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Color stability of resin cements after accelerated aging.

PURPOSE: To study the color stability of different resin cements after accelerated aging. METHODS: The color stability of a self-adhesive resin cement (Unicem), one resin-based composite cement (Variolink II), one compomer cement (Principle) and one hybrid ionomer cement (FujiCEM) was studied. Two curing modes of Unicem (self-cured and dual-cured) and Variolink II (light-cured and dual-cured) were also tested. Specimen disks (n = 5) were prepared with a polytetrafluoroethylene split mold and subjected to accelerated aging for 150, 300 and 450 kJ/m2. Color (CIELAB system) was measured before and after each of the three aging cycles on a reflection spectrophotometer. deltaE*, deltaL*, deltaC* and deltaH* were calculated and analyzed by ANOVA. RESULTS: The largest color change occurred during the first 150 kJ/m2 aging cycle, where deltaE* values ranged from 5.6 to 20.5 with Principle showing the least color change and FujiCEM the most. The color changes of all the tested materials were perceptible. The greatest changes were recorded for deltaL* and/or deltaC*. All specimens became significantly rougher and showed evidence of cracking and degradation after aging except Variolink II.

Analysis of Variance↗

Importance of water sorption and solubility studies for couple bonding agent--resin-based filling material.

This study investigated the water sorption and solubility of two light-cured resin composites (Filtek P60 and Solitaire 2), one compomer (Compoglass F), one ormocer (Admira) and the associated bonding agents (Scotchbond 1 [Scotchbond 1 = Scotchbond Single Bond in USA], Gluma One Bond, Excite and Admira Bond, respectively) and of a RMGIC (Fuji II LC). Five disks of each product type were subjected to water sorption and solubility tests based on ISO 4049 requirements. The data were subjected to Kruskal-Wallis and non-parametric multiple-comparison tests using ranked sums at 95% confidence interval. Fuji II LC showed the highest water sorption (167.5 microg/mm(-3)). Fuji II LC and Compoglass F had higher solubility values (8.3 and 10.0 microg/mm(-3), respectively) than the other materials. Bonding agents have very high water sorption and solubility values (between 77.4 and 355.4 microg/mm(-3) and between 75.9 and 144.9 microg/mm(-3), respectively) compared to the restorative materials. Gluma One Bond and Admira Bond showed lower sorption and solubility than Excite and Scotchbond 1.

Absorption↗

Materials used to restore class II lesions in primary molars: a survey of California pediatric dentists.

PURPOSE: The purpose of this study was to determine which materials were most commonly used by pediatric dentists in California to restore Class II lesions in the primary dentition. METHODS: A questionnaire consisting of 18 multiple-choice questions was mailed to all 440 active members of the California Society of Pediatric Dentistry (CSPD). The questions related to the practitioners' material of choice for restoring Class II lesions in primary molars. RESULTS: A 66% response rate was received. For 57% of the respondents, amalgam was the material of choice for restoration of Class II lesions in primary molars. Twenty-nine percent selected composite, 5% glass ionomer, 6% compomer, and 1% (1 practitioner) stainless steel crowns. Sixty-eight percent responded that amalgam has historically proven to be a safe, reliable, and affordable material. The main reasons cited for using composite resin were "patient preference" (86%) and "better esthetics" (78%). Most practitioners used either a single-step (fifth-generation) or 2-step (fourth-generation) bonding agent (53% and 35%, respectively). When using a nonamalgam restorative material, 49% of practitioners used a traditional Class II amalgam preparation. The role of dental literature in treatment decision-making was not significantly related to the restorative material used. CONCLUSIONS: While amalgam was the most common material used for Class II restorations, nonamalgam materials were significantly popular among California pediatric dentists.

Attitude of Health Personnel↗

Effect of flexural load cycling on microleakage of extended root caries restorations.

This study evaluated the microleakage of resin-modified glass ionomer, flowable compomer and flowable resin composite restorations on a Class V cavity of simulated advanced root caries under a flexural load cycling condition. Thirty-six non-carious human maxillary premolars were mounted in cylindrical acrylic resin molds. The cavities were prepared in the proximal root surface, from the middle of the buccal surface to the middle of the lingual surface, approximately 1 mm below the cemento-enamel junction, 2 mm axial width and 1.2 mm in depth. The teeth were randomly assigned to one of three groups with 12 teeth in each group: Group 1: Cavity conditioner and Fuji II LC (GC America), Group 2: Prime & Bond NT and Dyract Flow (Caulk-Dentsply), Group 3: Excite and Tetric flow (Ivoclar/Vivadent). Specimens were settled laterally on a fatigue-testing machine that was adjusted to deliver a force of 60N. The specimens were load cycled at 1 Hz for 5000 cycles, placed in a staining solution and sectioned to evaluate microleakage penetration. Results indicate that the coronal and gingival margins showed significant microleakage differences among the three restorations (p<0.05). At the coronal margin, there was no significant difference between Groups 2 and 3. At the gingival margin, there was no significant difference between Groups 1 and 2. It was concluded that the marginal sealing ability of a flowable resin composite under a flexural cycling load was better than in other selected materials and that flowable resin composite with dentin adhesive was a desirable alternative for root caries restorations extended to the proximal surface.

Acrylic Resins↗

Microleakage of restorative techniques for pulpotomized primary molars.

PURPOSE: This study's purpose was to assess in vitro microleakage of different restorative materials after pulpotomies in primary molars. METHODS: Proximo-occlusal cavity preparations were prepared in 60 extracted primary molars. The selected teeth had at least 3 sound walls and one half to two thirds of root length remaining. Carious tissue was removed, pulpotomy was performed, and IRM filled the pulp chamber. The teeth were then randomly divided equally into 5 groups and restored as follows: (1) group 1 with a compomer; (2) group 2 with a reinforced glass ionomer material; (3) group 3 with amalgam; (4) group 4 with a stainless steel crown (SSC); and (5) group 5 with IRM only (control). After thermocycling for 500 cycles, teeth were immersed in dye for 24 hours and progressively ground prior to microleakage evaluation. The worst result for each section was logged and results were statistically analyzed (Kruskal-Wallis and Mann-Whitney). RESULTS: Group 1 showed the highest percentage of no leakage of all groups. Leakage from occlusal and cervical margins was markedly shown for all specimens of groups 2, 3, and 5. CONCLUSIONS: (1) Bonding agents and resin based restorations were able to provide the best total margin protection. (2) SSCs cemented with glass ionomer cement were unable to hermetically seal teeth; and (3) Tytin, Ketac Molar, and IRM restorations did not appear to be leakage-resistant materials for pulpotomies of primary molars.

Compomers↗

The effect of bleaching agents on the surface hardness of tooth colored restorative materials.

AIM OF THE STUDY: The aim of this study was to evaluate the effect of at-home (Opalesence/Dr. kit 15%, Ultradent, Products, Inc. South Jordan, UT, USA) and in-office (Superoxol 35%, Sultan Chemists, Inc., Englewood, NJ, USA) bleaching on the surface hardness of the following tooth colored restorative materials: composite resin, Point-4 (P4), Kerr Corporation, Orange, CA, USA; ormocer, Admira (AD),VOCO, Germany; compomer Dyract AP (DY), Dentsply DeTrey GmbH, Germany; and resin modified glass ionomer cement, Fuji II LC (FL), GC Corporation, Japan. METHODOLOGY: Sixty specimens were prepared; 15 specimens of each material (each group n = 5, control after 15 days, at-home and in-office). All specimens were stored in distilled water at room temperature for 24 hrs before testing. A universal testing machine (Micromet 2100 series micro hardness testers) was used for testing Vicker's surface hardness for the three groups for every tested material. All results were statistically analyzed with one way analysis of variance (ANOVA), Post hoc Tukey HSD tests (P < 0.05), and percentage changes for Tukey. RESULTS: All the tested materials showed an increase in Vicker's surface hardness between base line (24 hrs) and the control group after 15 days storage in distilled water except DY which showed a decrease in surface hardness. All tested materials showed a decrease in surface hardness from control group after 15 days and both at-home and in-office bleaching agents except DY which showed increased values. SIGNIFICANCE: At-home as well as in-office bleaching agents have a softening effect on some tooth colored restorative material, and the patient must be aware before using them.

Analysis of Variance↗

Influence of different adhesive restorative materials on mutans streptococci colonization.

PURPOSE: To evaluate the effect of some restorative materials on mutans streptococci colonization. METHODS: Awild strain of mutans streptococci was isolated from human dental plaque and a monospecific biofilm adherent to the surfaces of 12 adhesive restorative materials (F2000, Dyract AP, Compoglass F, Z100 MP, Filtek Z250, Clearfil, Ketac-Bond, Ketac-Fil Plus, Ketac-Molar, Fuji Cap II, Fuji Bond LC and Fuji II LC) were tested. A colorimetric technique (MTT assay), based on the reduction of a yellow tetrazolium salt to a purple formazan, was used to evaluate the biomass adherent to the disk surfaces after a 24-hour growth. RESULTS: One-way ANOVA showed that glass-ionomer cements (Fuji Cap II, Ketac-Bond, Ketac-Fil and Ketac-Molar) had similar antibacterial effects on mutans streptococci and were significantly more effective (P < 0.001) than all other products tested in reducing the biofilm development on their surfaces. The compomers (Dyract, Compoglass F and F 2000) showed a significantly higher value of bacterial colonization than all the other materials (P < 0.001).

Adhesives↗

Influence of initial water content on the subsequent water sorption and solubility behavior in restorative polymers.

PURPOSE: To evaluate the water sorption characteristics and solubility behavior of two resin-based composites, an ormocer, a compomer and a resin-modified glass-ionomer, according to ISO 4049 specifications and also without the initial desiccation cycle. METHODS: After polymerization, five disks (15 x 1 mm) of each material [Filtek P60 (P60), Solitaire 2 (SOL2), Admira (ADM), Compoglass F (COF) and Fuji II LC (FLC)] were desiccated until a constant mass (ml) was obtained. They were immersed in distilled water for 7 days and immediately weighed after that period (mass m2). Then disks were again desiccated and weighed every day for 35 days (mass m3). Sorption and solubility values were deduced from these different measures. Without initial desiccation mass m1 was obtained just after polymerization. RESULTS: Without initial desiccation, all the materials absorbed less water and solubility was 1.5 to 8 times greater than in standard experiment. For the two protocols, water sorption and solubility were significantly greater in FLC, and ADM showed the least weight loss of all the materials tested.

Absorption↗

The clinical evaluation of a single-bottle adhesive system with three restorative materials in children: six-month results.

This study was designed to evaluate the clinical performance of a single-bottle adhesive system with three restorative materials placed in children using the total-etch technique. One hundred thirty restorations were placed on conservative preparations in 36 children using the incremental placement technique in a clinical environment. The restorations were evaluated within a week of placement (baseline) and again after six months. The criteria evaluated included retention, color match, marginal discoloration, marginal integrity, surface roughness, postoperative sensitivity, recurrent caries, and wear. Indirect evaluations of anatomical form, marginal adaptation, and wear also were conducted. Clinical evaluation demonstrated no significant differences between the three restorative materials. Five restorations had to be replaced: two compomer, two packable composite, and one amalgam. There was no clinically detectable wear in any of the restorations.

Acid Etching, Dental↗

Surface roughness of different dental materials before and after simulated toothbrushing in vitro.

This study measured the effect of toothbrushing with a slurry of toothpaste on different dental materials that have been optimally polished. Specimens (n=8) of 21 dental materials, 16 resin composites, 1 amalgam and 4 ceramic materials, were subjected to 36,000 cycles (approximately five hours) of circular toothbrushing with a force of 1.7 N and a slurry of toothpaste (RDA 75) in a device for simulated toothbrushing. The unpolished enamel and dentin of extracted anterior teeth were used as a control. The mean roughness (Ra) was measured with an optical sensor (FRT MicroProf) before and after toothbrushing. To compare the roughness of the different materials, ANOVA with a post hoc Tukey B test was applied (p<0.05). Among the resin composites, the hybrid composites showed the greatest increase in mean roughness, while the microfilled composites and the compomer Compoglass F demonstrated the lowest increase. No statistically significant difference in roughness was found before and after simulated toothbrushing for the Amalcap amalgam, Esthet-X resin composite, TPH Spectrum resin composite, d.SIGN ceramic and the experimental ceramic. The other ceramic materials and dentin and enamel specimens showed a statistically significant decrease in mean roughness after simulated toothbrushing. Glazed Empress demonstrated a statistically significant higher initial roughness than polished Empress. For resin composites, no correlation was found between the mean particle size and mean roughness after simulated toothbrushing.

Aluminum Silicates↗

Color difference of four esthetic restorative materials by the illuminant.

PURPOSE: To determine the difference in lightness, chroma, hue angle and color of four kinds of esthetic restorative materials of the same shade designation by the change of standard illuminants of D65 (daylight), A (incandescent lamp) and F2 (fluorescent lamp). METHODS: Spectral reflectance and color of four resin composites, a glass ionomer, a resin-modified glass ionomer and a compomer of shade A2 were measured according to the CIELAB color scale relative to the illuminants D65, A and F2. Spectral reflectance curves were compared, and changes in lightness (deltaL*), chroma (deltaC*ab), hue angle (deltah degrees) and color (deltaE*ab) by the changes of illuminants from D65 to A or F2 were compared as "value relative to the illuminant A or F2 - value relative to the illuminant D65". RESULTS: In curves of spectral reflectance, the curves were in the similar range of reflectance (%) except glass ionomer. Changes in lightness were low (0.42-1.27), and changes in chroma were 0.26-2.23 for both conditions. These values were different by the kind of materials. The magnitude of the changes in hue angle was the most prominent in both conditions and was significantly different by the illuminants of A and F2 (P< 0.05). The range of color difference was 1.13-3.02 in both conditions.

Acrylic Resins↗

Non carious cervical lesions. A review.

Non-carious cervical lesions (NCCL) are characterized by a loss of hard dental tissue near the cement-enamel-junction. Commonly, their shape is like a wedge with the apex pointing inwards. Other times, they appear as regular depressions, like a dome or a cup. Their main characteristic is the presence of hard-mineralized tissue. According to the literature, the prevalence of cervical lesions is 85%, while their incidence is about 18% among permanent teeth. NCCL are currently classified as erosion, abrasion, or abfraction. Their etiology seems to be related to different factors: hexogen and endogen acids, mechanical abrasive action, tooth flexion under axial and non-axial loads. Moreover, it seems that a fundamental role is ascribable to tooth bending phenomena due to the strength components parallel or oblique to the occlusal level, which occur during the normal function as well as during parafunctions. The frequent therapeutic failures are probably due to the same factors causing the onset of the original lesion. Several materials have been proposed to restore NCCL: amalgam (abandoned), glass-ionomer cements, compomers, and composite resins. Early failures of these restorations have often been reported in the literature, probably due to the same factors which originally caused the lesions. Further investigations are required to determine more reliable restorative therapies.

Compomers↗

Effect of humidity on the volumetric polymerization shrinkage of resin restorative materials.

This study measured the volumetric polymerization shrinkage of three resin restorative materials under ambient (that is, room) relative humidity conditions and compared it with shrinkage occurring under a higher humidity condition that simulated the oral cavity. Small, semi-spherical specimens of a compomer, microfill composite, and flowable microhybrid composite were formed and light-activated using a halogen photocuring unit. The volumetric polymerization shrinkage of 15 specimens of each product was measured using a drop shape analysis unit for the relative humidity level of the ambient room (58.6 +/- 5.9%) and a higher humidity level that simulated the oral cavity (98.0 +/- 2.9%). Mean volumetric shrinkage values were calculated for each resin composite and the data were analyzed using a two-way analysis of variance (alpha = 0.05) to determine if significant differences existed between the amount of volumetric polymerization shrinkage that occurred under ambient room humidity conditions and the amount that occurred under simulated intraoral humidity conditions. Statistical analysis indicated that there was no significant difference (p = 0.17).

Compomers↗

Optical properties of four esthetic restorative materials after accelerated aging.

PURPOSE: To determine the differences in CIE L*, a*, and b* values, translucency parameter (TP), opalescence parameter (deltaO*ab), and color difference caused by the fluorescence (deltaE*ab-FL) of resin composite, glass-ionomer, resin-modified glass-ionomer, and compomer of A2 shade before and after accelerated aging. METHODS: Color and spectral distribution of the materials were measured according to the CIELAB color scale relative to the standard illuminant D65 in the transmittance and reflectance modes. Aging was performed in an accelerated aging chamber with an energy exposure of 150 kJ/m2. The translucency parameter (TP) was calculated as the color difference (deltaE*ab) of the specimen over white and black backgrounds. Opalescence parameter (deltaO*ab) was calculated as the difference in blue-yellow coordinate (deltab*) and red-green coordinate (deltaa*) between the transmitted and reflected colors of a 1 mm-thick specimen. Color difference by the fluorescence (deltaE*ab-FL) in reflectance mode was calculated as an index of fluorescence. Differences and changes in optical properties were analyzed by the repeated-measures ANOVA. RESULTS: Type of material and the mode of measurement (transmittance and reflectance) influenced CIE L*, a* and b* values significantly (P< 0.05) before aging. Accelerated aging influenced CIE L*, a* and b* values. Aging and the type of material influenced TP, deltaO*ab and deltaE*ab-FL values significantly (P< 0.05).

Analysis of Variance↗

[Effect in vitro of environmental parameters on the release of fluoride ions from some materials used in dentistry].

The aim of this in vitro study was to evaluate the influence of calcium ions and pH on fluoride release from selected dental materials. The materials studied included a resin composite (Te-Econom), fissure sealant (Conseal F) and compomer (Freedom). Samples were placed for 7 days in artificial saliva with or without calcium ions and pH ranging from 4.5 to 7.5. Fluoride release from the studied materials was measured with an ion-selective electrode (Orion). The results demonstrate differing effects of calcium concentration and pH on fluoride release. The highest cumulative fluoride release was observed from Freedom and the lowest from Te-Econom. Addition of calcium ions to the medium reduced the release of fluoride.

Acrylic Resins↗

Effects of repeated fluoride varnish application on different restorative surfaces.

AIM: The aim of this study was to assess the effect of repeated (twice) applications of two fluoride varnishes (Duraflor and CavityShield) on the surface micromorphology of a high-viscosity glass ionomer (Fuji IX GP), a compomer (F2000), and a flowable composite (Filtek Flow) using a profilometer and scanning electron microscope (SEM). METHODS AND MATERIALS: Fifteen specimens were prepared from each material, surface roughness (Ra) was measured with a profilometer, and an impression was made for epoxy replicas. The fluoride varnishes were applied to the experimental specimens of each material at repeated intervals of 48 hours. For all specimens, Ra was measured and SEM replicas were examined. RESULTS: The final Ra of glass ionomer was 3.49 +/- 0.59 (mean +/- SD) for CavityShield, 4.69 +/- 1.33 for Duraflor, and 2.96 +/- 1.53 for the controls. The final Ra of flowable composite was 0.53 +/- 0.20 for CavityShield, 2.61 +/- 3.08 for Duraflor, and 0.15 +/- 0.09 for controls. For glass ionomer and flowable composite, Duraflor was associated with a significantly higher roughness at the final measurement compared to controls (P < 0.05). SEM micrographs showed differing surface topographies which in many specimens confirmed Ra analysis. CONCLUSION: Fuji IX GP and Filtek Flow showed significantly higher roughness after two applications of Duraflor compared to controls.

Analysis of Variance↗

In vitro wear evaluation of dental materials in primary teeth.

PURPOSE: To evaluate the effect of dental materials on primary enamel wear. METHODS: Four composites (Filtek Z250, Heliomolar, Point 4, SureFil), two compomers (Dyract AP, F2000) and a resin-modified glass-ionomer (Vitremer) were placed into box-shaped preparations in buccal surfaces of primary molars and stored for 24 hours in water at 37 degrees C. The specimens (n = 6) were subjected to abrasive three-body wear against a primary enamel cusp. Material wear, enamel wear (adjacent to the material), and wear on enamel cusps were estimated by profilometry and video-analysis software. Results were compared with ANOVA and Tukey's tests (P < 0.05). RESULTS: Vitremer showed the highest wear (P < 0.05), followed by Dyract AP and F2000, which were not statistically different (P > 0.05). There was no significant difference between Filtek Z250 and Dyract AP (P > 0.05). Filtek Z250, Heliomolar, Point 4 and SureFil, showed the lowest wear values and there was no difference among them (P > 0.05). The highest wear values on the enamel adjacent to the material were found with Dyract AP (P < 0.05) and the lowest next to Point 4 and SureFil (P < 0.05). There was no difference in the wear of the enamel next to Vitremer, F2000, Heliomolar and Filtek Z250 (P > 0.05). Vitremer and F2000 caused the highest wear on enamel cusps (P < 0.05), and there was no statistically significant difference (P > 0.05) between them; SureFil caused the lowest wear (P < 0.05) on the opposing enamel. There was a correlation (r = 0.85) between wear of materials and wear on the enamel cusps, but not (r = 0.53) for the wear on enamel besides the restoration and wear on enamel cusps. SEM micrographs showed different surface characteristics of the materials after the wear test.

Analysis of Variance↗

[Composite polymers--an amalgam substitute for deciduous tooth cavities?].

In this prospective clinical study, 29 class II restorations in deciduous teeth were placed in 17 patients using the recently developed compomer Dyract. The restorations were clinically and macrophotographically evaluated immediately after placement and after 6 months in situ. In addition, marginal adaptation and loss of substance were quantitated using replicas. Clinical and macrophotographical findings were excellent. Quantitative marginal analysis scored 92.5% "continuous margin" immediately after placement of the restorations and 95.4% after 6 months. Mean loss of substance at the margins of the restorations was 20.8 microns with a standard deviation of 64.6 microns. Providing that the positive results of this short term study are confirmed by long term data, Dyract may replace amalgam in deciduous teeth.

Child↗