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Aim: This in vitro study evaluates the influence of marginal sealing methods in composite restorations with different adhesive systems submitted to mechanical load. Materials and Methods: Eighty bovine incisor crowns were embedded in Polyvinyl chloride (PVC) molds with the buccal surface exposed, where cavities (4mm x 4mm x 3mm) were made. Samples had the adhesive systems, Single Bond or Clearfil SE Bond, applied according to the manufacturer′s recommendations. The cavities were filled with a Z-250 composite according to the restoration technique (bulk filling or three increments) and photoactivation (conventional, soft start, pulsatile light or light-emitting diode [LED]). The samples were duplicated with epoxy resin for scanning electron microscopy observations. Samples were also submitted to mechanical load (200,000 cycles; 2 Hz) and new replicas were made. Results: The results, in percentages, were submitted to ANOVA followed by Tukey′s test (P < 0.05). There was statistical difference between the cycle group (23.84%) and the non cycle group (18.63%). Comparing the restoration technique, there was no statistical difference between bulk filling (19.62%) and three increments (22.84%). There was no statistical difference among the groups: Pulsatile light (24.38%), soft start (22.75%), LED (21.47%) or conventional (16.34%). Furthermore, there were no statistical differences between the adhesive systems: Clearfil SE Bond (21.32%) and Single Bond (20.83%). Conclusions: The photoactivation methods, the restorative techniques and the adhesive systems did not influence gap formation.

Aim: To evaluate the influence of quartz tungsten halogen and plasma arc curing (PAC) lights on Knoop hardness and change in polymerization temperature of resin composite. Materials and Methods: Filtek Z250 and Esthet X composites were used in the shade A3. The temperature increase was registered with Type-k thermocouple connected to a digital thermometer (Iopetherm 46). A self-cured polymerized acrylic resin base was built in order to guide the thermocouple and to support the dentin disk of 1.0 mm thickness obtained from bovine tooth. On the acrylic resin base, elastomer mold of 2.0 mm was adapted. The temperature increase was measured after composite light curing. After 24 h, the specimens were submitted to Knoop hardness test (HMV-2000, Shimadzu, Tokyo, Japan). Data were submitted to ANOVA and Tukey′s test (a = 0.05). Results: For both composites, there were no significant differences (P > 0.05) in the top surface hardness; however, PAC promoted statistically lower (P < 0.05) Knoop hardness number values in the bottom. The mean temperature increase showed no significant statistical differences (P > 0.05). Conclusion: The standardized radiant exposure showed no influence on the temperature increase of the composite, however, showed significant effect on hardness values.

The purpose of this study was to evaluate the effects of storage (1 day, 3 months and 6 months) on the shear bond strength of five adhesive systems on bovine dentin substrate. One hundred and fifty bovine incisors were flattened until areas of a minimum of 5 mm in diameter were exposed. A round area of 4 mm in diameter was marked on the dentin to be treated with the following adhesive systems: Clearfil Liner Bond 2V (CLB2V), Scotchbond Multi Purpose Plus (SBMP), Optibond Solo (SOLO), Prime & Bond NT (PBNT) and Etch & Prime 3.0 (E&P). To perform the test, a composite restoration (Z100) was made in a cylindrical shape on the treated surface. After the storage period in distilled water at 37ºC, the samples were tested on an Instron testing machine. Results were submitted to ANOVA and Tukey's test at 5% significance level. SBMP, PBNT and E&P were statistically similar at all storage times (p>0.05). CLB2V demonstrated the highest mean shear bond strength at 3 months which was not significantly different at 6 months (p>0.05). In addition, CLB2V had the highest means at all times tested. SOLO had the lowest mean shear bond strength at 6 months, which was statistically lower than means at 3 months and 1 day (p

The relationship between metallic cast crowns and tensile strength according to cement types submitted to thermocycling was studied. Seventy-two metallic crowns were cast with Verabond II Ni-Cr alloy and cemented in standardized preparations with 10º tapering. Three types of finishing line (45-degree chamfered, 20-degree bevel shoulder and right shoulder) were made with diamond burs on bovine teeth. Twenty-four metallic crowns in each group were randomly subdivided into three subgroups of 8 samples each according to the cement used: SS White zinc phosphate cement, Vitremer resin-modified glass ionomer cement, and Rely X resin cement and were submitted to thermocycling. Retention was evaluated according to tensile load required to displace the metallic cast crowns from tooth preparations with an Instron testing machine. ANOVA and Tukey's test showed a statistically significant difference among luting materials, with greater results for Rely X resin cement (24.9 kgf) followed by SS White zinc phosphate cement (13.3 kgf) and Vitremer resin-modified glass ionomer cement (10.1 kgf). The finishing line types did not influence the tensile resistance of the crowns fixed with the three cements. Increased tensile resistance of metallic crowns fixed on bovine teeth was obtained with resin cement, independent of the finishing line types.

Objectives : The objective of the present study was to evaluate in vitro film thickness of two endodontic sealers containing epoxy-resin and zinc-oxide-eugenol, respectively in the apical region of the root canal system. Materials and Methods : A total of 20 palatine roots of the first maxillary molars were submitted to instrumentation up to a #40 file by the step-back technique and irrigated with 2 ml of NaOCl after each change of file. The roots were divided at random into two groups of 10 elements; one group was sealed with the Sealer 26® cement and the other one with the EndoFill® cement using the classical technique. The roots were abraded in the apical region until exposure of the filling and cut crosswise at 3 mm to obtain samples. The samples were analyzed by optic microscopy with 40X magnification. The images obtained were recorded using the Adobe Premiere 5.1® software and submitted to morphometric analysis using an integration grid that permitted the quantification of the area filled with the sealer or gutta-percha, and eventual empty spaces. Results : Statistical analysis of the data (Kruskal-Wallis test, P < 0.05) revealed no significant differences between the epoxy-resin-based cement Sealer 26® (47.85%) and the zinc- oxide- eugenol-based cement EndoFill® (54.16%). Conclusion : We conclude that the two sealers tested showed a similar behavior regarding the cement film thickness in the apical region.

Objective: This study evaluated the efficiency of repolishing, sealing with surface sealant, and the joining of both in decreasing the surface roughness of resin-based composites after a toothbrushing process. Method and Materials: Ten specimens of each composite (Alert, Z100, Definite, and Prodigy Condensable), measuring 2 mm in thickness and 4 mm in diameter, were made and submitted to finishing and polishing processes on both sides of the specimens using the Sof-Lex system. The specimens were then subjected to tooth-brushing (30,000 cycles), and surface roughness (Ra) was analyzed with a Surfcorder SE 1700 profilometer. The upper surface of each composite was etched with 37% phosphoric acid, and the surface-penetrating sealant Protect-it was applied on 1 surface. The roughness of these surfaces was again measured. On the other side, the surface of the specimen was repolished, and the efficiency of this procedure was measured using the profilometer. The surface roughness resulting from the joining of the 2 methods was verified by applying, in the final stage, the surface-penetrating sealant on the repolished surface. Data were analyzed with analysis of variance and Tukey test (P < .05). Results: Results showed that the lowest surface roughness values were obtained for Definite, Z100, and Prodigy Condensable after the repolishing process and after the repolishing plus sealing. For Alert, the joining of repolishing plus sealing promoted the lowest values of surface roughness. Conclusion: Of the resin-based composites, Alert demonstrated the highest values of surface roughness in all the techniques tested. [ABSTRACT FROM AUTHOR]

Purpose: The objective of this study was to verify the effect of cyclic compressive loading on the shear bond strength of an adhesive system following collagen removal. Materials and Methods: Sixty bovine teeth were divided into 4 groups based on the adhesive procedure used: groups 1 and 2 - etching with 35% phosphoric acid and application of the Single Bond adhesive system; groups 3 and 4 - after etching, a 10% sodium hypochlorite solution was applied for 1 min before the application of the adhesive. In all the specimens, a Z100 resin cylinder was built up over the bond area. Groups 2 and 4 were submitted to 500,000 cycles with a load of 100 N. Results: The mean values for the shear bond test (MPa) were: group 1: 7.37 ± 1.15; group 2: 5.72 ± 1.66; group 3: 5.95 ± 1.21; group 4: 3.66 ± 1.12. There was no difference between groups 1 and 2 (p > 0.01). Between groups 1 and 3, 2 and 4, and 3 and 4 there was a significant difference (p < 0.01). The majority of the specimens demonstrated an adhesive failure. Conclusion: The application of sodium hypochlorite on dentin decreased the values of shear bond strength, as did the load cycling in the group treated with sodium hypochlorite. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate the effect of sodium hypochlorite (NaOCl) on the shear bond strength (SBS) using three bonding systems in primary dentin. Materials and Methods: Forty-five sound extracted primary molars were selected. The crowns were longitudinally sectioned, embedded in polystyrene resin, and flattened until a dentin surface was reached. The samples were assigned to 6 groups (n = 15): G1, Single Bond (SB); G2, NaOCl + SB; G3, Prime & Bond 2.1 (PB); G4, NaOCl + PB; G5, Clearfil SE Bond (CSE); G6, NaOCl + CSE. All the adhesive systems were applied according to the manufacturers' instructions, except for the application of 10% NaOCl solution for 60 s in groups 2, 4 (after acid etching), and 6 (before applying adhesive system). The composite resin was placed in increments in a mold and light cured for 20 s. The samples were stored in distilled water at 37°C for 24 h and submitted to SBS testing with a crosshead speed of 0.5 mm/min. The failure sites were observed with SEM. The data were treated with ANOVA and Tukey's tests (p < 0.05). Results: There was no statistically significant difference between the groups with or without treatment of the substrate with NaOCl, regardless the material used. The SBS averages in MPa (± SD) were: G1: 15.8(1.9)a; G2: 14.6(1.3)a; G3: 10.2(0.7)a; G4: 9.9(0.2)a; G5: 13.3(1.2)a; and G6: 10.7(1.0)a. There was a statistically significant difference between the materials (SB ≥ CSE ≥ PB). Mixed failure was the failure type most frequently observed for all groups. Conclusion: Dentin surface treatment with NaOCl did not affect the resin-dentin bonding strength in primary teeth. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate the effect of different ceramic surface treatments on the tensile bond strength between IPS Empress 2 ceramic framework and Rely X adhesive resin cement, with or without the application of a silane coupling agent. Materials and Methods: One hundred twenty disks were made, embedded in resin, and randomly divided into six groups: group 1 = sandblasting (100 µm), no silanation; group 2 = sandblasting (100 µm), silane treatment; group 3 = sandblasting (50 µm), no silanation; group 4 = sandblasting (50 µm), silane treatment; group 5 = hydrofluoric acid etching, no silanation; and group 6 = hydrofluoric acid etching, silane treatment. The disks were bonded into pairs with adhesive resin cement. All samples were stored in distilled water at 37°C for 24 hours and then thermocycled. The samples were submitted to tensile testing. Results: The use of silane improved the bond strength in relation to the groups in which silane was not applied (P < .05). The most effective surface treatment was etching with 10% hydrofluoric acid, both with (25.6 MPa) and without silane application (16.4 MPa); these values showed a statistically significant difference compared to sandblasting with 50- and 100-µm Al2O3. Sandblasting with 50-µm Al2O3, with (11.8 MPa) and without silane (5.4 MPa), demonstrated significantly higher tensile bond strength than sandblasting with 100-µm Al2O3, with (8.3 MPa) and without silane (3.8 MPa). Conclusion: Combined application of 10% hydrofluoric acid and silane enhanced the bond strength between the IPS Empress 2 ceramic framework and resin agent. [ABSTRACT FROM AUTHOR]

Aim: The aim of this study was to verify the effect of the occlusal contact of the rod tip on the fracture strength of crowns made with different ceramic systems. Materials and Methods: Conical preparation was performed on bovine teeth with diamond burs in mechanical lathe, and crowns were made for all-ceramic, metal-ceramic, In Ceram, and IPS Empress 2 ceramic systems according to manufacturers' instructions in prosthetic laboratory. The crowns were fixed with resin-modified glass ionomer cement or dual-curing composite resin under a static load of 4 kg for 1 min. To simulate the clinical contact between loading and ceramic crowns, the rod tip was made in accordance with the occlusal form of the ceramic crown. After storage in distilled water at 37°C for 24 h, the samples were submitted to 60,000 mechanical cycles at a load of 35 N/2 Hz immersed in distilled water. The fracture strength test was performed in an Instron with a cross-speed of 0.5 mm/min. Results: Data submitted to one-way ANOVA for randomized experiments followed by Tukey's test (a = 0.05) showed greater value for IPS Empress 2 (208.12 kgf) with significant difference in relation to all-ceramic (149.32 kgf) and In Ceram (142.25 kgf), whereas metal-ceramic showed intermediary value (182.83 kgf). Conclusion: The loading of the rod tip in occlusal contact with the crown did not promote premature failures during the mechanical fatigue test, and two-ceramic systems showed different values of fracture strength after mechanical fatigue test, with better performance for crowns manufactured with IPS Empress 2. [ABSTRACT FROM AUTHOR]