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PubMedDate not supplied

Sealing and dentin bond strengths of adhesive systems.

The objectives of this research were (1) to analyze the variations of the permeability of dentin after restoration with two polyacid-modified resin composites (Compoglass, Dyract) and four single-bottle adhesives (Prime & Bond 2.0, Syntac Single Component, OptiBond Solo, and Single Bond--Scotch Bond 1 in Europe--immediately (approximately 1 hour) after insertion. A perfusion system with distilled water was used at a pressure of 32.5 cm of water; (2) to study the bond strength of their interfaces; and (3) to find the correlation, if any, between both parameters. None of the materials used produced a complete cessation in fluid filtration. Tensile bond strengths were very low (maximum: P&B = 3.96 MPa) probably because of the very large bonding surfaces used (mean bonded surface area = 88.8 mm2). No significant correlation was found between tensile bond strength and the sealing ability for any material.

Absorption↗
PubMedDate not supplied

Polymerization color changes of esthetic restoratives.

The color changes of three different types of tooth-colored restoratives during polymerization were investigated using colorimetry. L*, a*, b* color parameters of five different shades of Z100 (a mini-filled composite resin), Fuji II LC (a resin-modified glass-ionomer cement), and Dyract (a polyacid-modified composite resin) were taken precure and postcure. The results showed that the restoratives evaluated all underwent color changes during polymerization. The polymerization changes in color parameters were shade and not material dependent. Changes in L* parameter or lightness during polymerization were significant for all material and shade combinations and had the greatest influence on the overall polymerization color change. As the color change was perceivable by the human eye for most shades of materials, the clinical practice of polymerizing some material on, or adjacent to, the undried tooth to confirm shades of esthetic restoratives before restorative procedures is prudent.

Colorimetry↗
PubMedDate not supplied

Effects of aging on repair bond strengths of a polyacid-modified composite resin.

The effect of age of a poly-acid-modified composite resin on repair bond strength after different methods of surface conditioning was studied. Surface conditioning methods included the following: maleic acid with resin application; polyacrylic acid with resin application; sand-blasting with resin application. Shear bond testing between the aged and new material was carried out with an Instron Universal Testing Machine. Although repair bonds strengths after all surface conditioning methods were significantly higher than the control group at 1 week, no statistically significant differences in bond strengths were noted after aging the material for 6 months. After all aging periods, surface conditioning with sand-blasting and resin application resulted in the highest repair bond for poly-acid-modified composite resins. Specimens with cohesive failure in the material gave significantly higher repair bond strengths than specimens with adhesive failure at the repaired interface.

Analysis of Variance↗
PubMed1999

Bonding amalgam to a resin-modified glass-ionomer base.

PURPOSE: To determine which surface treatment of a resin-modified glass-ionomer (RMGI) will result in optimal bond strength to amalgam when used with an amalgam adhesive. MATERIALS AND METHODS: Fifty discs of Fuji II LC (4 mm thick) were cured in acrylic testing holders and randomly divided into 5 groups of 10 each. The surface of the glass-ionomer was treated in 1 of 5 ways: (1) no treatment (control) (2) no etch, Amalgambond (AB) primer and AB adhesive (3) citric acid etch, AB primer, and AB adhesive (per manufacturer's instructions) (4) 37.5% phosphoric acid etch, AB primer and AB adhesive, and (5) microetch, 37.5% phosphoric acid etch, AB primer and AB adhesive. Amalgam was condensed onto the treated RMGI surface. Samples were stored in water at 37 degrees C and tested at 24 hours for shear bond strength. The data was analyzed statistically by ANOVA followed by Scheffé post hoc tests for significance. Glass-ionomer discs were also treated as described in each group, sputter-coated and examined using a scanning electron microscope. RESULTS: No significant improvement in bond strengths to amalgam was observed with any of the treatments of the RMGI surface. Amalgambond significantly increased the bond strength of the amalgam to the RMGI.

Compomers↗
PubMedDate not supplied

Effect of accelerated aging on the color stability of cemented laminate veneers.

PURPOSE: The effect of the aging process on color stability of light-cure, dual-cure, and self-cure resin cements used for luting laminate veneers was investigated in this study. MATERIALS AND METHODS: Dyract Cem (self cure), Twinlook (dual cure), and En Force (light cure) cements, 0.30 mm thick, were polymerized on laminate veneers that were 13 mm in diameter and 0.50 mm thick in an A2 shade. Five specimens were made for each material. The specimens were subjected to an accelerated aging process in a Weather-Ometer for 900 hours. Spectrophotometric analyses were made after 300, 600, and 900 hours of accelerated aging time. Overall color difference (delta E*ab) was determined using the CIE-LAB system for measuring small color differences. Chroma changes (delta C*ab) and hue differences (delta H*ab) were also determined. delta E*ab, delta C*ab, and delta H*ab were analyzed by one-way analysis of variance, t test for dependent samples, and Tukey honestly significant difference (HSD) tests. RESULTS: delta E*ab values determined for the materials in this study varied in the acceptable range of 1.9 to 2.7. Different aging times caused no significant differences in delta E*ab, delta C*ab, or delta H*ab values for any of the materials. There were no significant differences in the amount of overall color change among the 3 resin cements at the same aging period. Twinlook material showed the greatest chroma change at each aging time. The greatest hue change was determined for Dyract Cem material. CONCLUSION: The light-cure resin cement tested can be proposed as a suitable material for luting laminate veneers, but long-term clinical studies are necessary to verify these experimental findings.

Algorithms↗
PubMedDate not supplied

Two-year clinical performance of a polyacid-modified resin composite and a resin-modified glass-ionomer restorative material.

This study compared the clinical performance of a polyacid-modified resin composite and a resin-modified glass-ionomer restorative material over two years. Thirty-four pairs of restorations of Compoglass and Fuji II LC were placed in caries-free cervical erosion/abfraction lesions without tooth preparation. Restorations were clinically evaluated at baseline, 6, 12, 18 and 24 months using modified Ryge/USPHS criteria. A significantly higher incidence of failed restorations was found with the polyacid-modified resin composite (p < 0.05).

Adult↗
PubMedDate not supplied

Marginal adaption of Class V restorations with and without "softstart-polymerization".

Polymerization shrinkage causing marginal gap formation is still a major problem in light curing restorations. The aim of the present study was to test the influence of "softstart polymerization" (prepolymerization at a low light intensity followed by a final cure at a high light intensity) on the marginal integrity of polyacid-modified resin and composite resin restorations in Class V cavities using a commercially available curing unit with two defined curing intensities. Sixty standardized Class V cavities were prepared. Twenty cavities at a time were filled either with a composite resin [Spectrum + Prime & Bond 2.1 (SP)], or with polyacid-modified resins [Dyract + Prime & Bond 2.1 (DY); Hytac + OSB Primer (HY)]. Ten fillings of each group were either conventionally cured (40 seconds, 800 mW/cm2), or they were cured with a lower starting intensity (10 seconds, 150 mW/cm2) and then with the full intensity (30 seconds, 800 mW/cm2). Margins were evaluated before and after thermomechanical loading (TCML) by quantitative margin analysis. Microleakage was assessed by dye penetration. The softstart polymerization showed no significant influence on gap formation for each material and interface before and after TCML. Quantitative margin analysis after TCML showed significantly fewer marginal gaps at the enamel/restoration interface for SP (0%) compared to DY (15.5%) and HY (44.5%) using softstart polymerization. At the dentin/restoration interface the corresponding results for gap formation were 29.6% for SP, 8.5% for DY, and 21.0% for HY. These results were not significantly different from each other. Dye penetration was significantly higher for SP at the dentin/restoration interface. SP showed significantly more marginal swelling at the dentin/restoration interface compared to DY. In conclusion, softstart polymerization using a very low starting intensity did not improve the marginal adaptation of polyacid-modified resins or composite resins in Class V cavity preparations. The best marginal adaptation in Class V cavities at the enamel/restoration interface was achieved with SP, using the acid-etch technique. In dentin, however, the polyacid-modified resins showed a superior marginal adaptation.

Compomers↗
PubMedDate not supplied

Polymerization shrinkage of visible-light-cured composites.

This study investigated the long-term dimensional changes of a conventional and a polyacid-modified composite resin and the effects of hydration on polymerization shrinkage. A strain-monitoring device was used to measure the linear polymerization shrinkage of the composites in the free state when stored in water at 37 degrees C or air at 26 degrees C over a one-month period. Results showed that the polymerization reaction of both conventional and polyacid-modified composite resins was accompanied by a dimensional shrinkage change. The rate of shrinkage for both composites was greatest during the polymerization reaction and continued after removal of the curing light. When stored in water, the greatest shrinkage was noted at one hour for both materials. This was followed by a slow uptake of water and expansion from one day to one month. The polyacid-modified composite had significantly less polymerization shrinkage than the conventional composite after one month of storage in water.

Air↗
PubMedDate not supplied

Three-year clinical evaluation of a polyacid-modified resin composite (Dyract).

The aim of this study was to clinically evaluate a polyacid-modified resin composite (Dyract; Dentsply deTrey). Forty-one Dyract restorations were placed (36 in noncarious cervical cavities and five in anterior approximal cavities), and assessed after three years. The retention rate was 97% for the cervical restorations; however, 16 restorations showed some degree of marginal discoloration, sometimes severe. Color match and surface integrity were highly satisfactory throughout the trial. Dyract has now been superseded by Dyract AP, and the manufacturers should consider recommending mandatory enamel etching.

Acid Etching, Dental↗
PubMedDate not supplied

Effect of food-simulating liquids on surface characteristics of composite and polyacid-modified composite restoratives.

The chemical environment is one aspect of the oral environment that could have an appreciable influence on the in vivo degradation of composite resins. The effects of food-simulating liquids on the surface roughness and hardness of composite (Silux Plus, Z100, Spectrum TPH, and P50) and polyacid-modified composite resins (F2000 and Dyract AP) were thus investigated and compared. Sixty disks of each material were made. Half were used for microhardness testing and the remaining half for studying surface roughness using profilometry. Each group of 30 disks was subdivided into six groups of five and conditioned for one week as follows--Group 1 (control): air at 37 degrees C; Group 2: distilled water at 37 degrees C; Group 3: 0.02 N citric acid at 37 degrees C; Group 4: 0.02 N lactic acid at 37 degrees C Group 5: heptane at 37 degrees C; Group 6: 50% ethanol-water solution at 37 degrees C. Data were analyzed using one-way ANOVA and Scheffé's test at a significance level of 0.05. Results showed that the surface roughness of all restoratives evaluated was not significantly affected by food-simulating liquids. No significant change in surface hardness was noted with conditioning of Spectrum TPH, Dyract AP, and F2000 in the various food-simulating liquids. The BIS-GMA-based composites Silux Plus, Z100, and P50 appeared to be more susceptible to the softening effects of some food-simulating liquids.

Air↗
PubMedDate not supplied

Effect of food-simulating liquids on the flexural strength of composite and polyacid-modified composite restoratives.

This study investigates the effects of food-simulating liquids on composite and polyacid-modified composite restoratives. Three composite (Z100, Spectrum TPH, and Tetric Ceram) and three polyacid-modified composite (F2000, Dyract AP, and Compoglass) restoratives from the same manufacturers were selected for the study. Flexural strength specimens (25 x 2 x 2 mm) based on ISO 4049 specifications were fabricated according to the manufacturers recommendations. After light polymerization, the specimens were removed from their molds and conditioned for one week at 37 degrees C in the following mediums: (1) deionized water, (2) 0.02 M citric acid, (3) heptane, and (4) 50% ethanol-water solution. Specimens stored in air were used as controls. The sample size was five for each material-medium combination. After conditioning, the specimens were blotted dry, measured, and subjected to flexural strength testing using an Instron Universal Testing Machine with a crosshead speed of 0.05 mm/minute. With the exception of Compoglass, flexural strength of all restoratives after conditioning in heptane was significantly greater than that after conditioning in all other mediums and the control. Although no significant difference in flexural strength values was observed between the different restoratives when the materials were conditioned in heptane or air (control), significant differences were observed between the different restoratives after conditioning in aqueous solutions (water, citric acid, and ethanol-water solution). The flexural strengths of the composites were generally significantly higher than their polyacid-modified counterparts after conditioning in the various aqueous solutions. The detrimental effects of aqueous solutions on flexural strength appeared to be greater with polyacid-modified composite resins than with composite restoratives.

Air↗
PubMedDate not supplied

Class II restorations with a polyacid-modified composite resin in primary molars placed in a dental practice: results of a two-year clinical evaluation.

This study evaluated the two-year success rate of a hybrid composite material (TPH-Spectrum; Dentsply DeTrey, Konstanz, Germany) and a polyacid-modified composite resin (Compoglass, Vivadent, Schaan, Liechtenstein) in Class II restorations placed in primary molars in a dental practice. In each of 52 children, at least two primary molars were restored. Ninety-six primary molars were filled with TPH-Spectrum using the total-etching technique, and 94 with Compoglass without acid etching prior to application of the bonding adhesive. At baseline, one and two years, the restorations were assessed according to the Ryge criteria. Forty-seven children with a total of 132 fillings (68 TPH-Spectrum, 64 Compoglass) were evaluated after two years. The cumulative success rate after 24 months amounted to 89.2% for the Compoglass and 89.7% for the TPH-Spectrum restorations. No significant differences were observed between the two materials with respect to color matching, cavosurface discoloration, anatomic form, margin integrity and caries assessment. This investigation suggests that for a period of two years, the hybrid composite TPH-Spectrum and the polyacid-modified composite resin Compoglass, are suitable materials for restoration of primary molars.

Acid Etching, Dental↗
PubMedDate not supplied

Influence of dentin conditioning and contamination on the marginal integrity of sandwich Class II restorations.

This study investigated the influence of dentin conditioning and contamination on the marginal adaptation of Class II sandwich restorations. Large butt-joint MOD cavities with cervical margins located 1 mm below the CEJ were cut into 72 extracted human molars. Nine groups were filled using a total-bond technique with Z100 or a sandwich technique with either Vitremer or F2000 in combination with Z100. For all three material combinations three different pretreatments were compared: total etch, selective etch and dentin contamination with saliva and blood prior to primer/adhesive application. After water storage for 21 days and thermocycling (2000x, 5-55 degrees C) replicas were produced for quantitative marginal analysis in the SEM. Teeth were immersed in 0.5% basic fuchsin for 24 hours and dried. Percent dye penetration over the total marginal length was analyzed in three layers using a sequential grinding technique. Statistical analysis was performed using a two-way ANOVA. Post-hoc analyses were carried out with univariate Mann-Whitney-U-tests adjusting for multiple comparisons by a sequentially rejective test procedure (Bonferroni-Holm) at p < 0.05. Both F2000 and Vitremer sandwich restorations showed better marginal adaptation than Z100 total-bond restorations with all pretreatments. Acid etching of the dentin significantly influenced the marginal adaptation of Z100 total-bond restorations and Vitremer sandwich restorations. All types of restorations showed considerable microleakage. On contaminated dentin, sandwich restorations showed better marginal integrity than total-bond restorations. Marginal adaptation did not correspond with microleakage in all groups. In conclusion, F2000/Z100 and Vitremer/Z100 sandwich restorations show better marginal adaptation than Z100 total-bond restorations in large Class II cavities with cervical margins in dentin. Microleakage cannot predictably be prevented with the sandwich technique. Sandwich restorations seem to be less sensitive to contamination with saliva and blood.

Acid Etching, Dental↗
PubMedDate not supplied

Brushing abrasion of luting cements under neutral and acidic conditions.

Four resin based materials (Compolute Aplicap, ESPE; Variolink Ultra, Vivadent; C&B Metabond, Parkell and Panavia 21, Kuraray), two carboxylate cements (Poly-F Plus, Dentsply DeTrey and Durelon Maxicap, ESPE), two glass-ionomer cements (Fuji I, GC and Ketac-Cem Aplicap, ESPE), one resin-modified glass ionomer cement (Vitremer, 3M) one polyacid-modified resin composite (Dyract Cem, Dentsply DeTrey) and one zinc phosphate cement (Harvard, Richter & Hoffmann) were investigated according to their brushing resistance after storage in neutral and acidic buffer solutions. For this purpose 24 cylindrical acrylic molds were each filled with the materials. After hardening, the samples were stored for seven days in 100% relative humidity and at 37 degrees C. Subsequently, they were ground flat and polished. Then each specimen was covered with an adhesive tape leaving a 4 mm wide window on the cement surface. Twelve samples of each material were stored for 24 hours in a buffer solution with a pH of 6.8. The remaining 12 samples were placed in a buffer with a pH of 3.0. All specimens were then subjected to a three media brushing abrasion (2,000 strokes) in an automatic brushing machine. Storage and brushing were performed three times. After 6,000 brushing strokes per specimen, the tape was removed. Brushing abrasion was measured with a computerized laser profilometer and statistically analyzed with ANOVA and Tukey's Standardized Range Test (p < or = 0.05). The highest brushing abrasion was found for the two carboxylate cements. The lowest brushing abrasion was found for one resin based material, Compolute Aplicap. With the exception of three resin-based materials, a lower pH led to a higher brushing abrasion.

Analysis of Variance↗