Influence of increment thickness on radiant energy and microhardness of bulk-fill resin composites.

Determining the energy transferred at the bottom of eleven bulk-fill resin composites, comparing top and bottom microhardness's and evaluating the correlation between microhardness and radiant energy were aimed. Samples were placed over the bottom sensor of a visible light transmission spectrophotometer and polymerized for 20 s. The bottom and top Knoop microhardness were measured. Paired t-test and correlation analysis were used for statistics (p≤0.05). In all groups, the bottom radiant energy decreased significantly with increasing thickness. For groups of Aura 2 mm, X-tra Fil 2 and 4 mm, SDR 2 and 4 mm, X-tra Base 2 mm no significant difference was found between top and bottom microhardness. For the bottom levels of Aura, X-tra Fil, Filtek Bulk-Fill Posterior, SDR, X-tra Base groups no significant difference was found between the microhardness's of 2 and 4 mm thicknesses. For X-tra Fil, Tetric Evo Ceram Bulk-Fill, Filtek Bulk-Fill Flowable and Z100 groups radiant energy affected positively the microhardness.

Intrapulpal temperature changes during curing of different bulk-fill restorative materials.

The aim of this study was to evaluate the intrapulpal temperature changes during the curing of different bulk-fill restorative materials. Ten mandibular molar teeth were selected and occlusal surfaces were removed to obtain a standard 0.5 mm occlusal dentin thickness. Five bulk-fill restorative materials and a conventional resin composite (control) were applied. The intrapulpal temperature changes during the curing of these materials were determined by a device simulating pulpal blood microcirculation. The difference between the initial and maximum temperature values (Δt), was recorded. The data were statistically analyzed with one-way ANOVA and Tukey's HSD test (p<0.05). There were statistically significant differences between materials (p<0.001). The light-curing bulkfill restoratives exhibited the highest Δt values. Equia Forte showed the lowest Δt values among all the groups (p<0.05). Bulk-fill restorative materials causes significantly different temperature changes in the pulp chamber according to curing type. Therefore, clinicians should be considered when using these materials.

Can Reduced-Step Polishers Be as Effective as Multiple-Step Polishers in Enhancing Surface Smoothness?

OBJECTIVES: The aim of this study was to evaluate the effects of various finishing and polishing systems on the final surface roughness of a resin composite. Hypotheses tested were: (1) reduced-step polishing systems are as effective as multiple-step systems on reducing the surface roughness of a resin composite and (2) the number of application steps in an F/P system has no effect on reducing surface roughness. MATERIALS AND METHODS: Ninety discs of a nano-hybrid resin composite were fabricated and divided into nine groups (n = 10). Except the control, all of the specimens were roughened prior to be polished by: Enamel Plus Shiny, Venus Supra, One-gloss, Sof-Lex Wheels, Super-Snap, Enhance/PoGo, Clearfil Twist Dia, and rubber cups. The surface roughness was measured and the surfaces were examined under scanning electron microscope. Results were analyzed with analysis of variance and Holm-Sidak's multiple comparisons test (p < 0.05). RESULTS: Significant differences were found among the surface roughness of all groups (p < 0.05). The smoothest surfaces were obtained under Mylar strips and the results were not different than Super-Snap, Enhance/PoGo, and Sof-Lex Spiral Wheels. The group that showed the roughest surface was the rubber cup group and these results were similar to those of the One-gloss, Enamel Plus Shiny, and Venus Supra groups. CONCLUSIONS: (1) The number of application steps has no effect on the performance of F/P systems. (2) Reduced-step polishers used after a finisher can be preferable to multiple-step systems when used on nanohybrid resin composites. (3) The effect of F/P systems on surface roughness seems to be material-dependent rather than instrument- or system-dependent. CLINICAL SIGNIFICANCE: Reduced-step systems used after a prepolisher can be an acceptable alternative to multiple-step systems on enhancing the surface smoothness of a nanohybrid composite; however, their effectiveness depends on the materials' properties. (J Esthet Restor Dent 29:31-40, 2017).

In vitro abrasion of resin-coated highly viscous glass ionomer cements: a confocal laser scanning microscopy study.

OBJECTIVES: The aim of this study was to evaluate the effect of resin coating on the wear depth of highly viscous glass ionomer cements (HVGICs) after 40,000 cycles, corresponding to over 8 years of tooth brushing. MATERIALS AND METHODS: A resin composite (Gradia Direct Posterior), two HVGICs (EQUIA Fil and Riva Self Cure), a resin coating (EQUIA Coat) and a conventional varnish (Fuji Varnish) were used in the study. The control groups were the resin composite group and the non-coated HVGICs groups. Samples (n = 8) were produced in flat plastic moulds at 23 ± 1 °C and stored in artificial saliva sodium acetate-acetic acid-glycerine formalin (SAGF medium) for 7 days at 37 ± 1 °C. The abrasion test was carried out in a toothbrush simulator (Willytec) with a load of 1 N using abrasive toothpaste slurry. Vertical loss was measured at different cycles under confocal laser scanning microscopy (CLSM). Data were analysed using one-way ANOVA, Tukey's HSD test, repeated measures ANOVA and Bonferroni tests (p < 0.05). RESULTS: The resin composite group showed significantly lower vertical wear loss than the non-coated groups and the varnished groups of HVGICs (p < 0.05). HVGICs with resin coating had better wear resistance than the varnished and non-coated groups (p < 0.05). Furthermore, regarding the material-based wear, HVGICs with resin coatings abraded less than the resin composite group tested (Gradia Direct Posterior 5.06 ± 0.54 µm, EQUIA Fil 4.06 ± 1.68 µm, Riva Self Cure 4.73 ± 2.44 µm), but statistically, there were no significant differences between them after 40,000 cycles (p > 0.05). After 40,000 cycles, when the total wear loss of the materials including both coatings wear was compared, there were no differences between the non-coated and the resin-coated groups. CONCLUSIONS: The results of this study indicate that the resin coating protects the glass ionomer materials from excessive wear until 20,000 cycles making both HVGICs to abrade in a similar manner as the resin composite. If we include the wear of the coating to the general material wear loss at 40,000 cycles, the total wear loss is quite similar for all HVGICs, regardless of the protection with varnish or resin coating. CLINICAL RELEVANCE: Within the limitation of this study, we have foreseen that resin coating will protect and make the HVGIC materials as wear resistant as resin composites in clinical situations for a long time.

Color changes of dental resin composites before and after polymerization and storage in water.

UNLABELLED: The aims of this study were to: (1) evaluate the A2 shades of various types and brands of resin composites to determine if any color differences occurred before and after polymerization and after 1 month of storage in water and (2) examine the correlation among the color changes and changes in Commission internationale de l'éclairage L*, a*, and b* values after polymerization and after 1 month of storage in water. One submicron-hybrid (Spectrum TPH3, DENTSPLY DeTrey, Milford, DE, USA), one nano-filled (Filtek Supreme XT, 3 M ESPE, St. Paul, MN, USA), three micro-hybrid (Filtek Z250, 3 M ESPE; Esthet X, DENTSPLY DeTrey; and Gradia Direct, GC, Tokyo, Japan), and five nano-hybrid (Ceram X, DENTSPLY DeTrey; Clearfil Majesty Esthetics, Kuraray, Osaka, Japan; Premise, Kerr Corporation, Orange, CA, USA; Tetric Evo Ceram, Ivoclar Vivadent, Schaan, Liechtenstein and Tetric N Ceram, Ivoclar Vivadent) light-curing resin composites were tested. The specimens (N = 10 for each composite) were prepared as discs, 12 mm in diameter and 2 mm in thickness, using round molds. The measurements were performed "before polymerization,""after polymerization," and "after 1 month of storage in water" using a contact type dental spectrophotometer (Vita Easyshade, Vident, Brea, CA, USA). The range of ΔE* values after polymerization (ΔE*1) and storage in water (ΔE*2) were 4.59 to 14.13 and 1.26 to 6.29, respectively. Nested analysis of variance and post hoc tests revealed that the type of resin composites significantly affected Δa*1, Δa*2, Δb*1, Δb*2, ΔE*2-values, whereas the brand of resin composites affected the changes in all color parameters (p < 0.05). In spite of many improvements in chemical compositions and fillers of the contemporary composites, color changes after polymerization were perceptible in all resin composites. However, color changes after storage in water were in the acceptable ranges for all resin composites except Clearfil Majesty Esthetic and Gradia Direct. CLINICAL SIGNIFICANCE: In spite of many improvements in chemical compositions and fillers of the contemporary resin composites, the color changes after polymerization were still perceptible in all the resin composites tested in this study, regardless of their types and brands. Such changes may cause esthetic problems clinically, thus should be taken into account when the shade selections are performed. Alternatively, a piece of unpolymerized resin material can be placed on, or adjacent to the tooth to be restored and polymerized to confirm the selected shade of the esthetic material.

Tensile bond strength of an aged resin composite repaired with different protocols.

PURPOSE: To evaluate the effect of different surface treatments and bonding procedures on the tensile bond strength (TBS) of resin composites repaired 6 months after polymerization. MATERIALS AND METHODS: Resin composite sticks were aged in distilled water at 37°C for 6 months. They were divided into 12 groups (n = 10) according to the combination of surface treatment/bonding procedures [none, only bur treatment, XP Bond (XPB/Dentsply/DeTrey) with/without bur, AdheSE (A-SE/Ivoclar/Vivadent) with/without bur, Composite Primer (CP/GC) with/without bur, CP after bur and acid-etching, XPB after acid etching and CP with bur, A-SE after bur and CP]. The ultimate tensile bond strength (UTS) of the resin composites was tested in intact but aged specimens. Tensile bond strengths were tested with a universal testing machine (Shimadzu). Data were analyzed using one-way ANOVA and Duncan Multiple Comparisons tests (p < 0.05). RESULTS: All repaired groups showed significantly higher TBS than the group without any sureface treatment (p < 0.05). Four groups resulted in TBS similar to those of intact resin composite UTS: A-SE, A-SE with bur, A-SE after CP with bur, and XPB after acid etching+CP with bur. CONCLUSION: Bur treatment, silane primer or etch-and-rinse adhesive application alone were not successful in the repair process of aged resin composite, whereas self-etching adhesive alone showed similar performance to the intact specimens. Combined procedures generally showed better performance: A-SE with bur, A-SE after CP with bur, and XPB after acid etching +CP with bur showed TBS similar to those of the intact specimens. It was concluded that bur roughening of the surfaces and rebonding procedures were essential for repairing aged resin composites.

Comparative radiopacity of six flowable resin composites.

OBJECTIVE: This study investigated the radiopacity of six commercially available flowable composites by using a digital image analysis method to determine the mean gray values of the materials. METHODS: The flowable resin composites evaluated in this study were Clearfil Majesty Flow, Estelite Flow Q, Tetric N Flow, Esthet X Flow, Filtek Supreme XT Flow and Gradia Direct LoFlo. Ten sample discs (6 x 1 mm) for each group were prepared and 1-mm thick slices were obtained from freshly-extracted teeth for the control group. The mean gray values (MGVs) of each specimen and aluminum (Al) stepwedge were measured by using the histogram function of a computer graphics program. Analysis of variance (ANOVA) was used to investigate the significance of the differences among the groups. For pairwise comparisons, the Tukey test was applied (alpha=0.05). RESULTS: The radiopacity values of Gradia Direct LoFlo, dentin and Estelite Flow Q were close to that of 1 mm Al. Tetric N Flow and Cl Majesty Flow were more radiopaque than enamel, whereas Filtek Supreme XT Flow had a similar radiopacity to enamel. CONCLUSION: The radiopacity of flowable composites varies considerably, and care must be taken when selecting an appropriate material to enable secondary caries detection under posterior composite restorations.

Bond strength of different dentin bonding systems to fluorotic enamel.

PURPOSE: The effect of three different bonding strategies on the shear bond strength of a resin composite to fluorotic enamel surfaces was investigated. MATERIALS AND METHODS: Thirty-six noncarious extracted human molars with fluorosis and 36 without fluorosis were scraped clean from any remaining tissue, and then were divided into three subgroups according to the tested dentin bonding systems. The resin composite was bonded to the teeth using three different adhesive systems: Peak LC Bond with an etch-and-rinse technique (Ultradent Products), Peak LC Bond with a self-etching technique using Peak SE Primer (Ultradent Products), and Xeno V (Dentsply Caulk) using a one-bottle self-etching technique. Following the photopolymerization of the resin composites, thermocycling was performed 5000 times. Shear bond strengths were tested using the Shimadzu Universal Testing Machine until failure. The analysis of the fractured enamel surfaces was performed using an optical microscope (Nikon ECLIPSE ME 600) at 10X and 1000X magnification, and the images were analyzed with an image analyzer (LUCIA 4.21). The data obtained were analyzed with two-way ANOVA and the Bonferroni test at a significance level of p < 0.05. RESULTS: Mean shear bond strengths in MPa of the groups were: Peak LC Bond, self-etching, on fluorotic enamel 13.23 +/- 2.58 and on nonfluorotic enamel 17.81 +/- 2.90; Peak LC Bond, etch-and-rinse, on fluorotic enamel 16.77 +/- 2.32 and on nonfluorotic enamel 21.13 +/- 2.74; one-bottle self-etching Xeno V on fluorotic enamel 10.79 +/- 2.14 and on nonfluorotic enamel 14.58 +/- 2.99. CONCLUSION: Fluorosis adversely affected the bonding performance of all the bonding systems to enamel. The use of the etch-and-rinse dentin bonding technique produced higher bond strengths of the resin composite tested to fluorotic and nonfluorotic enamel compared to both self-etching techniques.

Noncarious class V lesions restored with a polyacid modified resin composite and a nanocomposite: a two-year clinical trial.

PURPOSE: The purpose of this study was to compare the clinical performance of a polyacid modified resin composite and a nanocomposite applied with an antibacterial adhesive system over a period of 2 years in noncarious Class V lesions. MATERIALS AND METHODS: Twenty-four patients with at least two noncarious cervical lesions were enrolled in the study. The teeth were restored with a polyacid modified resin composite (Dyract eXtra, Dentsply DeTrey) or a nanocomposite (Filtek Supreme, 3M/ESPE). Fifty restorations of each material were placed with no marginal bevels and no mechanical retentions using an antibacterial self-etching adhesive system (Clearfil Protect Bond, Kuraray). All lesions were evaluated at baseline, 6, 12, and 24 months periods using the USPHS criteria for color match, marginal discoloration, marginal adaptation, caries formation, anatomic form, postoperative sensitivity, surface roughness, and retention. The changes across the four time points were assessed using Friedman and Wilcoxon Signed Ranks tests. The two restorative materials were compared in the same recall period for each of the criteria using chi-square test (p = 0.05). RESULTS: Dyract eXtra restorations exhibited a significantly better color match than Filtek Supreme restorations; however, all restorations in both groups were clinically acceptable. Filtek Supreme's retention rate (100%) was found to be significantly better than that of Dyract eXtra (96%). Two Dyract eXtra restorations were completely lost while one was partially fractured (p < or = 0.05). Significant differences were observed in marginal adaptation and color match of Filtek Supreme restorations and marginal discoloration of Dyract eXtra and Filtek Supreme restorations between the baseline and the 2-year scores (p < or = 0.05). CONCLUSION: Both restorative materials showed acceptable clinical performance in Class V noncarious lesions after 2 years of clinical service.

Effect of different laser devices on the composition and microhardness of dentin.

This study determined the compositional changes and microhardness of the cavity floor prepared by Er,Cr:YSGG and Er:YAG lasers and compared the results with the conventional method of bur preparation. Fifteen non-carious human molars were used in this study. On the buccal and lingual surfaces of each tooth, two cavities (mesio-distal 3 mm, inciso-gingival 3 mm, depth 2 mm) were prepared with two different laser devices (Er,Cr:YSGG laser; Waterlase MD and Er:YAG laser; KaVo Key Laser 3) and a high-speed turbine. The teeth were embedded into polyester resin and cross-sectioned. The microhardness measurements from the floor of each half cavity were recorded with the Vickers surface hardness tester. The remaining halves of the cavities were subjected to SEM-EDS atomic analysis. The results were statistically evaluated by one-way ANOVA and Kruskal Wallis tests (p = 0.05). No significant differences were observed among the microhardness values, quantities of Ca (Ca weight %), P (P weight %) and Ca/P ratio of the lased and conventionally prepared cavities (p > 0.05). The cavity preparation techniques and differences in laser devices did not significantly alter the composition and microhardness of dentin tissue. Both laser devices used in this study were observed to lead to minimal thermal damage in the dentin tissue and minimal thermally-induced changes in dentinal compositions.

Color stability of nanocomposites polished with one-step systems.

OBJECTIVE: This study compared the color changes of five novel resin composites polished with two one-step polishing systems when exposed to coffee solution. METHODS: The resin composites tested were Filtek Supreme XT, Grandio, CeramX, Premise and Tetric EvoCeram. A total of 150 discs (30/resin composites, 10 x 2 mm) were fabricated. Ten specimens/resin composites cured under Mylar strips served as the control. The other samples were polished with PoGo and OptraPol discs for 30 seconds using a slow speed handpiece and immersed in coffee (Nescafé) for seven days. Color measurements were made with Vita Easyshade at baseline and after one and seven days. Repeated Measures ANOVA and Bonferroni tests were used for statistical analyses (p< or =0.05). RESULTS: The differences between the mean DeltaE* values for the resin composites polished with two different one-step systems were statistically significant (p<0.05). After one week, all materials exhibited significant color changes compared to baseline. All Mylar finished specimens showed the most intense staining (p<0.05). There were no significant differences between the OptraPol and PoGo polished groups. Mylar-finished specimens of CeramX, Tetric EvoCeram, Premise and Filtek Supreme XT presented the greatest staining (p<0.05). For Grandio, there were no significant differences between the Mylar and PoGo groups, while the most stain resistant surfaces were attained with OptraPol. CONCLUSION: Removing the outermost resin layer by polishing procedures is essential to achieving a stain resistant, more esthetically stable surface. One-step polishing systems can be used successfully for polishing nanocomposites.

Long-term antibacterial effects and physical properties of a chlorhexidine-containing glass ionomer cement.

STATEMENT OF THE PROBLEM: Many regions in the world do not have electricity, water, or access to dental facilities that allows the treatment of caries with dental handpieces and rotary burs. For restorative techniques used in these regions, an antibacterial self-adherent glass ionomer material would contribute considerably. PURPOSE: This study aimed to test if chlorhexidine diacetate (Fluka BioChemika, Buchs, Switzerland)- or chlorhexidine digluconate (Sigma-Aldrich, Steinheim, Germany)-added ChemFil Superior glass ionomer cement (Dentsply DeTrey, Konstanz, Germany) had any long-term antibacterial effect against certain oral bacteria and to test the new formulation's physical properties. MATERIALS AND METHODS: ChemFil Superior was used as a control. Chlorhexidine diacetate (powder) was added to the powder and chlorhexidine digluconate (liquid) was mixed with the powder in order to obtain 0.5, 1.25, and 2.5% concentrations of the respective groups. Setting time, compressive strength, and acid erosion were tested according to ISO 9917-1. Working time, hardness, diametral tensile strength, and biaxial flexural strength were also determined. Long-term antimicrobial activity against S. mutans, L. acidophilus, and C. albicans were tested with the agar diffusion method. Analysis of variance (ANOVA) was used for comparison (p < 0.05). RESULTS: Regarding the immediate antibacterial effect for S. mutans, all the tested groups showed inhibitions of the strain compared with the control group (p < 0.05), with larger zones for the higher concentration groups and all the diacetates. For L. acidophilus, all the groups were effective compared with the control, but the greatest antibacterial effect was observed with the 2.5% diacetate group. The 2.5% group of chlorhexidine diacetate showed antibacterial activity up to 90 days against S. mutans and up to 60 days against L. acidophilus. The working and setting time, acid erosion test, diametral tensile strength, and biaxial flexural strength of the tested groups were not different from the control ChemFil group. However, the 1.25 and 2.5% groups of chlorhexidine diacetate had significantly lower compressive strengths than the control group. Lower hardness values were obtained with the 0.5 and 2.5% chlorhexidine digluconate groups in comparison with the control group. CLINICAL SIGNIFICANCE: The results of this in vitro investigation demonstrated that chlorhexidine diacetate or digluconate added to the ChemFil Superior glass ionomer material can exhibit long-term antibacterial effects against S. mutans and L. acidophilus without compromising the physical properties of the material.

Evaluation of the shear bond strength of 3 curing bracket bonding systems combined with an antibacterial adhesive.

INTRODUCTION: The purpose of this in-vitro study was to investigate the shear/peel bond strength of metal brackets bonded to human enamel with differently cured bonded systems combined with an antibacterial adhesive component. METHODS: One hundred twenty extracted molars were divided into 3 groups. Stainless steel brackets were bonded with 1 of 3 systems: group 1, no-mix bonding adhesive (Unite, 3M Unitek, Monrovia, Calif) (n = 40); group 2, 2-paste chemically cured bonding resin (Concise, 3M Unitek) (n = 40); and group 3, light-cured adhesive (Transbond XT, 3M Unitek) (n = 40). Each bonding group was separated into experimental (n = 20) and control groups (n = 20). In the 3 experimental groups, an antibacterial self-etch adhesive (Clearfil Protect Bond, Kurary, Osaka, Japan) was also applied to the enamel. Specimens in the control groups were bonded only with their relevant bonding systems according to the manufacturers' instructions. All specimens were stored in distilled water for 24 hours and thermocycled before testing. Debonded specimens were scored with the adhesive remnant index. RESULTS: The mean bond strengths (in megapascals) were 9.8 (control, 15.7) in group 1, 12.0 (control, 18.5) in group 2, and 11.6 (control, 12.4) in group 3. Statistical analysis with t tests showed no difference between group 3 and its control (P = .178), whereas groups 1 and 2 were statistically different from their controls (P = .000). CONCLUSIONS: The results indicated that the newly developed antibacterial self-etch adhesive can be combined with various bonding systems; achieved bond strengths were clinically more than satisfactory.

Clinical performance of novel resin composites in posterior teeth: 18-month results.

PURPOSE: The aim of this study was to evaluate the clinical success potential of two nanocomposites placed in posterior teeth using an antibacterial adhesive system over 18 months. METHODS: A total of 49 Class I and 47 Class II restorations were placed in the permanent teeth of thirty adult patients. The carious lesions were restored with Grandio (Voco) or Filtek Supreme (3M ESPE) using a two-step self-etching antibacterial adhesive system Clearfil Protect Bond (Kuraray). The restorations were finished with fine-grit diamond burs, Enhance polishing system, and Sof-Lex finishing brushes. The restorations were evaluated at baseline, 6, 12, and 18 months after placement using modified Ryge criteria for color stability, marginal discoloration, marginal adaptation, caries formation, anatomic form, postoperative sensitivity, surface roughness, and retention. RESULTS: The changes in the parameters were assessed using the Cochran Q test and the McNemar test at a significance level of p < 0.05. All restorations were classified as clinically satisfactory after 18 months. Statistical analysis demonstrated differences only in superficial roughness, with Grandio exhibiting more surface roughness than Filtek Supreme (p < 0.05). CONCLUSION: Posterior restorations built up with the novel nanocomposites using an antibacterial self-etching system showed satisfactory results at the 18-month recall appointment relative to all criteria except the surface texture in the case of Grandio. Further evaluations are necessary for a more in-depth analysis.

Shear bond strength of different adhesives to Er:YAG laser-prepared dentin.

PURPOSE: The aim of this study was to examine the influence of Er:YAG laser on the shear bond strength of three different adhesives to lased dentin. MATERIALS AND METHODS: Seventy specimens obtained from 35 extracted human molars were embedded in polyester resin and ground with silicon carbide papers. The samples were divided into seven groups. 1. Er:YAG laser (Key Laser 3, KaVo) + Clearfil Protect Bond (Kuraray); 2. Er:YAG laser + Clearfil tri-S Bond (Kuraray); 3. Er:YAG laser + 37% H3PO4 + Single Bond 2 (3M-ESPE); 4. Er:YAG laser + Single Bond 2; 5. conventional method + Clearfil Protect Bond; 6. conventional method + Clearfil tri-S Bond; 7. conventional method + 37% H3PO4 + Single Bond 2. The samples were subjected to shear bond testing 24 h after bonding. Statistical analyses were carried out by two-way ANOVA, t-test, one-way ANOVA, post-hoc Tukey's and Dunnett C test (p = 0.05). RESULTS: Only the Er:YAG laser + Clearfil tri-S Bond group demonstrated significantly higher bond strengths vs conventionally prepared specimens (p < 0.05). There were no significant differences between the shear bond strengths of Single Bond 2 adhesive applied to laser- vs bur-treated specimens (p > 0.05). In laser prepared samples, Clearfil Protect Bond showed the highest scores (p < 0.05), whereas in conventionally prepared groups, no statistical differences were observed between Clearfil Protect Bond and Clearfil tri-S Bond (p > 0.05). CONCLUSION: Er:YAG laser irradiation did not adversely affect the shear bond strength of Single Bond 2 and Clearfil Protect Bond to dentin, whereas it increased the shear bond strength values of Clearfil tri-S Bond.

Is an antibacterial adhesive system more effective than cavity disinfectants?

PURPOSE: To compare the antibacterial activity of an adhesive system containing an antibacterial monomer MDPB, Clearfil Protect Bond with three different cavity disinfectants, chlorhexidine gluconate-based Consepsis, benzalkonium chloride-based Tubulicid Red and 3% hydrogen peroxide. METHODS: Materials were tested using agar well technique and a tooth cavity model. The test materials were filled in the agar wells of plates inoculated with Streptococcus mutans. After 48 hours of incubation, the zones of inhibitions were measured in millimeters. For the tooth cavity model test, cylindrical cavities were prepared in the flat occlusal dentin of human extracted molars. The teeth were left in a broth culture of Streptococcus mutans at 37 degrees C for 72 hours allowing bacteria to invade. Teeth were then randomly assigned into five groups of five teeth (10 cavity preparations) each. In the first four groups test materials were applied into the cavities following the manufacturer's instructions and the cavities in the fifth group were left untreated for control. The teeth were kept in saline for 72 hours. Standard amounts of dentin chips were obtained from the cavity walls and the number of bacteria recovered was counted. RESULTS: The results were analyzed by ANOVA, Dunnett C and Bonferroni tests. For the agar well technique, Clearfil Protect Bond primer exhibited greater inhibition zones than all three cavity disinfectants (P< 0.05). When tested by the cavity method, the application of Clearfil Protect Bond system resulted in significantly less bacterial recovery than all disinfectants (P< 0.05). For both microbiological methods, there were no significant differences between the antibacterial activities of Consepsis and Tubulicid Red (P> 0.05). They were superior to hydrogen peroxide in the cavity test method (P< 0.05).

Bactericidal effect of Er,Cr:YSGG laser on Streptococcus mutans.

The aim of this study was to compare the antibacterial activities of Er,Cr:YSGG laser with two different power outputs against a chlorhexidine gluconate-based cavity disinfectant. A cavity tooth model test was used to determine the antibacterial activity. Four cylindrical cavities were prepared on the dentin surface of 10 bovine incisors and left in contact with Streptococcus mutans for 72 hours to allow bacterial invasion. Following which, Er,Cr:YSGG laser with 0.75 W and 1 W power outputs and a chlorhexidine gluconate-based cavity disinfectant were applied separately on one of the three infected cavities, whereas the fourth was left untreated for control. Standardized amounts of dentin chips were obtained from the cavity walls, and the number of bacteria recovered was counted. Statistical analysis was carried out using one-way ANOVA and Dunnett's C test (p=0.05). No significant differences were observed among the data obtained from the chlorhexidine gluconate-based cavity disinfectant and the two Er,Cr:YSGG laser groups (p>0.05). However, when compared to the control group, both Er,Cr:YSGG laser groups and the chlorhexidine gluconate-based cavity disinfectant resulted in significantly less bacterial recovery (p<0.05). In conclusion, the antibacterial activity on S. mutans demonstrated by Er,Cr:YSGG laser with both energy outputs was similar to that of the tested chlorhexidine gluconate-based cavity disinfectant.

Effect of an antibacterial adhesive on the bond strength of three different luting resin composites.

OBJECTIVES: Effect of a dentin adhesive system containing antibacterial monomer-MDPB (Clearfil Protect Bond) on the shear bond strength of all-ceramic-IPS Empress 2 restorations luted with three different dual-polymerizing systems (Variolink 2, RelyX ARC and Panavia F 2.0) to dentin was investigated. METHODS: One hundred and eight all-ceramic discs (2 x 3mm; IPS Empress 2) were fabricated and ultrasonically cleaned. The buccal surfaces of 108 non-carious extracted human premolars were flattened to expose dentin and subsequently polished with 600-grit wet silicon carbide paper. Three dual-polymerizing luting systems had test groups and control groups consisting of 18 samples each. For the test groups Clearfil Protect Bond was applied to the exposed dentin surfaces. Control groups received the original bonding procedures of each adhesive system. After the all-ceramic samples were luted to the teeth, thermocycling was performed 5000 times. Shear bond strengths were tested using Shimadzu Universal Testing Machine until failure. Analysis of fractured dentin surfaces were performed using Optical Microscope at x10 and x1000 magnifications and the images were analyzed with Image Analyzer. Data was analyzed with one-way ANOVA and Bonferroni test at a significance level of p<0.05. RESULTS: Mean shear bond strength data of the groups in MPa were; Variolink: 20.45+/-4.75, Variolink+Clearfil Protect Bond:29.32+/-2.37, RelyX ARC:18.82+/-3.19, RelyX ARC+Clearfil Protect Bond:25.58+/-4.05, Panavia F 2.0:17.11+/-2.98, Panavia F 2.0+Clearfil Protect Bond:24.40+/-7.46. Application of the antibacterial adhesive increased the shear bond strengths of all three dual-polymerizing systems to dentin (p=0.00). The surface analysis showed that most of the specimens showed the adhesive failure mode between the dentin and the composite luting agent interface. CONCLUSION: The antibacterial adhesive system Clearfil Protect Bond can be safely used to prevent the potential risk of complications resulting from bacterial activity regardless of affecting the bond strength of IPS Empress 2 restorations luted with the dual-polimerizing systems used in this study.

Stain retention and surface characteristics of posterior composites polished by one-step systems.

PURPOSE: To compare susceptibility to stain of three posterior composite surfaces polished with two one-step polishing systems, to test the efficiency of the re-polishing to remove the stain formed and to analyze the polished surfaces by SEM. METHODS: The resin composites tested were Clearfil Photo Posterior, SureFil and Filtek P60. The polishing systems used were Sof-Lex Brush and PoGo. Twenty-two discs of each material were fabricated and divided into two treatment groups of 11. Out of the latter, six were used for SEM evaluation for surface morphology and five for stain retention testing. The discs were roughened with silicon paper and polished for 30 seconds with each system. Specimens were immersed in coffee and distilled water for 7 days. Color measurements were made at baseline and after 1, 3, 5, and 7 days with a spectrophotometer. The specimens were then re-polished with the same systems and their colors re-measured. All comparison of color change and re-polishing were subjected to repeated measures ANOVA with a Bonferroni post hoc test (P < or = 0.05). RESULTS: After 1 week, the coffee stained all the resin composites. Clearfil Photo Posterior was the least stained composite while Filtek P60 was the most. Regardless of the materials, PoGo polishing was less susceptible to staining (P < or = 0.05). The color change could be partially removed with re-polishing. The surfaces of Sof-Lex Brush polished samples, except the Clearfil group, were scratched and thus more susceptible to stain retention.

The clinical performance of one- and two-step self-etching adhesive systems at one year.

BACKGROUND: The author compared the clinical performance of a two-step self-etching adhesive system and a one-step self-etching adhesive system over one year. METHODS: Thirty-five patients with noncarious cervical lesions were enrolled in the study. The author restored 163 lesions using a two-step (Clearfil Protect Bond, Kuraray, Osaka, Japan) or a one-step (Xeno III, Dentsply/DeTrey, Konstanz, Germany) self-etching adhesive system. Enamel margins were not beveled, and no mechanical retentions were placed. The author evaluted the restorations at baseline and at three, six, nine and 12 months after placement using modified Ryge criteria for color-matching ability, marginal discoloration, marginal adaptation, initial caries formation, anatomical form, postoperative sensitivity and retention loss. RESULTS: The author assessed the changes in the parameters using the Cochran Q test and the McNemar test at a significance level of .05. At one year, the retention rates for the restorations in the two-step group were 100 percent; they were 96 percent for the restorations in the one-step group. Of the retained 75 restorations from the one-step group, two had marginal discoloration and slight anatomical form problems. In both groups, color-matching ability and postoperative sensitivity remained excellent. CONCLUSION: The performance of both self-etching adhesive systems was excellent during this one-year clinical trial. However, the two-step system exhibited slightly better retention than the one-step system. CLINICAL IMPLICATIONS: The one- and two-step self-etching adhesive systems evaluated in this study provided excellent clinical retention in noncarious lesions without mechanical retention.