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Surface characteristics that are considered important for bacterial attachment to thirteen orthodontic bonding composite cements and one glass ionomer cement were examined in vitro before and after toothbrush abrasion. The surface roughness and contact angle measurements were found to be statistically significantly different between the materials, both before and after brushing, and there were also statistically significant changes within materials after brushing. There were low correlation coefficients between surface roughness and contact angle for both pre-and post-brushed materials.

The release of fluoride from 1) discs made from five glass ionomer cements and two composites, and 2) the same discs after exposure to different NaF solutions, were studied. The specimens were placed in distilled water for 10 wk. After 24 h and then once a week, the specimens were transferred to fresh distilled water. After 5 wk, the specimens were divided into four groups and exposed to 0, 0.02, 0.2 and 2% NaF solutions for 5 min. The fluoride release was highest during the first week after preparation, after which it decreased sharply and then more slowly. The amount of fluoride released was ordered: liner/base>restorative glass ionomer>composites. The composites released significantly less fluoride than the glass ionomer cements. After exposure to NaF, the fluoride release was significantly higher for the silver cermet material than for the other glass ionomers tested. From a clinical point of view, the results from this study imply that glass ionomer restorations may act as intraoral devices for the controlled slow release of fluoride at sites at risk for recurrent caries.

Summary The purpose of this study was to compare the sealing ability of high-copper amalgam, glass ionomer cement, and silver glass ionomer cement as retrofitting materials when used with and without varnish. Seventy extracted human single-rooted anterior teeth were instrumented and the root canals obturated with laterally condensed gutta-percha and sealer. The apical 3 mm of each root was resected and a 2 mm-deep apical Class I preparation cut. The roots were then randomly allocated to six groups of 10 teeth and retrofitled with one of die experiment materials. Group I comprised high-copper amalgam; group 2, high-copper amalgam with cavity varnish; group 3, glass ionomer cement without varnish: group 4, glass ionomer cement with varnish; group 5, silver glass ionomer cement without varnish; and group 6, silver glass ionomer cement with varnish. Two groups of five roots each were used as positive and negative controls. The root surfaces were coated with nail polish and specimens immersed in 2% methylene blue solution for 14 days. After vertical sectioning, dye penetration was examined under a stereomicroscope. The results of the study were analysed statistically. The sealing ability of the conventional glass ionomer cement with varnish was significantly better while dye penetration was higher in silver glass ionomer cement without varnish group than the other groups (P > 0.01).

The present study compared the compressive, tensile and flexural strengths of 26 commercial glass ionomer cements, which were evaluated 24 h after the beginning of the setting reaction. In order to give a global estimation of their overall strength, a coefficient was attributed to each glass ionomer cement. This strength coefficient provided a ranking of the tested materials. The highest scores were obtained by the restorative glass ionomers; however, these materials exhibited lower mechanical properties than the more classic restorative materials such as amalgams or composites. The results also showed a large scattering of the mechanical properties among the luting and lining glass ionomer cements. The creep behavior of the glass ionomer cements was also investigated.

The physical properties and bond strengths of two glass ionomer materials reinforced with silver and amalgam alloy powders were compared with those of a conventional material from the same manufacture as well as two commercially available products. The diametral tensile strength, hardness and bonding strength are improved with the addition of either commercial available silver particles or fabricated high-copper amalgam alloy powders to the glass. Simple mixture of the metal or alloy powders with the glass ionomer cement seems to be feasible to improve the properties of the regular cement. However, further studies in formulating an optimal composition of metal or alloy, setting characteristics and long-term clinical evaluation are necessary before proposing uses for this new material.

Fifty-one restorations of the tunnel type were performed with "cermet" cement on primary molars. The restorations were assessed clinically, radiographically, and by direct examination of the proximal surface 6 months (group I) and 12 months (group II) after placement. The incidence of fractured marginal ridges was found to be 3.8% in group I and 4.2% in group II. All restorations had their occlusal portion intact and were caries-free. Clinically detectable occlusal wear was found in 7.7% of teeth in group I and in 4.2% of teeth in group II. No correlation was found between direct and radiographic assessment of proximal caries. White spots, without carious penetration, were detected on 53.8% of proximal surfaces at 6 months and on 60.0% of proximal surfaces at 12 months.

Biofilms colonizing pipe surfaces of drinking water distribution systems could provide habitat and shelter for pathogenic viruses present in the water phase. This study aims (i) to develop a method to detect viral particles present in a drinking water biofilm and (ii) to study viral interactions with drinking water biofilms. A pilot scale system was used to develop drinking water biofilms on 3 materials (7 cm2 discs): PVC, cast iron and cement. Biofilms were inoculated with viral model including MS2, PhiX174 or adenovirus. Five techniques were tested to recover virus from biofilms. The most efficient uses beef extract and glycine at pH = 9. After sonication and centrifugation, the pH of the supernatant is neutralized prior to viral analysis. The calculated recovery rates varied from 29.3 to 74.6% depending on the virus (MS2 or PhiX174) and the material. Applying this protocol, the interactions of virus models (MS2 and adenovirus) with drinking water biofilms were compared. Our results show that adsorption of viruses to biofilms depends on their isoelectric points, the disc material and the hydrodynamic conditions. Applying hydrodynamic conditions similar to those existing in drinking water networks resulted in a viral adsorption corresponding to less than 1% of the initial viral load.

Most commercial dental composites contain liquid dimethacrylate monomers (including BIS-GMA or variations of it) and silica-containing compositions as inorganic reinforcing filler particles coated with methacrylate-functional silane coupling agents to bond the resin to the filler. They also contain initiators, accelerators, photo-initiators, photosensitizers, polymerization inhibitors, and UV absorbers.Durability is a major problem with posterior composites. The typical life-span of posterior composites is from three to 10 years, with large fillings usually fewer than five years. Polymerization shrinkage and inadequate adhesion to cavity walls are remaining problems. Some pulp irritation can occur if deep restorations are not placed over a protective film. Some have advocated the use of glass-ionomer cement as a lining under resin composite restorations in dentin.The concept of glass-ionomer cements (GICs) was introduced to the dental profession in the early 1970's. Current GICs may contain poly(acrylic acid) or a copolymer. Higher-molecular-weight copolymers may also be used to improve the physical properties of some GICs. Stronger and less-brittle hybrid materials have been produced by the addition of watersoluble compatible polymers to form light-curing GIC formulations.The ion-leachable aluminosilicate glass powder, in an aqueous solution of a polymer or copolymer of acrylic acid, is attacked by the hydrated protons of the acid, causing the release of aluminum and calcium ions. Salt bridges are formed, and a gel matrix surrounds the unreacted glass particles. The matrix is adhesive to mineralized tissues. Provisions must be made for maintenance of the water balance of restorations for the first 24 hours. A varnish to seal newly-placed restorations is provided by most manufacturers. The introduction of metal powder to GICs significantly improved abrasion resistance.

Standardized plastic analogues simulating an endodontically treated maxillary central incisor root were used to investigate the resistance to root fracture in endodontically treated teeth. Three different post and core systems were used: (1) cast post and core, (2) Para-Post Plus post, and (3) Flexi-Post post. The core build-up material selected in this study was Ketac Silver material, after which a crown preparation was made on each analogue. Two types of preparations were used: a wide chamfer margin (butt-joint) and a wide chamfer margin with a 1.0 mm circumferential bevel. An overcasting was fabricated and was permanently cemented on each preparation. Assemblies were subjected to an increasing lingual oblique force until fracture occurred. Results were tabulated using the analysis of variance (F test) and Student's t test. Beveled preparations with a concomitant final restoration provided a significant increased resistance to root fracture. Furthermore, vertical fracture occurred twice as often with nonbeveled preparations.

The clinical potential of the tunnel restoration is restrained by perceived difficulties of access to proximal caries and lack of long-term clinical data. This paper describes a technique that affords proximal access similar to that of a standard Class II cavity preparation and provides an evaluation of a technique, using capsulated glass ionomer cements. It is supported by more than nine years of clinical experience that confirms the viability of this procedure as an alternative to conventional Class II cavity restorations for initial proximal lesions.

Ninety-one extracted maxillary premolar teeth were restored with a prefabricated post and amalgam, composite resin or glass-cermet core. Each group was again divided into three groups of 9-13 teeth to be subjected to an increasing load in one of three standardized directions (10, 45 and 90 degrees to the long axis of the tooth). Failure load and characteristics of failure were recorded. The glass-cermet-restored teeth had a lower strength than the other groups for every load direction (Student's t-test: P less than 0.01). Amalgam and composite resin groups showed a significant difference only for the 10 degrees loading condition (Student's t-test: P less than 0.02). Teeth restored with amalgam cores displayed a higher mean failure load, in combination with a 46% occurrence of root fracture.

Metal reinforced glass-ionomer cements are said to possess superior mechanical properties when compared to non-metal reinforced glass-ionomer cements. However, the literature to date does not always support this view, owing to the variety of materials and test methods employed. In this study the mechanical properties of three reinforced and three standard materials were tested using the standard specification tests of compressive and diametral strength in addition to tensile strength using the four point bend test. The tensile strength was also measured using the shell test in order that this test, which on theoretical grounds is more suited to these materials, may be evaluated. Six specimens of each material were prepared for each of the test modalities resulting in the conclusion that the addition of metal to glass-ionomer cements can markedly increase the strength of the materials. However, the method of fusing the metal to the glass rather than by simple addition does not produce any advantages in strength. In this evaluation one reinforced material was significantly stronger than all other materials in all four test modalities. The compressive strength test which appears in most standards does not appear to be very discriminatory. Of the tensile tests, which have more clinical significance, the results of the diametral strength tests, which are included in some standards, appear to be at variance with the other two tensile tests, suggesting that the flexural or shell test would be more appropriate.

This study measured the in vitro inhibition of growth and adherence of five oral bacteria by glass-ionomer materials. Disks were prepared from two cavity liners and four restorative class materials, by use of Teflon plates with circular wells, five mm wide and two mm deep. The bacterial species tested included: A. viscosus, S. mitis, S. mutans, L. casei, and S. sanguis. Growth inhibition studies were performed by the spreading of 0.1 mL of standardized inocula over agar plates produced with selective media, followed by the direct application of glass-ionomer disks onto the agar. On other plates, disks were placed onto uninoculated agars for 48 h, followed by bacterial inoculation. All agar plates were incubated under optimal growth conditions for each bacterial species. The four restorative materials were also placed aseptically into sterilized bovine incisors and placed into sucrose containing broth media, inoculated with S. mutans for three days. Adhering materials were disclosed and scored. An ion-exchange electrode was used to measure fluoride release over a seven-day period for all six glass ionomers. The two cavity liners and two of the restorative materials produced the largest growth inhibition zones by direct contact. No growth inhibition occurred when the specimens were allowed to come into contact with the agars prior to inoculation. All four restorative materials reduced bacterial accumulations on enamel surfaces by over 80%. Elevations in short-term fluoride release levels were positively correlated with growth inhibition.

In order to study the effects of different glass ionomers on the metabolism of Streptococcus mutans, test slabs of freshly mixed conventional glass ionomer (Fuji), silver glass ionomer (Ketac-Silver), composite (Silux), and 2-week-old Fuji were fitted into the bottom of a test tube. A plaque-like layer of S. mutans strain Ingbritt was centrifuged onto the test slabs, and the samples were incubated for 20 h in 1.7% (w/v) sucrose solution. For freshly mixed Fuji and Ketac-Silver, the pH fall was significantly smaller than for old Fuji and composite. These materials also released the largest amount of fluoride into the fluid phase. Incubation with glass ionomer materials led to an increase in the cellular concentration of fluoride in bacteria, but intracellular fluoride did not correlate with the fall in pH. The lowest pH was associated with the lowest cellular magnesium content. Ketac-Silver released large amounts of calcium in the fluid phase, and the cellular calcium content was doubled in this group. The results show that freshly mixed glass ionomers affect acid production and electrolyte metabolism of S. mutans in vitro. The effect of conventional glass ionomer, however, seems to disappear after a few weeks. The effects of calcium and silver released by cermet glass ionomer deserve further study.

Furcation perforations sealed with silver glass ionomer cement (Chelon Silver) were evaluated in vitro compared with amalgam. Access cavities were prepared in 25 extracted human molar teeth. The coronal orifices of the root canals were sealed with amalgam and varnish. Naturally occurring coronal leakage through the intact pulp chamber floor was determined quantitatively for each tooth, using a modified fluid transport model, under pressure of 1.2 Atm. Each tooth was then disconnected from the system, perforated at the furcation, and the perforation sealed with either Chelon Silver (10 teeth) or amalgam (10 teeth); five remaining teeth served as a negative control. After incubation for 24 h at 37 degrees C in 100% humidity, teeth were reconnected to the modified fluid transport system, and coronal leakage under pressure was evaluated at 1, 2, 6, 15, and 24 h. Leakage through each tooth was compared with that of its own intact pulp chamber floor before perforation and the groups compared with each other. No significant difference was found between the mean leakage of the intact pulp chamber floors of the two groups. Chelon Silver had a significantly better sealing ability than amalgam (p0.01): leakage rate of 0.007 and 0.017 microliter/min, respectively. It is concluded that Chelon Silver could be an adequate sealer for furcation perforations.

This study investigated the influence of pins on the fracture resistance of three core materials. Two or four stainless steel pins were incorporated in either amalgam, composite resin, or alloy-reinforced glass ionomer specimens. Half of the pins were surface-treated with mercury, Panavia EX resin, or hydrochloric acid before they were incorporated in the respective materials. The pins were oriented in a direction relative to the tensile stress/axis of the specimen: parallel/perpendicular (PL/PR), perpendicular/parallel (PR/PL), or perpendicular/perpendicular (PR/PR). ANOVA tested significant differences in diametral tensile strength among materials, in number of pins, in pin orientations, in surface treatments, and in other interactions. Incorporation of pins weakened amalgam the most, followed by composite resin. Pins did not weaken amalgam-reinforced glass ionomer. Pin orientation improved the fracture resistance of some specimens by two times that of the controls. Orientation of pins parallel to the tensile stress was most favorable. As the number of pins increased, the fracture resistance of amalgam significantly decreased. Acid treatment of the pin surface enhanced the bond with composite resin. Both treatments resulted in significant improvement in fracture resistance.

The microleakage after retrofillings of amalgam, amalgam with cavity varnish, silver-containing glass ionomer cement, and intermediate restorative material was compared in vitro. Thirty-six extracted human incisors and canines were instrumented, obturated with gutta-percha without sealer, subjected to apicoectomy, and retrofilled with the materials described above. After removal of the gutta-percha filling, the microleakage from both directions (apically and coronally) was measured quantitatively and longitudinally for 24 wk after filling by a fluid filtration technique. All four retrofilling materials revealed some apical and coronal leakage at all time periods. The amalgam group showed statistically significant (p less than 0.001) apical leakage at 1.5 h. The use of cavity varnish significantly reduced the apical leakage of the amalgam group at 1.5 h. The silver-containing glass ionomer cement and intermediate restorative material groups showed significantly (p less than 0.05) less coronal leakage compared with the amalgam group at 1.5 h. Scanning electron microscopy of selected samples showed marginal defects of approximately 5 microns between the root dentin and the retrofilling material.

The present study compares the compressive strength after one week of some conventional glass-ionomer restorative materials with that of glass ionomers reinforced by the addition of ceramic-coated silver or dental amalgam alloy particles to the aluminosilicate glass powder. Apart from the commercially available Ketac Silver and Miracle Mix, experimental mixtures of Fuji II glass-ionomer powder, the old as well as the new version, with various amounts of either a spherical or lathe-cut amalgam alloy were investigated. For the conventional glass ionomers, the mean compressive strength based on all measurements amounts to 159.9 +/- 4.5 MPa. Both formulations of Fuji II have a comparable strength after one-week maturation. The compressive strength of Ketac Silver does not differ significantly from that of Ketac Fill or from that of the conventional glass ionomers investigated. The effect of admixing amalgam alloy on the compressive strength is found to be determined by the shape and the amount of the alloy particles. Moreover, both parameters are interactive with the formulation of the Fuji glass ionomer used for preparation of the mixture. The results indicate that when dental amalgam alloy is added to the glass ionomer, lathe-cut particles are to be preferred but only in an amount up to 20% by weight.

Comparison was made of the apical microleakage of retrograde fillings with amalgam and with silver glass ionomer cements using a modified dye penetration method. Forty instrumented human teeth were divided into four groups. Each group was characterized by a different retrograde filling material or technique: Group 1--silver glass ionomer (SGI); group 2--SGI with previous acid wash of the cavity; group 3--SGI in a previously acid washed cavity, protected with varnish; and group 4--zinc-free amalgam. A paper cone for dye adsorption analysis was placed in contact with retrofill and the main canal was obturated with thermoplasticized gutta-percha. All teeth were coated, immersed in methylene blue dye, and evacuated to assure complete penetration of the dye in any possible void. Later the teeth were cleared and evaluated under stereomicroscope. Statistical analysis showed that group 1 had the least microleakage of all. In addition, the biocompatibility of the SGI and varnish was compared with that of amalgam using the 51Cr release evaluation method. The results showed that SGI and varnish were less cytotoxic than amalgam. It was concluded that SGI cement can be considered an alternative retrograde filling material.

The effect of acid etching on the surface appearance and flexural strength of four glass polyalkenoate cements was investigated. Specimens were etched for intervals of 10-60 s, both at the recommended time after mixing and after a 24-h delay. The surface texture was examined microscopically. Further specimens were subjected to a 4-point bend test following etching 1 h and 24 h after mixing. Deterioration of the surface appearance occurred as the etching time was increased beyond 10 s following immediate etching. Etching after 24 h reduced surface damage, but a 10-s etch still gave the most favourable surface appearance without loss of particulate material. Etching beyond 10 s significantly reduces flexural strength.

This paper reviews our recent studies on fluoride-releasing adhesives and the related studies in this field based on information from original research papers, reviews, and patent literatures. A revolutionary PRG (pre-reacted glass ionomer) filler technology--where fillers were prepared by the acid-base reaction of a fluoroaluminosilicate glass with polyalkenoic acid in water, was newly developed, and a new category as "Giomer" was introduced into the market. On fluoride release capability, SIMS examination revealed in vitro fluoride ion uptake by dentin substrate from the PRG fillers in dental adhesive. On bonding durability, it was found that the improved durability of resin-dentin bonds might be achieved not only via the strengthened dentin due to fluoride ion uptake from the PRG-Ca fillers, but also due to retention of relatively insoluble 4-AETCa formed around remnant apatite crystallites within the hybrid layer in 4-AET-containing self-etching adhesives. On ultramorphological study of the resin-dentin interface, TEM images of the PRG-Ca fillers revealed that the dehydrated hydrogel was barely distinguishable from normal glass fillers, if not for the concurrent presence of remnant, incompletely reacted glass cores. In conclusion, it was expected that uptake of fluoride ions with cariostatic effect from PRG-Ca fillers would endow dentin substrates with the benefit of secondary caries prevention, together with an effective and durable adhesion to dentin.

RDF, the high calorific value fraction of MSW obtained by conventional separation systems, can be employed in technological plants (mainly cement kilns) in order to obtain a useful energy recovery. It is interesting and important to evaluate this possibility within the general framework of waste-to-energy solutions. The solution must be assessed on the basis of different aspects, namely: technological features and clinker characteristics; local atmospheric pollution; the effects of RDF used in cement kilns on the generation of greenhouse gases; the economics of conventional solid fuels substitution and planning perspectives, from the point of view of the destination of RDF and optimal cement kiln policy. The different experiences of this issue throughout Europe are reviewed, and some applications within Italy are also been considered. The main findings of the study are that the use of RDF in cement kilns instead of coal or coke offers environmental benefits in terms of greenhouse gases, while the formation of conventional gaseous pollutants is not a critical aspect. Indeed, the generation of nitrogen oxides can probably be lower because of lower flame temperatures or lower air excess. The presence of chlorinated micro-pollutants is not influenced by the presence of RDF in fuel, whereas depending on the quality of the RDF, some problems could arise compared to the substituted fuel as far as heavy metals are concerned, chiefly the more volatile ones.

Conservative dentistry in developing countries often poses a problem because of lack of expensive dental equipment. This survey was undertaken to test two more appropriate filling materials in vivo. In 94 secondary school students (in Mzuzu, Malawi) with two or more cavities, one cavity was prepared in the conventional way using drilling equipment and then filled with amalgam, and one cavity was prepared using hand instruments only and filled with either cermet ionomer or "miracle mix". Models of the filled teeth (99 amalgam, 53 "miracle mix", 54 cermet ionomer; all of them Class 1) were made and evaluated by three examiners after 6 months and after 1 yr. The fillings were given a score on a four-point scale. One year later all types of filling materials had significantly decreased in quality, but only five fillings (one amalgam, one "miracle mix", and three cermet ionomer) needed replacement. Compared to the amalgam filling in the same mouth, more cermet ionomer and "miracle mix" fillings performed poorly, but these differences were not statistically significant after 1 yr. Both cermet ionomer and "miracle mix" are very promising alternatives for Class I tooth cavities in areas without dental equipment.

– Fluoride was extracted by 1 or 50 ml deionized water from 0.3 ml samples of two conventional and three metal-reinforced glass-ionomer cements. The fluoride concentration was determined by electrode. It was found that the fluoride concentration around the glass-ionomer cements ranged 2–3 ppm after 15 min and 3–5 ppm after 45 min. The maximum fluoride concentration attained within 24 h varied from 15–21 ppm, while the total amount of fluoride released during 100 days varied from about 2 mg fluoride to 12 mg fluoride per ml glass-ionomer cement. An alloy reinforced cement and its conventional counterpart released the highest amount of fluoride whereas a glass-cermet type released the lowest amount. Within the premises of this study it was concluded that composition and handling of the cements are of importance for the release of fluoride, and that a caries inhibitory fluoride concentration can be established in the surroundings of all of the cements.

In this study, scanning electron microscopy and x-ray microanalysis techniques were used to examine a silver-reinforced glass ionomer cement. Scanning electron microscopy was used to evaluate surface topography and microstructure. Microcracking and a bimodal pore distribution were observed. The cement consisted of unreacted glass particles surrounded by a silica gel “halo” and embedded in an organic salt matrix. Back-scattered electron microscopy and energy-dispersive spectroscopy detected discrete clusters of silver atoms within the material. Other elements, such as calcium and aluminum, were dispersed homogeneously. Wavelength dispersive spectroscopy was used to detect fluoride, which also appeared to be homogeneously distributed. Electron microscopy and x-ray microanalysis techniques could prove valuable in clarifying the microstructure and fluoride release mechanism of glass ionomer cements. Refinement of some aspects, including sample preparation, will be necessary to obtain consistently reliable results.

Premolar teeth with Class II amalgam restorations placed after the application of cavity varnish (Group A), a light cured glass ionomer base (Group B) and 40 per cent polyacrylic acid as a pretreatment agent, followed by unset cermet cement (Group C) were examined for marginal leakage using dye penetration and image analysis. Including amongst the parameters examined were linear leakage length and leakage area, which were found to have no consistent correlation. Group A and C did not generally show significant differences in the parameters examined, whereas Group B exhibited significantly less linear leakage (P less than 0.001), and significantly less leakage area when the stained area was expressed as a percentage of available dentine (P less than 0.001). While allowing some linear leakage, it was found that the light cured glass ionomer base appeared to prevent the dye from entering the dentine. It is concluded that an assessment based solely on the leakage length is inadequate and that some measurement of penetration into dentine should be included in order to fully assess the microleakage potential of a material or technique.

Summary. The usefulness of glass ionomer cements in endodontics is illustrated by selected case histories. The situations varied from root repair to root end filling. The use of regular glass ionomer cement and a reinforced version are presented. In addition, the preparation of a modified glass ionomer cement, that could be used alone, or with gutta-percha, for root canal obturation is described.

Levels of mutans streptococci in plaque samples from margins of Class II amalgam (Dispersalloy), composite (P-10), and glass-ionomer (Ketac Silver) restorations were compared. Fifty-one children, each having one of the restorations in a permanent first molar, were part of an inter-individual comparison, giving 17 restorations of each material. The age of the children, the age of the restorations, and the salivary levels of mutans streptococci were comparable in the three groups. Another seven children-each having both a composite and a glass-ionomer restoration of the same age placed on contralateral premolar or molar teeth-were part of an intra-individual comparison. The percentage mutans streptococci of total CFU count in plaque was higher on composite (mean 13.7) and amalgam (mean 4.3) than on glass-ionomer (mean 1.1) restorations in the inter-individual comparison, and higher on composite (mean 4.2) than on glass-ionomer (mean 0.4) restorations in the intra-individual comparison. In both comparisons, the differences in values between samples from glass-ionomer restorations and samples from composite or amalgam restorations were statistically significant (p

– Proximal cavities with or without a dovetail were prepared in primary molars of 5-7-yr-old children. The cavities were filled with either a traditional glass ionomer (Ketac-Fil) or a cermet (Ketac-Silver). A total number of 199 treated teeth were available for evaluation 5-14 months after placement of the fillings. The percentage of success was 84% for Ketac-Fil and 77% for Ketac-Silver. There was no clear difference in rate success between the two different types of cavities.

Interproximal plaque samples were collected from newly made class II conventional conservative amalgam (Dispersalloy) and glass ionomer (Ketac Silver) tunnel restorations in 20 adolescents. The percentage viable count of mutans streptococci in samples from glass ionomer restorations (mean 3.1%, median 0.7%) was significantly lower (p less than 0.05) than in samples from amalgam restorations (mean 5.7%, median 3.1%). This suggests that plaque formed on such restorations might have a lower potential to induce recurrent caries than plaque formed on amalgam restorations.

Cermet ionomer cements are sintered metal/glass powders, which can be made to react with poly(acids). These new cements are significantly more resistant to abrasion than regular glass ionomer cements and are widely accepted as core build-up materials and lining cements. They can strengthen teeth and provide the clinician with an opportunity to treat early dental caries.

The purpose of this study was to design an experimental model that allowed extensive endodontic interim restorations to be tested for dye penetration while under simulated masticatory load. Extracted premolar teeth had standardized mesio-occluso-distal cavities prepared, and the root canals were instrumented. A cotton wool pellet was placed in the pulp chamber, and the cavities were restored with Cavit, IRM, Ketac-Fil Plus, Ketac-Silver, or composite resin (Z100). They were subjected to the equivalent of 3 months of clinical load while exposed to methylene blue dye. Results of this study could not support IRM as a suitable interim endodontic restorative material to use in extensive cavities. The dye penetration in the Ketac-Fil Plus and Ketac-Silver specimens was not predictable, and the results suggested Cavit and Z100 composite resin require further investigations as potentially useful materials for this purpose.

Objective To investigate the load-bearing capacity and failure mode of various types of glass ionomer cement (GIC) under Hertzian indentation, exploring the relationship between the failure behavior and formulation, and examining claims of filler-reinforcement of GIC. Methods Discs 2 mm thick, 10 mm diameter, 8–18 replicates, were fabricated for two filler-reinforced GICs, four unmodified and unreinforced GICs, and four resin-modified GICs, with a dental silver amalgam and a filled-resin restorative material for comparison. Testing was at 23 °C, wet, after 7 d storage at 37 °C in artificial saliva at pH 6, using a 20 mm diameter hard steel ball and filled-nylon substrate ( E : 10 GPa). First failure was detected acoustically; mode was determined visually. At least 1/3 of specimens in each case were examined under scanning electronic microscope for corroboration. Results Reinforced and unmodified-unreinforced GICs were indistinguishable by failure load (one-way analysis of variance, P = 0.425, overall 260 ± 70 N) and mode. Failure loads for resin-modified GICs were 360–1150 N, amalgam ∼680 N, and filled resin ∼1200 N. Resin-modified GICs tended to be tougher (incomplete fracture), all others gave complete fracture (radial cracking). The stronger materials (two resin-modified GICs and filled resin) showed some cone cracking. Significance While resin-modified GICs showed various extents of increase of failure load over that of the plain GICs, consistent with the hybrid chemistry, filler-reinforcement was not evident for the two claimed products, consistent with structural and theoretical expectations.

This study evaluated the retention of dental post heads (No. 2 Flexi-Post) embedded in 5 core materials (1 automix resin composite, 2 hand-mixed resin composites, and 2 glass ionomers).Samples were prepared by embedding post heads in 4.5-mm-thick disks of core material.The resin composite materials provided significantly more retention than the glass-ionomer-based materials. The post head retention of the automix resin composite was comparable to that of the hand-mixed resin composites.Unlike the resin composite samples, all the glass-ionomer samples fractured during testing. This is an unacceptable condition for a clinically successful restoration.

Characteristics of a new cermet X-ray tube for mammography are considered. The results of experimental testing of the tube are described.

Glass ionomer cements (GIC) have been modified in an attempt to improve their mechanical properties. The objective of the present paper was to compare the two-body and three-body wear of four modified GIC. The tested materials were Fuji IX (GC Corporation), Hi-Fi (Shofu) and Ketac Molar Aplicap (3M/ESPE). The cermet cement Ketac Silver Maxicap (3M/ESPE) was used as reference material.Two-body wear tests were carried out in the computer controlled 'artificial mouth' of the Munich Dental School, three-body wear was tested with the ACTA wear machine.The resulting average two-body wear rates (in microm) were: Fuji IX 327 (SD +/- 82)Ketac Molar 379 (SD +/- 94)Hi-Fi 376 (SD +/- 90)Ketac silver 449 (SD +/- 127). The differences between the materials were significant (P0.05, ANOVA, modified LSD-test) with the exception of Ketac Molar and Hi-Fi. The average three-body wear rates (in microm) were: Hi-Fi 30 (SD +/- 10)Ketac Molar +/- 42 (SD +/- 12)Fuji IX 49 (SD +/- 14)Ketac silver 73 (SD +/- 23). The difference between Ketac silver and the three other materials was significant (P0.05, ANOVA, modified LSD-test). No significant difference was calculated between Hi-Fi, Ketac Molar and Fuji IX.As Ketac Molar, Hi-Fi and Fuji IX show better wear resistance compared to Ketac silver both in occlusal-contact and contact-free areas, it may be assumed that the wear resistance of a glass ionomer cement may be improved more by changing the powder: liquid ratio than by incorporating silver particles into the glass powder.

Objectives: The purpose of this study was to investigate the long-term performance of tunnel restorations. Methods: Thirty-three glass polyalkenoate (ionomer) or cermet restorations were placed in the premolar or first molar teeth of 25 patients. Conservative amalgam control restorations were the means of treatment in 14 similar teeth of the same group. Review as to performance consisted of a regular clinical and radiographic examination and the criteria for failure were recurrent caries, fracture of the marginal ridge or gross loss of restorative material. Results: After 3 years all types of restoration were satisfactory. By approximately 5 years one-quarter of the glass ionomer and 10% of the cermet restorations had failed. All the failures after any period of service could be replaced by conservative amalgam fillings. None of the controls required replacement. Conclusion: While tunnel restorations employing glass ionomer material and the cermet variant do enjoy a degree of success, this preliminary work suggests that small restorations of dental amalgam are more successful in the long term.

An investigation regarding possible artefacts from dental filling materials in MR imaging is presented including 9 types of such materials from various manufacturers. Freshly extracted teeth were prepared and the filling materials were handled according to manufacturers' instructions. The teeth were encapsulated into a gel phantom based on de-ionized water, Ni (NO3)2 and polysaccharide agarose powder. The investigation was performed with a standard head coil and a 1.5 T MR unit. Images acquired with various combinations of parameters from different sequences were visually analysed regarding possible artefacts. The investigation showed that only one of the materials caused significant artefacts. The gel phantom was found to be a valuable means for examination of artefacts from small samples, and can be recommended as a standard technique for this purpose.

The restorative materials amalgam (Standalloy F) and glass ionomer cements (Chelon Silver) were comparatively investigated to determine the number of mutans streptococciSaliva and plaque were collected from patients before and 40 days after the insertion of their restorations.Total bateria and mutans streptococci counts were found to be statistically significantly reduced when compared with the prerestoration counts in the saliva samples (P0.001). Microbiological analysis of the dental plaque showed that the number of mutans streptococci in the glass ionomer cements was significantly lower than in the amalgam restorations (P0.001).This study showed that silver glass ionomer cements inhibited the growth of mutans streptococci.

This study was undertaken to measure physical properties of materials used for direct core buildups, including high-copper amalgam, visible light-cured resin composite, autocured titanium-containing composite, polyacid-modified composite, resin-modified glass-ionomer, and silver cermet cement. Compressive strength, diametral tensile strength, and flexural strength of six core materials of various material classes were measured for each material as a function of time up to 3 months at different storage conditions, using a standard specification test designed for the materials. Three different storage conditions (dry, humid, wet) at 37 degrees C were chosen. Materials were manipulated according to manufacturers' instructions for use as cores. Mean compressive, diametral tensile, and flexural strengths with associated standard deviations were calculated for each material. Multiple comparison and Newman-Keuls tests discerned many differences among materials. All materials were found to meet the minimum specification requirements, except in terms of flexural strength for amalgam after 1 hour and the silver cermet at all time intervals.

The composition of glasses used in glass-ionomer cements affects their leaching behavior and hence the properties of the cement. The aim of this study was to correlate the composition and leaching behavior of these glasses with their infrared absorption characteristics. The wavenumber of the absorption band of the Si-O asymmetric stretching vibration ῡAS shifts to a higher value with decreasing content of mono- and bivalent cations in the glass. This effect can be ascribed to the influence of these extraneous ions on the glass network order and connectivity. Preferential leaching of these ions induces an increase of ῡAS and a general modification of the band profile. The results can be correlated with the x-ray diffraction characteristics of the glass. A decrease in the Si-O-Si angle could be caused by a decrease in the distortions in the (arrangement of the) SiO4 tetrahedra; the tetrahedra as well as their arrangement can be distorted.

Objectives: Experimental glass-silica-metal hybrid composites (polycomposites) were developed and tested mechanically and radiographically in this fundamental pilot study. To determine whether mechanical properties of a glass-silica filled two-paste dental composite based on a Bis-GMA/polyglycol dimethacrylate blend could be improved through the incorporation of titanium (Ti) particles (particle size ranging from 1 to 3 μm) or silver-tin-copper (Ag-Sn-Cu) particles (particle size ranging from 1 to 50 μm) we measured the diametral tensile strength, fracture toughness and radiopacity of five composites. Methods: The five materials were: I, the original unmodified composite (control group); II, as group I but containing 5% (wt/wt) of Ti particles; III, as group II but with Ti particles treated with 4-methacryloyloxyethyl trimellitate anhydride (4-META) to promote Ti-resin bonding; IV, as group I but containing 5% (wt/wt) of Ag-Sn-Cu particles; and V, as group IV but with the metal particles treated with 4-META. Ten specimens of each group were tested in a standard diametral tensile strength test and a fracture toughness test using a single-edge notched sample design and five specimens of each group were tested using a radiopacity test. Results: The diametral tensile strength increased statistically significantly after incorporation of Ti treated with 4-META, as tested by ANOVA ( P =0.004) and Fisher's LSD test. A statistically significant increase of fracture toughness was observed between the control group and groups II, III and V as tested by ANOVA ( P =0.003) and Fisher's LSD test. All other groups showed no statistically significant increase in diametral tensile strength and fracture toughness respectively when compared to their control groups. No statistically significant increase in radiopacity was found between the control group and the Ti filled composite, whereas a statistically significant increase in radiopacity was found between the control group and the Ag-Sn-Cu filled composite as tested by ANOVA ( P =0.000) and Fisher's LSD procedure. Significance: The introduction of titanium and silver-tin-copper fillers has potential as added components in composites to provide increased mechanical strength and radiopacity, for example for use in core materials.

This study calculated the flexural strength for six reinforced restorative materials and demonstrated that flexural strength values can be determined simply by using physical parameters (diametral tensile strength and Young's modulus values) that are easily determined experimentally. A one-way ANOVA analysis demonstrated a statistically significant difference between the two reinforced glass ionomers and the four composite resin materials, with the composite resin being stronger than the glass ionomers.

Objective. To compare the clinical and radiographic treatment outcome of retrograde root filling with either dentin-bonded resin composite (Retroplast, RP) or glass ionomer cement (Chelon-Silver, CS). Study design. A prospective, randomized clinical study of 134 consecutive patients with indication of retrograde root filling of an incisor, canine, premolar, or first molar. Either RP or CS was chosen at random as retrograde filling material. Either material was applied onto the entire resection surface after prepared slightly concave. This preparation technique makes a sealing of the entire resection surface possible and prevents marginal contraction gaps during polymerization. A total of 122 patients were available for 1-year follow-up. Results. After 1 year the proportion of successful cases was significantly higher in the RP group (73%) than in the CS group (31%) (p

This study investigated the wear resistance of three restorative reinforced glass ionomer cements (Fuji IX GP FAST [FJ], Miracle Mix [MM] and Ketac Silver [KS]). Microfilled (Silux [SX]) and mini-filled (Z100 [ZO]) composites were used for comparison. Six specimens were made for each material. The specimens were conditioned for one week in distilled water at 37 degrees C and subjected to wear testing at 20 MPa contact stress against SS304 counterbodies using a reciprocal compression-sliding wear instrumentation. Distilled water was used as lubricant. Wear depth (microm) was measured using profilometry every 2,000 cycles up to 10,000 cycles. Results were analyzed using ANOVA/Scheffe's test (p0.05). After 10,000 cycles of wear testing, ranking was as follows: KSZOMMFJSX. Wear ranged from 26.1 microm for SX to 71.5 microm for KS. The wear resistance of KS was significantly lower than FJ, MM and SX at all wear intervals. Although KS had significantly more wear than ZO at 2,000 to 6,000 cycles, no significant difference in wear was observed between these two materials at 8,000 and 10,000 cycles. Sintering of silver particles to glass ionomer cement (KS) did not appear to improve wear resistance. The simple addition of amalgam alloy to glass ionomer may improve wear resistance but results in poor aesthetics (silver-black color). FJ, which relies on improved chemistry instead of metal fillers, showed comparable wear resistance to the composites evaluated and is tooth-colored. It may serve as a potential substitute for composites in low-stress situations where fluoride release is desirable and aesthetic requirements are not high.

The aim of this study was to analyze factors influencing the failures of tunnel restorations performed with a glass cermet cement (Ketac Silver). Caries activity, lesion size, tunnel cavity opening size, partial or total tunnel, composite lamination or operating time showed no significant correlation to failure rate. Twelve dentists in eight clinics clinically experienced and familiar with the tunnel technique placed 374 restorations. The occlusal sections of fifty percent of the restorations were laminated with hybrid resin composite. The results of the yearly clinical and radiographic evaluations over the course of 3 years were correlated to factors that could influence the failure rate using logistic regression analysis. At the 3-year recall a cumulative number of 305 restorations were available. The cumulative replacement rate was 20%. The main reasons for replacement were marginal ridge fracture (14%) and dentin caries (3%). Another 7% of the restorations which had not been replaced were classified as failures because of untreated dentin caries. The only significant variable observed was the individual failure rate of the participating dentists varying between 9 and 50% (p=0.013).

Controversy exists over the most favorable material and type of restoration to be used to transitionally restore teeth destined to be crowned. This in vitro study uses fracture resistance testing to compare eight different transitional restorations in maxillary premolars. Ninety sound maxillary premolars were randomly selected and allocated to nine groups, each comprising 10 teeth. One group remained unrestored and was used as the control. Teeth in the remaining groups were prepared to a standard cavity form using: a copy milling process removing the palatal cusp. Restorations were placed using amalgam with dentin pins and cavity varnish; amalgam with an amalgam bonding agent; resin composite with dentin pins and a dentin bonding agent; resin composite with a dentin bonding agent only; resin-modified glass ionomer with dentin pins; resin-modified glass ionomer cement alone and cermet with dentin pins and cermet alone. Each restored tooth was then subjected to axial loading via a bar contacting the buccal and restored palatal cusps until failure of the restored tooth occurred. The mean load-to-fracture values were statistically compared and the modes of failure recorded. It was found that the choice of restorative material and type of restoration had little effect on the fracture resistance of the restored tooth with the exception of those teeth restored with reinforced glass ionomer cement alone, which exhibited a significantly lower resistance to fracture than the other restored teeth. However, the choice of restorative material/technique did influence the mode of failure. Failure in teeth restored with resin-modified glass ionomer cement alone produced the least damage to the remaining tooth tissue when failure occurred. Consequently, this material may offer the most favorable range of properties for the transitional restoration of extensively broken-down maxillary premolar teeth destined to be crowned. Furthermore, the findings of this study fail to support the use of dentin pins in the placement of bonded build-up restorations.

The purpose of this study was to assess the cytotoxicity of some commonly used glass ionomers. Three chemically cured glass ionomers (Fuji II, Lining cement, and Ketac Silver) and one light-cured (Fuji II LC) were tested. Extracts of mixed non-polymerized materials and polymerized specimens were prepared in accordance with ISO standard 10993-12. The polymerized specimens were cured and placed either directly in the medium (freshly cured), left for 24 h (aged), or aged plus ground before being placed in the medium. The cytotoxicity of extracts was evaluated on mouse fibroblasts (L, 929), using dimethylthiazol diphenyltetrazolium (MTT) and neutral red (NR) assays. Further, the concentrations of aluminum, arsenic and lead were analyzed in aqueous extracts from freshly cured and aged samples, and the fluoride levels analyzed in aqueous extracts from freshly cured samples. All extracts except that of non-polymerized Ketac Silver were rated as severely cytotoxic in both assays. Extracts of polymerized material were significantly more cytotoxic than extracts of non-polymerized material. All freshly cured glass ionomers released aluminum and fluoride concentrations far above what is considered cytotoxic (aluminum0.2 ppm and fluoride20 ppm). Extracts from freshly cured Lining Cement contained the highest concentrations of aluminum and fluoride (215 ppm and 112 ppm). Extracts from freshly cured Ketac Silver had the lowest concentrations of aluminum and fluoride but the highest of lead (100 ppm). It can be concluded that all extracts from non-cured, freshly cured, and aged glass ionomers contained cytotoxic levels of substances. Curing did not reduce the toxicity significantly.

The objective of this study was to determine long term release of fluoride from a resin-modified glass-ionomer cement (RMGIC) (Fuji II LC (FLC)) compared with that from two conventional acid-base setting cements (HiDense (HD) and KetacSilver (KS)) marketed for similar restorative purposes. Fluoride release from discs of cement immersed in water or artificial saliva was measured for 2.7 years using an ion selective electrode technique. The RMGIC was affected by water if immersed immediately after setting. This is similar to conventional acid-base cements and the experimental method was designed to allow for this. Over the 2.7-year period, the RMGIC and HD released similar amounts of fluoride into both water and artificial saliva. In water, the RMGIC released the most fluoride, while in artificial saliva the highest release was from HD. KS released the least amount of fluoride in both immersing liquids. In artificial saliva, release was reduced to 17-25% of that found in water, with the RMGIC showing the greatest reduction. Both acid-base cured cements showed changes in colour over the 2.7-year span, while the colour of the RMGIC was stable. It was concluded that the RMGIC released equivalent or greater amounts of fluoride than the two acid-base cure glass-ionomers over a period of 2.7 years.