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At least 19 recordsLinked to original sources

PubMed2003

The effect of an additional flowable compomer layer on microleakage of Class V compomer restorations.

BACKGROUND: Polymerisation shrinkage and the associated stress on composite resins and surrounding structures have been regarded as a major cause of leakage and clinical failures in modern polymer restorations. The purpose of this study was to investigate the effect of an additional flowable compomer layer on the microleakage of Class V dental cavities, which were further filled with a compomer. METHOD: Cavities (32) were prepared in human premolars, conditioned with a non-rinsing agent (Prime & Bond NRC) and treated with the bonding agent (Prime & Bond NT). Sixteen of these cavities were then lined with a layer of flowable compomer (Dyract Flow, approximately 0.5 mm) and further filled with Dyract AP. The other 16 cavities were filled without the flowable compomer. The specimens were thermo-cycled in a 0.5% basic fuchsin solution, sectioned and evaluated for dye penetration using a scoring system of 0 to 4. RESULTS: Lower microleakage values were found at the enamel as well as at the dentine sides when a layer of Dyract Flow was used as a liner. Furthermore, significantly (p < 0.05) lower microleakage was found in enamel than in dentine for both layered and unlayered restorations. CONCLUSION: It can be concluded that a layer of flowable compomer (i.e. Dyract Flow) in a cavity under a compomer may be recommended to improve the marginal seal of a restoration.

Bicuspid↗

PubMed2006

Study of shrinkage-strain and contraction rates of commercial and experimental compomers.

OBJECTIVE: To asses the contraction rate and shrinkage-strain of a new experimental compomer in comparison with four commercial compomers and a flowable composite resin. METHOD: Shrinkage-strain and contraction rate were calculated by measuring the deflection of a disc in a developed instrument using "bonded disk" method. RESULTS: Both shrinkage-strain and contraction rate are reported. Total shrinkage-strain for compomer systems varies from 2.59 to 3.34%, whereas the flowable composite resin showed a value of 3.50%. The contraction rate for compomers varies from 81.60 to 109.80 microm/min, whereas the flowable composite resin obtained 141.6 microm/min. Commercial compomers show a lower contraction rate than the control group, whereas the experimental group only shows statistical differences with a commercial compomer (Dyract AP). SIGNIFICANCE: The shrinkage-strain and contraction rate results for the experimental compomer are as good as those obtained for a commercial flowable compomer and a flowable composite resin. The contraction rates of all compomers could be directly related to polymerization rates. The method used to measure shrinkage-strain and contraction rate is adequate because it simulates conditions in situ. It can be inferred that the contraction rate is directly related to shrinkage-strain.

Bisphenol A-Glycidyl Methacrylate↗

PubMed2002

Light-polymerized compomers: coefficient of thermal expansion and microhardness.

STATEMENT OF PROBLEM: The relationship between the filler content, coefficient of thermal expansion, and microhardness of commercial light-polymerized compomers has not been fully investigated. PURPOSE: This study evaluated the effect of filler content on the coefficient of thermal expansion and microhardness of 3 commercially available light-polymerized compomers. MATERIAL AND METHODS: Five specimens each from 3 commercially available compomers (Compoglass F, Elan and F2000) were evaluated. Linear thermal expansion (microm/ degrees C) was measured with a thermomechanical analyzer in the temperature range 20 degrees to 80 degrees C with increments of 10 degrees C. Standardized specimens were prepared in a metal die (1.5 x 2 x 12 mm) and polymerized for 40 seconds at 700 mW/cm(2) light intensity. The microhardness of 5 specimens from each of 3 compomers were measured with a Vickers hardness tester under a 15-second dwell time and 200-g load conditions. The specimens were polymerized at 700 mW/cm(2) intensity for 40 seconds after placing the compomers into a round aluminum mold. Differences in thermal expansion and microhardness among the compomers evaluated were statistically analyzed by use of one-way analysis of variance at P<.01 significance level, with differences assessed by use of Duncan's multiple range post hoc test. RESULTS: The coefficients of thermal expansion of Compoglass F (54.17 +/- 0.54 microm/ degrees C), Elan (40.94 +/- 0.78 microm/ degrees C) and F2000 (24.43 +/- 89 microm/ degrees C) were almost linear in the temperature range 25 degrees to 80 degrees C for all 3 compomers (r >.99). Inverse correlations between the %wt of filler and the coefficient of thermal expansion (r = -0.98, P<.0001), as well as between the microhardness and the coefficient of thermal expansion (r = -0.98, P<.0001) were observed. On the other hand, a linear correlation between the %wt of filler and microhardness of compomers was exhibited (r = -0.96, P<.0001). The microhardness values for Compoglass F, Elan, and F2000 were 43.82 +/- 1.62, 58.16 +/- 1.90, and 72.94 +/- 3.29, respectively. CONCLUSION: Within the limitations of this study, an inverse correlation between percent weight of filler and coefficient of thermal expansion, and a linear correlation between percent weight of filler and microhardness was observed for the evaluated compomers.

Analysis of Variance↗

PubMed2003

The effect of 30% hydrogen peroxide on the color of compomers.

The interaction between bleaching agents and recently introduced compomers has several issues that need to be explored, including morphology and mechanical properties. To investigate the effect of 30% hydrogen peroxide, a bleaching agent, on the color of compomers, three compomers (Compoglass F, Elan, and F2000) were polymerized, bleached up to 120 h, and then measured to determine the reflectance of the specimen during the bleaching process. Color differences were evaluated from the reflectance and color values that were represented by CIE L*a*b* values. Compomers stored in distilled water were used as a source of reference. Teeth were also used for comparison. Color differences for both the tested teeth and compomers and different periods of bleaching and soaking in distilled water showed statistically significant difference (p < 0.0001). Among the tested compomers, Compoglass F demonstrated the highest color difference. In addition, the color differences were maximal during the first 24 h. After 24 h, the color difference increased nearly linearly. Compomers stored in both a bleaching agent and distilled water did not exhibit much color difference between them. However, the color difference between teeth and compomers was considerable.

Animals↗

PubMed1997

Compomers--a new bracket bonding generation in orthodontics?

Compomers are a new class of materials. With the compomer Dyract Ortho., specifically for bracket bonding, and with Prime & Bond 2.0, a one-component primer for enamel and dentin, DeTrey/Dentsply has developed alternative new materials. The aim of this in vitro study was to test the tensile bonding strength of these materials with different kinds of brackets. Twelve test groups, each with 30 prepared bovine incisors, were formed. Two primers, Prime & Bond 2.0 and PSA, were used. 50% of all teeth were first etched will 36% phosphoric acid. Three types of brackets--metal, ceramic and silan ceramic--were bonded with the compomer Dyract Ortho. For 90 teeth forming a control group, the composite Concise was used. When conditioning the enamel with 36% phosphoric acid, the compomer Dyract Ortho showed a similar tensile bonding strength to the composite Concise. This was not the case if metal brackets were used. Metal brackets had significantly less tensile bonding strength (p < 0.001). The interface of the compomer with the bracket was the main failure site. There was insufficient retention between the compomer and the foil mesh of the bracket base because of the strong consistency of the compomer. Without enamel etching, Dyract Ortho produced an acceptable result only in combination with the primer Prime & Bond 2.0 and silan ceramic brackets. As insufficient data are available to date, the use of compomers in clinical practice cannot yet be recommended.

Animals↗

PubMedDate not supplied

Clinical evaluation of a flowable resin composite and flowable compomer for preventive resin restorations.

This clinical study evaluated the retention and caries protection of a flowable resin composite (Flow Line) and a flowable compomer (Dyract Flow) used in preventive resin restorations as compared to the conventional preventive resin technique which uses a resin composite (Brilliant) and a sealant (Concise). This study observed 205 permanent molars with small carious cavities less than 1.5 mm in width, which were obtained from 165 children aged 7 to 15 years. Flowable resin composite was used to treat 75 teeth, and 71 teeth were treated with flowable compomer in both cavities and caries-free fissures. For the control group, 59 teeth were treated with resin composite in cavities and sealant in caries-free fissures. The teeth were evaluated at 3, 6, 12, 18 and 24-month intervals. After three months, all 205 treated teeth were completely intact. After six months, 66 of the 71 teeth treated with flowable resin composite and 65 of the 70 teeth treated with flowable compomer were complete, compared to 57 of the 58 teeth treated with the conventional preventive resin technique. After 12 months, 60 of the 67 teeth treated with flowable resin composite and 61 of the 67 teeth treated with flowable compomer were complete, compared to 51 of the 55 teeth treated with the conventional preventive resin technique. After 18 months, 53 of the 61 teeth treated with flowable resin composite and 54 of the 62 teeth treated with flowable compomer were complete, compared to 47 of the 53 teeth treated with the conventional preventive resin technique. After 24 months, 49 of the 58 teeth treated with flowable resin composite and 45 of the 57 teeth treated with flowable compomer were complete, compared to 42 of the 52 teeth treated with the conventional preventive resin technique. There were no statistically significant differences in retention rates among all groups after 3, 6, 12, 18 or 24-months (p>0.05). One tooth treated with flowable resin composite and one tooth treated with flowable compomer developed caries after 18 and 24 months, respectively, resulting from partial loss at "caries-free fissures." Five teeth developed caries in the conventional preventive resin group; one after 12 months, two after 18 months and one after 24 months, due to loss at cavities. The final caries occurred after 24 months, resulting from partial loss at "caries-free fissures." The differences in caries development among the three groups were not statistically significant (p>0.05). This study suggested that flowable resin composite and flowable compomer could be used for preventive resin restorations. Meanwhile, a vigilant recall should be followed-up due to the risk of failure for flowable materials in "caries-free" fissures. The repair should be performed immediately, in case the preventive resin restoration develops a fracture or loss.

Adolescent↗

PubMed2004

A preliminary study of experimental polyacid-modified composite resins ('compomers') containing vinyl phosphonic acid.

OBJECTIVES: The aim of this investigation was to determine the properties of two novel compomers formulated with the monomer vinyl phosphonic acid (VPA). The setting properties, mechanical strength, wear characteristics and fluoride release of two experimental unshaded compomers containing VPA were determined, and compared with the commercial compomer Dyract A (shade C3). METHODS: Two novel compomers were prepared, containing, respectively, 0.24% (A) and 2.31% (B) by mass of VPA, and an appropriate amount of reactive glass filler. Their properties were compared with those of Dyract AP (shade A3). Depth of cure was determined according to the method of ISO 4049. Polymerization of model mixtures of bisGMA, TEGDMA and VPA was studied using FT Raman spectroscopy, by comparing the absorption at 1608cm(-1) (aromatic C-C bond) with that at 1313cm(-1) (CC aliphatic). Compressive and biaxial flexure strengths were determined for sets of 6 specimens stored either wet or dry. Wear was determined using a toothbrushing machine and an abrasive slurry, and fluoride release was determined following up to 6 weeks storage in aqueous media, using a fluoride-selective electrode. RESULTS: Of the model monomer mixtures, the one with the greater quantities of VPA showed lowest degrees of polymerization after irradiation for 40s. Compomer A had an acceptable depth of cure, and similar properties to Dyract AP in terms of compressive and biaxial flexure strength, and also fluoride release. Resistance to toothbrush abrasion of both of the experimental compomers was superior to that of Dyract AP. SIGNIFICANCE: These studies demonstrate that VPA can be used as the active monomer in experimental compomers, and is capable of yielding materials with properties equivalent to a commercial material, but with improved resistance to toothpaste abrasion. The level of VPA in the formulation is critical, because this monomer inhibits addition polymerization, hence must be used only in small amounts.

Analysis of Variance↗

PubMed2000

A comparative clinical trial of a compomer and a resin adhesive for orthodontic bonding.

The study aimed to compare the survival time and cariostatic potential of a compomer to that of a resin adhesive when used to bond stainless steel orthodontic brackets to labial segment teeth only. The effect of the patients' sex, age at the start of treatment and presenting malocclusion on bracket survival time was assessed also. Forty-five consecutive patients who attended for fixed appliance therapy were randomly selected. Four hundred twenty-six brackets were bonded (213 with compomer and 213 with resin adhesive) with a split mouth design; the right or left side allocation of compomer in either arch was alternated. Color transparencies of the maxillary incisors, mandibular incisors, or both, and transparencies of the canines, were taken before treatment. At the debond stage, the transparencies were projected (20x) and assessed by an experienced examiner, who used a caries index. The survival time distributions for brackets bonded with each bonding agent were not significantly different (P = .74, paired Prentice-Wilcoxon test; P = .75, Akritas test), with bracket failure rates of 17% and 20% recorded for compomer and resin adhesive, respectively. Neither the patients' sex (P = .85) nor malocclusion (P = .26) appear to affect significantly bracket survival, but patient age was identified as a useful prognostic indicator of bracket survival (P < .001). On average, there was more decalcification related to brackets bonded with resin adhesive than with compomer (P = .0075). Survival time distributions of brackets bonded with compomer or resin adhesive appear comparable, but decalcification was reduced significantly by bonding with compomer.

Adolescent↗

PubMed2002

Enhanced bond strengths of compomers using two dentin bonding systems.

PURPOSE: To measure bond strengths of three commercial compomers using recent dentin bonding systems, and to observe the micromorphology of the cross-sectional interface of the bonded specimens. MATERIALS AND METHODS: One hundred and ten bovine teeth stored frozen were used. The dentin surfaces were ground flat with #600-grit silicon carbide paper, and divided into three groups for bonding: original bonding system group (Xeno Bond/Xeno, Prime&Bond 2.1/Dyract AP, and F2000 Primer/Adhesive/F2000 compomer), Clearfil Liner Bond 2V group (LB 2V/Xeno, LB2V/Dyract AP, LB2V/F2000 compomer, LB2V/AP-X), and Single Bond group (SB/Xeno, SB/Dyract AP, F2000 compomer, SB/Z100). After the bonding procedures had been performed, the bonded assemblies were stored in water for 24 hours at 37 degrees C. Then, tensile bond strengths were measured using a universal testing machine at a crosshead speed of 2 mm/minute. All data were statistically analyzed using one-way ANOVA and Fisher's PLSD at 95% of confidence. Specimens for SEM observations were bonded in the same manner as for the tensile bond test, cut in half, and embedded in epoxy resin. These were then polished to high gloss, gold sputter-coated, and observed with the SEM. RESULTS: Compomers bonded to dentin with recent dentin bonding systems showed significantly higher bond strengths than those with the original bonding systems (P< 0.05). Tensile bond strength of Clearfil Liner Bond 2V was also significantly higher than that of Single Bond (P< 0.05). SEM observations showed good interaction between the compomers, adhesive systems, and dentin with any restorative material used. For Xeno Bond/Xeno, Prime & Bond 2.1/Dyract AP, and Primer/Adhesive/F2000 compomer, the thicknesses of the hybrid layer were approximately 0.8-1.1 microm, 0.3-0.5 microm, and 0.7-1.5 microm respectively. On the other hand, the hybrid layer produced by LB2V was approximately 0.5 to 1.0 microm, whereas for SB was approximately 3.1 to 4.1 microm thick. The thickness of the hybrid layers created in each bonded sample depended on the adhesive material used.

Analysis of Variance↗

PubMed1998

Fluoride release from glass-ionomer and compomer restorative materials: 6-month data.

OBJECTIVES: To investigate the daily fluoride release of two glass ionomers (Ketac-Fil and ChemFil Superior) and two compomers (Compoglass and Dyract Restorative) over 6 months. METHODS: A pilot study evaluated the time taken for sample solutions to equilibrate to establish an appropriate time period for sample solution storage between fluoride ion measurements. In the main study storage water replacement and fluoride ion determination was made daily using a specific ion electrode, TISAB buffer and standard solutions for calibration. RESULTS: Equilibration of fluoride concentration in aqueous solution occurred in under 48 h for all materials. Total fluoride released (microgram mm-2) after 6 months by Ketac-Fil (30.6, s.d. 4.9) was significantly greater than ChemFil Superior (12.7, s.d. 2.5), Compoglass (10.4, s.d. 1.0) and Dyract Restorative (7.7, s.d. 1.7) (P < 0.05). Daily fluoride release at 24 h and 10 days was significantly higher for the glass ionomers than the compomers (P < 0.05). After 40 days the daily fluoride release (microgram mm-2) from ChemFil Superior (0.05, s.d. 0.01) was not significantly different from Compoglass (0.04, s.d. 0.01) and Dyract Restorative (0.03, s.d. 0.00) (P > 0.05). Daily fluoride release from Ketac-Fil remains significantly higher than the compomers at 3 and 6 months (P < 0.05). CONCLUSIONS: Specimens stored in water equilibrate rapidly, suggesting the rate at which storage water is changed may alter the relative fluoride release rates of materials. This important fact is often overlooked. Fluoride release from the glass ionomers is initially higher than for the compomers. Fluoride release from glass ionomers falls rapidly to approach levels released by compomers. Compomers produce no initial burst of fluoride and levels of release remain relatively constant.

Aluminum Silicates↗

PubMed1999

Esthetic compomer restorations in posterior teeth using a new all-in-one adhesive: case presentation.

UNLABELLED: Compomers have continually gained in importance since their introduction in 1993, especially because of their ease of handling. The main indications are cervical lesions, Class III restorations, and restorations in the primary dentition. To extend the indications of compomers to esthetic Class I and II restorations in the permanent dentition, improvements in wear resistance and bond strength need to be accomplished. Studies have shown an improved bond strength and less marginal gap formation between compomers and enamel and dentin with acid etching of the tooth before application of conventional mild self-etching adhesives. Newly formulated, improved self-etching adhesives with a higher demineralization potential recently have been developed. The objective of this case presentation is to demonstrate step-by-step the clinical procedure for the application of a newly developed self-etching adhesive with high demineralization potential in combination with a compomer material in occlusal cavities. CLINICAL SIGNIFICANCE: Improved self-etching adhesives provide a faster and simplified application technique and allow effective conditioning and priming of enamel and dentin in one step, without waiving sufficient bond strengths. With limited indications, compomers are used in combination with these self-etching primers to restore occlusal cavities in posterior teeth. Evidence-based dentistry requires exact scientific data to evaluate whether this new trend results in benefits for patients. However, until clear evidence from controlled clinical studies supports the use of improved compomer systems in Class I and II cavities in the permanent dentition, dentists should be careful with this indication.

Bicuspid↗

PubMed2000

In vitro study of enamel and dentin marginal integrity of composite and compomer restorations placed in primary teeth after diamond or Er:YAG laser cavity preparation.

PURPOSE: The aim of this in vitro study was to evaluate the effect of laser vs diamond instruments on Class II and Class V cavity margins in primary teeth with SEM after restoration with composite and compomer materials and subsequent thermocycling. MATERIALS AND METHODS: Class V cavities with margins completely located in enamel were prepared in 36 extracted primary teeth to examine the restoration-enamel interface. Eighteen cavities were prepared with an Er:YAG laser operated at 3 Hz, 300 mJ/pulse, and 18 with a spherical fine diamond bur. In 24 primary teeth, Class II cavities with cervical proximal margins located in dentin were prepared for examination of the restoration-dentin interface. All Class II cavities were prepared with a conventional cylindrical diamond bur. In 12 cavities, the margins located in dentin were conditioned with an Er:YAG laser (1 Hz, 100 mJ/pulse). All cavities were restored with a fine hybrid composite resin or a compomer material. RESULTS: SEM examination of Class V cavities after thermocycling (between 5 degrees C and 55 degrees C, 2500 cycles) revealed over 90% "perfect" margins in all composite fillings and in those compomer restorations applied after conventional preparation and acid etching. Compomer restorations placed without acid etching revealed a significantly superior marginal integrity in laser-prepared cavities (81% perfect margins) vs conventionally prepared cavities (60% perfect margins). SEM analysis of the dentinal margins of both compomer and composite restorations in Class II cavities showed mean percentages of perfect marginal adaptation ranging from only 13% to 66%. CONCLUSION: Er:YAG laser treatment can be recommended for composite restorations in Class V cavities in primary teeth. Compomer restorations can be placed after conventional preparation of Class V cavities and acid etching or after laser preparation. Dentin bonding in Class II cavities in primary teeth is not sufficient and cannot be improved with Er:YAG laser pretreatment.

Acid Etching, Dental↗

PubMed2002

Marginal seal of sealant and compomer materials with and without enameloplasty.

OBJECTIVES: This in vitro study evaluated the quality of marginal seal and fissure penetration of a resin-sealant (Concise) and a compomer restorative material (F2000) with and without enameloplasty. SAMPLE AND DESIGN: Thirty extracted sound human permanent third molar teeth were divided into six groups of five and used in this in vitro study. METHODS: Occlusal surfaces of the teeth in different groups were either left intact or prepared using a #582 S diamond bur. Teeth were then restored with Concise and F2000 restorative materials using combinations of different surface treatments. Teeth were prepared for microleakage, then immersed in 5% methylene blue for 4 h, and subsequently sectioned into four bucco-lingual sections. Sections (20 per group) were examined using a stereomicroscope. The following parameters were evaluated: marginal leakage, marginal gap, voids and filling defects, as well as enamel fissure penetration. RESULTS: Kruskal-Wallis one-way ANOVA showed statistically significant differences between the groups for marginal leakage (P < 0.0001), marginal gap (P < 0.001), and enamel fissure penetration (P < 0.001). No statistically significant differences between the groups for voids and filling defects were detected. Non-parametric Tukey's multiple range test showed that microleakage of sealant with acid etch and tooth preparation and compomer with acid etch, bonding agent and tooth preparation were statistically significantly less than that of compomer with bonding agent and no tooth preparation (P < 0.0001) and compomer with bonding agent and tooth preparation (P < 0.01). CONCLUSIONS: Microleakage is similar when sealant with acid etching, and compomer with acid etching and bonding agent, are used with and without enameloplasty. Marginal gap is more evident in the compomer group with bonding agent and without enameloplasty. Enamel fissure penetration is better when enameloplasty and acid etching are used.

Acid Etching, Dental↗

PubMedDate not supplied

Fracture resistance of compomer and composite restoratives.

This study evaluated and compared the fracture toughness of compomers and composites. Three compomer (Compoglass F [CG], Vivadent; F2000 [FT], 3M-ESPE; Dyract Posterior [DP], Dentsply) and three composite (Tetric Ceram [TC], Vivadent; Z250 [ZT], 3M-ESPE; Esthet X [EX], Dentsply) restoratives were selected for the study. Single-edged notched specimens (25 x 2 x 2 mm) were fabricated according to manufacturers' instructions and conditioned in distilled water at 37 degrees C for one week prior to testing. Seven specimens were made for each material. The specimens were loaded to failure using an Instron microtester with a crosshead speed of 0.5 mm/minute. Data were subjected to ANOVA/Scheffe's test and Independent Samples T-test at significance level 0.05. The mean fracture toughness (K(IC)) ranged from 0.97 to 1.23 MPam 1/2 for compomers and 1.75 to 1.92 MPam 1/2 for composites. The fracture toughness of compomers was significantly lower than their composite counterparts. No significant difference in K(IC) values was observed among the different composites. When the compomers were compared, FT had significantly higher fracture toughness than DP and CG. In view of their poorer resistance to crack propagation, compomers are not recommended for use in stress-bearing areas.

Analysis of Variance↗

PubMedDate not supplied

Biocompatability of compomer restorative systems on nonexposed dental pulps of primate teeth.

This study evaluated the histologic response of total-etched and nonetched compomer restored cavity preparations. One hundred fifteen class 5 cavity preparations were placed in the teeth of four healthy adult monkeys at 7, 27, and 90 days. A 37% H3PO4 was applied for 10 seconds and rinsed in total-etched preparations. No statistical differences were seen in inflammatory reactions among total-etched or nonetched compomers at 7, 27, and 90 days. There were no statistical differences in inflammatory cell responses among all compomer systems in regard to time intervals. Pulpal responses of compomers were greater than IRM at each time period. Pulp responses were associated with stained bacteria in 32 of 89 compomer teeth. No necrotic pulps were seen in any teeth. Statistical data show a positive correlation (P < 0.05) between bacterial presence and pulpal inflammation. IRM pulps showed no inflammation or bacterial staining. Compomers are biologically compatible with pulp tissues when bacteria are excluded.

Acid Etching, Dental↗

PubMed2001

Long-term effects of four extraction media on the fluoride release from four polyacid-modified composite resins (compomers) and one resin-modified glass-ionomer cement.

It was the aim of the present experiments to evaluate the fluoride leaching of four compomers and one resin-modified glass-ionomer cement (gic) into aqueous media over a 1-year period. Various extraction/equilibrium solutions were applied to simulate important intraoral parameters. Specimens of Dyract, Compoglass F, F2000, one experimental compomer, and the resin-modified gic Fuji II LC were stored for 366 days in distilled water (I), acidic medium (pH 4.2) (II), neutral medium (pH 7.0) (III), or solution III supplemented with 1.6 u/mL porcine liver esterase (IV). Equilibrium media were changed and fluoride concentration was measured every 48 h (first 30 d), thereafter each week (twice), then every 14 d (three times), and finally every 28 d up to a total period of 1 year. Data were statistically analyzed for significant differences by means of Scheffe' tests (p < 0.05). The gic and the compomers leached significantly more fluoride into the acidic solution in the initial phase compared to the other media (p < 0.05). Cumulative fluoride release from all materials (except experimental compomer) was elevated because of esterase activity (p <0.05). Measurable but low quantities of fluoride were segregated into all media during the 1-year period. But no significantly different long-term fluoride release into the various media from the investigated materials was found. The data indicate that plaque-associated organic acids or salivary hydrolases may increase initial fluoride release from resin-modified gics or compomers in the oral cavity. Because long-term fluoride release from all materials decreased to low concentrations within a 30-day period, their caries preventive effect remains questionable.

Animals↗

PubMed2001

Effects of various storage media on surface hardness and structure of four polyacid-modified composite resins ("compomers").

It was the purpose of this study to determine surface microhardness and structure of four poly-acid modified composite resins ("compomers") after 1-year storage in water and various solutions. Specimens of the compomers Dyract (DY), Compoglass F (CG), an experimental compomer (EC), and of F2000 (F) were stored at 37 degrees C for 1 year in distilled water, acidic buffer (pH 4.2), neutral buffer (pH 7.0), and neutral buffer supplemented with 1.6 u/ml porcine liver esterase. Then the specimens were kept dry for 3 days further. Continuously dry-stored samples (37 degrees C) served as controls. Surface microhardness (Vickers) was read at baseline (prior to wet storage), after 24 h and 144 h, then every 30 days up to 1 year and after the further 3 days of dry storage. Surface roughness (Ra) was determined at baseline, after 3, 6, 9, and 12 months and, finally, after the further 3 days. In addition, randomly selected control and experimental specimens were investigated by SEM. Data were statistically analyzed by a three-factor ANOVA using Scheffé tests (P<0.05). Vickers hardness of all experimental samples dropped significantly due to wet storage (P<0.000) during the first month. However, the type of storage medium did not influence microhardness significantly. Surface roughness was not altered by wet storage except for compomer F, which revealed pronounced surface cracks in the SEM. Altogether, our findings point out that surface microhardness and structure of the investigated compomers were not significantly deteriorated by the tested intraoral conditions, such as humidity, pH-fluctuation, or the action of hydrolytic salivary enzymes.

Acids↗

PubMed2001

Effect of enamel pretreatments on bond strength of compomer.

OBJECTIVES: The objective of this study was to evaluate the effect of various enamel surface treatments on the bond strength of a compomer to enamel. METHODS: Ground bovine enamel specimens were divided into four groups. A compomer (F2000, 3M) was bonded to the specimens using different enamel surface treatments. Two groups examined the effect of application of the F2000 self-etching primer/adhesive (3M) with respect to static or dynamic priming. A third examined use of the primer/adhesive after phosphoric acid etching, and the fourth (control) group provided bond strength of the compomer to phosphoric acid etched enamel with a resin bonding system (Single Bond, 3M). Shear bond strengths for the specimens were measured after 24h storage in water at 37 degrees C. Effects of the various surface treatments on enamel were examined by SEM. RESULTS: Significant differences in bond strength of compomer to enamel were found that were related to the various surface pretreatments. Dynamic priming resulted in higher enamel bond strengths than static priming, and the best bond strengths were obtained when the enamel was etched with phosphoric acid. SEM analysis showed that depth of etch and resin penetration was also directly related to the bond strengths measured. SIGNIFICANCE: Bond strength of compomer to enamel is significantly affected by the method of pretreatment of the enamel.

Acid Etching, Dental↗