The aim of this study was to evaluate physical-mechanical properties, degree of conversion, and chemical stability of a nanohybrid composite containing diatomite as filler. Degree of conversion (DC%) of diatomite-containing composite (Zirconfill®) was performed using FTIR immediately, and 1-, and 7-days post-curing. SEM was conducted to evaluate the surface of the resin after curing and measure particles size. Also, elemental characterization was performed to verify the major components of the composite through EDS. Mechanical characterization using 3-point bending test was performed prior and after thermo-cycling (10000 cycles) (n=10). Knoop microhardness (KHN) was used to characterize mechanical stability after chemical solutions aggression (water, juice, coffee, coke) up to 28 days (n=10/solution). After data normality evaluation using Shapiro-Wilk, One-way ANOVA and Tukey post hoc were conducted to verify differences between groups for DC% and mechanical properties. Split-plot ANOVA was used to compare groups for microhardness characterization (α=0.05). Immediate DC was 60% and significantly increased up to 80% at 7 days (p<0.05). Flexural strength of the diatomite-containing composite was 136.2 (23.7) MPa and significantly decreased to 75.1 (10.2) as a result of thermo-cycling. The flexural modulus was not significantly affected by the thermo-cycling (p>0.05). All the dietary solutions affected the KHN of the composite up to 21 days. For 28 days, the KHN evidenced and stabilization regarding all the solutions. Diatomite-containing composites present good degree of conversion and relevant mechanical properties and demonstrate time-dependent stability against chemical degradation.

Objectives: The aim of this study was to evaluate the effect of heated irrigating solutions on the cyclic fatigue resistance of reciprocating endodontic files. Materials and Methods: Reciproc Blue, ProDesign S and X1-Blue files were immersed in the irrigating solutions 5.25% NaClO and 2% chlorhexidine digluconate gel heated in oven at 37ºC for 10 min. In same conditions, saline solution was considered as control. The following groups (n=15) were considered: RSs (Reciproc Blue + saline solution); RNa (Reciproc Blue + 5.25% NaClO); RCd (Reciproc Blue + 2% Chlorhexidine digluconate gel); PSs (ProDesign S + saline solution); PNa (ProDesign S + 5.25% NaClO); PCd (ProDesign S + 2% Chlorhexidine digluconate gel; XSs (X1-Blue + Saline solution); XNa (X1-Blue + 5.25% NaClO) and XCd (X1 Blue + 2% Chlorhexidine digluconate gel). Cyclic fatigue test was performed in a device with a 60 degrees curved canal and 5 mm radius immersed in water at 37ºC. The time for file failure was recorded in seconds to calculate the number of cycles to fracture (NCF). Data were submitted to ANOVA followed by Tukey's test (α=0.05%) comparing split plots (SPSS 26.0). Results: There was no statistically significant difference for NCF between irrigating solutions and control in all file types. ProDesign S showed greater and significant difference when compared to Reciproc Blue and X1 Blue in all irrigating solutions and control. Conclusions: NCF value in each file type was not influenced by the solutions. Among file types, the NCF value was higher for ProDesign S and lower for X1-Blue in all solutions. Clinical Relevance: Heated irrigating solutions is not a relevant factor in relation to fracture resistance of reciprocating endodontic files; however, the fracture was influenced by the file types.

Aims: The aim of this study was to develop and characterize a temporary restorative material based on a zinc oxide matrix containing niobophosphate bioactive glass (NbG) for the caries-affected dentin treatment. Material and methods: NbG was added to a ZnO2 matrix in different concentrations (wt%). EDS-SEM, ATR-FTIR and XRD analyses were performed to characterize the cement. Calcium release was evaluated in TRIS solution after 1, 7 and 14 days by colorimetric method (A(650)). Compressive strengths and setting times were performed to analyze mechanical properties. Results: EDS spectra confirmed the presence of Ca, P and Nb in the groups containing NbG. EDS mapping exhibit the ZnO2 homogeneous distribution, and NbG immersed in this matrix. Peaks suggesting interaction between matrix and NbG were not detected in Ftir spectra. Calcium releasing showed to be time-dependent for experimental groups containing 10, 20, 30 and 40%. The NbG incorporation progressively increased the compressive strength values in the experimental groups. NbG incorporation seemed to influence the ZnO2 matrix early setting reaction. No statistical difference was observed in the final setting time. Conclusion: The addition of NbG particles into zinc oxide matrix could work as a mechanical reinforcement. It is suggested that the calcium released by the cement containing at least 10% NbG could induce apatite formation. (C) 2021 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University.

PURPOSE:To evaluate the effect of two desensitizing agents applied before in-office bleaching, on the degree of whitening and dentin sensitivity.METHODS:Participants were randomly assigned to the groups, according to the desensitizing agent used, with n=10 for each one. The bleaching was performed with 35% hydrogen peroxide, divided according to the desensitizing agent used prior to the bleaching procedure: Placebo (PL); Desensibilize KF with potassium nitrate and 0.2% sodium fluoride (PN); and Oxa-Gel with potassium oxalate (PO). The level of color saturation was assessed at the beginning of treatment and after 1 week of its completion by means of comparative method with the aid of a color scale. The degree of sensitivity (DS) was noted by the subjects with the aid of a visual scale throughout the time that the bleaching agent remained in contact with the teeth (5, 10, 15, 20, 25 and 30 minutes) as well as 1, 24 and 48 hours after the end of application. Pain and the degree of color saturation were evaluated using the Shapiro-Wilk test. The DS was assessed by Kruskal-Wallis and Dunn's tests. The color was evaluated by ANOVA and Tukey's HSD.RESULTS:There was no significant difference in the degree of bleaching among the groups. DS was significantly more accentuated in the 48-hour period. The DS was significantly higher for the PL group and significantly lower for the PO group. The desensitizing agents reduced the DS without affecting the effectiveness of the bleaching treatment.CLINICAL SIGNIFICANCE:Both desensitizing agents provided greater control over pain compared to the placebo group. Potassium oxalate showed greater pain control than potassium nitrate. Both desensitizing agents tested did not interfere in the degree of whitening.

Abstract The aim of this study was to evaluate the effect of different commercial silanes on microshear bond strength of resin cement to lithium disilicate ceramic. Twenty ceramic samples with 10 mm in length, 10 mm wide and 3 mm in thickness were fabricated, etched with 10% hydrofluoric acid for 20 seconds, and divided into 5 groups, according to the commercial silane applied: G1- RelyX Ceramic Primer (3M ESPE), G2- Angelus Silane, G3- Prosil (FGM), G4- Dentsply Silane (Dentsply) and G5- Bis-Silane (Bisco). Silanes were applied in accordance to manufacturers’ recommendations. Addition silicone molds with 1 mm in thickness, 10 mm in diameter and 3 perforations with 1 mm in diameter each one, were placed on ceramic and filled with the resin cement Rely X ARC (3M ESPE) in all groups. Light activation was performed with LED Bluephase G2 (Ivoclar Vivadent) at 1200 mW/cm2, for 30 seconds. Samples were maintained in 100% humidity at 37°C for 24 hours and submitted to microshear test. The data (MPa) were submitted to one-way ANOVA and Tukey test (α=0.05). The results obtained for each group were: G1: 22.39±2.99; G2: 23.35±4.08; G3: 26.05±5.46; G4: 18.56±4.09; G5: 25.26±4.10. Statistical analysis showed significantly lower microshear bond strength for G4. Fracture pattern analysis showed predominance of adhesive failures in G1 and G2. G3 and G5 presented higher percentage of cohesive failures in ceramic, and G4 showed mixed, adhesive and cohesive fractures with similar percentages. It was concluded that different silanes showed influence on the lithium disilicate ceramic – resin cement bond strength. Key Words: Silanes. Ceramics. Cementation. Shear strength.

Os autores avaliaram a resistência ao cisalhamento da união metal-cerâmica utilizando duas ligas não nobres, submetidas ou não à pré-oxidação antes da aplicação da porcelana. Dez barras cilíndricas de cada liga, medindo 30mm de comprimento por 2,5mm de diâmetro, foram fundidas pelo processo de cera perdida. Após o acabamento, cinco barras por liga foram submetidas à pré-oxidação recomendada pelos fabricantes. Em seguida, foram construídos discos de porcelana revestidos por discos de gesso especial, com 27mm de diâmetro por 12mm de altura. Após 24 horas, as amostras foram ensaiadas numa máquina de ensaio universal. A resistência ao cisalhamento das ligas pré-oxidadas foi estatisticamente diferente das ligas não pré-oxidadas, ao nível de 5% de significância.

OBJECTIVES:To evaluate the incorporation of doxycycline (DOX) into a commercial dental adhesive regarding physicochemical properties, microtensile bond strength (μTBS), nanoleakage (NL), nanohardness (NH) and Young's modulus (YM), metalloproteinases (MMP) inhibition, and antibiofilm activity. METHODS:DOX was incorporated into the adhesive at 0.05, 0.1, 0.5, and 1 wt%. Restored teeth were evaluated for μTBS, NL, NH, and YM after 24 -hs and 1-year of water storage. Biofilms of Streptococcus mutans were grown on top of these adhesives and determined for bacterial viability and amount of biomass. The inhibitory effect on MMP was analyzed by in situ zymography under confocal microscopy. RESULTS:Adhesives with 0.5 and 1 wt% of DOX presented reduced pH and degree of conversion. The incorporation of DOX did not affect μTBS and hybrid layer YM. The control group (no DOX) had a decrease in μTBS and the densest silver nitrate areas after 1-year storage. Hybrid layer NH values increased with 0.1 wt% DOX compared to control and 1 wt% DOX groups, at 24 -hs. After 1-year storage, NH of 1 wt% DOX adhesive decreased compared to the control group. The 0.5 and 1 wt% concentrations of DOX decreased the bacterial viability and the biofilm biomass. Confocal images suggest an increased MMP inhibition proportional to the percentage of DOX. CONCLUSION:At any concentration, DOX-doped dental adhesives were able to inhibit MMP activity, diminish nanoleakage, and maintain the resin-dentin bond-strength after 1 year of artificial aging. CLINICAL SIGNIFICANCE:Doxycycline-doped dental adhesive inhibited metalloproteinases activity and preserved interface bond strength. This formulation has a potential to improve adhesive restorations clinical longevity.

Abstract Objectives The aim of this study was to evaluate the bonding strength of self-adhesive luting cement to zirconia under different surface treatments. Materials and Methods Thirty-two zirconia samples were randomly divided into eight experimental groups based on the surface treatment employed (Control: no surface treatment; PMM: wear with diamond bur; JAT: blasting with glass beads; PMA: wear with a medium-roughness milling machine; Primer: primer application on the surface without treatment; PMM +Primer: PMM treatment plus primer application; JAT+Primer: JAT treatment plus primer application; and PMA+Primer: PMA treatment plus primer application). Cement cylinders were built on the ceramic surfaces, and the groups were subdivided according to the storage time employed (i.e., 24 hours or 60 days). After storage, the samples were subjected to microshear testing. Statistical Analysis The Kruskal–Wallis test followed by the Dunn test was employed for comparison between the groups (p < 0.05). Results The PMM group yielded the optimal results and the mean values increased after both storage times following the primer application. The Control, PMA, and JAT groups gave similar results after 24 hours, while the JAT group gave superior results following primer application over this storage time. After 60 days of storage, all groups gave improved results following chemical treatment with a primer. Conclusion It was concluded that mechanical preparation using the diamond bur followed by primer application significantly improved the bond strength between the ceramic and the luting cement.

The aim of this study was to evaluate Knoop hardness of different shades of a resin cement light-cured directly or through ceramic discs, measured 15 min or 24 h after light exposure, and at different depths. Specimens of a commercial resin cement (Variolink Veneer) in seven shades, were fabricated in an elastomeric mold, covered with a mylar strip, a 0.7 mm thick ceramic disc (IPS e.max Press) was placed and the cement was light-activated for 20 s using a blue LED (Radii-Cal). The cured resin cement specimens were transversely wet-flattened to their middle portion and microhardness (Knoop) values were recorded at 15 min after light exposure and after deionized water storage at 37 ºC for 24 h. Five indentations were made in the cross-sectional area at 100 and 700 μm depths from the top surface. Ten specimens were made for each test conditions. Data were submitted to ANOVA split-plot design (shade, post-cure time, mode of activation and depth), followed by Tukey post hoc test (α=0.05). Significant differences for shade (p<0.0001), mode of activation (p<0.001), post-cure time (p<0.0001) and depth (p<0.0001) were detected. No significant interactions (p>0.05) were found, except for shade x post-cure time (p<0.0045) and mode of activation x post-cure time (p<0.0003). Resin cement shade has a significant effect on Knoop hardness. Indirect activation through a ceramic material reduced significantly Knoop hardness. Hardness Knoop significantly increased after 24 h in all cements shades compared to values obtained after 15 min. Resin cement depth significantly reduced Knoop hardness.

OBJECTIVE:To evaluate the effects of dyphenyliodonium hexafluorophosphate (DPI) on crosslink density (CLD), flexural strength (FS), and flexural modulus (FM) of a light-cured experimental resin cement compared with a commercial dual-cured cement.MATERIALS AND METHODS:Bis-GMA combined with TEGDMA (50-50%) was used as resin matrix. Silanated barium-aluminum-silica glass was used as inorganic filler. Camphorquinone (CQ) - 1 mol%, 2-(dimethylamino)ethyl methacrylate (DMAEMA) - 2 mol%, and two concentrations of DPI (0 or 0.5 mol%) were used as the photoinitiator system. Two light-curing units (LCUs) were used (a single-peak (Radii-Cal) and a polywave (Bluephase)). The CLD was indirectly assessed in a softening test by Knoop hardness indentation; FS and FM were measured by means of a three-point bending test.RESULTS:DPI positively influenced Knoop hardness when compared with experimental resin without DPI. The flexural strength of experimental cements was lower than that found with Variolink II. The crosslinking density (obtained by reduction of Knoop hardness) of cement with 0.5% DPI was similar to that of dual - cured Variolink II.CONCLUSIONS:DPI showed an improvement in some of the properties tested but was inferior to the commercial dual-cured resin cement. The LCUs had no influence on the flexural strength of the resin cements.

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 (α = 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.

The aim of this study was to evaluate the efficacy of applying sonic energy on microtensile bond strength and microhardness after the restoration process. A total of 40 human third molars were extracted. Class II cavities were prepared and restored with composite SonicFill or Filtek Z350 XT with and without the application of sonic energy. After the teeth were stored in water for 24 h, the teeth were sectioned into sticks (1.0 mm2) and subjected to tensile testing. For a depth Knoop hardness test, the samples were cut and indentations were made sequentially from the surface of the samples to the bottom of the samples in three intervals of 1 mm each. The samples were then subjected to a load of 50 g for 10 s. The results from the tensile (factors: placement system and composite) and hardness (factors: placement system, composite and depth) tests were subjected to the Kolmogorov-Smirnov normality test, followed by analysis of variance and Tukey's test (5% significance). For the placement system factor, higher bond strength was observed for the cavities that were restored with sonic energy (p < 0.001). For depth Knoop hardness, the hardness at 1 mm depth was significantly greater than that at 3 mm depth just for the restorations with Filtek Z350 XT composite without the application of sonic energy. Therefore, the use of sonic energy during the restorative process improved bonding, yet it did not markedly affect the depth hardness for both composites.

The aims of this study were to evaluate the nanohardness and Young’s modulus of the adhesive-dentin interface and to correlate them with the microtensile bond strength (μTBS) after storage in water for 24 h and 6 months.

bond strength and microhardness after the restoration process. A total of 40 human third molars were extracted. Class II cavities were prepared and restored with composite SonicFill or Filtek Z350 XT with and without the application of sonic energy. After the teeth were stored in water for 24 h, the teeth were sectioned into sticks (1.0 mm2) and subjected to tensile testing. For a depth Knoop hardness test, the samples were cut and indentations were made sequentially from the surface of the samples to the bottom of the samples in three intervals of 1 mm each. The samples were then subjected to a load of 50 g for 10 s. The results from the tensile (factors: placement system and composite) and hardness (factors: placement system, composite and depth) tests were subjected to the Kolmogorov-Smirnov normality test, followed by analysis of variance and Tukey’s test (5% significance). For the placement system factor, higher bond strength was observed for the cavities that were restored with sonic energy (p < 0.001). For depth Knoop hardness, the hardness at 1 mm depth was significantly greater than that at 3 mm depth just for the restorations with Filtek Z350 XT composite without the application of sonic energy. Therefore, the use of sonic energy during the restorative process improved bonding, yet it did not markedly affect the depth hardness for both composites. Microtensile Bond Strength and Mic rohardnes s o f Compos i t e R e s i n R e s t o r a t i o n s U s i n g a Sonic-Resin Placement System