh activity. We conclude that CaAdh1p is the enzyme responsible for ethanol use under in vitro growth conditions, and may contribute to the intra-oral production of acetaldehyde.

Detection of Candida albicans ADH1 and ADH2 mRNAs in human archival oral biopsy samples.

OBJECTIVES: The aim of this study was to investigate the relationship between expression of Candida albicans alcohol dehydrogenases (ADH) genes in archival formalin-fixed paraffin-embedded (FFPE) samples from biopsies of leukoplakia. MATERIALS AND METHODS: Archival FFPE samples were obtained from four sample groups: normal oral mucosa, non-dysplastic leukoplakia, chronic hyperplastic candidosis (CHC), and non-CHC dysplastic leukoplakia. The presence of C. albicans was determined by periodic acid Schiff staining and by immunocytochemistry. C. albicans ADH1 and ADH2 mRNAs were detected using reverse transcription PCR. RESULTS: Candida albicans was detected in FFPE samples diagnosed as CHC (the histological diagnoses had been made by specialist oral pathologists, using uniform criteria), but not in any other sample group, including the non-dysplastic leukoplakias. RT-PCR confirmed a significant correlation between the expression of CaADH1 mRNA (P = 0.000), but not for CaADH2 mRNA (P = 0.056) in archival FFPE samples (n = 31) from biopsies of leukoplakia. CONCLUSIONS: Candida albicans was the predominant species in the lesions diagnosed as CHC, and the presence of C. albicans in CHC lesions was associated with a high expression of C. albicans ADH1 mRNA. There was no association between the presence of Candida and malignant transformation in the cases examined; however, the number of cases was limited and further studies are needed to further elucidate the role of C. albicans ADH1 in the pathogenesis of oral squamous cell carcinoma.

Some aspects in the control of schistosomosis and soil-transmitted helminthosis in Yemeni children.

OBJECTIVE: Prevalence, intensity and incidence of schistosomosis and soil-transmitted helminthosis among school children in an ignored area in Yemen were determined. The study aimed to investigate the impact of single doses of Praziquantel or Albenedazole or both, relating to sanitary, socioeconomic and behavioral practices on the prevalence and intensity of infections. METHODS: Out of a total number of 897 pupils, 453 were randomly selected from AlMahweet town and 444 from rural surrounding areas. Millipore filtration, modified Kato and precipitation techniques were applied for urine and stool analysis. RESULTS: Prevalence rates were 27% for schistosomosis, 61% for ascariosis, 21% for trichuriosis, 2% for fascilosis, 0.3% for entrobiosis, 0.7% for hook worm infection and 0.2% for strongloydiosis. Factors found confounding the relationship between schistosomosis and residence, under logistic regression analysis, were sex and frequency of water contact. Probability of infection by Bilharzia for boys who reside in rural AlMahweet and visit the water source is 0.52, compared to 0.30 for their mates who reside in AlMahweet town. Odds ratio estimates accounted for via residence was 2.5, via water contact 1.7 and via boys 3.2. With regards to other helminthic infections, availability of latrines remained the only significant factor under ANOVA. CONCLUSION: In conclusion, annual campaigns for treatment as a single control measure can reduce the infection rate of S. mansoni by 62.5%, T. trichura by 48% and A. lumbricoides by 24%. Whereas for S. hematobium the appropriate time interval for intervention should be shortened according to the findings of a properly designed intervention study before used as a single control measure. Since 77% of the children were infected by other helminthes, therefore mass treatment should be extended to cover all children. For those boys in rural AlMahweet who visited the water source during the week before the interview, mass treatment for schistosomosis is recommended since the prediction of infection rate reached 52%.

Racial variations in the extent of tooth root translucency in ageing individuals.

One hundred and ninety-eight single-rooted teeth from individuals aged 21-90 yr of Caucasian, Malay, Chinese Malay and Indian Malay origin were studied. Single or serial longitudinal sections of extracted teeth were cut following dye imbibition of patent dentinal tubules. The extent of sclerosis of apical dentinal tubules was assessed and correlated with the age of the individual. Correlation with age was higher in the Caucasian than the Malay races and within the Malaysian racial groups correlation with age was highest in the Malays and lowest in the Chinese. It is concluded that factors other than age may be important in the formation of sclerotic apical dentine in teeth of different racial origin. The effect of racial origin should be considered when using sclerosis as a means of age determination in forensic cases.

Severe progressive periodontal destruction due to radiation tissue injury.

Cancer radiotherapy to the head and neck region results in short- and long-term radiation tissue injuries. Radiation bone injury is a long-term manifestation which could progress to osteoradionecrosis. A case of radiation tissue injury to the periodontium is presented. The possible pathogenesis of these events is described as they relate to the sequential radiographic changes observed over a period of 6 years until the involved teeth were exfoliated. The post-irradiation management of the teeth with advancing periodontal disease in the path of irradiation was by conservative means, including good personal oral hygiene care, scaling and root planing, periodic chlorhexidine irrigation, and topical fluoride application.