Comparison of Different Dentin Pretreatment Protocols on the Bond Strength of Glass Fiber Post Using Self-etching Adhesive

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Longitudinal evaluation of bond strength to enamel of dental adhesive systems associated with Nd:YAG laser

Objectives: This study evaluated the durability of bond strength to enamel using total-etch (Single Bond/SB) and self-etch (Clearfil SE Bond/CSEB) adhesives associated with neody-mium: yttrium-aluminu- garnet (Nd:YAG) laser irradiation through the uncured adhesives.Methods: Bovine incisors were worn to expose an area of enamel and were divided into four groups: group 1 (control) SB + polymerization; group 2 (control) CSEB + polymerization; group 3 (laser) - B + Nd:YAG laser (174.16 J/cm(2)) + polymerization; and group 4 (laser) CSEB + Nd:YAG (174.16 J/cm(2)) + polymerization. Blocks of composite were fabricated and stored for 24 hours or 12 months, sectioned into beams, and submitted to microtensile tests. Results were analyzed by three-way analysis of variance (ANOVA) (adhesive, technique, and storage time) and Tukey tests.Results: ANOVA revealed significant differences for adhesive 3 technique and technique 3 storage time (p<0.05). The mean values (MPa) for interaction adhesive x technique (standard deviation) were as follows: SB/control = 35.78 (6.04)a; SB/laser = 26.40 (7.25)b, CSEB/control = 26.32 (5.71)b, CSEB/laser = 23.90 (7.49)b. For interaction technique x storage time the mean values were as follows: control/24 hours = 32.58 (6.49)a; control/12 months = 29.52 (8.38)a; laser/24 hours = 29.37 (5.71)a; laser/12 months = 20.92 (6.5)b. Groups with the same letters showed no statistically significant differences.Conclusion: Scanning electron microscope analysis showed evident areas of micromorphological alterations in lased samples after 12 months of water storage. Nd: YAG laser irradiation of enamel through unpolymerized totaletch adhesive significantly reduced bond strength compared with the control. Bond strength decreased when enamel samples irradiated with Nd: YAG laser through unpolymerized adhesives were stored in water for 12 months.

Quantum confinement in hydrogen bond of DNA and RNA

The hydrogen bond is a fundamental ingredient to stabilize the DNA and RNA macromolecules. The main contribution of this work is to describe quantitatively this interaction as a consequence of the quantum confinement of the hydrogen. The results for the free and confined system are compared with experimental data. The formalism to compute the energy gap of the vibration motion used to identify the spectrum lines is the Variational Method allied to Supersymmetric Quantum Mechanics.

Influence of Insertion Techniques for Resin Cement and Mechanical Cycling on the Bond Strength Between Fiber Posts and Root Dentin

Purpose: To evaluate the effect of the insertion technique for resin cement and mechanical cycling on the bond strength between fiber posts and root dentin.Materials and Methods: Sixty-four single-rooted bovine teeth were endodontically prepared to receive glass-fiber posts. The insertion of cement into the root canal was performed using one of the following techniques: POS, insertion with the post; LEN, the use of a lentulo-type drill; EXP, insertion with a straight-tip explorer; or CEN, the use of a Centrix syringe. Half of the specimens were mechanically cycled. All specimens were sectioned into slices of 1.8 mm for the push-out test and 0.5 mm for analysis of the cement layer quality.Results: The insertion technique affected the interaction between factors (bond strength and mechanical cycling; p < 0.0001). Insertion of the Centrix syringe after mechanical cycling showed the highest bond values (13.6 +/- 3.2 MPa). Group-to-group comparisons for baseline and cycled conditions indicated that mechanical cycling significantly influenced the bond strength (p < 0.0001) of the POS and CEN groups. The quality of the cement layer did not differ between the techniques when evaluated in the middle (p = 0.0612) and cervical (p = 0.1119) regions, but did differ in the apical region (p = 0.0097), where the CEN group had better layer quality for the two conditions tested (baseline and cycled).Conclusion: The use of the Centrix syringe improved the homogeneity of the cement layer, reducing the defects in the layer and increasing adhesive strength values to dentin, even after mechanical cycling.

A critical evaluation of bond strength tests for the assessment of bonding to Y-TZP

Objectives. To compare three different designs for measuring the bond strength between Y-TZP ceramic and a composite material, before and after ceramic surface treatment, evaluating the influence of the size of the adhesive interface for each design.Methods. 'Macro'tensile, microtensile, 'macro'shear, microshear, 'macro'push-out, and micropush-out tests were carried out. Two Y-TZP surface treatments were evaluated: silanization (sil) and tribochemical silica coating (30 mu m silica-modified Al2O3 particles + silanization) (TBS). Failure mode analysis of tested samples was also performed. Results. Both the surface treatment and the size of the bonded interface significantly affected the results (p = 0.00). Regardless of the type of surface treatment, the microtensile and microshear tests had higher values than their equivalent "macro" tests. However, the push-out test showed the highest values for the "macro" test. The tensile tests showed the greatest variability in results. The tribochemical silica coating method significantly increased bond strength for all tests.Significance. Different test designs can change the outcome for Y-TZP/cement interfaces, in terms of mean values and reliability (variability). The 'micro'tests expressed higher bond strengths than their equivalent 'macro'tests, with the exception of the push-out test (macro > micro). (C) 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Influence of thicknesses of smear layer on the transdentinal cytotoxicity and bond strength of a resin-modified glass-ionomer cement

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of storage times on bond strength of resin cements to root canal

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Evaluation of the shear bond strength of the union between two CoCr-alloys and a dental ceramic

Introduction: Based on the importance of the integrity of the metal/ceramic interface, the purpose of this work was to evaluate the shear bond strength of the metal-ceramic union of two Co-Cr alloys (Wirobond C, Bego; Remanium 2000, Dentaurum) combined with Omega 900 ceramic (Vita Zahnfabrik). Material and Method: Eleven cylindrical matrixes were made for each alloy, and the metallic portion was obtained with the lost wax casting technique with standardized waxing of 4mm of height and of 4mm of diameter. The ceramic was applied according to the manufacturer's recommendations with the aid of a teflon matrix that allowed its dimension to be standardized in the same size as the metallic portion. The specimens were submitted to the shear bond test in an universal testing machine (EMIC), with the aid of a device developed for such intention, and constant speed of 0.5mm/min. Results and Conclusions: The mean resistance was 48.387MPa for Wirobond C alloy, with standard deviation of 17.718, and 55.956MPa for Remanium 2000, with standard deviation of 17.198. No statistically significant difference was observed between the shear strength of the two metal-ceramic alloys.

Study of thermocycling effect on the bond strength between an aluminous ceramic and a resin cement

This study evaluated the effect of thermocycling on the bond strength between Procera AllCeram (Nobel-Biocare) and a resin cement (Panavia F, Kuraray CO). Nine ceramic blocks with dimensions of 5x6x6mm were conditioned at one face with Rocatec System (Espe). After, they were luted with Panavia F to composite resin blocks (Clearfil AP-X, Kuraray CO). The nine groups formed by ceramic, cement and composite resin were split up obtaining 75 samples with dimensions of 12x1x1mm and adhesive surface presenting 1mm2±0.1mm2 of area. The samples were divided into 3 groups (n=25): G1 - 14 days in distilled water at 37ºC; G2 – 6,000 cycles in water (5ºC - 55ºC – 30s); G3 – 12,000 cycles in water (5ºC - 55ºC – 30s). The samples were tested in a universal testing machine (EMIC) at a crosshead speed of 1mm/min. Data were analyzed by ANOVA and Tukey tests. The results indicated that mean values of rupture tension (MPa) of G1 (10.71 ± 3.54) did not differ statistically (p <5%) from G2 (9.01 ± 3.90), however there was statistical difference between G1 and G3 (7.28 ± 3.00). It was concluded that thermocycling significantly reduced the bond strength values when samples were submitted to 12,000 cycles.

Multi-step adhesive cementation versus one-step adhesive cementation: push-out bond strength between fiber post and root dentin before and after mechanical cycling

This study evaluated the effects of mechanical cycling on resin push-out bond strength to root dentin, using two strategies for fiber post cementation. Forty bovine roots were embedded in acrylic resin after root canal preparation using a custom drill of the fiber post system. The fiber posts were cemented into root canals using two different strategies (N = 20): a conventional adhesive approach using a three-step etch-and-rinse adhesive system combined with a conventional resin cement (ScotchBond Multi Purpose Plus + RelyX ARC ), or a simplified adhesive approach using a self-adhesive resin cement (RelyX U100). The core was built up with composite resin and half of the specimens from each cementation strategy were submitted to mechanical cycling (45 degree angle; 37 degrees C; 88 N; 4 Hz; 700,000 cycles). Each specimen was cross-sectioned and the disk specimens were pushed-out. The means from every group (n = 10) were statistically analyzed using a two-way ANOVA and a Tukey test (P = 0.05). The cementation strategy affected the push-out results (P < 0.001), while mechanical cycling did not (P = 0.3716). The simplified approach (a self-adhesive resin cement) had better bond performance despite the conditioning. The self-adhesive resin cement appears to be a good option for post cementation. Further trials are needed to confirm these results.

Influence of Nd:YAG or Er:YAG laser surface treatment on microtensile bond strength of indirect resin composites to resin cement. Lasers surface treatment of indirect resin composites

This study evaluated the influence of the surface pretreatment of indirect resin composite (Signum, Admira Lab and Sinfony) on the microtensile bond strength of a resin cement. Sixty samples made of each brand were divided into 6 groups, according to surface treatment: (1) control; (2) controlled-air abrasion with Al2O3; (3) Er:YAG Laser 200 mJ, 10 Hz, for 10s; (4) Er: YAG Laser 300 mJ, 10 Hz, for 10 s; (5) Nd:YAG 80 mJ, S15Hz for 1 min; (6) Nd:YAG 120mJ, 15 Hz for 1 min. After treatments, all the groups received an application of 37% phosphoric acid and adhesive. The pair of blocks of the same brand were cemented to each other with dual resin cement. The blocks were sectioned to obtain resin-resin sticks (1 x1 mm) and analyzed by microtensile bond testing. The bond strength values were statistically different, irrespective of the surface treatment performed, with highest values for Sinfony (43.81 MPa) and lowest values for Signum (32.33 MPA). The groups treated with the Nd:YAG laser showed the lowest bond strength values and power did not interfere in the results, both for Nd:YAG laser and Er:YAG. Controlled-air abrasion with Al203 is an efficient surface treatment method and the use of the Nd:YAG and Er:YAG lasers reduced bond strength, irrespective of the intensity of energy used.

Dentin bond strength: influence of Er:YAG and Nd:YAG lasers

The aim of this study was to investigate the effects of Er:YAG and Nd:YAG lasers on the shear bond strength of composite resin to dentin. The coronal portion of 56 human molars was divided into three parts, and the dentin thickness was standardized at 2 mm. A 3-mm hole was marked in the center of each tooth with sealing tape paper. The specimens (n = 14) were then divided into four groups: (1) acid etching + Single Bond (SB) (control), (2) acid etching + SB + Nd:YAG laser irradiation (before adhesive curing), (3) thermal etching with the Er:YAG laser + SB, and (4) thermal etching with the Er:YAG laser + SB + Nd:YAG laser irradiation (before adhesive curing). A composite resin cylinder was built into the delimited area for conducting the shear bond strength test on the universal testing machine. The means ± standard deviations were: group 1, 17.05 ± 4.15 MPa; group 2, 16.90 ± 3.36 MPa; group 3, 12.12 ± 3.85 MPa; and group 4, 12.92 ± 2.73 MPa. Groups 1 and 2 presented significantly higher values than groups 3 and 4. It was concluded that conventional etching with 37% phosphoric acid yielded significantly higher bond strength values compared to thermal etching with the Er:YAG laser. The Nd:YAG laser did not significantly influence the bond strength.

Escherichia coli strains isolated from the uteri horn, mouth, and rectum of bitches suffering from pyometra: virulence factors, antimicrobial susceptibilities, and clonal relationships among strains

Pyometra is recognized as one of the main causes of disease and death in the bitch, and Escherichia coli is the major pathogen associated with this disease. In this study, 70 E. coli isolates from the uteri horn, mouth, and rectum of bitches suffering from the disease and 43 E. coli isolates from the rectum of clinically healthy bitches were examined for the presence of uropathogenic virulence genes and susceptibility to antimicrobial drugs. DNA profiles of isolates from uteri horn and mouth in bitches with pyometra were compared by REP, ERIC, and BOX-PCR. Virulence gene frequencies detected in isolates from canine pyometra were as follows: 95.7% fim, 27.1% iss, 25.7% hly, 18.5% iuc, and 17.1% usp. Predominant resistance was determined for cephalothin, ampicillin, and nalidixic acid among the isolates from all sites examined. Multidrug resistance was found on ∼ 50% pyometra isolates. Using the genotypic methods some isolates from uteri, pus, and saliva of the same bitch proved to have identical DNA profiles which is a reason for concern due to the close relationship between household pets and humans.

The effect of self-adhesive and self-etching resin cements on the bond strength of nonmetallic posts in different root thirds

The purpose of this study was to evaluate the effect of self-adhesive and self-etching resin cements on the bond strength of nonmetallic posts in different root regions. Sixty single-rooted human teeth were decoronated, endodontically treated, post-space prepared, and divided into six groups. Glass-fiber (GF) posts (Exacto, Angelus) and fiber-reinforced composite (FRC) posts (EverStick, StickTeck) were cemented with self-adhesive resin cement (Breeze) (SA) (Pentral Clinical) and self-etching resin cement (Panavia-F) (SE) (Kuraray). Six 1-mm-thick rods were obtained from the cervical (C), middle (M), and apical (A) regions of the roots. The specimens were then subjected to microtensile testing in a special machine (BISCO; Schaumburg, IL, USA) at a crosshead speed of 0.5 mm/min. Microtensile bond strength data were analyzed with two-way ANOVA and Tukey's tests. Means (and SD) of the MPa were: GF/SA/C: 14.32 (2.84), GF/SA/M: 10.69 (2.72), GF/SA/A: 6.77 (2.17), GF/SE/C: 11.56 (4.13), GF/SE/M: 6.49 (2.54), GF/SE/A: 3.60 (1.29), FRC/SA/C: 16.89 (2.66), FRC/SA/M: 13.18 (2.19), FRC/SA/A: 8.45 (1.77), FRC/SE/C: 13.69 (3.26), FRC/SE/M: 9.58 (2.23), FRC/SE/A: 5.62 (2.12). The difference among the regions was statistically significant for all groups (p < 0.05). The self-adhesive resin cement showed better results than the self-etching resin cement when compared to each post (p < 0.05). No statistically significant differences in bond strengths of the resin cements when comparable to each post (p > 0.05). The bond strength values were significantly affected by the resin cement and the highest values were found for self-adhesive resin cement.

Bond strength of artificial teeth attached to a microwave-polymerized denture base resin after immersion in disinfectant solutions

To evaluate the bond strength between two types of acrylic resin teeth and a microwave denture base resin after immersion in disinfectant solutions for 180 days. Eighty specimens made of acrylic resin teeth (Biotone and Biotone IPN) attached to a microwave polymerized denture base resin (Nature-Cryl MC) were divided into eight groups (n = 10) according to the treatment (distilled water-control, 2% chlorhexidine digluconate, 1% sodium hypochlorite and sodium perborate solution-Corega Tabs). The shear strength tests (MPa) were carried out using a universal testing machine with a 0.5 mm/min speed. Data analysis was performed using ANOVA and multiple comparison Student-Newman-Keuls post hoc test (α = 0.05). Biotone IPN showed similar results among the groups (distilled water, 8.25 ± 1.81 MPa; chlorhexidine, 7.81 ± 3.34 MPa; hypochlorite, 7.75 ± 3.72 MPa; and Corega Tabs, 7.58 ± 2.27 MPa, whereas Biotone showed significantly lower shear bond strength values for the groups immersed in Corega Tabs (5.25 ± 3.27 MPa) and chlorhexidine (6.08 ± 2.35 MPa). Soaking the dentures in 1% sodium hypochlorite could be recommended as a disinfectant solution for dentures fabricated with conventional acrylic resin denture teeth and microwave denture base resin. For dentures fabricated with IPN teeth and microwave denture base resin, all the soaking solutions evaluated in this study could be suggested to denture wearers.