bluuebunny/crossref_metadata_2025 huggingface dataset:
Bacterial Involvement in Denture-induced Stomatitis
Authors: Koopmans A.S.F. , Kippuw N. , de Graaff J.
Published: November 2010

Denture and mucosal plaque samples were collected from eight full-denture wearers of whom four suffered from denture-induced stomatitis (DIS). Cultures were made, and a proportional identification to species level was carried out of bacteria and yeasts. An inventory was made of the predominant flora. Results showed that the predominant microflora of both groups, both on dentures and the denture-bearing mucosa, consisted mainly of Gram-positive bacteria. Differences in the proportions of cocci were found between the predominant bacterial flora on the dentures. In the control group, 69% of the denture flora consisted of cocci, while on the dentures of the DIS group a mean of 33% cocci was found. Neither group of palates revealed any differences in the proportions of cocci. On these locations a mean of 69% was found. The plaque of dentures and the palates of the healthy group showed means of 35% and 31%, respectively, of obligate anaerobic bacteria, while in the DIS group these percentages were 56% and 43%, respectively. No obligately aerobic bacteria were found. Candida species was detected in both groups, both on dentures and palates in very low numbers (DIS group, median palates 0.02%, median dentures 0.25%). The predominant organisms were Streptococcus species, of which S. salivarius was mostly present on the palates of both groups. Other species which were regularly found at different locations were Veillonella parvula and species of Lactobacillus, Bacteroides, and Actinomyces.
Effect of the Porosity of the Filler Aggregates on the Setting Expansion of Investment Material
Authors: Takahashi J. , Okazaki M. , Kimura H. , Haeuchi Y. , Kubo F.
Published: November 2010

Twenty experimental phosphate-bonded investments were prepared by the mixing of two types of fillers (spherical glass beads and irregularly shaped silica particles) with five types of filler aggregates of different porosities, and two different ratios of MgO to NH 4H2PO4. These investments were mixed with three different liquids, and their setting expansion, time until setting expansion began (induction time), and fluidity were measured under constant experimental conditions. The following results were obtained: (1) The setting expansion was significantly related to bulk porosity of filler aggregates, not to packed porosity, despite variations in type of filler, ratio of MgO to NH4H 2PO4 or type of liquid; and (2) the fluidity and the time until setting expansion began were also related to the bulk porosity of the filler aggregates.
The Release of Residual Monomeric Methyl Methacrylate from Acrylic Appliances in the Human Mouth: An Assay for Monomer in Saliva
Authors: Baker S. , Brooks S.C. , Walker D.M.
Published: November 2010

A gas-liquid chromatography assay has been developed for the estimation of methyl methacrylate monomer (MMA) in whole saliva, with a lower limit of detection in the order of 1μg/mL. Healthy human dentate subjects wore recently made autopolymerized or heat-polymerized polymethyl methacrylate (PMMA) palatal appliances. MMA released into saliva was detected for up to one week after insertion of autopolymerized appliances, with a maximum concentration of 45 μg/mL in whole saliva or 180 μg/mL in the salivary film on the fitting surface. The MMA was not detected in blood or urine. MMA was also present in the saliva of volunteers wearing appliances which had been heat-polymerized at 70°C for one hr but not cured at 70°C for three hr. The maximum amount of monomer released by an autopolymerized base plate was 29.5 μg in the first hour, which, while not a toxic or primary irritant dose, could possibly sensitize patients or elicit an allergic reaction. For minimization of monomer release, autopolymerized appliances should be immersed for 24 hr in water before being worn.
Mechanism of Improved Corrosion Resistance of Zn-containing Dental Amalgams
Authors: Sarkar N.K. , Park J.-R.
Published: November 2010

The aim of this study was to determine the mechanism of improved corrosion resistance of Zn-containing dental amalgams. Two Zn-containing conventional amalgams, their Zn-free counterparts, and three experimental amalgams (SnHg, ZnHg, and SnZnHg) were evaluated by the potentiodynamic polarization technique in 1% NaCl solution. The main difference between the two types of amalgams was found in their respective breakdown potentials at which passivity was destroyed. The breakdown potential of Zn-containing amalgams was about 200 mV more positive than that of the Zn-free amalgams. The improved stability of the Zn-containing amalgams has been attributed to the formation of a previously reported Zn stannate passive film which, according to the polarization data, is more resistant to the aggressive chloride ion than tin hydroxide that forms on Zn-free amalgams. The formation of Zn stannate was not found to affect the oxygen reduction reaction, the major cathodic reaction involved in the corrosion of dental amalgams.
Effects of Distance from the Pulp and Thickness on the Hydraulic Conductance of Human Radicular Dentin
Authors: Fogel H.M. , Marshall F.J. , Pashley D.H.
Published: November 2010

The purposes of this study were: (1) to measure the effect of distance from the pulp on the hydraulic conductance of human radicular dentin ; (2) to determine the influence of dentin thickness on the rates of fluid flow; and (3) to attempt to correlate dentinal tubule densities and diameters with root dentin hydraulic conductance. Dentin slabs prepared from extracted, unerupted, human third molar teeth were placed in a split-chamber device to permit quantitation of fluid filtration rate (hydraulic conductance). In the SEM portion of the study, dentinal tubule numbers and diameters were recorded. The results indicated that radicular dentin hydraulic conductance decreased with distance from the pulp and with increasing dentin thickness. Tubule density and diameter correlated well with the measured hydraulic conductances. The relatively low hydraulic conductance of outer root dentin makes it a significant barrier to fluid movement across root structure.
Changes of Secretory Ameloblasts in Mini-pig Fetuses Exposed to Ethanol in vivo
Authors: Matthiessen M.E. , Rømert P.
Published: November 2010

After addition of ethanol to the ordinary fodder of pregnant mini-pigs, ultrastructural changes were found in secretory ameloblasts from tooth germs of their mid-term fetuses. Compared with controls, many mitochondria showed abnormal shape and size, and some exhibited deposition of paracrystalline material in the matrix. An abnormal deposition of stippled material intercellularly was also observed. These changes were interpreted as signs of an abnormal secretory function.
The Effects of Sugars Intake and Frequency of Ingestion on Dental Caries Increment in a Three-year Longitudinal Study
Authors: Burt B.A. , Eklund S.A. , Morgan K.J. , Larkin F.E. , Guire K.E. , Brown L.O. , Weintraub J.A.
Published: November 2010

A three-year longitudinal study was carried out with a group of children, initially aged 11-15, residing in non-fluoridated rural communities in south-central Michigan. This report analyzes the relation between caries increment and consumption of sugars from all sources to see if accepted relationships have changed with the caries decline in the United States. There were 499 children who provided three or more 24-hour dietary recall interviews, and who received dental examinations at baseline and after three years.

Caries increment averaged 2.91 DMFS over the three years, with 81 % of new lesions on pit-and-fissure surfaces. Consumption of sugars from all sources averaged 156 g per day for males and 127 g per day for females, an average of 52 kg per person per year. Sugars constituted one-quarter of total caloric intake for both boys and girls, and the average number of eating occasions per day was 4.3.

Children who consumed a higher proportion of their total energy intake as sugars had a higher increment of approximal caries, though there was little relation to pit-and-fissure caries. The average number of daily eating occasions was not related to caries increment, nor was the average number of sugary snacks (defined as foods with 15% or more of sugars) consumed between meals, but the average consumption of between-meal sugars was related to the approximal caries increment. When children were categorized by high caries increment compared with no caries increment, a tendency toward more frequent snacks was seen in the high-caries children.

In an age of generally declining caries, it was concluded that higher average daily consumption of sugars, and higher between-meal consumption of sugars, was still a risk factor for children susceptible to approximal caries. Overall frequency of eating and frequency of ingestion of sugary foods between meals, however, were both poorly related to approximal caries increment. Pit-and-fissure caries could not be related to any aspect of sugars consumption.
Fourier Transform Infrared Spectroscopic Study of the Role of Tartaric Acid in Glass-ionomer Dental Cements
Authors: Nicholson J.W. , Brookman P.J. , Lacy O.M. , Wilson A.D.
Published: November 2010

(+) - Tartaric acid is incorporated into glass-ionomer dental cements to control the setting characteristics. FTIR has been used to examine the cements as they set, and has confirmed previous results that (+)-tartaric acid reacts more readily with the glass than does poly(acrylic acid), thereby delaying the setting of the cement. Subsequently, ions released by the glass become available for reaction with the polyacid, and gelation occurs. (+)-Tartaric acid not only reacts rapidly to yield calcium tartrate, but also enhances the rate at which aluminum polyacrylate is formed within the cement. Mesotartaric acid, by contrast, while rapidly forming calcium tartrate, does not enhance the rate of aluminum polyacrylate formation. As a result, this latter isomer merely suppresses the setting process; unlike (+)-tartaric acid, it does not also sharpen the set.
Utilization of a Continuous Streptococcal Surface to Measure Interbacterial Adherence in vitro and in vivo
Authors: Liljemarki W.F. , Bloomquist C.G. , Coulter M.C. , Fenner L.J. , Skopek R.J. , Schachtele C.F.
Published: November 2010

Cell-to-cell interactions are essential for the formation of dental plaque. A continuous layer of Streptococcus sanguis SA-1 cells fixed to a solid surface has been used to evaluate interactions among this bacterium, Haemophilus parainfluenzae, and Streptococcus sobrinus. S. sanguis cells were attached to a Falcon 3001 tissue culture plates or bovine enamel chips, coated with a biological adhesive. Scanning electron microscopy of the chips showed the streptococci as a contiguous surface. Radiolabeled bacteria were used to measure a second-species interbacterial adherence to the streptococcal-coated culture plates. Strains of H. parainfluenzae known to coaggregate (strain HP-28) and not to coaggregate (strains HP-42 and HP-80), in suspension with S. sanguis strain SA-1, were studied for adherence. Ten-fold-higher numbers of coaggregating strain HP-28 adhered in vitro to the streptococcal layer than did the non-coaggregating strains. S. sobrinus strain 6715 did not show appreciable adherence to the S. sanguis surface. Saliva did not affect the adherence of coaggregating or non-coaggregating H. parainfluenzae strains to S. sanguis strain SA-1. Bovine enamel chips, coated with streptococci, mounted on modified orthodontic appliances and placed in the mouths of three volunteers, facilitated the measurement of interbacterial adherence in vivo of streptomycin-resistant strains of H. parainfluenzae (HP-28R or HP-42R). Suspensions of bacteria were placed into the mouth, distributed throughout, and expectorated. After 15 or 120 minutes, the appliance with the chips was removed, the chips sonified, and colony-forming units (CFU) of streptomycin-resistant haemophili determined per chip. Similar to the in vitro experiments, ten times as many coaggregating HP-28R than non-coaggregating HP-42R adhered in vivo to the S. sanguis SA-1 layer in two of the three subjects. The measurement per mm2 in vitro and in vivo of cell-to-cell interactions facilitates accurate comparisons between the different strains and species and will facilitate studies on the interbacterial interactions involved in plaque formation.
Effect of Zeta Potential and Surface Energy on Bacterial Adhesion to Uncoated and Saliva-coated Human Enamel and Dentin
Authors: Weerkamp A.H. , Uyen H.M. , Busscher H.J.
Published: November 2010

Physicochemical surface characteristics of early plaque-forming bacteria and of human tooth surfaces were measured to establish their role in bacterial adhesion to intact dental tissue slabs. In addition, the influence of an experimental salivary pellicle was evaluated. Strains of S. mutans, S. sanguis, S. salivarius, A. viscosus, and A. odontolyticus showed relatively high surface free energies (range, 99-128 mJ.m-2) and carried a negative surface charge, at both physiological (μ = 0.057) and low (μ = 0.020) ionic strengths of the medium. Very large differences in hydrophobicity were detected when the hexadecane adsorption test was used for measurement. Powdered enamel and dentin were also negatively charged at low ionic strength but were slightly positively charged in the physiological buffer. The surface free energy of enamel and dentin increased upon saliva coating, whereas the surface charge was always negative.

The adhesion experiments showed: (1) large differences in the binding of various bacteria to the same surface; (2) an up to 20-fold difference in the binding of the same bacterium to different surfaces, although the binding of some strains was relatively independent of the type of surface or presence of a salivary pellicle; (3) a significant decrease in adhesion when the ionic strength of the medium was lowered, due to increased electrostatic repulsion (however, the adhesion of some bacteria was independent of the ionic strength of the medium); (4) different time-dependent adherence kinetics, depending on both the bacteria and nature of the solid surface; and (5) a propensity for plaque streptococci to bind to uncoated dentin.
Periodontal Disease in Adolescents: Some Clinical and Microbiologic Correlates of Attachment Loss
Authors: Carlos J.P. , Wolfe M.D. , Zambon J.J. , Kingman A.
Published: November 2010

The influence of several clinical and microbiological variables on the site-specific risk of attachment loss was studied in Navajo Indian adolescents aged 14-19. Diagnoses were made at mesio-buccal sites of the four first permanent molars. Case-control analytical methods were used, with A. actinomycetemcomitans, B. gingivalis, and B. intermedius considered the "risk" variables, and with calculus, gingival bleeding, age, and gender treated as possible confounders.

The presence of B. intermedius significantly increased the likelihood that attachment loss would be diagnosed at a site (odds ratio = 2.86). However, this association was confounded by calculus and gingival bleeding; when either or both were present, the effect of B. intermedius was markedly weaker.

Step-wise multiple logistic regression analyses showed that, of the variables considered, the combination of calculus, gingival bleeding, and B. intermedius gave the most parsimonious explanation of the presence of attachment loss. The chance that attachment loss would be diagnosed was increased five times when calculus was present, 16.5 times in the presence of both calculus and gingival bleeding, and 37 times when these variables plus B. intermedius were observed at a particular site.
Cusp Height Relationships between the Upper and Lower Molars in Japanese Subjects
Authors: Sekikawa M. , Kanazawa E. , Ozaki T.
Published: November 2010

Relationships of cusp height between the upper and lower first molars and between the deciduous second molars in Japanese subjects were analyzed with the aid of moiré contourography. In permanent molars, the height of the hypoconid had a mean value similar to that of the upper trigonal cusps, indicating that upper and lower functional cusps of the same height occlude with each other. In deciduous second molars, however, hypoconid heights were significantly smaller than trigonal cusp heights. Such differences in cusp height between permanent and deciduous dentition may be related to the function and phylogeny of tooth or jaw movements.
Antibiotic Resistance and Production of Inhibitory Substances among Bacterial Strains Isolated from the Oral Cavities of BALB/c Mice
Authors: St-Amand L. , Lavoie M.C.
Published: November 2010

In the oral cavities of BALB/c mice, microbial population levels are regulated by multifactorial processes. Factors include the production of inhibitory substances and the exchange of genetic material. In this work, 371 isolates from different sites (saliva, tongue, teeth, and mucosa) of the oral cavities of BALB/c mice were screened for resistance to antibiotics and antimicrobial activity. Antibiotic-resistant strains represented 25% of the total flora. Among the predominant species, all the S. faecalis isolates showed multiresistance, and 23% of the Lactobacillus murinus isolates and 15% of the Staphylococcus aurcus were resistant to at least one antibiotic. Resistance to aminoglycosides (neomycin, streptomycin, kanamycin, and gentamicin) was most frequently encountered. In S. faecalis, high levels of resistance were recorded to neomycin and streptomycin but not to gentamicin or kanamycin. Macrolides (M), lincosamides (L), streptogramin B (S), tetracycline (Tc), and chloramphenicol (Cm) resistance was also present in multiresistance patterns, especially among S . faecalis isolates. Hemolytic (Hly+) streptococci were less resistant to MLS, Tc, and Cm than were non-hemolytic (Hly-) isolates. Resistance to β-lactam antibiotics was detected only among staphylococci and with a low prevalence (4%). The frequencies of strains producing antimicrobial substances against the indicator strains (S. mutans LG-1, S . sanguis Ny 101, and A . viscosus Ny 1) were high for L. murinus (76%) and S. faecalis (57% for Hly- and 90% for Hly+), but low for S. aurcus (7%). These results indicate that the indigenous oral flora could interfere with colonization by allochthonous micro-organisms and that resistance patterns should be taken into account for the elimination of the oral indigenous flora by antibiotic treatment. The indigenous oral flora could thus interfere with dental caries assays in mice.
Electron Probe Micro-analysis for Subsurface Demineralization and Remineralization of Dental Enamel
Authors: Chu J.S. , Fox J.L. , Higuchi W.I. , Nash W.P.
Published: November 2010

A quantitative study of fluoride distribution profile changes in dental enamel was conducted by means of electron probe micro-analysis (EPMA). Fluoride-deposited hydraxyapatite powders were chosen as fluoride standards, and analytical conditions were optimized. The lower limit of detection for fluoride was estimated to be 270 ppm, with an accelerating voltage of 5 kV, a specimen current of 40 nA, and a counting time of 40 seconds. Fluoride profiles in fluoride-treated dental enamel, which exhibited intact surface layers and subsurface demineralization, were determined. The results were also compared with those of an acid-abrasion method, and reasonable consistency was found between these two methods, although the acid-abrasion procedure yielded a slightly lower fluoride content in the initial layers, followed by a higher content of fluoride in the deeper layers. The precision of fluoride profile data obtained from EPMA permits further studies to be conducted on the kinetics of subsurface demineralization and intact surface layer formation ("white spot" formation) which is observed during the acid challenge of dental enamel.
5-Hydroxytryptamine Modulation of Rat Parotid Salivary Gland Secretion
Authors: Chernick W. , Bobyock E. , Bradford P.
Published: November 2010

5-Hydroxytryptamine (5-HT) has been reported to produce significant responses in blowfly salivary glands, but little information is available concerning its action on mammalian salivary glands. When 5-HT (0.1 μmol/L to 10 μmol/L) is infused i. a. into anesthetized rats, no salivary secretion is obtained from either parotid or submandibular glands. However, when 5-HT is infused along with a threshold concentration of acetylcholine (0-1 mmol/L), potentiation of parotid secretory response is seen with 5-HT (1 μmol/L, 260% increase; 10 μmol/L, 146% increase). Substance P (0.3 μmol/L) combined with 5-HT (1 μmol/L) also resulted in a potentiation of parotid secretion (160% increase). Protein and calcium concentrations were not altered during such treatments. No potentiation of submandibular secretion was noted. Experiments in vitro with parotid cell aggregates exhibited no potentiation associated with the combined use of 5-HT and carbachol, as measured by amylase secretion and inositol trisphosphate accumulation. The experiments indicate that 5-HT substantially modulates parotid salivary secretion in vivo; however, the in vitro findings suggest that 5-HT does not act directly on surface glandular receptors. The magnitude of the in vivo potentiation could very well implicate circulating or released 5-HT as a physiological modulator of endogenous neurotransmitter action.
Influence of Milk and Food on Fluoride Bioavailability from NaF and Na2FPO 3 in Man
Authors: Trautner K. , Einwag J.
Published: November 2010

Aqueous solutions of NaF and sodium monofluorophosphate (MFP) were given to fasting young adults in an intra-individual cross-over study. Plasma fluoride (F) levels were measured by use of a F-ion-sensitive electrode, and eight-hour profiles of F concentrations in plasma were determined. F availability and pharmacokinetic data were identical for both substances. Furthermore, the same subjects were given tablets containing 2 mg F, either as NaF or as MFP, under different experimental regimens: (a) on a fasting stomach, (b) together with milk, or (c) together with breakfast and milk. Equal F availabilities were observed for both substances. Plasma peak levels were reduced when the tablets were taken together with food. Intake of milk reduced F availability by 30% compared with the fasting stomach experiment; this effect was abolished when milk was taken as part of the breakfast. It is suggested that formation of Ca salts and entrapment of F in coagulation products of milk are important factors causing reduction of F availability, and that prolonged stay of the chyme after concomitant ingestion of food allows F to become liberated from bound forms and coagulation products by digestion processes.
Microstructural Features of Carious Human Enamel Imaged with Back-scattered Electrons
Authors: Pearce E.I.F. , Nelson D.G.A.
Published: November 2010

We have used back-scattered electrons (BE) in the scanning electron microscope to produce mineral density images of enamel. Flat surfaces of artificially-carious enamel, softened in an intra-oral experiment, and naturally-carious (white spot) enamel were polished to a high gloss with diamond lapping compound, rendering them almost featureless by secondary electron scanning electron microscopy. They were then examined at 10 to 30 kV in a Philips 505 instrument fitted with a 4-quadrant BE detector. Study of surfaces prepared approximately parallel to the natural surface showed that mineral was lost from both prism core and the interprismatic region, leaving a thin mineral-rich rim at the prism periphery. The same lesions viewed longitudinally on a surface prepared perpendicular to the natural surface showed mineral-rich bands at the prism margins in the outer enamel. Near the advancing front of the lesion, the prism junctions were widened and the prism cores sometimes hypermineralized. Natural lesions sectioned in the prism long axis showed features previously seen with other techniques, e.g., cross-striations and striae of Retzius, but in much greater detail. Mineral enrichment at the prism periphery in the lesion body and a widening of the prism junction at the advancing fronts of lesions in permanent teeth were most obvious. Calculations showed that with an accelerating voltage of 30 kV, the images reflected mineral density up to 4 μm beneath the surface. BE microscopy produces a high-resolution image of mineral loss or gain in carious enamel, with relatively easy sample preparation.
Fluoride in Plaque Following Use of Dentifrices Containing Sodium Monofluorophosphate
Authors: Duckworth R.M. , Morgan S.N. , Burchell C.K.
Published: November 2010

Previous work showed that plaque fluoride increased with increasing NaF content of mouthwashes following daily use. The main aim of this study was to test whether a similar relationship was detectable after regular use of dentifrices containing amounts of sodium monofluorophosphate equivalent to 1000, 1500, and 2500 μg F/g. Plaque was collected from three groups, each consisting of approximately 80 children, who had each used one of the dentifrices for one year. Plaque fluoride increased significantly with increasing Na2FPO3 content of the dentifrices. For the 1000-μg-F/g group, plaque fluoride also increased significantly with increasing frequency of dentifrice use, but did not correlate with amount of dentifrice applied per brushing. The inverse correlation observed between mean plaque fluoride concentrations and mean three-year caries increments suggests that oral fluoride measurements may prove valuable in estimating the likely anti-caries efficacy of fluoride-containing dental products.
Tempering Stresses in Feldspathic Porcelain
Authors: Dehoff P.H. , Anusavice K.J.
Published: November 2010

The objective of this study was to develop an analytical model to calculate transient and residual (tempering) stresses in dental porcelain plates subjected to cooling rates used by commercial laboratories. The model incorporates linear viscoelasticity and structural relaxation effects.

The viscosities of three experimental body porcelains and three experimental opaque porcelains as a function of temperature were calculated from creep rates measured in a bending beam viscometer. Measurements were made under thermal equilibrium conditions for temperatures ranging from 550°C to 625°C. Thermal expansion data measured in a differential dilatometer at slow heating rates were supplied by the manufacturer. Temperature distribution in the plates as a function of convective heat transfer coefficient, initial plate temperature, and plate thickness was calculated by use of standard numerical techniques.

Calculations of transient and residual stress were performed for one body porcelain, for two plate thicknesses, and for three variable cooling rates. Calculated surface residual stresses were strongly dependent on plate thickness, cooling rate, and initial soak temperature. For the cases studied, the maximum residual surface compressive stress was 26.4 MPa.
The Detection of Incipient Caries with Tracer Dyes
Authors: O'Brien W.J. , Vazquez L. , Johnston W.M.
Published: November 2010

The purpose of this study was to determine the increase in color contrast produced by the use of a tracer dye in detection of incipient caries lesions with transillumination.

Twenty four caries-free first premolars were immersed in an acid gelatin for production of artificial incipient caries lesions. After the lesions had developed, these teeth were photographed by transillumination. Two photographs were taken of each tooth. The first photograph showed the lesion without dye. A blue tracer dye was then added and absorbed by the lesion, and a second photograph was taken. The data on the color difference were obtained by use of a reflectance colorimeter and showed a four-fold increase between the lesion and surrounding area with the dye. A two-way analysis of variance was used for the statistical interpretation. The color difference between the lesion without the dye and then with the dye was significant. The use of the blue tracer dye, therefore, significantly increased the contrast in the images of the artificial incipient lesions.
A Modified DDE Index for Use in Epidemiological Studies of Enamel Defects
Authors: Clarkson J. , O'Mullane D.
Published: November 2010

The aim of this study was to investigate possible modifications to the DDE Index to make it simpler to use and to make the data collected more meaningful and amenable to analyses and interpretation. After the use of the DDE Index in a National Study in Ireland, initial alterations to the Index were tested on a group of children with enamel defects, in Ireland and New Zealand. The DDE Index was then modified to allow for the measurement of demarcated, diffuse, and hypo-plastic defects and their severity. With the Modified Index, the prevalence of defects both on index teeth and all permanent tooth surfaces of 8-and 15-year-old children in fluoridated Cork City and non-fluoridated areas of Cork County and Manchester, U.K., was measured. The prevalence of enamel defects on one or more index teeth of children in the three areas ranged from 30 to 42% in 8-year-olds and from 31 to 38% in 15-year-olds. The percentage of children affected as seen by full-mouth examination was somewhat higher, ranging from 38 to 51 % for 8 year-olds and 58 to 63% for 15-year-olds. The percentage of index teeth affected (7 to 14%) was generally higher than for all teeth (5 to 9%). Demarcated opacities were the most common defect seen. Diffuse opacities were found to be the discriminating factor between the fluoridated and non-fluoridated areas. In all areas, the vast majority of diffuse opacities extended over less than 1/3 of the surface area of the teeth affected. As a result of this study, proposals for a single scoring DDE Index for use in general purpose and screening surveys are made. The modifications to the DDE Index allow for efficient recording of the prevalence and severity of enamel defects.
Curing Light-activated Composite Cement through Porcelain
Authors: Chan K.C. , Boyer D.B.
Published: November 2010

The purpose of the study was to determine the exposure times needed to harden a light-activated composite cement through various thicknesses of porcelain. A negative exponential model was developed with which the relative hardness of a composite could be predicted from the product of the exposure time and the square root of the light intensity at 470 nm. Hardness data obtained by varying the exposure time and porcelain thickness were found to fit this model. A relationship was derived to predict the required exposure time, t, of a composite under porcelain with a transmission coefficient, Tc, and a thickness, 1 : t = toT c-½, where to is the exposure time of the composite alone.
A Clinical, Radiographic, and Histological Evaluation of Permucosal Dental Implants of Dense Hydroxylapatite in Dogs
Authors: De Lange G.L. , De Putter C. , De Groot K. , Burger E.H.
Published: November 2010

A clinical, histological, and radiographic examination was performed on 77 permucosal dental implants, made of dense sintered hydroxylapatite: 34 solid cylinders and 43 hollow cylinders. The hollow cylinders were pre-compressed between two titanium caps. The implants were placed in partly edentulous mandibles of dogs, and were physiologically loaded. Healing was clinically and radiographically evaluated during a six-month to five-year period.

At various times, implants with their surrounding tissues were removed and prepared for light and electron microscopy. All implants showed a good initial fit and were maintained in place without undercut or mechanical stabilization. After 18 months, 76% of the solid cylinders had fractured at the implant/bone junction due to fatigue. However, the submerged portions of the solid cylinders were preserved without clinical problems, and became entirely embedded in bone. The pre-stressed implants did not fracture, and 91% were functioning 24 months after placement. The average scores of pocket depths and gingival bleeding showed no significant differences between implants and surrounding natural teeth.

Bone deposition occurred on the entire surface of the implant below the crest of the alveolar bone, and intimate bone contact was confirmed by electron microscopy. It was also observed that a layer of bone tissue was deposited on the implant surface in the permucosal area just above the alveolar bone level. Embedding of gingival fibers in this layer resulted in gingival attachment to the implant, comparable with that of natural teeth.
Prevalence of and Factors Associated with Root Decay in Older Adults in Canada
Authors: Locker D. , Slade G.D. , Leake J.L.
Published: November 2010

We collected data on the oral health status and treatment needs of a random sample of persons aged 50 years and over. Data on root decay were obtained from the 183 subjects who were dentate. All remaining teeth were examined for root decay and restorations, whether root surfaces were affected by recession or not. Analysis was undertaken by case and root surface, with separate analyses of decayed (DS), and decayed and filled (DFS) root surfaces. One or more root surfaces with untreated decay were found in 37.2% of subjects, while one or more decayed or filled root surfaces were found in 56.8%. The mean number of decayed sutfaces was 1.3 per person, and the mean number of decayed and filled root surfaces was 2.6. Multiple and logistic regression analyses showed that oral health variables were more important predictors of the presence and severity of root decay than demographic, general health, or dental care factors.
Dental Plaque and Caries on Occlusal Surfaces of First Permanent Molars in Relation to Stage of Eruption
Authors: Carvalho J.C. , Ekstrand K.R. , Thylstrup A.
Published: November 2010

The occlusal surfaces of partly and fully erupted first right permanent molars were examined with respect to the occurrence and distribution of plaque and dental caries in a group of 57 six- to eight-year-old children. The children were classified into four groups ranging from one tooth partially erupted to full occlusion. Occlusal plaque was recorded at two levels of examination: (1) visible plaque and (2) detailed mapping by means of a plaque detector system. Dental caries was recorded after professional cleaning. The recording of plaque was repeated after 48 hr without oral hygiene. The findings showed a significant reduction in the easily detectable plaque in fully erupted teeth, compared with the three groups representing partly erupted teeth. The detailed mapping of plaque showed a clear pattern of preferential locations related to the macromorphology of the occlusal surfaces, and revealed reduction in the frequency of thick plaque accumulation in the fully erupted teeth. The proportion of active lesions was reduced in fully erupted teeth, and arrested lesions were mainly observed in the same group. This indicated that erupting teeth are more likely to develop dental caries, due to favorable conditions for plaque accumulation. Functional usage of teeth in addition to improved access for toothbrushing promoted arrestment of lesions initiated during eruption.
Efficacy of Panoramic Radiography in Dental Diagnosis and Treatment Planning
Authors: Kantor M.L. , Slome B.A.
Published: November 2010

We compared treatment decisions based on a clinical examination alone with decisions based on an examination plus a panoramic radiograph to determine whether the panoramic radiograph increased the diagnostic yield and consequently affected treatment. Provisional treatment plans, based on a screening clinical examination alone (n = 33), or on a screening clinical examination plus panoramic radiograph (n = 43), were compared with final treatment plans based on a complete diagnostic assessment (including all necessary radiographs). For this analysis, the final treatment plan was considered correct and used as the gold standard. The two groups used in the comparison were equivalent in age, gender, and final treatment plan needs. The availability of a panoramic radiograph did not improve the accuracy with which provisional treatment plans predicted the number of teeth requiring composites, amalgams, crowns, or extraction, nor did it improve the accuracy of the assessment of the periodontal status (Wilcoxon rank sum, alpha = 0.05). The proportion of patients who had an intra-oral full-mouth series as part of the complete diagnostic work-up was essentially the same for both groups (58% and 60%, respectively); the availability of the panoramic film did not reduce the need for full-mouth series radiographs for the development of the final treatment plans.
A New Porcelain Repair System with a Silane Coupler, Ferric Chloride, and Adhesive Opaque Resin
Authors: Matsumura H. , Kawahara M. , Tanaka T. , Atsuta M.
Published: November 2010

A new porcelain repair system was developed which uses a two-liquid primer, self-cured opaque resin, and light-cured composite. The primer consisted of two liquids. One component was 4% 3-trimethoxysilylpropyl methacrylate in methyl methacrylate, and the other component was 0.5% ferric chloride in ethanol. A self-curing opaque resin, 4-META/MMA-TBB opaque resin, was used as an adhesive to bind the porcelain and the composite. Adhesive opaque resin was applied on the roughened and primed porcelain. Light-cured composite was placed over the 4-META opaque layer. A shear test was performed for investigation of the strength and durability of the bonding. The result was that for all specimens after 20,000 thermocycles, fracture or crack propagation during the shear test occurred in the porcelain, rather than in the bond. This system may be used to repair fractured porcelain facings without removal of prostheses.
T Helper and T Suppressor Cell Reversal During the Development of Induced Rat Periapical Lesions
Authors: Stashenko P. , Yu S.M.
Published: November 2010

T helper (TH) and T suppressor (TS) cells were enumerated in developing rat periapical lesions in order to identify the cell type associated with the active phase of lesion formation. Experimental pulp exposures were made in all molar teeth of 29 Sprague-Dawley rats, and teeth were left open to the oral environment. On days 15, 20, 30, and 90 after induction, inflammatory cells were isolated from periapical lesions, and T helper (W3/25+), T suppressor (OX8+), and total T cells (W3/13 +) were enumerated by reactivity with monoclonal antibodies. During the early, most active phase of lesion development (day 15), TH cells outnumbered TS cells (TH/TS = 1.7). However, by day 20, when lesion expansion had slowed, the TH/TS ratio was reversed (0.9) and remained so for up to 90 days after induction (TH/ TS = 0.7). Total T cell numbers did not change over the period of observation. TH cells thus predominated during the active phase of lesion development, whereas TS cells were associated with the chronic phase. This dynamic TH/TS reversal indicates that immune responses which occur within periapical lesions are highly regulated. In addition, the predominance of TH during the active phase of lesion development suggests that TH-mediated activities may be involved in the bone destruction and immune cell activation within periapical lesions.
Remineralization of Artificial Caries-like Lesions in Human Enamel in situ by Chewing Sorbitol Gum
Authors: Leach S.A. , Lee G.T.R. , Edgar W.M.
Published: November 2010

The objective of the study was to determine quantitatively the effect on the potential for in situ remineralization of artificial caries-like lesions in human enamel when sugar-free gum containing mainly sorbitol as sweetener was chewed after meals and snacks. Artificial white-spot lesions were created in extracted human premolars and divided into three parts. One part was used as reference and the other two worn consecutively for two 21-day periods by 10 volunteers in a cast silver band cemented on lower molar teeth and covered with gauze to promote plaque formation. During the experimental periods, the subjects used fluoridated toothpaste twice daily, and consumed three meals (breakfast, lunch, and dinner) and two snacky (selected from chocolate bar, raisins, chocolate wafer, and iced cupcake). Sorbitol gum was chewed for 20 min immediately after each meal or snack during one of the experimental periods. The three parts of the enamel lesions were then sectioned (≏80 μm) and examined together by means of quantitative microradiography and by polarized light microscopy. All estimates of mineral content indicated that significant remineralization occurred and was approximately doubled with gum-chewing. It is suggested that sorbitol gum stimulates salivation, which is responsible for the significantly enhanced remineralization, thus contributing to a therapeutic, curies-preventive effect. Because the gum was chewed immediately after meals and snacks, inhibition of demineralization may also have occurred.
Bovine Tooth-derived Bone Morphogenetic Protein
Authors: Kawai T. , Urist M.R.
Published: November 2010

Eight groups of dental tissues were mechanically dissected from the mandibles of one-year-old steers; they were then defatted and decalcified in HCI. The noncollagenous proteins were extracted with various solvents from collections of tissue and bio-assayed for osteo-inductive activity. Collectively, the hard tissue (dentin, enamel, and cementum) noncollagenous proteins were fractionated by molecular sieve chromatography, hydroxyapatite affinity chromatography, and ion exchange chromatography. Osteo-inductive activity of each protein fraction was determined by implantation in the quadriceps muscle pouch of mice. The quantity of bone was measured by computerized image analysis. From 71% to 83% of 41 implants of dental hard tissues induced bone formation. The quantity of bone was greater from unerupted than from erupted teeth. Dental soft tissues that had no osteo-inductive activity were rich in a 14-kDa protein, presumably matrix gamma-carboxyglutamic acid-rich proteins. Proteins with Mr of from 15 to 28 kDa were associated with osteo-inductive activity. Components with Mr greater than 28 kDa had no activity. These observations suggest that bovine teeth have a selection of osteo-inductive proteins that is comparable in range of MW to bovine bone morphogenetic protein.
Resolution of Ion Translocating Proteolipid Subclasses Active in Bacterial Calcification
Authors: Swain L.D. , Renthal R.D. , Boyan B.D.
Published: November 2010

Formation of calcium hydroxyapatite occurs on membrane surfaces via interaction of calcium, inorganic phosphate, phospholipids, calcifiable proteolipids, and ion flux to and from the nucleating site. Recently, this laboratory reported that proteolipids from the calcifying bacterium, Bacterionema matruchotii, act as an ionophore when reconstituted into bacteriorhodopsin-proteoliposomes. This ionophoric activity is blocked by [14C] dicyclohexylcarbodiimide ([14C]DCCD). SDS-PAGE shows that [14C]DCCD binds to a single band of Mr 8500. To determine whether proteins other than the [14C]DCCD-binding protein are involved, we examined the function of proteolipid species extracted by solvents of differing polarity. Proteolipids were isolated independently from chloroform:methanol (2:1) and chloroform:methanol:HCl (200:100:1) extracts of the bacteria by Sephadex LH-20 chromatography and were electrophoresed on 12.5% acrylamide gels. The chloroform:methanol extract contained a major band at Mr 10,000 that was not present in gels of proteolipid isolated by acidified solvent. Proteolipids extracted in chloroform:methanol:HCl included a broad band at Mr 8500, which co-migrated with the [14C] DCCD-binding protein. The rate and extent of proton translocation were not altered when either proteolipid extract was added individually to bacteriorhodopsin proteoliposomes. However, when proteolipids isolated from the chloroform:methanol and chloroform:methanol:HCl extracts were combined, the rate and extent of translocation were increased. These data demonstrate that at least two proteolipid proteins are necessary for ionophoric activity, the Mr 10,000 protein isolated by chloroform:methanol 2:1 and the [14C]DCCD-binding protein requiring acidified solvent for extraction.
In vivo Effects of Zinc and Chlorhexidine on Dental Plaque Ureolysis and Glycolysis
Authors: Giertsen E. , Scheie A.Aa. , Rolla G.
Published: November 2010

We assessed the in vivo effects of zinc and chlorhexidine (CH) on plaque ureolysis and glycolysis in five volunteers. We monitored plaque pH by a surface glass electrode on two teeth in each subject, after topical application of either 5% wt/vol urea or 5% wtlvol glucose solutions. The recordings were repeated 15 and 75 min after a single mouthrinse, with either 20 mmol/L zinc acetate or 0.33 mmol/L CH diacetate.

Ureolytic activity decreased significantly (p<0.03) up to 75 min after a single mouthrinse with the zinc-containing test solution. CH had no effect on plaque ureolytic activity. Acid production by dental plaque decreased significantly (p < 0. 01) up to 75 min after a single mouthrinse with either the zinc- or the CH-containing test solution.
Tissue Distribution of RNAs for Cystatins, Histatins, Statherin, and Proline-rich Salivary Proteins in Humans and Macaques
Authors: Sabatini L.M. , Warner T.F. , Saitoh E. , Azen E.A.
Published: November 2010

The tissue distribution of the mRNAs for a number of salivary proteins [proline-rich proteins (PRPs), statherin, cystatins, and the histatins] has been examined in humans and macaques in order to investigate their possible functions and tissue-specific regulation. We have shown that PRP RNAs (0.8-1.5 kb) are expressed in human and rhesus parotid and submandibular glands, and in the human bronchus. The genes for the acidic and basic PRPs are differentially regulated in these tissues. RNAs for acidic PRPs are predominantly expressed in the submandibular gland, for basic PRPs in the respiratory tract, and for both acidic and basic PRPs in the parotid gland. Protein studies of secretions from these tissues confirm the RNA results. Statherin RNA (0.65 kb) was detected in human and rhesus parotid and submandibular glands and the human bronchus, as well as in rhesus lacrimal glands. Statherin was found by tissue immunoperoxidase staining in the serous cells of respiratory tract submucosal glands, which is the same location for the synthesis of PRPs. Several cystatin RNAs (0.8-1.3 kb) were differentially expressed in human parotid glands, submandibular glands, and the bronchus, and in lacrimal glands from both rhesus and cynomolgus macaques. RNAs (0.6 kb) for the histatins were found only in parotid and submandibular glands. Thus, it appears that PRPs, statherin, and cystatins may play a broader role in the physiology of biological fluids and secretions than previously suspected, since they are found in secretions other than saliva. However, the functions of the histatins are restricted to saliva. These studies also pose some interesting questions regarding the differential expression of these genes in a variety of secretory tissues.