bluuebunny/crossref_metadata_2025 huggingface dataset:
Wear and Marginal Breakdown of Composites with Various Degrees of Cure
Authors: Ferracane J.L. , Mitchem J.C. , Condon J.R. , Todd R.
Published: January 2009

Loss of anatomical form due to wear has been cited as one factor limiting the clinical use of posterior composites. The physical properties and possibly the wear resistance of composite are influenced by the extent to which it is cured. The aim of this study was to vary degree of conversion (DC) in composites to test the hypothesis that resistance to wear and marginal breakdown could be improved by enhanced curing. A light-cured hybrid composite containing a 50% Bis-GMA/50% TEGDMA resin and 62 vol% of strontium glass (1 to 2 μm) with microfill silica was formulated (Bisco). Composite was placed into two 2.5-mm-diameter cylindrical holes in Co-Cr teeth replacing first and second molars in the mandibular dentures of 50 edentulous patients. The composites were light-cured for different time periods (9 s, 12 s, 25 s, 40 s, and 40 s + 10 min at 120°C) and then polished. The microfill Heliomolar was also tested. DC (%) was measured by FTIR and ranged between 55% for 9 s of light-curing and 67% for 40 s of light-curing followed by heat application. Impressions were evaluated at baseline, 6 mo, 1 yr, and 2 yrs. Stone casts were evaluated independently by three observers to determine the % of the total margin exhibiting breakdown. Epoxy replicas were measured with a profilometer for wear. Wear of the hybrid composite at 2 yrs ranged from a high of 144 μm with 9 s of light-curing to a low of 36 μm with 40 s of light-curing followed by heat. Heliomolar exhibited from 11 to 16 μm of wear at 2 yrs. There was a strong negative correlation (r2 = 0.91) between the degree of cure and the abrasive wear of the hybrid composites. Marginal breakdown was negligible for the hybrids, and was reduced for the microfill from 40% to 15% of the margin by heat treatment. This study showed that the resistance to abrasive wear of a dental composite could be improved by enhancement of its degree of conversion.
IL-1α and TNF-α Expression in Early Periapical Lesions of Normal and Immunodeficient Mice
Authors: Fouad A.F.
Published: January 2009

T-helper and B-lymphocytes may contribute to mechanisms that result in bone-resorptive cytokine production in periapical lesions. Mice with severe combined immunodeficiency ( scid) lack functional B- and T-cell immunity. The purpose of this study was to investigate the progression of pulp necrosis and the histomorphometric features of periapical lesions in scid vs. normal mice. The expression of the bone-resorptive cytokines IL-la and TNF-a was also investigated. Sixteen five-week-old homozygous scid mice and 14 normal BALB/cJ mice were used. The pulps of mandibular first molars were exposed for 1, 2, 3, or 4 weeks. Blocks of tissue containing the mandibular teeth and supporting structures were processed for both light microscopic examination and immunohistochemical staining for IL-1α and TNF-α. Central sections were randomized, their images were blindly digitized into a computer, and the areas of the lesions surrounding the distal root apices were measured. The cells that stained positively for the cytokines in the same area of adjacent sections were counted. Pulp necrosis progressed at similar rates in teeth from both strains. A progressive and significant increase in the periapical lesion size in both strains was observed. The scid mice lesions were significantly smaller than the controls at only the three-week period. There was heavy cytokine staining in periapical lesions from both strains, especially in areas that contained a mixed inflammatory infiltrate or fibroblasts. The number of positively staining cells was proportional to the lesion size. Therefore, pulpal and periapical pathosis were independent of the presence of functional T- and B-cells in this model.
Non-coordinate Control of Bone Formation Displayed by Growth Factor Combinations with IGF-I
Authors: Giannobile W.V. , Whitson S.W. , Lynch S.E.
Published: January 2009

Polypeptide growth factors (GFs) promote osteogenesis by enhancing the mitogenesis, migration, and matrix synthesis of osteoblasts. Most previous investigators have evaluated only the effects of single GFs on these parameters. Studies on single GFs might overlook large biological responses comparable with those documented in the cell cycle literature when GFs are used in combinations that interact synergistically. In this study, we screened for synergistic interactions between IGF-I and three additional GFs (PDGF-BB, TGF-β1, and bFGF) on the regulation of bone growth and differentiation. Fetal bovine osteoblasts were assessed for osteoblast mitogenesis, collagenous and non-collagenous protein synthesis, and alkaline phosphatase activity (ALP). Our results show synergistic interactions between IGF-I and the other GFs on osteoblast mitogenic activity and protein synthesis. In contrast to synergistic mitogenic and protein synthesis effects, IGF-I failed to increase ALP activity when combined with TGF-β1, PDGF-BB, and bFGF in bovine osteoblast-like cells.
Remineralization of Enamel Subsurface Lesions by Casein Phosphopeptide-stabilized Calcium Phosphate Solutions
Authors: Reynolds E.C.
Published: January 2009

Casein phosphopeptides (CPP) stabilize amorphous calcium phosphate (ACP), localize ACP in dental plaque, and are anticariogenic in animal and in situ human caries models. In this in vitro study, CPP-stabilized calcium phosphate solutions were shown to remineralize subsurface lesions in human third-molar enamel. Solutions were used to examine the effect of CPP-calcium phosphate concentration on remineralization. Other solutions were used to examine the effect of increasing pH, which decreased the concentrations of free calcium and phosphate ions and increased the level of CPP-bound ACP. Although most of the remineralizing solutions were supersaturated with respect to the amorphous and crystalline calcium phosphate phases, the solutions were stabilized by the CPP such that spontaneous precipitation of calcium phosphate did not occur. After a ten-day remineralization period, enamel lesions were sectioned, subjected to microradiography, and the mineral content determined by microdensitometry. All solutions deposited mineral into the bodies of the lesions, with the 1.0% CPP-calcium phosphate (pH 7.0) solution replacing 63.9 ±20.1% of mineral lost at an averaged rate of 3.9 ± 0.8 x 10-8 mol hydroxyapatite/m2/s. The remineralizing capacity was greater for the solutions with the higher levels of CPP-stabilized free calcium and phosphate ions. Remineralization was not significantly correlated with either the CPP-bound ACP or the degrees of saturation for hydroxyapatite, octacalcium phosphate, or ACP. However, remineralization was significantly correlated with the degree of saturation for dicalcium phosphate dihydrate (CaHPO4.2H2O), but this was attributed to the significant correlation of remineralization with the activity gradients from the solution into the lesion of some calcium phosphate ions and ion pairs, in particular the neutral ion pair CaHPO40. The CPP, by stabilizing calcium phosphate in solution, maintain high-concentration gradients of calcium and phosphate ions and ion pairs into the subsurface lesion and thus effect high rates of enamel remineralization.
Reduced Chlorhexidine Tooth Stain Coverage by Sequential Administration of Monoperoxyphthalic Acid in the Beagle Dog
Authors: Charbonneau D.L. , Snider A.G.
Published: January 2009

Extrinsic tooth stain is sometimes a side-effect observed with the chronic use of chlorhexidine-containing oral care products. This chlorhexidine (CHX)-induced tooth staining is observed both in humans as well as in experimental animals. The present study tested the hypothesis that the sequential administration of monoperoxyphthalic acid (MPA) will reduce the development of chlorhexidine-induced tooth stain coverage in a beagle dog. For this study, dogs were treated with 30 mL of mouthrinse b.i.d. for 28 days. The following treatment groups (n = 12 dogs/group) were tested: water (negative control), 1.0% MPA rinse, 0.12% CHX rinse, and 1.0% MPA rinse followed by 0.12% CHX rinse. The sequential dosing of 1.0% MPA followed by 0.12% CHX resulted in significantly (p ≤ 0.05) less tooth stain than when dogs were dosed with 0.12% CHX alone. Additionally, the sequential dosing of MPA followed by chlorhexidine resulted in a 75% reduction in plaque formation in this model, which was significantly different (p ≤ 0.05) from results with either treatment alone. A further study demonstrated that similar results could be obtained when MPA plus CHX treatments were separated by approximately a five-hour period in an AM and PM schedule. We conclude that the oxidizer, MPA, can significantly reduce tooth stain induced by CHX while enhancing its antiplaque and antigingivitis activity.
Oral Hygiene Habits of 11-year-old Schoolchildren in 22 European Countries and Canada in 1993/1994
Authors: Kuusela S. , Honkala E. , Kannas L. , Tynjala J. , Wold B.
Published: January 2009

This study is part of the Cross-National Survey on Health Behaviour in School-aged Children-a WHO Collaborative Study, which started in 1982. The aim of the study was to describe the oral hygiene habits (toothbrushing and flossing) of 11-year-old schoolchildren in 22 European countries (Austria, Belgium, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greenland, Hungary, Israel, Latvia, Lithuania, Northern Ireland, Norway, Poland, Russia, Scotland, the Slovak Republic, Spain, Sweden, and Wales) and Canada. The data were collected from standardized anonymous questionnaires in school classrooms during the 1993-1994 school year. At least 1300 schoolchildren, representing the whole country, participated in the study in each country. Oral hygiene habits were analyzed according to gender, age, country, school performance, and family economy. The children brushed most favorably in Sweden, Denmark, Germany, Austria, and Norway (83-73% brushed twice a day). More-than-once-a-day toothbrushing was especially uncommon (from 26 to 33%) among boys in Finland, Lithuania, Russia, Estonia, and Latvia. Toothbrushing frequency differed significantly according to school performance in Canada, the Czech Republic, Scotland, Poland, Northern Ireland, and Wales and between different socio-economic groups in Northern Ireland, Wales, the Czech Republic, Scotland, Poland, and Russia. Use of dental floss was rare. In general, flossing was less frequent among boys than among girls. Daily flossing was most common among Canadian adolescents (25%). In conclusion, there are considerable differences in toothbrushing frequency among children in European countries.
Dr. Basil Bibby: Early Fluoride Investigator and Intellectual Provocateur
Authors: Handelman Stanley , Zero Domenick T.
Published: January 2009

Dr. Basil Bibby assumed many roles during hisproductive career as a researcher, teacher, and administrator. Although best known for his research on oral microbiology and on foodstuff as it relates to dental caries, and for fostering the careers of many distinguished researchers, he played an important generative role in determining the local cariostatic effects of fluoride. His seminal work in this area has not received its due because of the mixed success of his initial clinical studies. We hope that a review of his contributions in this area will bring those contributions into focus and illustrate his open personality and multi-dimensional approach to research.
Salivary Cholesterol of Healthy Adults in Relation to Serum Cholesterol Concentration and Oral Health
Authors: Karjalainen S. , Sewón L. , Soderling E. , Larsson B. , Johansson I. , Simell O. , Lapinleimu H. , Seppänen R.
Published: January 2009

Salivary lipids are mostly glandular in origin, but some are believed to diffuse directly from serum. This diffusion and the role of salivary lipids in oral health have scarcely been studied. Therefore, the serum and saliva cholesterol concentrations and oral health were analyzed in a group of healthy adults (n = 139; 64 men and 75 women; 34.2 ± 5.2 yrs). Paraffin-stimulated whole saliva was collected, centrifuged (10,000 x g ; 30 min, 4°C), and lyophilized, and the cholesterol and other neutral lipids were extracted, separated by thin-layer chromatography, and quantified. The mean ± SD (range) of saliva cholesterol concentration was 1.20 ± 0.75 (0.02-5.46) μmol/L, and the saliva cholesterol level of men (1.36 ± 0.85 μmol/L) was significantly higher than that of women (1.06 ± 0.64 μmol/L; p < 0.05). Weak positive correlations between saliva and serum cholesterol concentrations and saliva cholesterol and serum non-high-density lipoprotein cholesterol concentrations were found (r = 0.22, p < 0.05; r = 0.28, p < 0.005, respectively). The saliva cholesterol assay detected subjects with high (≥ 6.5 mmol/L) serum cholesterol values, with sensitivity and specificity values of 100% and 29%, respectively. A positive correlation between the body mass index and the level of saliva cholesterol concentration was also found (r = 0.31 p < 0.01). Oral health, microbial counts, or saliva flow rate revealed no differences in subjects with low and high salivary cholesterol level. We conclude that, in healthy adults, saliva cholesterol concentration reflects serum concentration to some extent and can be used to select individuals with high serum cholesterol levels.
HIV Status and the Risk of Post-extraction Complications
Authors: Dodson T.B.
Published: January 2009

Tooth extraction is commonly performed for patients infected with the human immunodeficiency virus (HIV). We undertook a prospective study to determine if HIV-positive patients had an increased risk for complications following tooth extraction. The study sample was composed of patients who presented for tooth extraction to the outpatient oral/maxillofacial surgery clinic at Grady Memorial Hospital, Atlanta, GA. The predictor variable was HIV status (positive or negative). The outcome variable was the presence or absence of a post-extraction complication. Other study variables were grouped into the following sets: (1) demographic, (2) past medical and social history, (3) clinical, (4) laboratory values, and (5) treatment. Between 11/93 and 4/96, 166 patients were enrolled. The study sample was composed of the 151 patients who completed the study protocol and consisted of 76 HIV-positive and 75 HIV-negative patients. The post-extraction complication rates were 22.3 and 13.3% for the HIV-positive and -negative groups, respectively (relative risk = 1.68, 95% confidence interval = 0.82 to 3.42, p = 0.15). The types of complications that occurred were similar in both groups. While the data suggest an increased rate of post-extraction complications in the HIV-positive group, the difference in complication rates between the two groups was not statistically significant. In addition, the complications were minor, self-limiting, and readily treated. Based on these findings, we believe that tooth extraction is a low-risk procedure in HIV-positive patients. Treatment may be rendered routinely to patients who present on an outpatient basis without the need for an extensive pre-operative work-up, unless otherwise indicated by relevant history.
Smoking, Smoking Cessation, and Tooth Loss
Authors: Krall E.A. , Dawson-Hughes B. , Garvey A.J. , Garcia R.I.
Published: January 2009

Smoking is associated with an increased risk of tooth loss, but it is not known if this risk decreases significantly when individuals quit smoking. The objectives of this study were to describe the rates of tooth loss by smoking status in two populations of medically healthy men and women. Among the men, rates of tooth loss and edentulism in relation to smoking cessation were also evaluated. The subjects were drawn from a group of 584 women (aged 40 to 70) recruited from the Boston, MA, area and a separate population of 1231 male veterans (aged 21 to 75) who participated in the VA Dental Longitudinal Study in Boston. In cross-sectional baseline analyses, current cigarette smokers of either sex had significantly more missing teeth than never-smokers or former smokers. Former smokers and pipe or cigar smokers tended to have an intermediate number of missing teeth. Current male smokers had more teeth with calculus, but the differences in plaque, tooth mobility, probing depth > 2 mm, filled and decayed teeth, and bleeding on probing by smoking history were not significant. Prospective observations of 248 women (mean follow-up time = 6 ± 2 years) and 977 men (mean = 18 ± 7 years) indicated that individuals who continued to smoke cigarettes had 2.4-fold (men) to 3.5-fold risk (women) of tooth loss compared with non-smokers. The rates of tooth loss in men were significantly reduced after they quit smoking cigarettes but remained higher than those in non-smokers. Men who smoked cigarettes had a 4.5-fold increase in risk of edentulism, and this risk also decreased upon smoking cessation. These findings indicate that the risk of tooth loss is greater among cigarette smokers than among non-smokers. Smoking cessation significantly benefits an individual's likelihood of tooth retention, but it may take decades for the individual to return to the rate of tooth loss observed in non-smokers.
Association between Marginal Bone Loss around Osseointegrated Mandibular Implants and Smoking Habits: A 10-year Follow-up Study
Authors: Lindquist L.W. , Carlsson G.E. , Jemt T.
Published: January 2009

While many factors are conceivable, occlusal loading and plaque-induced inflammation are frequently stated as the most important ones negatively affecting the prognosis of oral implants. Currently, little is known about the relative importance of such factors. The aim of this study was to analyze the influence of smoking and other possibly relevant factors on bone loss around mandibular implants. The participants were 45 edentulous patients, 21 smokers and 24 non-smokers, who were followed for a 10-year period after treatment with a fixed implant-supported prosthesis in the mandible. The peri-implant bone level was measured on intraoral radiographs, information about smoking habits was based on a careful interview, and oral hygiene was evaluated from clinical registration of plaque accumulation. Besides standard statistical methods, multiple linear regression models were constructed for estimation of the relative influence of some factors on peri-implant bone loss. The long-term results of the implant treatment were good, and only three implants (1%) were lost. The mean marginal bone loss around the mandibular implants was very small, about 1 mm for the entire 10-year period. It was greater in smokers than in non-smokers and correlated to the amount of cigarette consumption. Smokers with poor oral hygiene showed greater marginal bone loss around the mandibular implants than those with good oral hygiene. Oral hygiene did not significantly affect bone loss in non-smokers. Multivariate analyses showed that smoking was the most important factor among those analyzed for association with peri-implant bone loss. The separate models for smokers and non-smokers revealed that oral hygiene had a greater impact on peri-implant bone loss among smokers than among non-smokers. This study showed that smoking was the most important factor affecting the rate of peri-implant bone loss, and that oral hygiene also had an influence, especially in smokers, while other factors, e.g., those associated with occlusal loading, were of minor importance. These results indicate that smoking habits should be included in analyses of implant survival and peri-implant bone loss.
A Within-subject Comparison of Mandibular Long-bar and Hybrid Implant-supported Prostheses: Psychometric Evaluation and Patient Preference
Authors: Tang L. , Lund J.P. , Taché R. , Clokie C.M.L. , Feine J.S.
Published: January 2009

Although it has been shown that patients are more satisfied with prostheses supported by implants than with conventional dentures, there have been few direct comparisons of the various designs of implant-supported prostheses. This within-subject crossover clinical trial was designed to compare two forms of removable prostheses which are frequently prescribed for the edentulous mandible: a long-bar overdenture supported by 4 implants and a two-implant hybrid overdenture. Sixteen completely edentulous subjects were given a new maxillary conventional denture: Ten of them received the mandibular long-bar prosthesis first and six the hybrid. After a two-month adaptation period, psychometric measures of various aspects of the prostheses and physiological tests of masticatory efficiency were carried out over three weeks. The mandibular prostheses were then changed and the procedures repeated. At the end of the study, subjects were asked to choose the mandibular prosthesis that they wished to keep, and final psychometric measures were taken. In this paper, the results of the psychometric assessment and patient preference are presented. Subjects assessed factors such as general satisfaction, quality of life, stability, retention, comfort, esthetics, ease of cleaning, speaking, and chewing, and how well-chewed foods were before being swallowed. Most of the factors except ease of cleaning and speaking were rated significantly better with long-bar overdentures than with hybrid ones. These results are consistent with the fact that all subjects chose long-bar overdentures, reporting stability, ease of chewing, and comfort as the most important factors influencing their choice. These results suggest that, although subjects assign high ratings for most factors to hybrid overdentures, they find long-bar overdentures to be significantly more stable, comfortable, and easier for chewing.
Computer Intuition: Guiding Scientific Research in Imaging and Oral Implantology
Authors: Almog D.M. , Heisler E.M.
Published: January 2009

As the costs associated with clinical research and new drug development increase, it is incumbent upon us to develop alternative research methodologies. A new Computer Intuition (CI) program identifies literature-based evidence with the potential to generate a hypothesis that is most likely to be clinically confirmed regarding the cause of a disease or the questions being posed. The objective of this study was to demonstrate whether computer intuition can be used to guide scientific research in solving important biomedical questions. The establishment of CI as an alternative research methodology has the potential to accelerate the translation of basic science findings into clinical practice. The specific aim of this study was to develop a CI-driven hypothesis related to the controversial issue debating which radiographic imaging technology is most suitable for diagnostic purposes prior to the placement of oral implants. This hypothesis was then compared, in retrospect, with a known opinion established following a recent literature review on this issue. In his review of the literature, Frederiksen (1995) suggests that multiplanar reformatted computed tomography (CT) is the diagnostic imaging modality of choice prior to implant placement. To compare the CI hypothesis with Frederiksen's (1995) opinion, we subjected 34 relevant papers to CI analysis. The output consisted of clusters of important statements, phrases, and thought processes from the given dataset rated with the greatest potential to generate testable hypotheses. Both CI's output and Frederiksen (1995) indicated that CT scanning is the diagnostic imaging modality of choice prior to implant placement. Although the ultimate utility of CI is dependent on the successful testing of its derived hypothesis, this preliminary retrospective study suggests that CI might be useful in guiding scientific research.
Cloning and Characterization of Porcine Enamelin mRNAs
Authors: Hu C.-C. , Fukae M. , Uchida T. , Qian Q. , Zhang C.H. , Ryu O.H. , Tanabe T. , Yamakoshi Y. , Murakami C. , Dohi N. , Shimizu M. , Simmer J.P.
Published: January 2009

Dental enamel forms by matrix-mediated biomineralization. The components of the developing enamel matrix are generally specific for that matrix. The primary structures of three enamel proteins-amelogenin, tuftelin, and sheathlin (ameloblastin/amelin)—have been derived from cDNA sequences. Here we report the cloning and characterization of mRNA encoding a fourth enamel protein: enamelin. The longest porcine enamelin cDNA clone has 3907 nucleotides, exclusive of the poly(A) tail. The primary structure of the secreted protein is 1104 amino acids in length. Without post-translational modifications, the secreted protein has an isotope-averaged molecular mass of 124.3 kDa and an isoelectric point of 6.5. Polymerase chain-reaction phenotyping of enamelin cDNA suggests that porcine enamelin transcripts are not alternatively spliced and use a single polyadenylation/cleavage site. Immunohistochemical and Western blot analyses with an affinity-purified antipeptide antibody specific for the enamelin carboxyl terminus demonstrate that enamelin is synthesized and secreted by secretory-phase ameloblasts. The parent protein is a 186-kDa glycoprotein that concentrates along the secretory face of the ameloblast Tomes' process. Intact enamelin and proteolytic cleavage products containing its carboxyl terminus are limited to the most superficial layer of the developing enamel matrix, while other enamelin cleavage products are observed in deeper enamel.
Eugenol Activates Ca2+ -permeable Currents in Rat Dorsal Root Ganglion Cells
Authors: Ohkubo T. , Kitamura K.
Published: January 2009

Although little is known about the mechanism of action of eugenol, some related compounds have been compared with capsaicin derivatives in terms of the relationship between their chemical structure and activity. To elucidate whether eugenol and capsaicin act via a common mechanism at the neuronal membrane, we investigated the effects of eugenol on rat DRG neurons using the whole-cell patch-clamp technique. Eugenol (0.125-1 mmol/L) produced an inward current in a concentration-dependent manner. The reversal potential for this inward current was around 0 mV in PSS. In Na+-deficient solutions, the amplitude of the inward current was slightly reduced at negative holding potentials, whereas in Ca2+-free solution, it was markedly reduced at all holding potentials tested. The reversal potential was not changed by superfusion with either solution. Niflumic acid (100 umol/L) produced a significant inhibition of the current without a change in the reversal potential. These results suggest that eugenol activates a Ca2+-permeable channel as well as a Cl- channel. The latter channel may have been activated by the increase in intracellular Ca2+ concentration caused by the activation of the Ca2+-permeable channel. Capsazepine (10 umol/L) partially inhibited the eugenol-induced current and completely inhibited the capsaicin-induced current. Eugenol (1 mmol/L) produced an inward current even after occurrence of desensitization of the capsaicin-induced current had occurred. Our results suggest that eugenol activates a Ca2+-permeable ion channel in rat DRG neurons through two different mechanisms: a capsaicin receptor-mediated pathway and a pathway independent of the capsaicin-receptor.
Measurement of Velopharyngeal Movements Induced by Isolated Stimulation of Levator Veli Palatini and Pharyngeal Constrictor Muscles
Authors: Adachi T. , Kogo M. , Iida S. , Hamaguchi M. , Matsuya T.
Published: January 2009

The levator veli palatini (LVP) and superior pharyngeal constrictor muscles (PC) close the velopharynx. However, for the velopharyngeal movements to be understood in detail, each muscle contraction must be analyzed precisely. This study was performed to clarify the velopharyngeal movement which was induced by a single muscle contraction, LVP or PC. Using a nasopharyngeal fiberscope, we analyzed the velopharyngeal movement associated with the contraction of the LVP and PC muscles in mongrel dogs. To elicit the maximal contraction of each muscle, we applied repetitive electrical stimulation to each peripheral nerve efferent to the LVP or PC muscle. Stimulation with a frequency of 77 Hz and 83 Hz induced maximal tension in the LVP and PC muscles, respectively, in isometric contraction. In a second series of experiments, fiberscopic views of the velopharyngeal movements associated with each muscle's maximal contraction were recorded. The degree of closure was calculated at several sections. The LVP muscle pulled the caudal fourth of the soft palate, while the PC projected the posterior wall at the level of the caudal end of the soft palate. The PC muscle also projected the lateral wall of the velopharynx. The effect of LVP contraction on the lateral wall was very small. These results show that the velopharyngeal movement associated with LVP contraction is very different from that with PC contraction.
A Three-year Clinical Trial of a Combination of Trimetaphosphate and Sodium Fluoride in Silica Toothpastes
Authors: O'Mullane D.M. , Kavanagh D. , Ellwood R.P. , Chesters R.K. , Schafer F. , Huntington E. , Jones P.R.
Published: January 2009

The relative efficacy of NaF silica toothpastes containing 1000 ppm fluoride and 1500 ppm fluoride in the control of dental caries is not clear-cut. Also, it has not been established that incorporation of trimetaphosphate (TMP) improves the anticaries activity of NaF toothpastes. A three-year clinical trial was conducted to test the hypotheses that: (i) the anticaries activity of NaF toothpastes containing 1500 ppm F was greater than that of NaF toothpastes containing 1000 ppm F, and (ii) inclusion of TMP improved the efficacy of NaF silica pastes. Subsidiary aims included determination of whether frequency of toothbrushing and method of rinsing after brushing were correlated with caries increments. The study involved 4196 children aged 11 to 12 years at outset. These participants had been selected from a pool of 7374 potential subjects on the basis of caries experience and dental eruption pattern. They were stratified by sex, examiner, and presence of calculus and caries, and were allocated at random to one of the four toothpastes under study. Using mirror and probe and also FOTI, we carried out clinical examinations at baseline and annually thereafter for 3 yrs. Bitewing radiographs of a subset of children were taken at baseline and at the end of the study. The outcome measure for the study, DMFS increment, was defined as the increase in caries over 3 yrs, taking into account changes occurring on individual tooth surfaces. Data for 3467 subjects were available for analyses at both baseline and year 3 examinations. Radiographs were taken for 1942 subjects at both baseline and year 3 examinations. The mean three-year clinical-only DMFS increment for the subjects using 1500-ppm-NaF pastes was 3.93, which was 6% lower than the corresponding mean of 4.19 for the 1000-ppm-NaF pastes. There was no significant difference between the mean DMFS increment for those using paste with or without TMP. Subjects who claimed to brush more frequently or who claimed not to use a tumbler to rinse after toothbrushing had lower three-year DFMS increments.
Structural and Functional Association between Substance P- and Calcitonin Gene-related Peptide-immunoreactive Nerves and Accessory Cells in the Rat Dental Pulp
Authors: Okiji T. , Jontell M. , Belichenko P. , Dahlgren U. , Bergenholtz G. , Dahlstrom A.
Published: January 2009

Defense mechanisms of the dentin/pulp complex involve a variety of biological systems in which immunocompetent cells, the nervous system, and the vascular supply play important roles. In the present study, pulpal accessory cells were examined regarding (i) their structural relationship to nerves and (ii) how the functional capacities of these cells were affected by neuropeptides. Micro-anatomic association was investigated in the normal rat molar pulp with the use of double-immunofluorescence staining and dual-channel confocal laser scanning microscopy. Examinations of confocal laser scanning microscopic images from single focal planes revealed the presence of apparent contacts between thin, varicose nerve fibers and immunocompetent cells, indicating proximity between these two structures. The close associations were most frequently observed in the para-odontoblastic region of the coronal pulp, where more than 70% of class II antigen-expressing (OX6+) cells showed proximity to nerve fibers immunoreactive to calcitonin gene-related peptide. The corresponding figure for substance P was about 50%. ED2+ macrophages closely associated with nerves were less frequently observed. Functional studies conducted in vitro demonstrated that 10-9 to 10-7 mol/L of substance P significantly increased (p < 0.05), while 10-7 to 10-6 mol/L of calcitonin gene-related peptide suppressed (p < 0.01) proliferation of purified T-lymphocytes stimulated with sub-optimal concentrations of concanavalin A in the presence of rat incisor pulpal cells as accessory cells. These data suggest that pulpal sensory nerve fibers and their products may have an influence upon the immune defense of the dental pulp.
HLA-D Types and Serum IgG Responses to Capnocytophaga in Diabetes and Periodontitis
Authors: Dyer J.K. , Peck M.A. , Reinhardt R.A. , Duckworth W.C. , Booth S.J. , Seymour G.J. , Patil K.D.
Published: January 2009

Serum IgG responses to the cell envelope proteins (CEPs) from Capnocytophaga sputigena, Capnocytophaga ochracea, and Capnocytophaga gingivalis were examined in periodontally healthy and periodontitis subjects, both with and without type 1 diabetes (n = 60). Serum IgG responses to CEPs were determined by immunoblotting with biotin-goat anti-human IgG and an alkaline phosphatasestreptavidin system. Reactivity was analyzed by transmission densitometry, digitization, and computer manipulation. The patients with diabetes showed significantly (p < 0.01) fewer responses to 14 CEPs (from 81 to 10 kDa) from C. sputigena, 5 CEPs (from 90 to 17 kDa) from C. gingivalis, and the 27-kDa CEP from C. ochracea than in the non-diabetic group. The periodontitis patients showed significantly (p < 0.01) fewer responses to the 25-and 11-kDa CEPs from C. sputigena, the 125- and 17-kDa CEPs from C. gingivalis, and the 42-kDa CEP from C. ochracea than in the periodontally healthy group. HLA-DR4, HLA-DR53, and HLA-DQw3 were associated with periodontitis, while only HLA-DR4 was associated with diabetes (p < 0.02). Significant (p < 0.01) correlations were found between HLA-DR2 and IgG reactivity patterns associated with non-diabetics, and between HLA-DR4 and IgG reactivity patterns associated with diabetic and periodontitis subjects. These results indicate that both type 1 diabetics and periodontitis subjects have a depressed IgG antibody profile to Capnocytophaga, which may account for an increased susceptibility to periodontitis infection. Periodontitis in type 1 diabetes may be related more to the HLA-D type and altered immune function than to the diabetes itself.
Prevalence and Depth of Artificial Caries-like Lesions Adjacent to Cavities Prepared in Roots and Restored with a Glass Ionomer or a Dentin-bonded Composite Material
Authors: Gilmour A.S.M. , Edmunds D.H. , Newcombe R.G.
Published: January 2009

One potential advantage of glass-ionomer materials for the treatment of root caries is their ability to release fluoride and so resist cariogenic attack. A commercially available composite material has also been reported to release fluoride which reduced caries lesions in the tooth tissue adjacent to it. The aim of this study was to assess the effectiveness of a conventional glass-ionomer restoration compared with a dentin-bonded, fluoride-releasing, composite restoration when exposed to a microbial artificial caries system. Artificial caries-like lesions produced in relation to the restorations were examined and classified either as outer (surface) lesions or as wall lesions. A split-unit experimental design allowed for within-tooth comparisons of the 2 experimental restorations at different sites on the root surface. These were either totally within the root surface or positioned at the amelo-cemental junction. Outer lesion depths were significantly (p < 0.001) shallower at all sites adjacent to the glass ionomer when compared with the composite restorations. Wall lesions were significantly (p < 0.01) more prevalent adjacent to the composite material. In addition, the cavity margin position significantly (p < 0.05) affected the incidence of wall lesions, particularly in the composite group. In conclusion, glass ionomer was successful in reducing the caries-like lesion production in the adjacent root surface. This resulted from improved marginal integrity and fluoride release from this material when compared with the composite bonding system used.
The Relationship between Clinical Tooth Status and Receipt of Sealants among Child Medicaid Recipients
Authors: Robison V.A. , Rozier R.G. , Weintraub J.A. , Koch G.G.
Published: January 2009

This study investigated the association between caries status and sealant need at a prior survey and subsequent sealant use in a Medicaid program. Clinical data from a 1986-87 statewide epidemiological survey (N = 8026) representative of North Carolina (NC) schoolchildren (grades K-12) were linked with all NC Medicaid dental claims submitted during 1987-92, yielding 570 children in the survey who had at least one dental visit during 1987-1992. From the 570, 390 children were included: 71 who received sealants (S) and 319 who received non-sealant care (NS). Children were excluded based on age, having pre-existing sealants, or having no sealant-eligible molars or premolars. S and NS were compared on baseline dfs, DMFS, and sealant need, controlling for the patient's age, number of visits, and the provider's propensity to seal. At all ages, NS was twice as likely to have had prior dfs or DMFS (OR = 2.04, 95% CI = 1.15, 3.70). The association between sealant receipt and prior sealant need varied by age. At 6 to 11 years, S and NS had equal likelihood of sealant need (OR = 1.41, 95% CI = 0.62, 3.18). At 12 to 15 years, NS had a greater likelihood of sealant need (OR = 6.82, 95% CI = 1.60, 29.08). Caries-free status was associated with subsequent sealant receipt. Prior sealant need caused variability in dentists' decisions, depending on the child's age and past caries experience. Sealants were used infrequently by most providers and for a minority of patients. These findings are important for the Medicaid program and for future non-randomized studies of sealant effectiveness.
Connections between Polarization Curves and Log(ai/aref)-pe Diagram
Authors: Olsson S. , Bergman M. , Marek M. , Berglund A.
Published: January 2009

When reading papers concerning studies of corrosion of dental amalgam and its phases by means of polarization curves, one often finds it difficult to understand the reasons for the chemical reactions proposed from the form of the polarization curve. Thermodynamic data represented in the form of log( ai/ aref)-pe diagrams, i.e., the logarithm of the activity of a metal or an alloy with reference to the activity of the corresponding metal ion, as a function of pe (a recalculated form of the potential), make it possible for one to determine which chemical reactions can occur on the specimen surface or in the solution within the potential difference used in the polarization experiment and to decide which of these reactions is the most probable. The hypothesis examined in this study is that a log( ai/ aref)-pe diagram can be used in the interpretation of polarization curves. Potentiodynamic polarization curves and log( ai/ aref)-pe diagrams were compared for the corrosion of Ag, Hg, and γ1 with and without Sn. It was found that there was a connection between the polarization curves and the log( ai/ aref)-pe diagrams. From the composition of the specimens and the solution and by means of thermodynamic data, pe values for solid corrosion products and relative concentrations of soluble complexes at these pe values were obtained independently of the polarization curves. A much more reliable value for the nobility of metals and alloys was attained by use of the log( ai/ a ref)-pe diagrams than by use of the potential of the starting point of the polarization curves. It was found that pe corresponding to the potential of the starting point of the polarization curves in de-aerated synthetic saliva was obtained about two pe units before pe of the most insoluble solid compound formed on the specimen surface or in the solution.
Cytokine Profiles of Cells Extracted from Humans with Periodontal Diseases
Authors: Gemmell E. , Seymour G.J.
Published: January 2009

FACS analysis was used to determine the percent interferon (IFN)-gamma-, interleukin (IL)-4-, IL-10-, and CD30-positive T-cells extracted from adult periodontitis (AP) and healthy/gingivitis (H/G) subjects. Additionally, the percentages of IL-1β-, IL-10- and IL-12-producing B-cells and macrophages were ascertained. The percent IL-10+ CD8 cells extracted from AP lesions was decreased compared with H/G tissues (p = 0.033), and the percent CD30+ CD4 (p = 0.001) and CD30+ CD8 (p = 0.028) cells was higher in AP than in H/G tissues. The percentages of IL-1β+ macrophages (p = 0.003) and IL-12+ B-cells (p = 0.034) were both higher in AP lesions than in H/G tissues. The specific effect of Porphyromonas gingivalis on the cytokine profiles of peripheral blood mononuclear cells isolated from P. gingival is-infected AP and H/G patients was also determined. While there were no significant differences in the percent cytokine-positive T-cells after stimulation with P. gingival is outer membrane antigens (OM) for 6 days compared with cells incubated in medium only, the percent CD30+ CD4 cells increased significantly (p = 0.047 and p = 0.063 for AP and H/G groups, respectively). There was also an increase in the percent IL-1β+ B-cells from AP patients (p = 0.029), and the percent IL-12+ monocytes from AP and H/G subjects was higher than the percent IL-12+ B-cells, both after stimulation with P. gingivalis OM (p = 0.005 for the AP group and p = 0.058 and therefore not quite significant for the H/G group) and when incubated in medium alone (p = 0.016 and p = 0.015 for AP and H/G groups, respectively). This study has shown that IL-10+ CD8 cells may be significant in gingival lesions, and that CD30+ T-cells indicative of Th2 or Th0 cells may play a role in progressive periodontal disease. This study has also shown that B-cells produce IL-1 in the gingival lesion and that P. gingivalis may be significant in the induction of B-cell-induced IL-1.
Morphometric Analysis of the Primary and Permanent Dentitions in Hemifacial Microsomia: A Controlled Study
Authors: Kim Seow W. , Urban S. , Vafaie N. , Shusterman S.
Published: January 2009

Hemifacial microsomia (HFM), a developmental abnormality involving the first and second branchial arches, is one of the most common craniofacial abnormalities. Although the general presentations of hemifacial microsomia-such as unilateral microtia, macrostomia, and hypoplasia of the mandibular ramus and condyle-are well-known, the effects on the teeth are not well-documented. This study examined the primary and permanent tooth dimensions of dental casts of 50 hemifacial microsomia patients compared with those of 50 normal control patients matched for sex and dental status. The results showed that the mesiodistal dimensions of the mandibular second primary molar and the mandibular permanent first molar teeth on the affected side in hemifacial microsomia were significantly smaller compared with those of control teeth (p < 0.001). Furthermore, in the maxillary and mandibular first permanent molars and the maxillary and mandibular first and second primary molars, the teeth in the apparently "normal" side of hemifacial microsomia were also significantly reduced in the mesiodistal dimensions. Comparison of overall dimensions revealed that all primary and permanent molars in hemifacial microsomia were significantly smaller in the mesiodistal dimensions compared with control teeth. A general gradient effect was observed, with the most posterior tooth in each arch being the most severely affected and no effect being seen in the canines and the incisors. These findings suggest that the dental lamina in hemifacial microsomia is affected, and support the hypothesis that its pathogenesis involves an abnormality of the neural crest. Furthermore, these results also support the concept that hemifacial microsomia is a bilateral rather than a unilateral condition.
A Finite Element Study of Ultrasonic Wave Propagation in a Tooth Phantom
Authors: Ghorayeb S.R. , Xue T. , Lord W.
Published: January 2009

Ultrasound is used extensively in industry for the detection and characterization of defects in critical engineering structures. Similar techniques could be used in dentistry if a thorough understanding of ultrasonic wave propagation in teeth were available. This paper presents a hypothesis that finite element analysis can be used to solve the hyperbolic partial differential equation which governs ultrasonic wave propagation in teeth. A three-layer tooth phantom based on the geometry of a human second molar is used to illustrate the validity of this hypothesis. Simulated wave propagation studies are described for the tooth phantom with a gold crown layer, with an amalgam restoration insertion, and containing a cavity. Results clearly show the finite element code's ability to predict and visualize ultrasonic wave propagation in complex dental structures.
A TEM Study of Two Water-based Adhesive Systems Bonded to Dry and Wet Dentin
Authors: Van Meerbeek B. , Yoshida Y. , Lambrechts P. , Vanherle G. , Duke E.S. , Eick J.D. , Robinson S.J.
Published: January 2009

To keep the exposed collagen scaffold penetrable to resin, it has been recommended that the conditioned dentin surface be maintained in a visibly moist condition, a clinical technique commonly referred to as wet bonding. In this study, resin-dentin interfaces produced with two water-based adhesive systems-OptiBond (OPTI, Kerr) and Scotchbond Multi-Purpose (SBMP, 3M)-were compared by transmission electron microscopy, following the application of either a dry- or a wet-bonding technique. The hypothesis advanced was that the ultramorphology of the hybrid layer would differ depending on which bonding method was applied. A morphologically well-organized hybrid layer of collagen fibrils intermingled with resin in tiny interfibrillar channels was consistently formed by the OPTI system. The SBMP system was found to produce a hybrid layer with a more variable ultrastructure, less distinctly outlined collagen fibrils, and a characteristic electron-dense phase located at its surface. No major differences in hybrid layer ultrastructure were observed when the two adhesive systems investigated were bonded to either dry or wet dentin. When the adhesives were dry-bonded, no ultrastructural evidence of collapsed demineralized collagen, incompletely or not at all infiltrated by resin, could be detected. In addition, when the two adhesives were bonded to wet dentin, no signs of overwetting phenomena, that would have indicated that water was ineffectively removed, were apparent. It has been hypothesized that the amount of water provided with the hydrophilic primer solution of either of the two adhesive systems investigated suffices to re-hydrate and re-expand the gently air-dried and collapsed collagen network. Further research should be directed to determine whether this hypothesized self-rewetting effect can be extrapolated to other adhesive systems that provide water-based primers.