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PubMedDate not supplied

A comparison of the bond strength to enamel and dentin of two compomers: an in vitro study.

The aim of this study was to evaluate the bond strength of two resin-reinforced glass ionomer cements to etched and unetched enamel and to dentin. Thirty-six noncarious human premolar teeth were used. Flat buccal and lingual surfaces were prepared. Dyract and Compoglass were used. The teeth were distributed at random into six groups of six teeth each. The materials were handled according to manufacturers' instructions. In groups 1 and 3 the enamel was etched with 37 percent phosphoric acid. All samples were sheared with an Autograph AG5 machine at a crosshead speed of 0.5 mm/min. Two way ANOVA and comparison with the Tukey test were used to evaluate the results. These showed that on etched enamel Dyract had a significantly higher bond strength (p = 0.02); on unetched enamel Compoglass had a statistically higher bond strength (p = 0.003), and on dentin the materials provided the same bond strength. Overall, disregarding surfaces, there was no difference between the two materials.

Acid Etching, Dental↗
PubMedDate not supplied

Clinical evaluation of a polyacid-modified resin composite (compomer).

The purpose of this study was to evaluate the clinical performance over 1 year of the proprietary polyacid-modified composite resin Dyract (DeTrey Dentsply). Forty-one restorations (five in interproximal anterior cavities, 36 in noncarious cervical cavities) were placed following the manufacturer's instructions. After 1 year, one of the cervical restorations had been lost, and eight restorations showed some degree of marginal discoloration. Overall, Dyract showed mixed results as a tooth-colored restorative material in nonstress-bearing areas. The long-term clinical performance and reasons for incipient marginal discoloration need further investigation.

Aged↗
PubMed2003

The effect of saliva on surface hardness and water sorption of glass-ionomers and "compomers".

A study is reported in which commercial dental materials (glass-ionomers, resin-modified glass-ionomer and polyacid-modified composite resins) in the form of discs of dimensions 6 mm diameter x 1 mm thickness were prepared and exposed to natural salivas (parotid and unstimulated whole), artificial saliva and water for up to 1 year. Surface hardness was measured at various time intervals, and water sorption characteristics were determined. For all types of material, storage in artificial saliva gave specimens of lowest surface hardness by amounts that were generally significant to p<0.05, whereas no differences were found between specimens stored in water or either of the natural salivas. Water sorption characteristics were found to be unaffected by the nature of the storage medium. These results contrast with some previous findings and were not expected, given the known surface reactions between salivas and glass-ionomers, or the known enzymic degradation of composite resins. They demonstrate, however, that the current widespread practise of employing pure water for storage of specimens in laboratory studies is acceptable.

Journal Article↗
PubMedDate not supplied

Bond strength of a resin composite to a polyacid-modified resin composite under different conditions.

OBJECTIVE: The aim of this in vitro study was to evaluate the tensile bond strength values between polyacid-modified resin composite ("compomer") and resin composite materials under different conditions. METHOD AND MATERIALS: There were five experimental groups in the study. In group A, resin composite was placed directly on polyacid-modified resin composite surfaces. In group B, bonding agent was applied to polyacid-modified resin composite surfaces and then resin composite was placed on the compomer. In group C, compomer specimens were stored for 1 week and then resin composite was placed directly on these aged compomers. In group D, compomer specimens were again stored for 1 week, and then the bonding agent and resin composite were applied to the compomer surfaces. In group E, the surfaces of aged (1 week) compomers were roughened before the bonding agent was applied and the resin composite was placed on the prepared surfaces. A statistical analysis of the results was made with the Kruskal-Wallis test method. RESULTS: The mean tensile strength values of the groups were as follows: group A = 12.84 MPa; group B = 15.03 MPa; group C = 10.60 MPa; group D = 11.56 MPa; group E = 24.87 MPa. There were statistically significant differences between groups E and A; groups E and C; groups E and D; and groups C and B. CONCLUSION: Mechanical roughening of a polyacid-modified resin composite surface was found to be the most effective factor in increasing the tensile bond strength between an aged compomer and a resin composite.

Compomers↗
PubMed2002

Effect of bleaching agents on the fluoride release and microhardness of dental materials.

The use of bleaching agents has become a popular procedure for whitening teeth. Recently introduced polyacid-modified composite resins (compomers) have several favorable features, such as improved physical properties and fluoride release. Because these two materials have many possibilities to interact in the oral cavity during dental treatment, it is necessary to understand such interaction. To evaluate the effect of a bleaching agent on dental restoratives, three compomers were photopolymerized and then bleached for 1, 2, 3 and 5 days with the use of 30% hydrogen peroxide. Fluoride release, surface microhardness, and surface modifications were evaluated. It was found that the cumulative fluoride release was found to be linearly correlated to the tested periods of bleaching in all compomers. Among the tested compomers, F2000 showed the highest cumulative fluoride release. Bleached compomers became soft because of surface degradation, so the surface microhardness decreased. F2000 showed an apparent crack formation that was not observed in other compomers. The nearly linear correlation between the filler content and microhardness was found in the control samples. However, the same correlation was not observed after the compomers were stored in a bleaching agent or distilled water.

Compomers↗
PubMed1999

Influence of light irradiation on the volumetric change of polyacid-modified resin composites.

OBJECTIVES: Recently, a new restorative material called a 'compomer', which is classified as a polyacid-modified resin composite, has become available. The volumetric shrinkage of compomers may create marginal gaps that influence the bonding ability and longevity of a restoration. Since compomers have been introduced recently, their volumetric change during curing is not fully understood. The purpose of this study was to evaluate the volumetric change of compomers. METHODS: Three compomers, Compoglass (Vivadent), Dyract (Dentsply), and Ionosit Fil (DMG) were employed. The material was placed into a Teflon mould, 4 mm in diameter and 2 mm height, and extruded into the dilatometer. Then the specimens were light activated and the change in the height of the meniscus of water was recorded using a CCD camera and VRC. RESULTS: The average volumetric shrinkages of the compomers after 160 s were 2.4% for Compoglass, 2.7% for Dyract, and 2.1% for Ionosit-Fil. For all materials tested, there was a tendency of increasing volumetric shrinkage with increased irradiation time. CONCLUSIONS: The results of this study indicate that the volumetric change of compomer is influenced by the duration of light exposure, light intensity, and environmental conditions to which the materials are exposed.

Chemical Phenomena↗
PubMed2006

Clinical performance of pulpotomized primary molars restored with resin-based materials. 24-month results.

PURPOSE: To evaluate the clinical and radiographic success rates of pulpotomized (formocresol) primary molar teeth restored with a resin-based composite (TPH) or a polyacid-modified resin composite (Dyract AP) over a 2-year period. METHODS: 100 composite and 100 compomer restorations were placed over pulpotomized teeth by two clinicians in 84 patients. Two other calibrated clinicians evaluated the restorations using the modified USPHS/Ryge criteria observing the following characteristics: marginal discoloration, marginal adaptation, wear/anatomic form, enamel loss and caries. Mann Whitney U test, Friedman test and Wilcoxon signed ranks tests were used for statistical analysis (P= 0.05). RESULTS: At 24 months, 80 composite and 72 compomer restorations were available for evaluations. Except for baseline, compomer restorations showed significantly more marginal discoloration (P= 0.001) and marginal disintegrity (P= 0.001) than did the resin composite. Compomer restorations demonstrated a significant increase in minor enamel cracks along restoration margins over time (P= 0.001), but no chipping or loss of enamel was detected. Caries was observed only in 2.8% of compomer restorations and was restricted to restoration margins. 2% of composite and 17% of compomer restoration-treated teeth were extracted due to radiographic evidence of failure. Pathological root resorption patterns observed beneath failed compomer restorations were strongly suggestive of coronal microleakage.

Child↗
PubMed2004

FTIR investigation of monomer polymerisation and polyacid neutralisation kinetics and mechanisms in various aesthetic dental restorative materials.

Diamond ATR FTIR has been used to quantify light catalysed polymerisation and polyacid neutralisation rates in various glass ionomer cements (GIC), resin-modified GICs (RMGIC) and compomers. At 150s after the start of light exposure, levels of methacrylate polymerisation on the lower surfaces of 1mm thick specimens were 97% and 98% for the RMGIC, Vitremer and Fuji II LC and 47% and 37% for the compomers, Compoglass and Dyract. After light exposure, polymerisation rates for the compomers decreased linearly with inverse time. By 50,000s Compoglass and Dyract were 62% and 51% polymerised. Initial rate of polyacid neutralisation in the GIC Shofu HIFI was 0.32 times that of Fuji IX GIC. Those in Vitremer, Fuji II LC, Compoglass and Dyract were 0.16, 0.09, 0.004 and 0.004 times that of Fuji IX. Excluding short initial periods, log of neutralisation rates decreased linearly with log-time. Average gradients were -1.35 for the GIC, -0.80 for the RMGIC and -0.59 for the compomers. By 50,000s, polyacid salt concentrations for the RMGIC and compomers were 0.41 and 0.016 times that of the GIC. Reaction mechanisms have been discussed and used to help interpret material mechanical properties, fluoride release rates and adhesion to tooth structure.

Compomers↗
PubMed2001

Inhibition of bacterial and glucan adherence to various light-cured fluoride-releasing restorative materials.

OBJECTIVES: This study investigated the potential plaque adhesion properties of various light-cured fluoride-releasing restorative materials by measuring the amount of adhering radiolabeled bacteria and glucan. METHODS: Three resin-modified glass ionomer cements (RMGI) and two polyacid-modified resin composites (compomer) were used in this study. As a control, one light-cured resin composite was added. Disk-shaped specimens were made following the manufacturers' recommendations and the respective surfaces were finished with a 600-grit abrasive paper. Streptococcus sobrinus B13 was selected as a cariogenic bacterial strain. The amount of bacteria and glucan adhered to these specimens were measured after 3, 8 and 24h incubations with radiolabeled cariogenic bacteria and sucrose. RESULTS: After 3 and 8h incubations, the amount of adhered bacteria and glucan was small and there were no significant differences among the restorative materials except in the resin composite. Although after 24h incubation the amounts of adhered bacteria and glucan, significantly increased on the RMGIs and compomers, these were still significantly less than the resin composite except one compomer. Although at 3h no good correlation was found between the contact angles and the amount of bacteria and glucans, the correlation coefficients were high at 8 or 24h. In addition, the coefficients for bacteria were always higher than those for glucan irrespective of the incubation times. CONCLUSIONS: After 24h resin-modified glass ionomer cements and compomers showed significantly smaller amounts of adhered bacteria and glucans compared to resin composite with an exception of glucan adherence on one compomer.

Acrylic Resins↗
PubMed1999

Comparison of shear bond strength of three bonding agents with metal and ceramic brackets.

Shear bond strengths of a light-cured composite resin, a light-cured glass ionomer cement, and a light-cured compomer used with metal and ceramic brackets were compared, and ARI scores were evaluated. Ceramic brackets showed statistically higher shear bond strengths than metal brackets when bonded with all test materials (p<0.001). When used with metal brackets, the light-cured glass ionomer cement (LCGIC) and compomer materials demonstrated statistically lower shear bond strengths than the light-cured composite (p<0.01 and p<0.001, respectively). When used with ceramic brackets, LCGIC was found to have significantly lower shear bond strength than the composite material (p<0.001). Despite its relatively low shear bond strength, LCGIC demonstrated optimal bonding values (8.39+/-3.24 MPa) with ceramic brackets. Bond failures within the LCGIC groups occurred at the adhesive-tooth interface, whereas in the compomer and composite groups, failures were detected at the adhesive-bracket interface. In the metal bracket group, clinically acceptable shear bond strength was obtained only with the composite resin (7.06+/-1.65 MPa). Compomer and LCGIC demonstrated values well below the accepted standard for metal brackets (4.32+/-1.75 MPa and 4.45+/-1.06, respectively), while in the ceramic bracket group, values for composite and compomer were above the desired level (14.40+/-5.88 MPa and 12.31+/-6.09, respectively). LCGIC showed reasonably good bond strength with ceramic brackets, suggesting that this material may be considered suitable for use with ceramic brackets in clinical situations where moisture cannot be controlled.

Acrylic Resins↗
PubMed2007

Three cements used for orthodontic banding of porcelain molars.

OBJECTIVE: Objectives of this study were to (1) compare the mean shear-peel bond strength of orthodontic bands luted to porcelain molar denture teeth with glass ionomer cement (GIC), resin-modified glass ionomer cement (RMGIC), or compomer cement; (2) assess the amount of cement remaining on the teeth after debanding; and (3) compare the survival times of the cemented bands subject to mechanical fatigue. MATERIALS AND METHODS: Sixty banded denture teeth (20 per cement group) were used to determine shear-peel bond strength, and 30 banded denture teeth (10 per cement group) were used to determine fatigue survival time. Shear-peel bond strength was determined with a universal testing machine, and groups were compared by one-way analysis of variance. The amount of cement remaining on the teeth after band removal was scored, and a chi-square test was used to compare groups. Fatigue testing was conducted in a ball mill, and a log-rank test was used to compare differences in survival times. RESULTS: No differences were found in mean shear-peel bond strength among the three groups. The amount of cement remaining on the teeth varied between the compomer and GIC groups (P = .01), with more compomer cement remaining relative to GIC. The mean survival times of bands cemented with compomer or RMGIC were longer than for bands cemented with GIC (P < .001). CONCLUSION: The findings show that on porcelain teeth the band cements have comparable mean shear-peel bond strengths, but that band retention with RMGIC and compomer cement are superior to GIC when subjected to simulated mechanical fatigue.

Analysis of Variance↗
PubMed2000

Effect of conditioner and restorative resin on enamel bond strengths.

PURPOSE: To evaluate the effect of three enamel conditioners and four restorative materials on enamel shear bond strengths. MATERIALS AND METHODS: 120 bovine incisors were polished to 600-grit and randomly assigned to three enamel adhesive systems (n=40): Syntac Single Component with phosphoric acid etching (PA-SSC), Syntac Single Component without phosphoric acid etching (SSC), and Experimental Prompt L-Pop (LPI), a self-etching adhesive. The specimens were restored with one of four resin restorative materials (n=10): (1) Compoglass F, a high-viscosity compomer; (2) Compoglass Flow, a low-viscosity compomer; (3) Tetric Ceram, a high-viscosity resin-based composite (RBC); and (4) Tetric Flow, a low-viscosity RBC. After thermocycling, shear tests were carried out with an Instron Universal Testing Machine. Mean enamel bond strengths were analyzed with ANOVA and Duncan post hoc test at P < or = 0.05. RESULTS: PA-SSC resulted in higher mean bond strengths than LP1, but the difference was not statistically significant. Both PA-SSC and LP1 resulted in statistically higher mean bond strengths than SSC at P < or = 0.0001. The lowest mean bond strengths of all the groups were obtained when SSC was used with an RBC (Tetric Ceram or Tetric Flow). SSC and PA-SSC resulted in statistically higher mean bond strengths when used with a compomer than when used with an RBC, regardless of the viscosity. Although recommended to be used only with compomers, LP1 resulted in statistically similar enamel bond strengths when used with the composite of corresponding viscosity (Tetric Ceram vs. Compoglass F; Tetric Flow vs. Compoglass Flow). LP1, however, resulted in higher enamel bond strengths when combined with Tetric Ceram than when combined with Tetric Flow. When the results were pooled for "viscosity", high-viscosity restorative materials resulted in higher bond strengths than low-viscosity materials at P < or = 0.041. When the data were pooled for "restorative material", compomers resulted in higher bond strengths than composites at P < or = 0.0001.

Acid Etching, Dental↗
PubMed2002

Microleakage and wall adaptation of conservative restorations.

PURPOSE: To evaluate the microleakage and wall adaptation of different restorative materials in sealed and unsealed conservative restorations after storage in an acid environment. MATERIALS AND METHODS: 100 conservative cavity preparations were prepared in the occlusal surface of 50 non-carious, extracted human permanent molar teeth. The teeth were divided into 5 groups and restored with either flowable compomer, compomer, amalgam, resin-based composite or non-bonded resin-based composite (control). One half of the restorations in each group was sealed with a light cured unfilled sealant material, while the other half was left unsealed. The teeth were placed in artificial saliva for 30 days, radiographed, thermocycled 500 times, placed in an artificial caries solution, immersed in dye, sectioned three times, and recorded at x60 magnification. Three independent examiners assessed each of the 300 recorded sections for leakage and assessed each radiograph for wall adaptation using a slide projector. Kruskal Wallis and Mann-Whitney nonparametric tests were used to analyze the results. RESULTS: Sealed restorations showed significantly less leakage than unsealed (P < 0.001). Of the sealed groups, amalgam showed less leakage than flowable compomer (P = 0.027). Of the unsealed groups, flowable compomer showed less leakage than both composite groups (P = 0.032 and P = 0.045). Radiographically, the two compomer groups and the amalgam group had fewer adaptation voids than both composite groups (P < 0.001).

Bisphenol A-Glycidyl Methacrylate↗
PubMed1998

Fluoride release from tooth-colored restorative materials: a 12-month report.

BACKGROUND: This study measured the amount of fluoride released from three light-activated glass polyalkenoate (ionomer) cements, a conventional glass polyalkenoate, a compomer and a fluoridated composite over a period of 12 months. METHODS: Five discs (7 x 2 mm) of each material were sequentially immersed in 4 mL portions of deionized water at 37 degrees C and before each measurement, the test specimen was rinsed with 1 mL of deionised water. An Orion Model 901 microprocessor digital Ionalyzer was used for the measurements and the data obtained were converted into microgram/cm2. The amount of fluoride released was measured 86 times during the 12-month test period. RESULTS: It was found that the pattern of fluoride release from the light-activated glass polyalkenoates was similar to that of the conventional glass polyalkenoate. The light-activated glass polyalkenoates, however, released significantly more fluoride than the conventional material. The composite and the compomer released significantly less fluoride than any glass polyalkenoate tested and the difference between the composite and the compomer was not significant. CONCLUSION: It was concluded that the light-activated glass polyalkenoates tested released more fluoride than a conventional glass polyalkenoate, a compomer or a composite, and that with regard to fluoride release the compomer behaved more or less like the composite.

Color↗
PubMed1998

Bonding mechanism of Compoglass to dentin in primary teeth.

This study evaluated the bonding mechanism of Compoglass compomer to dentin in primary teeth. Buccal or labial dentinal surfaces of 20 human extracted, non carious primary teeth stored in 4 degrees C physiological saline solution were obtained by grinding on silicon carbide paper (final grit 600). The specimens were divided into two groups of 10 teeth each: (1) unetched dentin, Compoglass SCA, Compoglass; and (2) dentin etched with 10% phosphoric acid (Etch-AII), Compoglass SCA, Compoglass. The Compoglass SCA and Compoglass compomer were placed according to the instructions of the manufacturer, except Group 2 were the dentin was first etched with 10% phosphoric acid for 30 seconds. Twenty-four hours after placing the compomer over the treated dentinal surface, the specimens were dehydrated with a series of alcohol and freon. Then critically point dried. The specimens were split with a chisel and the compomer/dentin interface evaluation was performed with the SEM. The results showed that when the instructions of the manufacturer were followed (Group 1) the compomer showed a very close relation to the dentin with some tag structures penetrating the dentin. When phosphoric acid etching preceded the compomer placement a hybrid layer with tags penetrating the dentin was noted in most specimens.

Acid Etching, Dental↗