Comparison of remineralization ability of tricalcium silicate and of glass ionomer cement on residual dentin: an in vitro study.

OBJECTIVE: This study aimed to compare the remineralization effects of a calcium silicate-based cement (Biodentine) and of a glass ionomer cement (GIC: Fuji IX) on artificially demineralized dentin. METHODS: Four standard cavities were prepared in dentin discs prepared from 34 extracted sound human third molars. In each disc, one cavity was covered with an acid-resistant varnish before demineralization (Group 1). The specimens were soaked in a chemical demineralization solution for 96 h to induce artificial carious lesions. Thereafter, one cavity each was filled with Biodentine (Group 2) and GIC (Group 3), respectively, and one carious lesion was left unrestored as a negative control (Group 4). Next, specimens were immersed in simulated body fluid (SBF) for 21 days. After cross-sectioning the specimens, the Ca/P ratio was calculated in each specimen by using scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX). Finally, data were analyzed using repeated-measures ANOVA with post-hoc Bonferroni correction. RESULTS: Both cement types induced dentin remineralization as compared to Group 4. The Ca/P ratio was significantly higher in Group 2 than in Group 3 (p < 0.05). CONCLUSION: The dentin lesion remineralization capability of Biodentine is higher than that of GIC, suggesting the usefulness of the former as a bioactive dentin replacement material. CLINICAL RELEVANCE: Biodentine has a higher remineralization ability than that of GIC for carious dentin, and its interfacial properties make it a promising bioactive dentin restorative material.

Comparison of Different Restoration Techniques for Endodontically Treated Teeth.

The aim of the present study is to evaluate the physical properties of endodontically treated teeth restored with five different restorative techniques and materials. Hundred and forty extracted human molar teeth were used. In addition to five restoration groups, specimens with no restorations were used as the negative control, and intact molar teeth were used as the positive control. For flexural strength tests, material specimens were made from 5 different materials using a mould according to ISO 4049 standards. One-way ANOVA revealed that the fracture resistance was significantly affected by the restoration type. SFRC group showed the best fracture resistance values, while lowest values were seen in the GWF group. The test results of flexural strength showed values between 140 and 184 MPa and modulus of elasticity between 6.33 and 18.89 GPa (p < 0.05). Under the limits of this study, results showed that SFRC can be used to increase the fracture resistance of ETT.

Efficacy of different calcium silicate materials as pulp-capping agents: Randomized clinical trial.

BACKGROUND/PURPOSE: Calcium hydroxide-based materials were the gold standard in vital pulp therapies for decades' despite of several shortcomings. However, calcium silicates have been discussed as an alternative to overcome these drawbacks. It was aimed to investigate the in-vivo effectiveness of different calcium silicates based materials in pulp capping in this study. MATERIALS AND METHODS: A parallel-design, randomized controlled trial with 213 patients who has deep dentin caries, vital pulps and without spontaneous pain or history of swelling was designed. 525 M teeth were randomized, blinded and allocated to one of the five groups for pulp capping treatment (n = 105). All teeth were followed up clinically and radiographically (after 1st, 6th, 12th and 36th months) by blinded investigators. The clinical and radiographic success, and the effect of the pulp exposure to the success rate analyzed with Wald chi-square and Z tests. RESULTS: Clinical and radiographic success of MTA+ (86.3%, 85.4%) and Biodentine (79.4%, 80.1%) were found the highest. Although results of Theracal LC group (72.1%, 73.6%) were better than Dycal group (69.4%, 70.2%), the difference was nonsignificant (p > 0.05). Only in light-cured groups, (TheraCal LC & LC Calcihyd) pulpal exposure size effected the success of the materials (p < 0.05). MTA+ and Biodentine resulted better scores, when compared with TheraCal LC in large pulpal exposures (p < 0.05). CONCLUSION: After 36-month follow-up, both MTA+ and Biodentine were found to be the appropriate material for direct pulp capping in permanent teeth. The filler ingredient of the Theracal-LC eases the usage of calcium silicates but decreases the success rate.

Comparative clinical evaluation of the efficacy of a new method for caries diagnosis and excavation.

AIM: The purpose of this study is to compare the efficiency of fluorescence-aided caries excavation (FACE) to remove carious dentin primary teeth with that of conventional methods. METHODS AND MATERIALS: After caries excavation was carried out, dentin surfaces were conventionally inspected using visual tactile criteria and 415 cavities which were classified as caries-free, re-inspected with Face-Light and caries detector dye (CDD) methods. Orange-red fluorescing areas classified as carious dentin, as well as stained carious dentin. All the data were recorded according to localization of the caries and determination efficiency of the methods. X(2) test was used to compare the mean values of both Face-Light and dye applications, while Wilcoxon test performed to evaluate the effectiveness for each diagnostic method. RESULTS: A total of 273 patients with 415 Class II (OM/OD) cavities (1.65 ± 0.52 teeth per patient) with carious lesions in molar and premolar teeth, were examined. Out of 415 teeth, in 149 teeth (35.9%) no caries findings had been illustrated. While FACE detected remaining carious or partially removed areas in 237 teeth (57.2%), CDD stained only 29 teeth by itself (P < 0.05). CONCLUSION: In conclusion, FACE has a higher detectability compared to visual inspection and caries detector dye in diagnosis and removal of carious dentin.

Effect of novel restoration techniques on the fracture resistance of teeth treated endodontically: An in vitro study.

The aim was to evaluate the effects of fiber-reinforced composite restorations and a bulk-fill resin composite on the fracture strength of mandibular premolars treated endodontically. Standard mesio-occluso-distal (MOD) cavities were prepared in 48 mandibular premolars. Following root canal treatment, teeth were assigned to four groups: Group 1, nano-hybrid resin composite; Group 2, polyethylene woven fiber plus nano-hybrid resin composite; Group 3, short fiber-reinforced resin composite plus nano-hybrid resin composite; and Group 4, bulk-fill resin composite plus nano-hybrid resin composite. Then, the teeth were subjected to the fracture toughness test. The data were analyzed statistically using one-way ANOVA, followed by Tukey's post-hoc test. The fiber-reinforced groups had better results than the nano-hybrid and bulk-fill composites (p<0.05), while the bulk-fill and nano-hybrid composite restorations gave similar results (p>0.05). Fiber-reinforcement improved the fracture strength of teeth with large MOD cavities treated endodontically. Bulk-fill composites can be used reliably as well as nano-hybrid composites.

Microleakage of 4 post-luting cements evaluated by the computerized fluid filtration method.

PURPOSE: The aim of this study was to evaluate the microleakage of 4 fiber post-luting systems using the computerized fluid filtration method. METHODS: 60 extracted human mandibular permanent premolar teeth were used for the study. The teeth were instrumented with Hedstroem files up to size 60, post spaces were prepared and then Unicore fiber posts were cemented using 4 luting systems. Group1: Duolink, Group 2: Resinomer, Group 3: Fuji Plus, Group 4: Multilink Sprint, Group 5: Positive Control, and Group 6: Negative Control. The samples were stored in distilled water for 2 weeks and then microleakage was evaluated. Data were analyzed with 1 way-ANOVA and Dunett T3 tests (P<.05). Groups 2 and 3 significantly exhibited higher microleakage values than groups 1 and 4 (P<.05). RESULTS: Resin cements used with total etch-bonding systems demonstrated lower microleakage values than the other cements. CONCLUSIONS: Reduction of steps in dentin conditioning of resin luting cements may have a promoting effect on microleakage.

Evaluation of the apical adaptation performance of various root canal instruments.

OBJECTIVE: The aim of this study was to evaluate the apical root canal adaptation performance of various root canal instruments. MATERIALS AND METHODS: A total of 40 freshly extracted single-rooted mandibular incisors were used in this study. Coroner parts of all teeth were removed from cemento-enamel junction and root canal of each tooth was explored with a size 8 K-file until the tip of the file was just visible at the apex. Working lengths (WLs) were determined as 1 mm short of these measurements. ProTaper, K-file, profile and hedstroem files were inserted into the root canals of 10 teeth to the WL following the flaring of the coronal and middle thirds. Instruments were fixed in the root canals with acrylic resin. The apical 1 mm of each root tip was ground on wet sandpaper to expose the canal and the instrument at the WL and the apical region of each tooth was examined under stereomicroscope. The stereoscopic images of the teeth were digitized and analyzed with software in order to determine the differences between the areas of root canals and file tips. Result data were analyzed using the one-way analysis of variance test (P = 0.05). RESULTS: There were no significant differences between apical file/root canal areas of the evaluated instruments (P > 0.05). CONCLUSIONS: None of the evaluated instruments performed a perfect adaptation with the apical root canal surface at the WL in mandibular incisors. Therefore, total removal of the debris from the apical canal surface may not be achieved when these filing instruments are used.

Influence of two desensitizer agents on the microleakage of adhesively luted ceramic inlays.

OBJECTIVES: The purpose of this study was to evaluate the effects of two different desensitizers (Hemaseal & Cide and Aqua Prep F) on the microleakage of ceramic inlay restorations luted with adhesive resin cement. METHODS: Cylindrical Class V cavities were prepared on the buccal surfaces of thirty extracted human third molars. One of the desensitizers (either Hemaseal&Cide, Advantage Dental Products Inc. or Aqua-Prep F, Bisco) was applied to the cavities. Ten samples were used as controls. Ceramic inlays were fabricated using the heat-pressed glass ceramic technique (IPS Empress II). Inlay restorations were luted using adhesive cement (Variolink II, Ivoclar-Vivadent). The restorations were properly finished, stored in distilled water at 37°C for 24 h and subjected to 1000 thermal cycles. The microleakage scores were examined using a stereomicroscope at the 30x magnification after each sample was stained with 0.5% basic fuchsin. The data were analyzed using Kruskall Wallis and Mann Whitney U tests (P=0.05). RESULTS: Aqua-Prep F samples showed significantly higher microleakage scores at the enamel margins than did the Hemaseal & Cide and control groups (P<.05). Hemaseal & Cide application led to less microleakage than the other groups both at the enamel and dentin margins (P<.05). CONCLUSIONS: Hemaseal & Cide desensitizer decreased the microleakage process at the enamel and dentin margins of inlay restorations luted with adhesive luting cement, while Aqua-Prep F increased the leakage scores at the enamel margins.

One-year clinical evaluation of the efficacy of a new daytime at-home bleaching technique.

The aim of this study was to compare the clinical efficacy and side effects of a new daytime at-home bleaching technique (28% carbamide peroxide [CP] gel) with the overnight application of 10% CP and to determine the change of tooth color 1-year post-treatment. Twenty healthy volunteers were assigned to one of two sample groups of 10. All participants employed one of the two at-home bleaching systems: (1) the new daytime at-home bleaching system including 28% CP gel with a non-custom-fit tray (Meta Tray, Remedent, Deurle, Belgium) for 20 minutes, and (b) the conventional overnight at-home bleaching system with a 10% CP gel and a custom-fit tray (Opalescence PF, Ultradent, South Jordan, UT, USA) for 6 to 8 hours. Digital images and CIE (International Commission on Illumination) L*, a*, and b* spectrophotometric measurements were taken at baseline, after the bleaching treatment and 1-year post-treatment. Tooth and gingival sensitivity was measured with a specially designed 4-point scale. Significant differences were found in L*, a*, and b* values, between initial and post-treatment, for both bleaching systems (p < 0.05). However, no significant difference was detected between post-treatment and 1-year follow-up. The bleaching effectiveness of Opalescence PF was found to be superior to that of Meta Tray, considering the color parameter of DeltaE (p < 0.05). Meta Tray provoked less tooth sensitivity (p < 0.05), however gingival sensitivity appeared more in this group (p < 0.05). Within the limitations of this study, it can be concluded that the new daytime at-home bleaching system tested (Meta Tray) produced significant bleaching effects. However, the clinical efficacy of the overnight bleaching system was found to be superior to the daytime at-home bleaching system evaluated in this study. The whitening effect remained similar 1-year after the bleaching treatment for both at-home bleaching systems. CLINICAL SIGNIFICANCE Although the new daytime at-home bleaching system tested exhibited significant bleaching effects, overnight bleaching with a 10% CP gel resulted in a higher bleaching effectiveness than this new system. Although the participants using the new bleaching system exhibited less tooth sensitivity probably because of the reduced contact time of bleaching gel with tooth surfaces, the application of the bleaching agent with a non-customized tray provoked more gingival sensitivity in this group.

Reversal of reduced bond strength after bleaching.

This article investigated how the shear bond strength of a luting resin to dentin was affected by antioxidant treatment and delayed bonding after bleaching with carbamide peroxide. Using a lowspeed diamond saw, 40 flat dentin surfaces were prepared from freshly extracted human molars and divided into three bleaching groups (n = 10) and a control group (n = 10). Group 1 consisted of specimens bonded immediately after bleaching. Group 2 specimens were treated with an antioxidant agent (10% sodium ascorbate), while Group 3 specimens were immersed in artificial saliva for one week after bleaching. Specimens in Group 4 were not bleached but were immersed in artificial saliva for one week before bonding. Forty ceramic blocks were prepared and luted to teeth using a dual-curing resin cement. The specimens were thermocycled and the shear bond strength tests were performed using a universal testing machine. Fracture analysis was performed using a scanning electron microscope. While the Group 1 samples demonstrated the lowest shear bond strengths (11.9 +/- 3 MPa) (p < 0.05), no significant differences were found among samples in Group 2 (26.3 +/- 7.1 MPa), Group 3 (20.7 +/- 6.5 MPa), and Group 4 (22.1 +/- 2.5 MPa) (p = 0.05).

Influence of fluoride- or triclosan-based desensitizing agents on adhesion of resin cements to dentin.

Effect of desensitizers on the bond strength of resin cements to dentin was evaluated. Intact premolars (N = 90) were embedded in polymethyl methacrylate; dentin surfaces were exposed, and they were randomly divided into two main groups of cements (Duolink (D), Variolink II (V); n = 45 per group) and then into three desensitizer subgroups (n = 15 per subgroup). Teeth in controls (C) were treated according to cements' adhesion protocols; the other two groups received either fluoride- [Aqua-Prep F (F)] or triclosan-based [Seal&Protect (T)] desensitizers. Ceramic disks (Empress 2) were adhered; specimens were thermocycled (×5,000 cycles, 5-55 ± 1°C, dwell time 30 s) and subjected to shear bond strength test (MPa ± SD) in a universal testing machine (crosshead speed 1 mm/min). Failure types were classified using scanning electron microscope. For V, application of both desensitizers (29.6 ± 7.8 and 22.8 ± 2.8 for F and T, respectively) did not present significantly different results than that of the VC (21.2 ± 2.3; p > 0.05, one-way ANOVA). In D, F (20.6 ± 2.4) showed significantly higher results (p < 0.05) than those in T (16.1 ± 3.9) and DC group (15.2 ± 2.3). V showed significantly higher results than D (p < 0.05, Bonferroni). F and T did not negatively affect the bond strength results with D and V. Adhesive failures were more frequent with both T (84%) and F (66%) in D; cohesive failures in the cement (88%) were more commonly observed with F in V. Both F and T desensitizers can be safely used prior to final cementation but F in combination with V seems to be more reliable, considering both the bond strength and the failure types.

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.

Effects of glass fiber layering on the flexural strength of microfill and hybrid composites.

STATEMENT OF THE PROBLEM: In stress-bearing cavities, low fracture resistance adversely affects the longevity of the dental resin composite restorations. PURPOSE: The aim of this in vitro study was to investigate the effect of glass fiber layering on the flexural strength of microfill and hybrid composites. MATERIALS AND METHODS: Flexural test specimens (N = 75) were prepared according to International Organization for Standardization (ISO) 4049 specifications (25 x 2 x 2 mm) by using a standard metallic mold. Materials used and groups were as follows (N = 15): group 1: hybrid composite (Clearfil APX, Kuraray Co.Ltd, Osaka, Japan); group 2: microfill composite (Clearfil ST, Kuraray Co.Ltd.); group 3: hybrid + microfill composite; group 4: woven glass fiber (EverstickNet, StickTech Ltd, Turku, Finland) + hybrid composite; group 5: woven glass fiber + microfill composite. The specimens were stored in distilled water at 37 degrees C for 7 days. Afterward, they were loaded to fracture (1 mm/min) by using a universal testing machine (AG-50 kNG Shimadzu Co., Kyoto, Japan). Flexural strengths were expressed as maximum flexural load per cross-sectional area of the specimen. The results were statistically analyzed with Kruskall-Wallis and Mann-Whitney U tests (p < 0.01). RESULTS: Significant increases in the flexural strength were found for both hybrid and microfill composites when fiber layering was used (group 1: 78 +/- 7 MPa; group 4: 93 +/- 4 MPa) (group 2: 42 +/- 5 MPa; group 5: 64 +/- 4 MPa) (p < 0.01). Flexural strength of fiber-reinforced hybrid composite was significantly higher than the other groups evaluated (p < 0.01). There were no significant differences in flexural strength between microfill/hybrid combination and fiber-reinforced microfill composite (p > 0.01). CONCLUSIONS: Glass fiber layering of microfill and hybrid composites presented higher flexural strength, and veneering of hybrid composite with microfill composite increased the resistance of the restoration.

Can the hydrogel form of sodium ascorbate be used to reverse compromised bond strength after bleaching?

PURPOSE: To assess the effect of the hydrogel form of different concentrations (2.5%, 5%, and 10%) of sodium ascorbate on the shear bond strength of composite after bleaching of the enamel with 10% carbamide peroxide gel. MATERIALS AND METHODS: Sixty flat buccal enamel surfaces obtained from 30 bovine incisors were divided into 6 treatment groups: group I, control (nonbleached); group II, no antioxidant treatment after bleaching; group III, 10% sodium ascorbate solution after bleaching; group IV, 2.5% sodium ascorbate hydrogel after bleaching; group V, 5% sodium ascorbate hydrogel after bleaching; group VI, 10% sodium ascorbate hydrogel after bleaching. The specimens were bonded with Clearfil SE Bond, then thermocycled and subjected to the shear test until failure. Fracture analysis of the bonded enamel surfaces was examined using a stereomicroscope. Statistical analysis was carried out using Kruskal-Wallis and the Mann-Whitney U-test. RESULTS: While the samples that were not treated with antioxidant after bleaching (group I) demonstrated significantly lower shear bond strengths and the 10% sodium ascorbate gel group (group VI) demonstrated significantly higher bond strengths than the control group (p < 0.05), no significant differences were found between the other groups and control group (p > 0.05). Among the antioxidant groups, only the groups treated with the 10% solution and the 10% hydrogel form of sodium ascorbate (group III and VI) revealed significantly higher bond strengths than the bleached group without antioxidant (group II) (p < 0.05). Higher scores were obtained with 10% sodium ascorbate gel (group VI) when compared with the other antioxidant-treated groups (p < 0.05). CONCLUSION: Within the limitations of this study, it can be concluded that the 10% hydrogel form of sodium ascorbate may be used in clinical procedures instead of its solution form. However, using sodium ascorbate hydrogel with concentrations lower than 10% may not be as reliable as using this agent in 10% concentration for reversing the compromised bond strength.

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.

Reversal of compromised bonding in bleached enamel using antioxidant gel.

Many studies have shown a considerable reduction in the enamel bond strength of resin composite restorations when the bonding procedure is carried out immediately after bleaching. These studies claim that a certain waiting period is needed prior to performing the restoration in order to attain the original bond strength values. This study determined the most effective time duration for the application of sodium ascorbate prepared in gel form. The labial surfaces of 70 bovine incisors were polished with 600-grit silicon carbide paper on a water-irrigated metallurgical polishing wheel. The specimens were randomly divided into seven groups: 1) bleaching (10% Rembrandt Xtra-Comfort +) immersed in artificial saliva for seven days, 2) bonded immediately after bleaching, 3) bleaching + 10% sodium ascorbate (SA) gel for 10 minutes, 4) bleaching + 10% SA gel for 60 minutes, 5) bleaching + 10% SA gel for 120 minutes, 6) bleaching + 10% SA gel for 240 minutes and 7) bleaching + 10% SA gel for 480 minutes. After preparation, a standard-shaped resin composite was applied to all specimens. The teeth were stored in distilled water at 37 degrees C for 24 hours and a universal testing machine determined their shear bond strength. The data were evaluated using ANOVA and Tukey tests. Antioxidant gel proved to be effective for increasing the shear bond strength of the resin composite to enamel. For maximum effectiveness, antioxidant gel should be applied to enamel for at least 60 minutes. As the application period of the antioxidant increased, the bond strength of the composite on enamel tissue also increased. The increase noticed in Groups 5, 6 and 7 was statistically significant (p<0.05). Application of the antioxidant gel by the patient shortens the time spent in the clinic.

Effect of antioxidant treatment on bond strength of a luting resin to bleached enamel.

PURPOSE: The aim of this study was to comparatively investigate the effect of antioxidant treatment and delayed bonding after bleaching with carbamide peroxide on the shear bond strength (SBS) of a luting resin to enamel. MATERIALS AND METHODS: Forty flat enamel surfaces were prepared from freshly extracted human molars using a low speed diamond saw, then divided into three bleaching groups (n=10/group) and a control group (n=10). Group 1 consisted of specimens bonded immediately after bleaching. Group 2 specimens were treated with an antioxidant agent, 10% sodium ascorbate, while Group 3 specimens were immersed in artificial saliva for 1 week after bleaching. Specimens in Group 4 were not bleached, but immersed in artificial saliva for 1 week before bonding. Forty ceramic blocks (Empress 2, Ivoclar) were prepared and luted to teeth using a dual-curing resin cement (Variolink II, Ivoclar). The specimens were thermocycled and the SBS tests were performed using a universal testing machine (crosshead speed: 0.5mm/min). Fracture analysis of the bonded surfaces was done using a scanning electron microscope. Statistical analysis was carried out by Kruskall-Wallis and Mann-Whitney U-tests. RESULTS: While the samples that were immediately bonded after bleaching (Group I) demonstrated significantly lower shear bond strengths and 10% sodium ascorbate group (Group II) demonstrated significantly higher bond strengths than control group samples (p<0.05), no significant differences were found among delayed bonded group and control group (p>0.05). CONCLUSION: Using sodium ascorbate with a concentration of 10% may be reliable for reversing the compromised bond strength.

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.

Bond strength of glass-ceramics on the fluorosed enamel surfaces.

OBJECTIVES: Effect of different adhesive luting systems on the shear bond strength of IPS Empress 2 ceramic restorations to fluorosed enamel surface was investigated. METHODS: Forty-eight ceramic discs (2 mm x 3 mm; IPS Empress 2) were fabricated. Twenty-four non-carious extracted human molar teeth with fluorosis and 24 without fluorosis were cleaned with pumice using a plastic brush and then they were divided into two main groups. The IPS Empress 2 ceramic discs were luted to the teeth of four subgroups with two different adhesive luting systems, Variolink 2/Excite DSC (etch-and-rinse) and Clearfil Esthetic Cement/ED Primer II (self-etch), thermocycling was performed 5000 times. Shear bond strengths were tested using Shimadzu Universal Testing Machine until failure. An optical microscope and image analyzer were used at 10x and 1000x magnification to analyze the surfaces for adhesive, cohesive and mixed failure percentages. Data was analyzed with one-way ANOVA and Tukey test at a significance level of p<0.05. RESULTS: Mean shear bond strength data of the groups in MPa were; Variolink 2/Excite DSC on fluorosed enamel: 18.3+/-3.08, Variolink 2/Excite DSC on non-fluorosed enamel: 18.79+/-2.65, Clearfil Esthetic Cement/ED Primer II on fluorosed enamel: 8.43+/-2.45, Clearfil Esthetic Cement/ED Primer II on non-fluorosed enamel: 13.53+/-1.68. Mixed failure was the most prevalent type of failure in moderate fluorosed and non-fluorosed teeth with etch-and-rinse dentin bonding system, and in fluorosed teeth with self-etch dentin bonding system. CONCLUSIONS: The use of an etch-and-rinse adhesive luting procedure produced higher bond strengths of glass-ceramics bonded to fluorosed and non-fluorosed enamel surfaces than the self-etch bonding system.

Can different chlorhexidine agents be used as cavity disinfectants?

This study used the agar well method to compare the antimicrobial effect of cavity disinfectants containing chlorhexidine with other chlorhexidine agents (such as mouthrinses and antiseptics) and to determine whether there was a difference in composite bond strength when these chlorhexidine agents were applied to the dentin surface. All tested solutions showed antimicrobial effect against Streptococcus mutans, Lactobacillus acidophilus, and Candida albicans (p < 0.05). However, Savlex was found to be the most effective antibacterial agent against all microorganisms (p < 0.05). There were no significant differences between the bond strengths obtained from the cavity disinfectants and those of the control group (p > 0.05). However, the mouthrinse and the antiseptic decreased the shear bond strength compared with the control group (p < 0.05).