bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Dental Pulp Stem Cells of Human Tooth Germs
Authors: Takeda T. , Tezuka Y. , Horiuchi M. , Hosono K. , Iida K. , Hatakeyama D. , Miyaki S. , Kunisada T. , Shibata T. , Tezuka K.
Published: January 2009

In previous studies, human dental pulp stem cells (hDPSCs) were mainly isolated from adults. In this present study, we characterized hDPSCs isolated from an earlier developmental stage to evaluate the potential usage of these cells for tissue-regenerative therapy. hDPSCs isolated at the crown-completed stage showed a higher proliferation rate than those isolated at a later stage. When the cells from either group were cultured in medium promoting differentiation toward cells of the osteo/odontoblastic lineage, both became alkaline-phosphatase-positive, produced calcified matrix, and were also capable of forming dentin-like matrix on scaffolds in vivo. However, during long-term passage, these cells underwent a change in morphology and lost their differentiation ability. The results of a DNA array experiment showed that the expression of several genes, such as WNT16, was markedly changed with an increasing number of passages, which might have caused the loss of their characteristics as hDPSCs.
AUF1 and HuR Proteins Stabilize Interleukin-8 mRNA in Human Saliva
Authors: Palanisamy V. , Park N.J. , Wang J. , Wong D.T.
Published: January 2009

Human saliva contains thousands of mRNAs, some of which have translational value as diagnostic markers for human diseases. We have found that more than 30% of the mRNAs detected in human saliva contain AU-rich elements (ARE) in their 3′ untranslated regions (3′UTR). Since AREs are known to contribute to RNA turnover by forming complexes with ARE-binding proteins, we hypothesized that salivary mRNA stability is mediated by ARE-binding proteins in human saliva. To test this hypothesis, we monitored the in vitro degradation of a radiolabeled ARE-containing salivary mRNA (IL-8) in salivary protein extracts. The degradation of IL-8 mRNA was accelerated by competition for saliva ARE-binding proteins through the addition of excess unlabeled IL-8 mRNA fragments containing 4 tandem AREs. UV cross-linking and immunoprecipitation experiments revealed 2 ARE-binding proteins, AUF1 and HuR, associated with IL-8 mRNA in saliva. These results demonstrate that ARE-binding proteins contribute to the stability of ARE mRNAs in human saliva.
Influence of the Chemical Structure of Functional Monomers on Their Adhesive Performance
Authors: Van Landuyt K.L. , Yoshida Y. , Hirata I. , Snauwaert J. , De Munck J. , Okazaki M. , Suzuki K. , Lambrechts P. , Van Meerbeek B.
Published: January 2009

Functional monomers in adhesive systems can improve bonding by enhancing wetting and demineralization, and by chemical bonding to calcium. This study tested the hypothesis that small changes in the chemical structure of functional monomers may improve their bonding effectiveness. Three experimental phosphonate monomers (HAEPA, EAEPA, and MAEPA), with slightly different chemical structures, and 10-MDP (control) were evaluated. Adhesive performance was determined in terms of microtensile bond strength of 4 cements that differed only for the functional monomer. Based on the Adhesion-Decalcification concept, the chemical bonding potential was assessed by atomic absorption spectrophotometry of the dissolution rate of the calcium salt of the functional monomers. High bond strength of the adhesive cement corresponded to low dissolution rate of the calcium salt of the respective functional monomer. The latter is according to the Adhesion-Decalcification concept, suggestive of a high chemical bonding capacity. We conclude that the adhesive performance of an adhesive material depends on the chemical structure of the functional monomer.
Relationship between Kinematic Center and TMJ Anatomy and Function
Authors: Gallo L.M. , Gössi D.B. , Colombo V. , Palla S.
Published: January 2009

The kinematic center (KC)—defined by coinciding jaw-opening/-closing and protrusion-retrusion trajectories—has been proposed in the literature as a reference point to represent TMJ movements. In this study, we tested whether the KC lies in a peculiar anatomical point and whether its trajectory reflects intra-articular distance. In 11 asymptomatic individuals (seven females, four males, aged 24–37 yrs), 4 openings/closings and 4 protrusions/retrusions were tracked with dynamic stereometry. In a 3D lattice (0.5 mm grid) constructed solidly around each condyle, the KC was the point with maximal cross-correlation between opening-closing and protrusion-retrusion paths. KC trajectories were more cranial on closing than on opening, consistent with intra-articular distances being smaller on closing than on opening. However, KCs were never located on condylar main axes (distance, 4.5 ± 2.9 mm), nor did they coincide with points best approximating fossa shapes (distance, 12.5 ± 6.4 mm). The kinematic center’s anatomical and functional significance therefore appears to be questionable.
Aspirin Use and Post-operative Bleeding from Dental Extractions
Authors: Brennan M.T. , Valerin M.A. , Noll J.L. , Napeñas J.J. , Kent M.L. , Fox P.C. , Sasser H.C. , Lockhart P.B.
Published: January 2009

Aspirin is a common, chronically administered preventive treatment for cardiovascular disease, but is often discontinued prior to invasive dental procedures because of concern for bleeding complications. We hypothesized that aspirin does not cause increased bleeding following a single tooth extraction. Thirty-six healthy persons requiring a tooth extraction were randomized to receive 325 mg/day aspirin or placebo for 4 days. Cutaneous bleeding time (BT) and platelet aggregation tests were obtained prior to extraction. The primary outcome measure, oral BT, and secondary bleeding outcomes were evaluated during and following extraction. No significant baseline differences, except for diastolic blood pressure, were found between groups. There were no differences in oral BT, cutaneous BT, secondary outcome measures, or compliance. Whole-blood aggregation results were significantly different between the aspirin and placebo groups. These findings suggest that there is no indication to discontinue aspirin for persons requiring single-tooth extraction.
Does Removable Partial Denture Quality Affect Individuals’ Oral Health?
Authors: Inukai M. , Baba K. , John M.T. , Igarashi Y.
Published: January 2009

The impact of oral disorders and interventions on individuals’ perceived oral health and oral-health-related quality of life (OHRQoL) is being increasingly recognized as an important health component. This study examined the association between denture quality and OHRQoL in individuals wearing removable partial dentures (RPDs). The study participants were 245 consecutive patients (mean age: 63.3 ± 8.7 yrs) at a university-based prosthodontic clinic who wore RPDs for more than one month. RPD quality and OHRQoL were determined by means of a 100-mm visual analog scale (VAS) and the 49-item Oral Health Impact Profile-Japanese version (OHIP-J49), respectively. Linear regression analysis between RPD quality and OHRQoL revealed that a 10-mm VAS increase in RPD quality rating was related to −2.8 OHIP-J49 units (95% confidence interval: −4.5 to −1.1, p = 0.001), which represents an improvement in OHRQoL. The results suggest that RPD quality influences individuals’ OHRQoL to a clinically significant extent.
Mechanotransducers in Rat Pulpal Afferents
Authors: Hermanstyne T.O. , Markowitz K. , Fan L. , Gold M.S.
Published: January 2009

The hydrodynamic theory suggests that pain associated with stimulation of a sensitive tooth ultimately involves mechanotransduction as a consequence of fluid movement within exposed dentinal tubules. To determine whether putative mechanotransducers could underlie mechanotransduction in pulpal afferents, we used a single-cell PCR approach to screen retrogradely labeled pulpal afferents. The presence of mRNA encoding BNC-1, ASIC3, TRPV4, TRPA1, the α, β, and γ subunits of ENaC, and the two pore K+ channels (TREK1, TREK2) and TRAAK were screened in pulpal neurons from rats with and without pulpal inflammation. ASIC3, TRPA1, TREK1, and TREK2 were present in ~67%, 64%, 14%, and 10% of pulpal neurons, respectively. There was no detectable influence of inflammation on the proportion of neurons expressing these mechanotransducers. Given that the majority of pulpal afferents express ASIC3 and TRPA1, our results raise the possibility that these channels may be novel targets for the treatment of dentin sensitivity.
In vitro Performance of Nano-heterogeneous Dentin Adhesive
Authors: Ye Q. , Park J.G. , Topp E. , Wang Y. , Misra A. , Spencer P.
Published: January 2009

Water is ubiquitous in the mouths of healthy individuals and routinely interferes with efforts to bond restorations to dental tissues. Our previous studies using tapping-mode atomic force microscopy (TMAFM) have shown that nanophase separation is a general feature of cross-linked polymethacrylates photocured in the presence of water. To explore the relationship between nanophase separation in dentin adhesives and their long-term mechanical properties, we evaluated model adhesives after 3 months of aqueous storage. The degree of contrast in the TMAFM phase image depended on the formulations used, ranging from ‘not observable’ to ‘very strong’. Correspondingly, the mechanical properties of these model adhesives varied from ‘minimal change’ to ‘significant depreciation’. The results support the hypothesis that a high degree of heterogeneity at the nano-scale is associated with poor mechanical durability in these model adhesives.
Systemic Antibiotics and Tooth Loss in Periodontal Disease
Authors: Cunha-Cruz J. , Hujoel P.P. , Maupome G. , Saver B.
Published: January 2009

Systemic antibiotics have been recommended for the treatment of destructive periodontal disease. Our goal was to relate antibiotic use for medical or dental reasons to subsequent tooth loss in a cohort of 12,631 persons with destructive periodontal disease. After adjustment for age, smoking, and other confounders, the dispensing of antibiotics for 1–13 days, 14–20 days, or 21 or more days was not associated with reduced tooth loss [Adjusted rate ratio (RR) = 1.0; 95% Confidence Interval (CI) = 0.8–1.1; RR = 1.2; 95% CI = 0.9–1.4, and RR =1.2, 95% CI =1.0–1.3, respectively]. Numerous subgroup analyses were consistent with these overall null findings, with two exceptions: Longer courses of tetracyclines were associated with reduced tooth loss among persons receiving periodontal care, and penicillin was associated with reduced tooth loss among persons with more severe disease. Long-term, larger randomized trials are needed to provide evidence that antibiotics reduce tooth loss when used in the management of destructive periodontal disease.
Obstructive Sleep apnea Therapy
Authors: Hoekema A. , Stegenga B. , Wijkstra P.J. , van der Hoeven J.H. , Meinesz A.F. , de Bont L.G.M.
Published: January 2009

In clinical practice, oral appliances are used primarily for obstructive sleep apnea patients who do not respond to continuous positive airway pressure (CPAP) therapy. We hypothesized that an oral appliance is not inferior to CPAP in treating obstructive sleep apnea effectively. We randomly assigned 103 individuals to oral-appliance or CPAP therapy. Polysomnography after 8–12 weeks indicated that treatment was effective for 39 of 51 persons using the oral appliance (76.5%) and for 43 of 52 persons using CPAP (82.7%). For the difference in effectiveness, a 95% two-sided confidence interval was calculated. Non-inferiority of oral-appliance therapy was considered to be established when the lower boundary of this interval exceeded −25%. The lower boundary of the confidence interval was −21.7%, indicating that oral-appliance therapy was not inferior to CPAP for effective treatment of obstructive sleep apnea. However, subgroup analysis revealed that oral-appliance therapy was less effective in individuals with severe disease (apnea-hypopnea index > 30). Since these people could be at particular cardiovascular risk, primary oral-appliance therapy appears to be supported only for those with non-severe apnea.
IL-6 Induces Osteoblastic Differentiation of Periodontal Ligament Cells
Authors: Iwasaki K. , Komaki M. , Mimori K. , Leon E. , Izumi Y. , Ishikawa I.
Published: January 2009

Interleukin (IL)-6 has been considered as an osteolytic factor involved in periodontal disease. However, the function of IL-6 in osteoblastic differentiation of periodontal ligament cells is not clear. We examined the effects of IL-6 and its soluble receptor (sIL-6R) on osteoblastic differentiation of periodontal ligament cells. Osteoblastic differentiation was induced by ascorbic acid. Osteoblast markers, including alkaline phosphatase activity and Runx2 gene expression, were examined. The mechanism of action of IL-6 on osteoblastic differentiation was evaluated by insulin-like growth factor (IGF)-I production and specific inhibitors for the IL-6-signaling molecule. IL-6/sIL-6R enhanced alkaline phosphatase activity and Runx2. Alkaline phosphatase activity was reduced by anti-IGF-I antibody. Mitogen-activated protein kinase and Janus protein tyrosine kinase inhibitors diminished alkaline phosphatase induced by IL-6/sIL-6R. We conclude that IL-6/sIL-6R increases ascorbic-acid-induced alkaline phosphatase activity through IGF-I production, implying that IL-6 acts not only as an osteolytic factor, but also as a mediator of osteoblastic differentiation in periodontal ligament cells.
Inorganic Chemistry of Defensive Peroxidases in the Human Oral Cavity
Authors: Ashby M. T.
Published: January 2009

The innate host response system is comprised of various mechanisms for orchestrating host response to microbial infection of the oral cavity. The heterogeneity of the oral cavity and the associated microenvironments that are produced give rise to different chemistries that affect the innate defense system. One focus of this review is on how these spatial differences influence the two major defensive peroxidases of the oral cavity, salivary peroxidase (SPO) and myeloperoxidase (MPO). With hydrogen peroxide (H2O2) as an oxidant, the defensive peroxidases use inorganic ions to produce antimicrobials that are generally more effective than H2O2 itself. The concentrations of the inorganic substrates are different in saliva vs. gingival crevicular fluid (GCF). Thus, in the supragingival regime, SPO and MPO work in unison for the exclusive production of hypothiocyanite (OSCN−, a reactive inorganic species), which constantly bathes nascent plaques. In contrast, MPO is introduced to the GCF during inflammatory response, and in that environment it is capable of producing hypochlorite (OCl−), a chemically more powerful oxidant that is implicated in host tissue damage. A second focus of this review is on inter-person variation that may contribute to different peroxidase function. Many of these differences are attributed to dietary or smoking practices that alter the concentrations of relevant inorganic species in the oral cavity ( e.g.: fluoride, F−; cyanide, CN−; cyanate, OCN−; thiocyanate, SCN−; and nitrate, NO3−). Because of the complexity of the host and microflora biology and the associated chemistry, it is difficult to establish the significance of the human peroxidase systems during the pathogenesis of oral diseases. The problem is particularly complex with respect to the gingival sulcus and periodontal pockets (where the very different defensive stratagems of GCF and saliva co-mingle). Despite this complexity, intriguing in vitro and in vivo studies are reviewed here that reveal the interplay between peroxidase function and associated inorganic chemistry.
Limited Decalcification/Diffusion of Self-adhesive Cements into Dentin
Authors: Monticelli F. , Osorio R. , Mazzitelli C. , Ferrari M. , Toledano M.
Published: January 2009

Resin cement diffusion into dentin may differ as a function of the pre-treatment regimen. Since self-adhesive cements do not require substrate pre-treatment for luting, penetration of and interaction with the underlying dentin are questioned. We hypothesized that differences in the resin cement diffusion into dentin may exist among current commercial adhesive cements. Composite cylinders were luted on mid-coronal dentinal surfaces by an etch-and-rinse cement (Calibra), a self-etching system (Panavia F 2.0), and 4 self-adhesive cements (Multilink Sprint, Rely X Unicem, G-Cem, Bis-Cem). Dentin/cement interfacial characteristics were analyzed by a staining technique (Masson’s trichrome) and by scanning electron microscopy. Conventional acid etching resulted in partially infiltrated adhesive interfaces differing from those achieved with the application of self-etching primer. No hybrid layer and/or resin tag formation was detectable at the interfaces bonded with self-adhesive cements. Limited decalcification/infiltration was observed for self-adhesive cements into the underlying dentin. Self-adhesive cements were not able to demineralize/dissolve the smear layer completely.
Effects of Ultrasound Modes on Mandibular Osteodistraction
Authors: El-Bialy T.H. , Elgazzar R.F. , Megahed E.E. , Royston T.J.
Published: January 2009

Previous studies have shown that therapeutic pulsed ultrasound (pulsed) has superior stimulatory effect on bone fracture healing compared with continuous ultrasound (continuous). Our predictive hypothesis was that pulsed ultrasound can produce better bone formation during mandibular osteodistraction than continuous ultrasound. Thirty-six New Zealand rabbits were divided into 3 groups of 12. Osteodistraction was performed at 3 mm/day for 5 days. Group 1 received pulsed, group 2 received continuous ultrasound, and group 3 was the control group (distraction only). Bone formation was assessed by quantitative bone density (QBD), mechanical testing, and histological examination. In the first 2 wks post-distraction, group 2 showed enhanced bone formation more than group 1 ( p < 0.05); however, in the 3rd and 4th wks, group 1 showed more bone formation than group 2 ( p < 0.05). Earlier stages of bone healing were enhanced more by continuous, whereas late stages were enhanced more by pulsed, ultrasound. Abbreviations: PULSED, low-intensity pulsed ultrasound; CONTINUOUS, low-intensity continuous ultrasound.
siRNA, miRNA, and shRNA: in vivo Applications
Authors: Pushparaj P.N. , Aarthi J.J. , Manikandan J. , Kumar S.D.
Published: January 2009

RNA interference (RNAi), an accurate and potent gene-silencing method, was first experimentally documented in 1998 in Caenorhabditis elegans by Fire et al., who subsequently were awarded the 2006 Nobel Prize in Physiology/Medicine. Subsequent RNAi studies have demonstrated the clinical potential of synthetic small interfering RNAs (siRNAs) or short hairpin RNAs (shRNAs) in dental diseases, eye diseases, cancer, metabolic diseases, neurodegenerative disorders, and other illnesses. siRNAs are generally from 21 to 25 base-pairs (bp) in length and have sequence-homology-driven gene-knockdown capability. RNAi offers researchers an effortless tool for investigating biological systems by selectively silencing genes. Key technical aspects—such as optimization of selectivity, stability, in vivo delivery, efficacy, and safety—need to be investigated before RNAi can become a successful therapeutic strategy. Nevertheless, this area shows a huge potential for the pharmaceutical industry around the globe. Interestingly, recent studies have shown that the small RNA molecules, either indigenously produced as microRNAs (miRNAs) or exogenously administered synthetic dsRNAs, could effectively activate a particular gene in a sequence-specific manner instead of silencing it. This novel, but still uncharacterized, phenomenon has been termed ‘RNA activation’ (RNAa). In this review, we analyze these research findings and discussed the in vivo applications of siRNAs, miRNAs, and shRNAs.
Regional Dynamic Tensile Properties of the TMJ Disc
Authors: Snider G.R. , Lomakin J. , Singh M. , Gehrke S.H. , Detamore M.S.
Published: January 2009

Although the TMJ disc has been well-characterized under tension and compression, dynamic viscoelastic regional and directional variations have heretofore not been investigated. We hypothesized that the intermediate zone under mediolateral tension would exhibit lower dynamic moduli compared with the other regions of the disc under either mediolateral or anteroposterior tension. Specimens were prepared from porcine discs (3 regions/direction), and dynamic tensile sweeps were performed at 1% strain over a frequency range of 0.1 to 100 rad/sec. Generally, the intermediate zone possessed the lowest storage and loss moduli, and the highest loss tangent. This study further accentuates the known distinct character of the intermediate zone by showing for the first time that these differences also extend to dynamic behavior, perhaps implicating the TMJ disc as a structure primarily exposed to predominantly anteroposterior tension via anterior and posterior attachments, with a need for great distension mediolaterally across the intermediate zone.
Tools for Interpreting Large-scale Protein Profiling in Microbiology
Authors: Hendrickson E.L. , Lamont R.J. , Hackett M.
Published: January 2009

Quantitative proteomic analysis of microbial systems generates large datasets that can be difficult and time-consuming to interpret. Fortunately, many of the data display and gene-clustering tools developed to analyze large transcriptome microarray datasets are also applicable to proteomes. Plots of abundance ratio vs. total signal or spectral counts can highlight regions of random error and putative change. Displaying data in the physical order of the genes in the genome sequence can highlight potential operons. At a basic level of transcriptional organization, identifying operons can give insights into regulatory pathways as well as provide corroborating evidence for proteomic results. Classification and clustering algorithms can group proteins together by their abundance changes under different conditions, helping to identify interesting expression patterns, but often work poorly with noisy data such as typically generated in a large-scale proteomic analysis. Biological interpretation can be aided more directly by overlaying differential protein abundance data onto metabolic pathways, indicating pathways with altered activities. More broadly, ontology tools detect altered levels of protein abundance for different metabolic pathways, molecular functions, and cellular localizations. In practice, pathway analysis and ontology are limited by the level of database curation associated with the organism of interest.
Factors Affecting Photopolymerization Stress in Dental Composites
Authors: Pfeifer C.S. , Ferracane J.L. , Sakaguchi R.L. , Braga R.R.
Published: January 2009

Polymerization stress development results from the complex interplay of volumetric shrinkage, reaction kinetics, and viscoelastic properties. The objective of this study was to examine the relationships among volumetric shrinkage, degree of conversion, rate of polymerization (RPmax), and stress development for 2 model bis-GMA-based composites. Three irradiances were used—220, 400, or 600 mW/cm2—with exposure times adjusted to deliver the same radiant energy. Volumetric shrinkage was determined with a mercury dilatometer, degree of conversion and RPmax by differential scanning calorimetry (DSC), and polymerization stress with a low-compliance device ( Sakaguchi et al., 2004b ). Results indicated that polymerization reaction rate and shrinkage were not correlated. Irradiance was directly related to polymerization reaction rate and to stress development. The group with the highest stress/degree of conversion exhibited the lowest RPmax, so it can be assumed, within the limitations of this study, that the conversion was most closely related to stress development.
iNOS -derived Nitric Oxide Modulates Infection-stimulated Bone Loss
Authors: Fukada S.Y. , Silva T.A. , Saconato I.F. , Garlet G.P. , Ávila-Campos M.J. , Silva J.S. , Cunha F.Q.
Published: January 2009

Nitric oxide (NO) derived from inducible nitric oxide synthase (iNOS) plays an important role in host defense, as well as in inflammation-induced tissue lesions. Here we evaluated the role of NO in bone loss in bacterial infection-induced apical periodontitis by using iNOS-deficient mice (iNOS−/−). The iNOS−/− mice developed greater inflammatory cell recruitment and osteolytic lesions than WT mice. Moreover, tartrate-resistant acid-phosphatase-positive (TRAP+) osteoclasts were significantly more numerous in iNOS−/− mice. Furthermore, the increased bone resorption in iNOS−/− mice also correlated with the increased expression of receptor activator NF-kappaB (RANK), stromal-cell-derived factor-1α (SDF-1α/CXCL12), and reduced expression of osteoprotegerin (OPG). These results show that NO deficiency was associated with an imbalance of bone-resorption-modulating factors, leading to severe infection-stimulated bone loss.
Light-transmitting Ability of Marketed Fiber Posts
Authors: Goracci C. , Corciolani G. , Vichi A. , Ferrari M.
Published: January 2009

If proper polymerization of resin-based cements is to be achieved for fiber post luting, light activation is needed for photo-curing agents, recommended for self-curing materials. The study was aimed at verifying whether the light-transmitting ability of marketed fiber posts reflected the manufacturers’ claims for translucency. Ten posts per type were light-irradiated with a curing unit. Spectrophotometric measurements of the amount of photons reaching different post levels were taken. Data were statistically analyzed (linear regression, two-way ANOVA; α = 0.05). No light transmission was recorded through FibreKleer and Tech21 X-OP. For the other posts, light intensity decreased from coronal to apical and rose again at the apical tip, where it peaked for GC Fiber Post, Macrolock Illusion Post, and Radix Fiber Post. Light transmission was significantly higher at the coronal level. A statistically significant difference in translucency was found for Dentin Post X and FRC Postec Plus in comparison with Reforpost, FibreKleer, Tech21 X-OP, and Composipost.
25-year Analysis of a Dental Undergraduate Research Training Program (BSc Dent) at the University of Manitoba Faculty of Dentistry
Authors: Scott J.E. , de Vries J. , Iacopino A.M.
Published: January 2009

Research in the context of the dental school has traditionally been focused on institutional/faculty accomplishments and generating new knowledge to benefit the profession. Only recently have significant efforts been made to expand the overall research programming into the formal dental curriculum, to provide students with a baseline exposure to the research and critical thinking processes, encourage evidence-based decision-making, and stimulate interest in academic/research careers. Various approaches to curriculum reform and the establishment of multiple levels of student research opportunities are now part of the educational fabric of many dental schools worldwide. Many of the preliminary reports regarding the success and vitality of these programs have used outcomes measures and metrics that emphasize cultural changes within institutions, student research productivity, and student career preferences after graduation. However, there have not been any reports from long-standing programs (a minimum of 25 years of cumulative data) that describe dental school graduates who have had the benefit of research/training experiences during their dental education. The University of Manitoba Faculty of Dentistry initiated a BSc Dent program in 1980 that awarded a formal degree for significant research experiences taking place within the laboratories of the Faculty-based researchers and has continued to develop and expand this program. The success of the program has been demonstrated by the continued and increasing demands for entry, the academic achievements of the graduates, and the numbers of graduates who have completed advanced education/training programs or returned to the Faculty as instructors. Analysis of our long-term data validates many recent hypotheses and short-term observations regarding the benefits of dental student research programs. This information may be useful in the design and implementation of dental student research programs at other dental schools.
Methyl Methacrylate Activates the Gsta1 Promoter
Authors: Hattori N. , Suzuki T. , Jinno S. , Okeya H. , Ishikawa A. , Kondo C. , Hayashi T. , Ito M. , Kanamori T. , Kawai T. , Noguchi T.
Published: January 2009

Residual monomers in resin-based biomaterials cause cytotoxicity. We previously showed that methyl methacrylate (MMA) induced mRNA expression of the glutathione S-transferase alpha 1 gene ( Gsta1) located downstream of the cis-acting anti-oxidant responsive element (ARE). Herein, we tested the hypothesis that MMA activated the Gsta1 promoter through the ARE. HepG2 cells were transfected with a luciferase reporter vector containing the ARE and the Gsta1 promoter (−990 to +46 bp) and cultured for 12 hrs with MMA (initial concentration, 10 mM). Analysis of the expressed luciferase activity indicated that MMA activated the promoter 2.6-fold. MMA (from 1 to 30 mM) dose-dependently increased the promoter activity, which reached a plateau between 6 and 12 hrs. In HepG2 cells transfected with a reporter vector containing 2 AREs and a TATA-like promoter, 10 mM MMA increased the reporter expression 2.8-fold. These results suggest that MMA increases Gsta1 transcription through ARE-mediated promoter activation.
Electric Toothbrushes–For Whom are They Designed?
Authors: Ciancio Sebastian
Published: January 2009

Powered toothbrushes were first introduced on a large scale in the early 1960s. However, because of a clear lack of superiority compared with manual brushes, and problems with mechanical breakdowns, their sales decreased significantly. However, recommendation for their use continued in special populations with dexterity and cognition problems. The 1990s ushered in an era of new technology, and studies began to suggest superiority of some powered brushes, particularly those using oscillating-rotating or counter-rotational actions. Some studies have shown interproximal cleansing abilities superior to those of manual brushes and yielding results similar to those achieved with the use of a manual brush and floss. Both controlled and open-labeled studies have suggested that electric brushes improve gingival health with patients who routinely used manual brushes prior to using these new powered brushes, and safety has been clearly established. In recommending powered toothbrushes, practitioners should familiarize themselves with the products available, with the clinical studies supporting their benefits compared with manual brushes, their safety and ease of use, and the patient's economic status.
Clinical Evidence for the Efficacy and Safety of Powered Toothbrushes
Authors: Heasman P.A. , McCracken G.I.
Published: January 2009

Powered toothbrushes are becoming increasingly popular among the general population, and there are many models on the market from which to choose. The design of these toothbrushes is changing constantly, as one would expect with a developing and expanding market, and from the dental professional's standpoint, it is difficult to evaluate products from the literature simply because the designs of clinical trials for powered toothbrushes are so varied. For example, the cohort recruited for testing the products is seldom the same from one study to the next. The aim of this paper is to provide a brief overview of the findings from some of the more contemporary trials of powered toothbrushes and to examine some of the factors that might have an effect on the observations and outcomes.
Models for Assessing Powered Toothbrushes
Authors: Van der Weijden G.A.
Published: January 2009

The continued development of the power toothbrush over the last 25 years has led to some present-day models that demonstrate increased efficacy in plaque removal compared with a manual brush. The wealth of clinical data that supports these claims has a reference to both in vitro and in vivo models. An overview of performance evidence compared with manual toothbrushes must also be considered from a research model view. The issue of power toothbrush safety in relation to soft tissue abrasion will offer an opportunity for the review of the scientific facts behind any fictitious "hype". Specific studies will provide clinical evidence on power toothbrush safety and performance. This paper will consider implications of the evidence for the use of powered toothbrushes in clinical practice and will emphasize the current consensus of clinical opinion in the light of scientific evidence.
Dental Informatics: An Emerging Biomedical Informatics Discipline
Authors: Schleyer T.K.
Published: January 2009

Biomedical informatics is a maturing discipline. During the last forty years, it has developed into a research discipline of significant scale and scope. One of its subdisciplines, dental informatics, is beginning to emerge as its own entity. While there is a growing cadre of trained dental informaticians, dental faculty and administrators in general are not very familiar with dental informatics as an area of scientific inquiry. Many confuse informatics with information technology (IT), are unaware of its scientific methods and principles, and cannot relate dental informatics to biomedical informatics as a whole. This article delineates informatics from information technology and explains the types of scientific questions that dental and other informaticians typically explore. Scientific investigation in informatics centers primarily on model formulation, system development, system implementation, and the study of effects. Informatics draws its scientific methods mainly from information science, computer science, cognitive science, and telecommunications. Dental informatics shares many types of research questions and methods with its parent discipline, biomedical informatics. However, there are indications that certain research questions in dental informatics require novel solutions that have not yet been developed in other informatics fields.
Dental Informatics: A Work in Progress
Authors: Schleyer T.K.
Published: January 2009

Dental informatics is a young scientific discipline that is undergoing continual maturation. Its literature is estimated to consist of approximately 600 papers published between 1975 and 2003, and it is currently growing at a rate of about 50 papers annually. While interest in the discipline is growing, the number of core contributors to dental informatics research remains relatively small. Two major questions for the discipline are: What are the research challenges that dental informatics faces today? and How can the discipline be strengthened and positioned to maximize its success in addressing those challenges? Progress toward research challenges formulated more than ten years ago has been varied. While many new technologies have become available for clinical dental practice, research, and education, many fundamental problems remain to be addressed with informatics research. Recommendations to augment the research capacity in dental informatics include creating a stronger worldwide dental informatics research community, drawing more biomedical informatics researchers to dental research areas, providing career opportunities for dental informatics researchers, addressing grand challenges together as a community, and recruiting subsequent generations of dental informaticians.
Computational Models of Oral and Craniofacial Development, Growth, and Repair
Authors: Hammond P. , Hutton T. , Maheswaran S. , Modgil S.
Published: January 2009

This paper illustrates how biological and clinical problems stimulate research in biomedical informatics and how such research contributes to their solution. The computational models described use techniques from Logic Programming, Machine Learning, Computer Vision, and Biomathematics. They address problems in the development, growth, and repair of oral and craniofacial tissues arising in cell biology, clinical genetics, and dentistry. At the micro-level, the dynamic interaction of cells in the oral epithelium is modeled. At the macro-level, models are constructed of either the craniofacial shape of an individual or the craniofacial shape differences within and between healthy and congenitally abnormal populations. In between, in terms of scale, there are models of normal dentition and the use of computerized expert knowledge to guide the design of dental prostheses used to restore function in partially edentulous patients.
AIDA: Web Agents in Dental Treatment Planning
Authors: Finkeissen E. , Stamm I. , Müssig M. , Streicher J. , Koke U. , Helmstetter C. , Hassfeld S. , Wetter T.
Published: January 2009

The objective of the AIDA project (Artificial Intelligent Dental Agents, http://aida.uni-hd.de ) is the analysis of dental decision-making, the design of a computer-based decision support system, as well as the testing of the decision structure in interactions with dental experts, practicing dentists, and patients. The planning of the solution alternatives for an individual patient is based on a top-down structure for dental decision-making, aiming at a standardization of the argumentation. From a theoretical point of view, decision support can be provided only for anticipated decisions (planning). Moreover, only parts of these anticipated decisions can be supported. Accordingly, a separation of these partial aspects has to take place before one is able to build decision support systems. For prosthetic dentistry, clinicians have been shown how to use individual patient findings to sketch the possible treatment alternatives and later derive guidelines for the treatment. The planning module for fixed prostheses has already been integrated into a software agent. Planning modules for other types of prostheses are currently specified, implemented, and verified.
Using Information Technology and Community-based Research to Improve the Dental Health-care System
Authors: Atchison K.A.
Published: January 2009

It is commonly acknowledged that the United States’ health-care system produces some of the finest care in the world for some people but fails to meet the needs of others. The Institute of Medicine (IOM) issued six aims for a redesigned health-care system, that it be: safe, effective, patient-centered, timely, efficient, and equitable. The purpose of this paper is to use an ongoing community-based study to illustrate current problems in the provision of oral health services that could be addressed through information technology. Appropriate use of information technology can assist dental schools and clinics in community-based clinical outcomes research needed to assemble the evidence base for improving oral health care. This conference serves as an important steppingstone to establish a means for information technology to improve the community’s oral health.
Overview of Bioinformatics and its Application to Oral Genomics
Authors: Kuo W.P.
Published: January 2009

The “informatics revolution” in both bioinformatics and dental informatics will eventually change the way we practice dentistry. This convergence will play a pivotal role in creating a bridge of opportunity by integrating scientific and clinical specialties to promote the advances in treatment, risk assessment, diagnosis, therapeutics, and oral health-care outcome. Bioinformatics has been an emerging field in the biomedical research community and has been gaining momentum in dental medicine. This area has created a steady stream of large and complex genomic data, which has transformed the way a clinical or basic science researcher approaches genomic research. This application to dental medicine, termed “oral genomics”, can aid in the molecular understanding of the genes and proteins, their interactions, pathways, and networks that are responsible for the development and progression of oral diseases and disorders. As the result of the Human Genome Project, new advances have prompted high-throughput technologies, such as DNA microarrays, which have become accepted tools in the biomedical research community. This manuscript reviews the two most commonly used microarray technologies, basic microarray data analysis, and the results from several ongoing oral cancer genomic studies.
Comparative Genomics and Structure Prediction of Dental Matrix Proteins
Authors: Krishnaraju R.K. , Hart T.C. , Schleyer T.K.
Published: January 2009

Non-collagenous matrix proteins secreted by the ameloblasts (amelogenin) and odontoblasts (osteocalcin) play important roles in the mineralization of enamel and dentin. In this study, comparative genomics approaches were used to identify the functional domains and model the three-dimensional structure of amelogenin and osteocalcin, respectively. Multiple sequence analysis of amelogenin in different species showed a high degree of sequence conservation at the nucleotide and protein levels. At the protein level, motifs (a sequence pattern that occurs repeatedly in a group of related proteins or genes), conserved domains, secondary structural characteristics, and functional sites of amelogenin from lower phyla were similar to those of the higher-level mammals, reflecting the high degree of sequence conservation during vertebrate evolution. Osteocalcin, produced by both odontoblasts and osetoblasts, also showed sequence similarity between species. Three-dimensional structure predictions developed by modeling of conserved domains of osteocalcin supported a role for glutamic acid residues in the calcium mineralization process.
Bayesian Machine Learning and Its Potential Applications to the Genomic Study of Oral Oncology
Authors: Sebastiani P. , Yu Y.-H. , Ramoni M.F.
Published: January 2009

With the completion of the Human Genome Project and the growing computational challenges presented by the large amount of genomic data available today, machine learning is becoming an integral part of biomedical research and plays a major role in the emerging fields of bioinformatics and computational biology. This situation offers unparalleled opportunities and unprecedented challenges to machine learning research in general and to Bayesian learning methods in particular. This paper outlines some of the opportunities and the challenges of this endeavor, it describes where the efforts of “cracking the code of life” can most benefit from a Bayesian approach, and it identifies some potential applications of Bayesian machine learning methods to the genomic analysis of squamous cell carcinomas of the head and neck.
Dental Data Mining: Potential Pitfalls and Practical Issues
Authors: Gansky S.A.
Published: January 2009

Knowledge Discovery and Data Mining (KDD) have become popular buzzwords. But what exactly is data mining? What are its strengths and limitations? Classic regression, artificial neural network (ANN), and classification and regression tree (CART) models are common KDD tools. Some recent reports ( e.g., Kattan et al., 1998 ) show that ANN and CART models can perform better than classic regression models: CART models excel at covariate interactions, while ANN models excel at nonlinear covariates. Model prediction performance is examined with the use of validation procedures and evaluating concordance, sensitivity, specificity, and likelihood ratio. To aid interpretation, various plots of predicted probabilities are utilized, such as lift charts, receiver operating characteristic curves, and cumulative captured-response plots. A dental caries study is used as an illustrative example. This paper compares the performance of logistic regression with KDD methods of CART and ANN in analyzing data from the Rochester caries study. With careful analysis, such as validation with sufficient sample size and the use of proper competitors, problems of naïve KDD analyses ( Schwarzer et al., 2000 ) can be carefully avoided.
HIV Pathogenesis: Knowledge Gained after Two Decades of Research
Authors: Levy J.A.
Published: January 2009

Great progress has been made in our understanding of HIV since its initial discovery about 20 years ago. The ability of HIV to infect CD4+ lymphocytes and a wide variety of other cells in the body is appreciated, as is its role in immunologic, gastrointestinal, and brain disorders. HIV enters cells via the CD4 molecule, chemokine co-receptors (CXCR4, CCR5), and other cell-surface proteins. Several accessory virus-associated genes ( e.g., Rev, Tat, Nef) have uncovered unique pathways that can also be observed in normal cells. Recently, the discovery of natural cellular resistant factors (APOBEC3G and TRIM5a) has provided avenues for novel antiviral therapies. Studies of long-term survivors have given insight into immune responses that control HIV and can prevent infection. Neutralizing antibodies and CD8+ cell cytotoxic responses, as well as plasmacytoid dendritic cells and CD8+ cell non-cytotoxic antiviral responses, are adaptive and innate immune activities mediating this anti-HIV effect. HIV vaccine studies have indicated that conventional approaches do not work against this integrated intracellular parasite. While much has been learned about HIV, more details are needed about its infection cycle and its pathologic effects in the body. The past 20 years have yielded important information on HIV/AIDS that should lead to effective anti-HIV therapies and a vaccine.
Dendritic Cells and HIV Infection: Activating Dendritic Cells to Boost Immunity
Authors: Teleshova N. , Kenney J. , Robbiani M.
Published: January 2009

Dendritic cells (DCs) are white blood cells that coordinate innate and adaptive immunity. They are distributed within epithelia and mucosal-associated lymphoid tissues, positioned to entrap incoming pathogens or vaccines. Human immunodeficiency virus (HIV) and the non-human primate equivalent (SIV) exploit DCs to amplify infection, underscoring the need to harness strategies that promote presentation of virus by DCs to stimulate potent anti-viral immunity instead of virus transmission. Two main subsets of DCs need to be considered: myeloid (MDC) and plasmacytoid (PDC) subsets. Using the SIV-macaque system to advance oral vaccine research, we examined macaque PDC and MDC biology, identifying ways to activate DCs and boost antiviral immunity. Immunostimulatory oligodeoxyribonucleotides (ISS-ODNs) stimulated PDC/MDC mixtures to up-regulate co-stimulatory molecule expression and to secrete both IFN-α and IL-12. Additionally, ISS-ODNs augmented SIV-specific IFN-γresponses induced by virus-bearing DCs. ISS-ODN-driven DC activation is being pursued to improve oral/nasopharyngeal mucosal vaccines and therapies against HIV.
Oral Lesions in HIV Infection in Developing Countries: an Overview
Authors: Ranganathan K. , Hemalatha R.
Published: January 2009

HIV infection is a major global health problem affecting developing and developed countries alike. Oral lesions that are associated with this disease are important, since they affect the quality of life of the patient and are useful markers of disease progression and immunosuppression. Oral lesions in HIV infection have been well-documented in developed countries, but there are fewer reports on oral lesions from developing countries. Oral candidiasis is the most common opportunistic infection seen in all continents. Kaposi’s sarcoma has been reported only from Africa and Latin America, while histoplasmosis and penicilliosis were reported in patients with advanced disease from Thailand. HIV-associated salivary gland disease has a high prevalence in Africa and Latin America, especially in the pediatric group. It is clear that there are considerable regional variations in the oral manifestations of HIV infection, depending both on the populations studied and on the clinical expertise available, among other factors. Well-designed and -documented studies are necessary for the correct assessment of the nature and magnitude of the problem in developing countries, if oral health measures are to be effectively formulated for the HIV-infected.