bluuebunny/crossref_metadata_2025_split huggingface dataset:
Food Cariogenicity in Americans Aged from 9 to 29 Years Assessed in a National Cross-sectional Survey, 1971-74
Authors: Ismail A.I. 
Published: November 2010

The purpose of this study was to investigate the association between the probability of having high DMFT scores and reported consumption of eight food groups. The sample included Americans (aged from 9 to 29 years) examined during the first National Health and Nutrition Examination Survey conducted between 1971 and 1974. Analysis was restricted to comparing those individuals having DMFT scores equal to or above the 80th percentile of the DMFT distribution with those having scores equal to or below the 20th percentile of the distribution. The strongest discriminator between the low- and high-DMFT groups was the between-meal consumption of table sugars and syrups. The between-meal consumption of sugary desserts was also significantly associated with high DMFT scores. Foods to which table sugars are usually added before consumption, such as coffee, chocolate, and tea drinks, were associated with high DMFT scores in the bivariate analysis. When the same-day consumption of table sugars and syrups was accounted for, the associations became nonsignificant. The reported consumption of breakfast cereals, bread, fruit juices, ice cream, and nuts and crackers was not associated with high DMFT scores, perhaps because they were consumed only infrequently.
Antimicrobial Action of New, Proprietary Lining Cements
Authors: McComb D. , Ericson D. 
Published: November 2010

The antibacterial activity of innovative, commercial lining cements was investigated. A liner which contains calcium hydroxide and is polymerized by visible light (Prisma VLC Dycal) and a glass-ionomer lining cement (GC lining cement) were compared with two more es tablished lining cements (Advanced Formula II Dycal and Life). Antibacterial activity and hemolysis-like agar change at 24, 48, and 72 hours were measured on blood agar plates inoculated with Streptococcus mutans KPSK 2 (serotype c), Lactobacillus casei ssp rhamnosus ATCC 11981, and chewing-stimulated saliva. Prisma VLC Dycal did not affect bacteria or agar. The glass-ionomer lining cement, with an acidic pH at setting, had the most pronounced effect on all test organisms and on the agar. Even after 48 hours' setting, it inhibited growth of S. mutans. The control lining cement (AFII Dycal) showed antibacterial activity toward both specific micro-organisms as well as some activity against the salivary organisms. The material Life showed only partial inhibition of microbial growth. For all lining cements, the hemolytic-like agar change correlated with antibacterial effects. The surface pH of the freshly-set cements containing calcium hydroxide was alkaline. It would seem that a simple correlation between high surface pH and antibacterial activity among these cements does not exist. Also, further biological characterization of new lining cements is required to direct their appropriate clinical use.
Bacteriology of Human Gingivitis
Authors: Moore L.V.H. , Moore W.E.C. , Cato E.P. , Smibert R.M. , Burmeister J.A. , Best A.M. , Ranney R.R. 
Published: November 2010

The subgingival bacterial floras of naturally occurring gingivitis in adults and children were characterized and compared with the floras of other periodontal conditions previously studied. The composition of the gingivitis floras was found to be distinct from that of floras associated with health or with moderate, severe, or juvenile periodontitis. There were no major differences between the floras of naturally-occurring gingivitis and the floras of the human experimental gingivitis model. Data indicated that the flora of healthy sites within a mouth is influenced by the number of inflamed sites, which argues against independence of sites bacteriologically. Proportions of ten bacterial species increased in both gingivitis and periodontitis, as compared with health, in both adults and children. These species were found in both affected and unaffected sites of people with gingivitis. The numbers of five other cultivable species and the "large treponeme", which was not cultivated, increased in gingivitis and periodontitis of adults only. Significant differences in non-spirochetal floras between children and adults were not found, although they were in the experimental gingivitis model studied previously. Cultivable spirochetes did differ between children and adults. Children had fewer samples positive for spirochetes, and children's positive samples contained greater proportions of T. socranskii subsp. paredis. Some species that predominate in periodontitis, but which are absent from healthy gingivae, were found as a small percentage of the flora in gingivitis. This suggests that increased serum and blood in the gingival crevice encourage species that relate to periodontitis.
An Investigation into the Fracture Behavior of a Particulate-filled bis-GMA Resin
Authors: Davis D.M. , Waters N.E. 
Published: November 2010

Dental composites are being increasingly used to restore occlusal surfaces of posterior teeth. If these restorations are not to fracture in service, an understanding of their fracture behavior is essential. The fracture parameter used is the stress-intensity factor at crack instability (KIC). This has been calculated by means of the double-torsion test in a mechanical testing machine. The fracture behavior of the composite was studied by varying: the amount of filler (7%, 15%, 26%, and 41% by volume); the surface treatment of the filler (coated or uncoated); the environment (air and water); and the cross-head rate (0.05, 0.5, 5, and 50 mmlmin). Fracture was found to occur in either a continuous (stable) or stick-slip (unstable) manner. The stick-slip behavior was due to blunting of the crack tip, which was controlled by the yield behavior. When there was no significant blunting, continuous crack growth occurred. An unique relationship was found to exist between the yield stress and the stress-intensity factor for all conditions of testing.
Clinical Results After 12 Months from a Study of the Incidence and Progression of Dental Caries in Relation to Consumption of Chewing-gum Containing Xylitol in School Preventive Programs
Authors: Kandelman D. , Gagnon G. 
Published: November 2010

This study was designed to evaluate the effect of chewing-gum containing xylitol on the incidence and the progression of dental caries. A sample of 433 children, aged 8 and 9 years, of low socio-economic status and high caries rate, was divided into two experimental groups (15% or 65% xylitol chewing-gum distributed three times a day at school) and one control group (without chewing-gum). The three groups were exposed to the same basic preventive program. Children who chewed gum had a significantly smaller DMF(S) increment over a 12-month period than did the control group. The former had increments of 1.58 surfaces, compared with 3.28 for the latter. No statistically significant difference, however, was demonstrated between the two experimental groups. The net progression of decay (progressions-reversals) showed a significant difference between the two experimental groups and the control group. In addition, 65% xylitol chewing-gum produced better results than did that containing 15% xylitol, suggesting a dose-response relationship. Chewing xylitol gum had a beneficial effect on the caries process for all types of tooth surfaces, but chewing gum with a higher xylitol content had an additional positive effect on buccolingual surfaces. A questionnaire asking the participants about stomach pain indicated that there was no difference between the experimental and control groups. The feasibility of such a preventive measure has been demonstrated by the excellent level of participation of both children and teachers. This activity could easily be integrated into existing preventive public health programs.
Effects of Rinses with an Acidic Calcium Phosphate Solution on Fluoride Uptake, Caries, and in situ Plaque pH in Rats
Authors: Schreiber C.T. , Shern R.J. , Chow L.C. , Kingman A. 
Published: November 2010

The effects of oral rinses on enamel fluoride uptake, caries, and plaque pH in rats were investigated by use of (1) an acidic calcium phosphate solution (CPS) saturated with dicalcium phosphate dihydrate (DCPD) and (2) a 1% fluoride solution. Osborne-Mendel rats, 19 days of age, were randomly assigned to one of four mouth-rinse treatment groups, with the two consecutively administered rinses being: H2O-H 2O; H2O-F; CPS-H20; and CPS-F. The treatments were administered on days 1 through 4, and the animals were provided with a cariogenic challenge throughout the study. The groups treated with F exhibited significantly higher mean levels of enamel-bound F than did the non-F groups. Furthermore, CPS significantly increased uptake of F by enamel when used as an adjunct to the F treatment. The caries scores of the CPS-F and H2O-F groups were not statistically different; however, a strong negative correlation was observed between enamel F content and caries scores, indicating that as more F was incorporated into the teeth, less caries formation occurred. Despite the significant differences in enamel F and caries scores among some of the treatment groups, post mortem in situ plaque pH drop in response to a sucrose rinse showed no differences among these groups.
Correlations between Gingival Crevicular Fluid Enzymes and the Subgingival Microflora
Authors: Suido H. , Zambon J.J. , Mashimo P.A. , Dunford R. , Genco R.J. 
Published: November 2010

Bacteroides gingivalis is a Gram-negative micro-organism implicated in the pathogenesis of adult periodontitis and producing relatively large amounts of specific enzymes. In the present study, subgingival samples taken from adults with moderate periodontitis were examined for the presence and relative amounts of enzymatic activity toward certain substrates. Enzyme levels were then correlated with clinical periodontal indices and microbiological analysis of subgingival plaque, including darkfield microscopy for bacterial morphotypes and immunofluorescence microscopy for B. gingivalis and Bacteroides intermedius. The results of this study indicate a significant positive correlation between levels of enzyme capable of degrading N-benzoyl-D,L-arginine-β -naphthylamide hydrochloride, and subgingival B. gingivalis (r = 0.55). There was a much lower correlation coefficient between this enzyme activity and subgingival B. intermedius (r = 0.26). Statistically significant (p < 0.01) positive correlations were also demonstrated between total bacterial cell counts and levels of enzymatic activity against N-benzoyl-D,L-arginine-B-naphthylamide hydrochloride (r = 0.76), N-carbobenzoxy-glycyl-glycyl-L-arginine-β-naphthylamide hydrochloride (r = 0. 72), and glycyl-L-proline-4-methoxy- β-naphthylamide hydrochloride (r = 0.69). There were significant differences in the levels of these three enzymatic activities between sites exhibiting various degrees of clinical severity of gingival inflammation and harboring various proportions of B. gingivalis. The data from this study indicate that measurement of specific enzymatic activities in subgingival samples can be useful in the diagnosis of B. gingivalis-associated periodontitis.
Delayed Crack Development in Porcelain Due to Incompatibility Stress
Authors: Anusavice K.J. , Dehoff P.H. , Gray A. , Lee R.B. 
Published: November 2010

Delayed failure of metal-ceramic restorations due to static fatigue can occur when residual tensile stress is present in porcelain, even in the absence of intra-oral forces. Fixed-partial-denture (FPD) specimens and semicircular arch specimens with gapped cross-arch segments were employed to characterize the potential of two incompatible metal-ceramic systems for producing delayed crack development and to determine the relative sensitivity of these test designs as monitors of incompatibility stresses which resulted from thermal contraction differences between a nickel-chromium alloy and three experimental porcelains. The arch specimens were judged to be more suitable for analysis of residual stresses because of the larger magnitude of gap changes at each procedural change. However, the FPD specimens exhibited earlier evidence of delayed crack growth in porcelain when the thermal contraction coefficient of the metal exceeded that of the porcelain by either 1.7 × 10-6/°C or 2.2 × 10-6/°C. For these two states of incompatibility, the agreement between experimental gap values for the arch specimens and the gap values predicted from composite strip equations was excellent.
Microbiology of Root Surface Caries in Humans
Authors: Bowden G.H.W. 
Published: November 2010

Studies on the microbiology of root surface caries between 1970 and 1975 placed emphasis on Gram-positive pleomorphic filamentous rods, particularly Actinomyces viscosus and Actinomyces naeslundii. Both of these species had been shown to produce root surface caries in experimental animals. Since this time, studies have placed more emphasis on Streptococcus mutans, and S. mutans and Lactobacillus are significant in prediction of root surface caries risk in patients. Subsequent studies confirmed an association between S. mutans and 'soft' or 'initial' root lesions. Thus, it is important when determining the microflora of root surface lesions to make careful characterization of the state of the lesion. A second important aspect of the analysis of bacterial communities associated with root surface caries is better definition of the organisms. Most studies have concentrated on 'target organisms' S . mutans, S. sanguis, A. viscosus, A. naeslundii, Lactobacillus, and Veillonella. However, it has been known for 17 years that the Actinomyces associated with the lesions may be variants of A. viscosus and A. naeslundii. Such strains (intermediate strains) have been described in taxonomic studies of Actinomyces, yet little is known of the differences in physiology of these strains or their relationship to root surface caries. A similar situation exists with oral Streptococcus where new taxonomic divisions are being proposed. Recognition of the potential diversity within the 'target' genera of root surface caries could yield valuable data. Recent studies suggest that this is so, since samples from root surface lesions which contain S. mutans and Lactobacillus show a high isolation of S . mitis 1 and no isolations of A. naeslundii. Careful definition of the lesions of root surface caries and the flora will allow analysis to relate a specific bacterial community to the state of the lesion and assist in monitoring the control of the lesion through fluoride and antibacterials.
Compensatory Hyperplasia of the Rat Submandibular Gland Following Unilateral Extirpation
Authors: Schwartz-Arad D. , Michaelp Y. , Zajicek G. 
Published: November 2010

This study investigated the morphological changes in rat submandibular glands undergoing compensatory hyperplasia. Fifteen adult male rats underwent left submandibulectomy, after which they were killed in groups of five (at days 3,7, and 14), and their right submandibular glands (SMG) were excised. Fifteen control rats were killed in groups of five (at days 0, 7, and 14), and their right SMG were removed. Sections of 3 μm were cut, and the parenchymal and stromal cells were counted in 50 microscopic fields and sorted according to their morphological features and "class". Class is equivalent to the number of nuclei in an acinar or tubular cross-section. No change in glandular weight was noted post-surgery. Total cell count/field rose to 138.5 ± 7.1% of control values on day 3 after gland extirpation, remaining almost constant thereafter until the end of the experiment. Acinar cell count and class showed a 154.1% peak on day 3, followed by a 30% drop in cell count by day 7 and an equivalent decline in class by day 14. Tubular cell count increased gradually to 146.5% by day 14, without a change in class. In the first week, the increase in tubular cells was mainly due to intercalated duct (ID) cells, while in the second week, there was a sharp rise in granular duct (GD) cells. This diverging cellular behavior indicates that the GD cell stems from the ID cell. The cellular changes in the hyperplastic SMG indicate death of newly generated acinar cells and expansion of the glandular progenitor compartment, as expressed in elongation of the ID.
A Study of the Ability of an in situ Remineralization Model to Differentiate between the Effects of Two Fluoride Dentifrices that Produced Significantly Different Clinical Caries Results
Authors: Mellberg J.R. , Petrou I.D. , Grote N.E. 
Published: November 2010

The purpose of this study was to determine whether an in situ remineralization model was able to show a difference in the effects of two dentifrices of different fluoride concentrations and significantly different clinical efficacies. Three dentifrices were tested in a double-blind, cross-over study design. The products contained 0 ppm F, 250 ppm F, or 1000 ppm F from sodium fluoride and were formulated with a silica base according to the formulations used in a human caries trial (Koch et al., 1990). Nineteen subjects each carried three or four thin sections of enamel in their partial dentures. The thin sections, containing artificial caries lesions, were covered with a steel mesh to provide space for plaque formation and then brushed in situ three times daily with the dentifrices. Following the two-week treatment periods, the specimens were removed from the dentures and analyzed for changes in mineral content. The findings showed that the placebo dentifrice (0 ppm F) resulted in 56.8 ± 74.3% demineralization, the 250-ppm-F dentifrice produced 12.9±41.3% demineralization, thereby showing partial caries protection, and the 1000-ppm-F dentifrice produced 17.3 ±32.1% remineralization. Linear regression analysis showed that the percent remineralization was significantly related to the fluoride concentration in the dentifrice (p < 0.001). The 250-ppm-F dentifrice was also significantly less effective than the 1000-ppm-F dentifrice (p = 0.04, one-tailed Fisher Protected LSD test). These findings are in accord with the human caries trial and support the use of the present in situ remineralization model for prediction of the anticaries efficacy of fluoride dentifrice products.
Synthesis and Evaluation of New Oxaspiro Monomers for Double Ring-opening Polymerization
Authors: Stansbury J.W. 
Published: November 2010

Polymerization with expansion in volume can be achieved with spiro orthocarbonate monomers through a double ring-opening process wherein two bonds are cleaved for each new bond formed. The resulting expansion can be applied to counter the polymerization shrinkage associated with the conventional methacrylate monomers used in dental composites and thereby provide formulations with drastically reduced degrees of shrinkage. New monomers have been prepared that exhibit enhanced reactivities and ring-opening efficiencies compared with earlier free-radical-polymerizable oxaspiro compounds. In dental composite formulations, the monofunctional oxaspiro monomers provided DTS values equivalent to those of the controls under certain curing conditions; however, only modest reductions in polymerization shrinkage were observed. 2,3-Bis(methylene) spiro orthocarbonate monomers with a conjugated diene structure were also synthesized and evaluated. These novel monomers appear to offer significant potential for future development of free-radical ring-opening polymerization. While visible-light-cured formulations of the bis(methylene) compounds with methacrylate comonomers did not yield acceptable composite materials in this initial attempt, the high reactivity and the ability to form rigid, cross-linked polymers make this type of monomer worthy of continued investigation. These properties may allow the bis(methylene) oxaspiro monomers to be used alone or in concert with other ring-opening monomers for special applications.
Comparison of Rates of Enamel Synthesis in Impeded and Unimpeded Rat Incisors
Authors: Skobe Z. , Heeley J.D. , Dobeck J.M. , Prostak K.S. , Maravelis L. , Stern D.N. 
Published: November 2010

Periodic intubations of rats with solutions of fluoride (F) lead to the appearance of bands of disrupted pigmentation in continuously erupting incisors. Distances between fluorotic bands reflect time intervals between intubations. In this experiment, the periodicity of fluorotic banding was used for estimation of the rate of enamel synthesis in impeded and unimpeded rat incisors. Rats kept on a low-F diet and distilled water were intubated two or four times per week with 2 mg NaF/150 g body weight. In a group of rats, one of the mandibular incisors was cut at the gingival margin after two weeks, and intubations were continued for an additional two weeks. In another group of F-intubated rats, incisors were cut or notched at the gingival margin twice, six days apart. Control rats either received the same periodic F intubations or were maintained on the low-F diet without intubation. Measurements of spacing between fluorotic bands were identical in impeded and unimpeded teeth, even though the latter erupted at a faster rate. In unimpeded mandibular incisors, there was a significant elongation of the secretory zone and a shortening of the pigmentation zone, resulting in reduced pigmentation intensity of the erupted portions of the teeth. The results show that the rate of enamel synthesis is independent of the eruption rate.
Analysis of progression-free survival data using a discrete time survival model that incorporates measurements with and without diagnostic error
Authors: Hunsberger Sally , Albert Paul S , Dodd Lori 
Published: November 2010

Background In cancer studies progression-free survival (PFS) is becoming a very important endpoint in the development of new therapeutic agents. Two methods of determining progression are typically used: (1) the local radiologist evaluates scans and (2) scans are reviewed by an independent blinded (central) reviewer. The second method is considered to be the reference standard but is expensive, time consuming, and logistically difficult. The first method has measurement error associated with it, but, it is less expensive and easier to obtain. Purpose This article explores a new method for analyzing PFS data. Methods When PFS data using the test with measurement error are analyzed, inferences about covariate effects may be invalid due to bias. A sampling strategy is evaluated where data are collected on a subset of subjects using the reference test and on all subjects using the test that has error. The strategy is designed to maintain valid inferences while requiring the more expensive or difficult test on a small proportion of patients. In the analysis of the data we incorporate subject-specific and time-dependent covariates into the diagnostic errors (sensitivity and specificity) of the tests. We also propose a modeling formulation that accounts for unobserved covariate affects on diagnostic error through a shared random effect. We explore the effect of different diagnostic test properties on inference via simulation and use the methodology to analyze a renal cancer example. Results The simulations show inference is correct when a subset of measurements without error are collected. Limitations When the sensitivity and specificity of the local review is low a large fraction of centrally reviewed tests are needed to have high efficiency. Conclusions When designing a study where PFS is the primary endpoint collecting centrally reviewed data on a subset of patients may provide a valid an more feasible approach than collecting centrally reviewed data on all patients. Clinical Trials 2010; 7: 634—642. http://ctj.sagepub.com