Granulocyte macrophage-colony stimulating factor and keratinocyte growth factor control of early stages of differentiation of oral epithelium.

Oral epithelial differentiation is known to be directed by underlying fibroblasts, but the responsible factor(s) have not been identified. We aimed here to identify fibroblast-derived factors responsible for oral epithelial differentiation. Primary normal human oral keratinocytes and fibroblasts were isolated from healthy volunteers after informed consent (n = 5) and 3D-organotypic (3D-OT) cultures were constructed. Various growth factors were added at a range of 0.1-100 ng/ml. 3D-OTs were harvested after ten days and assessed histologically, by immunohistochemistry and the TUNEL method. Epithelium developed in 3D-OT without fibroblasts showed an undifferentiated phenotype. Addition of granulocyte macrophage-colony stimulating factor (GM-CSF) induced expression of cytokeratin 13 in suprabasal cell layers. Admixture of GM-CSF and keratinocyte growth factor (KGF) induced, in addition, polarization of epidermal growth factor (EGF) receptor and ß1-integrin to basal cell layer and collagen IV deposition. Terminal differentiation with polarization of TUNEL-positive cells to superficial layers occurred only in the presence of fibroblasts in collagen gels either in direct contact or at distance from normal oral keratinocytes. Taken together, these results show that major aspects of oral epithelial differentiation are regulated by the synergic combination of GM-CSF and KGF. However, the terminal stage seems to be controlled by other yet unidentified fibroblast-derived diffusible factor(s).

Predicting intention of Norwegian dental health-care workers to use nanomaterials: An application of the augmented theory of planned behavior.

Due to the rapid development of nanotechnology and its integration into dentistry, there is a need for information on the factors influencing the decision of dental health-care workers to use nanomaterials. Based on a national survey among Norwegian dentists and dental hygienists, this study applied the theory of planned behavior (TPB), augmented with past behavior and perceived risk, to predict the intention to use dental nanomaterials in the future and to assess whether an augmented TPB model operates equivalently across professional groups. Structural equation modelling was used to assess whether the hypothesized model fits the data. Of 1792 eligible participants, 851 responded to an electronic survey. Attitudes and perceived behavioral control had the strongest effect on intention, followed by past behavior and subjective norms. Risk perceptions had an indirect effect on intention. Multigroup comparison confirmed invariance of the model across professional groups. This study supports the validity of the augmented TPB model to explain the intention of Norwegian dentists and dental hygienists to use nanomaterials. The strongest influence on intention is given by the attitudes toward nanomaterials and perceived confidence in their use. The findings of the study have implications for management of the use of nanomaterials in dentistry by policy makers.

Use of nanomaterials in dentistry: covariates of risk and benefit perceptions among dentists and dental hygienists in Norway.

Objective: Focusing dentists and dental hygienists employed in the Public Dental Health Services (PDHSs) in Norway, this study set out to assess whether socio-demographic factors, familiarity with nanotechnology and social trust are associated with dental health care workers' perceived risks and benefits of use of nanomaterials in dentistry and whether those associations varied according to professional status. It was hypothesized that increased knowledge, trust in stakeholders and familiarity with nanomaterials would decrease the risk and increase benefit perceptions among dental health care workers.Methods: Electronic questionnaires were administered to a census of 1792 dentists and dental hygienists.Results: About 64% and 69% of respondents perceived respectively, risk and benefits associated with use of nanomaterials. Multiple variable logistic regression revealed that dentists were more likely than hygienists to perceive risks (OR = 1.9, 95% CI 1.1-3.3) and benefits (OR = 3.6, 95% CI 2.1-6.2). Having experience with dental nanomaterials (OR = 2.2, 95% CI 1.3-3.7) and feeling safe (OR = 6.6, 95% CI 3.1-14.2) increased perceived benefits. Having moderate or much correct knowledge about nanotechnology (OR = 2.3, 95% CI 1.5-3.5) increased the likelihood of perceived risk.Conclusions: Policy makers should consider the factors that influence dental health care workers' risk and benefit perceptions associated with the use of nanomaterials in dentistry.

Knowledge about nanotechnology and intention to use nanomaterials: A comparative study among dental students in Norway and Romania.

BACKGROUND: The introduction of innovative nanotechnologies in medicine and dentistry may initiate a need for curriculum revision at the universities. The aim of this study was to assess dental students' knowledge and attitudes related to nanotechnology. Covariates of students' intention to use nanomaterials in their future dental practice were evaluated using the theory of planned behaviour (TPB). METHODS: Dental students at Norwegian and Romanian Universities were invited to participate. A self-administered structured questionnaire including socio-demographics and Ajzen's TPB components was used. FINDINGS: A total of 212 out of 732 dental students participated in the survey: 52 Norwegian and 160 Romanian. Most students reported to have little knowledge about nanotechnology (Norwegians = 44.2% vs Romanians = 46.9%, P < .05). More than 90% of the students in both countries reported that they wanted to get more information about nanotechnology. Mean knowledge score was similar for Norwegian and Romanian students (4.4 ± 1.7 vs 4.2 ± 1.4, P > .05). Romanian students had more positive attitude, stronger subjective norms and stronger perceived behavioural control towards nanotechnology compared to their Norwegian counterparts. Intention to use nanomaterials in the total sample was most strongly influenced by attitude towards the use of dental nanomaterials (beta = 0.42, P < .001). CONCLUSION: Dental students in Norway and Romania demonstrated limited knowledge about nanotechnology. Intention to use nanomaterials was primarily influenced by attitudes. A clear desire for more information about the application of nanotechnology in dentistry was expressed by the respondents indicating a need for curriculum modification.

Effect of glycerol on reconstructed human oral mucosa.

The majority of severely ill patients experience dry mouth. For institutionalized patients, this condition is commonly treated using glycerol as a lubricant. However, because of its possibly desiccating effect, some countries do not advocate the use of glycerol. This study aimed to investigate dose-dependent effects of glycerol on homeostasis and tissue integrity of in vitro-reconstructed normal human buccal mucosa (RNHBM). Primary keratinocytes and fibroblasts were isolated and expanded from biopsies of mucosa from eight healthy volunteers. Ninety-six samples of RNHBM were prepared and exposed for 24 h to 17%, 42.5%, or 85% glycerol, or to distilled H2 O (control). Sections were stained with haematoxylin and eosin (H&E) to evaluate epithelial thickness or used for immunohistochemistry to measure expression of Ki67 (proliferation), cleaved caspase-3 (apoptosis), and E-cadherin (tissue-integrity). Positive cells and cell layers, as detected by immunohistochemistry, were counted. Epithelial thickness, proliferation, and apoptosis were significantly increased by exposure to 42.5% and 85% glycerol. No significant differences in apoptosis or proliferation were found between controls and RNHBM exposed to 17% glycerol. E-cadherin expression was not significantly affected by exposure to any of the concentrations of glycerol tested. This study shows that glycerol affects tissue homeostasis, but not tissue integrity, of RNHBM at glycerol concentrations above 42.5%.