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PubMed2000

Clinical performance of bonded amalgam restorations at 42 months.

BACKGROUND: Despite a lack of data based on clinical research, many positive characteristics have been attributed to the placement of amalgam restorations with an adhesive resin liner. METHODS: For 42 months, and authors followed two groups of subjects who had amalgam restorations placed in a previous study. In this double-blind study, these subjects had been randomly assigned to have amalgam restorations placed with an adhesive liner or with a copal varnish placed under all restorations and a bulk base of zinc phosphate cement for deeper lesions. The authors evaluated anatomical form, marginal adaptation, retention and the presence of secondary caries at six, 18, 30 and 42 months. RESULTS: At 42 months, the authors found that all restorations in both groups still were retained, were free of secondary caries and were rated clinically acceptable. No difference between the groups was found for any category (P > .05; analysis). CONCLUSIONS: Placement of amalgam restorations with adhesive liners was found to produce results equivalent to that of traditional methods over a 42-month period. CLINICAL IMPLICATIONS: Practitioners wary of using new methods that have not undergone thorough clinical testing can feel comfortable placing adhesive liners under amalgam restorations.

Chi-Square Distribution↗
PubMed2000

Statistical tests.

Explore the source record for details and available documents.

Data Interpretation, Statistical↗
PubMed2001

The performance of bonded vs. pin-retained complex amalgam restorations: a five-year clinical evaluation.

BACKGROUND: The authors compared the clinical performance of complex amalgam restorations, replacing at least one cusp--retained either mechanically with self-threading pins or bonded--with a filled, 4-methacryloxyethyl trimellitate anhydride, or 4-META-based resin designed for amalgam bonding. METHODS: The authors placed 60 amalgam restorations (28 pin-retained and 32 bonded), each restoration replacing at least one cusp. They used self-threading stainless steel pins in the pin-retained group and a filled, 4-META-based bonding resin in the bonded group. For both groups, the authors left in place any retention form remaining after removal of an old restoration but did not enhance it. RESULTS: At four years, six restorations had failed. At five years, of the 40 restorations available for evaluation, three had failed, for a total of nine failed restorations; seven of those were pin-retained and two were bonded. Using the Fisher exact test to compare the groups at five years, the authors found no significant difference in failure rate, marginal adaptation, marginal discoloration, secondary caries, tooth sensitivity or tooth vitality. CONCLUSIONS: At five years, there was no difference in the performance of pin-retained amalgam restorations and bonded amalgam restorations. This study will be continued for at least a sixth year. CLINICAL IMPLICATIONS: Bonding with a filled, 4-META-based bonding resin appears to be a satisfactory method of retaining large amalgam restorations replacing cusps.

Acrylic Resins↗
PubMed1999

[Light-induced control of polymerization shrinkage of dental composites by generating temporary hardness gradients].

Irradiation of light-curing dental filling materials in a single direction results in a temporary hardness gradient in the direction of the irradiation. The photoactivated polymerisation process begins at the site of the highest light intensity. In the simplest possible model, the polymerizing composites irradiated in a single direction shows three adjacent co-existing phases: an almost hardened, a gelled and a still plastic phase. As long as all three phases are present, any shrinking of the contracting phases can be compensated by the plastic phase. A knowledge of the distribution of these phases and their spatial and temporal modulation by the selection of suitable curing light parameters provides simple techniques for reducing shrinkage gaps around voluminous fillings in large dental cavities.

Composite Resins↗
PubMed1975

Reaction of the human dental pulp to silver amalgam restorations. The modifying effect of treatment with calcium hydroxide.

Cavities were prepared in 43 bicuspid teeth using two general categories of cavity depth. In the "deep" cavities the bottom was placed in the inner third of the dentin. In the "intermediate depth" cavities the bottom was positioned in the middle third of the dentin. The bottom of the cavities was either rubbed with calcium hydroxide, covered with calcium hydroxide, or left unlined before filling according to the wet amalgam technique. The teeth were extracted after 1 week and examined histologically. All cases, except 2 with deep and 1 with intermediate depth rubbed cavities, showed local vascular dilatation in the pulp underneath the cavity. In addition, all teeth with deep unlined cavities showed inflammatory cells as did 1 with an intermediate depth unlined cavity. There were fewer displaced odontoblast nuclei in the dentin in the calcium hydroxide-treated groups. The milder reactions in the rubbed or covered groups are probably due to the restrictive effect by calcium hydroxide on penetration of amalgam components. In the teeth with deep cavities there were only minor differences between the ones which had been rubbed and those which had been covered with calcium hydroxide.

Calcium Hydroxide↗
PubMed1976

Dental amalgam stabilization by selective interfacial amalgamation.

The purpose of this investigation was to explore the feasibility of enhancing the electrochemical stability of dental amalgam restorations by a process of "selective interfacial amalgamation." If dental amalgam restorations can be selectively alloyed at the tooth-amalgam interface, to a minor thickness as compared with the dimensions of the bulk amalgam, so as to present a more electrochemically stable phase than psi2 to the oral environment, corrosion will be reduced and desirable qualities of existing amalgams can be utilized. It was found that selective interfacial amalgamation was indeed possible and that it could be readily accomplished using a silver suspension as a cavity liner. By then placing a conventional silver-tin amalgam according to ordinary dental techniques, mercury expressed during hand condensing reacted with the silver in the liner resulting in the formation of an integral amalgam restoration with the more noble psi1 phase adjacent to tooth structure. In vitro corrosion tests of samples so prepared exhibited corrosion resistance far superior to unlined control samples.

Corrosion↗
PubMed1980

An evaluation of the marginal seal of amalgam using S.I.A.

The Selective Interfacial Amalgamation (S.I.A.) amalgam linear system was evaluated for its ability to reduce marginal leakage in freshly placed amalgam restorations. Leakage was evaluated in extracted and restored human molars which had been submerged in methylene blue dye for seven days at 37 C. The results shows a statistically significant difference (P less than 0.01) in the leakage of teeth restored using the S.I.A. liner and amalgam as compared to Copalite and amalgam restorations with the S.I.A. restoration proving to be superior.

Acrylates↗
PubMed1992

Thermal coefficients of paste-paste type pulp capping cements.

Thermal coefficients of four kinds of commercially available paste-paste type pulp capping cements were examined. Control reference samples were made of dentin. A thermal coefficient analyzer was used, heating specimens for a few nanoseconds by a xenon flash bulb and measuring thermal changes by using a thermocouple. Thermal coefficients were examined by this non-steady state method. Thermal conductivities of all cements were almost the same or lower than that of dentin. Therefore, when each cement was heated, the penetrating energy was almost the same or lower than that of dentin. The thickness of the cements was converted into that of the dentin by using the obtained thermal conductivity. The 1-mm thickness of the examined cements were equal to between 0.97-mm and 2.10-mm thicknesses of lost dentin. The use of a pulp capping cement provided better pulp protection from thermal stimuli than did the same thickness of dentin.

Calcium Hydroxide↗
PubMed1995

Flexural properties of resin-modified "hybrid" glass-ionomers in comparison with conventional acid-base glass-ionomers.

The mechanical properties of resin-modified "hybrid" glass-ionomers, for both restorative and liner/base applications, were assessed by a flexural test and compared with those of conventional acid-base glass-ionomers. Flexural strength, flexural modulus, and the modulus of resilience were determined 30 minutes after mixing, and at 24 hours and 3 months after aging in distilled water at 37 degrees C. With a microscope and SEM observations, a comparison of marginal breakdown was made between a resin-modified and a conventional glass-ionomer restoration in bovine cavities, after cyclic loading with steel balls. It was found that resin-modified glass-ionomers were stronger, more flexible, and more resilient than conventional acid-base glass-ionomers. This was in accord with the finding that less marginal breakdown and surface deterioration occurred in a resin-modified glass-ionomer than in a conventional analogue. For some materials the flexural properties progressively improved between 24 hours and 3 months, while others showed no improvement or even deteriorated.

Analysis of Variance↗
PubMed1995

Ten-year longitudinal clinical evaluation of a visible light cured posterior composite resin.

Using modified USPHS criteria, we evaluated annually for ten years 91 cases restored with visible light cured posterior composite resin LFP (Base resin: UDMA; filler: micro crushed type, alumino-silicate, barium glass and silica, 85 wt%, 74 vol%). The 91 cases restored with LFP decreased to 68 in ten years. Of the 23 cases that were lost, one resulted from a pulpal reaction immediately following restoration, four were extracted owing to periodontal disease or extrusion of third molars, two became abutments owing to loss of an adjacent tooth, eight had recurrent caries, and eight were lost owing to caries on a surface having no relationship to the composite resin restoration. Because we observed comparatively little wear, good marginal adaptability, and no discoloration, we concluded that the ten-year clinical success of LFP was on the whole very good, and that this resin has adequate clinical merit as a restorative material for posterior teeth when restricted to restorations covering comparatively small areas.

Adolescent↗
PubMed1995

Effect of immersion in water on linear expansion and strength of three base/liner materials.

The purpose of this study was to characterize three base/liner materials in the initial stage of setting, i.e., dual-cured (light-activated glass ionomer), light-cured (light-activated glass ionomer analogue), and chemically-cured (conventional glass ionomer) materials. Changes in dimension, weight and flexural strength were examined from immediately after setting to the end of one week following immersion in water. The results obtained from these three types of material differed from each other, and showed a statistically significant correlation between changes in dimension and weight. This may be attributed to hygroscopic expansion. They also showed different flexural strength, indicating differences in the polymerization system. From these results, it appeared that marginal gaps following setting would be compensated for by hygroscopic expansion during immersion in water for one day or more. Physical properties would be favourably improved following the setting process which continues to advance during immersion in water.

Absorption↗
PubMed1996

Marginal sealability of resin-modified glass ionomers for base/liner: effect of hygroscopic expansion and bond strength.

The present study investigates the effect of storage in water on hygroscopic expansion and shear bond strength to dentin at periods up to 1 week, of the resin-modified glass ionomers for base/liner, and to analyze the effect on the marginal gaps in dentin cavities. For polishing after storage in water for 1 day, the material indicated significantly smaller marginal gaps both in dentin and in Teflon cavities than in those immediately after light-activation. For the results of after storage in water for 1 day, the material indicated significantly greater bond strength than material immediately after light-activation. The improvement of marginal sealability in dentin cavities may be performed not only by hygroscopic expansion during storage in water but also by greater bond strength after the setting reaction which continues to advance during storage in water.

Analysis of Variance↗
PubMed1999

Cytotoxicity of a trial resin composite liner containing TiK2F6 on rat dental pulp cells.

The aim of this study was to assess the toxicological responses of a resin composite containing TiK2F6 and NaF in rat dental pulp cells. Trial resin composite liners were made, containing 3 wt% fluorides (TiK2F6 or NaF). These specimens were immersed in 5 ml of cell culture medium supplemented at 37 degrees C for 24 hours. The eluates were used for the experiments. We judged the cytotoxicity of the samples by the cell viability. The original elute solution was serially diluted and then the medium was exchanged for the dilute medium. The cell viability at 1, 2 or 5 days after commencement of re-culturing was calculated. The viability of cells in the eluate from the resin composite liners containing TiK2F6 and NaF decreased with time. The cytotoxicity of TiK2F6 was weaker than that of NaF at all times.

Animals↗
PubMed2004

Thermal properties of dental materials--cavity liner and pulp capping agent.

We studied the thermal properties of cavity liners that included calcium phosphate as inorganic filler, in contrast to the conventional pulp capping agents. Therefore, thermal diffusivity, specific heat capacity, and thermal conductivity were measured. In addition, thermal conductivity results were compared with those of restorative materials and human dentin to examine thermal insulation effects. The thermal conductivity of cavity liners ranged from 0.23 to 0.28 W m(-1) K(-1), and that of pulp capping agents ranged from 0.44 to 0.48 W m(-1) K(-1). Test results indicated that the thermal conductivity of cavity liner was lower than those of human dentin, pulp capping agent, cast alloy, and composite resin for restoration, hence suggesting that cavity liner has a good thermal insulation effect.

Acrylic Resins↗
PubMed1989

Dentin adhesive containing 4-META. Effect of a cleanser on bonding.

The effect of the cavity cleanser on the efficacy of the experimental dentin bonding system, which was composed of dentin primer (aqueous solution of 35% hydroxyethyl methacrylate), a dentin bonding agent containing a functional monomer (4-methacryloxyethyl trimellitate anhydride), and an urethane dimethacrylate based composite resin was examined. The bonding efficacy was evaluated by measuring the contraction gap in an experimental cavity which had both an enamel and a dentin cavity margin, and by measuring the tensile bond strength to the flat tooth surface. The whole cavity was cleaned by neutralized 0.5 M EDTA or 10% citric acid containing 3% ferric chloride (10-3 solution) prior to the application of the dentin primer. For the control, the enamel and dentin were etched and cleaned with a 38% phosphoric acid gel and EDTA respectively. It was possible to conclude that the cavity cleanser employing the 10-3 solution for 5s was effective both in cleaning to the dentin and the enamel cavity walls.

Acrylic Resins↗