bluuebunny/crossref_metadata_2025 huggingface dataset:
Predicting Dental Implant Survival by Use of the Marginal Approach of the Semi-parametric Survival Methods for Clustered Observations
Authors: Chuang S.K. , Tian L. , Wei L.J. , Dodson T.B.
Published: January 2009

The analyses of clustered survival observations within the same subject are challenging. This study's purpose was to compare and contrast predicted dental implant survival estimates assuming the independence or dependence of clustered observations. Using a retrospective cohort composed of 677 patients (2349 implants), we applied an innovative analytic marginal approach to produce point and variance estimates of survival predictions given the covariates smoking status, implant staging, and timing of placement adjusted for clustered observations (dependence method). We developed a second model assuming independence of the clustered observations (naïve method). The 95% confidence intervals for survival prediction point estimates given the naive method were 5.9% to 14.3% more narrow than the dependence method estimates, resulting in an increased risk for type I error and erroneous rejection of the null hypothesis. To obtain statistically valid confidence intervals for survival prediction of the Aalen-Breslow estimates, we recommend adjusting for dependence among clustered survival observations.
Tooth Loss Occurring at a Place Other than a Health-care Facility: 72-month Incidence
Authors: Gilbert G.H. , Duncan R.P. , Rose J.S. , Shelton B.J.
Published: January 2009

Dental care can occur within or outside the formal health-care system. We hypothesized that certain subject characteristics would partly explain one type of dental self-care, non-professional extractions. A representative sample of diverse groups of dentate adults was studied. In-person interviews and clinical examinations were conducted at baseline, 24, 48, and 72 months, with semi-annual telephone interviews in between. Of 699 participants, 291 (42%) reported loss of at least one tooth, of whom 42 (14% of those with tooth loss) reported having lost the tooth at a place other than a health-care facility. Ninety-four percent of non-professionally lost teeth were self-extracted; relatives extracted the remainder. Fifty-eight percent of these teeth were deliberately removed; the remainder came out while subjects were eating or brushing their teeth, or due to injury. Attachment loss and mobility at previous examination were consistent with the occurrence of non-professional extraction. The incidence magnitude was substantive and persistent throughout follow-up.
Quality of RCTs in Periodontology— A Systematic Review
Authors: Montenegro R. , Needleman I. , Moles D. , Tonetti M.
Published: January 2009

Randomization, concealment of treatment allocation, blinding, and patient follow-up are key quality components of randomized controlled trials (RCTs). The objective of this study was to assess the quality of RCTs in periodontology using these evidence-based components. Following a detailed search, screening and quality assessments of RCTs were conducted in duplicate and independently. The results showed that although 91% of trials were described as randomised, adequate methods for randomization and allocation concealment were found in 17% and 7% of studies, respectively. Blinding was adequate for the caregiver in 17% and for the examiner in 55% of studies. A clear accounting of all participants was present in 56% of reports. This rigorous systematic review revealed that the quality of RCTs in periodontology, judged by their publications, frequently does not meet recommended standards. If this quality is reflected in actual study conduct, fundamental errors could have a significant impact on the outcomes of these trials.
Gene Therapy for the Treatment of Oral Squamous Cell Carcinoma
Authors: Xi S. , Grandis J.R.
Published: January 2009

Despite advances in surgery, radiotherapy, and chemotherapy, the survival of patients with oral squamous cell carcinoma has not significantly improved over the past several decades. Treatment options for recurrent or refractory oral cancers are limited. Gene therapy for oral cancer is currently under investigation in clinical trials. The goal of cancer gene therapy is to introduce new genetic material into target cells without toxicity to non-target tissues. This review discusses the techniques used in cancer gene therapy for oral squamous cell carcinoma and summarizes the ongoing strategies that are being evaluated in clinical trials.
Cadherin-related Neuronal Receptors in Incisor Development
Authors: Fukumoto E. , Sakai H. , Fukumoto S. , Yagi T. , Takagi O. , Kato Y.
Published: January 2009

Cadherins are cell adhesion molecules that are critical for tissue development. In this report, we identified members of the cadherin family cadherin-related neuronal receptors (CNRs) 1 and 5 expressed in rat incisors by the differential display method. Quantitative RT-PCR revealed that CNR1 mRNA is expressed in the secretory stage but reduced in the early-maturation stage, while CNR5 mRNA is expressed in both these stages. In situ hybridization showed that strong expression of CNR1 is strong in the secretory stage, but reduced in the early phase and diminished in the late phase of the early-maturation stage. CNR5 mRNA is expressed almost at the same levels in the secretory and in the early phase of the early-maturation stages but is absent in the late phase of the early-maturation stage. Both CNR1 and 5 mRNA are continuously expressed in odontoblasts. Immunohistology showed that CNR proteins are expressed in the secretory and early-maturation stages of ameloblasts, but no protein expression at the late-maturation stage was observed. CNR proteins were continuously expressed in odontoblasts. We found that recombinant CNR1 binds dental epithelial and mesenchymal cells through N-terminal domain EC1 in vitro. These results suggest that CNR1 and CNR5 may play an important role in enamel and dentin formation, probably through cell-cell and/or cell-matrix interactions.
Bone Morphogenetic Protein-2 Inhibits Differentiation and Mineralization of Cementoblasts in vitro
Authors: Zhao M. , Berry J.E. , Somerman M.J.
Published: January 2009

As an approach for improving the outcome and predictability of periodontal regenerative therapies, we have focused on determining the responses of cells within the local environment to putative regenerative factors. This study examined the effects of bone morphogenetic protein-2 (BMP-2) on murine cementoblasts in vitro. Northern blot analysis indicated that BMP-2 decreased mRNA levels of bone sialoprotein and type I collagen dose-dependently (10–300 ng/mL). At low doses, up to 100 ng/mL, BMP-2 had no effect on transcripts for osteocalcin and osteopontin, whereas at 300 ng/mL, BMP-2 greatly increased expression of these two genes. BMP-2 also inhibited cementoblast-mediated mineral nodule formation in a dose-dependent manner (inhibition was noted at 10 ng/mL). Noggin reversed the effects of BMP-2 on gene expression and on mineralization. These findings reflect the diverse responses of periodontal cells to BMP-2 and highlight the need to consider the complexity of factors involved in designing predictable regenerative therapies.
Association between Craniofacial Growth and Urinary Bone Metabolic Markers (Pyridinoline, Deoxypyridinoline) in Growing Rats
Authors: Tanimoto K. , Imada M. , Ohno S. , Sasaki A. , Honda K. , Tanne K.
Published: January 2009

Pyridinoline (Pyr) and deoxypyridinoline (Dpyr) are intermolecular cross-links of mature collagen and reflect the bone turnover. The purpose of this study was to elucidate the association between craniofacial growth and urinary Pyr and Dpyr levels. Lateral cephalograms and 24-hour urine were taken for 7 male rats from 5 to 20 wks old. The urinary Pyr and Dpyr were quantified by high-performance liquid chromatography. The neurocranium and upper viscerocranium exhibited significant increases in size, with the maximum rate at around 6 wks old. The mandible presented more substantial growth, with the maximum change at 8 wks old. The urinary Pyr and Dpyr levels gradually increased and reached the maximum at 8 wks old. No prominent association was found between neurocranial growth and urinary levels of pyridinium cross-links, whereas Pyr and Dpyr levels exhibited similar time-dependent metabolic changes to mandibular growth. In conclusion, it is shown that urinary pyridinium cross-links may be useful for the prediction of mandibular growth.
Long-term Water-aging of Whisker-reinforced Polymer-Matrix Composites
Authors: Xu H.H.K.
Published: January 2009

Long-term water exposure may degrade polymer-matrix composites. This study investigated the water-aging of whisker composites. It was hypothesized that whiskers would provide stable and substantial reinforcement, and that whisker type would affect water-aging resistance. Silica-fused Si3N4 and SiC whiskers were incorporated into a resin. The specimens were tested by three-point flexure and nano-indentation vs. water-aging for 1 to 730 days. After 730 days, SiC composite had a strength (mean ± SD; n = 6) of 185 ± 33 MPa, similar to 146 ± 44 MPa for Si3N4 composite (p = 0.064); both were significantly higher than 67 ± 23 MPa for an inlay/onlay control (p < 0.001). Compared with 1 day, the strength of the SiC composite showed no decrease, while that of the Si3N4 composite decreased. The decrease was due to whisker weakening rather than to resin degradation or interface breakdown. Whisker composites also had higher moduli than the controls. In conclusion, silica-fused whiskers bonded to polymer matrix and resisted long-term water attack, resulting in much stronger composites than the controls after water-aging.
The Effects of Mandibular Two-implant Overdentures on Nutrition in Elderly Edentulous Individuals
Authors: Morais J.A. , Heydecke G. , Pawliuk J. , Lund J.P. , Feine J.S.
Published: January 2009

It is unclear whether mandibular implant overdentures improve the nutritional state of edentulous patients better than conventional dentures. In a randomized clinical trial, we tested for post-treatment differences in nutritional status between patients with mandibular two-implant retained overdentures and those with conventional complete dentures. Edentulous subjects (ages 65–75 yrs) received two-implant mandibular overdentures (IOD, n = 30) or conventional dentures (CD, n = 30). Measures of nutritional state were gathered before and 6 mos after treatment. Significant improvements in anthropometric parameters were detected in the IOD but not in the CD group, for percent body fat (p = 0.011) and skin-fold thickness at the biceps, subscapularis, and abdomen (p < 0.05), with significant decreases in waist circumference (p < 0.0001) and waist-hip ratio (p = 0.001). Significant increases were seen in concentrations of serum albumin (p = 0.015), hemoglobin (p = 0.01), and B12 (p = 0.01). No significant between-group differences were found. These results suggest that low-cost IOD treatment may improve the nutritional state of edentulous people.
Fluorosis Development in Seven Age Cohorts after an 11-month Break in Water Fluoridation
Authors: Burt B.A. , Keels M.A. , Heller K.E.
Published: January 2009

This study used an 11-month break in water fluoridation to identify the time when developing incisors are most sensitive to fluorosis development. The study was based in Durham, NC, where an interruption to water fluoridation occurred between September, 1990, and August, 1991. A total of 1896 children was dentally examined. Fluorosis was measured by the TF index, and parents or guardians completed a questionnaire on demographics and fluoride history. Age cohorts ranged from those born 5 years before the break, to those born 1 year after the resumption of fluoridation. Fluorosis prevalence for seven age cohorts whose birth years ranged from 1985–86 to 1991–92 was 57.1, 62.3, 33.0, 32.3, 39.8, 30.2, and 36.8%, respectively. Children aged from birth to 3 years at the break, and those born 1 year after it, had less fluorosis than those aged 4–5 years at the break.
Resolution of Inflammation: A New Paradigm for the Pathogenesis of Periodontal Diseases
Authors: Van Dyke T. E. , Serhan C.N.
Published: January 2009

The periodontal diseases are infectious diseases caused by predominantly Gram-negative bacteria. However, as our understanding of the pathogenesis of the periodontal diseases grows, it is becoming clear that most of the tissue damage that characterizes periodontal disease is caused by the host response to infection, not by the infectious agent directly. Investigation into the mechanism of action of host-mediated tissue injury has revealed that the neutrophil plays an important role in destruction of host tissues. In this paper, we review the biochemical pathways and molecular mediators that are responsible for regulation of the inflammatory response in diseases such as periodontitis, with a focus on lipid mediators of inflammation. Pro-inflammatory mediators, such as prostaglandins and leukotrienes, are balanced by counter-regulatory signals provided by a class of molecules called lipoxins. The role of lipoxins in the control and resolution of inflammation is discussed, as is the possibility of the development of new therapeutic strategies for the control and prevention of neutrophil-mediated tissue injury in inflammatory diseases like periodontitis.
Transient Co-localization of c-Jun N-terminal Kinase and c-Jun with Heat Shock Protein 70 in Pulp Cells during Apoptosis
Authors: Kitamura C. , Ogawa Y. , Nishihara T. , Morotomi T. , Terashita M.
Published: January 2009

The c-Jun N-terminal kinase (JNK) pathway and heat-shock proteins (HSPs) are involved in stress-induced apoptosis. Here we examined the association of JNK, c-Jun, and anti-apoptotic HSPs with pulp apoptosis during wound healing. In normal pulp, c-Jun was activated only in a few pulp cells, but JNK was not. HSP70 was expressed in the cytoplasm of pulp cells. One day after injury, active JNK and c-Jun were detected in apoptotic pulp cells, whereas HSP70 was detected in non-apoptotic cells. We also found the translocation of HSP70 into nuclei of pulp cells, and co-localization with active JNK and c-Jun. Four days after injury, active JNK and c-Jun disappeared in pulp cells, and HSP70 was relocalized from nuclei to the cytoplasm. These results suggest that the JNK pathway may be one of the compartments inducing apoptosis in pulp cells, and that HSP70 may have an inhibitory role in the apoptosis of pulp cells during wound healing.
Functional Heterogeneity in the Superior Head of the Human Lateral Pterygoid
Authors: Phanachet I. , Whittle T. , Wanigaratne K. , Klineberg I.J. , Sessle B.J. , Murray G.M.
Published: January 2009

The activity of the superior head of the human lateral pterygoid muscle (SHLP) is controversial. Given the non-parallel alignment of some SHLP fibers, the SHLP may be capable of differential activation. The aims were to clarify SHLP activity patterns in relation to location within SHLP. In 18 subjects, SHLP single motor units were intramuscularly recorded at computer-tomography-verified sites during horizontal ( e.g., protrusion) and vertical ( e.g., opening) jaw tasks (recorded by a jaw-tracking device) and at resting postural jaw position. None of 92 units was active at the resting postural position. Medially located units (21) showed activity during contralateral movement, protrusion, and opening; 5 were also active on jaw closing. There was a significant association between unit location and the number of units active during vertical tasks ( i.e., jaw closing and clenching). Analysis of the data suggests differential activation within SHLP and raises the possibility of functional heterogeneity within SHLP.
Rabbit Calvarial Wound Healing by Means of Seeded Caprotite® Scaffolds
Authors: Bidic S.M.S. , Calvert J.W. , Marra K. , Kumta P. , Campbell P. , Mitchell R. , Wigginton W. , Hollinger J.O. , Weiss L. , Mooney M.P.
Published: January 2009

Autologous bone is the most successful bone-grafting material; however, limited supply and donor site morbidity are problematic. Synthetic bone substitutes are effective, but healing is slow and unpredictable. Osseous wound healing may be enhanced if bone substitutes are combined with autologous bone marrow cells. To test this hypothesis, we created 40 calvarial defects in 20 12-week-old New Zealand White rabbits, divided into four groups: (1) unrepaired controls, (2) autologous bone grafts, (3) unseeded Caprotite® (a polymer-ceramic composite) grafts, and (4) Caprotite® grafts seeded with autologous bone marrow stromal cells. CT scans were obtained at 0, 6, and 12 weeks post-operatively, and defects were harvested for histology. Defects repaired with autologous bone had significantly (p < 0.05) more bone than the other three groups, although seeded Caprotite® defects showed different wound-healing sequelae. Results suggest that seeded Caprotite® scaffolds did not significantly enhance osseous defect healing compared with controls.
Four-year Water Degradation of Total-etch Adhesives Bonded to Dentin
Authors: De Munck J. , Van Meerbeek B. , Yoshida Y. , Inoue S. , Vargas M. , Suzuki K. , Lambrechts P. , Vanherle G.
Published: January 2009

Resin-dentin bonds degrade over time. The objective of this study was to evaluate the influence of variables like hybridization effectiveness and diffusion/elution of interface components on degradation. Hypotheses tested were: (1) There is no difference in degradation over time between two- and three-step total-etch adhesives; and (2) a composite-enamel bond protects the adjacent composite-dentin bond against degradation. The micro-tensile bond strength (μTBS) to dentin of 2 three-step total-etch adhesives was compared with that of 2 two-step total-etch adhesives after 4 years of storage in water. Quantitative and qualitative failure analyses were conducted correlating Fe-SEM and TEM. Indirect exposure to water did not significantly reduce the μTBS of any adhesive, while direct exposure resulted in a significantly reduced μTBS of both two-step adhesives. It is concluded that resin bonded to enamel protected the resin-dentin bond against degradation, while direct exposure to water for 4 years affected bonds produced by two-step total-etch adhesives.
Hybridization Efficiency of the Adhesive/Dentin Interface with Wet Bonding
Authors: Wang Y. , Spencer P.
Published: January 2009

Although it is generally proposed that dentin bonding results from adhesive infiltration of superficially demineralized dentin, it is not clear how well the resin monomers seal the dentin collagen fibrils under wet bonding conditions. The aim of this study was to determine the quality and molecular structure of adhesive/dentin (a/d) interfaces formed with wet bonding as compared with adhesive-infiltrated demineralized dentin (AIDD) produced under controlled conditions (optimum hybrid). From each extracted, unerupted human 3rd molar, one fraction was demineralized, dehydrated, and infiltrated with Single Bond (SB) adhesive under optimum conditions; the remaining, adjacent fraction was treated with SB by wet bonding. AIDD and a/d interface sections were stained with Goldner’s trichrome; corresponding sections were analyzed with micro-Raman spectroscopy. The histomorphologic and spectroscopic results suggest that, under wet bonding, the a/d interface is a porous collagen web infiltrated primarily by the hydrolytically unstable HEMA.
Expression of Bone Morphogenetic Proteins and Msx Genes during Root Formation
Authors: Yamashiro T. , Tummers M. , Thesleff I.
Published: January 2009

Like crown development, root formation is also regulated by interactions between epithelial and mesenchymml tissues. Bone morphogenetic proteins (BMPs), together with the transcription factors Msx1 and Msx2, play important roles in these interactions during early tooth morphogenesis. To investigate the involvement of this signaling pathway in root development, we analyzed the expression patterns of Bmp2, Bmp3, Bmp4, and Bmp7 as well as Msx1 and Msx2 in the roots of mouse molars. Bmp4 was expressed in the apical mesenchyme and Msx2 in the root sheath. However, Bmps were not detected in the root sheath epithelium, and Msx transcripts were absent from the underlying mesenchyme. These findings indicate that this Bmp signaling pathway, required for tooth initiation, does not regulate root development, but we suggest that root shape may be regulated by a mechanism similar to that regulating crown shape in cap-stage tooth germs. Msx2 expression continued in the epithelial cell rests of Malassez, and the nearby cementoblasts intensely expressed Bmp3, which may regulate some functions of the fragmented epithelium.
NF-κB Activation and iNOS Expression in the Synovial Membrane of Rat Temporomandibular Joints after Induced Synovitis
Authors: Yamaza T. , Masuda K.F. , Tsukiyama Y. , Nishijima K. , Murakami R. , Kido M.A. , Koyano K. , Tanaka T.
Published: January 2009

NF-κB plays a pivotal role in pathogenesis in general arthritis. However, the participation of NF-κB in inflammation of the temporomandibular joint (TMJ) is poorly understood. We examined NF-κB expression in rat TMJs with synovitis induced by condyle hypermobility. By immunohistochemistry, NF-κB immunoreactivity was found mainly in the cytoplasm, not the nucleus, of the synovial lining cells of induced-synovitis and control TMJs. Southwestern histochemistry, a new method for detecting transcription factors, showed greater NF-κB expression in the nucleus of the synovial lining cells in the hypertrophic synovium than in control synovium. Increased numbers of the synovial lining cells with immunoreactivity for inducible nitric oxide synthase (iNOS), which is transcriptionally regulated by NF-κB, were also seen in the inflamed synovium. These findings indicate that excess mechanical stress increases NF-κB activation in the TMJ and suggest that active NF-κB is involved in the progression of TMJ inflammation.
The Interleukin-1 Polymorphism, Smoking, and the Risk of Periodontal Disease in the Population-based SHIP Study
Authors: Meisel P. , Siegemund A. , Grimm R. , Herrmann F.H. , John U. , Schwahn C. , Kocher T.
Published: January 2009

Several studies have shown a role for interleukin-1 gene cluster polymorphisms in the risk assessment for periodontal diseases. In the Study of Health in Pomerania (SHIP), 3148 subjects were randomly selected from the population and assessed for a broad range of diseases and environmental/behavioral risk factors. From the complete study group in the age 40 to 60 years, N = 1085 subjects were genotyped for the interleukin-1 genotype composite polymorphism in relation to periodontal parameters. The study objective was to elucidate the gene-environment interaction between the risk factors smoking and IL-1 polymorphism. An increased risk of periodontal disease was found for IL-1 genotype-positive smokers: odds ratio adjusted for age, sex, education, and plaque OR = 2.50 (95% C.I. 1.21 to 5.13; p = 0.013). This was not the case with subjects who never smoked: OR = 1.09 (0.73-1.62; p = 0.676). These results support the hypothesis of gene-environmental interaction in periodontitis.
Optimism and Life Satisfaction as Determinants for Dental and General Health Behavior—Oral Health Habits Linked to Cardiovascular Risk Factors
Authors: Ylöstalo P.V. , Ek E. , Laitinen J. , Knuuttila M.L.
Published: January 2009

Oral infections and cardiovascular diseases share common biological and behavioral risk factors. Psychosocial determinants could act as a link between general health behavior and dental health behavior. Our objective was to study optimism and life satisfaction as determinants of general and dental health behavior and to evaluate whether these are connected with cardiovascular risk factors and dental diseases. The 1966 Northern Finland Birth Cohort (N = 12,058) is a general population birth cohort. In a postal questionnaire, respondents (N = 8690) were asked about their health behavior and dental status. Cardiovascular risk factors were assessed in health examinations (N = 6033). Generalized linear regression models were used in analysis. The results showed that health orientation increases with strengthening life satisfaction and optimism. Dental health behavior and general health behavior were associated with both cardiovascular risk factors and self-reported dental diseases, which support the assumption that they share a common behavioral background.
Human Masticatory Muscle Forces during Static Biting
Authors: Nickel J.C. , Iwasaki L.R. , Walker R.D. , McLachlan K.R. , McCall W.D.
Published: January 2009

Muscle forces determine joint loads, but the objectives governing the mix of muscle forces involved are unknown. This study tested the hypothesis that masticatory muscle forces exerted during static biting are consistent with objectives of minimization of joint loads (MJL) or muscle effort (MME). To do this, we compared numerical model predictions with data measured from six subjects. Biting tasks which produced moments on molar and incisor teeth were modeled based on MJL or MME. The slope of predicted vs. electromyographic (EMG) data for an individual was compared with a perfect match slope of 1.00. Predictions based on MME matched best with EMG activity for molar biting (slopes, 0.89-1.16). Predictions from either or both models matched EMG results for incisor biting (best-match slopes, 0.95-1.07). Muscle forces during isometric biting appear to be consistent with objectives of MJL or MME, depending on the individual, biting location, and moment.
Persistent Acute Inflammation at the Implant-Abutment Interface
Authors: Broggini N. , McManus L.M. , Hermann J.S. , Medina R.U. , Oates T.W. , Schenk R.K. , Buser D. , Mellonig J.T. , Cochran D.L.
Published: January 2009

The inflammatory response adjacent to implants has not been well-investigated and may influence peri-implant tissue levels. The purpose of this study was to assess, histomorphometrically, (1) the timing of abutment connection and (2) the influence of a microgap. Three implant designs were placed in the mandibles of dogs. Two-piece implants were placed at the alveolar crest and abutments connected either at initial surgery (non-submerged) or three months later (submerged). The third implant was one-piece. Adjacent interstitial tissues were analyzed. Both two-piece implants resulted in a peak of inflammatory cells approximately 0.50 mm coronal to the microgap and consisted primarily of neutrophilic polymorphonuclear leukocytes. For one-piece implants, no such peak was observed. Also, significantly greater bone loss was observed for both two-piece implants compared with one-piece implants. In summary, the absence of an implant-abutment interface (microgap) at the bone crest was associated with reduced peri-implant inflammatory cell accumulation and minimal bone loss.
Dissociation States of Collagen Functional Groups and their Effects on the Priming Efficacy of HEMA Bonded to Collagen
Authors: Nishiyama N. , Suzuki K. , Nagatsuka A. , Yokota I. , Nemoto K.
Published: January 2009

Applying 2-hydroxyethylmethacrylate (HEMA) solution to etched dentin enhances the bonding of resin to dentin. However, the principal adhesion mechanisms have not yet been identified. In this study, we examined the dissociation states of the collagen functional groups of the side-chain amino acid residues and their effects on the bond strength of resin to etched dentin primed by the HEMA solution. The bond strength was strongly dependent upon the dissociation state of the collagen functional groups. Inhibiting the dissociation of the carboxylic acid or the amine of a collagen functional group resulted in increased bond strength of resin to collagen. By understanding the significance of inhibiting the dissociation state, we can better design and develop more effective and efficient primer and bonding agents.
Shear in Flexure of Fiber Composites with Different End Supports
Authors: Eckrote K.A. , Burstone C.J. , Freilich M.A. , Messer G.E. , Goldberg A.J.
Published: January 2009

The integrity of fiber-reinforced composite (FRC) prostheses is dependent, in part, on flexural rigidity. The object of this study was to determine if the flexure behavior of uniform FRC beams with restrained or simply supported ends and various length/depth (L/d) aspect ratios could be more accurately modeled by correcting for shear. Experimental results were compared with three analytical models. All models were accurate at high L/d ratios, but the shear-corrected model was accurate to the lowest, more clinically relevant, L/d values. In this range, more than 40% of the beam deflection was due to shear.
Hemispheric Dominance of Tongue Control Depends on the Chewing-side Preference
Authors: Shinagawa H. , Ono T. , Ishiwata Y. , Honda E. , Sasaki T. , Taira M. , Iriki A. , Kuroda T.
Published: January 2009

Blood-oxygenation-level-dependent (BOLD)-functional magnetic resonance imaging (fMRI) is known to be a non-invasive technique for studying human brain function. The purpose of this study was to apply BOLD-fMRI to identify brain areas responsible for producing tongue movements and their relation to chewing-side preference in 15 normal right-handed volunteers. A marked increase in BOLD signals was detected in primary sensorimotor cortices upon protrusion and in rightward and leftward tongue movements compared with at rest. In 10 subjects with an evident chewing-side preference, the BOLD signal change in the primary sensorimotor cortex was significantly greater on the side contralateral to the preferred chewing side. The results suggest that there is a relationship between hemispheric dominance and chewing-side preference in primary sensorimotor cortices responsible for tongue movements.
MSX1 and TGFB3 Contribute to Clefting in South America
Authors: Vieira A.R. , Orioli I.M. , Castilla E.E. , Cooper M.E. , Marazita M.L. , Murray J.C.
Published: January 2009

MSX1 and TGFB3 have been proposed as genes in which mutations may contribute to non-syndromic forms of oral clefts; however, an interaction between these genes has not been described. The present study attempts to detect transmission distortion of MSX1 and TGFB3 in 217 South American children from their respective mothers. With transmission disequilibrium test analysis, cleft lip with/without cleft palate, cleft lip with palate plus cleft palate only, and all datasets combined showed evidence of association with MSX1 (p = 0.004, p = 0.037, and p = 0.001, respectively). With likelihood ratio test analysis, “cleft lip only” showed association with MSX1 (p = 0.04) and “cleft palate only” with TGFB3 (p = 0.02). A joint analysis of MSX1 and TGFB3 suggested that there may be an interaction between these two loci to increase cleft susceptibility. These results suggest that MSX1 and TGFB3 mutations make a contribution to clefts in South American populations.
Bone Formation by BMP-7-transduced Human Gingival Keratinocytes
Authors: Rutherford R.B. , Racenis P. , Fatherazi S. , Izutsu K.
Published: January 2009

BMPs are a family of pleiotropic signaling molecules involved at various stages in the formation of bones and teeth. In addition, recombinant BMP can induce bone and dentin regeneration when applied directly to adult tissues. We have shown that fibroblasts transduced ex vivo by BMP cDNA delivered by recombinant adenoviruses induce bone formation and convert to osteoblasts upon implantation in vivo. To determine if this osteogenic capacity was limited to fibroblasts, we found that BMP-7-transduced human oral keratinocyte cells (HOKC) also formed ectopic bone. The ossicles formed by the BMP-7-transduced HOKC were smaller and more dense than those formed by BMP-7-transduced human gingival fibroblasts (HGF). Implanted HOKC were localized adjacent to the developing bone by immunocytochemical detection of keratin expression. However, no bone-like tissue formed when HOKC were implanted into diffusion chambers in vivo. We conclude that BMP-transduced HOKC secrete BMP and form bone in vivo but, unlike BMP-transduced HGF, do not transdifferentiate to osteoblasts.
Regulation of Osteoprotegerin Gene Expression in Dental Follicle Cells
Authors: Wise G.E. , Ren Y. , Yao S.
Published: January 2009

Colony-stimulating factor-one (CSF-1) and parathyroid-hormone-related protein (PTHrP) down-regulate osteoprotegerin (OPG) gene expression in the dental follicle of the rat first mandibular molar. To examine this regulation at the signal transduction level, we treated cultured dental follicle cells with either phorbolmyristate acetate (PMA) or dibutyryl cyclic AMP (dbcAMP) to activate either protein kinase C (PKC) or protein kinase A (PKA). Our results demonstrate that PMA up-regulates OPG gene expression and down-regulates the expression of CSF-1 and the PTHrP receptor (PTHrP-R). Conversely, dbcAMP down-regulates OPG expression and up-regulates CSF-1 and PTHrP-R expression. Immunostaining shows that PMA also increases the steady-state levels of protein. Thus, treatment with agents that affect protein kinase activity also enhance the steady-state mRNA and protein levels of OPG, as well as decreasing the mRNA levels of CSF-1 and PTHrP-R. The PKC-α isoform may be critical in OPG regulation because PKC-α gene expression is enhanced by PMA and reduced by either CSF-1 or PTHrP.
Differences Between Tooth Stimulation and Capsaicin-induced Neurogenic Vasodilatation in Human Gingiva
Authors: Kemppainen P. , Avellan N.-L. , Handwerker H.O. , Forster C.
Published: January 2009

Animal experiments have shown that the application of capsaicin to oral mucosa leads to a neurogenic inflammation associated with blood flow elevations in gingivomucosal tissues. In this investigation, we measured the tooth stimulation and capsaicin-evoked blood flow responses in maxillary gingiva in humans to study whether axon-reflex-mediated vasodilatation crosses the midline of the maxilla. The vasoactive reactions were mapped by laser Doppler imaging. Unilateral stimulation of alveolar mucosa and attached gingiva by capsaicin evoked a distinct neurogenic vasodilatation in ipsilateral gingiva, which rapidly attenuated at the midline. Capsaicin stimulation of alveolar mucosa provoked clear inflammatory reactions. In contrast to capsaicin stimuli, tooth stimulation produced symmetrical vasodilatations bilaterally in the gingiva. The ipsilateral responses were significantly smaller during tooth stimulation than during capsaicin stimuli. Analysis of these data suggests that capsaicin-induced inflammatory reactions in gingivomucosal tissues do not cross the midline in the anterior maxilla. The enhanced reaction found during stimulation of alveolar mucosa indicates that alveolar mucosa is more sensitive to chemical irritants than attached gingiva.
The Effect of High Sugar Intake on the Development of Periradicular Lesions in Rats with Type 2 Diabetes
Authors: Iwama A. , Nishigaki N. , Nakamura K. , Imaizumi I. , Shibata N. , Yamasaki M. , Nakamura H. , Kameyama Y. , Kapila Y.
Published: January 2009

Diabetes mellitus is associated with depression of natural defenses against infection and increases the risk of periodontal disease. However, the effects of diabetes on periradicular tissue, which differs structurally from periodontal tissue, are not known. In this study, we evaluated the effects of type 2 diabetes on the development of periradicular lesions after exposure of the pulp in the left mandibular first molar through the occlusal surface in rats. GK rats with spontaneous non-insulin-dependent diabetes mellitus and Wistar rats (controls) received a normal laboratory diet and either water or a 30% sucrose solution. At both 2 and 4 weeks after pulp exposure, histologic analysis showed that alveolar bone resorption was most severe and the periradicular lesions were largest in diabetic rats given the sucrose solution. These results suggest that the metabolic conditions produced by type 2 diabetes enhance the development of periradicular lesions in rats.
Toothbrushing as Part of the Adolescent Lifestyle Predicts Education Level
Authors: Koivusilta L. , Honkala S. , Honkala E. , Rimpelä A.
Published: January 2009

Socio-economic differences in health and health behavior are well-known. Our hypothesis was that toothbrushing frequency in adolescents predicts their education level in adulthood. The aim was also to study the role of toothbrushing in adolescents’ health-related lifestyle. Data from nationally representative samples of 12- to 16-year-olds (N = 11,149) were linked with register data on the highest level of education attained at age 27–33 years. Adolescents with a low toothbrushing frequency reached only the lowest education levels. School achievement or sociodemographic background only partly accounted for the association. Exploratory factor analysis found four dimensions of health behaviors. At age 12, a low toothbrushing frequency was loaded highly with “street-oriented” behaviors, concentrated around smoking and alcohol use. At ages 14 and 16, it was associated with a “traditional” lifestyle of the less-well-educated. Altogether, a low toothbrushing frequency indicated selection into the less-well-educated stratum of society. This is likely to be reflected in socio-economic health differences in adulthood.
Implant Surface Roughness Affects Osteoblast Gene Expression
Authors: Schneider G.B. , Perinpanayagam H. , Clegg M. , Zaharias R. , Seabold D. , Keller J. , Stanford C.
Published: January 2009

The transcription factor Cbfa1 regulates osteoblast differentiation and expression of genes necessary for the development of a mineralized phenotype. The purpose of this study was to determine if Cbfa1 and BSPII gene expression are influenced by implant surface microtopography. Osteoblasts were cultured on 600-grit (grooved) or sandblasted (roughened) cpTi implant discs. Mineralization was evaluated by Alizarin-Red-S staining. Real Time PCR was used for quantitative analysis of Cbfa1 and BSPII gene expression. Enhanced mineralization was seen in osteoblasts grown on roughened implant surfaces relative to tissue culture plastic. Real Time PCR showed significant (P < 0.05) increases in Cbfa1 gene expression in cells grown on roughened, as compared with grooved, implant surfaces. BSPII gene expression was also increased on rough surfaces in the UMR cells, but was reduced in the rat calvarial osteoblast cultures. These results suggest that osteoblast gene expression and mineralization are affected by roughened implant surface microtopographies during osseointegration of dental implants.
Vanilloid Receptor Expression in the Rat Tongue and Palate
Authors: Kido M.A. , Muroya H. , Yamaza T. , Terada Y. , Tanaka T.
Published: January 2009

Capsaicin, the pungent substance in hot peppers, evokes a sensation of burning pain by stimulating the vanilloid receptor 1 (VR1) on primary afferent neurons. Immunohistochemistry revealed that the taste papillae in the tongue and palate are richly innervated by VR1-immunoreactive nerve fibers. Furthermore, VR1 protein expression was seen in the epithelium facing the oral cavity, although taste cells seemed to be devoid of VR1. The most conspicuous VR1 expression was observed in the epithelial cells of the palatal rugae, although there were no VR1-immunoreactive nerves there. The finding that VR1 is expressed not only in primary afferents but also in oral epithelial cells suggests that it is of great importance in the perception of capsaicin, heat, and acid in the mouth. Since VR1 is known to play a key role in nociception and inflammatory pain, it may be a new target for the treatment of oral pain.
Neuroendocrine-Immune Surveillance of Osteosarcoma: Emerging Hypothesis
Authors: Prolo P. , Chiappelli F. , Bernard G. , Fiala M. , Ibarra A. , Sartori M.L. , Dovio A. , Angeli A.
Published: January 2009

Osteosarcoma is a bone-forming cancer predominantly found in children and adolescents more often than in adults. Osteosarcoma of the gnathic apparatus is relatively rare in the young population, and this condition becomes a concern of clinical dentists for predominantly the middle-aged and aging patient groups. Osteosarcomas are invaded by lymphocytes, which exhibit signs of activation. The immune processes that are engaged within the malignant bone matrix involve the production of cytokines, which regulate the process of apoptotic programed cell death. This paper discusses the mechanisms by which apoptosis of osteosarcoma cells is modulated by the neuroendocrine-immune system, and potential physiological implications.
Class II Antigen-presenting Dendritic Cell and Nerve Fiber Responses to Cavities, Caries, or Caries Treatment in Human Teeth
Authors: Yoshiba K. , Yoshiba N. , Iwaku M.
Published: January 2009

Major histocompatibility complex (MHC) class II molecule-expressing cells are distributed in human dental pulp, and have been shown to accumulate beneath caries lesions. The responses of these cells and nerve fibers were analyzed under 5 different clinical conditions: shallow and deep experimental cavities, active and slow untreated caries, and treated caries. Under deep cavities, class II molecule-expressing dendritic cells displaced the injured odontoblasts during a period of one month, while such a response was not observed in shallow cavities and untreated or treated carious teeth. The class II molecules seen in the neural elements under active caries were no longer detectable in treated carious teeth. However, six months after treatment, clusters consisting of dendritic cells, T-lymphocytes, and nerve fibers still remained locally in the subodontoblastic area. These results indicate that dental pulps respond differently to cavity preparation and restoration between normal and caries conditions, and that immunoresponses persist for many months, even after caries treatment.
Transforming Growth Factor-β and Interleukin 10 in Oral Implant Sites in Humans
Authors: Schierano G. , Bellone G. , Cassarino E. , Pagano M. , Preti G. , Emanuelli G.
Published: January 2009

Cross-talk between cells and cytokines in peri-implant tissue is largely unknown. The immune response in the gingival mucosa appears to favor implant integration over rejection, since titanium-implant-retained overdentures show long-term success. This study evaluates pro-inflammatory (interleukin [IL]-2, interferon [IFN]-γ, IL-12) and anti-inflammatory (IL-4, IL-10, transforming growth factor [TGF]-β1) cytokine mRNA expression and tissue morphometry in peri-implant soft tissue from patients before and during treatment with Brånemark titanium implants. Immediately after treatment with endosseous implant and overdenture, TGF-β1 mRNA increased in peri-implant mucosa specimens; transcript accumulation for IL-10 was elevated at 4 months and decreased dramatically thereafter. Transcripts for IL-2, IFN-γ, IL-12, and IL-4 were absent. Healthy osseointegrated implants showed no histological inflammation in most patients. These findings suggest that newly classified TGF-β and/or IL-10 secreting T regulatory (r)/T helper (h)-3 cells may populate implant insertion sites.
Heterozygous Mutation in the SAM Domain of p63 Underlies Rapp-Hodgkin Ectodermal Dysplasia
Authors: Kantaputra P.N. , Hamada T. , Kumchai T. , McGrath J.A.
Published: January 2009

Several ectodermal dysplasia syndromes, including Ectrodactyly-Ectodermal dysplasia-Clefting (EEC) and Ankyloblepharon-Ectodermal Dysplasia-Clefting (AEC) syndromes, are known to result from mutations in the p63 gene. We investigated whether Rapp-Hodgkin syndrome (RHS) is also caused by mutations in the p63 gene. We identified a heterozygous de novo germline missense mutation, S545P, in the sterile-alpha-motif (SAM) domain of p63, in a Thai patient affected with RHS. This is the first genetic abnormality to be described in RHS. The amino acid substitution is the most downstream missense mutation in p63 reported thus far. Histological assessment of a skin biopsy from the patient’s palm showed hyperkeratosis and keratinocyte cell-cell detachment in the upper layers of the epidermis, along with numerous apoptotic keratinocytes. Collectively, these investigations demonstrate that RHS is also caused by mutations in p63 and that the clinical similarities to AEC syndrome are paralleled by the nature of the inherent mutation.
Osteoblast Precursor Cell Attachment on Heat-treated Calcium Phosphate Coatings
Authors: Yang Y. , Bumgardner J.D. , Cavin R. , Carnes D.L. , Ong J.L
Published: January 2009

The influence of properties of calcium phosphate (CaP) coatings on bone cell activity and bone-implant osseointegration is not well-established. This study investigated the effects of characterized CaP coatings of various heat treatments on osteoblast response. It was hypothesized that heat treatments of CaP coatings alter the initial osteoblast attachment. The 400°C heat-treated coatings were observed to exhibit poor crystallinity and significantly greater phosphate or apatite species compared with as-sputtered and 600°C heat-treated coatings. Similarly, human embryonic palatal mesenchyme (HEPM) cells, an osteoblast precursor cell line, seeded on 400°C heat-treated coatings, exhibited significantly greater cell attachment compared with Ti surfaces, as-sputtered coatings, and 600°C heat-treated coatings. The HEPM cells on Ti surfaces and heat-treated coatings were observed to attach through filopodia, and underwent cell division, whereas the cells on as-sputtered coatings displayed fewer filopodia extensions and cell damage. Analysis of the data suggested that heat treatment of CaP coatings affects cell attachment.
IGF-1 Signaling Enhances Cell Survival in Periodontal Ligament Fibroblasts vs. Gingival Fibroblasts
Authors: Han X. , Amar S.
Published: January 2009

The role of insulin-like growth factors (IGFs) in the regulation of apoptosis has been suggested, yet their impact on specific cells such as periodontal ligament fibroblasts (PDLF) and gingival fibroblasts (GF) remains unknown. The purpose of this study was to test the role of IGF-1 signaling in cell survival in PDLF compared with GF. In periodontal tissue sections, a significantly reduced apoptotic rate was first demonstrated in PDLF compared with GF. In vitro, IGF-1 substantially enhanced cell survival in PDLF compared with GF by the up-regulation of anti-apoptotic molecules and the down-regulation of pro-apoptotic molecules. Furthermore, the differential expression of insulin-like growth factor binding protein 5 (IGFBP-5) was observed in vitro, and its differential distribution was confirmed in vivo. Analysis of the present data suggests an enhanced cell survival in PDLF compared with GF by the up-regulation of IGF-1 signaling pathway.
MG2 and Lactoferrin Form a Heterotypic Complex in Salivary Secretions
Authors: Soares R.V. , Siqueira C.C. , Bruno L.S. , Oppenheim F.G. , Offner G.D. , Troxler R.F.
Published: January 2009

Protein-protein interactions are necessary for homeostasis to be maintained and for biological systems to be integrated. Heterotypic complexes occur in saliva, and a complex between MG2 and SIgA has been suggested to promote microbial clearance from the oral cavity. In this study, we used a peptide display library to investigate previously unrecognized heterotypic complexes involving MG2 and other proteins. The library was panned with MG2 12 times, and analyses of clones identified the sequence Ala-Leu-Leu-Cys-, which occurs in salivary lactoferrin. Blotting experiments confirmed that MG2 and lactoferrin form a heterotypic complex in viro and in vivo. Periodate treatment of MG2 did not affect the interaction. A synthetic lactoferrin peptide containing the motif Ala-Leu-Leu-Cys-blocked the interaction between MG2 and lactoferrin, confirming the specificity of the interaction identified by panning. This complex may enhance the properties of these salivary components in the oral environment.