Since the initial observations of oral bacteria within dental plaque by van Leeuwenhoek using his primitive microscopes in 1680, an event that is generally recognized as the advent of oral microbiological investigation, oral microbiology has gone through phases of “reductionism” and “holism”. From the small beginnings of the Miller and Black period, in which microbiologists followed Koch's postulates, took the reductionist approach to try to study the complex oral microbial community by analyzing individual species; to the modern era when oral researchers embrace “holism” or “system thinking”, adopt new concepts such as interspecies interaction, microbial community, biofilms, poly‐microbial diseases, oral microbiological knowledge has burgeoned and our ability to identify the resident organisms in dental plaque and decipher the interactions between key components has rapidly increased, such knowledge has greatly changed our view of the oral microbial flora, provided invaluable insight into the etiology of dental and periodontal diseases, opened the door to new approaches and techniques for developing new therapeutic and preventive tools for combating oral poly‐microbial diseases.
With additional functions of osteocytes being identified, the concept that osteocytes are just “static lacunar‐dwelling cells” is no longer accepted. We reviewed most of the relevant literature on osteocyte's function in the direct remodeling of the perilucunar matrix, discussing the advantages and disadvantages. Special attention was paid to how the negative researchers argue about the “osteocytic osteolysis” principle, and how the positive side addressed the arguments. We also discussed the newly found data of osteocytic remodeling function from our group. With more biotechnology in hand, there is increased excitement in the prospect of now being able to answer the two important questions: do osteocytes have the capability to remove mineral from the perilacunar matrix and if so what are the molecular and cellular mechanisms? do osteocytes have the capability to deposit new mineral on the perilacunar matrix and if so what are the cellular and molecular mechanisms?
To review the perceptions of dental/medical educators and their students in the United States on the adequacy of didactic and clinical preparation to provide service for individuals with disabilities.
An e‐mailed questionnaire with follow‐up was sent to 198 deans of dental/medical schools, 1,628 directors of residency programs in nine medical/dental residency programs, 427 medical students in 12 medical schools, and 368 health related organizations, facilities and programs.
More than half (58%) of the responding deans of medical schools and 50% of the deans of dental schools reported that a curriculum for patients with disabilities was not a high priority at their school. A majority (61%) of deans of medical schools, and 47% of the deans of dental schools, reported that their graduates were competent to treat patients with disabilities. However, majorities of dental/ medical school seniors and graduates expressed inadequate competency in the care of these patients. A majority of the directors of medical/dental residencies indicated a need for additional training for their residents.
There is need for increased didactic and clinical preparation of dental/medical school graduates in the care of individuals with special health needs. The interest expressed by health profession educators in an effort to develop appropriate curriculum modules provides an opportunity to prepare new graduates for the care of an increasing population of individuals with disabilities.
To detect the expression of HSP25 in rat dental follicles both in vivo and vitro, and explore the underlying mechanism of HSP25 on the proliferation and differentiation of rat dental follicle cells (DFCs).
Immunohistochemistry was performed to detect the expression of HSP25 in mandibles of postnatal rats on days 1, 3, 5, 7, 9 and 11 in vivo. In vitro, the expression of HSP25 in DFCs was detected by an indirect immunofluorescence assay. Thiazolyl blue tetrazolium bromide (MTT) assay, flow cytometry and alkaline phosphatase (ALP) assay were used to identify the time‐course effect mediated by different concentrations of recombinant murine HSP25 of 0, 1, 10, 50 and 100 ng/mL on rat DFCs.
Expression of HSP25 was not detected in dental follicles of the rats until day 5 after birth, but became up‐regulated in a time‐dependent manner till day 11. HSP25 was detected in the cytoplasm of cultured rat DFCs. No significant difference could be observed in the proliferation of DFCs after stimulation with different concentrations of HSP25 on days 1, 2 and 3 (P>0.05). HSP25 at concentrations of 50 ng/mL and 100 ng/mL up‐regulated the ALP activity of DFCs on day 9 (P<0.05).
HSP25‐immunoreactivity increased chronologically during the development of dental follicles. The protein had no significant effect on cell proliferation but may play a role in cementoblast/osteoblast differentiation of DFCs.
To investigate the effect of DAPT (γ‐secretase inhibitor) on the growth of human tongue carcinoma cells and to determine the molecular mechanism to enable the potential application of DAPT to the treatment of tongue carcinoma.
Human tongue carcinoma Tca8113 cells were cultured with DAPT. Cell growth was determined using Indigotic Reduction method. The cell cycle and apoptosis were analyzed by flow cytometry. Real‐time PCR and Immuno‐Fluorescence (IF) were employed to determine the intracellular expression levels.
DAPT inhibited the growth of human tongue carcinoma Tca8113 cells by inducing G0–G1 cell cycle arrest and apoptosis. The mRNA levels of Hairy/Enhancer of Split‐1 (Hes‐1), a target of Notch activation, were reduced by DAPT in a dose‐dependent manner. Coincident with this observation, DAPT induced a dose‐dependent promotion of constitutive Caspase‐3 in Tca8113 cells.
DAPT may have a therapeutic value for human tongue carcinoma. Moreover, the effects of DAPT in tumor inhibition may arise partly via the modulation of Notch‐1 and Caspase‐3.
To determine the effect of local simvastatin application on the mRNA expression level of transforming growth factor‐β1 (TGF‐β1), bone morphogenetic protein‐2 (BMP‐2) and vascular endothelial growth factor (VEGF) in the tooth sockets of rat.
Forty‐eight male Wistar rats were randomly divided into experimental and control groups (n=24). Polylactic acid/polyglycolic acid copolymer carriers, with or without simvastatin, were implanted into extraction sockets of right mandibular incisors. The expression of TGF‐β1, BMP‐2 and VEGF mRNA was determined by in situ hybridization in the tooth extraction socket at five days, one week, two weeks and four weeks after implantation.
The fusiform stroma cells in the tooth extraction socket began to express TGF‐β1, BMP‐2 and VEGF mRNA in both experimental and control groups from one week after tooth extraction until the end of experiment. The expression of TGF‐β1 and BMP‐2 mRNA in the experimental group was significantly up‐regulated after one, two and four weeks, and expression of VEGF mRNA was significantly increased after one and two weeks compared with that in the control group.
The findings indicate that local administration of simvastatin can influence alveolar bone remodeling by regulating the expression of a school of growth factors which are crucial to osteogenesis in the tooth extraction socket.
The piezoelectric properties and cytotoxicity of a porous lead‐free piezoelectric ceramic for use as a direct bone substitute were investigated.
Cold isostatic pressing (CIP) was applied to fabricate porous lithium sodium potassium niobate (Li0.06Na0.5K0.44) NbO3 specimens using a pore‐forming method. The morphologies of the CIP‐processed specimens were characterized and compared to those of specimens made by from conventional pressing procedures. The effects of the ceramic on the attachment and proliferation of osteoblasts isolated from the cranium of 1‐day‐old Sprague‐Dawley rats were examined by a scanning electron microscopy (SEM) and methylthiazol tetrazolium (MTT) assay.
The results showed that CIP enhanced piezoelectricity and biological performance of the niobate specimen, and also promoted an extracellular matrix‐like topography of it. In vitro studies showed that the CIP‐enhanced material had positive effects on the attachment and proliferation of osteoblasts.
Niobate ceramic generated by CIP shows a promise for being a piezoelectric composite bone substitute.