Effect of 1.23 percent APF gel on fluoride-releasing restorative materials

This study evaluated the effect of a 1.23 percent APF gel on the surface morphological characteristics and surface roughness of one high-viscosity (Fuji IX GP), three polyacid-modified resin-based composites (Dyract AP, F2000 and Compoglass F) (PMRC), and two resin-modified glass-ionomer cements (Vitremer and Fuji II LC). A microfilled nonfluoridated resin-based composite (Silux Plus) was used as a control. All materials were handled according to the manufacturers' instructions. The fluoride gel used in the study was a 1.23 percent acidulated phosphate fluoride gel (APF) (Nupro APF). The specimens were repeatedly exposed to the APF gel with cotton applicators for a period that simulated the equivalent of 4 yrs (1 min/6 mo) under prophylactic fluoride treatment. Average surface roughness (Ra) of the control and treated specimens was measured. Three separate Ra measurements along the direction of rotation of the finishing and perpendicular to the finishing direction and edge of the mold were made for each specimen surface. In each group, specimens with Ra closest to the mean were removed from the molds, sputter-coated with gold and examined using a scanning electron microscope. The results showed that all tested materials, except Vitremer, displayed increased surface roughness values following APF treatment. However, this was not statistically significant for Compoglass F, Vitremer and Fuji II LC. Among PMRC materials, F2000 displayed the highest Ra average value, although the differences between F2000 and Dyract AP and of Compoglass F and Dyract AP was not statistically significant. Comparisons of the Ra values between Silux Plus and the other test materials revealed statistically significant differences except for Dyract AP and Compoglass F. No statistically significant difference was found between the Ra values of Vitremer and Fuji II LC following APF treatment. Among all groups, Fuji IX GP displayed the highest surface roughness.     

The effect of current bleaching agents on the color of light-polymerized composites in vitro

STATEMENT OF PROBLEM: Bleaching agents may affect the color of existing composite restorations. PURPOSE: The purpose of this study was to compare the effect of 10% carbamide peroxide and 10% hydrogen peroxide on the color of light-polymerized hybrid, macrofilled, and polyacid-modified composites. MATERIAL AND METHODS: Two light-polymerized hybrid composites (3M Valux and Spectrum TPH), 1 macrofilled condensable composite (Solitaire), and 2 polyacid-modified composites (Dyract AP and Compoglass) were used. The hybrid composites served as controls. The color of 8 specimens of each material was analyzed by use of a spectrophotometer before bleaching. The specimens were then divided randomly into 2 subgroups (n=4). One group was immersed in 10% carbamide peroxide solution and the other in 10% hydrogen peroxide, for 8 hours each for 14 consecutive days. After bleaching, color changes (Delta E) were determined for each material and compared by use of the Kruskal-Wallis test, followed by the Mann-Whitney U test (P<.05). RESULTS: After bleaching with carbamide peroxide, the color changes (Delta E) for Dyract AP (2.18; SD = 1.41), Compoglass (1.14; SD = 0.26) and Solitaire (1.56; SD = 0.89) were higher than the color changes recorded for 3M Valux (0.63; SD = 3.60), and Spectrum TPH (0.66; SD = 1.24). The differences between materials bleached with carbamide peroxide were not statistically significant. After bleaching with hydrogen peroxide, the color changes for Dyract AP (9.39; SD = 0.53) and Compoglass (5.15; SD = 0.52) were higher than the changes recorded for Spectrum TPH (4.53; SD = 1.53) and 3M Valux (3.41; SD = 4.40), whereas the color change of Solitaire (3.69; SD = 0.57) was significantly higher than that of 3M Valux (P=.01). The color changes for all restorative materials tested were clinically detectable after the application of 10% hydrogen peroxide. However, clinically noticeable discoloration was observed only for Dyract AP treated with 10% carbamide peroxide. CONCLUSION: In comparison to 10% carbamide peroxide, 10% hydrogen peroxide caused more color changes in the composites tested.     

Effect of resin-based material combination on the compressive and the flexural strength

The mechanical properties, elasticity and compressive strength, of restorative materials play a crucial role during mastication for clinical performance of materials in particular stress bearing areas at posterior regions. This in vitro study was objected to evaluate the changes in the compressive and flexural strength of tooth-coloured resin-based dental restorations placed on flowable composites. Specimens in the control group were produced in cylindrical form for testing compressive strength and in quadrangular prism form for flexural strength test. Tetric Ceram, Charisma, Surefil, Admira and two compomers; Dyract AP and Compoglass F in test group specimens were fabricated by placing the control materials on different flowables. The material combinations were as follows: Tetric Ceram/Tetric Flow Charisma/Flowline, Surefil/Dyract Flow, Admira/Admira Flow, Dyract AP/Dyract Flow, Compoglass F/Compoglass Flow. Compressive strength values were measured at the Instron Testing Machine with a cross-head speed of 10 mm min(-1) while flexural strength were determined in three-point bending with a cross-head speed of 1 mm min(-1). One-way anova and Tukey's multiple comparison tests were performed for the statistical analysis. The flexural strength values of Tetric Ceram/Tetric Flow (135.9 +/- 3.2), Charisma/Flowline (120.4 +/- 5.6) and Compoglass F/Compoglass Flow (108.2 +/- 5.2) combinations were statistically greater than Tetric Ceram (110.8 +/- 10.5), Charisma (95.3 +/- 5.3) and Compoglass F (86.9 +/- 4.9). The results of the present study support the idea that the placement of flowable composite as a liner under the resin-based composite restoratives increase the flexural strength.     

Amalgam substitutes: a critical analysis

PURPOSE: Quality standards for restorations recently have been defined in Switzerland. Amalgam substitutes must meet restoration Grade 2 requirements (i.e., pulp and dental hard substance must be preserved, and both form and function of the tooth have to be reconstituted). The pertinent operative technique has to be simple and amalgam-like. A minimum service life of 8 years is required. This in vitro study investigated the clinical potential of several amalgam substitutes, taking into account the operative requirements, the defined restorative guidelines, and the required service life. MATERIALS AND METHODS: Potential amalgam substitutes evaluated in this study included compomers (Compoglass, Dyract, Dyract AP, Elan, F 2000) and resin-based composites (Alert, Ariston, Definite, Nulite, Solitaire, Surefil). The composites Adaptic and Tetric Cream, using a simplified placement technique, were tested as negative and positive controls, respectively. Marginal adaptation and wear properties were measured in vitro in mixed Class II cavities. Relative radiopacity was measured in terms of millimeters of equivalent aluminum. RESULTS: All compomers showed a radiopacity of 2.5 mm or more aluminum. Only Dyract AP and Elan were more wear resistant than amalgam. After stressing, the percentage of continuous margin was at best 31% overall and 17% in dentin only. Among resin-based composites, the minimum requirements of radiopacity were fulfilled only by Alert, Surefil, and Tetric. Only Definite, Surefil, Solitaire, and Tetric exhibited wear resistance greater than amalgam. After stressing, the best marginal qualities were 41% continuous margin overall, and 8% in dentin only.     

Effects of APF gel on the physical structure of compomers and glass ionomer cements

This study assessed the effect of an acidulated phosphate fluoride (APF) gel on the surfaces of eight modern esthetic restorative materials. Five specimens each of three high powder: liquid ratio conventional glass ionomer cements (ChemFlex, Fuji IX GP, Ionofil Molar), four polyacid-modified resin composites (compomers) (Compoglass F, Dyract AP, Freedom, F2000) and an alkaline glass filled resin composite (Ariston pHc) were prepared and immersed at 37 degrees C in 2 mL of artificial saliva for six weeks. The aged specimens were then coated with 1.23% APF gel for four minutes, rinsed and again immersed in artificial saliva for another six weeks. The immersed, fresh specimens for each material were then examined with SEM and surface profilometry. After APF gel application, mean surface roughness (Ra) measurements and SEMs showed that roughness increased significantly, generally from the resin composite and compomers to the conventional glass ionomer cements (p < 0.05).     

Higher-concentration carbamide peroxide effects on surface roughness of composites

Background: Ten percent carbamide peroxide has been used extensively within the dental profession for the purpose of bleaching teeth. Although this method has been successful, the use of higher-concentration carbamide peroxides (20–35%) for home bleaching has increased substantially in the past few years. The purpose of this study was to evaluate changes in surface roughness of a hybrid and a microfilled composite after exposure to bleaching agents containing higher concentrations of carbamide peroxide.
Materials and Methods: Sixty-eight circular, resin-based composite specimens (8 mm ± 2 mm) were prepared against a Mylar surface. Half of the specimens were fabricated from a hybrid composite material and the other half with a microfilled composite. Specimens were polished with aluminum oxide finishing disks, divided into four groups, and then exposed either to 20% carbamide peroxide for 3 hours per day for 14 days or to 35% carbamide peroxide for 1 hour per day for 14 days. The mean surface roughness (Ra) was determined for each specimen before and after exposure to bleaching agents, using mechanical profilometry. Data were analyzed by two-way analysis of variance (ANOVA) for differences between composite type, carbamide peroxide concentrations, and interaction of the two factors with respect to average surface roughness. All data analysis was performed at α= 0.05.
Results: Mean change from baseline of surface roughness (R_a) of microfilled composite and 20% carbamide peroxide was −0.03 μm ± 0.10 um; microfilled composite and 35% carbamide peroxide: 0.01 pm ± 0.02 um; hybrid composite and 20% carbamide peroxide: −0.43 um ± 0.91 um; hybrid composite and 35% carbamide peroxide: −0.19 pm ± 0.43 pm. Surface roughness of hybrid or microfilled composite did not change significantly from baseline with either concentration of carbamide peroxide ( p = .300).     

The two-year clinical performance of esthetic restorative materials in noncarious cervical lesions

BACKGROUND: Materials used in restoration of cervical lesions include resin-modified glass ionomer cements, polyacid-modified resin-based composites and resin-based composites. In this study, the authors evaluated the clinical performance of these materials over a two-year period. METHODS: Thirty patients were enrolled in this study. The authors placed in these patients 130 restorations, 24 of which were Vitremer (3M Dental Products, St. Paul, Minn.), 38 were F2000 Compomer (3M Dental Products), 46 were Dyract AP (Dentsply DeTrey, Konstanz, Germany) and 22 were Valux Plus (3M Dental Products). Enamel margins were not beveled, and no mechanical retention was placed. Two independent, calibrated examiners evaluated the restorations baseline and at one and two years after placement using modified U.S. Public Health Service criteria. RESULTS: Retention rates at the end of two years were 100 percent for Vitremer, 67 percent for F2000 Compomer, 68 percent for Dyract AP and 70 percent for Valux Plus. The retention rate of Vitremer was significantly higher than that of the others (P < .05). In other categories, however, Valux Plus had the most favorable performance (P < .05). No secondary caries was detected around any restoration. CONCLUSION: Vitremer, with its high retention rate, seems to be the most appropriate material for restoration of noncarious cervical lesions, though it does not have the esthetic properties of resin-based composites. All materials used in this study were in need of improvements. CLINICAL IMPLICATIONS: Resin-modified glass ionomer cement, polyacid-modified resin-based composite and resin-based composite behaved differently in the restoration of noncarious cervical lesions. Therefore, clinicians should take factors such as esthetic needs and localization into account in selecting materials for such restorations.     

Mechanical properties of compomer restorative materials.

The purpose of this study was to measure the compressive strength, flexural strength, microhardness, and surface roughness of three compomers (Compoglass, Dyract, and Hytac) and compare the values to the ones obtained for a resin-modified glass-ionomer cement (Vitremer) and a resin composite (Z100). All materials were handled according to the manufacturers' instructions. There was a significant difference (P < 0.01) among Vitremer, Hytac and Z100 composite with regard to yield strength. Vitremer values were lower than for Hytac, which were lower than for Z100. The yield strength values for Compoglass and Dyract were significantly lower than for Hytac and Z100 composite and significantly higher than for Vitremer (P < 0.01). There was no significant difference in the strain at yield among Vitremer, Hytac, and Z100, but their values were significantly higher than for Compoglass and Dyract (P < 0.01). The flexural strength data displayed a significant difference between Vitremer and Hytac (P < 0.05). Z100 was significantly stronger than the other products tested. The values of strain at break for Vitremer, Hytac, and Z100 were significantly lower than for Compoglass and Dyract (P < 0.01). The compressive strength results showed significantly higher values for Dyract, Compoglass, and Hytac than for Vitremer (P < 0.01). Z100 displayed higher values than the other products tested (P < 0.01). Hytac strength was significantly higher than for Dyract (P < 0.01). The microhardness of Compoglass and Dyract was not significantly different (P < 0.05). Hytac displayed microhardness values higher than for Vitremer, Compoglass, and Dyract (P < 0.01). However, all products tested showed values significantly lower than for Z100 (P < 0.01). The surface roughness values for Compoglass, Dyract, Hytac, and Z100 were not significantly different. Vitremer displayed a significantly higher value than Dyract, Hytac, and Z100 (P < 0.05).     

Effects of dietary acids on surface microhardness of various tooth-colored restoratives

The aim of this in vitro study was to investigate if surface microhardness of Fuji IX GP, Vitremer, Dyract AP, and Prodigy is influenced by conditioning in aqueous solutions of lactic, orthophosphoric, citric, and acetic acids against bidistilled water (which was used as control). The pH values of acids used in this study were representative of dietary acids. All specimens were stored in bidistilled water for one week and then conditioned in the respective test solutions for another week. Citric (p<0.05) and acetic acids reduced, while lactic and orthophosphoric acids (p<0.05) increased the microhardness of both Fuji IX GP and Vitremer. On the other hand, microhardness of both Dyract AP and Prodigy was significantly reduced by all acidic media (p<0.05). The observed differences in the surface microhardness of various tooth-colored restorative materials conditioned in several media varied not only with the pH but also the nature of the acidic solution, and with the composition of the evaluated material.     

Two-year clinical evaluation of four polyacid-modified resin composites and a resin-modified glass-ionomer cement in Class V lesions.

OBJECTIVE: The aim of the study was to compare the clinical performances of four polyacid-modified resin composites (F2000, Dyract AP, Compoglass F, and Elan) and one resin-modified glass-ionomer cement (Vitremer) in Class V abrasion/erosion lesions. METHOD AND MATERIALS: Twenty restorations of each of the five restorative materials were placed in noncarious cervical abrasion/erosion lesions by one dentist. No cavity preparation was attempted. All teeth were isolated with cotton rolls and gingival retraction cord. The materials were manipulated according to the manufacturer's instructions and placed with the help of cervical matrixes. Restorations were finished and polished immediately after the placement. Evaluations were performed at baseline and 6 months, 1 year, and 2 years after placement for retention, color match, cavo-surface marginal discoloration, anatomic form, marginal adaptation, secondary caries, and postoperative sensitivity. RESULTS: Retention levels at 2 years were 90% for F2000, 90% for Dyract AP, 89% for Compoglass F, 84% for Elan, and 95% for the Vitremer restorations. No statistically significant differences were found among the materials after 2 years for any evaluation category. CONCLUSION: Polyacid-modified resin composite and resin-modified glass-ionomer cement restorations showed acceptable clinical performance after 2 years.     

In vitro inhibition of caries-like lesions with fluoride-releasing materials

The aim of this study was to compare the in vitro caries inhibition of various resin-based materials. Class V cavities were prepared in twenty-five freshly extracted human premolar teeth which were then restored with glass-ionomer cement (Chemfill II), compomer (Compoglass F, Dyract AP) and composite resin (Tetric Ceram and Z 100). The teeth were submerged in an acid gel for 6 weeks. Each specimen was sectioned. These sections were left in water for 24 hours, and then examined using polarized light microscopy. The lesion consisted of two parts, the outer surface lesion and the cavity wall lesion. There was no significant difference in the body depth of the outer lesion and in the depth of the wall lesion among teeth restored with Compoglass F, Dyract AP and Chemfill II (P > 0.05). There was a significant difference between those restored with Z 100 and Tetric Ceram (P < 0.05). The length of the wall lesion for the teeth restored with Chemfill II was significantly smaller than that in the remaining groups (P < 0.05). The length of the wall lesion for teeth restored with Tetric Ceram and Z 100 was significantly higher than in the remaining groups (P < 0.05). These results suggest that composite materials and compomer provide less caries inhibition than glass-ionomer cements.     

Effect of storage media upon the surface micromorphology of resin-based restorative materials

The aim of this study was to evaluate the effect of different storage media upon the surface micromorphology of resin-based restoratives. One resin-modified glass-ionomer (Fuji II LC Improved), one polyacid-modified composite resin (Dyract AP), one microfilled composite resin (Durafill VS), and one hybrid composite resin (Filtek Z250) were tested. For each material, 45 standardized cylindrical specimens were randomly made. After 24 h, samples were finished and polished, and their surface roughness measured to obtain Ra (micro m) baseline values (Bv). Fifteen specimens of each material were then stored at 37 +/- 1 degrees C, for 24 h, either in distilled deionized water or in artificial saliva, or else subjected to a pH-cycling regimen. At the end of 10 days of storage, final readings (Fv) of surface roughness were obtained. The Analysis of Covariance (alpha=0.05), considering the covariate Bv showed a significant interaction between restorative materials and storage media (P value=0.0000). Multiple comparison Tukey's test revealed that the surface roughness of resin-based restoratives subjected to a pH-cycling model was significantly higher compared with both distilled deionized water and artificial saliva. Micromorphological changes were noticed in a situation of acid challenge.     

Cytotoxicity of resin-based restorative materials on human pulp cell cultures

OBJECTIVE: The objective of this study was to determine the cytocompatibility of 5 different extracts of resin-based restorative materials (2 resin-modified glass ionomer cements, 1 compomer, and 2 composite resins) on human pulp cells. STUDY DESIGN: Set specimens from 2 resin-modified glass-ionomer cements (Fuji II LC and Fuji IX), 1 compomer (Dyract), and 2 composite resins (Tetric and Superfil) were eluted with culture medium for 2 and 5 days. The effects of resin-based restorative materials on human pulp cells were evaluated with cytotoxicity and mitochondrial activity assays. RESULTS: The results showed that the eluates from resin-modified glass-ionomer, compomer, and composite resins were cytotoxic to primary human pulp cells. In addition, Superfil, Fuji IX, and Tetric demonstrated an inhibitory effect on mitochondrial activity of human pulp cells. It was found that composite resin Superfil was the most toxic restorative material among the chemicals tested. CONCLUSION: The influence of the cytotoxicity depended on the materials tested. Compomer or light-curing resin-modified glass ionomer may initially react more favorably to pulp cells.     

Surface roughness assessment of resin-based materials during brushing preceded by pH-cycling simulations.

This study evaluated the surface roughness pattern of resin-based restorative materials during brushing preceded by a regimen that simulated a dynamic pH-cycling. Restoratives included two resin composites (Renamel Microfill and Charisma), two polyacid-modified composite resins (Compoglass-F and Dyract AP) and one resin-modified glass ionomer cement (Fuji II LC Improved). Twenty standardized cylindrical specimens of each material were prepared according to a randomized complete block design. After finishing and polishing, the average surface roughness (Ra) and profile-length ratio (LR) of the specimens were determined. The experimental units were subjected to a pH-cycling regimen, and then to 10,000 brushing strokes. New readings of both the Ra and LR parameters were obtained. The same protocol of pH-cycling, brushing simulation and surface roughness measurements were repeated 10 times. Data was analyzed using ANOVA according to split-plot design and Tukey's test. Results showed the pH-cycling followed by 10,000 brushing strokes provided a remarkable increase in Ra for all restorative materials except for Renamel. Throughout the brushing simulation, Renamel, Charisma, Compoglass-F and Dyract AP showed steady textures, whereas Fuji II LC Improved exhibited a progressive increase in surface roughness. Among the materials tested, Renamel presented the smoothest surface, followed by Charisma and Compoglass-F, which did not differ from each other except at the baseline. Dyract AP was different from both these materials except at the baseline. Fuji II LC Improved had the roughest surface texture.     

Influence of 30% hydrogen peroxide bleaching on compomers in their surface modifications and thermal expansion

The surface modifications and the coefficient of thermal expansion of compomers after treatment with a 30% hydrogen peroxide bleaching agent were investigated. Three compomers (Compoglass F, Elan and F2000) were nonbleached and bleached for 1 and 3 days. The surface modification and the coefficient of thermal expansion of each bleached compomer were evaluated using a scanning electron microscope and a thermomechanical analyzer, respectively. As a result, Compoglass F and Elan showed slight surface degradation, whereas F2000 showed many cracks on its surface and these cracks were not observed in Compoglass F and Elan. Bleached Elan and F2000 has changed to the extent where their the coefficient of thermal expansion increased compared with those of nonbleached specimens. In addition, bleached compomers showed a strong inverse correlation between the coefficient of thermal expansion and the volume percent of filler.     

Evaluation of weight loss and surface roughness of compomers after simulated toothbrushing abrasion test

This study aimed at analyzing the compomers wear by an "in vitro" toothbrushing abrasion test. The null hypotheses tested were that there would be no differences in weight loss and no significant changes in surface roughness of the compomers after this test. The utilized commercial brands were Dyract (Dentsply), Dyract AP (Dentsply), Compoglass F (Vivadent), Freedom (SDI), F2000 (3M ESPE), which were compared to the two resin composites Z100 (3M ESPE) and Silux Plus (3M ESPE). Ten cylindrical specimens for each commercial brand were prepared with 5mm diameter and 3mm thickness. An appropriate machine with soft bristle tips containing dentifrice solution and deionized water was used. A total of 100,000 brushing cycles were performed. The amount of weight loss was measured by the percentage alteration between the initial (before toothbrushing) and final weight (after toothbrushing), measured by a Sartorius analytical balance. The surface roughness change was determined by the percentage difference between initial and final means after 5 tracings by a T 1000 Hommel Tester roughness meter on the specimen's surfaces before and after toothbrushing abrasion test. The statistical analysis (Students paired t-test, ANOVA and Tukey, á=0.05) showed that all materials presented statistically significant weight loss and roughness increase after abrasion test. All compomers presented higher weight loss than resin composites. Freedom and Dyract AP presented the lowest weight loss among compomers. F2000 presented the worst abrasion resistance, without statistical differences with Dyract. For roughness changes, Dyract, Dyract AP, Z100, Compoglass F and Silux Plus showed the lowest surface roughness alteration, in increasing order, without statistical differences between them. Freedom was the statistically roughest material of the study.     

Effects of in-office bleaching products on surface finish of tooth-colored restorations

A number of "high power" in-office bleaching products have recently been re-introduced into the market. The use of such strong oxidizing agents has raised questions as to possible adverse effects on tooth structure and restorative materials. This study evaluated the effects of 35% carbamide peroxide (Opalescence Quick) and 35% hydrogen peroxide (Opalescence Xtra) on the surface finish of four tooth-colored restorative materials (Spectrum TPH, Dyract AP, Reactmer and Fuji II LC). Twenty-seven matrix-finished specimens of each material were fabricated, stored in distilled water at 37 degrees C for seven days and randomly divided into three groups. Specimens in Group 1 were stored in distilled water at 37 degrees C (control). Specimens in Groups 2 and 3 were treated with 35% carbamide peroxide and 35% hydrogen peroxide, respectively. A total of three 30-minute bleaching sessions were conducted at one-week intervals. Storage medium during the hiatus period was distilled water at 37 degrees C. Surface roughness measurements were carried out using profilometry after each bleaching session. Data was analyzed using ANOVA/Scheffe's test at a 0.05 significance level. No significant difference in surface roughness was observed between the bleached and the control groups for all materials. In-office bleaching products are not detrimental to the surface finish of composites, compomers, giomers and resin-modified glass ionomer cements.     

Color stability of fluoride-containing restorative materials

Six fluoride-releasing materials of shade A3 were tested: one glass ionomer (Fuji IX), one resin-modified glass ionomer (Photac-Fil), two compomers (F 2000 and Dyract AP) and two composites (Tetric Ceram and Solitaire). Disk-shaped specimens of each material were prepared according to manufacturer's instructions, polished and L*a*b* baseline measurements taken. Specimens were randomly divided into two groups and given four different treatments of UV light exposure and immersion in a staining solution. Chromo Meter color measurements were taken following each treatment. Two-way ANOVA and Duncan Multiple Range post-hoc tests were used to compare color changes as a function of the four treatment conditions and one-way ANOVA was used to compare materials for each treatment separately. The results showed significant difference in shade A3 between products. In general, the hydrophobic materials showed greater color stability and stain resistance than the hydrophilic materials. Tetric ceram had the best color stability and stain resistance, while Fuji IX had the least.     

Effects of sonic and ultrasonic scaling on the surface roughness of tooth-colored restorative materials for cervical lesions

This study investigated the effects of sonic and ultrasonic scaling on the surface roughness of five commonly used tooth-colored restorative materials for Class V cavities, including a flowable resin composite (Tetric Flow), a compomer (Compoglass F), a glass ionomer (Fuji II), a resin-modified glass ionomer (Fuji II LC Imp) and a resin composite (Z100). Twenty rectangular block specimens (16 x 6 x 1.5 mm) of each material were cured against matrix strips, then stored in artificial saliva for two months before performing the periodontal instrumentation. Each specimen was divided into two experimental zones, and both scaling treatments were performed on each sample. The surface roughness (Ra) of these materials was determined before and after the different instrumentations, and differences were evaluated with the use of a profilometer. Data were statistically analyzed using repeated measures of ANOVA with Tukey's multiple comparisons and paired t-tests at a significance level of 0.05. Significant increases in surface roughness of all test materials were recorded from both scaling treatments. With the exception of Tetric Flow, ultrasonic scaling had more adverse effects on the surface roughness of all test materials compared to sonic scaling. For the test materials Z100 and Tetric Flow, resin composites showed the least surface changes in both scaling treatments, while Fuji II glass ionomer demonstrated the greatest roughness after instrumentation. More importantly, the mean surface roughness values of several materials after instrumentation were above the critical threshold roughness of 0.2 microm.     

In vitro fluoride release from aesthetic restorative materials following recharging with APF gel

In this in vitro study, the fluoride ion release from three more-viscous conventional glass ionomer cements (GICs)--ChemFlex, Fuji IX GP, Ionofil Molar--four polyacid-modified resin composites (compomers)--Dyract AP, Compoglass F, Freedom, F2000--and a hybrid resin composite--Ariston pHc--were compared. The amounts of fluoride release from 3 x 2.7 mm specimens were measured over six weeks using a fluoride ion-selective electrode. After six weeks, the specimens were recharged with 2 ml of 1.23 per cent acidulated phosphate fluoride (APF) gel for four minutes. The recharged specimens were then assessed for the amounts of fluoride release over another six weeks. Statistical analyses were performed using one-way and repeated measures ANOVA. The GICs and Compoglass F showed significantly higher initial fluoride release rates during the first two days (p < 0.05). After the first two days, fluoride release rates from all materials dropped quickly and became essentially stabilized within three-five weeks, in an exponential mode. The recharging of the specimens with APF gel caused a brief, but significant, increase in fluoride release for all materials (p < 0.05), before decreasing to previous comparable rates. Compoglass F released relatively more fluoride, and Ariston pHc relatively less, after APF gel application than before. The lowest total amounts over the study were released by Dyract AP and Freedom. The newer compomers, as well as the newer more-viscous GICs, appear to act as fluoride reservoirs to varying extents.